Effect of Earthquake on a Single Pile Located in Sloping Ground

2016 ◽  
Vol 7 (1) ◽  
pp. 57-72 ◽  
Author(s):  
R. Deendayal ◽  
T. G. Sitharam ◽  
K. Muthukkumaran
Keyword(s):  
Lateral Displacement ◽  
Soft Clay ◽  
Ground Surface ◽  
Bending Moment ◽  
Single Pile ◽  
Earthquake Loading ◽  
Element Analysis ◽  
Sloping Ground ◽  
Sea Bed ◽  
D 20

Piles are often constructed on natural slope such as sea bed slope in off-shore structures. When piles are constructed on sloping ground, the behaviour of piles under earthquake loading is different from the piles on horizontal ground surface. The dynamic response of a pile subjected to external excitation is a complex phenomenon resulting from the interactions between the pile and the surrounding soil. In the present study, a finite element analysis of a single field pile located on sloping ground was carried out. A single pile of length 30m with embedment length to diameter ratios (L/D) 20, 25 and 30 was located on a crest of soft clay of slopes 1V:1H and 1V:5H, and subjected to dynamic earthquake loading (California Earthquake,1990). From the study, the behaviour of acceleration with time, lateral displacement and bending moment behavior along the pile shaft was studied.

Three-dimensional numerical modelling of discrete piles used to stabilize landslides

2011 ◽  
Vol 48 (9) ◽  
pp. 1393-1411 ◽  
Author(s):  
S. Kanagasabai ◽  
J. A. Smethurst ◽  
W. Powrie
Keyword(s):  
Slip Plane ◽  
Numerical Models ◽  
Three Dimensional ◽  
Ground Surface ◽  
Lateral Force ◽  
Plane Interface ◽  
Single Pile ◽  
Sloping Ground ◽  
Stabilizing Piles ◽  
Rigid Pile

Three-dimensional finite difference analyses have been carried out to investigate the behaviour of a single pile used to stabilize a slipping mass of soil by embedment into a stable stratum. Analyses were initially carried out to determine the reduction in the limiting pile–soil lateral force per metre length, pu, close to the unconfined ground surface. The analyses then explore the failure mechanisms for landslide stabilizing piles categorized by Viggiani. The effects of varying the strength of the slip plane interface between the sliding and stable strata, and of a sloping ground surface on the behaviour of the pile are then investigated. The results from numerical models with a rigid pile, a distinct plane of sliding, and a horizontal ground surface, as assumed by Viggiani, agree well with his theoretical mechanisms. Lower values of pu close to the ground surface and adjacent to the sliding plane are found to reduce the maximum shear resistance that piles can provide to the slipping mass when compared with Viggiani’s theoretical solutions. Further analyses show that the strength of the slip plane interface has a considerable influence on pile behaviour, and that the slope of the ground surface is only significant above a certain angle.

scholarly journals Model Test and Numerical Simulation of Single Pile Response under Combined Loading in Slope

2020 ◽  
Vol 10 (17) ◽  
pp. 6140
Author(s):  
Jianwei Zhang ◽  
Xiaoju Wang ◽  
Hao Wang ◽  
Hongyu Qin
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Lateral Displacement ◽  
Slope Angle ◽  
Combined Loading ◽  
Single Pile ◽  
Soil Pressure ◽  
Foundation Design ◽  
Sloping Ground ◽  
Horizontal Thrust

Vertical loads are commonly transferred by piles primarily in the upper structures. However, lateral loads are also significant compared with vertical loads in pile foundation design. Compared with a pile on level ground, there are many particular characteristics in a pile that is on sloping ground. These characteristics depend on the combined loading and the magnitude of the soil lateral displacement. In order to investigate the pile’s bearing characteristics, a model test was conducted and ABAQUS software was adopted to conduct 3D numerical simulation of a single pile with different slope angles under combined loads. The experimental results indicated that (1) the soil pressure along the slope direction was smaller than the other side, resulting in an asymmetry of the slope soil around the pile, and in turn introducing a horizontal thrust to the pile; (2) with the increase of slope angle, the horizontal thrust increased while the single pile’s bearing capacity decreased; (3) the vertical load caused more pile horizontal displacement with the growth of slope angle; and (4) the pile’s moment and the displacement also increased with the growth of the slope angle. The findings in this study can provide a useful reference in the design of piles or anti-slide piles in sloping ground.

Analysis on Deep Excavation in Soft Soil Located on Sloped Bedrock

2012 ◽  
Vol 170-173 ◽  
pp. 13-19
Author(s):  
Shong Loong Chen ◽  
Cheng Tao Ho
Keyword(s):  
Lateral Displacement ◽  
Retaining Wall ◽  
Soft Soil ◽  
Soft Clay ◽  
Observation Data ◽  
Clay Layer ◽  
Deep Excavation ◽  
Element Analysis ◽  
2D Strain ◽  
Significant Difference

Deep excavations in soft-clay layer on sloped bedrock often leads to lateral displacement on retaining structures and uneven settlement due to unbalanced pressure generated from excavation. A construction project for which an excavation was complete in soft clay layer on sloped bedrock in Taipei City was adopted in the study. It is learned from the observation logs of the studied case that a significant difference exists in the lateral displacement of diaphragm wall and settlement between up and down-slope sides of sloped bedrock. Deep excavation is in fact profoundly complicated interaction between excavation strutting and soil. In general practice, the design of excavation is frequently simplified as a 2D strain behavior. However, the actual excavation on sloped bedrock is quite different from 1D or 2D simulation in a symmetric manner. Therefore, 2D finite element analysis program, PLAXIS, is introduced for the analysis on the behaviors of soil clay layer on sloped bedrock in excavation. The result is compared with onsite observation data, including displacement of retaining wall, settlement, axial loads of struts and others. The result of retaining wall displacement analysis is found consistent with the trend derived from onsite observation, which is possible for reference of similar engineering analyses and designs in the future.

scholarly journals A Parametric Study of Effect On Single Pile Integrity Due to An Adjacent Excavation Induced Stress Release in Soft Clay

2018 ◽  
Vol 8 (4) ◽  
pp. 3189-3193 ◽  
Author(s):  
D. A. Mangnejo ◽  
M. A. Soomro ◽  
N. Mangi ◽  
I. A. Halepoto ◽  
I. A. Dahri
Keyword(s):  
Soft Clay ◽  
Bending Moment ◽  
Small Strain ◽  
Single Pile ◽  
Stress Release ◽  
Pile Shaft ◽  
Induced Stress ◽  
Parametric Studies ◽  
Pile Settlement ◽  
Pile Integrity

To gain new insights into single pile responses to adjacent excavations in soft ground, numerical parametric studies are carried out. An advanced hypoplastic (clay) constitutive model which takes account of small-strain stiffness is adopted. The effects of excavation depths (i.e. formation level) relative to pile were investigated by simulating the excavation near the pile shaft (i.e., He/Lp=0.67), next to (He/Lp=1.00) and below the pile toe (He/Lp=1.33). Among the three cases, the excavation in case of He/Lp=1.33 resulted in the largest pile settlement (i.e. 7.6%dp). On the other hand, the largest pile bending moment was induced in case of He/Lp=0.67.

scholarly journals Effect of Eccentricity in Sandy Slope of Laterally Loaded Single Pile

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.

Settlement Analysis of Single Large-Diameter and Super-Long Bored Piles in Cohesive Soils

2012 ◽  
Vol 594-597 ◽  
pp. 320-326 ◽  
Author(s):  
Rui Kun Zhang ◽  
Ming Lei Shi ◽  
Jin Wang
Keyword(s):  
Hybrid Method ◽  
Load Transfer ◽  
Large Diameter ◽  
Soft Clay ◽  
Small Diameter ◽  
Transfer Characteristic ◽  
Single Pile ◽  
Element Analysis ◽  
Bored Piles ◽  
Axially Loaded

The behavior of single axially loaded large-diameter and super-long bored piles have large difference to single small diameter short piles. The article analyzes the load transfer characteristic of single axially loaded large-diameter and super-long bored piles in deep soft clay in the Yangtze River Delta region. And the hybrid method of finite element analysis of rod structure coupling with the shear displacement method for single pile was utilized to simulating and predicting the single pile performance. It is verified that the settlement calculation hybrid method in this paper is reliable.

scholarly journals A Simplified Nonlinear Method for a Laterally Loaded Pile in Sloping Ground

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Pingbao Yin ◽  
Wei He ◽  
Zhaohui Joey Yang
Keyword(s):  
Slope Angle ◽  
Ground Surface ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Nonlinear Method ◽  
Sloping Ground ◽  
Lateral Capacity ◽  
Force Increase ◽  
Parametric Studies ◽  
Lateral Behavior

A simplified nonlinear method was proposed to evaluate lateral behavior of a pile located in or nearby a slope, based on the traditional p-y method. This method was validated with field test results of a steel pipe pile in clay and model tests of piles in sand slopes. The comparison indicated that the calculated horizontal displacement and bending moment of piles agree well with experimental results. Then, parametric studies were performed, and it shows that horizontal displacement, rotation, bending moment, and shear force increase along with increasing slope angles; the depth of maximum moment locates at about 1.6 D below ground surface for horizontal ground, while this value turns to be about 3.6 D and 5.6 D for sloping ground of 30° and 60°, respectively. The study clearly shows that slope angle has a significant effect on the deflection and lateral capacity of piles.

scholarly journals Performance of a Large-Scale Excavation by Bottom-Up Technique in Hangzhou Soft Clay

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ri-qing Xu ◽  
Yi-hong Zhu ◽  
Pan Ding
Keyword(s):  
Large Scale ◽  
Lateral Displacement ◽  
Soft Soil ◽  
Soft Clay ◽  
Ground Surface ◽  
Diaphragm Wall ◽  
Subway Tunnel ◽  
Control Effect ◽  
Foundation Pit ◽  
Rapid Excavation

This paper studied the excavation of a foundation pit above a running subway tunnel in Hangzhou soft soil. The zoned excavation and top-down construction techniques were adopted to control the deformation caused by foundation pit excavation. The excavation was divided into four parts, named Zone A, B, C, and D. Zone A adopted temporary diagonal bracing, and the control effect of deformation was poor; it was cancelled and changed to rapid excavation and thicker cushion in Zones B, C, and D. During the whole construction process, the lateral displacement and settlement of the diaphragm wall, surrounding ground surface, and building settlement were monitored and analysed. The data showed that the lateral displacement of the diaphragm wall was effectively reduced by the zoned excavation technique, and the maximum lateral displacement value of the diaphragm wall in Zone A was the least; rapid excavation and reduced soil exposure time also could effectively control the deformation, and the lateral displacement of the diaphragm wall in Zone C is less than Zone B and Zone D. The ground settlement is strongly related to the lateral displacement of the diaphragm wall. In order to reduce the surrounding ground and building settlements, efforts should be made to reduce the wall lateral displacement.

scholarly journals Effect of Loading Direction and Slope on Laterally Loaded Pile in Sloping Ground

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Chong Jiang ◽  
Jia-Li He ◽  
Lin Liu ◽  
Bo-Wen Sun
Keyword(s):  
Lateral Displacement ◽  
Three Dimensional ◽  
Bending Moment ◽  
Zero Point ◽  
Internal Force ◽  
Sloping Ground ◽  
Loading Direction ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Pile Deflection

A series of three-dimensional finite element analyses were performed to study the behavior of piles in sloping ground under undrained lateral loading conditions. The analyses have been conducted for slopes with different angles and two loading directions. The obtained results show that as the slope increases, it can cause greater lateral displacement and internal force of the pile. In addition, the increase of the slope ratio will cause the position of the maximum bending moment and soil resistance zero point of the pile to move downward, further increasing the pile deflection. Furthermore, when the pile distance from slope crest B < 7D, the displacement and internal force development of the pile under toward loading is more obvious. When the pile distance from the slope crest exceeds 7D, the effect of loading direction on the pile can be neglected.

Effect of Skirts on the Lateral Capacity of Mudmats in Soft Clay

2013 ◽  
Author(s):  
Jianchun Cao ◽  
Luo Yang
Keyword(s):  
Finite Element ◽  
Lateral Displacement ◽  
Soft Clay ◽  
Three Dimensional ◽  
Soil Mass ◽  
Element Analysis ◽  
Lateral Capacity ◽  
Fea Model ◽  
Rate Of Increase ◽  
Three Dimensional Finite Element

This paper presents the development of a three-Dimensional Finite Element Analysis (3D FEA) model using Finite Element Code PLAXIS 3D to investigate the skirt’s effect on the lateral capacity of a mudmat in soft clay. It is found that, for a skirted mudmat, 1) the stiffness of skirts had an influence on the mobilization of its ultimate lateral capacity; 2) the required lateral displacement to mobilize the ultimate lateral capacity was about 1% of its width; 3) the lateral capacity is proportional to skirt depth under a soft clay condition with a linearly increasing strength; 4) the ultimate lateral capacity can also be increased by adding internal skirts, but the rate of increase becomes less prominent with the increase of internal skirt number; 5) an empirical formula in ISO19901-4 [5] was confirmed to conservatively estimate the lateral capacity of a skirted mudmat. Moreover, the influence of skirt on the involved soil mass was discussed.

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