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Conversion between static and dynamic load bearing capacity moduli and introduction of dynamic target values


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Two types of Light Falling Weight Deflectometers (LFWD) are in use in Hungary: the German device (Zorn, HMP and Wemex) and the new B & C small-plate device, which was developed by Andreas Ltd. Both devices are able to measure the dynamic load bearing capacity of subgrades, subsoils, embankment layers and backfills. Extensive application of these apparatus still has not been achieved since the dynamic modulus is not accepted in the quality assessment and quality control process of embankments and subgrade layers. Only marginal use of these devices can be noticed, mainly on areas of low importance (e.g. road shoul- ders) or trenches where performing a static plate load test could be complicated. For being able to use these dynamic devices on embankment layers, research for converting the measured dynamic modulus into static modulus has been initiated. First results of this research are presented in this paper. Using inter- national and Hungarian measurement results, required target values for Evd and Ed have been proposed for implementation.
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... Only marginal use of these devices can be noticed, mainly on areas of low importance (e.g. road shoulders) or trenches where performing a static plate load test could be complicated (Zoltán 2008). ...
... The drop weight, drop height and plate diameter are constants. The plate coefficient (c) and the Poisson's ratio (µ) are also set constant, therefore the dynamic subgrade modulus, (E vd ) is calculated by a simplified Boussinesq equation (Zoltán 2008): ...
... Some of the results show even higher ratios. Only two publications give a ratio less than two, but both of them are based on modulus values measured only at few points and within small intervals (Zoltán 2008). Nazzal (2003) present a correlation study between the PLT and the LFWD on cement treated soils, lime treated soils, unstabilizsed fine-grained soils and granular soils. ...
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The Light Falling Weight Deflectometer (LFWD) load test has been developed to directly estimate the in-situ elastic modulus of near surface profiles as foundation, and subgrade layers is presented in this paper. For this purpose, field tests were conducted on selected sections from landfill project within Anbar province. In addition, forty test sections were constructed and tested at the Civil Engineering Department-University of Anbar. All sections were tested using the ZFG 3000 model-LFWD in companion with the Plate Load Test (PLT) that were used as reference measurements. Regression analyses were conducted to determine the best correlations between the elastic modulus obtained from LFWD and PLT tests., E vd. ANN model is used to calculate dynamic deformation modulus, E vd and comparing with the regression statistical model. The results indicate that ANN model have the capability of predicting dynamic deformation modulus, E vd with a high degree of accuracy. Good correlations were obtained, which demonstrated that the LFWD can be reliably used to predict the modules obtained from plate load test and degree of com-paction values, and hence can be used to evaluate the stiffness/strength parameters of shallow subgrade layers.
... In Central Europe, quality adequacy is most often checked through static and dynamic elastic modules. The experimental measurements focused on static and dynamic plate load tests (PLT) of subsoil and road pavement subbase layers were presented by Zednik [14], Tompai [15], Elhakim et al. [16], Volovski et al. [17], Abulkareem [18], and Lehmann et al. [19]. ...
... According to [19] the correlation E v2 versus E vd is common in German engineering practice, Equation (22) shows the linear correlation proposed in FGSV:2009 (Forschungsgesellschaft für Straßen-Directive on earthworks in road construction) and for gravel in Equation (23) were performed at Technische Universität Darmstadt, Germany [53]. The next conversion between static and dynamic load-bearing capacity moduli is in [15]. The overview of linear and nonlinear (power and logarithmic) relationships between the measured static and dynamic modulus of elasticity was published in [54] (see Figure 13). ...
... According to [19] the correlation Ev2 versus Evd is common in German engineering practice, Equation (22) shows the linear correlation proposed in FGSV:2009 (Forschungsgesellschaft für Straßen-Directive on earthworks in road construction) and for gravel in Equation (23) were performed at Technische Universität Darmstadt, Germany [53]. The next conversion between static and dynamic load-bearing capacity moduli is in [15]. The overview of linear and nonlinear (power and logarithmic) relationships between the measured static and dynamic modulus of elasticity was published in [54] (see Figure 13). ...
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In the present study, credible analytical and numerical models are developed in order to explain the apparent discrepancies in the ratios of static and dynamic deformation models for assessing the quality of mechanical efficiency of transport structures in Central Europe. Through of experience, authors specifically deal with the comparison of two commonly used methods: the dynamic load plate test, known as the lightweight dynamic test and the static plate load test. This paper presents the relevant correlation dependency of the most commonly used quantification characteristics in earthworks quality control. Their correlation was obtained by applying the static theory of impact to earthworks quality control, which allows for the application of several quality control methods, in line with other member states of the European Union, specifically with regard to constructions under various boundary conditions (climate, soil moisture of the specified layer). According to an analysis of the results of comparisons of static and dynamic load tests, analytical and numerical models of the subsoil formed by soils and uncemented structural materials, respectively, the linear calculation usually used in the conditions of Central Europe does not have universal validity. Rather than relying on the analytical and FEM models for the soil, the authors have determined that the above dependence is a power dependence.
... Nazzal [26] and Tompai [46] found that the zone of influence of the LWD to vary between 1 and 2 times the plate diameter. Elhakim et al. [13] investigated the zone of influence of the LWD by performing the LWD test on calcareous and siliceous sands placed in layers with varying thicknesses resting on a rigid boundary (concrete floor). ...
... The influence of the rigid base boundary on the LWD modulus diminishes with increasing the thickness of the sand layer. For soil layer thickness to plate diameter ratios of 1.5-2, the effect of the rigid layer is considered negligible something which goes well with Nazzal [26] and Tompai [46] findings. ...
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Resilient modulus is one of the important parameters used in the analysis and modelling of subgrade behaviour and it is directly related to the safety, economic and lifetime of roads structures. The determination of Resilient Modulus (MR) using repeated load triaxial (RLT) test is expensive, cumbersome and time consuming. Therefore, a new research approach has been adopted in this study based on performing cyclic light weight deflectometer (LWD). The objective of the cyclic loading is to bring the soil to its near elastic behaviour and then measure the dynamic deformations moduli (Evd). The cyclic LWD tests were performed in the field and in the laboratory and the measured Evds values were compared to the resilient moduli measured by RLT tests conducted under similar testing conditions. The number of LWD test cycles required to bring the soil to its elastic state can be decided directly during the test by using a new multifunctional LWD manufactured solely for the purpose of this study. It has been found that the required number of LWD repetitions (cycles) to conduct Evd moduli close to MR moduli depends on many influencing factors, namely, the moisture contents, lateral confinement and the maximum vertical axial stress levels during testing. Based on this study, it can be inferred that the cyclic LWD test can be used to predict simply and quickly the resilient behaviour of the tested soil with good precision and reliability.
... One of the main requirements towards road structures is design stiffness, expressed via the modulus of deformation on the top of the road. The extra requirements for the modulus of deformation and the minimum height for the pavement structural layers are introduced as well (see, e.g. in Lithuanian Road Administration (2007), Tompai (2008)). Another aim in designing road structures is using local soils (Bheemasetti, Pedarla, Puppala & Acharya 2015;Čygas, Laurinavičius, Pauliukaitė, Motiejūnas, Žiliūtė & Vaitkus, 2015;Köhler, Herald, Hering, 1998;Lithuanian Road Administration, 2007;Mair 2005;Mateos & Soares, 2014). ...
... Such correlations for several soil types were reported in, e.g. Meanwhile, several significant investigations aimed at deriving analogous correlations of the dynamic modulus of deformation versus the static modulus of deformation have been carried out (Adam & Kopf, 2003;Bertuliene, 2011;Kopf & Erdmann, 2005;Kopf, Adam, & Paulmichl, 2005a, 2005bSchmidt & Rumpelt, 2009;Tompai, 2008;Weingart, 2003). ...
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Soil, or soil structure modulus of deformation, is one of the main design parameters for road engineering and traffic infrastructure design of, for example, highways, railways, runways and embankments. It is also the main soil improvement criterion. When creating any road structure with codified design resistance, one employs structural layers of certain thicknesses and modulus of deformation. Both values need to satisfy the minimum values in accordance with codified requirements. This paper analyzes correlations for the widely applied in engineering practice methods to determine the soil stiffness. The static test methods acknowledged to be exact enough for determining the modulus of deformation for the primary and secondary loadings. As dynamic test methods require significantly less time and financial resources, they are widely accepted in engineering practice. The dynamic methods determine only the dynamic modulus of deformation. Design practice aims to relate it with the static modulus of deformation of the secondary loading. Many countries propose codified correlations, with differing levels of conservatism, to convert the dynamic modulus of deformation into the static one. Developed correlations between the results of the static plate load test and the dynamic plate load tests processed from own test results of different soils are presented and a comparative analysis with other proposed correlations is given.
... An area of 7.5 m in length and 1 m in width was selected in the field implementation for detailed studies. As shown in Fig (Tompai, 2008;Mikolainis et al., 2016;Fei et al., 2021). In this work, the GTJ-EVD apparatus ( ...
A B S T R A C T A suitable bearing capacity of foundation is critical for the safety of civil structures. Sometimes foundation reinforcement is necessary and an effective and environmentally friendly method would be the preferred choice. In this study, the potential application of enzyme-induced carbonate precipitation (EICP) was investigated for reinforcing a 0.6 m bedding layer on top of clay to improve the bearing capacity of the foundation underneath an underground cable duct. Laboratory experiments were conducted to determine the optimal operational parameters for the extraction of crude urease liquid and optimal grain size range of sea sands to be used to construct the bedding layer. Field tests were planned based on orthogonal experimental design to study the factors that would significantly affect the bio-cementation effect on site. The dynamic deformation modulus, calcium carbonate content and long-term ground stress variations were used to evaluate the bio-cementation effect and the long-term performance of the EICP-treated bedding layer. The laboratory test results showed that the optimal duration for the extraction of crude urease liquid is 1 h and the optimal usage of soybean husk powder in urease extraction solution is 100 g/L. The calcium carbonate production rate decreases significantly when the concentration of cementation solution exceeds 0.5 mol/L. The results of site trial showed that the number of EICP treatments has the most significant impact on the effectiveness of EICP treatment and the highest dynamic deformation modulus (Evd) of EICP-treated bedding layer reached 50.55 MPa. The area with better bio-cementation effect was found to take higher ground stress which validates that the EICP treatment could improve the bearing capacity of foundation by reinforcing the bedding layer. The field trial described and the analysis introduced in this paper can provide a practical basis for applying EICP technology to the reinforcement of bedding layer in poor ground conditions.
... The elastic modulus can be derived from some tests in the laboratory, including the triaxial compression test, 1-D consolidation test, oedometer test [9], and unconfined compressive strength test. In the case of on-site tests, the elastic modulus can be deducted from the standard penetration test (SPT) [10], dynamic penetration test (DPT) [11], and plate bearing test (PBT) [7,12]. The elastic modulus estimations via a triaxial compression test and an oedometer test in a laboratory are applicable for fine-grain or cohesive soil, where the largest grain is smaller than the mold diameter by 15 or 20 times as specified in ASTM D5321/D5321M-21. ...
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In this paper, the moduli of elasticity of compacted loess and lateritic-loess soils on-site were estimated from the laboratory test. These were coarse grain soils used for the construction of base course and embankment of the railway line. The knowledge of the soil properties on-site such as the compacted elastic moduli is essential for the design and selection of materials. A total of 108 samples consisting of 36 samples of compacted soils on-site and 72 samples of compacted soils in laboratory were tested using plate bearing tests. The water contents of the compacted soil on-site were controlled to be within ±2% of optimum water content. The water content and density of compacted soil on-site were determined and used for the compaction of soils in the laboratory. For the testing in laboratory, two loading types viz., point load and uniform load were performed using the compacted 15-cm diameter mold (California Bearing Ratio). The results showed that the point load test gave a slightly better estimation of elastic modulus with R² of 0.977 than the uniform load test with R² of 0.970. The experiment showed that the on-site elastic moduli of loess and lateritic-loess soils could be accurately estimated from the laboratory load tests.
... The dynamic devices that are most often used for checking the quality of loose soil compaction were invented in the late 1970-ies (Tompai 2008). The thickness of the tested soil layer depends on the diameter of the plate of the device, i.e. the bigger the diameter, the thicker the tested layer is (Tirado et al. 2015;Koukoulidou et al. 2017). ...
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The surface of earth on the territory of Lithuania is covered by sediments of the Quaternary system, which are the object of human economic activities. Reliable assessment of sediment deformations is an important task of modern engineering geology and geotechnical engineering. The deformation of sediments is most often described using the modulus of deformation. The current article overviews different methods employed in deformation moduli determination and their application possibilities. The deformation moduli, which are used in various calculations, are usually calculated using correlation formulas and empirical coefficients. Thus, the obtained results may be inaccurate or completely unsuitable for further interpretation of the numerical situation. This article presents recommendations with regard to the use of various calculated deformation moduli in interpreting Lithuanian Quaternary system sediments.
Building of an experimental slope protection system on Căpuş river, near Cluj presented the opportunity of in situ testing of stabilized soils. Different hydraulic binder was used on each side of the river, so this testing series provided valuable data about deformability properties of the encountered soil types. There are some deformability parameters used in Romania which were “imported” at the specific request of foreign investors. The strain modulus, E v , is a parameter expressing the deformation characteristics of a soil and is calculated taking values from the load-settlement curve obtained from the first and second loading cycle, on a static plate load test. In earthworks, the dynamic plate load test using the Light Falling Weight Deflectometer may be used for testing load-bearing capacity as an alternative to the static plate load test which provides the strain modulus, E v parameter. Dynamic modulus of deformation E vd is a parameter for the deformability of soil under a defined, vertical impact load with the impact duration. Its value is being calculated with the maximum settlement of the load plate. None of these methods made way into official Romanian standardisation, the E vd is subject of a technical agreement, which also contains the correlation of it with E v . Conducting both static and dynamic loading tests enabled the verification of validity of relation between strain modulus and dynamic modulus.
Evaluation of the strength and stiffness of compacted geo-materials is required to ensure that it has sufficient bearing capacity and stiffness to the acting loads. In this study, a crosshole-type dynamic cone penetrometer (CDP) was applied to investigate the strength and stiffness characteristics of a compacted subgrade. The CDP characterizes the subgrade strength by the penetration index (CDPI) and evaluates the stiffness by the shear wave velocity (Vs) and maximum shear modulus (Gmax). CDP tests were conducted at three testing points. Repetitive plate loading tests (rPLTs) and light falling weight deflectometer (LFWD) tests were conducted as standard testing methods for the stiffness estimation of the subgrade. Experimental results show that while the rPLT and LFWD evaluate the equivalent elastic moduli (Ev1, Ev2, and Evd) within the influence zone, the CDP provides the CDPI, Vs, and Gmax along the depth. Linear relationships between the Gmax and the equivalent elastic moduli are constructed. The strain levels corresponding to Ev1, Ev2, and Evd are estimated. This study demonstrates that the CDP is an effective testing method for both strength and stiffness evaluations of the subgrade along the depth.
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In order to evaluate material characteristics (in situ modulus) of well-compacted subgrades, the portable falling weight deflectometer (PFWD) test, which simulates dynamic loads, was adopted. The falling energy was assumed as a dynamic load and a well-compacted subgrade was treated as an ideal elastic body. In addition, the static plate-bearing load test (PBLT) was used to evaluate the coefficient of subgrade reaction. The PFWD test and PBLT for a total of 22 testing points were carried out on well-compacted subgrades at two different highway construction sites (A and B). Three falling heights and weights were used to produce six different levels of dynamic loads. The test results show that there is a reasonable linear correlation between the dynamic deflection modulus and the coefficient of subgrade reaction of well-compacted subgrades. It was also found that the dynamic deflection modulus is not largely affected by variation of the falling energies. Application of the PFWD for compaction control and as an alternative method to the PBLT would lead to significant cost savings.
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