开放系统下冻胀引起地表隆起变形预测的解析方法

Analytic method for predicting uplift deformation of ground surface induced by frost heave in an open-system

开放系统下土体冻胀引起土工结构变形致使其服役特性面临严峻挑战。基于土体冻胀非线性弹性力学模型,推导了计算半空间无限体中土单元在自重下冻胀的数学表达式,建立了水平场地土冻胀模拟方法,提出了考虑上部压载效应与位移边界变化的场地表面隆起位移及土体应力与应变的计算方法。在此基础上,利用开放系统下粉质黏土逐级降温冻胀室内试验,验证了冻胀引起地表隆起变形预测解析方法的可靠性。经验证,该变形预测解析方法可应用于寒区场地冻胀量的评估,进而为开放系统下土工结构物变形预测提供科学参考。

Considering the engineering design demand,a simple analytical method for calculating soil frost heave deformation of horizontal field under steady-state condition is established based on the nonlinear elastic mechanical model of soil frost heave. Mathematical expression to determine the frost heave of soil element in semi-infinite space body under dead weight is deduced. Also,the prediction methods of soil lifting displacement,soil stress and strain field under different overburden and displacement conditions of horizontal site are proposed. Furthermore,the step-freezing test of Harbin silty clay in open system is carried out,and the reliability of the analytical method for predicting the surface lifting deformation caused by frost heave is verified. Besides,the analytical method is further applied to the evaluation of the frozen site. It can be concluded that the frost heave amount can be used as a main quantitative index to evaluate the frost heave of the site. However,it is still necessary to consider the frost heave sensitivity,the thickness of the frozen soil layer,the initial overburden pressure and the surface temperature.