引汉济渭工程隧洞施工若干技术问题探讨

基于引汉济渭工程隧洞施工实际,结合我国现有技术规范要求,对比分析了引汉济渭工程隧洞动态设计、超前地质预报、隧洞开挖方式、隧洞支护时效及衬砌与掌子面距离等五个方面的问题,得到了适宜引汉济渭工程隧洞施工特点的动态施工技术方法。针对不同围岩条件实施隧洞动态设计,采用了不同的开挖和支护方式。对物探发现的异常区进行钻探验证,以提高地质超前预报及涌水预测精度。地质复杂区段按照"物探先行,钻探验证,有掘必探,先探后掘"的原则组织施工。在实际施工中,应提倡利用围岩在无支护条件下的允许暴露时间也就是围岩的自稳时间实现短距离的掘进与支护分离。对硬岩(Ⅰ—Ⅲ)围岩采用"钻爆设计、光爆施工、工序组织、快速施工"的思路,对软岩(Ⅳ—Ⅴ)围岩采用"围岩量测、确保安全、遵守设计、按部就班"的思路。

Discussion on several technical problems of tunnel construction for Hanjiang-to-Weihe River Valley Water Diversion Project

Based on the actual construction of the tunnel for and combined with the existing relevant technical specifications in China， the problems from the construction of Hanjiang-to-Weihe River Valley Water Diversion Project in the five aspects， i.e. dynamic design， advance geological prediction， tunneling method， time-reliability of tunnel support and distance between lining and excavation face， are comparatively analyzed herein， and then the following methods of the dynamic construction technology adaptable for the construction characteristics of the project are obtained； i.e. different excavation and support methods are to be adopted for different conditions of surrounding rock； geo-drilling is to be made for the verification of the anomaly zone found out through the geophysical prospecting， so as to enhance the accuracies of the relevant advance geological prediction and the water burst prediction； the construction in the complicated geological zone or section is to be organized according to the principle of “geophysical prospecting is made in advance and then verified through geo-drilling subsequently， prospecting must be made in advance for all the excavations and then excavations are made subsequently”. During the actual construction， the utilization of the allowable exposed time， i.e. the self-stablized time under the unsupported condition must be recommended to be utilized for realizing the short distance separation between tunneling and support. Moreover， not only the idea of drill-blast design， smooth-blasting construction， working procedure organization and rapid construction is adopted for the surrounding rock composed of hard rock （I~III）， but also the concept of measuring surrounding rock， ensuring safety， complying with design and working step by step is adopted for the surrounding rock composed of soft rock （IN~V）.