富水岩溶地层隧道仰拱隆起原因分析及控制研究

Cause Analysis and Control of Tunnel Invert Uplift in Water-rich Karst Stratum

贵州DJ隧道在穿越富水岩溶地层时出现仰拱隆起及开裂渗水,危及隧道结构及运营阶段行车安全,采用雷达探测以及现场情况调查对其进行病害原因分析,进而提出相应的整改措施,同时采用现场监测技术对仰拱拆换后受力情况及隧道外侧水压进行实时监测。结果表明:隧底水压过大、围岩遇水软化以及围岩溶洞是造成该隧道仰拱隆起的主要原因;采用“注浆钢花管+仰拱拆换+排水沟加宽+设置泄水孔+增设排水系统”的整治措施能有效治理仰拱病害;仰拱进行整治后二衬钢筋混凝土的接触应压力及钢筋应力远小于安全允许值,隧道外侧水压较小,且在运营荷载作用下结构受力稳定,说明仰拱整治方案合理有效。

When crossing the water-rich karst stratum,Guizhou DJ tunnel has inverted arch uplift,cracking and water seepage,which endangers the tunnel structure and driving safety in the operation stage.The disease causes are analyzed by radar detection and field investigation,and then the corresponding rectification measures are put forward.At the same time,the field monitoring technology is used to monitor the stress of inverted arch and the water pressure outside the tunnel in real time.The results show that the main reasons for the uplift of the inverted arch of the tunnel are the excessive water pressure at the tunnel bottom,the softening of the surrounding rock when encountering water and the karst cave in the surrounding rock.The treatment measures of“grouting steel flower pipe+inverted arch removal and replacement+widening of drainage ditch+setting drainage hole+adding drainage system”can effectively control inverted arch diseases.After the treatment of the inverted arch,the contact stress and reinforcement stress of the secondary lining reinforced concrete are far less than the safety allowable value,the water pressure outside the tunnel is small,and the stress of the structure is stable under the action of operating load,indicating that the inverted arch treatment scheme is reasonable and effective.