跨管状垂直落水溶洞隧道施工变形分析及加固措施

Construction Deformation Analysis and Reinforcement Measures of Cross-tubular Vertical Karst Cave Tunnel

岩溶区隧道施工会遇到溶洞的侵入,威胁施工安全。以实际工程为背景,采用数值模拟的方式研究垂直落水溶洞对隧道开挖及支护结构的影响,并提出隧道加固措施。研究结果表明,隧道开挖过程中,临近隧道的溶洞壁会存在向洞内坍塌的趋势,施工存在一定的坍塌风险;受围岩偏压的影响,初期支护出现了向溶洞内“挤入”的变形,增加了初期支护隧道纵向方向的压应力,隧道仰拱处出现弯折变形;二次支护结构变形量较小,但仍存在沿溶洞轮廓发生变形的情况。结合模拟计算结果,提出了仰拱底部设置钢筋混凝土板、衬砌结构优化、施加护拱的加固措施及优化排水的措施保障工程安全,通过现场监测验证了加固结果,该研究可为同类型工程提供参考。

Tunnel construction in karst areas can encounter intrusion of caves,which threatens construction safety.In this paper,numerical simulation is used to study the effect of vertical water fall caverns on tunnel excavation and support structure in the context of actual projects,and to propose tunnel reinforcement measures.The results show that during the tunnel excavation,the cavern wall near the tunnel will have a tendency to collapse into the cavern,and there is a certain risk of collapse;influenced by the partial pressure of the surrounding rock,the initial support appears to squeeze into the cavern deformation,increasing the compressive stress in the longitudinal direction of the initial support tunnel,and the bending deformation at the elevation arch of the tunnel.The deformation of the secondary support structure is smaller,but there is still deformation along the cavern profile.Combined with the simulation calculation results,we proposed the reinforcement measures of lining structure optimization,imposing arch protection,setting reinforced concrete slab at the bottom of the elevation arch and optimizing the drainage to strengthen the tunnel,and the reinforcement results were verified through field monitoring,and this study can provide reference for similar projects.