Pile Groups In Sand Research Articles

Numerical Analysis of Laterally Loaded 3 × 3 to 7 × 3 Pile Groups in Sands

The coupled bridge foundation-superstructure finite-element code FLPIER was employed to predict the lateral response of the single piles and 3 × 3 to 7 × 3 pile groups founded in both loose and medium dense sands. The p-multiplier factors suggested by McVay et al. for laterally loaded pile groups with multiple pile rows were implemented for the predictions. The soil parameters were obtained through a back-analysis procedure based on single pile test results. The latter, as well as the numerical predictions of both the single and group tests, are presented. It was found that the numerical code FLPIER did an excellent job of predicting the response of both the single piles and the 3 × 3 to 7 × 3 pile groups. The latter involved the predictions of lateral load versus lateral deflection of the group, the shears and bending moments developed in the individual piles, and the distributions of the lateral loads in each pile row, which were all in good agreement with the measured results.

Centrifuge Testing of Vertically Loaded Battered Pile Groups in Sand

Abstract Vertical load tests were carried out on 3 by 3 and 4 by 4 fixed head battered pile groups on a centrifuge. These tests simulated 0.43-m-wide by 13.7-m-long square piles founded in loose (Dr = 36%) and medium dense (Dr = 55%) sands at three-diameter spacing. The axial load and shear in each pile were measured during the tests. Numerical analysis was also carried out to predict the battered pile behavior using a coupled bridge foundation-superstructure finite element code (FLPIER). It was found that the vertical capacity of a battered pile group was slightly larger than that of a corresponding plumb pile group. The shear forces and bending moments in battered piles induced by design vertical loads were approximately one third of the ultimate lateral capacity.

Centrifuge Testing of Large Laterally Loaded Pile Groups in Sands

An apparatus was developed to load large pile groups (3 × 3 to 7 × 3) founded in sand in the centrifuge laterally. The device consists of a hydraulic jack apparatus to install the piles, strain gauge instrumentation, and a data acquisition system. The instrumentation allowed the determination of both bending moments and shear forces at the head of each pile. Lateral load tests of 3 × 3 to 7 × pile groups were conducted in both loose and medium dense sands. Based on the test results, the pile group interaction effects were investigated. It was found that the p-y multiplier concept was valid. Also, the p-y multipliers (p specifically) are found to be independent of soil density and only a function of the pile group geometry. For this study (pile spacing was fixed at 3 diameters), they were found to be only a function of row position. Single pile tests were also completed for comparison purposes.

Centrifuge Testing of Plumb and Battered Pile Groups in Sand

Pile groups are generally used under structures subject to heavy axial loads or large lateral forces with or without scour. The focus in this paper is only on pile groups subject to large lateral forces. Currently, little, if any, full-scale lateral load data exist on pile groups that vary pile head fixity or batter. Reported here is the summary of a series of centrifuge tests on free- and fixed-head plumb and battered pile groups. Influence of pile head constraint, pile spacing, soil density, and vertical dead load is reported for groups ranging from 3 × 3 to 3 × 7 in size. Results reveal a significant lateral resistance of fixed- over free-head pile groups; fixed-head piles develop significant axial forces; battered piles without vertical dead loads are generally no better than plumb piles; and in the case of plumb piles, the use of multipliers to represent group interaction is valid.

Centrifuge Testing of Fixed-Head Laterally Loaded Battered and Plumb Pile Groups in Sand

Abstract Centrifuge tests were conducted on driven in-flight fixed-head plumb and battered 3 × 3 pile groups at three-diameter (3D) and five-diameter (5D) spacings. The piles simulated 430-mm-diameter by 13-m-long pipe piles founded in medium loose (Dr = 33%) and medium dense (Dr = 55%) sands. The battered groups were in an A frame arrangement, i.e., each pile in a given row battered the same. Results of the tests showed that fixed-head plumb groups have a 30 to 55% higher lateral resistance than free-headed piles depending on soil density and pile spacing. For the battered 3D-spaced group, the lateral resistance was greater by 20 to 50% than the fixed-head plumb response in the medium dense sand; however, in the medium loose sand, the battered and plumb fixed-head group response was very similar. The latter is attributed to the limited axial tension capacity of the piles in the medium loose sand (Dr = 33%). Increasing the dead load on a battered group to 45% of its axial capacity resulted in a 30% increase in the group's lateral resistance. The lateral resistance of the 5D-spaced battered groups were in all cases greater than their 3D counterparts.

Centrifuge Modeling of Laterally Loaded Pile Groups in Sands

Abstract Presented is a novel apparatus to drive and laterally load groups of six to nine piles in flight. The main component of the device is a flat plate with multiple apertures which are opened or closed through pneumatic solenoids while being raised or lowered with stepping motors via a PC. Presently, both lateral load versus deformation and load distribution within the rows can be measured. Testing on both loose and medium dense sands at three and five-pile-diameter spacings have been completed for free-headed groups of nine piles. It was found that as the soil's density increased, so did the group's lateral resistance as well as the variation from row to row. The five-pile-diameter groups carried larger lateral loads and resulted in a more even load distribution from row to row than its three-diameter counterpart. Work is underway to test larger groups as well as inclined piles.

Discussion of “ Lateral Load Behavior of Pile Group in Sand ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Discussion of “ <i>Lateral Load Behavior of Pile Group in Sand</i> ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Discussion of “ Lateral Load Behavior of Pile Group in Sand ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Discussion of “ <i>Lateral Load Behavior of Pile Group in Sand</i> ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Discussion of “ Lateral Load Behavior of Pile Group in Sand ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Discussion of “ <i>Lateral Load Behavior of Pile Group in Sand</i> ” by Dan A. Brown, Clark Morrison, and Lymon C. Reese (November, 1988, Vol. 114, No. 11)

Cyclic axial loading analysis of piles in sand : Poulos, H G J Geotech Engng Div ASCEV115, N6, June 1989, P836–852

This paper develops an analysis for the behaviour of a single pile or symmetrical pile group in sand under cyclic axial loading. The analysis allows consideration of the effects of degradation of skin friction, base resistance and soil modulus, the influence of loading rate, and the accumulation of permanent displacements. Laboratory data for skin friction degradation are presented and it is shown that the amount of degradation due to cyclic loading depends on the cyclic displacement, the number of cycles, the soil type, and the type of pile. Theoretical solutions for a hypothetical pile and a recent field test emphasize the importance of determining whether the degradation of skin friction depends on the absolute cyclic displacement or the cyclic displacement relative to the pile diameter (a).

Lateral load behaviour of pile group in sand

Lateral load behaviour of pile group in sand

Cyclic Axial Loading Analysis of Piles in Sand

This paper develops an analysis for the behavior of a single pile or symmetrical pile group in sand under cyclic axial loading. The analysis allows consideration of the effects of degradation of skin friction, base resistance and soil modulus, the influence of loading rate, and the accumulation of permanent displacements. Laboratory data for skin friction degradation are presented and it is shown that the amount of degradation due to cyclic loading depends on the cyclic displacement, the number of cycles, the soil type, and the type of pile. Theoretical solutions for a hypothetical pile and a recent field test emphasize the importance of determining whether the degradation of skin friction depends on the absolute cyclic displacement or the cyclic displacement relative to the pile diameter.

Lateral Load Behavior of Pile Group in Sand

A large‐scale group of steel pipe piles and an isolated single pile were subjected to two‐way cyclic lateral loading. The tests were conducted in a submerged firm to dense sand that was placed and compacted around the piles. All of the piles were extensively instrumented so that the variation in soil resistance within the group could be determined. The response of the piles in the group was also compared with the response of the isolated single pile. The loss of efficiency of the piles in the group was related principally to “shadowing” (i.e., the loss of soil resistance of piles in the trailing rows). Piles in the leading row supported a large proportion of the group load and behaved similarly to the isolated single pile. Two‐way cyclic loading had little effect on the distribution of load to the piles in the group, but tended to densify the sand around both the single pile and the group piles.

Lateral load tests on model pile groups : Selby, A G; Poulos, H G Proc 4th Australia-New Zealand conference on geomechanics, Perth, Western Australia, 14–18 May 1984 V1, P154–158. Publ Barton: Inst of Engineers, 1984

A series of laboratory tests on model single piles and pile groups in sand is described. The main objectives of the tests were to examine the effect in laterally loaded pile groups, whereby the front piles carry a greater proportion of load than the rear piles. The tests clearly showed this shielding effect and indicated that, as the load increased towards failure, the sign of the bending moment in the rear piles could even change. Load cycling was found to influence bending moments in the piles, but to have little effect on pile shears. Comparisons between measured and theoretical group deflections, moments, shears and axial forces, showed some measure of agreement, particularly if the theory incorporated pile-soil-pile interaction. However, none of the existing theories was capable of allowing directly for the shielding effect. Consequently, theoretical predictions of shear and moment distributions within laterally loaded pile groups will remain inaccurate until allowance for the shielding effect is made. (Author/TRRL)

Ultimate Pile Capacity for Eccentric Inclined Load

The ultimate bearing capacity of rigid piles and pile groups in sand has been determined under various combinations of eccentricity and inclination of the load varying from the vertical to horizontal directions. The results of load tests on single model piles and free‐standing groups are compared with theoretical estimates. The influence of eccentricity and inclination of the load on the bearing capacity can be represented by simple interaction relationships between the ultimate loads and moments and between the axial and normal components of the ultimate load. The effect of a pile cap resting on the soil in piled foundations is examined on the basis of previous theory and model test results.

Model investigations of pile groups in sand. Closure of discussions of original paper, J. Soil Mech. Found. Div. ASCE : Tejchman, AF Gdansk Tech. Univ. PL V99, SM2, Feb. 1973. 1F, 1R J. Geotech. Engng. Div. ASCE, V100, N.GT10, Oct. 1974, P1160–1162

Model investigations of pile groups in sand. Closure of discussions of original paper, J. Soil Mech. Found. Div. ASCE : Tejchman, AF Gdansk Tech. Univ. PL V99, SM2, Feb. 1973. 1F, 1R J. Geotech. Engng. Div. ASCE, V100, N.GT10, Oct. 1974, P1160–1162

Closure to “Model Investigations of Pile Groups in Sand”

Closure to “Model Investigations of Pile Groups in Sand”

Discussion of “Model Investigations of Pile Groups in Sand”

Discussion of “Model Investigations of Pile Groups in Sand”

Model Investigations of Pile Groups in Sand

An optimizing sewer design program that incorporates discrete dynamic programming optimization is described. This digital computer program determines the least cost combination of pipe sizes and depths for the specified sewer system and constraint set. A design and cost sensitivity analysis for an interceptor sewer is given to illustrate application of the optimizing design system. Cost sensitivity to the design constraints varies markedly from system to system, but for this interceptor it was found that the cost was very sensitive to minimum velocity, Manning n value, design flowrate, and minimum depth. It is estimated that optimization and sensitivity analyses would typically reduce sewer costs from 10 to 20% or more.

An Experimental Study of the Load Distribution in Pile Groups in Sand by Y. O. Beredugo (vol. III., no. 3: 145–66)

An Experimental Study of the Load Distribution in Pile Groups in Sand by Y. O. Beredugo (vol. III., no. 3: 145–66)