【摘要】 在对骑跨于运营地铁隧道上的软土基坑施工中,常进行坑内和坑外深层搅拌桩加固,以控制基坑开挖变形保护下卧隧道。但搅拌桩施工本身会对土体结构进行扰动和破坏,产生挤土效应和超静孔隙水压力,从而影响下卧隧道结构。为此结合苏州星港街上跨地铁线工程,研究了改良的施工工艺和控制技术。分析提出了通过调整三轴搅拌桩水灰比、提升及下沉速率、加固水泥掺量等参数来优化搅拌桩施工工艺,并根据现场试验结果得到了合理的施工参数。更多还原

【Abstract】 In the construction of soft soil foundation pit over metro operation tunnels, the deep mixed pile in or out of foundation pit is usually reinforced to control the deformation of foundation pit during excavation and protect the underlying tunnel. But the mixed pile construction itself will disturb and destroy the soil structure, resulting in squeezing soil effect and ultra-static pore water pressure, which directly affect the underlying tunnel structure. In this paper, based on the Xinggangjie Street project in Suzhou City that crosses over metro lines, the optimized construction technique and control technology are studied. An improved three-axis mixed pile construction process is proposed, which adjusts the parameters of water-cement ratio, lifting and sinking rate as well as the cement content. Through the field test, reasonable construction parameters are obtained.更多还原