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Bearing Capacity Tests on Reinforced Earth Slabs
Abstract
Results are presented for some 65 bearing capacity tests using a 3-in. (75-mm) wide strip footing on sand reinforced with strips of aluminum foil. Three foundation conditions are considered: (1) Uniform density sand to large depth; (2) sand overlying an extensive soft layer; and (3) sand overlying a potential cavern or localized weak pocket. The vertical spacing and concentration of reinforcing layers were varied to obtain the optimum arrangement for each condition. The data show that considerable benefit may be obtained in both load settlement and ultimate bearing capacity by use of a modest amount of reinforcing.
... In the last four decades, researchers have presented numerous studies related to incorporating geosynthetic-reinforcements in improving the bearing capacity of shallow footings resting on poor subsoil using different techniques i.e. small scale laboratory model test, filed tests and numerical analysis. Extensive small scale laboratory model tests have been done by Binquet and Lee (1975); Fragaszy and Lawton (1984), Guido et al. (1986), Huang and Tatsuoka (1988), Khing et al. (1992), Manjunath (1996), Bathurst et al. (2003) Chen et al. (2007), Saran et al. (2008), Moghaddas Tafreshi et al. (2016, Sahu et al. (2016), Aria et al. (2017), Saha Roy and Deb (2017), Chen et al. (2021), and Kapor et al. (2023). Various field tests have been covered by Abu-Farsakh et al., (2008), Demir et al. (2013), Venkateswarlu et al. (2018), Zhang et al. (2023) whereas extensive numerical analysis have been studied by Latha and Somwanshi (2009) Demir et al. (2014) Lai and Yang (2017). ...
... Based on a review of related literature, five predominant failure mechanisms could be identified as a function of the width of the footing (B), depth of the first reinforcement layer (u), depth between two consecutive reinforcement layers(h), length of the reinforcement (l), number of reinforcement layers (N) and depth of the reinforced zone (R z ) [R z ¼ u þ (N − 1) � h] as presented in Figure 1(a)-(f). In the first type of failure mechanism, when u/B is relatively high (Binquet & Lee, 1975), the failure surface passes through the soil above the reinforced zone [Figure 1(a)]. In the second type of failure mechanism, when h/B is comparatively high (Wayne et al., 1998), the failure surface passes through the soil between two consecutive layers of reinforcement [Figure 1(b)]. ...
... Additionally, by employing the digital image correlation technique, the deformation and maximum shear strain contours of soil and mobilised tensile strain in reinforcement with increasing settlement of the footing is studied. Finally, an attempt has been made Binquet & Lee, 1975). (b) Failure between two consecutive layers (modified after Wayne et al., 1998). ...
... • The bearing capacity of soil determined through numerical, physical, and theoretical models increases with the use of different types and arrangements of geogrids. • The results of the theoretical equations applied to the physical models indicate that for a trapezoidal arrangement with biaxial geogrid, the equation of Sharma (2009) presents a better approximation, underestimating the bearing capacity by 7%, while the equation of Binquet and Lee (1975) overestimates the capacity by 13%. • The numerical model underestimates the bearing capacity by 14% compared to the physical model, indicating that the use of the theoretical equation of Sharma (2009) is more appropriate for trapezoidal geogrid arrangements. ...
... The theoretical results were calculated by Sharma Method [43] and Binquet and Lee Method [44], the equations to determine the increment of bearing capacity are shown below: Table 10 Maximum experimental stresses and bearing capacity ratio (BCR) for a displacement of s/B = 20% of each analysis *Due to an s/B equal to 20%, the stress in the SG presented a considerable drop for that level of deformation at 14 mm (Fig. 10b) where N: number of reinforcement layers. T: tensile strength, kN/m. ...
... Based on the results produced by the theoretical procedures, it is observed that the Sharma Method [43] is more conservative than the Binquet and Lee Method [44], with 13.5% less ultimate capacity in the results. In addition, a similarity was found between the results obtained by the Sharma Method, the numerical modeling, and the experimental results. ...
This study presents an analysis of the influence of geogrid distribution on the bearing capacity of granular soils. For this purpose, the bearing capacity is compared based on 3 arrangements, uniform, trapezoidal, and inverted trapezoidal, with 2 types of geogrids, biaxial and multiaxial, under the application of an axial load. The tests performed were analyzed in three forms in which the trapezoidal distribution was the best arrangement for biaxial and multiaxial geogrids. The first analysis considers the peaks for each stress–strain curve, the trapezoidal distribution increases the bearing capacity by 36% and 33% for biaxial and multiaxial geogrids, respectively. The second analysis considers a settlement ratio (s/B) of 10%, which had an average increment of 30.5% for the two types of geogrids. The third analysis considers a 20% of s/B ratio, which showed a 56% and 81% of bearing capacity ratio (BCR) increase for biaxial and multiaxial geogrids respectively. From an economical and environmental analysis, the trapezoidal distribution saves 7% of material compared to the traditional uniform distribution. The comparison between physical and numerical models with theoretical equations is presented.
... Several ground modification techniques are available for improving the soft soils shear strength with values lower than 15 kPa. Stone columns are frequently used amongst the various alternatives because of their benefits of enhanced load-carrying capacity, ease of installation, and associated cost benefits (Binquet and Lee 1975;Black et al. 2007;Gniel and Bouazza 2010;Indraratna et al. 2013;Fattah et al. 2016;Rajesh 2017;Abid et al. 2023b). In addition to reinforcing soft soils, stone columns are also effective in accelerating the excess pore water pressure dissipation process, dispersion of stresses in the lateral direction, reduction in settlements to avoid failure of structures, and mitigating liquefaction potential (Guetif et al. 2007; Alkhorshid et al. 2021). ...
... The efficiency of conventional and annulus stone columns was evaluated in terms of loadcarrying capacity ratio, which is defined as the bearing pressure of reinforced soil to that of unreinforced soil (Binquet and Lee 1975;Abid and Rathod 2022). Fig. 10 the load-carrying capacity ratio, against footing settlement, s/B (%) for conventional and annulus stone columns with and without geotextile encasement. ...
A geosynthetic double-encapsulated annulus stone column technique is proposed in this study to overcome limitations associated with conventional stone columns, such as limited lateral load-bearing capacity and potential issues related to aggregate dispersion in soft soils. Geosynthetic double-encapsulated annulus stone columns are consistent with conventional stone columns besides being confined in and around the surrounding soil. The performance of geosynthetic double-encapsulated annulus stone columns is primarily dependent upon their outer-to-inner diameter ratio. For this reason, comprehensive 3-dimensional numerical studies were carried out to evaluate the optimum outer-to-inner diameter ratio of the annulus stone column. The results suggest that the ultimate load-carrying capacity of an annulus stone column increases with an increasing ratio of outer to inner diameter until an optimum value. In addition, the double encapsulation enhances confinement, improving shear stiffness and reducing lateral bulging. However, the load-carrying capacity was substantially reduced beyond the critical outer-to-inner diameter ratio. A simple analytical model extending the theory of thin cylinders is also introduced to estimate the accumulated stresses and strains in the geosynthetic encasement. The proposed model operates within a simplified framework of elastic solutions that facilitate practising engineers to design and optimize geosynthetic encasements for enhanced structural performance.
... This represents an increase of 22 % at a depth of 0.20 m and a substantial increase of 63 % when the two layers were reinforced. The performance improvement of the bearing capacity increase due to triaxial geogrid reinforcement is quantified by the BCR ratio parameter, which denotes the ratio of q ult of the reinforced soil to q ult of the soft clay, as expressed in Eq.1 [49][50][51]: ...
... Interestingly, our result aligns closely with the value of 0.6B obtained by Wang et al. [32] in laboratory tests on shallow square footings on triaxial geogrid-reinforced sand under cyclic loading. Nevertheless, our recorded values fall within the comparable ranges recommended by Binquet and Lee [49], Akinmusuru and Akinbolade [53], and Yetimoglu et al. [54]. Thus, These studies revealed that the optimal embedment depth ranges from 0.25 to 0.67 B. This may suggest that the optimum depth of the top reinforcement layer determined through static loading may also apply to plates subjected to cyclic loading. ...
... This method determines what limits the actual failure load, but this limit is unclear in a method like limit equilibrium. In the limit analysis method, the foundation's final Analysis of Bearing Capacity of Shallow Foundations Located on the Reinforced Sandy Soils by Limit Analysis Method bearing capacity is calculated by using the relationship between stresses and relative deformations in continuum mechanics and using the failure criterion (Binquet & Lee, 1975). ...
... Tohidifar & Vafaeian determine the effective depth of geogrid between 0.5 and 2.5 m (Tahidifar & Vafaian, 2008). Omar et al. (1993), Binquet and Lee (1975), and Latha an Somwanshi (2009) estimated this depth to be 2, 2.5 and 2 m, respectively. As in the current study, more variables were considered, and the maximum effective depth was calculated to be between 0.5B and 1.1B. ...
Considering the high seismicity of Iran, the study of seismic force's effects on the foundations' bearing capacity is always of interest to researchers. The current study investigated the bearing capacity of a shallow foundation reinforced with geogrid using the limit analysis method in static and seismic modes. The Optum G2 software is used for this purpose. An attempt has been made to calculate the static and seismic bearing capacity of the foundation by conducting a para-metric study on the geogrid length (1B, 2B, 3B, 4B and 5B), geogrid burial depth (0.1B, 0.2B, 0.5B, 0.7B, 0.9B, 1.1B and 1.8B), geogrid layers distance (0.1B, 0.2B, 0.4B, 0.6B and 0.8B) and the number of geogrid layers (1, 2, 3 and 4). Also, these analyses were performed on different internal friction angles of sandy soil (25, 30, 35 and 40 degrees) and various foundation depths (0, 0.3B and 0.5B). The results show that the effective length of geogrid is estimated to be between 2B and 3B. Also, the geogrid's maximum effective depth is between 0.7B and 1.1B. The optimal distance of geogrid layers was estimated between 0.2B and 0.6B. Also, the optimal number of geogrid layers varies from 2 to 4, depending on the soil's internal friction angle and the foundation's burial depth. The seismic bearing capacity of the foundation estimated to be less than the static condition, and the percentage decrease of the seismic bearing capacity of the foundation compared to the static mode was varied between 7% and 20%.
... The mobilized tensile resistance of the reinforcement layers during the loading process fundamentally improves the load-carrying capacity of the reinforced soils (Akbar et al. 2022;Cicek et al. 2015;Ghazavi and Lavasan 2008;Guo et al. 2020). In the case of shallow foundations, several researchers have investigated the effect of different types of planar form of reinforcement layers on the soil loadbearing capacity with respect to the settlement of the footing Somwanshi 2009a, 2009b;Cicek et al. 2015;Abu-Farsakh et al. 2013;Aria et al. 2019aAria et al. , 2021Basudhar et al. 2007; Binquet and Lee 1975;Buragadda and Thyagaraj 2019;Fragaszy and Lawton 1984;Ghosh et al. 2005;Kazi et al. 2015;Ouria and Mahmoudi 2018;Shin et al. 2002;Shooshpasha 2016, 2020;Yetimoglu et al. 1994). In the design of shallow foundations, the settlement criteria are the primary factors rather than the bearing capacity criteria (Buragadda and Thyagaraj 2019;Tafreshi and Dawson 2010). ...
... However, as per the literature, no constant parameter of footing settlement ratio (represented by s/D) has been considered to understand the effect of the reinforcement layers towards improving the soil load-bearing capacity. Notably, (Binquet and Lee 1975) and (Fragaszy and Lawton 1984) have demonstrated the effect of reinforcement layers towards improving the load-bearing capacity of the sand bed in terms of bearing capacity ratio (BCR) up to 10% settlement ratio (s/D) of the footing. Abu-Farsakh et al. (Abu-Farsakh et al. 2013) and (Shin et al. 2002) have reported the BCR for the footing settlement (s/D) of less than 5% and some of the researchers showed the BCR up to ultimate i.e., 3 to 7% (Yetimoglu et al. 1994;Adams and Collin 1997;Hsieh and Mao 2005;Demir et al. 2013;Guido et al. 1986;Fayaz and Shah 2023). ...
It is reported in the literature that the load-carrying capacity of the reinforced sand bed increases with increasing the footing settlement. However, the nature of settlement plays a critical role in shallow foundation designs due to the conditional allowable settlement of the footings. In this present study, laboratory model tests have been performed on a model jute geotextile reinforced sand bed under 1g condition. The associated scaling laws are adopted for the geometrical parameters of the model footing and reinforcements as proposed in the literature. On the other hand, a new approach has been developed for the model reinforcements for scaling down of geosynthetic materials under 1g condition to simulate the condition of geosynthetic reinforcement layers as in the field or Ng conditions. The test results revealed that based on the scaling factors the model footing can be allowed to settle according to the criteria of footing settlement and allowable reinforcement tensile strains. Finally, the suitable guidelines have also been developed as per the safety considerations in order to understand the effect of reinforcement layers on the improvement of soil bearing capacity ratio (BCR) up to a certain settlement ratio (s/D) of the footing.
... The use of steel bars, fibers such as glass, polypropylene, polyesters, natural fibers such as palm, coir, jute, sisal, and so on has been acknowledged as an efficient soil reinforcement method [2,[4][5][6]. Metallic strips, meshes, polymeric fibers and grids have been widely utilized as planner reinforcement in the last few decades to strengthen foundations, highways, and the construction of wall [6][7][8][9][10][11][12][13]. Providing high strength geosynthetic reinforcement is yet another easy, quick, and cost-effective solution among the several stabilizing techniques available. ...
... With the inclusion of reinforcement, geocell mattress, the bearing capacity is analyzed using non-dimensional parameters such as (i) Bearing Capacity Improvement Factor, (I f ) (ii) Percentage Reduction in Settlement, (PRS%). The bearing capacity improvement factor (this factor is just like the bearing capacity ratio chosen by Binquet and Lee [7] to evaluate increases in bearing capacity due to planner reinforcement, and it is also the same as the bearing capacity improvement factor (I f ) adopted by the researchers [18,21,25,[41][42][43]45] in the past for measuring the increase in bearing capacity) equates the bearing pressure of a bed reinforced with geocell reinforcement to a bed without reinforcement at a given footing settlement level. Mathematically: ...
This paper presents the results of laboratory model experiments on a circular foundation to better understand the performance of geocell reinforced expansive soil. The subsoil in this study was formed by naturally occurring expansive soil. To strengthen the soil bed, chevron-patterned geocells formed of polypropylene geotextile were used. Geocell mattress’s height, geocell mattress’s pocket size, and the geocell mattress’s placement depth were all investigated in this testing program depth. In contrast to previous researchers, the reinforced bed’s improved performance is determined to a settlement corresponding to the soil bed’s failure settlement without reinforcement. The factors, non-dimensional, such as; If “bearing capacity improvement factor” and PRS% “settlement reduction factor”, are used to evaluate the performance of reinforced beds. The use of geocell as a reinforcement caused a substantial bearing capacity increase as well as the decrease of footing settlement, as indicated by the test findings. The use of a geocell mattress of ideal proportions placed directly below the footing base increased the reinforced bed’s bearing capacity greater than 200% and reduced footing settlement greater than 81%. The present study highlights the use of geocells toward the stabilization of the expansive soil.KeywordsBearing capacityGeocell mattressChevron patternExpansive soilCircular footing
... where , 0 are the "ultimate bearing capacities for the reinforced and unreinforced sands, respectively, and , 0 are the settlement of the reinforced and unreinforced sands, respectively, at the corresponding ultimate bearing capacity for unreinforced sand". (IF) factor is similar to the bearing capacity ratio (BCR) used by Binquet and Lee (41) to measure the increase in bearing capacity when using planar reinforcement under strip loading. It is to be noted that the pressure-settlement behaviors obtained from this study show that the tested sands, both unreinforced and reinforced, do not exhibit distinct ultimate points, with the exception of dense sand. ...
... Among these, soil reinforcement techniques have became more popular and effective in providing strength and preventing the settlement of soft ground [1,2]. Binquet and Lee [3] conducted pioneering work on soil reinforcement using aluminium foil as reinforcement to improve the bearing capacity of strip footing resting on sand. However, a significant breakthrough in ground improvement occurred with the introduction of polymeric materials, such as geosynthetics, in geotechnical engineering practices. ...
Experimental investigations were conducted using laboratory physical model tests to examine the behaviour of circular footing (diameter, D = 150 mm) resting on sand-tyre shred mattress overlying soft clay soil (undrained shear strength, Cu = 14.5 kPa), with and without geogrid reinforcement at the interface of soft soil and sand-tyre mattress. Results revealed that the inclusion of tyre shreds (7.5% by volume) with sand, over the soft soil subgrade, increase the load-bearing pressure by 200.01% (at a height of sand tyre mixture, hSTM = 1.5D), i.e., 3.5 times higher in comparison to the soft soil subgrade foundation system S-I. Further, with the use of geogrid in between soft soil subgrade and sand-tyre mattress, bearing pressure foundation system S-VI (i.e., clay + geogrid + sand + 7.5% tyre-shred) is increased by 211.84% at hSTM = 1.5D, which is nearly 4.1 times higher than S-I foundation system. It was also observed that the footing settlement was substantially reduced with the application of geogrid between the soft soil subgrade and the sand-tyre mattress. Thus, it can be stated that the addition of tyre-shred to the sand over the soft soil subgrade, with or without geogrid reinforcement, is an effective techniques to improve the performance of soft soil subgrade systems. Moreover, this study offers a practical and sustainable solution for the application of tyre-shreds in geotechnical engineering to enhance the load-bearing capacity of soft soil subgrades.
... To address these issues, soil reinforcement techniques have emerged as crucial solutions for enhancing strength and also reducing settlement in soft ground [1,2]. One of the early demonstrations of soil reinforcement was pioneered by Binquet and Lee [3], who improved the bearing capacity of strip footing resting on sand using aluminium foil strips as reinforcement. However, a significant breakthrough in ground improvement occurred with the use of polymeric materials like geosynthetics in geotechnical engineering practices. ...
The growing global issue of waste tyres, which are non-biodegradable, poses serious environmental risks, with improper disposal and burning contributing to air and water pollution through the release of harmful chemicals and greenhouse gases. However, waste tyres possess unique engineering properties such as high tensile strength, permeability, durability, fatigue resistance, resilience, and flexibility. This study explores the potential of utilizing waste tyres to enhance soil strength through experimental investigations. Laboratory model tests were conducted on circular footing (150 mm diameter) placed on various foundation systems, considering sand or sand-tyre shred mattress overlying a soft clay bed (Cu = 14.5 kPa), with and without geogrid reinforcement at the interface of soft clay and sand-tyre. Results revealed that the maximum improvement in bearing capacity of the foundation systems, with or without geogrid, was observed at a thickness of sand layer (hs) or sand-tyre mixture (hSTM) = 1.5D, over the soft clay. Results also revealed that with the inclusion of tyre shreds (7.5% by volume) with sand, over the soft clay bed, the bearing pressure of foundation system S-IV increased by 200.01% (at hsTM = 1.5D) in comparison with S-I. This improvement in bearing capacity of S-IV (i.e. clay + sand + tyre) was 3.5 times than S-I, which is similar to the improvement in bearing capacity of foundation system S-III (i.e. clay + geogrid + sand). Based on the experimental evidence, it can be suggested that the application of tyre shred is beneficial in geotechnical engineering practices to improve the performance of soft clay foundation systems.
... Over the past few decades, there has been significant attention toward reinforcing soil beneath footings on horizontal ground. Incorporating reinforcement elements within the soil matrix has been shown to enhance footing performance under various loading conditions [9][10][11][12][13][14][15][16]. ...
This study investigates the influence of a horizontal geogrid layer reinforcement on the ultimate bearing capacity (UBC) of a strip footing under static and seismic loading conditions resting on a c-ϕ soil slope subjected to uniformly distributed load using Finite Element Limit Analysis (FELA). The Bearing Capacity Ratio (BCR), which is the ratio of the UBC of the strip footing with and without reinforcement in soil slope, quantifies the influence of the reinforcement on the UBC of the footing. A parametric analysis is carried out to evaluate the influence of the vertical depth of geogrid placement (u/B), offset distance of the footing (x/B), slope inclination (β), and the horizontal seismic acceleration coefficient (kh) on the BCR. A reinforcing layer beneath the foundation can improve the UBC by up to 1.8 times under static and seismic loading, and this improvement is governed by u/B, x/B, β, and kh values. The optimal depth for maximizing this capacity ranges as u/B = 0.5–0.75. The position of the footing on the slope (x/B) also impacts the effectiveness of the geogrid reinforcement. The study identified x/B and u/B as crucial factors influencing the footing-slope system’s failure mechanisms. This investigation developed various advanced machine-learning models to predict BCR values, including Fine Tree regression, Linear Regression, Linear SVM, and Narrow Neural Networks. The Narrow Neural Network outperformed the others, achieving a lower Root Mean Squared Error (RMSE) of 0.0334 and a higher R² value of 0.9538, indicating its strong predictive power compared to the other models.
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... The plate load test is a common method used to evaluate the performance of materials, such as geofoam, when placed on a roof slab or any other load-bearing surface (Binquet & Lee, 1975a). In the context of the Grand Egyptian Museum Metro Station, the plate load test has been conducted to assess the working mechanism of EPS geofoam blocks on supporting the applied load and distributing it across the roof slab. ...
Underground metro stations play a crucial role in urban transportation systems, which necessitating the need for effective structural design and maintenance. The use of lightweight materials such as backfill above underground metro station roofs has gained significant attention due to their potential in reducing internal forces on the structure. This study aims to investigate the effect of using geofoam as a backfilling material on reducing the internal forces within underground metro stations elements. EPS Geofoam, a lightweight and cellular plastic material, offers various advantages, such as low density, high compressive strength, and excellent insulating properties. These properties make it a prominent candidate for mitigating the internal forces induced by the applied loads on underground metro station roofs. By replacing traditional backfilling materials with geofoam, the overall weight of the fill above the roof is significantly reduced, leading to a reduction in the applied loads and subsequently minimizing the internal forces experienced by the structure. To assess the effect of geofoam, a comprehensive numerical analysis was conducted by using finite element modeling through PLAXIS2D package software. Various scenarios of loading and stag of construction were considered, simulating different types of live loads. The study encompassed a comparison of internal forces, encompassing bending moments, shear forces, and axial forces, between the conventional backfill and the backfill utilizing EPS geofoam. The primary focus of this research is to emphasize the advantages associated with integrating geofoam as a material for backfilling. In addition to the potential of geofoam in reducing internal forces and optimizing the structural behavior of underground metro stations. The implementation of geofoam-based backfilling can lead to enhance the safety, increase cost-effectiveness, and improve sustainability of underground metro station structures. The results of the study demonstrated that the incorporation of geofoam as a backfilling material above the roof of underground metro stations leads to a substantial reduction in internal forces. The lightweight nature of geofoam significantly decreases the bending moments, shear forces, and axial forces acting on the roof structure, improving its overall performance and extending its service life.
... Three modes of bearing capacity failure of a strip foundation on reinforced earth, (afterBinquet and Lee, 1975a). ...
Reinforced earth technique has become one of the most important methods of soil improvement owing to its simplicity of construction and cost saving.
The present research aims at investigating the potential benefits of using the geogrids to improve the bearing capacity and reduce the settlement of shallow foundations, studying properties of some geogrids and measuring the straining mechanism occurring in the geogrid layers during loading. Several parameters were studied which include the effect of: footing types (three models were used; strip, circular and square), geogrid types (twelve types of geogrids were used, manufactured in various countries), aperture size and stiffness of geogrid. To implement these objectives, a total of one hundred sixty five tests were performed to study the behavior of reinforced sand foundation and the mechanical properties of geogrids. The single rib tensile test was conducted on geogrids.
The test results showed that the geogrids Tensar SS2 and Netlon CE121 have tensile strength and elastic modulus higher than other geogrids made by different manufactures. It is also found that the effect of tensile strength and stiffness in kN/m is more significant than the elastic modulus in kN/m2 when geogrids are used as reinforcement in the soil. The reinforced sand model test results showed that the inclusion of reinforcement can significantly improve the soil bearing capacity and reduce the footing settlement for all footing models and geogrid types. The bearing capacity increased up to about 271, 278 and 336 % for strip, circular and square footings, respectively, and the settlement decreased about 261, 322 and 380% for strip, circular and square footings, respectively. The bearing capacity increases when the stiffness of geogrid becomes very high. The present results did not reveal a significant trend of influence for aperture size of geogrid on bearing capacity, because it was not possible to fix other influential parameters of the geogrids.
In this research, the straining mechanism and elongation occurring in the ribs of geogrids embedded in sand during the bearing capacity tests have been investigated, a subject which has not been tickled yet. Testing conditions were varied in reference to footing types and the type of geogrid. The horizontal and vertical distances of strain gauges from the centerline of footing base were varied in order to find out the distribution of strains in all the geogrid layers and produce a good image of the straining mechanism. The result illustrated that the values of strain and elongation were influenced by the footing and geogrid types and the
III
horizontal and vertical distances. The strain and elongation have gradually decreased when moving down underneath the footing and also die out with increasing the distance from the footing center. The strain and elongation vanished at the edge of reinforcement for all footings and geogrid types except geogrid Tensar SS2 when using strip footing, and they were also zero in the last geogrid layer at depth B for all footings and geogrid types. The test results showed that the geogrid strains during loading are very small. The actual reinforcement strains in the design of geogrid reinforced structures may be considered to lead to more economic design. The test results may indicate that the inclusion of reinforcement can redistribute the applied load and achieve a more uniform stress distribution.
Three bearing capacity equations have been compared with the experimental results on sand alone, and a good agreement is obtained depending on the footing type.
Finally, a finite element program Plaxis-3D foundation has been used to analyze the results of reinforced and unreinforced sandy soil using three types of footings and five types of geogrids. A comparison is made between the numerical and experimental results, shows a good agreement is obtained.
... The revolutionary advancement came with the introduction of versatile geosynthetics, particularly geotextile, geogrid, and geocell. Geotextile is a fabric material designed to enhance soil stability and drainage [2], and geogrid is a mesh-like structure providing tensile strength and load distribution [3]. Geocell, a threedimensional honeycomb confining system, was developed by Webster and Watkins [4], further expanding the range of geosynthetic applications. ...
In the last decades, geosynthetics have established their efficacy in enhancing bearing capacity and reducing settlement in various applications. Despite these advantages, researchers have identified minimal benefits associated with conventional geosynthetic reinforcement at low deformation levels. Consequently, the concept of geosynthetic prestress has gained recognition as a promising solution, aiming to enhance performance and expand its applicability across all deformation levels. While existing studies focus on prestressed geotextile or prestressed geogrid, this research uniquely delves into the behavior of prestressed geocell-reinforced sand. The study experimentally investigates various parameters, including geocell placement depth, cell height, geocell layer length, prestress magnitude, and the stage of tension release, under a strip footing vertically loaded, offering a comprehensive comparison with the un-reinforced or un-prestressed cases. The findings emphasize the superior effectiveness of the geocell prestressing process, capitalizing on its distinctive advantage of tension release- a feature not shared by prestressed geotextiles or geogrids. Furthermore, the research identifies critical design parameters, highlighting that the optimal geocell placement depth and layer length correspond to 0.2 and 7.5 times the footing width, respectively. Additionally, the study establishes that the optimal prestress magnitude is 45% of the geocell ultimate tensile strength, with the most effective tension release occurring at 30% of the ultimate capacity of the un-reinforced case.
... They go by the names band drain and wick drain as well. Prefabricated vertical drains (PVD) and sand drains are the two most popular varieties of vertical drains [18] . ...
... The parameter η γ is similar to the improvement factor (I f = p r /p u ) offered first by Binquet and Lee (1975), and it has been used in many studies to represent the efficiency of the treating methods (Shadmand et al. 2018b ...
Most research studies on the behavior of footings on geocell-reinforced slopes were conducted using experimental model tests on small-scale slopes. Very few studies can be found in relation to 3D analyses using detailed geocell structures. It is, therefore, the aim of the present study to investigate this problem by using a 3D finite element analysis. The study begins with verifying the accuracy of the applied finite element method using the results of the experimental model tests on the unreinforced and geocell-reinforced footings on slopes. It continues with studying the effects of main design factors such as the slope angle (β), the depth of the geocell mattress (u), the soil internal friction angle (ϕ), and the footing setback (a) on the bearing capacity of the geocell-reinforced footings. Numerical results suggest that an increase in soil internal friction angle and a decrease in slope angle would both enhance the bearing capacity of unreinforced and reinforced footings. The geocell reinforcement proves to be more effective in improving the bearing capacity of steeper slopes with small friction angles. In addition, the optimum depth of the geocell placement was found to be 0.1 times the footing width (0.1B) regardless of the β and ϕ. Irrespective of the β, the optimum footing setback ratio (a/B) was obtained at 0.5. As a/B ˃ 2, the effect on bearing capacity vanishes. At a constant footing setback ratio (a/B < 2), the use of geocell reinforcement is more effective for steeper slopes. The findings in this numerical study are of practical significance to the geotechnical engineering community.
... Since Binquet and Lee [2] investigated the behavior of soil reinforced with metal strips, numerous researchers have carried out experimental, numerical, and analytical works to study the load-settlement behavior of the footings resting on reinforced soil bed [3][4][5][6][7][8][9][10]. Omar et al. [6] studied the increase in the bearing capacity ratio (BCR) of the square and the strip footing resting on sand reinforced with geogrid layers. They reported that the maximum BCR occurred when the geogrid layers were placed at a depth of approximately 1.4 and 2 times the width of footing (B) for square and strip footings, respectively. ...
This study introduces a novel application of gene expression programming (GEP) for the reliability analysis (RA) of reinforced soil foundations (RSFs) based on settlement criteria, addressing a critical gap in sustainable construction practices. Based on the principles of probability and statistics, the soil uncertainties were mapped using the first-order second-moment (FOSM) approach. The historical data generated via a parametric study on a validated finite element numerical model were used to train and validate the GEP models. Among the ten developed GEP frameworks, the best-performing model, abbreviated as GEP-M9 (R2 = 0.961 and RMSE = 0.049), in the testing phase was used to perform the RA of an RSF. This model’s effectiveness in RA was affirmed through a comprehensive evaluation, including parametric sensitivity analysis and validation against two independent case studies. The reliability index (β) and probability of failure (Pf) were determined across various coefficient of variation (COV) configurations, underscoring the model’s potential in civil engineering risk analysis. The newly developed GEP model has shown considerable potential for analyzing civil engineering construction risk, as shown by the experimental results of varying settlement values.
... French architect and engineer Henri Vidal were the first to use systemic soil reinforcement in modern society. Binquet and Lee (1975), developed research with planar aluminum strips, providing the groundwork for systematic investigation. Metal reinforcement in a planar shape, which can be costly and corrosive, was often utilized. ...
... The effectiveness of granular materials reinforced with geogrids depends on several parameters. These parameters include properties of the granular materials, dimensions of loading plate, geogrid type, depth of embedment, aperture size, flexural stiffness, radial stability, tensile strength, and the influence zone of geogrids [14][15][16][17][18][19][20][21][22][23]. While Bussert and Cavanaugh [24] initially focused on the influence zone of geogrids (Δu t ) and reported as 0.35 m for granular soils. ...
Triaxial geogrid (TAG) reinforcements are highly desirable modern techniques that improve the bearing pressure of granular materials. Improvement of the bearing pressure of a granular material (homogenous and layered systems), stabilized with polypropylene TAG reinforcement, is examined by using plate load tests and a unique numerical constitutive Tensar stabilized soil model (TSSM). The study is focused to evaluate: (a) the mechanical performance of unstabilized granular soil (homogenous) and aggregates overlying granular soil (layered system); (b) the effect of embedded depths (ut) of TAG-reinforced stabilized granular materials; and (c) to estimate the improvement factors (IF) at a settlement equal to 2% of plate diameter (i.e., S/b = 0.02) for various embedded depth to plate diameter ratios (ut/b). Experimentation and finite element analysis (using TSSM) demonstrate that the TAG reinforcement improves the structural ability of granular materials and thus support traffic loads. The significant research findings are strengthening of granular materials for the ideal embedded depth. The good agreement between realistic testing approaches and numerical predictions emphasizes the significant strengthening of granular materials using TAG reinforcement in these circumstances.
... However, not only is it beneficial to improve the 'weak' soil, but it is also advantageous to strengthen the comparatively stable but inadequate ground(in terms of 'complexity of requirements'). It started with Vidal (Vidal 1969) and progressed through the pioneering work of Binquet and Lee (Binquet and Lee 1975). Strip-metallic reinforcements were initially taken over by geosynthetics in various forms, including geocells (three dimensional) geotextiles and geogrids (planar type). ...
Extensive research has been conducted on the performance of footings on both uniform and layered soil strata, focusing on conventional footing designs. Ring footings, on the other hand, have not undergone thorough field and laboratory evaluations, particularly for multi layered soil strata. A series of laboratory tests were performed with ring and circular footings resting on different homogeneous and layered soil strata. The study considered multiple unreinforced and reinforced foundation configurations by altering the thicknesses (H) of the top layer, in the range of 0.66–2.66D, overlying the subgrades of varying relative density, ranging from very loose (DrB = 30%) to stiff (DrB = 50%, 80%). The findings of the study suggest that the performance of foundations is significantly affected by the placement of geogrid at the interface between the layers. A profound improvement in the performance with respect to the load bearing capacity and reduction in footing settlements was observed due to the introduction of geogrid. However, the extent of improvements was influenced by the relative density of the subgrade, the level of settlement experienced by the footing, and the thickness of the top layer. The effectiveness of reinforcement was reduced as the lower layer stiffness and the top layer thickness increased. The study observed the highest improvement of 2.3 in terms of bearing pressure ratio for H = 0.66D and DrB = 30%. In both the unreinforced and reinforced cases, it was observed that the ring foundation with the optimal diameter ratio exhibited higher bearing pressures than the circular foundation with the same outer diameter.
... Binquet and Lee [22] summarized the cases of footing failure on reinforced sand as follows: • Shear failure above the uppermost reinforced layer. When the reinforcement layer depth is not proper, the upper soil layer behaves like it's not reinforced, and the shear will not penetrate the reinforced area. ...
... The initial investigation into the effect of soil reinforcement on increasing the bearing capacity of footings was carried out by Binquet and Lee [1,2]. what's more, was then sought after by various others. ...
Recently there has been a strong demand for the use of jute geotextile for improving mechanical, in addition, and physical properties of cohesive less soil. The research aims to study the effect of applying jute geotextile on subsurface layer of sandy soil; additionally, this paper presents the results of laboratory load tests on model circular footings supported on reinforced sand beds. The experimental results showed that the most increase in ultimate bearing capacity (UBC) of footings on supported soil (by jute geotextile) is viewed as expanded by a variable of 2.02 when compared with soil without jute geotextile. Also to Verification of the experimental results of bearing capacity were compared with the theoretical bearing capacity that was determined by Meyerhof, Terzaghi, and Brinch. The experimental results are in good agreement with the Terzaghi equation by factor of 0.99, while Meyerhof equation and Brinch Hansen by a factor 0.89 and 0.91 respectively.
... For instance, the tires manufactured from tire manufacturing industries are used in automobiles such as trucks, buses and cars [25][26][27] . Non-Governmental Organizations report that around 25 million waste tires are dumped in landfills and counsel to implement these tires as a recyclable material exclusively for construction [28][29][30][31][32][33][34][35][36][37][38] . From the investigation, Researchers found that the higher reduction caused by shear failure is disregarded while looking at footing failure in the analysis [39][40][41] . ...
In this research, the performance pertaining to tire crumb obtained from scrap tire processing plants
is discussed. These tire crumbs are blended with soil at a 30% ratio. When subjected to seismic load,
the performance of the 30% tire crumb combination is superior to the 0% tire crumb combination. The
investigation is classified into two phases. Phase 1 of the study involves conducting an experimental
investigation by applying cyclic loads to a model footing that was resting on the soil with and
without tire crumbs. This study reveals that a 30% tire crumb combination achieves optimum energy
absorption and minimal footing stiffness, which is a crucial component needed for base isolation.
Additionally, using the PLAXIS 2D software package, finite element analysis was carried out during
the second phase of the study. For this study, a three-story residential building close to the border
between India and Nepal is used. Three different disastrous seismic excitations are applied to the
building. From this analytical analysis, it is reported that a 60–70% reduction in acceleration is
attained for 30% tire crumb combination with soil. Therefore, from the two phases, it is evaluated that
the inclusion of tire crumbs with soil is an excellent seismic base isolation material.
... The mechanism for stress dispersion is also known as the wide slab mechanism, which was initially observed by Binquet and Lee [15]. In addition, several researchers [29,30,105,113,129] conducted 1-g model testing to explore the vertical load distribution mechanism in the geocell-reinforced layer, and it has been found that the interconnected geocells create a composite structure that behaves like a wide slab, dispersing the applied load and improving the load-carrying capability of foundation soil. ...
Geocell has become increasingly popular as reinforced material in various fields of civil engineering over the last few decades. Geocells can be a solution to the problems associated with paved and unpaved road construction over weak soil. Many researchers have conducted laboratory model testing, field trials, numerical, and analytical studies to assess the significant impact of geocell reinforcement. The current paper reviews various studies available in the literature and provides a summary of the main contributions. The current study illustrates that improved performance owing to geocell reinforcement is dependent on several factors and variables, including the relative density of infill material, geocell rigidity, and geometry, placement location of geocell and geocell type. Furthermore, a comprehensive review of the various literature and design guidelines was presented to assess the performance improvement of geocell-reinforced pavement in terms of rut depth, vertical stress distribution, resilient modulus, modulus improvement factor, and traffic benefit ratio. The important findings from a review of the relevant literature indicate that the geocell provides confinement, membrane effect, and larger stress distribution, resulting in a greater load-carrying capacity and modulus of reinforced soil. Several studies highlighted that due to the usage of geocells as a layer of reinforcement, a 13 to 71% reduction in rut depth occurred. Furthermore, the modulus of the geocell-soil composite may improve by 2.5 to 3.5 times of modulus value of the unreinforced section due to the increment of the geocell height.
... Research on the evaluation of the bearing capacity of foundations on reinforced soils is scarce, and most studies are based on traditional laboratory or field tests. Through experimental studies, Binquet and Lee [8] first demonstrated the significant enhancement in the bearing capacity of reinforced sand footings. Huang and Tatsuoka [9] predicted the variation of the bearing capacity of reinforced sand footings and analyzed the influence of material parameters and reinforcement arrangement. ...
The study of analytical solutions for the bearing capacity of reinforced soil foundations is a very important topic in engineering mathematics. Existing evaluations of the foundation-bearing capacity on reinforced soils are based on dry conditions, while many foundations are located on unsaturated soils in real engineering. In this paper, a new formula for the bearing capacity of reinforced strip footings on unsaturated soils is presented. Two sliding failure mechanisms are constructed based on the position of the reinforcement layer relative to the sliding surface. The distribution of apparent cohesion in the depth direction is calculated by considering the effect of matrix suction. By additionally considering the work conducted by the reinforcement and the contribution of the apparent cohesion, the bearing capacity formula is obtained using the upper bound theorem of limit analysis. The bearing capacity solution is obtained by adopting the sequential quadratic programming (SQP) algorithm. Comparing the results under two failure mechanisms, the optimal bearing capacity and the optimal embedment depth of reinforcement are obtained. The results of this paper are consistent with those of the existing literature. Finally, the effects of reinforcement embedment depth, effective internal friction angle, uniform load, and unsaturated soil parameters on the optimal bearing capacity are investigated through parametric analysis. This paper provides useful recommendations for the engineering application of reinforced strip footings on unsaturated soils.
... The bearing capacity performance of the GSI system due to the inclusion of reinforcement is evaluated in terms of the dimensionless parameter, bearing capacity improvement factor (If) proposed by Binquet and Lee [79] using Eq. (3): where, qr is the bearing pressure of the reinforced soil foundation for given settlement, and qo is the bearing pressure of the unreinforced soil foundation at the same settlement. ...
In the present study, a geotechnical seismic isolation (GSI) bed, composed of geosynthetic-reinforced sand–rubber tire shred mixture layer between the base of the building foundation and the supporting soil medium, is considered to mitigate ground vibrations. The index and engineering properties including dynamic properties of sand–rubber tire shred mixtures are carried out to assess their suitability for seismic base isolation of buildings. In addition to that, the liquefaction resistance of sand rubber mixtures is also evaluated. Further, laboratory-based model experiments and Finite Element (FE) modeling was carried out for footing resting on geogrid-reinforced GSI layer under static loading. Further, 2D seismic response of a typical building on GSI was also carried out using finite element code ABAQUS. Finally, results of a series of field experiments conducted to study the response of model footing resting on the geogrid-reinforced GSI bed subjected to horizontal ground vibration are presented. Further, a 3D finite element (FE) model of the field study was developed in the time-domain to simulate and investigate the response of geogrid-reinforced GSI bed on a multi-layered soil system for different surface wave characteristics. In general, it was found that GSI with geogrid reinforcement is found to be effective in the mitigation of ground vibrations due to earthquakes and other source of vibration.
... To analyze the data, the DS7 program was utilized with the assistance of 32-channel input data collection devices known as ADU (Autonomous Data Acquisition Units). Equation 1. was used to calculate the Bearing Capacity Ratio (BCR) (Binquet and Lee 1975). This ratio is commonly used to indicate the (1) ...
Granite and marble are widely produced and utilized in the construction industry, resulting in significant waste production. It is essential to manage this waste appropriately and repurpose it in recycling processes to ensure sustainability. The utilization of waste materials such as marble and granite waste (MGW) has become increasingly important in geotechnical engineering to improve the physical and mechanical properties of weak soils. This study investigated the applicability of utilizing MGW and cement (C)-MGW mixtures to improve clayey soil. A series of model plate loading tests were carried out in a specialized circular test tank to assess the influence of MGW and C-MGW mixing ratios on clayey soil samples. The samples were prepared by blending MGW and C-MGW in predetermined proportions. It is found that the bearing capacity of clay soil increased by approximately 71% when using MGW and C additives. Moreover, the consolidated settlement values of the clay soil decreased up to 6 times compared to the additive-free case.
... Vidal [1] was the first to incorporate reinforcement in soil media. Subsequently, several experimental [2][3][4][5][6][7][8][9] and computational studies [10][11][12][13][14][15][16][17][18][19][20][21] have been published in the literature on reinforced strip footings. Some experimental and numerical studies were also conducted for reinforced circular footings [22][23][24][25][26][27][28][29][30]. ...
This research investigates the bearing capacity of a ring-shaped foundation on layered sand reinforced with a geogrid at the interface. The study employed lower and upper-bound limit analysis methods, along with finite elements and second-order conic programming (SOCP). The Mohr–Coulomb yield criterion and associated flow rule were used to characterize the behavior of the sand. The bearing capacity was evaluated and presented in a non-dimensional form for different combinations of the inner-to-outer ring diameter ratio (Di/Do) and the friction angles of the top and bottom layers (ϕ1,ϕ2). The computational results indicated that the densification of the top layer significantly enhanced the bearing capacity, reaching up to 82 times that of the homogeneous case. Additionally, the placement of the geogrid reduced the thickness of the dense top layer by up to 30%. Furthermore, a sensitivity analysis model was proposed, based on 1746 data sets obtained from finite element limit analysis, utilizing the Multivariate Adaptive Regression Spline (MARS). Consequently, the numerical results correlated well with an R2 of 0.998. Additionally, MARS results show that H/(Do−Di) is the most crucial parameter influencing the output, followed by Df/(Do−Di), ϕ1, Di/Do, ϕ2.
This study deals with extensive full-scale instrumented model testing on pavement sections with and without geocell reinforcement to evaluate the impact of different vehicular loading conditions on pavement performance. This study employed three different loading conditions, that is constant axle load and frequency (LC-1), constant axle load but varying frequency (LC-2), and constant frequency but varying axle load (LC-3). For both unreinforced and reinforced pavement sections, the permanent deformation values obtained for LC-1 conditions are about 15% to 16% lower than those obtained for LC-2 and LC-3 conditions, indicating that LC-1 may underestimate deformation potential under more severe loading scenarios. The study reveals that vertical stress is more significantly affected by load magnitude than by loading frequency. Furthermore, vertical stress increased with higher axle load and lower frequencies, emphasizing the importance of considering overloading conditions and lower loading frequencies in pavement performance assessments. The geocell strain results revealed that load magnitude significantly influences strain, highlighting the role of geocell in providing lateral confinement. While most previous studies and design codes focus on the LC-1 condition, this study highlights the importance of incorporating varying axle loads and frequencies for a more comprehensive understanding of pavement performance.
This study investigates the response of geosynthetic-reinforced foundation beds to loads and proposes a method to estimate the modular ratio of the reinforced soil layer from the stresses measured at the reinforcement–soil interface or below. The reinforced foundation bed, overlying the in situ soil layer, is considered as a two-layered system. It is noted that the reinforcement effectively redistributes applied loads, reducing stress increments in the soil beneath the centre. Available theoretical solutions for a two-layered soil system, with a stiff layer overlying a relatively soft layer, are applied to the stresses measured beneath the reinforced soil bed. The modular ratio, that is the ratio of the modulus of the reinforced foundation bed with respect to that of the in situ soil, is expressed as a function of the ratio of stress at depth to the applied stress at the surface. A method to estimate the modular ratio of the reinforced foundation bed based on the stress ratio is presented. The versatility of the method in estimating the modular ratio of the reinforced foundation bed is illustrated by analysing test results from literature, and the moduli of geosynthetic-reinforced beds, estimated for the first time, are presented.
Stone columns and sand layers reinforced with geosynthetics are effective methods for improving the performance of foundations placed on soft clay soil. Stone columns increase the load-carrying capacity by using the soil’s natural circumferential confinement. The issue of sand columns bulging was solved by grouting these columns, which resulted in extremely robust and solid columns. The pressure of the grouting column works to generate pressure from the column towards the soil increase the force of friction and fill all voids and cavities in the event of its presence in the soil. It was concluded that grouted sand columns can moderately improve the bearing capacity ratio (BCR) of a soft clay bed, increasing it to 1.9 within the optimal length and spacing of the footing area, without using a sand cushion. The BCR is defined as the ratio of the bearing capacity (q) of reinforced soil to that of unreinforced soil at specific s/B ratios, where s/B represents the ratio of footing settlement to footing width. Grouted sand columns and geogrid reinforcement increase bearing capacity by 3.6 times if the grouted sand columns are within the footing area, 4.2 times if one row is installed outside the footing, and 4.5 times if two rows are installed outside the footing, assuming H/B = 1 (H = thickness of sand cushion, B = footing width). At H/B = 1.5, the bearing capacity ratios increase by 5.2 times when the grouted sand columns are within the footing area, 6.4 times if one row is installed outside the footing, and 7.5 times if two rows are installed outside the footing.
This paper outlines the suitable techniques employed for soil improvement in Heavy industries, oil & gas refinery, and petrochemical Plants. The materials and procedures will be detailed within this paper, with any exceptions to the specifications clearly indicated. The primary scope of work involves the filling of sand and gravel, as well as the injection of soil cement at designated cavity locations beneath the concrete grade slab in areas where space is limited and accessibility to the ground is challenging. The proposed method aims to fill the voids between the top of the foundation soil and the underside of the slabs, while ensuring the provision of all necessary equipment, tools, and a skilled workforce for geotechnical operations. Each testing location, including DCP Testing, void detection, and the installation of shallow monitoring wells, will be addressed in accordance with the specific site conditions.
This paper exhibits an experimental study the effect of numbers of layers of reinforcement on the behavior of shallow footing under machine foundation. A reinforcement was inserted in to the sandy soil of relative density 50% during the raining techniques with 30*30cm at distance (0.5B, B,2B,3B) in a steel container with dimensions (50*50*55) cm. The test was performed under a machine foundation at frequency 10, 15 HZ. This research aims to find the optimal number of layers of reinforcement with geogrid under the square foundation under the machine foundation. For this purpose, laboratory experiments were conducted. The factors that were studied to find the optimal number of layers of reinforcement include the optimal number of layers of reinforcement, as well as displacement amplitude, velocity, acceleration, and settlement. The results showed at frequency 10 HZ, the optimal number of layers was one layer. The percentage of improvement in displacement, velocity, and settlement was (26%,39% and 75%), while acceleration increased when using one layer. At frequency 15 HZ, the optimal number of layers was four layers. The percentage of improvement in displacement, velocity, and settlement was (34%,44% and 66%). We conclude from this research that the type of reinforcement gave good results in reducing displacement amplitude, velocity, and settlement, but does not give good results in reducing acceleration.
This paper presents the findings regarding the displacement-load behavior of both plane strain model experiments’ ultimate load and numerical analyses conducted on unreinforced and reinforced sand slopes loaded with strip footing. The investigated parameters include the impact of the reinforcement and varying eccentricity on the ultimate load and displacement of the strip footing. A group of finite element analyses was performed with the 3D plane strain model and the computer code ANSYS software to validate the results of the model experiments on a slope. The results from both the numerical analyses and model experiments suggested that the use of reinforcement could enhance the load–displacement behavior of the central and eccentrically loaded footings. The load–displacement curves demonstrated that a higher load eccentricity leads to a reduction in the ultimate load of the strip footing. The concordance between the computed and observed results was reasonably satisfactory for the load displacement and the overall behavioral trend.
This experimental investigation describes an extensive series of reduced laboratory scale tests, conducted on circular and ring footing models rested on a geogrid reinforced cohesionless soil. The study examined the impact of several factors at different relative sand densities, such as the inner to the outer diameter ratio of the ring footing, the number of geogrid reinforcements, the depth of the initial reinforcement, and the vertical spacing between the geogrids, as well as the geogrid stiffness. The results indicated that the optimum diameter ratio of ring footings resting on loose or medium-dense cohesionless soil is 0.40 at which the maximum bearing capacity is reached, leading in a cost-effective design of the footings, while for the dense soil, a diameter ratio of 0.45 is the optimal ratio. Also, the results indicated that the optimum number of reinforcement layers which after the bearing capacity improvement can be considered negligible is three layers for the circular footing and four layers for the ring footing model. To achieve the maximum increase in bearing capacity, the study identifies optimal values for the depth of the first geogrid reinforcement layer and the vertical spacing between reinforcements, which apply to circular and ring footing. While the stiffness of the reinforcement has a significant effect on the bearing capacity, this effect is not proportional.
The substantial annual consumption of natural resources by the building sector raises concerns about future depletion. Conversely, the accumulation of industrial waste in substantial volumes presents crucial environmental hazards. This study explores the utilization of granulated ferrochrome slag (GFS) as a sustainable alternative to sand for shallow foundations which has been little explored for this purpose. The model test is conducted on GFS with a relative density of 30% in a test tank of 1.6 m (L) × 1.0 m (W) × 1.2 m (D) with and without reinforcement to find the ultimate bearing capacity of surface square footing. Two reinforcement geogrid and geotextile types were contemplated in a GFS bed with three layers of conditions at various depths. Bearing capacity ratios (BCR) of 1.29, 1.45, and 1.56 were observed for single, double, and triple layers of geogrid; geotextile outperformed geogrid with BCR of 1.46, 1.92, and 2.28 consecutively. A numerical simulation using PLAXIS-3D has been carried out to validate the model test data. The outcomes of the numerical and experimental results showed a good agreement among themselves. Angular particles with high specific gravity and higher friction angle make GFS a better loading-bearing geomaterial than other granular materials. The chemical examination of GFS found acceptability regarding its leachability within allowable limits. All these factors make GFS satisfactory to use as a reinforced foundation bed material.
A detailed numerical analysis has been accomplished to explore the influence of geometrical parameters of geocell reinforcement on the load carrying behavior of footing using three-dimensional finite element techniques. The influencing parameters considered such as shape, height, pocket size, stiffness of geocell reinforcement, and friction angle of infill materials. Results indicate that the inclusion of the geocell reinforcement irrespective of the shape of geocells significantly enhances the strength and stiffness of the foundation system. However, the pressure-settlement behavior is noticeably influenced by the shape of the geocells. The load carrying capacity is found to be minimum for square shaped (i.e., 400 kPa) followed by circular, diamond, and honeycomb shapes (i.e., 1000 kPa) of geocells. With increase in height of geocell mattress, the performance of the foundation system increases noticeably. The findings indicate that the load bearing capacity increases significantly up to a height ratio (H/B) of 1.5, beyond which further increment found to be marginal. Additionally, the efficacy of the system improves with increase in stiffness of reinforcement and reduces with increase in geocell pocket size. Furthermore, it is evident that the higher frictional angle of the soil mobilizes enhanced resistance on the interface, improving the overall performance.
Taşıma gücü bakımından zayıf zeminler üzerine inşa edilen yapılar için temel tasarımı oldukça önemli bir problemdir. Bu tür problemlerin çözümünde yüzeysel temel sistemlerinin yetersiz kaldığı durumlarda zemin iyileştirme yöntemleri tercih edilebilir. Taşıma gücü zayıf zeminlere geosentetik donatılar yerleştirilerek zeminin iyileştirilebilmesi mümkün olmaktadır. Bu çalışma kapsamında daire ve ring kesitli olarak hazırlanmış olan mikrogrid donatı ile güçlendirilmiş gevşek kum zemine yerleştiren ring kesitli ve daire kesitli temellerin eksenel kuvvet altındaki davranışlarını tespit etmek amacıyla 32 adet laboratuvar deneyi gerçekleştirilmiştir. İlk donatı derinliği ve donatı iç çapı/dış çapı oranı değerleri değiştirilerek taşıma gücü bakımından optimum donatı parametreleri araştırılmıştır. Yapılan deneyler sonucunda mikrogrid donatıların her iki temel türünün de taşıma gücü kapasitelerini arttırdığı belirlenmiştir. Ayrıca yapılan deneylerde daire kesitli mikrogridlerin ring kesitli mikrogridlerden daha iyi performans gösterdiği ve ring kesit iç çapı/dış çapı oranının değişiminin taşıma gücünde kayda değer bir artış sağlamadığı tespit edilmiştir.
During the execution stage of a construction project, several foundation issues are faced. On a construction site, the soil's natural state may not always be suitable to fully support significant structural loads. In such cases, it is necessary to treat the soil in order to increase its bearing capacity and reduce anticipated settlement. Certain ground enhancement techniques are frequently employed to enhance the bearing capacity, shear strength, settlement characteristics, drainage, etc. of subsoil. At various construction sites, ground improvement is widely recognized as a cutting-edge method of amending soil in foundations to provide improved efficacy under design and/or operational loading circumstances. Ground improvement modifies the properties of the soil, enabling various construction techniques.
Recently, an urban expansion prompted to construction of structures on weak or unsuitable ground soils. In a sustainable view, there is a need to investigate and improve such types of soils under consideration. Gypsum soil is one of the weak soils when exposed to wetness, especially the value of bearing capacity and Collapse. The main objective of this study is to carry out several model tests for gypsum soil at a relative density of 30% for dry and wet conditions under static vertical stress. The study involved evaluating the effectiveness of soil stabilization using geosynthetics reinforced (geotextile and E-glass fiber fabric) by using single, double, and triple layers placed at different locations. Soil with a gypsum content of 47% was used. Experimental tests were carried out on soil models for the dry and saturated conditions for a relative density of 30%. The ultimate bearing capacity was calculated, as well as the ratio of improvement BCR% according to the reinforcement layers. It was found that the ultimate bearing capacity increases 100% when using E-glass fiber fabric comparing used geotextile at reinforcement triple layers (0.25B+0.5B+1B) for dry state.
Geosynthetic clay liners (GCLs) are synthetic materials manufactured and widely used in geotechnical and geoenvironmental engineering due to their very low permeability and ease of use. As the most critical function of GCLs are their isolating features, it is of primary importance to precisely predict their water retention properties, especially when subjected to impure water having considerable solute concentrations because of landfill leachate. Despite numerous efforts on analytical modeling of bare soil-distilled water retention, less attention has been given to the retention characteristics of GCLs. Therefore, the current study's primary goal is to introduce a new analytical GCL-water retention model. More importantly, the selected experimental data for validation of the model comprises permeating solution with different molar concentrations along the wetting path to idealize leachate characteristics more reliably during the hydration process. The presented model is an extension of the original van Genuchten model for bare soil and pure water. The novelty of the proposed modeling approach is incorporating a new parameter, namely the pore fluid salinity index (PSI) through which, considering the influence of pore fluid chemistry on retention properties of different types of GCLs, becomes possible. The model can simply be calibrated by using a series of retention data in the presence of distilled water and one salinity level. The results also reveal the new model's robustness in capturing the retention behavior of GCLs under the influence of leachate.KeywordsWater retentionIsolating barrierLeachate chemistryLandfill
Clayey soils are widely used as barriers to control leachate leakage in landfills. Chemico-osmosis is one of the important phenomena influencing soluble contamination transport through clay barriers acting as a membrane. The membrane ability to restrict contamination transport is referred to as membrane efficiency. Experimental reports have revealed that membrane efficiency is a function of soil void ratio and contamination concentration. However, the currently used empirical function expresses the membrane efficiency simply in terms of average concentration. Therefore, the merit of this study is to enhance the reliability of this function to take into account various concentrations and void ratios for Na-bentonite soil by using the dataset reported by Malusis and Shakelford (2002). In order to highlight the significance of the newly proposed function, a numerical simulation has been conducted to compare three different approaches of applying membrane efficiency including (1) constant, (2) point, and (3) average value. The results show that membrane efficiency from the point approach is less than the constant value at shallower depths but more at deeper depths in the early years. More importantly, membrane efficiency by point and average approaches decrease over time, resulting in higher contamination concentration compared to a constant value. The implication is that current design practice based on constant membrane efficiency is not conservative. According to the results of time-dependent contamination concentration, the required thickness and an efficient lifetime of the landfill barriers should be adjusted by simulation results of more reliable point and average approaches.KeywordsContaminant transportMembrane efficiencyNumerical modellingSolute-clay interactions
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