考虑非饱和粘性土含水量变化的地铁隧道围岩土体稳定性分析

含水量是非饱和土力学性质的重要控制因素,非饱和粘性土是北京地铁苏州街车站隧道的主要围岩土体类型,应用钻孔取样的方法取得隧道周边区域内的土体系统样本,通过三轴试验和含水量测试建立了非饱和粘性土围岩的变形和强度参数与含水量的相关性,进而明确了该工程场地非饱和粘性土的主要参数与含水量的关系,以此为基础确定了工程场地不同区域的土体力学参数,通过有限元数值分析方法研究了施工过程中的围岩土体稳定性与地表沉降量,明确了考虑土体含水量变化条件下的隧道开挖施工过程中的围岩土体稳定性状况。

NUMERICAL STABILITY ANALYSIS OF THE UNSATURATED CLAYEY SOILS SURROUNDING SUBWAY STATION TUNNEL UNDER CONSTRUCTION BY TAKING INTO CONSIDERATION OF SOIL MOISTURE CONTENT VARIATIONS

The mositure content is an important controlling factor of the mechanical property of unsaturated soil.The main kind of soil mass surrounding Beijing Suzhoujie Subway tunnel is unsaturated cohesive soil.By using the method of drill sampling the samples of the soil mass system around the tunnel area were obtained.The relationship between the deformation and strength and the moisture content of the unsaturated cohesive soil mass were established through triaxial tests.And furthermore the relationship between the main parameters and the moisture content of the unsaturated cohesive soil mass were established. Based on that,the mechanical parameters of the soils in different areas of the construction site were determined.Through the analytical method of finite element numerical modeling,the stability of the soil mass and the ground settlement during the construction were studied.And the stability of the soil mass during the construction of tunnel with the consideration of the moisture content variation were made clear.