寒区隧道围岩冻胀破坏临界温度计算模型

Calculating model of critical temperature for frost heave failure of tunnel surrounding rock in cold regions

为建立围岩不同尺度下缺陷冻胀起裂的破坏判据,根据弹性力学和断裂力学并结合冻胀力值得到宏细观缺陷发生冻胀破坏判据,建立含宏细观缺陷的寒区隧道围岩冻胀破坏临界温度的计算模型。依托大坂山隧道算例,分析不同参数对细观孔隙和宏观节理冻胀破坏临界温度的影响规律。结果表明:细观孔隙冻胀破坏临界温度随主干孔轴线直径增大而显著增大;而次孔轴线等效直径增大对临界温度的影响则较小,其主要作用是与主干孔形成主干-旁枝型孔隙结构。宏观节理冻胀破坏临界温度随节理长度和隧道断面半径增大而增大;随节理倾角增大先减小后增大,在倾角为40°时出现峰值临界温度。

In order to establish failure criterion for frost heaving of surrounding rock with defects at different scales,based on elasticity and fracture mechanics as well as frost heaving force value,the criteria for macro and micro defects were obtained,and a calculating model of critical temperature of tunnel surrounding rock with macro and micro defects in cold regions was established.Then,with Dabanshan tunnel as an example,influence of different parameters on critical temperature for frost heave failure of micropores and macro joints was analyzed.The results show that this temperature for micropore failure increases significantly with that of main hole axis diameter.However,increase in equivalent diameter of secondary pore axis has a smaller effect on the temperature,and its main function is to form a main-branch type pore structure with major pores.In terms of macro joints,its critical temperature increases with that of joint length and tunnel section radius.Moreover,it first decreases and then increases with the growth of joint inclination angle,with its peak critical value appearing at the angle of 40°.