基于离散元强度折减法的大跨隧道稳定性研究

Study on the Stability of Large-Span Tunnel by Distinct Element Based Strength Reduction Method

节理面作为岩体中普遍存在的软弱结构面,对隧道围岩的稳定性影响较大,在节理较多的大跨隧道施工中,更容易发生拱顶掉块、塌方、滑移等灾害。基于此,文章依托贵阳市南垭路三号隧道,基于离散元强度折减法,采用3DEC软件对不同节理倾角、间距、组数以及衬砌参数情况下的隧道安全系数进行分析,评价了各因素对隧道稳定性的影响。结果表明:节理倾角越大、分布越密集、节理组数越多,隧道的整体稳定性越差;在单组节理的岩体中,节理倾角是影响隧道稳定性的主要因素;喷混凝土层对隧道的整体稳定性提升显著,10 cm厚喷层即可比裸洞的安全系数提高17.9%,并据此提出了隧道衬砌参数的优化建议。

As the weak structural surface of rock mass,the joint plane significantly affects the stability of tunnel surrounding rocks,and the chip off-falling at crown,collapse and slippage are more likely to occur for the largespan tunnel with many joints.Taking the Nanyalu No.3 tunnel in Guiyang as the background,it analyzes the safety factors in conditions of different joint angles,joint spacings,set numbers and lining parameters by distinct element based strength reduction method in 3DEC software,and evaluates the effects of various factors on tunnel stability.The results show that the larger the joint angles and the joint set numbers and denser the joints,the more unstable the tunnel;the stability of tunnel is mainly effected by the joint angle for the rock mass with single set of joint;sprayed concrete layer significantly improves the tunnel stability,the safety factor of the tunnel with lining thickness of 10 cm is improved by 17.9%compared with that without any lining structure,and some optimization suggestions for the tunnel lining parameters are proposed in light of this.