应力、渗流、温度及损伤耦合作用下裂隙岩体破裂机理及广义粒子动力学（GPD）模拟分析

发布时间：2018-04-02 04:02

本文选题：裂隙岩体　切入点：裂隙扩展　出处：《重庆大学》2016年博士论文

【摘要】：本文提出一种新的数值模拟计算方法-广义粒子动力学(GPD)算法对地下裂隙岩体在应力、渗流及温度耦合作用下裂隙扩展机理进行理论及数值研究。(1)采用Hoek-Brown强度准则对脆性岩体的裂隙启裂、扩展和连接进行判断。当粒子的应力满足Hoek-Brown强度准则时,粒子失效,根据失效粒子的破裂顺序对裂隙扩展路径进行描述。(2)采用GPD数值方法,建立岩体系统的应力、渗流、损伤耦合模型。模拟研究了含水及不含水情况下,地下隧道开挖卸荷后的裂隙扩展规律,以及隧道围岩的位移情况;研究了渗流场对应力场及损伤场的影响。(3)本文提出一种新的“生成粒子算法”,来模拟竖向荷载和裂隙水压耦合作用下岩体裂隙扩展机理。当张开裂纹的张开度达到一定程度时,携带水粒子参数的新粒子会在空白区域生成;根据Hoek-Brown强度准则对岩石粒子间虚拟键的断裂进行判断;断裂虚拟键只能够承受粒子间的压应力作用,而不能承受拉应力作用;裂隙水压对翼型裂纹起裂角及起裂位置有很大影响,随着裂隙水压的增大,翼型裂纹的扩展方向与预置裂纹轴线的夹角逐渐增大,起裂位置逐渐向预置裂纹轴线方向移动。(4)采用GPD数值方法,建立岩体的应力、温度、损伤耦合模型。在基质热膨胀系数小于内嵌材料的热膨胀系数时,内嵌颗粒处于静水压力状态,基质材料在径向方向受压,环向方向受拉,由于岩石材料抗拉强度较低,在环向拉力作用下会产生径向裂纹;在基质热膨胀系数大于内嵌材料的热膨胀系数时,内嵌颗粒处于拉伸状态,基质材料则在径向方向受拉,环向方向受压,此时最大拉应力位于内嵌材料和基质材料的接触面位置,即在接触面位置,基质材料发生拉伸破坏。(5)在GPD数值方法中,建立岩体的温度、渗流耦合计算模型。考虑温度场影响时,一方面,洞室开挖后周边围岩温度降低,导致岩体渗透系数降低;另一方面,温差的存在对渗流扩散产生影响,导致洞室周边裂隙水的渗流速度明显比不考虑温度场时偏低,渗流迹线在相同渗流时间段内扩展长度减小。在渗流作用条件下,由于宏观裂隙渗流的影响,造成在裂隙处温度场分布不均,温度降低较慢,同时由于渗流的影响,随着计算步加大,温度场向外扩展,温度场在含宏观裂隙的位置出现温度传播受阻的情况。这表明,不仅温度对渗流场有较大影响,渗流场对温度场也有较大影响。(6)在应力、渗流、温度、损伤耦合情况下,不同侧压力系数对洞室周围岩体损伤区的扩展有较大影响。当侧压力系数较小时,洞室拱顶上方及底板下方损伤区扩展范围较大,宏观裂隙开裂水平也较高;随着侧压力系数的增大,洞室周边拉应力区逐渐减小,宏观裂隙的开裂水平也逐渐减小;但在开挖卸荷初始阶段,围岩损伤区却较侧压力系数较小时要大。
[Abstract]:In this paper, a new numerical simulation method, Generalized Particle Dynamics (GPD) algorithm, is proposed for stress analysis of underground fractured rock mass. Theoretical and numerical study on fracture propagation mechanism under coupling of seepage and temperature. (1) Hoek-Brown strength criterion is used to judge fracture initiation, expansion and connection of brittle rock mass. When the stress of particles meets the Hoek-Brown strength criterion, particle failure occurs. According to the fracture sequence of failure particles, the fracture propagation path is described. (2) using GPD numerical method, the coupling model of stress, seepage and damage of rock mass system is established. The law of crack expansion after excavation and unloading of underground tunnel and the displacement of surrounding rock of tunnel; In this paper, a new "particle generation algorithm" is proposed to simulate the crack propagation mechanism of rock mass under the coupling of vertical load and fissure water pressure. The new particles with water particle parameters will be formed in the blank area; according to the Hoek-Brown strength criterion, the fracture of the virtual bond between rock particles can be judged. The fracture virtual bond can only withstand the compressive stress between the particles, but not the tensile stress. The crack water pressure has a great influence on the crack initiation angle and position of the airfoil crack. With the increase of the crack water pressure, the crack propagation direction and the angle between the prefabricated crack axis and the crack propagation direction gradually increase. The stress, temperature and damage coupling model of rock mass is established by GPD numerical method. When the thermal expansion coefficient of matrix is less than the thermal expansion coefficient of embedded material, The embedded particles are under hydrostatic pressure, the matrix material is compressed in the radial direction and the tensile direction is in the circumferential direction. Because of the low tensile strength of the rock material, the radial crack will occur under the action of the toroidal tensile force. When the thermal expansion coefficient of the matrix is larger than the coefficient of thermal expansion of the embedded material, the embedded particles are in the tensile state, while the matrix material is pulled in the radial direction and compressed in the circumferential direction. In this case, the maximum tensile stress is located at the interface position of the embedded material and the matrix material, that is, the tensile failure of the matrix material occurs at the contact plane position. In the GPD numerical method, the temperature of the rock mass is established. Considering the influence of temperature field, on the one hand, the temperature of surrounding rock decreases after excavation, which leads to the decrease of permeability coefficient of rock mass; on the other hand, the existence of temperature difference has an effect on seepage diffusion. As a result, the seepage velocity of fissure water around the cavern is obviously lower than that when temperature field is not taken into account, and the length of seepage trace is decreased in the same seepage period. Under the condition of seepage, because of the influence of macroscopic fissure seepage, As a result of the uneven distribution of temperature field in the fracture, the decrease of temperature is slow. At the same time, due to the influence of seepage, with the increase of calculation step, the temperature field expands outwards, and the temperature field appears to be blocked in the position of macroscopic fissure. Not only does temperature have a great effect on the seepage field, but also the seepage field has a great effect on the temperature field.) in the case of stress, seepage, temperature and damage coupling, Different lateral pressure coefficients have great influence on the expansion of rock mass damage zone around the cavern. When the lateral pressure coefficient is small, the damage area above the arch roof and the bottom plate of the cavern is larger, and the macroscopic crack cracking level is also higher. With the increase of lateral pressure coefficient, the tensile stress zone around the cavern decreases gradually, and the crack level of macroscopic crack decreases gradually, but in the initial stage of excavation and unloading, the damage zone of surrounding rock is larger than the lateral pressure coefficient.
【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU45

【参考文献】