溶洞型隧道围岩不同因素下渗流规律研究

Study on Seepage Law of Surrounding Rock of Karst Tunnel Under Different Factors

为了研究溶洞型隧道围岩渗流规律,以宜万铁路野三关隧道为工程背景,根据工程资料和文献调研得出影响围岩渗流的关键因素,并采用RFPA软件建立基于弹性损伤的岩溶隧道渗流有限元计算模型,分析围岩裂缝形式、围岩渗透系数以及水压加载速度等因素下渗流规律,研究结果表明:围岩渗透系数、裂缝形式和水压加载速度对渗流产生显著影响,且影响作用依次减弱。随着水压增大,围岩裂缝演化过程主要分为平稳潜伏阶段、突发破坏阶段、加速发育阶段,裂缝破坏大致由裂缝末端沿裂缝走向呈发散式扩展,水压达到一定阶段后裂缝末端周围破坏单元数量激增,并不断密集贯通形成新裂缝,使原来的抵抗单元转变为薄弱单元,并最终形成优势渗流通路。

In order to study the seepage law of surrounding rock in karst tunnel,the key factors affecting the seepage of surrounding rock are obtained based on the engineering data and literature research,taking Yesanguan Tunnel of Yichang-Wanzhou Railway as the engineering background.RFPA software is used to establish the finite element calculation model of karst tunnel seepage based on elastic damage,and analyze the seepage law under the factors of surrounding rock crack type,surrounding rock permeability coefficient and hydraulic loading speed.The results show that the permeability coefficient of surrounding rock,crack type and hydraulic loading speed have significant effects on seepage,and the effects are weakened in turnꎻwith the increase of water pressure,the evolution process of surrounding rock fractures is mainly divided into stable latency stage-sudden failure stage-accelerated development stage.The crack failure is generally divergent from the end of the crack along the crack strike.When the water pressure reaches a certain stage,the number of failure units around the end of the crack increases sharply,and new cracks are formed continuously through intensive penetration,which changes the original resistance unit into a weak unit,and finally forms a dominant seepage path.