Seismic Soil-pile Interaction Research Articles

Feasibility of modelling large-scale realistic seismic soil–pile interaction problems without supercomputing resources

Feasibility of modelling large-scale realistic seismic soil–pile interaction problems without supercomputing resources

Prediction of the settlement of a pile and assessment seismic soil-pile interaction - An analytical investigation

The pile requires to construct for enhancing the stability of skyscraper and many infrastructures subjected to the linear and nonlinear lateral loads. In this study, the settlement of the pile and prediction settlement of pile were investigated with considering apply seismic loading to the pile in two different directions independently. To minimizing the analytical process the important peaks of the seismic loadings are selected for evaluation of the soil-pile interaction and it compared to the executing the huge number of the analytical process was made in using whole seismic loading in soil-pile interaction assessment and settlement analysis. In statistical analysis, to estimate the accuracy of the analytical outcome the statistical models were applied, to assess the distribution probability of settlement concerning the probability model applied. The results show the direction of seismic loading is particularly important in settlement prediction of the pile. In the calculation settlement, the suggested analytical method minimizes the analytical process for calculation settlement of the pile. The presented method in this study can apply to many problems of nonlinear dynamics.

Evaluation of liquefaction potential of marine sandy soil with piles considering nonlinear seismic soil–pile interaction; A simple predictive model

An elastoplastic, dynamic, finite-difference method was applied to study the effects of nonlinear seismic soil–pile interaction on the liquefaction potential of marine sand with piles. The developed model was well validated using the centrifuge test. The results showed that acceleration, bending moment, and excess pore water pressure complied well with centrifuge test results. The effect of different affecting parameters on liquefaction potential was investigated using parametric study. Using a sensitivity analysis, the pile embedment parameter was shown to be the most influential parameter. Finally, applying the evolutionary polynomial regression technique, a new model for predicting the liquefaction potential was presented.

Evaluation of p-y springs for nonlinear static and seismic soil-pile interaction analysis under lateral loading

In the current state of practice, static/seismic soil-pile interaction is included in design calculations by a set of one-dimensional (1D) uncoupled springs. The guidelines of American Petroleum Institute (API) are often adopted to develop backbone curves for the lateral springs. The purpose of the paper is to assess the reliability of this practice. Twenty-seven static field and laboratory tests, and two dynamic centrifuge tests are simulated to evaluate the performance of the springs. More detailed elaboration on the performance of the springs is provided by simulation of one of the static tests and both of the dynamic tests using also three-dimensional (3D) continuum approach. The evaluation results indicate that API springs do not capture the major mechanisms involved in soil-pile interaction, and this results in erroneous estimation of pile deflections and bending moments. It is shown that the observed errors stem not only from the insufficient characterization of the spring properties (API backbone curves), but also from the inadequate simulation method in which three-dimensional continuum configuration of the supporting soil is represented by a 1D uncoupled spring.

Seismic Soil-Pile Interaction Considering Nonlinear Soil Column Behavior in Saturated and Dry Soil Conditions

Seismic Soil-Pile Interaction Considering Nonlinear Soil Column Behavior in Saturated and Dry Soil Conditions

Centrifuge Modeling of the Seismic Performance of Pile-Reinforced Slopes

An extensive program of centrifuge testing was conducted to quantify the improvements to seismic slope performance that can be achieved by installing a row of discretely spaced vertical precast RC piles. A key novelty of the work presented is the use of recently developed microreinforced concrete to produce realistically damageable model piles. Pile-reinforced slopes are a good example of a problem in which relative soil-pile strength is important in determining whether the soil or pile yields first, and in which the performance of a slope with structurally damaged piles may be of interest. The new model RC allows these factors to be properly accounted for in a reduced-scale physical model for the first time. Two different reinforcement layouts were considered, representing (1) a section specifically detailed to carry the bending moments induced by the slipping soil mass, and (2) a nominally reinforced section with low moment capacity. These were supported by further tests on conventional elastic piles that were instrumented to measure seismic soil-pile interaction. It was demonstrated that dynamic ground motions at the crest can be significantly reduced in amplitude by up to 20% with elastic piles spaced at s/B=3.5, both in terms of the peak acceleration and across the full response spectrum. Permanent deformations at the slope crest (e.g., settlement) were also reduced by up to 35% at s/B=3.5. These findings are consistent with previous suggestions made for the optimal s/B ratio for encouraging soil arching between piles at maximum spacing both under monotonic conditions and from numerical investigations of the seismic problem. The improvements to slope performance were reduced slightly using the designed microreinforced concrete piles owing to deterioration in the bending properties arising from fatigue under the cyclic kinematic loading. This suggests that idealization of RC piles as elastic elements will likely be only an approximation of their true behavior. The importance of reinforcement detailing was also highlighted, with the nominally reinforced section yielding early in the earthquake, and the damaged piles subsequently only offering a small (although measureable) reduction in seismic slope performance compared with the unreinforced case. In addition to these findings, the data presented will be useful in validating future improved numerical models for predicting the performance of piled slopes and for the aseismic design of pile-reinforcing schemes.

Centrifuge shaking table tests on a single pile embedded in clay subjected to earthquake excitation

Pile foundations are extensively used to achieve the bearing capacity required to support heavy superstructure loading, especially under adverse soil conditions. In view of this, the behavior of pile foundations under earthquake loading is an important factor affecting the integrity of infrastructures. In this paper, the results from a series of dynamic centrifuge model tests carried out at the National University of Singapore are presented. The centrifuge experiments were performed to examine response of a single pile in soft clays subjected to earthquake, with special focus on the effect of superstructure loading on the seismic soil–pile interaction. The experimental observations were then compared with the results obtained from a simple theoretical analysis, based on lumped mass approach. The centrifuge test results suggest that the pile does not move in tandem with the ground. The results also indicate that the degree of soil–pile interaction depends on the presence of the superstructural load on the top of the pile.

Experimental p-y loops for estimating seismic soil-pile interaction

Seismic soil-pile interaction is evaluated in this study based on back-calculated p-y loops constructed from sampled data of pile bending moments. Fundamental properties of p-y loops are implemented to derive distributed springs and dashpots, thereby quantifying soil-pile interaction in the realm of a Beam on Dynamic Winkler Foundation modeling. The procedure is validated by means of well-documented centrifuge tests of a single pile supported structure founded on a two-layer soil profile that comprises of soft clay overlying dense sand. Two shaking levels of a real earthquake motion applied at the base of the soil profile were examined and the generated seismic p-y loops were compared to cyclic p-y curves commonly used in pile design practice. The results demonstrate the strong influence of intensity of the input motion on seismic p-y loops while cyclic p-y curves established for soft clays tend to overestimate soil stiffness under strong excitation. Typical sets of recorded and computed structural response are presented, denoting the ability of the BDWF model related to p-y loops in reproducing adequately fundamental aspects of seismic soil-pile interaction.

Seismic soil–pile interaction in liquefiable soil

Numerical analysis of seismic soil–pile interaction was considered in order to investigate the influence of flow mechanisms. Two models were employed—a simplified model, where the pore pressure at any depth is that of the free field, and a more complete model in which the pore pressure is associated with three-dimensional flow. The soil behavior was modeled by a nonlinear, quasi-hysteretic constitutive relation. A parametric study was carried out, varying the superstructure mass and soil permeability. It was found that there is a pore pressure threshold below which both models yield similar results, but that this threshold cannot be quantified a priori, as it depends strongly on soil–pile interaction.