高应力条件下层状岩体力学特性及时效破裂机制研究

发布时间：2018-08-24 12:44

【摘要】：层状岩体的力学特性及时效破裂演化规律是岩石力学领域重要的研究课题之一。大量实例表明,层状岩体工程的失稳与破坏很多都存在着滞后性,特别是在高地应力环境中开挖卸荷,需要很长一段时间调整岩体应力从而达到新的平衡,有时甚至会发生时滞性岩爆和时效大变形,严重危害工程的施工安全与长期稳定。因此,层状岩体在高应力条件下的力学特性和时效细观破裂演化规律需要进行更深入的认识和研究。鉴于此,本文在丹巴石英云母片岩真三轴试验的基础上,借助三维颗粒离散元理论,引入SJ模型、PSC模型和超级单元clump技术,构建了符合层状岩体的细观力学模型,对不同结构面及不同应力状态和应力路径下层状岩体的力学特性和时效破裂进行了研究。本文的主要研究工作如下:1.以指数型细观内应力驱动的损伤速率和三维颗粒离散元为基础,结合能够描述细观层面时效破裂的PSC模型和描述节理效应的SJ模型,提出了能够模拟层状岩体时效破裂效应的细观力学计算方法,用于模拟岩体的瞬态和时效破裂的结构面效应。同时,结合三维颗粒离散元和地震矩张量理论,给出了模拟岩体瞬态和时效破裂的AE计算方法及空间定位方法。2.基于三维颗粒流理论,通过引入SJ模型、PSC模型和超级单元clump技术,并依据丹巴水电站石英云母片岩的SEM矿物成份检测结果,建立了基于矿物形颗粒状的层状岩体细观结构模型,根据真三轴瞬态压缩试验和流变试验结果以及岩石细观力学参数识别方法,确定了石英云母片岩的瞬态和时效细观力学参数,构建了层状岩体的时效细观力学数值模型。3.基于层状岩体时效细观力学数值模型,对不同节理倾角条件下岩石进行了真三轴瞬态力学试验,研究了层状岩体瞬态力学特征的结构面效应和AE特征,论述层状岩体变形破裂演化规律及细观演化机理。结果表明:层状岩体的破坏模式随着结构面倾角的变化,由岩石本身控制转变为岩石、结构面共同控制,再转变为由岩石本身控制,其中,在45°~75°之间,岩石的破坏模式主要由结构面控制。4.基于层状岩体时效细观力学数值模型,对不同节理倾角条件下岩石进行了真三轴蠕变数值试验,研究层状岩体时效破裂的结构面效应和AE特征,论述岩石时效破裂演化规律及细观演化机理。结果表明:随着结构面倾角的增加,层状岩体时效变形模式由衰减蠕变转化为稳态-加速蠕变转化界限在结构面倾角45°左右;在衰减蠕变类型中,结构面倾角越小,收敛速率越大,收敛时间越快,随着结构面倾角的增加,收敛时间逐步增加,收敛速率越小;在加速蠕变类型中,层状岩体破坏时间近似呈“U”形,倾角45°左右时,岩体破坏时间较长,随着倾角增加,岩体破坏时间逐步降低,在倾角60°左右时破坏时间最短,随着倾角持续增加,岩体破坏时间逐步增加。
[Abstract]:The mechanical properties and aging fracture evolution of layered rock mass are one of the important research topics in rock mechanics field. A large number of examples show that many of the instability and failure of layered rock mass engineering have hysteresis, especially in the environment of high ground stress excavation unloading, it needs a long time to adjust the rock mass stress to achieve a new balance. Sometimes, delay rockburst and large deformation will occur, seriously endangering the construction safety and long-term stability. Therefore, the mechanical properties of layered rock mass under high stress conditions and the evolution law of aging meso-fracture need to be further understood and studied. In view of this, based on the true triaxial test of Danba quartz mica schist, with the aid of three-dimensional particle discrete element theory, the SJ model and super unit clump technique are introduced to construct a meso-mechanical model for layered rock mass. The mechanical properties and aging fracture of layered rock mass under different structural planes, different stress states and stress paths are studied. The main research work of this paper is as follows: 1. Based on the damage rate driven by the exponential meso-stress and the three-dimensional particle discrete element, the PSC model which can describe the aging rupture of the meso-plane and the SJ model which can describe the joint effect are combined. In this paper, a mesomechanical method which can simulate the aging fracture effect of layered rock mass is presented, which can be used to simulate the transient state of rock mass and the structural plane effect of aging fracture. At the same time, based on the theory of three dimensional particle discrete element and seismic moment Zhang Liang, the AE calculation method and spatial location method for simulating the transient and aging rupture of rock mass are presented. Based on the three-dimensional particle flow theory, by introducing SJ model and super unit clump technology, and based on the results of SEM mineral composition detection of quartz mica schist in Danba Hydropower Station, a meso-structure model of layered rock mass based on mineral granulation is established. According to the results of the true triaxial transient compression test and rheological test and the identification method of the meso-mechanical parameters of rock, the transient and aging meso-mechanical parameters of quartz mica schist are determined, and the numerical model of time-dependent mesomechanics of layered rock mass is constructed. Based on the numerical model of time-dependent mesomechanics of layered rock mass, the true triaxial transient mechanical tests of rocks with different joint dip angles were carried out, and the structural plane effect and AE characteristics of transient mechanical characteristics of layered rock mass were studied. The evolution law of deformation and fracture of layered rock mass and the mechanism of mesoscopic evolution are discussed. The results show that the failure mode of layered rock mass changes from rock itself to rock, and then to rock itself, and then to rock itself with the change of slope angle of structural plane, in which, between 45 掳and 75 掳, the failure mode of layered rock is controlled by rock itself. The failure mode of rock is mainly controlled by structural plane. Based on the aging mesomechanical numerical model of layered rock mass, the true triaxial creep numerical tests of rocks with different joint inclination angles were carried out. The structural plane effect and AE characteristics of aging fracture of layered rock mass were studied. This paper discusses the evolution law of aging fracture of rock and the mechanism of meso-evolution. The results show that with the increase of the dip angle of the structural plane, the aging deformation model of layered rock mass changes from attenuated creep to steady-state accelerated creep transformation at about 45 掳of the structural plane inclination, and the smaller the dip angle of the structural plane is in the type of attenuated creep. The larger the convergence rate is, the faster the convergence time is. With the increase of the inclination angle of the structure plane, the convergence time increases gradually, and the convergence rate is smaller. In the accelerated creep type, the failure time of layered rock mass is approximately "U" shape, and the slope angle is about 45 掳. The time of rock mass failure is longer, with the increase of inclination angle, the time of rock mass failure decreases gradually, and the time of rock mass failure increases gradually with the increase of inclination angle, which is the shortest when the inclination angle is about 60 掳.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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