路基荷载下倾斜椭圆形空洞的稳定性评价及因素影响分析

Stability Evaluation of Inclined Elliptical Cavities Under Subgrade Loads and Factor Impact Analysis

为了防止严重威胁公路安全的采空区发生二次活化导致道路灾害,采用应力叠加法,将基于Boussinesq方程计算所得路基荷载下的附加应力场与初始应力场叠加,得到洞周任意一点的应力状态;利用Mohr-Coulomb强度准则得到空洞稳定性,通过与已有研究结果对比,验证稳定性评价的可靠性;利用二分法计算椭圆形空洞保持稳定时所能承受的最大路基荷载,并探讨路基荷载宽度比、路基荷载偏心距比、椭圆形空洞长短轴比和椭圆倾角等因素对椭圆形空洞稳定性的影响。结果表明:当椭圆形空洞长轴沿水平方向时,椭圆形空洞长短轴比和路基荷载的增大对椭圆形空洞造成应力集中效应叠加,使得最大路基荷载随长短轴比的增大而减小;当椭圆形空洞长轴沿竖直方向时,初始应力场与附加应力场引起的水平方向的应力集中效应互相削弱,含椭圆形空洞地基能承受更大的路基荷载。

To prevent road disasters caused by secondary activation of goafs seriously threatening highway safety,stress superposition method was used to superpose additional stress fields under subgrade loads calculated on the basis of Boussinesq equation with initial stress fields to obtain stress state at any point around the cavity.Elliptical cavity stability was assessed by using Mohr-Coulomb strength criterion,and reliability of stability evaluation was verified by comparing with previous research results.The maximum subgrade load that the elliptical cavities could remain stable was calculated by using dichotomy method,and influences of subgrade load width ratio,subgrade load eccentricity ratio,major-minor axis ratio of elliptical cavity,and elliptical inclination angle on elliptical cavity stability were discussed.The results show that when the major axis of elliptical cavity is along horizontal direction,the stress concentration effect of elliptical cavities caused by increases of major-minor axis ratio of elliptical inclination and subgrade loads is super-imposed,resulting in the maximum subgrade load decreases with the increase of major-minor axis ratio.When the major axis of elliptical cavity is along vertical direction,horizontal stress concentration effects caused by the initial stress field and the additional stress field weaken each other,and the foundation with elliptical cavities can withstand greater subgrade loads.