公路隧道跨越有压引水隧洞安全净距及措施

Safety net distance and measures for highway tunnel crossing diversion tunnel under hydrostatic pressure

考虑引水隧洞的静水压力,研究公路隧道选线时与既有引水隧洞安全净距及设计措施。同时分析新建公路隧道常规爆破振动对既有引水隧洞造成的结构影响和引水隧洞静水压力这两个因素,计算出立体交叉竖向安全净距;明确对既有引水隧洞有影响的新建公路隧道施工影响段落长度,并给出影响段落内的设计及施工措施建议。分析得出:竖向安全净距主要与围岩等级、开挖断面宽度、静水压力等有关;建议公路隧道上跨引水隧洞并且尽可能与其垂直;新建公路隧道交叉影响段落长度L=2×(2.4R_(1)+H+R_(2));新建公路隧道施工通过交叉影响段落时采用控制爆破、CRD法施工和径向注浆等措施后,可有效保证施工及既有引水隧洞安全。

Considering the hydrostatic pressure of the diversion tunnel,the safety net distance and design measures between the highway tunnel and the existing diversion tunnel during the route selection stage are studied.Taking into account both the structural impact of conventional blasting vibration on the existing diversion tunnel and the hydrostatic pressure of the diversion tunnel,the vertical safety net distance of the overpass is calculated.Clarify the length of the construction impact section of the new highway tunnel that has an impact on the existing diversion tunnel,and provide suggestions for design and construction measures within the impact section.Analysis shows that:The vertical safety distance is mainly related to the rock grade,exca-vation section width,hydrostatic pressure,etc.;It is recommended to cross the diversion tunnel on the highway tunnel and try to be perpendicular to it as much as possible;The length of the section affected by the intersection of newly-built highway tun-nels is L=2×(2.4R_(1)+H+R_(2));After adopting measures such as controlled blasting,CRD method construction,and radial grouting during the construction of new highway tunnels passing through cross affected sections,the safety of construction and existing diversion tunnels can be effectively ensured.