群桩沉降计算理论分析

基于Geddes应力解，并根据叠加原理计算群桩内任意点处的三向应力，采用基于Duncen-Chang本构模型的修正分层总和法计算群桩内任意点处的沉降量，最后，根据基点法1]和群桩基础荷载、变形协调关系建立方程，从而，最终获得群桩的沉降计算。该理论较常规弹性理论方法计算群桩沉降有较大地改进，具体体现在以下几个方面：（1）考虑了群桩中地基土的三向应力分布对群桩沉降计算的影响；（2）考虑了土体本构模型（Duncen-Chang弹性非线性本构模型），因而，能计及土体非线性特性对群桩沉降的影响；（3）采用修正分层总和法理论，能考虑土体成层分布特性以及侧向变形对单桩沉降计算的影响。

Analysis of settlement of group piles

Based on Geddes stress solution, calculating 3-D stress of arbitrary point in group piles according to superposition principle ,and based on Duncen-Chang constitutive model, to calculate settlement of arbitrary point in group piles according modified layered summation. Then, establishing set of equations according to basic point methodl] and coordinative relationship of loading and deformation of group piles foundation, to obtain the loading-settlement relationship of group piles. To compare with general method based on Geddes stress solution, three parts have been improved, they are as followings: (l)adopting Geddes 3-D stress solution, its effect on settlement of group piles can be calculated;(2)the constitutive model(Duncen-Chang model) is used to study the settlement of pile, the nonlinear character of soil can be considered.;(3)using modify layered summation, the layer character and lateral deformation of soil can be computed. Therefore, the method that proposed in this paper is more perfect in theory, amount calculation is moderate and apply to engineering practice.