A practical approach for the consideration of single pile and pile group installation effects in clay: Numerical modelling

2015 ◽  
Vol 2 (3,4) ◽  
pp. 119-142
Author(s):  
Brian B. Sheil ◽  
Bryan A. McCabe ◽  
Christopher E. Hunt ◽  
Juan M. Pestana
Keyword(s):  
San Francisco ◽  
Soft Clay ◽  
Pile Group ◽  
Practical Approach ◽  
Soil Parameters ◽  
Single Pile ◽  
Installation Effects ◽  
Additional Group ◽  
2D Data ◽  
Group Piles

Abstract In this paper, a practical approach for the consideration of single pile and pile group installation effects in clay is presented using some novel procedures implemented in the finite element (FE) software package PLAXIS 2D. Data reported at a soft clay site at Islais Creek, San Francisco are used to provide calibration for the constitutive model and to validate initial predictions of single pile installation effects. A short parametric study was then undertaken to examine the influence of a number of pile/soil parameters on the soil stresses generated around a single pile after installation and subsequent consolidation. In addition, a new simplified method is proposed to consider group installation effects over-and-above those associated with an equivalent single pile involving the volumetric expansion of tunnels within a plane-strain framework. Remarkably, results show that the installation of additional group piles has a negligible influence after consolidation.

Prediction of the horizontal load-displacement curves of pile groups based on the results of single pile tests

2000 ◽  
Vol 37 (5) ◽  
pp. 951-962 ◽  
Author(s):  
António GF de Sousa Coutinho
Keyword(s):  
Pile Group ◽  
Full Scale ◽  
Soil Parameters ◽  
Single Pile ◽  
Horizontal Load ◽  
Pile Groups ◽  
Nonlinear Method ◽  
Pile Test ◽  
Elastic Plastic ◽  
Load Displacement

This paper presents the prediction of horizontal load-displacement curves of pile groups based on the results of single pile tests. Although the same basic model is employed, two different approaches are taken: one assumes soil to be linear elastic-plastic, and the other assumes it to be elastic nonlinear. The model is calibrated on the basis of the results of a full-scale single pile test. Special emphasis is placed on model calibrations, since the success of any prediction method depends on a careful characterization of the soil. Some new approaches for determining the soil parameters are presented. Two methods for predicting load-displacement curves, one from each model approach, are then proposed and discussed. Special emphasis is placed on group efficiency in the elastic-plastic method and on the boundary conditions of the single pile and the pile group in the elastic nonlinear method. Using the soil characteristics from the model calibrations, the load-displacement curves for a given pile group are then predicted. These predictions are compared with the results of a full-scale pile group test carried out at the same site as that of the single pile test. Agreement between the predictions and the test results tends to validate the methods proposed.Key words: displacement predictions, pile groups, model calibration, pile tests.

scholarly journals Static loading tests on small-scale pile groups

2021 ◽  
Vol 72 (1) ◽  
pp. 84-94
Author(s):  
Lan Bach Vu Hoang
Keyword(s):  
Soft Clay ◽  
Pile Group ◽  
Scale Model ◽  
Small Scale ◽  
Outer Diameter ◽  
Pile Groups ◽  
Pile Spacing ◽  
Circular Model ◽  
Group Piles ◽  
Pile Length

36 small-scale model tests in soft clay were conducted to research the performances of pile groups under rigid caps. The parameters studied were the effect of pile length, pile spacing, and the number of piles in a group. The group piles consisted of 4, 6, and 9 circular model piles of 16mm in outer diameter (D), while four kinds of the pile spacing between pile centers 3; 4; 5; and 6 times of the diameter and three types of the embedded pile lengths: 20D; 25D; and 30D were used. For comparison, three single piles with the same diameter and length were also tested under the same condition. The experimental results were discussed based on the following 3 points of view: the pile group efficiency, the settlement ratio, load distribution per pile location in the group pile. All discussion suggested that the pile number and pile spacing in a pile group caused a remarkable interactional effect between piles, whereas the settlement ratios are significantly affected by the pile length. Besides, each pile in the group of 6D pile spacing behaved more individually.

Deformability and consolidation characteristics of soft Bangkok clay using screw plate tests

1990 ◽  
Vol 27 (5) ◽  
pp. 531-545 ◽  
Author(s):  
D. T. Bergado ◽  
K. C. Chong ◽  
P. A. M. Daria ◽  
M. C. Alfaro
Keyword(s):  
Graphical Method ◽  
Soft Clay ◽  
Stress Path ◽  
Soil Parameters ◽  
Test Results ◽  
Coefficient Of Consolidation ◽  
Plate Test ◽  
Settlement Time ◽  
Oedometer Tests ◽  
Test Embankment

This study centred on the performance of the screw plate test (SPLT) to determine the deformability and consolidation characteristics of soft Bangkok clay. For comparison, a series of stress-path-controlled triaxial consolidation tests (tri) were carried out on good quality samples of Bangkok clay taken from the same testing sites and imposed with the same loading conditions as the screw plate tests. Undrained and drained moduli and coefficients of consolidation were obtained from the stress-path-controlled triaxial consolidation tests and were compared with the corresponding values of the screw plate test. In addition, the ultimate bearing capacity was derived from the pressure–deformation relationships of the screw plate test results. A graphical method was used to compute the coefficient of consolidation from the screw plate tests and from stress-path-controlled triaxial consolidation test results. The compressibility data were also obtained from conventional oedometer tests (oed). Both cv (SPLT)/cv (tri) and cv (SPLT)/cv(oed) ratios compared favorably with the cv (field)/cv (laboratory) ratio obtained from past investigations. The data from pressure–settlement–time relationships of the screw plate tests were used to successfully predict values that compared favorably with the measured values at each stress level. The pressure–deformation–time relationship from stress-path-controlled triaxial consolidation tests were also evaluated, and they indicated behaviour similar to that of the screw plate test results. Soil parameters obtained from screw plate tests were subsequently used to predict the settlement of two test embankments, giving fairly close agreement with the observed values. Key words: soft clay, settlement, deformation, consolidation, screw plate test, triaxial test, embankment, prediction, stress path.

scholarly journals Design Charts for Axially Loaded Single Pile Action

2019 ◽  
Vol 5 (4) ◽  
pp. 922-939 ◽  
Author(s):  
Anis Abdul Khuder Mohamad Ali ◽  
Jaffar Ahemd Kadim ◽  
Ali Hashim Mohamad
Keyword(s):  
Clay Soil ◽  
Skin Resistance ◽  
Soft Clay ◽  
Single Layer ◽  
Load Test ◽  
Engineering Properties ◽  
Single Pile ◽  
Dense Sand ◽  
Design Charts ◽  
Pile Length

The objective of this article is to generating the design charts deals with the axially ultimate capacity of single pile action by relating the soil and pile engineering properties with the pile capacity components. The soil and are connected together by the interface finite element along pile side an on its remote end.  The analysis was carried out using ABAQUS software to find the nonlinear solution of the problem. Both pile and soil were modeled with three-dimensional brick elements. The software program is verified against field load-test measurements to verify its efficiency accuracy. The concrete bored piles are used with different lengths and pile diameter is taken equals to 0.6 m. The piles were installed into a single layer of sand soil with angles of internal friction (20° t0 40°) and into a single layer of clay soil with Cohesion (24 to 96) kPa.  The getting results showed that for all cases study the total compression resistance is increased as pile length increased for the same property of soil, also illustrious that the total resistance of same pile length and diameter increased as the soil strength increasing. In addition, the same results were obtained for the end bearing resistance, skin resistance and tension capacity. Design charts were constructed between different types of soil resistance ratio and the pile length/diameter ratio (L/D) for all cases of study. One of improvement found from these curves that it is cheaply using piles of larger diameter than increasing their lengths for dense sand and to increasing piles lengths for loose sand. Moreover, it is inexpensively using piles of larger length in soft clay soil than increasing their diameter and piles of larger diameter in firm and stiff clay soils than increasing their length.

Simplified Analytical Solutions for Tunnel Settlement Induced by Axially Loading Single Pile and Pile Group

2021 ◽  
Vol 147 (12) ◽  
Author(s):  
Yixian Wang ◽  
Jian Liu ◽  
Panpan Guo ◽  
Wei Zhang ◽  
Hang Lin ◽  
...  
Keyword(s):  
Analytical Solutions ◽  
Pile Group ◽  
Single Pile

scholarly journals Influence of the phase difference between kinematic and inertial loads on seismic behaviour of pile foundations in layered soils

2020 ◽  
Author(s):  
Thejesh Kumar Garala ◽  
Gopal Madabhushi
Keyword(s):  
Natural Frequency ◽  
Free Field ◽  
Phase Relationship ◽  
Phase Variation ◽  
Bending Moment ◽  
Pile Group ◽  
Pile Foundations ◽  
Single Pile ◽  
Seismic Behaviour ◽  
Soil Layers

A series of dynamic centrifuge experiments was conducted on model pile foundations embedded in a two-layered soil profile consisted of soft-clay layer underlain by dense sand. These experiments were specifically designed to investigate the individual effect of kinematic and inertial loads on a single pile and a 3×1 row pile group during model earthquakes. It was observed that the ratio of free-field soil natural frequency to the natural frequency of structure might not govern the phase relationship between the kinematic and inertial loads for pile foundations as reported in some previous research. The phase relationship obtained in this study agrees well with the conventional phase variation between the force and displacement of a viscously damped simple oscillator subjected to a harmonic force. Further, as expected, the pile accelerations and bending moments can be smaller when the kinematic and inertial loads act against each other compared to the case when they act together on the pile foundations. This study also revealed that the peak kinematic pile bending moment will be at the interface of soil layers for both single pile and pile group. However, in the presence of both kinematic and inertial loads, the peak pile bending moment can occur either at the shallower depths or at the interface of soil layers depending on the pile cap rotational constraint.

Installation Effects of DSM in Soft Clay and its Influence on Adjacent Tunnel

2012 ◽  
Author(s):  
Jin-Jian Chen ◽  
Jun-Feng Zhang ◽  
Jian-Hua Wang ◽  
Yan-Fei Zhu
Keyword(s):  
Soft Clay ◽  
Installation Effects

An experimental investigation into pile group-layered soil interaction

1996 ◽  
Vol 31 (5) ◽  
pp. 371-375
Author(s):  
K Chandrashekhara ◽  
S Joseph Antony ◽  
J Mallikarjuna Reddy
Keyword(s):  
Numerical Solutions ◽  
Interaction Analysis ◽  
Pile Group ◽  
Layered Soil ◽  
Single Pile ◽  
Photoelastic Method ◽  
Soil Medium ◽  
Interaction Factor ◽  
Pile Cap ◽  
Soil Interface

An interaction analysis of an axially loaded single pile and pile group with and without a pile cap in a layered soil medium has been investigated using the two-dimensional photoelastic method. A study of the pile or pile group behaviour has been made, varying the pile cap thickness as well as the embedded length of the pile in the hard stratum. The shear stress distribution along the pile-soil interface, non-dimensionalized settlement values of the single pile and the interaction factor for the pile group have been presented. Wherever possible, the results of the present analysis have been compared with available numerical solutions.

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