摩擦型单桩承载性能设计理论研究

进一步分析了摩擦型单桩承载性能，建立了复杂介质中摩擦型单桩的地基-桩-土体系模型，将线性变形层模型和非线性传递函数模型相结合，以改进的适合于分层介质内的Mindlin解答为基础，给出了按摩擦型单桩承载机理分析计算的“广义弹性理论法”；同时，利用等效模量的概念解决了Mindlin解中土体位移为负值的现象，为桩基础设计计算提供了有力的理论依据。编制的计算程序，不仅可用于计算单桩竖向加载时的沉降值，而且可根据静载试验实测的荷载-沉降数据反演分析桩侧和桩端土的岩土力学参数值，可用于指导设计和施工，以弥补静载试验抽样率低的缺陷。对工程实例进行计算分析，结果显示，该种理论方法对于摩擦型单桩的计算具有较高的精度和实用性。

STUDY ON BEARING PERFORMANCE OF FRICTION PILE FOUNDATION IN COMPLICATED SOIL-LAYERS

Interaction mechanism of piles and soil for friction piles is studied in this paper. A new pile-soil system model, which considers the complexity of surrounding soil and the bearing strata, is established. An improved Mindlin integrate equation, which combines the nonlinear transfer function model and the linear deformation layer model, is put forward. Based on it, a method for design and calculation of the bearing capacity of friction pile foundation and with the relative movement between pile and adjective soil taken into account is set up. Equivalent module is defined to solve the problem of negative settlement in the ground. Load-settlement curves given by this method and calculation results are compared with that of field measurements. It is demonstrated that the new theory produces agreement with the measurement information. The optimization and back analysis method is used to analyze the geotechnical parameters of pile-soil system on the basis of field measured load-settlement curves. This parameters given by the analysis can be used to direct the design of piles foundation in the same type of soil-layers. This method can be used in the situations where ultimate bearing capacity can not be given by load test or the load test can not be carded out.