Nahla Salim

• PhD in Geotechinc
• Professor at University of Technology - Iraq

The purpose of this study is to demonstrate how variations in soil suction impact shear strength, swelling pressure, and volume changes. To that end, small-scale tests were conducted on both pure bentonite and bentonite in mixtures of 30%, 40%, and 50% with sand under dry conditions, using values selected from compaction curves. A model with dimens...

When piles are used to reduce raft settlement, significant shear stresses and bending moments can be created. Separate piles are utilized to alleviate concerns about high tensions in piles and rafts. A structural fill sand-gravel cushion in an unconnected piled raft foundation isolates the piles from the raft (UCPR). The cushion redistributes the l...

When piles are used to reduce raft settlement, significant shear stresses and bending moments can be created. Separate piles are utilized to alleviate concerns about high tensions in piles and rafts. A structural fill sand-gravel cushion in an unconnected piled raft foundation isolates the piles from the raft (UCPR). The cushion redistributes the l...

When piles are used to reduce raft settlement, significant shear stresses and bending moments can be created.Separate piles are utilized to alleviate concerns about high tensions in piles and rafts. A structural fill sand-gravel cushion in an unconnected piled raft foundation isolates the piles from the raft (UCPR). The cushion redistributes the lo...

Developing countries industrial growth necessitates innovative machine foundation design and resilient infrastructure. Meanwhile, soil properties play a significant role in the satisfactory design of machine foundations. The paper presents an experimental work to determine accurately the damping ratio and shear modulus by equations. The paper studi...

Thirty-seven physical models were performed, with saturated clayey soil mixed with recycled tiers chips and stabilized by 2% of cement, to investigate the effect of clay-granulated rubber mixtures on the static response of a foundation resting on it. Three percentage of tiers chips were used 4%, 8%, and 12%. Different parameters were taken into con...

The book includes more than 200 problems in Soil Mechanics

The stone column technique is an effective method to increase the strength of soft cohesive soil, which results in a reduction in foundation settlement and an increase in bearing capacity. The topic of restraining creep settlement through the use of stone columns techniques has gained increasing attention and consideration; because stone columns ar...

Piled rafts are widely used to provide the foundations for high-rise buildings with a high bearing capacity and exhibit accept�able settlement characteristics. A high level of axial stress is created in the few piles that are structurally attached to the raft when piles are utilized as settlement reducers in piled raft foundations. Unconnected pil...

Helical piles are a kind of foundation that can withstand compression, tension, and lateral stresses. However, this kind of pile was utilized extensively globally for almost 25 years. Its behavior, particularly in Iraq, is uncertain and frightening. The current research used the finite element technique to analyze this kind of pile. The helical pil...

The difficulty that arises in the design of a machine foundation is how to know the behavior of the soil at different soil conditions. Therefore, there are many indications of a need to study machine foundation on soil of different degrees of saturation, covering all the important aspects of clay soil. Experiments on machine foundation (circular an...

The tests were conducted in poorly graded sand prepared at three relative densities. Different parameters were considered such as method of installation, relative density, removal of soil plug, pile length to diameter ratio, and the ratios of friction and end resistance contribution with respect to ultimate bearing capacity. It was concluded that t...

The stone column technique is an effective method to increase the strength of soft cohesive soil, which results in a reduction in foundation settlement and an increase in bearing capacity. The topic of restraining creep settlement through the use of stone columns techniques has gained increasing attention and consideration; because stone columns ar...

Piles with helices are a kind of foundation that is capable of withstanding compression, tension, and lateral loads. However, for almost 25 years, this kind of Pile was widely used across the world. Its behaviour is unpredictable and terrifying, especially in Iraq. The present study analysed this kind of Pile using the finite element method. It was...

Over the past few decades, interest has grown about the role of the piled raft structure in soils. A structural fill cushion separates the piles from the raft in the form of an unconnected piled raft base (UCPRF). Given the advantage of this structure, the load is dispersed between the raft and the piles by the cushion. The cushion serves as a load...

Most of the studies of laterally loaded piles focused on the behavior for piles subjected to static or cyclic lateral loading embedded within dry or saturated soils, few studies investigate the behavior of piles embedded within partially saturated soils and subjected to dynamic loads. In this research, an experimental study presents an aluminum pil...

Helical piles have many properties over the other types of piles systems include high tensile capabilities, the possibility of fast installation, applying load immediately after installation, and suitability for most soil's condition. In addition to that, helical piles have relatively less noise during installation; they represent a cost-effective...

The knowledge of the stress distribution and displacements that occurred in and around the openings is required for the safe design and construction of underground structures. The effect of geogrid reinforcement on the transfer of dynamic load to the underground structure is the subject of this research. Within the soil, a PVC pipe was used to repl...

To investigate the effect of the changes of the soil suction on volume changes, small-scale experiments were conducted for pure bentonite and bentonite mixed with sand of proportion 30%, 40%, and 50% at different initial water contents and dry unit weights that were chosen from the compaction curves. In addition, a large-scale model with soil dimen...

Helical piles provide many advantages over other conventional piles system. Most studies focuses on the performance of these piles in the dry and fully saturated soils. Rare studies are curried out to evaluate the performance of helical piles in partially saturated soils. Small scale models of steel piles of 600mm length with single, double, and tr...

A finite element formulation for the static, cyclic, and dynamic analyses of the laterally loaded single pile model embedded in sandy soil was carried out. The sandy soil was brought from Baghdad; the state of soil changes from dry, saturated, and unsaturated conditions. The analysis was performed by using “ABAQUS 3D V.6.14”. The program validity w...

A machine foundation is considered important due to that the foundation design under dynamic loads must be governed by serviceability limit states performance considerations rather than strength requirements. The dynamic response is carefully calculated to ensuring high-quality and efficient performing for machinery. This paper presents a model for...

This test program studies the impact of using fly ash on prepared soil by adding different percentages of fly ash (5%, 10% and 15%) by dry soil weight. The expansive soil was prepared in the laboratory by mixing natural soil (Al-Nahrawan clayey soil) with different percentages of bentonite (30%, 50% and 70%). The experimental study focuses on the e...

Helical piles are foundation systems used to support compression, tension, and lateral loads. However, this type of piles was used around the world for more than 25 years. Its behavior, especially in Iraq, is still unknown and scare. The present study is carried out by analyses of this type of pile using the finite element method. Modeling of the h...

Many researchers’ studies have shown that stone column is the best material to use to improve the bearing capacity of clayey soils. There are millions of waste volumes resulting from daily human activities. This excess waste leads to disposal problems and also causes environmental contamination and health risks. Demolished concrete is such one wast...

Steel H-piles are applicable to many different geological deposits. They are the preferred foundation choice in terms of cost. It can withstand high driving stresses and have good resistance to buckling. Since a few researches are available about H-piles, therefore this research introduces an experimental study to evaluate compression bearing capac...

This work focuses on the effect of construction and loading of piles group on an existing tunnel. This was achieved by performing model tests on a sandy soil using two relative densities (50% and 70%). The experimental models include group of piles (2×1) with 3d spacing and (2×2) with 3d and 8d spacing. Three clear distances between the pile and th...

Simulating for wave spread in geomechanics can be considered as an important subject within dynamic analysis. Chiefly, studying the soil-foundation interaction represents a stimulating matter in geotechnics studies. This paper presents the development of a reliable and efficient technique for the numerical simulation of unbounded domain (the semi-i...

Artificial soils were prepared by mixing kaolinite with different percentage of organic material (animals waste) represented by 5, 10, 15 and 20% of soil dry weight. Series of Standard tests were conducted to determine the physical and mechanical properties of the soil such as, Grain size distribution of soils, Atterberg limits, soil compaction, va...

It is essential to measure the response of existing tunnel-lining due to newly constructed pile to assess the safety against the additional forces/moment caused by pile driving and loading and to evaluate the critical distance for the proposed construction of any structures from the tunnel location. This study presents an experimental work to inves...

This study comprises experimental tests that consist of 138 tests that are divided as follows: 36 tests for single pile, 36 tests for pile group (2 × 1), 36 tests for pile group (2 × 2) and 30 tests for pile group (2 × 3). All tubular piles are tested in poorly graded sand. Different parameters are considered such as the method of installation, rel...

Abstract. Soil stability plays a vital rule in projects’ infrastructure such as embankment, retaining walls dams and highway. Structure built on soft soil may experience uncontrollable settlement and critical bearing capacity. This may not meet the design requirements for the geotechnical engineers. Soil stabilization is a process to change such un...

In this paper, a rigid circular foundation with diameter of 150 mm is subjected to two modes of vibration each mode applies with two frequencies. The foundation was placed at three different depths within dry sand with two relative densities in a test model with dimensions of (800 × 800 × 1000) mm. A total of 18 models have been tested to study the...

In this study, a series of 24 laboratory tests were conducted on a footing resting on crushed stone with 17.68 kN/m ³ dry unit weight overlying sandy soils of two relative densities corresponding to (60% and 80%). The subbase layer is of crushed stone with a thickness of 5, 7.5 and 10 cm. Ten tests were conducted under static load with and without...

In the past decades, great efforts were spent to understand the behavior of laterally loaded piles in unsaturated soil. The main property of unsaturated soil is the ability to store and release water and introduce capillary zone which increase the soil resistance. Since the unsaturated soil above the water level is governed by two independent stres...

Soft clay may experience uncontrollable settlement and loss of critical bearing capacity due to the fact that clayey soils possess remarkable plasticity which increases moisture retention and causes decreases in strength, volume changes, and loss of compressive strength. Thus, these types of soils need to be improved before use in construction. A h...

Plugging is essential not only due to its direct contribution to pile end load carrying capacity but also due to its indirect contribution to mobilised shaft capacity. A pile with a plug displaces more soil than a pile that penetrates in boring mode, which enlarges the effective stresses around the pile. Numerical modelling of plugged pipe piles wa...

Formation of a soil plug in an open-ended pile is a very important factor in determining the pile behavior both during driving and during static loading. The degree of soil plugging can be represented by the incremental filling ratio (IFR) which is defined as the change in the plug length to the change of the pile embedment length. The experimental...

All structures built on soft soil may experience uncontrollable settlement and critical bearing capacity. This may not meet the design requirements for the geotechnical engineer. Soil stabilization is the change of these undesirable properties in order to meet the requirements. Traditional methods of stabilizing or through in-situ ground improvemen...

Liquefaction is a physical process by which, soils lose their shear strength, liquefaction occurs in loose saturated granular soil due to applying dynamic loads. This paper presents and discusses the results of 54 experimental model tests, all of them were performed on saturated sand under vertical dynamic traffic load prepared at different relativ...

Open-ended steel pipe piles are widely used for foundations both on land and offshore. During driving process of these piles into the soil, a soil column known as the soil plug is formed inside the pile. As the penetration continues, the frictional resistance between the inner pile shaft and the soil plug maybe developed and in turn may prevent fur...

To investigate the effect of the changes of the soil suction on volume changes, expansion index and swelling pressure, large scale model with soil dimensions (700*700*650) mm was used to prepare the soil samples at the same initial water content and dry unit weight to show the effect of water content changes on different relations (swelling with ti...

Soft clay may experience uncontrollable settlement and critical bearing capacity due to the fact that clayey soils poses a remarkable plasticity which increases moisture and causes decreasing its strength, volume change and compressive strength so this type of soils need to be improved. Furthermore, there is millions of waste volumes results from d...

Liquefaction is a phenomenon that occurs during earthquakes, and leads to ground failure. Water-saturated, well sorted, fine grain sands and silts behave as viscous fluid as a result of liquefaction. This behavior of fluids is very different than solids behavior. This paper presents and discusses the results of 54 experimental model tests, all of t...

Now a day the urbanization required to construct a high rise building which needed a deep foundation (piles) and this may be close to existing infrastructure such as subway, tunnels etc. Construction and loading of pile cause a significant effect in terms of stresses and deformation. The tunnel owners used restrictive guidelines for the constructio...

Open-ended steel pipe piles are widely used for foundations both on land and offshore because of low cost compare with other types of piles and it does not need a high effort for driving. During driving process of these piles into the soil, a soil column known as the soil plug is formed inside the pile. As the penetration continues, the frictional...

To investigate the effect of the changes in the soil suction on volume changes, expansion index, swelling pressure, shear strength and the coefficient of permeability, small-scale experiments were conducted on pure bentonite and bentonite mixed with sand with proportions of 30, 40 and 50% at different initial water contents and dry unit weights tha...

To investigate the effect of the changes of the soil suction on volume changes, laboratory experiments were conducted on pure bentonite and bentonite mixed with sand of proportion: 30, 40 and 50% at different initial water contents and dry unit weights that were chosen from the compaction curves. In addition, large-scale model with dimensions (700...

Underground facilities are an integral part of the infrastructure of modern society and are used for a wide range of applications, including subways and railways, highways, material storage, and sewage and water transport. Underground facilities built in areas subject to dynamic activity must withstand both dynamic and static loading. This study fo...

The experimental tests contain 36 tests carried out on single piles. All tubular piles tested by using the poorly graded sand from the southern city of Karbala in Iraq. The sand was prepared at three different densities using a raining technique. Different parameters are considered such as method of installation, relative density, removal of soil p...

Expansive soils are generally found in arid and semiarid regions. These soils undergo volumetric changes upon wetting and drying, thereby causing ground heave and settlement problems. This characteristic causes considerable construction defects if not adequately taken care of. Solving the unsaturated soil problems needs the assessment of suction va...

Abstract: Construction of embankments over soft clay is a great challenge because these soils may be too weak to support the entire load of an embankment. The analyses were carried out to review and estimate the excess pore water pressure, the total and rate of consolidation settlement in embankments constructed on soft soils. Methods of improving...

In this paper, a dynamic analysis of strip machine foundation is carried out. The foundation of multiple thicknesses is placed at different depths above a saturated sand with different states (i.e. loose, medium and dense), and vertical harmonic excitation is applied with build up of the excess pore water pressure being considered. The dynamic anal...

The behavior of machine foundation on saturated porous medium can be considered as a complicated geotechnical problem due to nature of dynamic loads and plasticity of soil which make the analysis and design of foundation subjected to dynamic loads more complex. The main criteria for safe performance of machine foundations subjected to dynamic loads...

This paper focuses on the effect of machine vibration on the variation of excess pore water pressure and settlement of saturated sand. A special setup is designed and manufactures to simulate the vertical vibration of the machine. A total number of 36 model tests are conducted on sand using three relative densities (35, 60 and 85%) representing loo...

The mechanical behavior of partially saturated soils can be different from that of fully saturated soils. It has been found that for such soils, changes in suction do not have the same effect as changes in the applied stresses, and consequently the effective stress principles is not applicable. A finite element analysis was carried out on a single...

In this study, the stresses around a tunnel during construction stages are discussed. For this purpose, the finite element method (FEM) was adopted as an effective approach to analyze the problem using (SIGMA/W) program. The research includes the study of the behavior of soil due to excavation of tunnel by calculating the displacements and stresses...

When a tunnel is excavated in fully saturated soil, two types of time dependent behaviours occur in the surrounding ground. The first comes from the intrinsic rate dependent characteristic of the material such as creep deformation or stress relaxation and the second is caused by the loss of apparent strength of material due to dissipation of the ex...

The effect of construction new tunnel on nearby tunnel was investigated using finite element software program SIGMA/W. Two methods of excavation were used, one using one stage in construction of tunnels and the other using eight stages of excavation. The analysis also carried out to study the effect of nearby tunnel on existing tunnel by varying th...

Surface settlements of soil due to tunneling are caused by stress relief and subsidence due to movement of support by excavation. There are significant discrepancies between empirical solutions to predict surface settlement trough because of different interpretations and database collection by different authors. In this paper, the shape of settleme...

T h e present research aims to study the stresses analysis through construction stages of the underground structures (Tunnels). For this purpose, the finite element method (FEM) was adopted as an effective approach to analyze the test results using (SIGMA/W) program. The research includes the study of the behavior of soil due to excavation of tunne...

A tunnel is not only stabilized by safety measures e.g. steel and concrete. The surrounding underground is part of the construction. The excavation of an underground opening influences the stresses around the tunnel. Therefore twin tube highway-tunnels are excavated in a distance 40 m. When the designed tunnel meets ex isting underground structures...

The problem of the proposed "Baghdad metro line" which consists of two routes of 32 km long and 36 stations is analyzed. The tunnel is circular in cross-section with a 5.9 m outer diameter. The finite element analyses were carried out using elastic-plastic and modified Cam clay models for the soil. The excavation has been used together with transie...

Surface settlements of soil due to tunneling are caused by stress relief and subsidence due to movement of support by excavation. In this paper, the shape of settlement trough caused by tunneling in cohesive ground is investigated by different approaches; namely, analytical solutions, empirical solutions and numerical solution by the finite element...

The analyses of tunnels in clay were carried out taking into consideration two great important and effective categories, the time independent and time dependent. Time independent behaviours are used to represent the excavation stage while time dependent analyses are used to represent the behaviour of the unlined tunnel after a long time. The finit...