托换支护法中托换桩变形影响因素的数值分析

Numerical analysis of effect of underpinning pile on excavation bracing

"托换支护法"是近年来新兴的紧邻既有建筑物基坑开挖的一种基坑支护方法。其工作原理是根据建筑物的重量、地基土的工程性质、可能产生破坏的范围,以荷载传递和应力转移的原理为指导思想,通过托换桩直接限制临近建筑物的竖向变形,托换桩与水平构件土钉一起承担侧向土压力,从而达到减沉、抗倾的目的。以深基坑托换工程为研究对象,并采用FLAC有限差分软件进行数值模拟,以此来研究分析托换支护法中托换桩内力和变形的影响因素。通过FLAC3D的模拟分析可知:上部荷载的大小、托换桩的长度,开挖深度,托换桩嵌固深度是影响托换效果的主要因素。

＂Underpinning pile method＂ is a new technique to carry on the excavation bracing in recent years when the building is adjacent to the existing excavation of a foundation pit.Its principle is based on weight of the building,soil engineering property,probable destruction type and extension and its guiding theory is load transfer and stress transfer theory.The underpinning piles could directly restrict the vertical displacement of adjacent buildings and bear lateral earth pressure.The piles and soil nails together attach the purposes of anti-subsidence and anti-leaning.FLAC（fast lagrangian analysis of continua）simulation is used to study the effect of underpinning pile method on the stress and the deformation of underpinning piles.Through finite-difference analysis,it is found that the main factors are the size of superstructure loads,the length of the underpinning pile,excavation depth and the mounted depths of the pile.