岩溶隧道开挖对溶洞处治结构影响的数值模拟分析

Numerical simulation analysis of deformation effect on treatment structure of karst cave due to karst tunnel excavation

结合清连高速公路白须公特大岩溶隧道施工过程,采用三维有限元软件(ANSYS)对白须公隧道的处治结构与隧道开挖的相互作用进行了数值模拟。以隧道开挖中处治结构和围岩稳定性为研究对象,从而分析处治结构在隧道开挖过程中的受力特性,以及隧道围岩在隧道开挖过程中的位移。通过计算结果,对处治结构在岩溶隧道中的支护效果进行了评价,采用桩-承台-单边支撑墙-联系梁的处治方式是安全可靠的。在隧道开挖过程中,开挖面附近的桩基应变、支撑墙压力都加速变大,随后逐渐稳定,说明处治结构承担了一部分围岩压力,在岩溶隧道施工开挖中发挥了重要作用。分析结果与工程实测数据比较吻合,可为隧道穿越大型溶洞提供设计和施工方面的借鉴和参考。

According to a big karst cave in highway tunnel engineering of Qing-Lian Expressway in Baixugong, a three-dimensional element software （ANSYS） was employed to simulate the interaction between tunnel excavation and treatment structure in Baixugong tunnel. Stability of treatment structure and surrounding rock during tunnel excavation is studied in order to analyze the mechanical characteristics of treatment structure and the displacement of surrounding rock during tunnel excavation. According to analysis of calculation results, the pre-support effect of treatment structure in karst tunnels is evaluated. Treatment mode using pile-pile cap-one-wall support wall-connection beam, is safe and reliable. In the process of tunnel excavation, the pile strain and support wall stress all increased largely during the advance of excavation face, then gradually stabilized; and the treatment structure bears a part of surrounding rock pressure, it plays a support action role in karst tunnel excavation. The results are in good agreement with the field test data, so as to offer for reference in design and construction ofttmnels crossing a big karst cave.