关键词: 拔出, 拔桩, 回填, 套管, 压入

Abstract: Effects of pile pulling on the surrounding structures is a common problem in construction projects. The effect can be reduced substantially if piles are pulled in casing. The overall process is divided into three stages including steel casing pressing, pile pulling, and steel casing pulling accompanied by refilling. We take an abandoned pile in Shanghai Rail Transit Line 7 as an example to study the effect on an established large waste pipe during pile pulling in casing. In the study, we use the general purpose finite element program ABAQUS based on the elastic stressstrain theory. The soil is simulated according to the Drucker-Prager elastic-plasticity stress-strain theory. It is shown that the horizontal and vertical displacement increases with the increase of casing depth during the pilepressing process, while with the decrease of casing depth during pile pulling process. The displacement of horizontal direction is one tenth of that of vertical direction. Comparison between the simulation results and the monitored data shows that the simulation is useful to the construction.

Key words:  pile pulling, backfill, casing, press, pull