摘要
引江补汉工程是南水北调后续工程的首个开工建设项目,其引水隧洞穿越了蠕滑型活动断裂-通城河断裂,研究活动断裂近场地应力特征对工程稳定性具有重要意义。选择较为复杂的通城河活动断裂近场区内开展了原位地应力测试及断裂构造稳定性分析,揭示断裂构造内现今地应力状态及断裂构造滑动失稳临界条件。通过在通城河活动断裂近场2个千米级深孔进行原位水压致裂法地应力测试。最后,基于实测地应力资料,结合库伦摩擦滑动准则及Byerlee定律对活动断裂稳定性进行了分析。结果表明:测试范围内存在应力分区,并推测以潜在转换深度900±20 m为界,空间主应力状态呈现由复合型(逆断型与走滑型)或逆断型向正断型的转换,表明近场地应力受交汇构造影响;实测最大水平主应力方向随孔深增加由NW向转为NWW向,与活动断裂运动力学特性、交汇断裂的左旋运动机制以及震源机制解基本一致;通城河活动断裂近场应力积累水平较低,尚未到失稳滑动水平,地壳是相对稳定的。研究结果为引江补汉工程穿通城河活动断裂工程区稳定性评价提供基础地质力学资料,为跨活动断裂的工程设计提供参考依据。
The Yangtze-to-Hanjiang River Diversion Project is the first large-scale project under construction subsequent to the South-to-North Water Diversion Project.Its diversion tunnel intersects the active creep Tongcheng River fault.Understanding the in-situ stress characteristics of the active fault is crucial for evaluating the project’s stability.The in-situ stress near the complex Tongcheng River active fault was measured,and the fault stability was analyzed to reveal the current geostress state and the critical conditions for fault slip instability.In-situ hydrofracturing tests were conducted in two nearly 1,000-meter-deep boreholes in the vicinity of the Tongcheng River active fault.The results indicate that the current stress state within the measurement depth is divided into two types.Specifically,the spatial principal stress state is hypothesized to transition from a composite(reverse and strike-slip)or reverse type to a normal type at approximately 900±20 meters depth.This suggests that the in-situ stress in the near field is influenced by intersecting faults.The direction of the maximum horizontal principal stress shifts from NW to NWW with increasing borehole depth,which aligns with the dynamic characteristics of active fault movement,the left-slip mechanism of intersecting faults,and the focal mechanism solutions.Finally,based on the measurement data and in line with the Mohr-Coulomb friction sliding criteria and Byerlee’s law,the stability of the active faults was analyzed.Findings reveal that the overall stress accumulation near the Tongcheng River active fault is relatively low and has not reached levels that would induce instability,suggesting that the crust remains relatively stable.These findings provide essential geological and mechanical data for assessing the stability of the Yangtze-to-Hanjiang River Diversion Project near the Tongcheng River active fault zone and offer valuable insights for engineering design across active faults.
作者
周春华
董志宏
邓争荣
付平
艾凯
耿军民
罗笙
ZHOU Chun-hua;DONG Zhi-hong;DENG Zheng-rong;FU Ping;AI Kai;GENG Jun-min;LUO Sheng(Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan 430010,China;Changjiang Geotechnical EngineeringCO.,Ltd.,Wuhan 430010,China)
出处
《长江科学院院报》
CSCD
北大核心
2024年第10期110-118,共9页
Journal of Changjiang River Scientific Research Institute
基金
云南省重大科技专项计划项目(202002AF080003,202102AF080001)
中央级公益性科研院所基本科研业务费项目(CKSF2023316/YT,CKSF2023308/YT)。
关键词
活动断裂
深孔地应力
Byerlee定律
断裂稳定性
引江补汉工程
active fault
in-situ stress of deep borehole
the law of Byerlee
fault’s stability
River Diversion Project from the Yangtze River to the Hanjiang River
