关键词: 越冬基坑;水平冻胀力;数值模拟;正交试验;现场监测;

Abstract: For solving severe cold protection problems of foundation pits in freezing soil area，the variation laws of foundation pit temperature，horizontal displacement and horizontal frost heaving force during overwintering period were studied by simulating the deep foundation pit in Exhibition Center Station of Harbin Metro Line 3.Orthogonal experiments were carried out to explore the effects of cold end temperature，cooling time and retaining pile stiffness on the horizontal frost heaving force of the foundation pit.Based on this，targeted protection measures were put forward.The results show that the horizontal frost heaving force of foundation pit has a significant effect on the displacement of side wall.The horizontal frost heaving force at some positions of side wall exceeds the allowable value of the code.Besides，the cold ends temperature has the most significant effect on the horizontal frost heaving force.In order to meet the specification requirements，the cold ends temperature should be controlled above-13 ℃.The field monitoring results show that the deformation and overall stability of the foundation pit complies with the simulation results，and the effect of the thermal insulation measures designed according to the orthogonal experimental results is ideal.The research results can provide reference for the overwintering protection of deep foundation pit in severe cold area.

Key words: foundation pit construction during overwintering period；horizontal frost-heave forces；numerical simulation；orthogonal test；field monitoring