碎裂结构岩体动态剪切特性及强震溃散机理研究

The structure of the cataclastic rock mass is very broken, and its strength is very low, the most significant feature of which is that it contains a large number of weak, filled discontinuities. The rock slopes often behave as collapsing and sliding failure of the shallow cataclastic rock mass under the strong earthquake. However, up to now, scientists are still not clear about the dynamic process of the seismic-induced shallow failure of the slope. The dynamic shear characteristics of the cataclastic rock mass and the collpasing mechanism induced by the strong earthquake within the seismic strain rate range are the keys to understanding the shallow co-seismic landslide dynamics and the hazard inducing model. However, there is little research on this issue, so it needs to be further studied. Based on previous research of the applicants, additional surveys and accurate measurements of typical cataclastic rocks will be conducted in the quake-affected areas to establish 3D models of typical cataclastic rock masses through 3D modeling of discrete fracture network. Additionally, laboratory experiments and physical model tests will be carried out to study the dynamic shear characteristics of weak, filled discontinuities under seismic strain rate and then to put forward their deformation constitutive models and strength criteria. Meanwhile, the dynamic deformation and failure progress of common cataclastic rock masses under seismic strain rate will be investigated, and its progressive failure process and strength characteristics will also be quantitatively characterized. Eventually, the numerical model for the dynamic response of cataclastic rock masses under strong earthquakes will be developed based on discrete element method and to study the collpasing mechanism of typical cataclastic rock through fine numerical simulations, which would provide a scientific basis for disaster prevention and reduction of shallow seismic landslides induced by strong earthquakes.

碎裂岩体的结构十分松散破碎，强度较低，其最显著的特征是含有大量软弱充填结构面。强震作用下斜坡多发生浅层碎裂结构岩体崩滑失稳，目前科学界对其动力过程和孕灾机理还知之甚浅。地震应变率范围内碎裂结构岩体的动态剪切特性和强震溃散机理是认识浅层地震滑坡动力过程及孕灾机理的关键，前人对该问题的研究十分欠缺，亟待深入。以前期研究为基础，补充调查并精细测量地震灾区典型碎裂结构岩体，通过三维结构面网络模拟建立出典型碎裂结构岩体的三维结构模型；开展地震应变率下的室内动力学试验和物理模型试验，研究软弱充填结构面的动态剪切特性并构建其动力变形本构和强度模型，研究典型碎裂结构岩体的动态剪切变形、破坏规律，定量刻画其渐进破坏过程和强度特征；开发碎裂结构岩体强震动力响应离散元数值分析程序模块，通过精细数值模拟，研究典型碎裂结构岩体的强震溃散机理，为强震诱发浅层地震滑坡灾害的防灾、减灾提供科学依据。

碎裂岩体的结构十分松散破碎，强度较低，其最显著的特征是含有大量软弱充填结构面。强震作用下斜坡多发生浅层碎裂结构岩体崩滑失稳，目前科学界对其动力过程和孕灾机理还知之甚浅。地震应变率范围内碎裂结构岩体的动态剪切特性和强震溃散机理是认识浅层地震滑坡动力过程及孕灾机理的关键，前人对该问题的研究十分欠缺，亟待深入。本项目通过野外科考、技术研发、理论研究、室内试验、数值模拟等手段，对碎裂结构岩体动态剪切特性及强震溃散机理研究开展了深入系统的研究：研发了碎裂岩体结构面动力测试技术，包括用于测试粗糙结构面循环剪切特性的剪切盒、适用于软弱结构面动态剪切特性测试剪切盒以及不同含水率和排水工况软弱结构面动态压缩特性的套筒装置；研究了碎裂岩体贯通结构面形貌刻画及动态剪切力学特性，建立了结构面动态强度准则；建立了基于颗粒离散元的岩体动力渐进破坏分析模型，研究了碎裂岩体中埋藏型结构面震裂损伤破坏规律；研究了地震应变率加载下典型碎裂结构岩体的剪切力学特性，揭示了微裂纹起裂-扩展-贯通-宏观破坏的渐进破坏模式和机制；建立了应力波在典型层状岩体中传播理论预测模型，分析了岩体结构特征和地下水对层状碎裂岩体动力响应的影响作用；建立了不同风化程度碎裂岩体中岩石材料微观-宏观力学行为预测模型，揭示了动力作用下结晶岩微观结构异质性对其拉伸强度的影响作用；建立了强震应力波与结构面互馈作用离散元数值模型，开展了数值模拟研究揭示了典型碎裂结构岩体的强震溃散机理。研究成果不仅丰富了岩体工程地质力学理论，具有重要的科学意义，而且在高地震烈度区重大交通、水电等工程规划、设计、建设及地质灾害防灾减灾方面具有良好的应用前景。