深基坑支护体系冻胀变形及控制三维数值分析

针对季节冻土区越冬深基坑工程,着重分析由于土体冻胀而导致的支护结构异常变形问题,基于哈尔滨地铁3号线某车站深基坑工程实例，利用ABAQUS有限元分析软件建立基坑的三维有限元模型，模拟其开挖施工的全过程，并将分析结果与实际监测数据进行对比，验证了模型的合理性；使用FORTRAN语言对ABAQUS软件进行二次开发，建立土体的冻胀与温度场之间的函数关系，模拟了深基坑越冬过程中由于外界温度改变而导致的基坑土体冻胀变形、围护结构位移及内支撑轴力变化。提出了在基坑侧壁贴设保温板以控制土体冻胀的防护措施，并以墙身位移和内支撑轴力为指标分析不同厚度的防火型XPS板对基坑保温效果的影响，最后给出了贴设保温板的经济厚度，为今后类似工程提供了参考。

Numerical analysis on frost heave deformation and control for retaining system of deep foundation pit

Aiming at the overwintering deep foundation pit in the seasonally frozen soil area, the abnormal deformation of support structure caused by frost heave of soil was analyzed. Based on the deep foundation pit of a station in Harbin Metro Line 3, a three-dimensional finite element model of foundation pit was established. The whole construction process of foundation pit excavation was simulated, and the rationality of the model was verified by the actual monitoring data. The relationship between the frost heave and the temperature field of the soil was found by using the developed ABAQUS with FORTRAN language. The frost heave deformation of soil, the displacement of the retaining structure and the axial force change of the internal support were simulated in the process of deep foundation pit overwintering due to the change of temperature. Amethod was proposed to control the frost heave of soil by installing thermal insulation board on the side wall of foundation pit. By analyzing the influence of different thickness of fire resistant XPS board on the thermal insulation effect of foundation pit, the economic thickness of the insulation board was given, which can provide reference for similar projects in the future.