基于FLAC3D隧道超前孔卸压影响范围研究

Study on Influence Range of Pressure Relief of Advance Drilling in Tunnel Based on FLAC3D

针对西藏某隧道因花岗岩、片麻岩在高地应力条件下因围岩应力过大导致双护盾TBM开挖困难的实际情况,考虑采用超前钻孔卸压的方式使围岩应力减小以方便开挖,对超前钻孔影响的范围进行了研究。阐述了通过FLAC3D对超前钻孔进行数值模拟,对超前孔卸压影响范围进行分析的过程,得出超前孔对围岩压力影响的范围是其钻孔半径的5~6倍的结论。研究得出的超前孔卸压的影响范围,可为今后西藏高地应力条件下的TBM施工提供借鉴。

In view of the fact that it is difficult to excavate by double shield TBM due to the high ground stress of granite and gneiss in a tunnel in Tibet,the way of pressure relief in advance drilling is considered to reduce the stress in the surrounding rock to facilitate the excavation,and the influence range of advance drilling is studied.This paper describes the process of numerical simulation of advance drilling by FLAC3D and analysis of the influence range of pressure relief of advance drilling,it is found that the influence range of the advance drilling on the surrounding rock pressure is 5-6 times of its drilling radius.The influence range of the pressure relief of the advance drilling can be used for reference for the TBM construction in Tibet or under the conditions of high ground stress in the future.