IJERT-Numerical Analysis of Single Pile in Soft Clay (original) (raw)
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International journal of engineering research and technology, 2017
Determination of bearing capacity of piles is a complex geotechnical task. Piles are designed to be able to carry and transfer the loads of the structure to the deeper hard strata located at some depth below the ground surface. The purpose of the present study is to investigate the bearing capacity and behavior of piles in sand for single pile and group of two piles. An experimental research program was conducted to study the distribution of the friction along the pile shaft and the load to be transferred by the tip of the pile in cohesionless soil as well as the group effect of two piles. However, the experimental program consisted of testing single and group of two piles in sand under axial compression load. The spacing between piles was three pile diameters. The program consisted of installing test piles in dense sand placed in a soil chamber, and subjecting them to compressive axial load. In total, two load tests were performed in axial compression. First load test was carried o...
IJSRD - International Journal for Scientific Research and Development, 2018
— Numerous techniques are available for finding the ultimate load carrying capacity of piles which includes the static methods, dynamic methods, in-situ penetration tests and the pile load tests. Of these, the static methods, in-situ penetration tests and the pile load tests gives the most reliable results with the pile load tests being the most prevalent of all three. Although there are a number of methods to analytically find out the load carrying capacity, these are often based partly on soil and rock mechanics and partly on empirical methods based on experiments. In this study, the different methods have been analyzed and worked out on various case studies to make a comparison between the results obtained from the different analytical methods to check for the variation in the obtained values and arrive at the methods which gives the most favourable results for obtaining the ultimate bearing capacity and also understand the best approaches for such analytical procedures.
Numerical analysis of pile installation effects in cohesive soils
2017
In this thesis the empirical equation for radial effective stress calculation after displacement pile installation and following consolidation phase has been proposed. The equation is based on the numerical studies performed with Updated Lagrangian, Arbitrary Lagrangian-Eulerian and Coupled Eulerian-Lagrangian formulations as well as the calibration procedure with database containing world-wide 30 pile static loading tests in cohesive soils. The empirical formula has been validated with 10 pile static load tests performed in Poznań clay and its reliability has been compared with 7 pile design methods. In this thesis, the description of research methodology and brief review of Finite Element Method with emphasis on large deformation formulations have been given. The key soil parameters which influence the radial stresses after pile installation and subsoil consolidation, both modelled numerically, have been identified. Next, the numerical methods have been validated with a high quality instrumented pile installation test in London clay and simulations of CPT and CPT-u soundings in Koszalin and Poznań clays, respectively. As a consequence of numerical tests interpretation, the general form of the empirical relation for radial effective stress has been provided. This relation has been calibrated with high quality, 30 pile static load tests. Next, the reliability of pile bearing capacity prediction with the proposed empirical formula has been checked using the database of all 75 piles and reference piles in Poznań site. Besides the validation of the author's equation for radial effective stress after installation and subsequent consolidation, the numerical calculation for the reference pile in Poznań site has been carried out. Numerical calculations include large deformation analysis where all pile construction steps have been taken into account and simplified finite element model where author's empirical formula have been adopted to predict the load-settlement response of the reference pile. Finally, the limitations of the proposed formula are provided and the further possible research directions due to pile installation effects are pointed out.
Numerical Investigation of the lateral load response of piles in soft clay
The paper presents a numerical study on the undrained lateral response of a single, free-head, reinforced concrete pile in soft clays. Soil conditions simulating normally consolidated clays are examined and the pile-soil interaction under static lateral loading is analyzed. The non-linear p-y curves proposed in literature for soft clays are imported into suitable software in order to predict the distribution of the horizontal displacement and bending moment along the pile. The striking differences among these methods require further investigation via 3D finite element analyses. The determination of the ultimate soil resistance p ult from the results of the finite element analyses aims at providing the estimation of a range of values for the ultimate soil resistance coefficient N p with depth and the comparison of the derived values to the corresponding ones proposed by existing methodologies.
A Model Study on Pile Behavior under Inclined Compressive Loads in Cohesionless Soil
International Journal of Engineering Research and, 2015
Pile foundations are extensively used to support various structures built on loose/ soft soils where shallow foundations would undergo excessive settlements or have low bearing capacity. Piles are slender, having high length to width ratio, and are mainly designed to resist axial loads. However, some structures such as high rise buildings, offshore structures, tall chimneys, earth retaining walls are subjected to horizontal or lateral pressure caused by wind force, wave force, traffic movement, earthquake etc. Thus, piles are used as foundation to transmit vertical and lateral loads to the surrounding soil media. In many cases, they may be subjected to inclined compressive loading conditions also. These loads cause lateral and vertical displacements and rotation of the pile cap. These overall behaviors of the piles are estimated from the available conventional theoretical approaches. There are limited experimental studies available on behavior of vertical piles subjected to inclined compressive loads. This paper is an attempt to study the behavior of single pile in cohesionless soil, subjected to varying inclined load until failure with the angle of applied load varying from 0º to 90º from the vertical axis of the pile, through an experimental model study on model mild steel and concrete piles driven into dry river sand. Axial and lateral load carrying capacities of both piles of various slenderness ratios (10, 15, and 20) are found through the loadsettlement diagrams and are compared. The effects of vertical and lateral components of inclined loads on horizontal and vertical displacement of the pile head are discussed. Also, the effects of pile material on the lateral load capacity of piles are studied.
IJERT-A Model Study on Pile Behavior under Inclined Compressive Loads in Cohesionless Soil
International Journal of Engineering Research and Technology (IJERT), 2016
https://www.ijert.org/a-model-study-on-pile-behavior-under-inclined-compressive-loads-in-cohesionless-soil https://www.ijert.org/research/a-model-study-on-pile-behavior-under-inclined-compressive-loads-in-cohesionless-soil-IJERTV4IS110160.pdf Pile foundations are extensively used to support various structures built on loose/ soft soils where shallow foundations would undergo excessive settlements or have low bearing capacity. Piles are slender, having high length to width ratio, and are mainly designed to resist axial loads. However, some structures such as high rise buildings, offshore structures, tall chimneys, earth retaining walls are subjected to horizontal or lateral pressure caused by wind force, wave force, traffic movement, earthquake etc. Thus, piles are used as foundation to transmit vertical and lateral loads to the surrounding soil media. In many cases, they may be subjected to inclined compressive loading conditions also. These loads cause lateral and vertical displacements and rotation of the pile cap. These overall behaviors of the piles are estimated from the available conventional theoretical approaches. There are limited experimental studies available on behavior of vertical piles subjected to inclined compressive loads. This paper is an attempt to study the behavior of single pile in cohesionless soil, subjected to varying inclined load until failure with the angle of applied load varying from 0º to 90º from the vertical axis of the pile, through an experimental model study on model mild steel and concrete piles driven into dry river sand. Axial and lateral load carrying capacities of both piles of various slenderness ratios (10, 15, and 20) are found through the load-settlement diagrams and are compared. The effects of vertical and lateral components of inclined loads on horizontal and vertical displacement of the pile head are discussed. Also, the effects of pile material on the lateral load capacity of piles are studied.
A 3-D finite element study of the response of pile groups in soft clay
This paper presents predictions of the behaviour of a small pile group using the finite element software package PLAXIS 3D Foundation with the advanced Hardening Soil model. In particular, the suitability of this model to the prediction of the response of a well documented single pile and pile group load test at a soft clay test site in Belfast, Northern Ireland is examined. Although the 'wished-in-place' pile installation in PLAXIS does not take into account the complex effective stress regime set up in the soil during pile installation, predictions of pile group behaviour are shown to compare well to measured data. In addition, the role of soil nonlinearity in pile-to-pile interaction is also investigated in order to examine the applicability of the principle of superposition to nonlinear interaction factors. The study indicates that plastic displacements of a loaded pile do not affect the extent of pile-to-pile interaction and thus the principle of superposition also holds for nonlinear interaction factors.
Studia Geotechnica et Mechanica, 2017
In this paper, the whole process of pile construction and performance during loading is modelled via large deformation finite element methods such as Coupled Eulerian Lagrangian (CEL) and Updated Lagrangian (UL). Numerical study consists of installation process, consolidation phase and following pile static load test (SLT). The Poznań site is chosen as the reference location for the numerical analysis, where series of pile SLTs have been performed in highly overconsolidated clay (OCR ≈ 12). The results of numerical analysis are compared with corresponding field tests and with so-called "wish-in-place" numerical model of pile, where no installation effects are taken into account. The advantages of using large deformation numerical analysis are presented and its application to the pile designing is shown.
Numerical investigation on pile group efficiency embedded in soft clay
World Journal of Engineering, 2020
Purpose This paper aims to investigate the pile group efficiency based on the load-settlement response in soft clay conditions, considering several pile configurations using a variable number of piles and pile spacing. The overall objective of the present paper is to provide further insight into the mechanical response of the pile group and aim at helping the engineers in taking a logical path in an iterative design process for pile group efficiency. Design/methodology/approach To investigate the pile group efficiency, three-dimensional (3D) numerical simulations were performed using the finite-difference code FLAC3D. Findings The obtained numerical results are validated by comparing them to those of similar subgrade structure and in comparable geological conditions provided within the literature. The results indicated that although the bearing capacity of the pile group increases with increasing number of piles, the efficiency of the pile group is very important for a small number ...
An analytical approach for the prediction of single pile and pile group behaviour in clay
Computers and Geotechnics, 2016
In this paper, the 't-z method' is employed to describe the nonlinear behaviour of a single pile and is used to obtain simplified predictions of pile group behaviour by considering the interaction between two-piles in conjunction with the Interaction Factor Method (IFM). The principal inconvenience of the t-z method arises from the determination of the resisting curve's shape; an improvement upon this aspect is the main aim of this study. Partial slip is considered using a new analytical approach which is an adaptation of a model based on bond degradation. Pile installation effects and interface strength reduction are uncoupled and considered explicitly in this study. Lateral profiles of mean effective stress after pile installation and subsequent consolidation which were representative of predictions determined in a previous study using a modified version of the cavity expansion method (CEM) are adopted; these predictions are subsequently used to relate installation effects to changes in soil strength and stiffness. In addition, the 'reinforcing' effects of a second, 'receiver', pile on the free-field soil settlement is considered using a nonlinear iterative approach where the relative pile-soil settlement along the pile shaft is related to the soil spring stiffness. Through comparisons with previously published field test data and numerical simulations, the results indicate that the proposed approach provides a sufficiently accurate representation of pile behaviour while conserving considerable computing requirements.