Effects of Pile Cap in Single Pile and Lateral Capacity of Pile Group

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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Study on Group Piles Effects of Offshore Engineering under Lateral Load

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.919-921.824 ◽

2014 ◽

Vol 919-921 ◽

pp. 824-827

Author(s):

Sheng Jie Di ◽

Ming Yuan Wang ◽

Wen Bo Du

Keyword(s):

Lateral Load ◽

Soil Reaction ◽

Single Pile ◽

Soil Pressure ◽

Lateral Capacity ◽

Offshore Engineering ◽

Complex Process ◽

Pile Cap ◽

Practical Engineering ◽

Group Piles

The mechanical behavior of group piles under lateral load is a very complex process of pile-soil interaction. Due to the group effect, the lateral capacity of individual piles can not be fully developed. Deduction factors are applied to the lateral soil reaction, and then lateral analysis is performed for individual piles. After p-y curve for each pile is constructed, the soil pressure of group piles is the sum of soil pressure of single pile at the same deflection under one pile cap. The mechanical different behaviors of the front piles and the back piles are analyzed and compared based on a practical engineering.

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Investigation of the end bearing load in pile group model in dry soil under horizontal excitation

Acta geotechnica slovenica ◽

10.18690/actageotechslov.18.1.79-106.2021 ◽

2021 ◽

Vol 18 (1) ◽

pp. 79-106

Author(s):

Mohammed Y. Fattah ◽

Hussein H. Karim ◽

Makki K. M. Al-Recaby

Keyword(s):

Relative Density ◽

Pile Group ◽

Group Model ◽

Single Pile ◽

Maximum Acceleration ◽

Pile Spacing ◽

Bearing Load ◽

Pile Cap ◽

Dry Soil ◽

Load Peak

A series of 94 laboratory tests were conducted to measure the response of pile foundation when subjected to dynamic loads. Eight tests were conducted on single pile in dry soil at relative density 30 % (loose) and 50 % (medium); 66 tests on group of piles with different spacings and patterns. All tests were carried out under operating frequencies 0.5, 1 and 2 Hz under horizontal shaking. All tests were achieved with one embedment ratio (L/d = 30). These tests were grouped in three different numbers of piles; 2 piles in row and line patterns, 3 piles and 4 piles; and three pile spacing ratios (s/d = 3, 4 and 5). The results of dry soil indicating the mechanism of dynamic response of piles and soil subjected to dynamic horizontal shaking include the variation and distribution of acceleration with time in different states of soil in addition to the vertical and horizontal displacements, end-bearing load, peak acceleration and the peak velocity of foundation. It was concluded that for a dry soil bed, the acceleration amplitudes increase with frequency for both soil relative densities (loose and medium) and different pile patterns (number; single or group and different spacing ratios s/d). The maximum acceleration in the foundation is lower than in the soil bed for all operating shaking frequencies, pile spacing ratios and soil states. The decreasing of the maximum acceleration recorded in the foundation as compared to that in the soil bed is between 10-100 % for loose and medium state of soil, and the decrease in loose state is more than in medium state. This means that there is damping effect or attenuation of vibration waves. The amplitudes of recorded acceleration in the pile cap are much higher than in the soil bed for single pile and pile group with different pile spacing ratios, also these amplitudes are increasing with increase of shaking frequency and relative density of the soil.

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Development of Graphical Method of Pile Group Foundation Design

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.845.94 ◽

2016 ◽

Vol 845 ◽

pp. 94-99

Author(s):

Noegroho Djarwanti ◽

Raden Harya Dananjaya ◽

Fauziah Prasetyaningrum

Keyword(s):

Los Angeles ◽

Construction Projects ◽

Graphical Method ◽

Pile Group ◽

Foundation Design ◽

Fast Estimation ◽

Pile Cap ◽

Single Piles ◽

Simplified Analysis

In the construction projects, a pile group foundation is often utilized. The group of bored piles is usually installed relatively close to each other and joined at the top by a pile cap to hold up the loads. In other hand, a fast estimation of the groups of piles capacities are needed in the preliminary design and in other conditions of projects, such as a supervisor of projects want to estimate the capacities of the group of piles. The purpose of this research is to study the correlations of groups of piles efficiencies with the number of piles and to compare the groups of piles capacities with the single piles capacities. Furthermore, this study is aimed to make a fast estimation of groups of piles capacities using proposed graphical method.The piles efficiencies are calculated using several methods, such as Simplified Analysis, Converse-Labare [1][2], Los Angeles Group, Seiler - Keeney, Das, and Sayed - Baker. In order to calculate the groups of piles capacities, the capacities of single piles are needed. The singles piles capacities are taken from graphical method proposed by Djarwanti et al. (2015a and 2015b). Three graphical methods utilized are derived from the Briaud et al. (1985) , Reese and Wright (1977), and Reese O’Neill method. Moreover, the proposed graphical method is applied in the case study. The case study takes palace in Graha Indoland Condotel Inside Yogyakarta Construction Project.The pile efficiency graph is recommended for this research since the value of pile efficiency could be easily taken. The value of pile efficiency for Graha Indoland Condotel Inside using Simplified Analysis, Converse - Labare, Los Angeles Group, Seiler – Keeney, Das, and Sayed – Baker are 1,75; 0,89; 0,94; 0,99; 4,00; 1,56 respectively. Meanwhile the value of pile group capacity with the value of pile group efficiency more than 1, showed that the pile group capacity based on the efficiency is bigger than the one based on single down pattern.

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Lateral Load Capacity and Passive Resistance of Full-Scale Pile Group and Cap

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1736-04 ◽

2000 ◽

Vol 1736 (1) ◽

pp. 24-32 ◽

Cited By ~ 5

Author(s):

Kyle M. Rollins ◽

Andrew E. Sparks ◽

Kris T. Peterson

Keyword(s):

Load Capacity ◽

Pile Group ◽

Lateral Load ◽

Full Scale ◽

Dynamic Resistance ◽

Back Side ◽

Passive Resistance ◽

Passive Pressure ◽

Pile Cap ◽

Measured Resistance

Static and dynamic (statnamic) lateral load tests were performed on a full-scale 3 × 3 pile group driven in saturated low-plasticity silts and clays. The 324-mm outside diameter steel pipe piles were attached to a reinforced concrete pile cap (2.74 m square in plan and 1.21 m high), which created an essentially fixed-head end constraint. A gravel backfill was compacted in place on the back side of the cap. Lateral resistance was therefore provided by pile-soil-pile interaction as well as by base friction and passive pressure on the cap. In this case, passive resistance contributed about 40 percent of the measured static capacity. The measured resistance was compared with that computed by several techniques. The log-spiral method provided the best agreement with measured resistance. Estimates of passive pressure computed using the Rankine or GROUP p-y curve methods significantly underestimated the resistance, whereas the Coulomb method overestimated resistance. The wall movement required to fully mobilize passive resistance in the dense gravel backfill was approximately 0.06 times the wall height, which is in good agreement with design recommendations. The p-multipliers developed for the free-head pile group provided reasonable estimates of the pile-soil-pile resistance for the fixed-head pile group. Default p-multipliers in the program GROUP led to a 35 percent overestimate of pile capacity. Overall dynamic resistance was typically 100 to 125 percent higher than static; however, dynamic passive pressure resistance was over 200 percent higher than static.

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

Journal of Engineering Mechanics ◽

10.1061/(asce)em.1943-7889.0002035 ◽

2021 ◽

Vol 147 (12) ◽

Author(s):

Yixian Wang ◽

Jian Liu ◽

Panpan Guo ◽

Wei Zhang ◽

Hang Lin ◽

...

Keyword(s):

Analytical Solutions ◽

Pile Group ◽

Single Pile

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Design Method for the Base Beam Connected to Single Pile Cap

Advanced Materials Research ◽

10.4028/scientific5/amr.446-449.1520 ◽

2012 ◽

Vol 446-449 ◽

pp. 1520-1523

Author(s):

Cui Hong Ding

Keyword(s):

Design Method ◽

Single Pile ◽

Pile Cap

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

Canadian Geotechnical Journal ◽

10.1139/cgj-2019-0547 ◽

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.

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