城市富水地层大型地下空间管幕冻结规律模型试验研究

为解决管幕+冻土复合结构在大体量冻结工程应用时冻胀规律不明确、控制效果不稳定等难题，基于上海轨道交通18号线江浦路车站管幕冻结暗挖工程进行了开放系统下的模型试验。通过对不同影响因素下的管幕冻结冻胀特性和管幕受力规律进行试验研究，得出以下结论： 1）管幕可以对冻胀产生较好的约束作用，管幕+错峰冻结可以有效避免上覆土体及结构抬升； 2）间歇冻结后管幕受力曲线根据间歇时间呈现规律性锯齿波动，停冻3、5、7 d后，管幕所受冻胀压力分别可以减少约40、50、60 MPa，表明采用间歇冻结可以有效降低冻胀压力； 3）上覆地层压力越大，管幕受冻胀压力越小，较大的上覆压力可以约束冻胀的发展。

Model Experiment of Freezing Law of Pipe Roof Usedin Large Underground Spaces with Water Rich Layer

An open system model experiment is conducted on the pipe roof freezing and mined project of Jiangpu road station on Shanghai metro line 18 to investigate the frost heave law and control effect of freeze sealing pipe roof composite structure in large scale freezing projects. Similar simulation experiments are conducted to study the freezing and frost heave characteristics of the pipe roof and the force law of the pipe roof under various influencing factors. The results reveal the following: (1) The pipe roof can restrain the frost heave well, and the pipe roof freezing and peak freezing can effectively prevent the lifting of upper soil and structure. (2) The pressure curve of the pipe roof shows regular sawtooth fluctuations with freezing time after intermittent freezing. After 3, 5, and 7 days of intermittent freezing, the frost heave pressure on the pipe roof reduce by approximately 40, 50, and 60 MPa, respectively, indicating that the method can effectively reduce the frost heave pressure. (3) The pipe roof′s frost heave pressure decreases with increasing upper pressure. Therefore, a larger upper pressure can restrain the development of the frost heave.