库岸消落带巴东组软硬互层岩体强度渐进劣化机理研究

Progressive strength deterioration mechanism of soft and hard interbedded rock mass of the Badong formation in hydro-fluctuation belt of reservoir bank is a significant issue of geological hazards prevention in the Three Gorges area. Two typical sliding-prone soft and hard interbedded rock masses of the Badong formation are selected as subjects to be investigated. Considering the combined effects of water pressure and dry-wet cycle, as well as the effects of wall rock combination, surface morphology and normal stress, three-dimensional laser scanning and rock/discontinuity mechanical tests are conducted to establish the shear strength degradation model of the discontinuities with different/identical rock types of the Badong formation in hydro-fluctuation belt of reservoir bank, and the strength degradation of rocks in the Badong formation is analyzed. Based on the multi-scale fracture network model, three-dimensional discrete element numerical experiments and similar material model tests of soft and hard interbedded rock mass are carried out considering discontinuity/rock degradation under the combined action of water pressure and dry-wet cycle. The results presented above will be compared and validated by the insitu rock mass shear tests conducted in the large field geo-hazard testing site located in the Badong County to reveal the progressive strength deterioration mechanism of soft and hard interbedded rock masses of the Badong formation in hydro-fluctuation belt of reservoir bank. Furthermore, the strength parameter deterioration equation of the soft and hard interbedded rock masses of the Badong formation in hydro-fluctuation belt of reservoir bank can be established and used to investigate the stability of the typical reservoir slopes with soft and hard interbedded rock of the Badong formation by incorporating insitu monitoring data. The results from this study can provide significant scientific theory basis for scientific determination of strength parameters of rock mass and reasonable evaluation of stability of bank slope in the Badong formation.

库岸消落带巴东组软硬互层岩体强度渐进劣化机理是三峡库区地质灾害防治中亟需解决的关键问题。选取巴东组两类典型“易滑岩组”为研究对象，基于巴东组岩体独特的工程地质特性，考虑水压力与干湿循环共同作用以及壁岩组合、表面形貌和法向应力的影响，开展三维激光扫描和岩石/结构面力学试验，建立库岸消落带巴东组异性/同性结构面剪切强度劣化模型，分析巴东组岩石（结构面壁岩）强度劣化规律。建立岩体多尺度三维结构模型，考虑结构面/岩石劣化，开展岩体三维离散元数值试验及相似材料模型试验，依托巴东地质灾害大型野外试验场岩体现场试验对比验证，研究结构面/岩石劣化导致巴东组软硬互层岩体强度劣化的作用机制，揭示库岸消落带巴东组软硬互层岩体强度渐进劣化机理。在此基础上，建立库岸消落带巴东组软硬互层岩体强度参数衰变方程，结合现场监测，研究巴东组典型软硬互层岸坡稳定性，为科学确定巴东组岩体强度参数、合理评价岸坡稳定性提供理论依据。

库岸消落带巴东组软硬互层岩体强度渐进劣化机理是三峡库区地质灾害防治中的关键问题。项目选取巴东组典型“易滑岩组”为研究对象，以湖北巴东地质灾害国家野外科学观测研究站为研究基地，基于巴东组岩体独特的工程地质特性，在库岸消落带巴东组岩石强度劣化机制、巴东组异性/同性结构面剪切强度劣化模型、巴东组软硬互层岩体强度渐进劣化机理、巴东组软硬互层岩质岸坡稳定性研究等方面取得如下成果：（1）研究了干湿循环、渗流等因素作用下巴东组典型岩石微观结构和宏观物理力学参数的变化规律，揭示了库岸消落带巴东组典型岩石强度劣化机制，建立了库岸消落带巴东组典型岩石强度参数劣化模型；（2）分析了干湿循环作用对巴东组软硬互层岩体中典型异性层面壁岩微细观结构及表面形貌的影响，阐明了异性层面与同性层面强度劣化规律的差异和关联，揭示了干湿循环作用下巴东组典型异性/同性层面的强度劣化机制，建立了巴东组典型异性/同性层面的强度参数渐进劣化模型；（3）研究了软岩/硬岩/层面劣化对巴东组软硬互层岩体强度劣化的贡献度及其与岩层倾角的关系，将岩层倾角全范围划分为软岩控制区、软岩-硬岩-层面共同控制区、层面控制区和硬岩控制区；考虑复杂裂隙条件，阐明了软岩/硬岩/层面/裂隙劣化导致巴东组软硬互层岩体强度劣化的作用机制，分析了复杂裂隙几何参数对软岩/硬岩/层面/裂隙贡献度的影响，揭示了库岸消落带巴东组软硬互层岩体强度渐进劣化机理，建立了库岸消落带巴东组软硬互层岩体强度劣化模型；（4）分析了水库运行条件下巴东组典型软硬互层岸坡岩体劣化致灾规律，提出了软硬互层顺层岩质岸坡动态稳定性研究方法。项目研究成果可为科学确定巴东组岩体强度参数、合理评价库水运行条件下巴东组岩质岸坡长期稳定性提供理论依据，具有推广应用前景。