叶巴滩水电站坝区右岸深部变形破裂成因模拟研究

发布时间：2019-04-09 07:36

【摘要】：自上世纪八十年代,深部变形破裂在水电站坝址区揭示以来,其成因机理一直受到工程界和学术界广泛关注,目前这一问题尚无统一定论。揭示深部变形破裂的成因机制对水电站工程勘察、设计、施工和运营有重要的现实意义和理论价值。本文以叶巴滩右岸典型的深部变形破裂为研究对象,在野外详查资料的基础上,结合室内试验结果,利用地震波CT技术,揭示硐间岩体的深部变形破裂发育分布规律和变形破坏特征;根据岩体内深部变形破裂的特征,建立地质力学模型开展物理模拟试验,分析加-卸荷条件下,应力集中区与断层对应关系;利用3DEC离散元软件,建立三维模型进行数值模拟仿真试验,分析了多次加载~卸载过程中,受平行结构面切割的岩体内应力集中-扩散规律。通过将上述试验与现场深部变形破裂的对比,进一步讨论断层控制型深部变形破裂的成因机制。本文主要的研究成果如下:(1)深部变形破裂的分布规律。坝区右岸深部变形破裂集中发育于高高程区域,随高程的降低,深部变形破裂数量快速减少。深部变形破裂发育的水平深度为硐口以里80m-150m,破裂带宽度一般为4m~55m。深部变形破裂在同一水平高程贯通性好,延伸较宽,在垂直方向上贯通性差。(2)坝区右岸深部变形破裂主要表现出受断层控制。深部变形破裂的优势方向为NW向,对深部变形起控制作用的断层共14条,其优势方向为NWW向和NE向。右岸结构面表现出“X”共轭体系,因此右岸深部变形破裂是在构造主应力方向为N60°~80°E的应力场环境中,受断层影响,在断层围限区域中形成,属于断层控制型深部变形破裂。(3)岸坡岩体在卸荷状态下,积聚的残余应变能快速释放,在断层交切、发育平行断层的岩体中形成大量拉应力集中区。其规律在于:拉应力集中区主要分布平行断层之间,且一般最大值出现在断层端部,在多条断层交汇区域应力集中情况明显增强,同时拉应力集中区往往呈带状发育。上述发育分布规律与深部变形破裂在空间的分布规律一致。(4)深部变形破裂形成过程从应力聚散角度可划分为两个阶段,应变能积聚阶段和应变能集中释放阶段。深部变形破裂发育区域表现出强烈的能量聚集~释放迹象,随岩体卸荷,岩体在中局部压应力逐渐减小,甚至变成局部拉应力,在此过程中,岩体中储存的能量大量释放。(5)叶巴滩水电站坝址区右岸这套深部变形破裂体系是在叶巴滩高边坡高地应力环境中,伴随峡谷形成过程中边坡应力强烈释放,同时叠加叶巴滩特殊的卸荷方式(卸荷方向为最大主应力方向且与岸坡走向垂直)效应,在岩体内两组各自平行、相互交切的NWW向和NE向结构面(小断层)的控制区域内,先期储存的应变能向临空方向强烈释放,产生差异卸荷回弹形成的。
[Abstract]:Since the deep deformation and fracture was revealed in the dam site of hydropower station in the 1980s, the mechanism of its genesis has been paid more and more attention by the engineering and academic circles. At present, there is no unified conclusion on this issue. It is of great practical significance and theoretical value to reveal the mechanism of deep deformation and fracture for engineering investigation, design, construction and operation of hydropower stations. This paper takes the typical deep deformation and fracture of the right bank of Yeba beach as the research object. Based on the detailed investigation data in the field, combined with the indoor test results, the seismic wave CT technique is used. The development and distribution of deep deformation and fracture and the characteristics of deformation and failure of inter-cave rock mass are revealed. According to the characteristics of deep deformation and fracture in rock mass, a geomechanical model is established to carry out physical simulation test, and the corresponding relationship between stress concentration area and fault under loading-unloading condition is analyzed. By using the 3DEC discrete element software, a three-dimensional model is established to simulate the stress concentration-diffusion law in rock mass cut by parallel structural plane during multiple loading-unloading process, and the stress concentration-diffusion law in the rock mass is analyzed in the process of multiple loading and unloading. By comparing the above tests with the in-situ deep deformation and fracture, the mechanism of fault-controlled deep deformation and fracture is further discussed. The main results of this paper are as follows: (1) the distribution of deep deformation and fracture. The deep deformation and fracture of the right bank of the dam area is concentrated in the area of high elevation. With the decrease of elevation, the number of deep deformation and fracture decreases rapidly. The horizontal depth of deep deformation and fracture is 80m ~ (m) ~ (150) m, and the width of fracture zone is usually 4m ~ (55) m ~ (- 1). The deep deformation and fracture have good penetration at the same horizontal elevation, wide extension and poor penetration in the vertical direction. (2) the deep deformation and fracture on the right bank of the dam area are mainly controlled by faults. The dominant direction of deep deformation and fracture is NW, and there are 14 faults which control deep deformation. The dominant direction is NWW and NE. The structure plane of the right bank shows the "X" conjugate system, so the deep deformation and fracture of the right bank is formed in the stress field with the principal stress direction of N60 掳~ 80 掳E, which is affected by the fault and formed in the fault confining region. It belongs to the fault-controlled deep deformation and fracture. (3) under unloading condition, the accumulated residual strain energy is released rapidly, and a large number of tensile stress concentration areas are formed in the rock mass where the faults are intersected and parallel faults are developed. The rule is that the tensile stress concentration area is mainly distributed between parallel faults, and the maximum value appears at the end of the fault, the stress concentration is obviously enhanced in the intersection region of several faults, and the tensile stress concentration area is usually developed in banding. (4) the forming process of deep deformation and fracture can be divided into two stages from the angle of stress divergence, the accumulation stage of strain energy and the stage of concentrated release of strain energy. The deep deformation and fracture area shows strong signs of energy accumulation and release. With the unloading of rock mass, the mid-local compressive stress of rock mass decreases gradually, even becomes local tensile stress, and during this process, the stress of rock mass decreases gradually and even becomes local tensile stress. The energy stored in the rock mass is released greatly. (5) the deep deformation and fracture system on the right bank of the dam site of Yebatan Hydropower Station is strongly released in the environment of high in-situ stress of the Yebatan high slope, accompanied by the formation of the canyon. At the same time, the special unloading mode of Yeba beach (the unloading direction is the direction of maximum principal stress and perpendicular to the bank slope direction) is controlled by two groups of structures (small faults) parallel to each other and intersecting with each other in the NWW direction and the NE direction in the rock mass. The strain energy stored in advance is strongly released to the near-air direction, resulting in the formation of differential unloading springback.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV221.2

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