复杂地质条件下大埋深隧洞衬砌与围岩协同作用#br# 物理模型试验研究

围岩-支护协同作用是地下工程支护结构设计的核心问题，关乎着地下工程建设的成败。为揭示深埋隧洞围岩与支护结构协同作用机理，以滇中引水最大埋深约1512m的香炉山隧洞为研究背景工程，首次开展复杂地质条件下深埋隧洞衬砌与围岩协同作用真三维地质力学模型试验，真实再现隧洞开挖与支护的施工全过程。模型试验研究表明：1）不同地质条件下隧洞围岩的应力释放过程不同，硬岩隧洞围岩应力释放速率先慢后快，软岩隧洞应力释放速率先快后慢；2）不同地质条件下隧洞衬砌与围岩接触压力的分布形式不同，硬岩隧洞最大接触压力位于拱肩，软岩隧洞最大接触压力位于拱顶；3）衬砌与围岩协同作用包括两种应力释放机制、3个施工阶段和4种承载状态；4）不同地质条件下隧洞衬砌施作后围岩和衬砌承担的荷载比例不同，硬岩隧洞围岩平均承担约85%的荷载，衬砌约承担15%的荷载，软岩隧洞围岩平均承担约25%的荷载，衬砌承担约75%的荷载。

Physical model test study on synergistic action of lining-rock for deep tunnel under complex geological conditions

 The synergistic action of surrounding rock and support is the core issue in the support design of underground engineering, which is closely related to the success or failure of underground engineering construction. In order to reveal the synergistic mechanism of rock and support in deep tunnels, the true 3D geo-mechanical model test for the synergistic action of lining and rock mass under complex geological conditions was conducted for the Xianglushan tunnel in the Central Yunnan Water Diversion Project, so that the whole process of tunnel excavation and support is truly reproduced. The model test results indicate that(1) The stress release processes of surrounding rock around the tunnel are different for different geological conditions. The stress release rate of surrounding rock in hard rock is slow at first and then tends to be quicker, but in soft rock, it is quick at first and then tends to be slower; (2) the distribution patterns of the contact pressure between the lining and the surrounding rock are different for different geological conditions. For hard rock, the maximum contact pressure is located at the spandrel, but in soft rock the maximum contact pressure is located at the vault; (3) During the process of tunnel construction, the synergistic action of lining-rock includes two types of stress release mechanisms, three construction stages and four load bearing states; (4) For different geological conditions, the load bearing ratio of the surrounding rock and lining is different after the construction of tunnel lining. For hard rock, the surrounding rock may bear about 85% of the total excavation load, and the lining may take about 15% of the total excavation load; for soft rock, the surrounding rock may bear about 25% of the total excavation load, and the lining may take about 75% of the total excavation load. The model test results can provide important test references for the development of the construction scheme and the optimization of support design in deep tunnel under complicated geological conditions.