Numerical Study of Laterally Loaded Piles in Soft Clay Overlying Dense Sand

This paper presents the results of three dimensional finite element analysis of laterally loaded pile groups of configuration 1×1, 2×1 and 3×1, embedded in two-layered soil consisting of soft clay at liquid limit overlying dense sand using Plaxis 3D. Effects of variation in pile length (L) and clay layer thickness (h) on lateral capacity and bending moment profile of pile foundations were evaluated by employing different values of pile length to diameter ratio (L/D) and ratio of clay layer thickness to pile length (h/L) in the analysis. Obtained results indicated that the lateral capacity reduces non-linearly with increase in clay layer thickness. Larger decrease was observed in group piles. A non-dimensional parameter Fx ratio was defined to compare lateral capacity in layered soil to that in dense sand, for which a generalized expression was derived in terms of h/L ratio and number of piles in a group. Group effect on lateral resistance and maximum bending moment was observed to become insignificant for clay layer thickness exceeding 40% of pile length. For a fixed value of clay layer thickness, lateral capacity and bending moment in a single pile increased significantly with increase in pile length only up to an optimum embedment depth in sand layer which was found to be equal to three times pile diameter and 0.21 times pile length for pile with L/D 15. Scale effect on lateral capacity has also been studied and discussed. Doi: 10.28991/cej-2021-03091686 Full Text: PDF

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Evaluation of p-y Curves and p-multiplier of Pile Groups Corresponding to Sand Properties Change Based on 3D Numerical Analysis

Korean Society of Hazard Mitigation ◽

10.9798/kosham.2020.20.4.207 ◽

2020 ◽

Vol 20 (4) ◽

pp. 207-217

Author(s):

Yongjin Choi ◽

Jaehun Ahn

Keyword(s):

Numerical Analysis ◽

Soil Properties ◽

Pile Group ◽

Friction Angle ◽

Dominant Factor ◽

Group Effect ◽

Pile Groups ◽

Dense Sand ◽

Laterally Loaded Pile ◽

Laterally Loaded

The p-y curve method and p-multiplier (Pm), which implies a group effect, are widely used to analyze the nonlinear behaviors of laterally loaded pile groups. Factors affecting Pm includes soil properties as well as group pile geometry and configuration. However, research on the change in Pm corresponding to soil properties has not been conducted well. In this study, in order to evaluate the effect of soil properties on the group effect in a laterally-loaded pile group installed in sandy soil, numerical analysis for a single pile and 3×3 pile group installed in loose, medium, and dense sand, was performed using the 3D numerical analysis program, Plaxis 3D. Among the factors considered in this study, the column location of the pile was the most dominant factor for Pm. The effect of the sand property change on Pm was not as significant as that of the column location of the pile. However, as the sand became denser and the friction angle increased, the group effect increased, leading to a decrease in Pm of approximately 0.1. This trend was similar to the result reported in a previous laboratory-scale experimental study.

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Design Charts for Axially Loaded Single Pile Action

Civil Engineering Journal ◽

10.28991/cej-2019-03091300 ◽

2019 ◽

Vol 5 (4) ◽

pp. 922-939 ◽

Cited By ~ 1

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.

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Improving Behavior of Tunnel Lining Constructed in Layered Soil Including Soft Clay Layer Using Stone Columns

Arabian Journal for Science and Engineering ◽

10.1007/s13369-013-0650-x ◽

2013 ◽

Vol 38 (12) ◽

pp. 3289-3300 ◽

Cited By ~ 1

Author(s):

Mostafa Abdou Abdel Naiem Mahmoud

Keyword(s):

Soft Clay ◽

Tunnel Lining ◽

Layered Soil ◽

Stone Columns ◽

Clay Layer

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Negative skin friction from surface settlement measurements in model group tests

Canadian Geotechnical Journal ◽

10.1139/t95-105 ◽

1995 ◽

Vol 32 (6) ◽

pp. 1075-1079 ◽

Cited By ~ 4

Author(s):

Mehmet Ufuk Ergun ◽

Devrim Sönmez

Keyword(s):

Soft Clay ◽

Soil Surface ◽

Pile Group ◽

Friction Model ◽

Model Group ◽

Pile Groups ◽

Negative Skin Friction ◽

Dense Sand ◽

Model Study ◽

Negative Friction

Groups of model wood piles driven to end bearing through dense sand over soft clay were used to determine the relative settlement of the soil surface inside and outside the groups as the soil was compressed by air pressure. Square 30 mm piles at spacings of 2 to 6 times the pile width were used in groups of 3 × 3, 4 × 4, and 5 × 5. The results indicate that pile group effects were negligible at pile spacings at 5 to 6 pile widths. Key words : negative friction, model study, pile groups, sand.

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Effect of consolidation on responses of a single pile subjected to lateral soil movement

Canadian Geotechnical Journal ◽

10.1139/cgj-2014-0157 ◽

2015 ◽

Vol 52 (6) ◽

pp. 769-782 ◽

Cited By ~ 14

Author(s):

L.Z. Wang ◽

K.X. Chen ◽

Y. Hong ◽

C.W.W. Ng

Keyword(s):

Soft Clay ◽

Bending Moment ◽

Coefficient Of Consolidation ◽

Construction Period ◽

Soil Movement ◽

Centrifuge Tests ◽

Short Period ◽

Lateral Soil Movement ◽

Pile Response ◽

Pile Length

Given extensive research carried out to study pile response subjected to lateral soil movement in clay, the effect of consolidation on the pile–soil interaction is rarely considered and systematically investigated. For this reason, four centrifuge tests were conducted to simulate construction of embankment adjacent to existing single piles in soft clay, considering two typical drainage conditions (i.e., drained and undrained conditions) and two typical pile lengths (i.e., relatively long pile and short pile). The centrifuge tests were then back-analyzed by three-dimensional coupled-consolidation finite element analyses. Based on reasonable agreements between the two, numerical parametric studies were conducted to systematically investigate and quantify the influence of construction rate and pile length on pile response. It is revealed that by varying drainage conditions, the piles respond distinctively. When the embankment is completed within a relatively short period (cvt/d2 < 2, where cv, t, and d denote the coefficient of consolidation, construction period, and pile diameter, respectively), the pile located adjacent to it deforms laterally away from the embankment. Induced lateral pile deflection (δ) and bending moment reduce with construction period. On the contrary, embankment constructed within a relatively long period (cvt/d2 > 200) leads the pile to deform laterally towards the embankment, with δ and bending moment increases with construction period. By halving the length of pile embedded in the drained ground, the maximum induced bending moment (BMmax) was slightly reduced (by 23%). On the other hand, shortening the length of the pile in the undrained ground is much more effective in reducing BMmax, i.e., halving pile length resulting in 78% reduction in bending moment. A new calculation chart, which takes various drainage conditions and pile lengths into account, was developed for estimation of BMmax.

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Analysis of Laterally Loaded Pile Groups in Improved Soft Clay

International Journal of Geomechanics ◽

10.1061/(asce)gm.1943-5622.0000795 ◽

2017 ◽

Vol 17 (4) ◽

pp. 04016098 ◽

Cited By ~ 10

Author(s):

Amirata Taghavi ◽

Kanthasamy K. Muraleetharan

Keyword(s):

Soft Clay ◽

Pile Groups ◽

Laterally Loaded Pile ◽

Laterally Loaded

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Static loading tests on small-scale pile groups

Transport and Communication Science Journal ◽

10.47869/tcsj.72.1.10 ◽

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.

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Peak punch-through capacity of spudcan in sand with interbedded clay: numerical and analytical modelling

Canadian Geotechnical Journal ◽

10.1139/cgj-2016-0597 ◽

2017 ◽

Vol 54 (8) ◽

pp. 1071-1088 ◽

Cited By ~ 4

Author(s):

Shah Neyamat Ullah ◽

Yuxia Hu

Keyword(s):

Clay Soil ◽

Soft Clay ◽

Friction Angle ◽

Analytical Models ◽

Fe Model ◽

Clay Layer ◽

Dense Sand ◽

Centrifuge Tests ◽

Improved Performance ◽

Sand Plug

The presence of a thin soft clay layer inside a bed of sand may significantly reduce the bearing capacity of the sand layer, imposing a risk of punch-through failure. In this paper, finite element (FE) simulations are reported using a hardening soil (HS) model for sand. The FE model has been verified against centrifuge tests involving loose and dense sand layers overlying clay soil. The effects of sand stiffness, foundation roughness, sand friction angle, undrained clay strength, clay strength nonhomogeneity, and sand and clay layer geometries on the foundation peak capacities have been studied. Punch-through failure is initiated with an inclined sand plug being sheared and pushed into the underlying soft clay. During punch-through, the clay layer fails due to significant radial squeezing. Existing analytical models do not capture the combined failure mechanism of sand shearing and clay radial squeezing. A new analytical model is developed to estimate the peak punch-through capacity of a spudcan in sand with an interbedded clay layer, showing improved performance over the current industry guidelines.

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Effect of Eccentricity in Sandy Slope of Laterally Loaded Single Pile

Civil and Environmental Engineering ◽

10.2478/cee-2019-0013 ◽

2019 ◽

Vol 15 (2) ◽

pp. 92-100

Author(s):

S.V. Sivapriya ◽

R. Balamurukan ◽

A. Jai Vigneshwar ◽

N. Prathibha Devi ◽

A. Shrinidhi

Keyword(s):

Experimental Study ◽

Bending Moment ◽

Cohesionless Soil ◽

Single Pile ◽

Sloping Ground ◽

Lateral Capacity ◽

Governing Factor ◽

Sandy Slope ◽

Ground Condition ◽

Laterally Loaded

AbstractAn experimental study was proposed to understand the behaviour of single pile in sloping ground with various eccentricity. Cohesionless soil was used for conducting experiments with a horizontal ground and with a slope of 1V:2H. With calculated stiffness factor (T) as 92 mm, the eccentricity was varied as 0T, 0.5T and 1T. The lateral capacity of the pile in horizontal and sloping ground condition decreases with increase in eccentricity; the increase in lateral capacity was linear too. The bending moment increases with increase in load; but the depth of maximum bending moment was 0.15 m for 0T and 0.5T of eccentricity. For 1T of eccentricity, the depth of maximum bending moment varied to 0.07 m from the point of load. An equation was proposed to calculate the maximum bending moment of the pile for any eccentricity for a slope of 1V:2H, which is the governing factor for pile designing.

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