Piles

Two trial piles were installed at the berm section of an embankment in the later stage of its construction and one of them was fitted with an oversized casing to isolate its top 3. m from the action of surrounding soil. Lateral bending behaviour these two piles subjected to passive sub soil movements were very different from each other because of the casing and is modelled in this paper using a three dimensional analysis. The effect of relative stiffness of the piles on their lateral bending behaviour is investigated. The effect of interface joint slip on the pile's behaviour is also investigated in a later section of this paper. © 2013 Elsevier Ltd.

http://www.sciencedirect.com/science/article/pii/S0266352X13000591

Although techniques have been developed for prediction of lateral loading response of foundation piles for offshore structures,most of the attention to axial behavior bas been focused only on consideration of ulti­mate load capacity. The field data to sup­port predictive methods is inadequate , being limited primarily to load settlement tests which report only the response at the head of the pile. In the vast majority of cases in offshore operations , the performance of load tests is prohibitively expensive . A reason­ably satisfactory method to predict pile-bead response is critically needed . Various  aspec ts of the total problem include (1) de­termination of soil properties,(2) predic­tion of soil reaction versus pile displacement in various soisl at various depth ,

This paper presents an evaluation of interpretation criteria for deep foundations under axial compression loading. Static load test data on driven PC pile, pre-bored PC pile, and drilled shaft under drained and undrained conditions were subjected to various interpretation criteria and used to examine the relationships of load-displacement behavior of different pile types. The general trend of each interpretation method demonstrates similarity for all pile types. In all events, DeBeer method is the lower bound criterion and Chin method is the upper bound and is always above the measured data. The normalized load-displacement curve of drilled shaft in gravelly soils shows great ductility whereas the curve of driven pile in drained soils exhibits a stiffer response. Based on these analyses, the interrelationships of these criteria for different pile types under drained and undrained soils are established in terms of normalized capacity and displacement.
Keywords: interpretation criteria, driven piles, pre-bored PC piles, drilled shafts, drained soils, undrained soils, gravelly soils

This paper examines the impact of different pile configurations and geometric parameters on the bearing capacity and the settlement response of a combined pile–raft foundation system utilizing FLAC3D software. The configurations considered were: (1) uniform piles (denoted as CONF1), (2) shorter and longer piles uniformly distributed on the plan view of the raft (CONF2), (3) shorter piles at the center and longer piles at the edge of the raft (CONF3), and (4) longer piles at the center and shorter piles at the edge of the raft (CONF4). In the same framework, different pile diameters and raft stiffnesses were examined. The piles are considered to float in a cohesive–frictional soil mass, simulating the thick cohesive soil deposit found in Addis Abeba (Ethiopia). During simulation, a zero-thickness interface element was employed to incorporate the complex interaction between the soil elements and the structural elements. The analyses indicate that the configuration of piles has a considerable effect on both the bearing capacity and the settlement response of the foundation system. CONF1 and CONF3 improve the bearing capacity and exhibits a smaller average settlement than other configurations. However, CONF3 registers the highest differential settlement. On the other hand, the lowest differential settlement was achieved by the CONF4 configuration; the same configuration also gives ultimate load resistance comparable to those provided by either CONF1 or CONF3. The study also showed that applying zero-thickness interface elements to simulate the interaction between components of the foundation system is suitable for examining piled raft foundations problem.

Integral Abutment bridges (IAB’s) can be defined as bridges without joints. The main purpose of constructing IAB’s is to prevent the corrosion of the structure due to water seepage through joints. The biggest uncertainty in the design of these bridges is the reaction of the soil behind the abutments and next to the foundation piles, especially during thermal expansion. This lateral soil reaction is nonlinear and is a function of the magnitude and nature of the wall displacement.To gain a better understanding of the mechanism of load transfer due to thermal expansion, which is also dependent on the type of the soil adjacent to the abutment walls and piles, a 3D finite element analysis is carried out on representative IAB. In this paper two models are compared one with considering soil interaction and other without soil interaction and live load is applied using STAAD-Beava. The main objective is to study the trends in bending moment, shear force and deflection in central and end long...

Firstly, I want to thank you because you have decided to buy this book, namely Concise Edition: Pile Foundation Basics.

This book is not as great, nor is it comparable to other Pile Foundation related books. What I can say, this book was written to facilitate understanding and to help readers deepen their knowledge of the Pile Foundation.

This is because not all books are suitable for readers. Even with the same title, however, there are some books that go so far that they interfere with the main purpose of delivering the message.

As such, I take a different approach by reducing unnecessary, lengthy, and sparse sentences. The book is therefore readable to all readers of all ages.

Concise Edition: Pile Foundation Basics is the result of my 10 years of experience in engineering and geotechnical. It's a book with a simple story, about what the Pile Foundation is, what type of pile and material it uses, and what the basics and methods of estimation are.

What I hope for is, even though this book is a bit scholarly, but it will definitely benefit you, whether you are a student, teacher, engineer or whatever career you are pursuing.

The rapid growth in the demand for floor space for both residential and commercial needs has forced the developers to go for tall and heavily loaded structure irrespective of the supporting soil conditions. Even under the most unfavorable soil conditions tall structures have been constructed with appropriate foundation systems. Under such unfavorable circumstances deep pile foundations are adopted to support tall and heavily loaded structures. Deep pile foundations designed to carry the structural load to the bearing strata so that the serviceability and ultimate conditions are satisfied. The prediction of pile capacity prior to the initial load test has always been a challenge for the designers of consultants and the specialist agency executing the piling, due to the evaluation of in-situ parameters from the laboratory tests conducted on the undisturbed samples obtained from the soil investigation. Therefore assessing the initial test load becomes very difficult for both the consultants and the specialist contractor. Hence the prediction of the load settlement response and the most probable capacity of the pile is a requirement so that the kentledge load can be assessed. In the initial stages it can be assumed that the load settlement response of the pile loaded to failure will exhibit hyperbolic behavior. Chin (1970) has developed the method which has been widely adopted, although it is well known that the method has not been linked with soil parameters, but used as a method for predicting ultimate load of the pile not tested to failure. Most of the time pile load tests are not carried out upto failure. This necessitates a predictive analytical procedure to arrive at the ultimate load of the pile or pile group. Generally the load-settlement response of a single pile and piled-raft are expected to be hyperbolic. When the inverse stiffness is plotted against the settlement, the inverse of the slope gives the failure load or the stress. This prediction is very useful in assessing the failure load of the foundation system. In practice the stress-strain characteristics based on triaxial test also shows a hyperbolic behavior. A series of tri-axial tests were conducted on poorly graded sand obtained from a local source for determining the stress-strain behavior under different density condition and confining pressure. The necessary characterization of the samples was carried out with the grain size analyses. Prior calibration was done to pack the sample under three different density conditions namely loose, medium dense and dense conditions. From the stress-strain characteristics, hyperbolic constants were found out by converting the stress-strain plot into a hyperbolic plot. For getting the load-settlement behavior of pile and piled raft 1g model test was conducted on the pile and piled raft on a bed of sand prepared under the same density conditions. The load settlement response obtained from the 1g model tests was converted into a hyperbolic plot using Chin's method, and the hyperbolic constants were obtained and were compared

Using piles in the foundation had escalated as the number of high-rise buildings had increased through the past years. The main purpose of piles is to transmit loads from shallow weak layers to deeper and stronger layers of soil. That type of foundations is used to fulfil both bearing capacity and settlement control requirements. The pile group bearing ultimate load and pile group settlement are affected by many factors such as the pattern of piles, the piles diameter, the piles length, the spacing between piles and the surrounding soil type and state. The behaviour of the group of piles is completely different from that of a single pile. In this paper, The behaviour of the groups of piles under vertical loads in overconsolidated clayey soil is studied using advanced numerical modeling and compared with the behaviour of the single pile at a well-documented case history. KEYWORDS Group of piles, pile group action, pile group efficiency, settlement of group of piles, overconsolidated clay.

Foundation is one of the most important part of any structure to transfer the load from superstructure to the underlying materials such as soil, rock or seabed. The foundation holds a structure firmly to prevent it from lateral movement of the supporting material. It is done by ensuring the structure held securely to the ground to avoid it from sinking into the ground and being blown away. The problems that encountered during the installation of piles are not taken into account in the early of the design. The possibility of exposing inaccurately driven piles at any construction is high. Therefore, this study is carried out to analyse the pile cap due to eccentricity and pile failure. It focuses on the possibility to reduce the effect of high eccentricity by increasing the number of piles and drive them in the ideal position. Besides, it also concentrates on the reanalyse of the pile eccentricity and pile failure which focus on the number of replacement pile to be installed at the most ideal position while taking the effect of eccentricity into consideration. Therefore, the main aim of this research is to figure out of solving the reanalysis of pile cap due to pile eccentricity and pile failure that occurs at site by developing an excel program. The result of this study is to develop a chart that can be used at site to locate the additional or replacement of pile in the most appropriate location which could bring back the centroid of all piles to the original centroid as much as possible.

There are many equations available in the literature using the results of CPT (cone penetration test) and SPT (standard penetration test) measurements to predict the end bearing capacity of drilled shafts in sand. However, there are few equations that use soil parameters, such as friction angle and elastic modulus, as input values. Also, these available equations usually overestimate the end bearing capacity, and at times show conflicting results with respect to the parameters they use. This paper describes a numerical procedure to overcome the above shortcomings. The results obtained in this study were compared with both experimental and numerical results available in the literature. A series of analyses is also conducted to assess the effects of various soil and pile parameters on the magnitude of end bearing capacity of piles embedded in sand. These parameters include diameter and length of pile, friction angle, and Poisson's ratio of soil. Based on the numerical analyses carried out in this study, a new equation is proposed to estimate the end bearing capacity of drilled shafts in sands. The results of the proposed equation are also compared with experimental data available in the literature on end bearing capacity of drilled shafts. The comparison shows better agreement of the suggested end bearing capacity equation with respect to other previously proposed methods.

The piled-raft foundation systems have started to be a very popular design method that is commonly used for especially high-rise buildings. In this foundation system, both raft and piles share the applied loads coming from the supper structures. There are several methods proposed by researchers in order to solve piled-raft foundation problems by simplified methods, approximate methods, and more sophisticated computer-based methods. These sophisticated computer-based solutions are not simply adapted to geotechnical works, and accessing these programs by everyone is not easy. The main purpose of this study is to present an easy and new technique for solving piled-raft problems with using 2D-FEM analysis combined with equivalent pier. In this study, design concepts of a pile-raft system prepared by 2D-FEM analysis combined with equivalent pier were presented. Furthermore, the test results obtained from this method were compared with the results that were taken from equivalent raft method and equivalent pier with single pile response in a sandy soil. A generic example of a piled-raft system including 3 × 3 number piles was designed, and its some properties such as length of pile (10-28 m), pier-soil stiffness ratio (1000-5000), and spacing between the piles (2-4 m) were evaluated and compared as variables. It was concluded from this study that equivalent pier with 2D-FEM analysis can make very similar predictions for calculating settlements of piled-raft system regarding on equivalent pier with single pile response method. As a result of this study: (1) as aspect ratio of piled-raft system increases, raft to pile stiffness ratio gradually increases for all s/d ratios, (2) the efficiency exponents obtained from this study ranges between 0.46 and 0.58 values, (3) stiffness of the piled-raft system gradually increases with increase of slenderness ratio for both two equivalent pier methods, and (4) as slenderness ratio increases, stiffness ratio of the piled-raft system contrarily decreases.

A Large diameter bored pile with diameter of 1.00 m and length of 34.00 m has been implemented in multi layered soil. The pile was tested under three axially loading and unloading cycles, in order to determine the load settlement curve and assess the ultimate pile capacity. Extensive investigation was carried out to obtain reliable soil properties at the examined pile location, through in situ and laboratory soil tests. Twelve strain gauges were fixed on pile steel reinforcement bars at top of each soil layer level. Moreover, four dial gauges were set up at pile head. Also, three telltales were extended to three different levels inside the pile. The pile load test field measurements are presented in the form of load settlement and load distribution curves for different loading steps. In addition, the pile ultimate capacity is calculated using different codes criterions and compared with the loading test results.

This study presents an innovative procedure to derive the ultimate load capacity of a pile system by considering the natural (intrinsic) variability of a tropical soil. The tropical soil has high aluminum and iron content due to processes of lixiviation of the upper soil layers. As a consequence, this soil has a porous cemented structure, high void ratio, high permeability, and high variability of the geotechnical parameters in its depth. Soil layers are experimentally characterized via standard characterization, a triaxial test, standard penetration test, and flat dilatometer tests. Also, the load test of the standard groups (PG) and pile plus pile-cap (PC), which had self-drilling piles, were performed at real scale. Afterwards, simulations using a three-dimensional finite-element method (3D FEM) considering variations in soil parameters were performed for a hypothetical piles-plus-pile cap system under vertical loading using the random finite-element method. Mean parameters were verified through laboratory and field tests. Results from the load test simulations were compared with real-scale tests conducted in this study. The relative importance of variability of several geomechanical parameters was analyzed in terms of their effects on the contribution of the pile cap to the ultimate bearing capacity of the full system and found to be 18%; the minimum contribution is 2% of the total load. Finally, it is shown that reasonable savings in construction costs accompanied by a modest reduction in the safety factor (FS = 1.8) may occur when the variability of parameters is taken into account.

The paper attached contains a video link where detailed analysis and design of acid tank in an industry is provided using both manual calculations and using FEM software MIDAS Gen. The detailed load calculations, analysis and design is illustrated from beginning to end by me. I am  hopeful that it will be serving as a guide for practicing and student engineers as well as a guide for teaching professionals.

This paper presents the experimental study of Soil-Cement Pile (SCpile) by wet mixing method in sandy soils, with the typical project at An Trung Complex apartment, Da Nang city, Vietnam. With the characteristic of soil layers is sandy soil, the strength of laboratory stabilized soils with the amount of cement from 150300 kg/m 3 was determined. Simultaneously, the authors also performed the experiments of 20 test piles collected from the site which has cement content about 280 kg/m 3 and the unconfined compressive strength qu= (4.56.0) MPa. After that, a full-scale model static axial compressive load tests of two single piles and a group of four piles with diameter 800 mm and 12 m length were also conducted. The experiment results show that the bearing capacity of every single pile is 1.200 kN with settlement 6.93 mm and the group of four CSpiles is 3.200 kN with settlement 5.03 mm. The results presented in the paper illustrate that SCpile is the suitable solution for foundation construction process with low cost and saving time for high rise buildings. The result shows a capable application of soil cement piles for support of high-rise buildings.

In-situ High Strain Dynamic Testing (HSDT) was developed more than 40 years ago. When a hammer or drop weight strikes the top of a pile, a compressive stress wave travels down its shaft at a speed that is a function of the elastic modulus and mass density. The impact induces a force and particle velocity at the top of the pile that can be measured using accelerometers and strain gauges. This paper discusses the theory behind using HSDT instruments and the procedures to calculate the capacity of the pile. The role of selecting the proper instrument to record them is also discussed. Finally, a case history involving the use of HSDT as an instrument for the observational method is presented.

Las ventajas competitivas del Sistema G3 frente a la bentonita, también tiene cabida en un mercado de cimentaciones como el indio, con precios muy bajos de la bentonita. En este artículo se comprueba la transcendencia sobre el coste final de la obra, el aumento de producción y la eliminación de los costes asociados a los fallos de calidad, tal como se expone en este artículo. Ambos benefícios son aportados por el Systema G3.

A closed-ended, steel, pipe pile was densely instrumented with a combination of vibrating-wire strain gauges and electrical-resistance strain gauges at Purdue University. The instrumented pile was driven into a multi-layered soil profile in Indiana, U.S.. Static and dynamic pile load tests were carefully performed on the test pile. The results of these tests allowed us to learn how shaft and base resistances were mobilized when the test driven pile was subjected to axial loads. The load-settlement response, load-transfer curves, unit shaft resistance distribution with depth, and base resistance are presented in the paper. The static bearing capacity of the pile was estimated using five modern CPT-based pile design methods; the performance of these methods was assessed through layer-by-layer comparisons with the static load test results.

The paper presents the results of a series of field tests performed to study the causes of friction fatigue experienced by displacement piles. Four instrumented model piles were installed at a dense sand test-bed site. The test series was designed to impose different levels of cyclic loading during pile installation. Static and cyclic load tests were subsequently performed to study the differences in the axial capacities developed for ostensibly monotonic and cyclic installations. The test results indicated that the mobilized horizontal
effective stress regime that controls pile side friction primarily depends on the in situ sand state, as reflected by the cone penetration test
CPT qc resistance. A zone of highly stressed sand that produced a concentration of high shear resistance was mobilized in the vicinity of the pile base. The horizontal effective stress that acted on the pile shaft reduced in response to cyclic loading, with the largest reductions occurring for high-intensity cyclic loading or when the pile had experienced only a few load cycles during installation. Although cyclic loading caused a reduction in the horizontal effective stress that acted on the pile shaft, the elevated stress built up in the vicinity of the pile base during installation remained higher than that remote from the base. The elevated stress in the vicinity of the pile base only dissipated after cyclic tension loading had been applied.

INTRODUCCIÓN En la naturaleza, los metales se encuentran comúnmente en un estado estable en la forma de compuestos como los óxi-dos, sulfuros y carbonatos. Regresar a este estado primordial es la tendencia química de los productos fabricados con me-tales cuando se exponen a la intemperie. El acero, primor-dialmente formado de una mezcla de hierro y carbono, es un material ampliamente usado en las cimentaciones, pues sus ventajas en las aplicaciones de la ingeniería superan con creces la propensión a la desintegración química. CORROSIÓN ELECTROQUÍMICA La corrosión es el proceso electroquímico gradual que lleva al metal refinado a formar dichos compuestos estables ori-ginales. En el proceso de corrosión interviene siempre un circuito eléctrico, que es formado con un ánodo (metal), un cátodo (agente oxidante) y un electrolítico (solución acuosa, en nuestro caso). El balance de energía puede establecerse mediante las relaciones de reducción-oxidación (Redox), que de acuerdo con Pannoni (2009) dependerán en gran me-dida de la disponibilidad del oxígeno libre en el electrolito (agente oxidante). El proceso se inicia, en un primer momento, con el flujo de electrones que desde el hierro (Fe) viajan hacia el cátodo formado por el propio metal en unión iónica con el agua. Este flujo de electrones permite que el oxígeno libre (O2) di-suelto en el medio convierta los iones de hidrógeno (H +) en Los pilotes metálicos han sido utilizados en todo el mundo como elementos de cimentación por más de 100 años, con lo que exceden las estimaciones de durabilidad teórica. La corro-sión en suelos naturales no alterados es controlada primordialmente por los mecanismos de difusión de oxígeno y disponibilidad de agua del medio. Mediciones experimentales de la corrosión reportadas en la bibliografía apuntan a que los pilotes de acero rara vez se ven com-prometidos estructuralmente por este fenómeno. En este artículo se hace un resumen de los mecanismos que dominan el proceso de corrosión, tasas de pérdida de acero reportadas en la bibliografía, y se sugiere un método simplificado de verificación de la capacidad estructural de perfiles H o I considerando dicha corrosión. ARTÍCULO TÉCNICO agua (balance ácido), o el agua en iones de hidróxido (OH-, balance alcalino). En el siguiente paso, el coloide de agua y hierro son combinados con el oxígeno para formar uno de los óxidos de hierro: óxido hidratado de hierro (Fe2O3 (H2O)n), hidróxido de hierro (Fe(OH)3) u óxido-hidróxido de hierro (FeO(OH)). Estos óxidos (cuya colectividad llamamos "herrumbre") es depositada en la superficie del metal madre (véase figura 1) formando una barrera débil que puede ralen-tizar el proceso (si no es retirada por abrasión). Este proceso es también determinado por las caracterís-ticas electroquímica del medio, que aceleran o ralentizan el proceso como consecuencia del balance catiónico. Figura 1. Proceso de oxidación del acero. Electrolito O2 + H2O Ánodo Fe  Fe 2+ + 2e-Cátodo O2 + 4H + + 4e- 2H2O Acero OH-OH-OH-Fe(OH3) e-e-e-Fe 2+ Fe 2+ Fe 2+

Offshore drilling refers to a mechanical process where a wellbore is drilled in the seabed. It is classically carried out in order to explore for and subsequently extract petroleum which lies in rock formations beneath the seabed. Piled foundations are the most common foundations for offshore constructions. Driving the piles into the seabed is the standard method of installation. Different foundation concepts have been presented and applied to offshore ocean rig design and constructed everywhere the world. The selection of the foundation concept for an offshore ocean rig is governed by several factors, which comprise of soil conditions, the water depth at the location, the erosion, the weight of total structure, the foundation cost etc. The paper addresses the key designs of pile tip. Due to impact of pile tip on the sea bed, the tip of pile gets deformed. So optimization of tip was done of different tip designs. The modeling was done using solid works and CATIA, analysed using ANSYS software.

A new RC arch bridge called'Eye' has been constructed in Skopje. Arch bridges transfer significant lateral loads to foundations, so lateral load test on two full-scale RC bored piles has been performed on Site to prove actual load capacity of the pile-soil system. Article describes whole procedure of the lateral load test and selected part of the conducted research with test results.

A new method for calculation of head displacement and rotation of laterally loaded rigid monopiles and poles in multilayered heterogeneous elastic soil is presented. The analysis considers the soil as a layered elastic continuum in which the modulus vary linearly with depth within each layer. Rational pile and soil displacement fields are assumed, and the interaction between the pile and soil is taken into account by using the principle of virtual work. Two sets of equilibrium equations, one describing the pile displacement and rotation and the other describing the displacements in the soil, are obtained and solved analytically and numerically following an iterative algorithm. The new method produces pile responses as accurate as those obtained from three-dimensional finite element analysis but does not require any elaborate input for geometry and mesh.

In various analytical, semi-analytical and numerical studies on laterally loaded piles, the pile is conventionally modelled as an Euler-Bernoulli beam. Modelling large-diameter monopiles and piles using the Euler-Bernoulli beam theory may not be appropriate, because the Euler-Bernoulli beam theory is strictly valid for long, slender piles and does not account for shear deformations, which may have a significant effect on the lateral pile response of large-diameter piles. In order to investigate the effect of shear deformation in the modelling of monopiles and piles, a framework for static analysis of laterally loaded piles is developed, in which the monopile/pile is modelled using the Timoshenko beam theory and the soil as an elastic continuum. A rational soil displacement field is assumed and the differential equations of pile and soil displacements are obtained using calculus of variations. Solutions are obtained analytically and numerically following an iterative scheme. The analysis framework also incorporates the Euler-Bernoulli and rigid beam theories as progressive simplifications of the Timoshenko beam theory. Pile responses obtained using the three beam theories are compared with three-dimensional finite-element analysis to establish the relative accuracies of each beam theory in predicting lateral pile response. Systematic parametric studies are performed to establish which beam theory is most appropriate to model laterally loaded monopiles and piles, particularly the largediameter piles, and to find out the range of applicability of the different beam theories in predicting lateral pile response. The Timoshenko beam theory can be used for all cases of laterally loaded piles to produce the most accurate results, particularly for piles with hollow cross-sections. The Euler-Bernoulli beam theory produces accurate results for most piles with solid cross-sections. The rigid beam theory can be used for a quick initial estimate of pile head displacement, particularly for piles with high values of relative pile-soil stiffness ratio.

This study was carried out to undrestand some specific problems that limit safe design and construction of structures on problematic soils. An experimental study was undertaken to examine the influence of the rate of loading and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural material was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39, 57 and 75 %. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shear rate was found to decrease the shear stress and internal friction angle at all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between the organic soil and structural material. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength. Introductıon Shear strength is a significant property alongside other geotechnical properties in design and construction of structures. Shear strength often plays an essential role when any civil engineering application comes across soils which contain organic matter. Shear resistance is a concern factor at the construction of a standing construction equipment as well as at the end of construction in supporting the structure. Generally, organic soils posess low shear strength, and can be catigorized as 'problematic soils'. Accuracy in calculating the shear strength of these types of soils is limited to some variables, namely; origin of soil, moisture content, organic content, shear rate and degree of humification [1]. In the case of organic soil, the interface friction between the soil and construction material, such as wood, concrete and steel is found to be another important factor. One can argue that the shear strength of organic soils and hence, the angle of internal friction (peak or residual) is governed by several factors including; soil composition, initial stress state of the sample, soil structure, specimen size and rate of loading. The rate of loading, i.e. rate of strain, has been found to be one of the prominent factors influencing the obtained shear strength parameter [2]. Impact of the shear rate on the residual strength of cohesive soils was studied by many researchers [3, 4, 5]. In these studies, three types of residual strengths were observed when a slow shear rate was applied under drained condition followed by a fast shear rate. These residual strengths named by the effect of positive rate, neutral rate and negative rate. In addition, considerable works have been carried out on the performance of cohesionless soils under different shear rates [5, 6, 7]. Cassagrande and Shannon [6] were among the first to obtain the effect of strain rate on the shear resistance of soil. The researchers carried out triaxial tests on sands at confining pressures ranged from 30 to 90 kPa with strain rates up to 115 % per second. Cassagrande and Shannon [6] found that shear resistance of the dry sand has increased by approximately 10 % from static levels when tested at high rates of loading. The generated pore water pressure was dependent on the strain rate in the undrained triaxial tests. Therefore, the pore water pressure in the residual state was more likely dependent on the shear rate. In other words, the dependence of effective Key Engineering Materials

Determination of interface shear strength is crucial in the design of many geotechnical structures. To study the effect of interface roughness, particle geometry (size and shape), and sand gradation on the interface friction angle, direct interface shear tests were performed for 10 sands with varying particle sizes, shapes, and gradations and four steel surfaces with different levels of rusting. When sheared along the same interface, the interface friction angle was greater for sands with smaller particle sizes and more angular or elongated particle shapes. For a given sand, the interface friction angle increases with increasing surface roughness. For sands with uniform particle size, a unique relationship was found between the normalized surface roughness and the ratio of the sand–steel critical-state interface friction angle to the internal critical-state friction angle of the sand. Given the same surface roughness and mean particle size, smaller critical-state interface friction angles were mobilized for graded sands than for sands with uniform particle sizes.

Many structures (including transmission-line towers, bridges, tall buildings and coastal structures) are founded on piles, which are designed to transmit both vertical and horizontal forces, and resulting moments, to the load bearing strata. The design of such foundations for large lateral repeating loads (e.g. caused by wind, wave action, earthquake) and lateral earth pressures is a challenging task. This paper presents an experimental study that investigates the use of concentric rings (CRs) of small diameter (displacement) piles (SDPs) surrounding a monopile installed in dry sand, with the intention of limiting its rotation (lateral displacement) under repeated lateral loading. The test results showed that the rotation of the monopile, investigated for a range of different repeated lateral loading schemes, was reduced by 35‒75% on account of the densification of the sand achieved during installation of the SDPs and also the lateral confinement they provided to the sand located within the CRs. Significant increases to both the cyclic stiffness and load carrying resistance of the monopile under lateral loading are documented with the inclusion of the SDPs. Further experimental as well as numerical studies are necessary to validate this novel technique and to optimise the geometrical size and network pattern of the SDPs and the CRs.

When an excavation was carried out near an existing pile foundation, lateral soil movement would be induced and in turn generate pile responses (passive pile phenomenon). Previous studies on this phenomenon utilized free-field techniques where the pile and soil models were separated. This study observes passive piles by employing three dimensional finite element analyses by modeling piles as beam element embedded into the soil mass. The focus of this study is shallow excavations up to 4 m with cantilever walls as support, and this study examines comprehensively the effects of wall stiffness, depth of wall embedment and pile distance to wall. Results of the study shows that the wall length and stiffness affect the pile behavior significanty. Furthermore, the pile responses decreases as piles are positioned farther from the wall.
Keywords: passive pile, finite element, parametric study, shallow excavation, retaining wall

Foundations on expansive soils are of great interest to geotechnical engineers. Piles foundations are used in expansive soils to resist the induced heave. Many factors can affect the pile heave in expansive soil. These factors include the pile length, diameter, and pile loading. The depth of active zone and depth of wetting can also affect the pile and surrounding soil heave. A numerical model of a single straight shaft pile constructed in an expansive soil is presented herein. The numerical study concerning pile and soil properties is set to clarify their effect on pile heave. The finite element software, ADINA is used to model the pile and surrounding soil domain and to compute the pile heave. The model is exposed to inundation with various depths of wettings, where net pile and free field heave are computed. The results show that pile length significantly affects the pile heave, while pile diameter has no noticeable effect on pile heave neither has the pile loading. Tracking of the pile movement shows that it begins to settle immediately after decreasing the depth of wetting, returning approximately to its initial state due to loading at zero depth of wetting. ÉTUDE NUMÉRIQUE DE PIEUX EN GRAS SATURÉS EXPANSIVE SOLS RÉSUMÉ Fondations sur sols gonflants sont d'un grand intérêt pour les ingénieurs en géotechnique. Fondations de pieux sont utilisées dans les sols gonflants pour résister à la houle induite. De nombreux facteurs peuvent influer sur le soulèvement de pile dans le sol expansif. Ces facteurs incluent la longueur de la pile, le diamètre et chargement du pieu. La profondeur de la zone active et la profondeur de mouillage peut également affecter la pile et entourant le soulèvement du sol. Un modèle numérique d'une seule pile arbre droit construit dans un sol expansif est présenté ici. L'étude numérique concernant poils et les propriétés du sol est de clarifier leur effet sur la pile soulèvement. Le logiciel d'éléments finis, Adina est utilisé pour modéliser la pile et ses environs domaine des sols et calculer le soulèvement de pile. Le modèle est exposé aux inondations avec différentes profondeurs de mouillages, où pile net et sans soulèvement de terrain sont calculés. Les résultats montrent que la longueur de pile affecte de manière significative le soulèvement de pile, tandis que le diamètre de la pile n'a pas d'effet notable sur la pile ni soulèvement est le chargement de la pile. La traçabilité des mouvements de pile montre qu'il a commencé à régler immédiatement après la diminution de la profondeur de mouillage, revenant à peu près à son état initial en raison de chargement, à zéro la profondeur de mouillage.