高地应力下白鹤滩地下洞室群含错动带岩体破坏模式及机制研究

在建的白鹤滩地下洞室群规模巨大,具有"高边墙、大跨度、高地应力、复杂地质条件"的特点,在高应力开挖卸荷过程中,遭遇到延展性强且力学性质差的多条大型错动带的影响,使得含错动带岩体遭遇到不同程度的变形破坏问题。结合地质、施工、监测、测试及数值分析等资料,首先从错动带产状、成因和自身特点等方面对错动带的工程特性进行详细论述,然后对因错动带导致工程岩体结构变形失效或破坏的实例进行归纳总结,从结构控制因素上将含错动带岩体的破坏模式划分为塑性挤出型拉伸破坏、结构应力型塌方/掉块和剪切滑移型破坏3种类型;其次,研究分析各类含错动带岩体的破坏特征与机制,包括时空演化过程、形态特征、破坏规模等,初步揭示3种破坏模式对应的力学机制;最后,给出典型的含错动带岩体破坏模式分析预测和支护探讨实例,从而为白鹤滩地下厂房施工过程中含错动带岩体不稳定性问题的预测和调控提供借鉴。上述研究成果对于高应力条件下类似的地下洞室群含错动带岩体的稳定性研究具有重要的参考价值和指导意义。

Failure modes and mechanisms for rock masses with staggered zones of Baihetan underground caverns under high geostress

The underground powerhouse caverns at Baihetan under construction are quite huge and have the characteristics of high side wall，large span，high geostress and complicated geological conditions. In the process of excavation unloading under high geostress，the caverns have been affected by several large staggered zones with poor ductility and mechanical properties. As a result，the rock masses with staggered zones have encountered various kinds of deformation and failure problems. On the basis of the collected data from the geological，construction，monitoring，testing and numerical analysis，the engineering properties of staggered zones are described in detail in terms of occurrence，causes and characteristics. The instances of distortion failure or destruction of engineering rock mass structure induced by the staggered zones are summarized. From the point of view of the structure controlling，the failure modes of rock masses with staggered zones are categorized into the plastic squeezing-out tensile failure，the structural stress-induced collapse/block-fall and the contact shear slip failure. The characteristics of three failure modes are studied and analyzed regarding the spatial and temporal development，the morphology，the scale of destruction and so on. The corresponding mechanisms of three kinds of failures are revealed initially. A typical example of structural stress induced collapse is presented to further explain the analysis and prediction of failure mode and supporting measures.