侧部岩溶隧道围岩与支护结构力学特性分析

Analysis on mechanical characteristics of surrounding rock and support structures of lateral karst cave tunnel

岩溶区隧道因受岩溶的影响,其围岩与支护结构力学特性与一般隧道存在较大区别。以忠垫高速公路某岩溶隧道为背景,采用三维快速拉格朗日法,对侧部岩溶隧道施工过程中的围岩位移、应力、塑性区和锚杆轴力及喷混凝土层力学特性进行研究,并将计算结果与现场监测结果进行了比较分析。结果表明,隧道开挖后,围岩分别向溶洞和隧道内变形,溶洞与隧道之间的围岩向两个相反的方向变形。塑性区主要集中在隧道的周围和溶洞的左右侧部。隧道与溶洞之间的围岩应力集中程度较高。靠近溶洞侧的锚杆轴力及喷混凝土层轴力和弯矩要比其他位置的相应值都要大。

Because of the influence of karst cave, mechanical characteristics of surrounding rock and support structures of tunnel in karst zone differs from that of common tunnel. Taking a karst cave tunnel in the Zhongdian Expressway as an example, surrounding rock displacement and stress and plastic zone and anchor axial force and shotcrete axial force and moment are studied by using the three-dimensional fast lagrangian analysis of continua method, and the numerical calculation results and field monitoring results are compared. The results indicate that after tunnel is excavated, surrounding rock is convergented toward karst cave and tunnel. The surrounding rock between karst cave and tunnel is convergented in opposite direction. Plastic zone mainly concentrate on around tunnel and left-side and right-side of karst cave. The degree of stress concentration of the surrounding rock between tunnel and karst cave is higher. The anchor axial force and shotcrcte axial force and moment of near karst cave are larger than that of away from karst cave.