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寒区岩体工程含水孔(裂)隙中低温水冰相变会产生冻胀力与温度应力,岩体冻融损伤与断裂是由温度应力和孔(裂)隙中的冻胀力共同作用的结果。考虑温度应力对椭圆孔(裂)隙形变的影响,推导了椭圆孔(裂)隙中的冻胀力解析方程;基于最大拉应力准则,得到了低温热力耦合下椭圆孔(裂)隙周围最大拉应力与冻胀开裂角,建立了椭圆孔可简化为椭圆裂隙进行冻胀计算的临界条件;最后采用改进的等效热膨胀系数方法对隧道单裂隙围岩冻胀力与裂隙尖端应力场进行了数值分析。研究结果表明:(1)椭圆孔中的最大冻胀力与岩石的热膨胀性、裂隙倾角和裂隙长短轴比χ等因素有关;(2)长短轴比χ≥10的扁平椭圆孔可简化为裂隙进行计算分析,此时冻胀基本发生在裂隙尖端且尖端拉应力集中明显;(3)改进的等效热膨胀系数方法可以很好的模拟裂隙中的冻胀力与裂尖应力场。
Frost heaving force and temperature stress will occur in low temperature water-ice phase transition in water hole (crack) of rock mass in cold region. The freeze-thaw damage and fracture of rock mass are caused by temperature stress and frost heaving force in hole (crack) the result of. Considering the effect of temperature stress on the deformation of elliptical hole (crack), the analytical solution of frost heaving force in elliptical hole (crack) is deduced. Based on the maximum tensile stress criterion, the maximal elliptical hole (crack) Tensile stress and frost heave angle, the critical condition of elliptic crack can be simplified as elliptic crack frost heave expansion. Finally, the improved equivalent thermal expansion coefficient method is used to calculate the frost heave force and crack tip stress field of single-cracked tunnel in tunnel Numerical Analysis. The results show that: (1) The maximum frost heaving force in elliptical hole is related to rock thermal expansion, fissure dip angle and the ratio of χ and other factors. (2) The flat oval hole with ratio χ≥10 can be simplified as fissure At the same time, the frost heave basically occurs at the crack tip and the tip tensile stress concentration is obvious. (3) The improved equivalent thermal expansion coefficient method can well simulate the frost heave force and the crack tip stress field in the crack.