Research on Bearing Theory of Squeezed Branch Pile

Based on the shear displacement method, theoretical research on the load transfer relation of squeezed branch pile is established. In combination with the nonlinear relation of the interaction between piles and soil, the hyperbolic function is used to describe the pile tip, pile skin, and branch. The theoretical method of the load transfer is improved, and the expression of the load transfer coefficient of these three parts is given. Finally, the applicability of the theoretical method is verified by the model test of homogeneous soil and the field test of stratified soil. The verification results show that the theoretical calculation method of the squeezed branch single-pile bearing capacity based on the shear displacement method can better calculate the ultimate load in practical engineering applications.

New Method for Calculating the Settlement of Single Pile and Pile Group in Soft Soil Area

This paper fits the τ-z curve of a single pile by mathematical methods. Based on the one-dimensional similarity of the τ-z curves, the τ-z curves of single pile under different loads are derived. It studies the distribution of the axial force of a single pile by taking the self-weight of the pile and the pile-end resistance ratio into account and establishes the calculated equation of settlement for single pile. The mutual reinforcing effect between the piles is fully considered, and the settlement of each foundation pile in the pile group is deduced in use of shear displacement method. The example analysis shows that the axial force distribution of single pile considering the self-weight and the pile-end resistance ratio is in good agreement with the experimental data. The settlement error of a single pile calculated by the traditional method is 18.52% compared with measured value. When the self-weight and end resistance ratio are not considered, the error reaches 2.26%. However, the error could reduce to 1.64% when they are taken into consideration. It has a good applicability to calculate the settlement of pile group through the τ-z curves of single pile. Also, it can better forecast the settlement behavior of the pile group under similar conditions.

Three-Dimensional Ground Settlement Induced by Metro Tunnel Excavation Considering the Influence of Group Piles

Considering the influence of group piles, a prediction model for three-dimensional ground surface settlement induced by circular metro tunnels excavation in incompressible rock masses is proposed based on the stochastic medium theory and the shear displacement method. The surface settlement caused by the metro tunnel opening is divided into two parts. One part is soil mass settlement caused by the metro tunnel opening and calculated by the stochastic medium theory. The other part is the settlement induced by the friction force between the group piles and the soil mass around the metro tunnel cross section and calculated by the shear displacement method. The three-dimensional prediction of the ground surface settlement is obtained by the linear superposition of the two parts. The validation of the proposed prediction approach is proved by comparing with the measured data and the numerical model of the double tunnels under thePuyuanoverpass where metro tunnels undercrossed group piles. The effects of buried depth, radial convergences, center distance of double tunnels, position and size of piles, and group piles are analyzed and discussed. The improved prediction approach can be applied to calculate the three-dimensional ground settlement, especially for the metro tunnels crossing through group piles.

Analysis of the Settlement in Rigid Pile Composite Foundation

On the basis of rigid pile composite foundation mechanism, This paper makes assumptions and establishes settlement calculation models, then applies shear displacement method to solve interaction flexibility coefficient of the pile-soil system and raises a rigid pile settlement calculation method, considering the effect of cushion.By calculating a certain experiment, it was found that theoretical and measured values of the relative error is smaller ,which can provide a reference for settlement calculation of rigid pile composite foundation in engineering.

Shear Displacement Method of Grouted Pile

Shear displacement method is used to predict the settlement of the grouted pile in this paper. An empirical relationship is used to determine the improvement of shear modulus for the soil around the grouted pile. A parameter is also proposed to represent the improvement of the shear modulus for the grouted soil at the pile tip. Shear displacement method is modified to consider the influence of grouting. The detailed calculation process of the method is described and determine of the parameter is also given in the paper.

Analysis of Single Pile Settlement in Layered Soils Based on Shear Displacement Method

Based on the theory of shear displacement method, the transfer matrix of pile in layered soils was deduced, so the analytical theory of settlement of single pile in layered soils is established, which can take into account the nonlinear influence of soils, and with which settlement, distribution of axial force, displacement and skin resistance of single pile along the depth in layered soils can be easily attained. By contrast with the practically measure data, it can be seen that the method proposed in this paper is simply and comparatively accurate in calculating the pile settlement under working load.

A Modified Shear Displacement Method for Calculating Settlement of Single Pile

A modified shear displacement method is presented to analyze the load-settlement response of a single pile in homogenous soil using two models. One model adopts a hyperbolic model to simulate the stress-strain relationship of soil under shear stress before failure occurs, and the other model uses a non-linear stress-strain relationship to evaluate the load-displacement behavior of the soil beneath the pile base. Comparisons of the load-settlement responses between the present modified model and the model suggested by Randolph and Wroth are given to demonstrate the effectiveness and accuracy of the proposed modified method.

Nonlinear Analysis of Interaction of Superstructure-Pile-Raft-Soil System in Layered Soil — Part I: Formulation of Interaction Equation

The layered soil model is used to simulate the nonlinear performances of the layered soil in this paper. Using the shear-displacement method, the flexibility coefficients of the pile-pile and the pile-soil are deduced based on the interaction mechanism of the pile-pile and the pile-soil in the layered soil. After that, the stiffness matrix of the pile-soil system can be established. Using coupling method presented in this paper, the interaction equation of superstructure-pile-raft-soil system is formulated. The interaction equations are used to analyze the reaction force on the pile head and the displacement characteristics of the raft of the piled-raft foundation in the layered soil and its practicality is excellent.