An experimental investigation into pile group-layered soil interaction

1996 ◽  
Vol 31 (5) ◽  
pp. 371-375
Author(s):  
K Chandrashekhara ◽  
S Joseph Antony ◽  
J Mallikarjuna Reddy
Keyword(s):  
Numerical Solutions ◽  
Interaction Analysis ◽  
Pile Group ◽  
Layered Soil ◽  
Single Pile ◽  
Photoelastic Method ◽  
Soil Medium ◽  
Interaction Factor ◽  
Pile Cap ◽  
Soil Interface

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.

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

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.

Soil–pile–cap static interaction analysis by finite and infinite elements

1991 ◽  
Vol 28 (6) ◽  
pp. 771-783 ◽  
Author(s):  
Weiming Liu ◽  
Milos Novak
Keyword(s):  
Interaction Analysis ◽  
Near Field ◽  
Direct Analysis ◽  
Field Soil ◽  
Weak Zone ◽  
Soil Medium ◽  
Infinite Elements ◽  
Static Interaction ◽  
Pile Cap ◽  
Single Piles

A direct analysis of pile–soil static interaction by the combination of finite and infinite elements is presented. The pile and the near-field soil medium are modelled by finite elements, whereas the far-field soil medium is modelled by mapped infinite elements. Axially loaded single piles and single piles with caps subject to monotonic loading are investigated. The soil is assumed to be either elastic or elastic–perfect plastic. A weak zone is introduced around the pile to approximately account for slip between the soil and the pile. Numerical results show that this approach is quite efficient and versatile for various soil–structure interaction problems. Key words: pile, soil, cap, elastoplasticity, finite element, infinite element.

State-of-the-Art Techniques for Seismic Soil-Structure Interaction Analysis of Steel Gravity Structures

2014 ◽  
Author(s):  
Frederick Tajirian ◽  
Mansour Tabatabaie ◽  
Basilio Sumodobila ◽  
Stephen Paulson ◽  
Bill Davies
Keyword(s):  
Soil Structure ◽  
State Of The Art ◽  
Interaction Analysis ◽  
Layered Soil ◽  
Soil Structure Interaction ◽  
Soil System ◽  
Cyclonic Storm ◽  
Structure Interaction ◽  
Analysis Methods ◽  
Moderate Seismicity

The design of steel jacket fixed offshore structures in zones of moderate seismicity is typically governed by Metocean loads. In contrast the steel gravity structure (SGS) presented in this paper, is a heavy and stiff structure. The large mass results in foundation forces from seismic events that may exceed those created by extreme cyclonic storm events. When computing the earthquake response of such structures it is essential to account for soil-structure interaction (SSI) effects. Seismic SSI analysis of the SGS platform was performed using state-of-the-art SSI software, which analyzed a detailed three-dimensional model of the SGS supported on layered soil system. The results of this analysis were then compared with those using industry standard impedance methods whereby the layered soil is replaced by equivalent foundation springs (K) and damping (C). Differences in calculated results resulting from the different ways by which K and C are implemented in different software are presented. The base shear, overturning moment, critical member forces and maximum accelerations were compared for each of the analysis methods. SSI resulted in significant reduction in seismic demands. While it was possible to get reasonable alignment using the different standard industry analysis methods, this was only possible after calibrating the KC foundation model with software that rigorously implements SSI effects. Lessons learned and recommendations for the various methods of analysis are summarized in the paper.

Development of Graphical Method of Pile Group Foundation Design

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.

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

2000 ◽  
Vol 1736 (1) ◽  
pp. 24-32 ◽  
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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