高地应力深埋层状围岩隧道非对称变形受力机制研究

Study of Force Mechanism of Asymmetrical Deformation of Deep-buried Layered Surrounding Rock Tunnel under High Ground Stress

为深入研究高地应力层状围岩中隧道和支护结构的非对称变形受力特性和机制,以绵茂公路篮家岩隧道为工程背景,采用现场监测和数值模拟相结合的方法,研究不同层理角度和地应力方向下隧道变形、钢拱架应力以及二次衬砌弯矩和轴力的变化规律。结果表明:1)层状围岩中隧道结构受力的最不利位置常出现在层理面法向方向; 2)隧道的非对称变形机制在于地应力对层理面产生的法向挤压作用和切向滑移作用,当层理面角度缓倾时,隧道拱顶和拱底承受较大挤出变形,当层理面角度陡倾时,地应力方向与层理面夹角越小,隧道衬砌在主应力作用位置产生的滑移变形越大。最后,根据层状围岩隧道变形和衬砌受力特征,提出合理的支护优化措施。

In order to further study the force characteristics and mechanism of asymmetrical deformation of tunnel and supporting structure in layered surrounding rock under high ground stress,the variation rules of tunnel deformation,steel arch stress,and bending moment and axial force of secondary lining of Lanjiayan Tunnel on Mianzhu-Maoxian Highway under different stratification angles and ground stress directions are studied by field monitoring method and numerical simulation method.The study results show that:(1)The most adverse force position of layered surrounding rock tunnel usually exists in normal direction of stratification plane.(2)The asymmetrical deformation mechanism of layered surrounding rock tunnel is the normal squeezing action and tangential slip action of ground stress on stratification plane;when the angle of stratification plane is small,the crown top and invert of tunnel bear large extrusion deformation;and when the angle of stratification plane is high,the smaller the angle between ground stress direction and stratification plane is,the larger the slip deformation of position of tunnel lining under principal stress action is.The optimization measures are proposed based on the deformation and force characteristics of layered surrounding rock tunnel and tunnel lining.