阳山隧道高地应力近水平岩层变形控制关键技术研究

阳山隧道是蒙华铁路的重难点控制性工程,2号斜井正洞小里程方向穿越高地应力近水平岩层,在施工过程中出现初支变形、底板隆起,甚至出现垮塌,严重影响了隧道施工安全。针对阳山隧道2号斜井正洞小里程方向高地应力现场表现情况,确定了该段地应力测试结果,采用了微台阶与限阻器相结合的施工工法,通过对典型断面初支拱顶下沉、水平收敛情况监测分析,发现限阻器变形可以吸收来自围岩的构造应力,消除了高地应力引起的初支拱顶开裂剥落、格栅钢架扭曲变形等病害。研究结果表明,该工法是阳山隧道高地应力近水平岩层变形控制关键技术,为后期同类隧道施工提供了宝贵的施工经验。

Study on Key Technologies of Deformation Control of Nearly Horizontal Rock in Yangshan Tunnel with High Geostress

Yangshan Tunnel is the important and difficult control project for Monghua Railway,small-mileage direction of No.2 inclined shaft passes through nearly horizontal rock formation with high geostress.During the construction process,the initial support deformation,the bottom plate uplift and even collapse have seriously affected the safety of tunnel construction.In view of the high geostress in the small mileage direction of No.2 inclined shaft in Yangshan Tunnel,the results of the geostress test are determined.A method of microstep combined with the limited rheostat is adopted in the construction.Based on the monitoring and analysis of the initial arch subsidence and horizontal convergence for the typical section,it is found that the rheostat deformation can absorb the structural stress from the surrounding rock and eliminate the cracking of the initial arch dome and distortion of the grid steel frame caused by the high geostress.The research results show that the construction method is the key technology to control the deformation of the nearly horizontal rock strata in Yangshan Tunnel,which could provide valuable experience for the later similar tunnel construction.