scholarly journals PILE SETTLEMENT INDUCED FROM SOIL MOVEMENT DUE TO BREAKDOWN OF RETAINING WALL

2020 ◽  
Vol 60 (4) ◽  
pp. 338-348
Author(s):  
Rajesh Prasad Shukla
Keyword(s):  
Experimental Model ◽  
Retaining Wall ◽  
Pile Group ◽  
Small Scale ◽  
Embedment Depth ◽  
Pile Groups ◽  
Soil Movement ◽  
Pile Settlement

Very few studies measured the settlement of retaining wall supported piles foundation under a soil movement. This study explores the pile settlement induced from the sudden breakdown of a closely located retaining wall using a small-scale experimental model. Various factors affect the pile settlement, but the influence of the embedment ratio of the pile and collapsed height of the retaining wall is relatively more visible. The induced settlement decreases with pile embedment depth and increases with the collapsed height of the retaining wall. The pile settlement initially increases at a higher rate with an increase in the collapsed height to a certain extent, beyond which, becomes relatively less observable. Pile group settlement reduces with the increase in spacing and the number of piles in longer piles. However, opposite trends have been observed in piles with a smaller embedment ratio. The settlement reduces logarithmically with the increase in the distance between piles and the retaining wall. Pile groups with small embedment ratio are severely more affected by the breakdown of the retaining wall than the piles of a large embedment ratio. Pile groups placed parallel to the retaining wall are more affected than those placed orthogonally.

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.

Small scale model test on lateral behaviors of pile group in loose silica sand

2021 ◽  
Vol 18 (1) ◽  
pp. 41-54
Author(s):  
Amir Vakili ◽  
Seyed Mohammad Ali Zomorodian ◽  
Arash Totonchi
Keyword(s):  
Model Test ◽  
Pile Group ◽  
Lateral Load ◽  
Reduction Factor ◽  
Silica Sand ◽  
Scale Model ◽  
Small Scale ◽  
Pile Groups ◽  
Pile Spacing ◽  
Group Reduction

The accurate predictions of load- deflection response of the pile group are necessary for a safe and economical design. The behavior of piles under the lateral load embedded in soil, is typically analyzed using the Winkler nonlinear springs method. In this method, the soil-pile interaction is modeled by nonlinear p-y curves in a way that the single pile p-y curve is modified using a p-multiplier (Pm) for each row of piles in the group. The average Pm is called the group reduction factor. The Pm factor depends upon the configuration of pile group and the pile spacing (S). The present study was conducted to investigate the effects of various parameters, such as the pile spacing in the group, different layouts and the lateral load angle (Ѳ) change as a new parameter on the Pm factor and group efficiency based on the 1-g model test. The Pm factor is well comparable with the results of the full-scale test on pile group. However, based on the results, the calculated values of the Pm factor for 3×3 pile groups under 2.5-diameter spacing was estimated about 0.38 and under 3.5-diameter spacing was estimated about 0.52, so the calculated values at S/D=3, obtained from interpolation the values of group reduction factor at S/D=2.5 and S/D=3.5, are close to the AASHTO recommendation.

Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

2021 ◽  
Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding
Keyword(s):  
Seismic Behavior ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Pile Group ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Shaking Table Tests ◽  
Pile Groups ◽  
Acceleration Response ◽  
Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

scholarly journals The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading

2019 ◽  
Vol 5 (11) ◽  
pp. 2377-2391
Author(s):  
Aseel Kahlan Mahmood ◽  
Jasim M Abbas
Keyword(s):  
Cyclic Loading ◽  
Cyclic Load ◽  
Lateral Displacement ◽  
Load Ratio ◽  
Pile Group ◽  
Pile Groups ◽  
Group Response ◽  
Load Intensity ◽  
Number Of Cycles ◽  
Aluminum Pipe

This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.

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

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 <i>p-y</i> curve method and </i>p</i>-multiplier (<i>P<sub>m</sub></i>), which implies a group effect, are widely used to analyze the nonlinear behaviors of laterally loaded pile groups. Factors affecting <i>P<sub>m</sub></i> includes soil properties as well as group pile geometry and configuration. However, research on the change in <i>P<sub>m</sub></i> 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 <i>P<sub>m</sub></i>. The effect of the sand property change on <i>P<sub>m</sub></i> 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 <i>P<sub>m</sub></i> of approximately 0.1. This trend was similar to the result reported in a previous laboratory-scale experimental study.

scholarly journals Working Mechanism of Pile Group with Different Pile Spacing in Dense Sand

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Yadong Chen ◽  
Fan Lu ◽  
Abdoullah Namdar ◽  
Jiangdong Cai
Keyword(s):  
Three Dimensional ◽  
Interaction Mechanism ◽  
Pile Group ◽  
Resistance Pattern ◽  
Pile Groups ◽  
Pile Spacing ◽  
Dense Sand ◽  
Energy Mechanism ◽  
Tip Resistance ◽  
Displacement Zone

Complex interaction mechanism exists between the pile group and soil. To realize the pile-soil load transmission mechanism in detail, the failure pattern of pile groups installed in dense sand considering different pile spacing was investigated by means of laboratory experimental model test and three-dimensional discrete element method. The results suggested that the narrow pile spacing was beneficial to the development of the pile tip resistance, and it enhanced the bearing performance of the pile group at the initial stage of settlement. The pile spacing changed the shaft resistance pattern with modification of the strain energy mechanism released within the subsoil. The pile group with 6b pile spacing had higher composite group efficiency. A joint fan-shaped displacement zone was formed beneath the pile tip for the pile group with 3b pile spacing; this pile foundation presented the block failure mechanism. The sand displacement beneath the cap for the pile group with 6b pile spacing mainly located on the upper part of the piles, the sand displacement around both sides of the piles presented asymmetric, and a relatively independent fan-shaped displacement zone was formed beneath the pile tip.

scholarly journals Laboratory development of a vertically oriented penetrometer for shallow seabed characterization

2016 ◽  
Vol 53 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Fauzan Sahdi ◽  
David J. White ◽  
Christophe Gaudin ◽  
Mark F. Randolph ◽  
Noel Boylan
Keyword(s):  
Soil Surface ◽  
Site Investigation ◽  
Soil Strength ◽  
Small Scale ◽  
Soil Parameters ◽  
Embedment Depth ◽  
Fine Grained ◽  
Centrifuge Models ◽  
Measured Resistance ◽  
And Performance

Current site investigation practice for offshore pipeline design relies on soil parameters gathered from boreholes or in situ test soundings to depths of 1–2 m below the mudline. At these depths, the fine-grained seabed is very soft and possesses low undrained strength, which can be difficult to measure. This paper describes a centrifuge test programme undertaken to evaluate the feasibility and performance of a novel penetrometer designed to assess the shallow strength of soft seabed over continuous horizontal profiles. This device is termed the vertically oriented penetrometer (VOP). Tests were performed on a normally consolidated kaolin sample, with the VOP translated horizontally at velocities ranging from 1 to 30 mm/s, after embedding the VOP at 30 and 45 mm depths. All tests involved many cycles of VOP forward and backward movement to assess its potential to derive the ratio of intact to fully remoulded strength. Strength determination is achieved by dragging the VOP at a specified embedment depth along the soil surface, and deriving the soil strength from the measured resistance as if the VOP were a laterally loaded pile. The VOP is shown to yield comparable strength measurements to that of a T-bar penetrometer. The VOP is a potentially valuable addition to the range of tools used to characterize soil strength, both in small-scale centrifuge models and, following practical development, potentially also in the field.

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