复杂工程地质条件下深埋长隧洞应力场特征研究

穿越复杂工程地质条件的深埋长隧洞,应力场特征是目前工程建设关注的重点问题之一。针对巴基斯坦西北部某长隧洞引水式电站工程,基于水压致裂法对工程区3个钻孔进行地应力测试工作,根据测试结果主要分析了地形和断层对应力场分布特征的影响。依据工程地质条件建立三维有限元模型,结合实测地应力对工程区应力场特征进行回归分析,进而揭示了整个工程区地层浅部至深部应力量值的变化规律,并着重对尾水隧洞逆断层区的最大水平主应力方向进行研究,从机理方面探讨了断层区浅埋与深埋地层水平主应力方向的转化规律。研究结果对穿越断层区深埋长隧洞的设计和施工具有重要的工程指导意义。

Study on Stress Field Characteristics of Deep-buried Long Tunnel under Complex Engineering Geological Conditions

The stress field characteristics of deep-buried long tunnels crossing complex engineering geological conditions are one of the key issues in tunnel construction. In view of a long tunnel diversion hydropower project in Northwest Pakistan, the in-situ stress of three boreholes in the project was measured by hydraulic fracturing method. According to the test results, the influence of topography and faults about the distribution characteristics of stress field was analyzed. Based on the engineering geological conditions, the three-dimensional finite element model was established. Regression analysis of the stress field in the project area was carried out by using the measured in-situ stress, and the results of the regression analysis further revealed the variation law of stress magnitude from shallow to deep strata in the whole project area. This paper focused on the study of the maximum horizontal principal stress direction in the reverse fault area of tailrace tunnel. Based on the mechanism aspect, the transformation rules of horizontal principal stress direction in shallow and deep strata in the fault area were analyzed. The research results have important engineering guiding significance for the design and construction of deep-buried long tunnel across fault zone.