黄土损伤模型及其在隧道施工稳定性分析中的应用

Statistical Constitutive Model of Loess Damage and Its Application in Tunnel Stability Analysis

为了更加正确合理地对黄土隧道施工的围岩稳定性进行判别,建立了黄土的损伤统计本构模型,并提出了一种判别隧道施工稳定性的极限应变法。假设黄土微元强度分布服从复合幂函数,基于连续介质损伤力学理论以及等效应变理论,同时考虑围压和含水量对黄土变形模量的影响,利用统计学的方法建立了一个能够反映不同含水量和不同围压条件下黄土应力应变关系的本构模型。经验证,建立的模型可以较好地反映黄土在受荷全过程中的应变硬化特性,尤其是在低围压条件下的应变软化特性。通过本文所建立的黄土损伤统计本构模型,在原有的围岩极限应变判断法基础上对围岩界限应变求解公式进行修正,最终提出了一个适用于黄土地层的隧道施工稳定性判别方法,并将其应用于实际工程中。

In order to judge the stability of surrounding rock in loess tunnel construction more correctly and reasonably,a statistical constitutive model of loess damage is proposed,and a limit strain method is proposed to judge the stability of tunnel construction.In this paper,it is assumed that the strength of loess micro elements is subject to composite power function,and the continuum damage mechanics theory and equivalent strain theory are used as the modeling basis.Meanwhile,considering the influence of confining pressure and water content on the deformation modulus of loess,a new constitutive model which can reflect the stress-strain relationship of loess under different water content and different confining pressure is established by using statistical method.The results show that the model established in this paper can well reflect the strain hardening characteristics of loess during the whole loading process,especially the strain softening characteristics under low confining pressure.Based on the statistical constitutive model of loess damage established in this paper,the formula for determining the limit strain of surrounding rock is modified on the basis of the original method for determining the limit strain of surrounding rock.Finally,a method for determining the stability of tunnel construction in loess stratum is proposed and applied to practical engineering.