人工冻融软弱土融沉特性研究

Study on Thaw Settlement Behavior of Soft Frozen Soil

随着人工冻结法在地铁建设中的广泛应用,控制工后融沉已成为软弱地层冻结需要解决的难题.以苏州地铁典型软弱土层为研究对象,通过室内试验研究,得出不同补水条件下原状土开放融沉系数大于封闭融沉系数;融前卸载加压方式下,融沉系数随上部荷载增大呈指数型减小;无黏性重塑土融沉系数与原状土接近,黏性土重塑后融沉系数变大,其差值随该土灵敏度增大而增大;对于非饱和黏土和淤泥质粉质黏土,开放冻融条件下融沉系数与干密度变化关系均存在临界干密度,对应土体融沉系数最小.

With the extensive application of the artificial freezing method in subway construction,the thaw settlement controlling has become a problem to be solve in soft-soil freezing. The typical soft soil in Suzhou subway is taken as the research object. Related conclusions are obtained on the basis of the laboratory tests,which are as follows. The thaw-settlement coefficients with water supply are larger than those without,and it decreases exponentially with the increase of upper loads under the condition of loads removed before melting.The clay＇s thaw-settlement becomes larger after remolded and the difference increases with soil＇s higher sensitivity,while the non-cohesive soil has little change. As for the unsaturated clay and muddy silty clay,there existed a critical dry density between thaw-settlement coefficient and dry density change with water supply.And this corresponds to the minimum thaw-settlement coefficient.