scholarly journals An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Mahdy Khari ◽  
Khairul Anuar Kassim ◽  
Azlan Adnan
Keyword(s):  
Pile Group ◽  
Experimental Investigations ◽  
Pile Groups ◽  
Dense Sand ◽  
Spacing Effects ◽  
Pile Diameter ◽  
Lateral Resistance ◽  
Model Pile ◽  
Pile Interaction ◽  
Subgrade Modulus

Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratiol/d= 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing ofs/dfrom 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio ofs/dmore than6dis large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

scholarly journals Response of Single and Grouped Pile Subjected to Lateral Load in Cohesionless Soil

2015 ◽  
Vol 773-774 ◽  
pp. 1397-1401 ◽  
Author(s):  
Mahdy Khari ◽  
Khairul Anuar Kassim ◽  
Payman Alimohammadi
Keyword(s):  
Lateral Load ◽  
Cohesionless Soil ◽  
Experimental Investigations ◽  
Single Pile ◽  
Pile Groups ◽  
Dense Sand ◽  
Pile Diameter ◽  
Model Pile ◽  
Pile Interaction ◽  
Group Pile

Piles are generally required to transfer load from a superstructure through weak or compressible strata, or through water, on to stiffer and less compressible soils and rock. The pile behavior is very important in Soil-Pile interaction (as known Kinematic Interaction) so that grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. In this research presents a series of experimental investigations carried out on single and group pile subjected to monotonic lateral loadings. The aluminum model piles were tested in the different relative densities in Johor Bahru sand. The sand samples were prepared by using the newly designed Mobile Pluviator adopted the air pluviation method. The different configurations of model pile groups for embedded length-to-diameter ratio equal to 32 into loose and dense sand spacing from 3 to 6 pile diameter (D) were conducted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. A ratio of s/D more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Experimental study of interaction and coupling effects in pile groups subjected to torsion

2008 ◽  
Vol 45 (7) ◽  
pp. 1006-1017 ◽  
Author(s):  
L. G. Kong ◽  
L. M. Zhang
Keyword(s):  
Coupling Effect ◽  
Pile Group ◽  
Test Results ◽  
Pile Groups ◽  
Coupling Effects ◽  
Lateral Resistance ◽  
Torsional Resistance ◽  
Pile Interaction ◽  
Group Configuration ◽  
Centrifuge Model Tests

Piles in a pile group subjected to torsion simultaneously mobilize lateral and torsional resistances. Hence, complicated pile–soil–pile interaction effects and load deformation coupling effects occur in the pile group. In this study, a series of centrifuge model tests were carried out to investigate these effects in three-diameter spaced 1 × 2, 2 × 2, and 3 × 3 pile groups subjected to torsion in both loose and dense sands. The test results showed that the effect of horizontal movement of a pile on lateral behaviors of its adjacent piles is significant in 3 × 3 pile groups and such effect varies with group configuration and pile position. The p-multiplier concept can be used to quantify the effect and values for the p-multiplier are suggested. The effect of lateral movement of a pile on the torsional resistances of its adjacent piles and the effect of torsional movement of a pile on the lateral resistances of its adjacent piles were found to be minor in these tests. For an individual pile in a pile group subjected to torsion, the mobilized lateral resistance was found to substantially increase the torsional resistance of the pile. Such a coupling effect is quantified by a coupling coefficient, β, which describes the contribution of subgrade reaction to the increase of torsional shear resistance.

scholarly journals Model Researchon Oblique Load Carrying Capacity of Batter Pile Groups

2019 ◽  
Vol 8 (6S4) ◽  
pp. 880-883
Keyword(s):  
Pile Group ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Uplift Capacity ◽  
Pile Groups ◽  
Dense Sand ◽  
Load Carrying ◽  
Uplift Load ◽  
Batter Piles ◽  
Oblique Load

Experimental investigations on model vertical and batter pile group in uniform sands are presented. Mild steel piles in two different medium ofsand are used in this investigation. The tests are conducted on model steel pile installed in medium, and dense sand withL/d ratio is 18.75 and different batter angles of 0°, 10°, 20°, and 30°. These piles are constructed in sand and subjected to uplift loads of 60° inclination. It was found that the uplift capacity of vertical and batter piles under inclined pulls increased with increase in inclination of piles.it is also observed it a negative batter pile has greater uplift load than positive batter pile

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 Numerical modelling of perimeter pile groups in clay

2013 ◽  
Vol 50 (3) ◽  
pp. 250-258 ◽  
Author(s):  
A.V. Rose ◽  
R.N. Taylor ◽  
M.H. El Naggar
Keyword(s):  
Load Distribution ◽  
Load Capacity ◽  
Relative Effectiveness ◽  
Pile Group ◽  
Block Type ◽  
Pile Groups ◽  
Total Load ◽  
Group Behaviour ◽  
Pile Interaction ◽  
Spacing Length

The load distribution among piles in a group varies such that the inner piles often carry a smaller share of the total load compared to the outer piles, which is a result of increased soil–pile interaction. The main objective of this paper is to establish the relative effectiveness of pile groups with no inner piles (perimeter group), when compared to the more common grid configuration. The numerical investigation utilized the finite element programme ABAQUS and considered a range of variables that affect pile group behaviour including number of piles, pile spacing, length/diameter ratio, and soil strength. It was demonstrated that a complete grid group is less efficient than a perimeter group, where efficiency is defined as the load capacity of the whole group expressed as a ratio of the number of piles in the group multiplied by the load capacity of a single isolated pile. Efficiencies close to unity were observed for some perimeter groups. Perimeter groups also showed that a “block” type group failure could occur, where piles were placed at a spacing of less than 2.0 pile diameters,d, centre-to-centre. This often, but not always, led to a reduction in the efficiency of the pile group.

Experimental and Numerical Study of Laterally Loaded Pile Groups with Pile Caps at Variable Elevations

2000 ◽  
Vol 1736 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Michael C. McVay ◽  
Limin Zhang ◽  
Sangjoon Han ◽  
Peter Lai
Keyword(s):  
Numerical Study ◽  
Ground Surface ◽  
Pile Group ◽  
Special Device ◽  
Pile Groups ◽  
Finite Element Program ◽  
Lateral Resistance ◽  
Pile Cap ◽  
Element Program ◽  
Pile Caps

A series of lateral load tests were performed on 3×3 and 4×4 pile groups in loose and medium-dense sands in the centrifuge with their caps located at variable heights to the ground surface. Four cases were considered: Case 1, pile caps located above the ground surface; Case 2, bottom of pile cap in contact with the ground surface; Case 3, top of pile cap at the ground surface elevation; and Case 4, top of pile cap buried one cap thickness below ground surface. All tests with the exception of Case 1 of the 4×4 group had their pile tips located at the same elevation. A special device, which was capable of both driving the piles and raining sand on the group in flight, had to be constructed to perform the tests without stopping the centrifuge (spinning at 45 g). The tests revealed that lowering the pile cap elevation increased the lateral resistance of the pile group anywhere from 50 to 250 percent. The experimental results were subsequently modeled with the bridge foundation-superstructure finite element program FLPIER, which did a good job of predicting all the cases for different load levels without the need for soil–pile cap interaction springs (i.e., p-y springs attached to the cap). The analyses suggest that the increase in lateral resistance with lower cap elevations may be due to the lower center of rotation of the pile group. However, it should be noted that this study was for pile caps embedded in loose sand and not dense sands or at significant depths. The experiments also revealed a slight effect for the case of the pile cap embedded in sand with a footprint wider than the pile row. In that case the size of the passive soil wedge in front of the pile group, and consequently the group’s lateral resistance, increased.

Negative skin friction from surface settlement measurements in model group tests

1995 ◽  
Vol 32 (6) ◽  
pp. 1075-1079 ◽  
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.

scholarly journals Comparison of static lateral behavior of three pile group configurations using three-dimensional finite element modeling

2018 ◽  
Vol 55 (1) ◽  
pp. 107-118 ◽  
Author(s):  
Murad Abu-Farsakh ◽  
Ahmad Souri ◽  
George Voyiadjis ◽  
Firouz Rosti
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Three Dimensional ◽  
Pile Group ◽  
Lateral Load ◽  
Material Behavior ◽  
Soil Resistance ◽  
Pile Groups ◽  
Element Modeling ◽  
Lateral Resistance

The lateral resistance of three pile group configurations was investigated using three dimensional (3-D) finite element modeling. The three pile groups considered in the study were a vertical pile group, a battered pile group, and a mix of vertical and battered piles in a group. The study was motivated by the full-scale static load test that was conducted on the M19 pier foundation in the I-10 twin span bridge in Louisiana. The static lateral resistance of the M19 battered pile group was investigated previously using a 3-D finite element simulation and verified with the aid of experimental results. In the present study, the M19 battered pile group model was used as the basis for the vertical and mixed pile groups for developing their 3-D finite element models. The nonlinear material behavior was accounted for using elastoplastic constitutive models such as the concrete damaged plasticity model and the anisotropic modified Cam clay model. The lateral resistance of the pile groups was investigated in terms of load–displacement, axial load, bending moment, pile damage, soil resistance, and p-multipliers. The results show that the battered pile group had the largest lateral resistance, followed by the mixed and vertical pile groups, respectively. The largest lateral load share was carried by the two middle rows in the battered pile group, while it was in the leading row in the vertical and mixed pile groups. The soil resistance profiles show that the vertical pile group mobilized greater soil resistance than the battered and mixed pile groups at the same lateral load. The back-calculated p-multipliers are the highest in the battered pile group case, followed by the mixed and vertical pile groups, respectively.

Influence of Pile Geometry on Responses of End-Bearing Pile Groups Subjected to Vertical Dynamic Loads

2020 ◽  
Vol 20 (04) ◽  
pp. 2050050
Author(s):  
Lubao Luan ◽  
Xin Deng ◽  
Weiting Deng ◽  
Chenglong Wang ◽  
Xuanming Ding
Keyword(s):  
Superposition Principle ◽  
Pile Group ◽  
Dynamic Responses ◽  
Stress Distributions ◽  
Pile Groups ◽  
Pile Head ◽  
Interaction Factor ◽  
Pile Interaction ◽  
Refined Technique ◽  
End Bearing Pile

An analytical solution is presented for evaluating the dynamic responses of pile groups subjected to vertical harmonic loads. The solution allows us to consider the effects of pile geometry on the pile head impedance of the vertically loaded pile groups by the use of a new dynamic interaction factor. To this end, the stress distributions of the soil surrounding the vertically vibrating pile is first determined for calculating the pile–pile interaction factor, instead of the classical interaction factor based on two-pile displacements in past studies. Accordingly, the impedances of the pile group are derived using the proposed pile–pile interaction factor and the superposition principle. Some selected examples are presented to demonstrate the proposed refined technique for evaluating the dynamic characteristics of the pile group.

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