岩溶区小净距下穿隧道的泄水洞施工技术研究

Research on Construction Technology of Drainage Hole Passing Under the Tunnel at Small Clear Distance in Karst Areas

西南地区岩溶发育,地表水与地下水往往由溶隙连通,为有效解决柿子园隧道在雨季时大量涌水,影响后续铁路行车的运营安全,结合现场隧道正洞衬砌已施作完成,采取增设泄水洞将隧道周边围岩的岩溶富水、地表补给水集中引至泄水洞排出至洞外,而新增泄水洞需下穿隧道正洞。本文阐述了岩溶区新增泄水洞小净距下穿隧道正洞段的施工技术,包括泄水洞下穿段的断面优化、超前地质预报、大管棚超前支护、微小台阶非爆开挖、围岩注浆加固、加强支护与监控量测等,其中加强支护中采用了2项专利技术(自进式中空锚杆注浆头、锁脚锚管角度控制装置);通过采取这些技术措施,控制了正洞隧道衬砌结构的下沉,确保了施工安全,实现了新增泄水洞及既有隧道正洞衬砌的使用功能,相关经验值得借鉴。

Karst development occurs in the southwestern region,and surface water and groundwater are often connected by karst gaps.In order to effectively solve the problem of a large amount of water inflow in the Shiziyuan Tunnel during the rainy season,which affects the safety of subsequent railway operation,combined with the completion of the lining of the main tunnel on site,a drainage hole is added to concentrate the karst rich water and surface recharge water around the tunnel to the drainage hole and discharge it outside the tunnel.The newly added drainage hole needs to pass through the main tunnel.This article elaborates on the construction technology of the newly added drainage hole that passes under the main tunnel section at small clear distance in karst areas,including section optimization of the underpass section of drainage tunnel,advanced geological prediction,advanced support for large pipe sheds,non explosive excavation of small steps,surrounding rock grouting reinforcement,strengthening support and monitoring measurement,etc.Among them,two patented technologies(self advancing hollow anchor rod grouting head and locking foot anchor pipe angle control device)are used for strengthening support.By adopting these technical measures,the sinking of the lining structure of the main tunnel has been controlled,ensuring construction safety and achieving the functional use of newly added drainage tunnels and existing tunnel lining.The relevant experience is worth learning from.