高地应力深埋隧道断裂破碎带段大变形控制现场试验研究

丽香铁路中义隧道出口平导玉龙雪山西麓断裂破碎带段围岩软弱、破碎,受高地应力及断裂破碎带影响严重,边墙大变形灾害突出,以此为研究背景,开展了4种围岩大变形控制措施的现场试验研究。试验结果表明:采用普通加强支护措施(工况1),无法控制该段围岩变形;采用"抗放结合"控制措施,下部围岩应力释放需缓释,采用工况3(双层支护+下台阶、仰拱分开施作)方案,试验段围岩应力得到较好控制,但其工序繁琐,施工进度缓慢;采用"强支"理念的工况4(单层支护+加强拱架+预留应急加固措施)方案,最大日变形速率、累计最大变形量均最小,分别为3.2 cm/d和62.2 cm,试验段全长围岩累计变形量在可控范围内,施工工序较为简单,施工月进尺可达90 m以上;考虑到平导需发挥超前作用,建议中义隧道出口平导玉龙雪山西麓断裂破碎带段采用工况4方案进行施工。研究结果可为类似工程提供参考。

Field tests on large deformation control measures of surrounding rock of deep tunnels in fault zones with high geostress

The surrounding rock at the western piedmont of Yulong Snow Mountain fault zone of Zhongyi pilot tunnel at the tunnel exit of the Lijiang-Xianggelila railway is weak and fractured affected by the high geostress and fault zone, and the large deformation of the side wall is prominent. Four kinds of large deformation control measures for the surrounding rock are taken out in the field tests. The results show that the deformation of the surrounding rock is out of control adopting the general strengthening support measures (working condition 1). It needs slow release adopting control measures of resisting and reducing the stress of the surrounding rock. The stress of the surrounding rock of the test section is better controlled by working condition 3 (double-layer support + lower bench and inverted arch excavation), but the process is tedious and the construction progress is slow. Adopting the "strong support" measure of working condition 4 (monolayer support + strengthening arch support + reserved emergency reinforcement measures), the maximum daily rate of deformation and the maximum accumulation of deformation are the minimum, 3.2 cm/d and 62.2 cm respectively, the accumulation of deformation of the full test section is within the controllable range, the construction procedure is relatively simple, and the advance progress of the construction month can reach more than 90 m. In view of the advance effect of the pilot, It's highly recommended that the western piedmont of Yulong Snow Mountain fault zone of Zhongyi tunnel exit should adopt the working condition 4. The research results can provide a reference for large deformation control measures for the surrounding rock of deep tunnels in fault zones with high geostress.