节理岩体裂纹扩展及锚固机理研究

发布时间：2019-04-10 19:42

【摘要】：节理岩体的失效破坏往往是由于赋存于其中的原生节理在荷载作用下产生新生裂纹,并且逐渐扩展,使岩桥贯通造成的。锚杆已经在岩体边坡和隧道开挖加固中得到了成功的应用,但锚杆锚固段内的具体受力分析仍然没有得到清楚的解决。明确锚固力学传递规律、建立准确的界面应力理论模型以及采用合理的数值计算方法都是进行锚杆锚固研究的关键。利用岩石模拟材料研究了受压岩石裂纹起裂和扩展的力学机制,具体通过在长方体石膏试件中设置中心斜裂纹,观测到单轴压缩荷载作用下裂纹的扩展过程。试验中观察到两种分支裂纹(翼型裂纹和次生裂纹)的产生,并得到了其相应扩展规律。同时利用ABAQUS结合扩展有限元法(XFEM)理论编制单元子程序(UEL),其中假设岩体的线弹性本构关系和最大主应力起裂准则,模拟了翼型裂纹扩展的全过程,其结果与试验结果进行了对比,重点考察了裂纹倾角、厚度和摩擦系数对裂纹扩展的影响,同时也考虑了尺寸效应的影响。从锚固段受力连续性理论出发,采用界面剪应力重分布假设,定义出剪切刚度的软化曲线,并利用ABAQUS软件自带的弹簧模型,对典型拉拔试验进行了数值分析,证明了改变砂浆层的尺寸和强度会对锚杆最大拉拔荷载产生影响。与实际试验结果相比,数值解和实测值有相当的一致性。借助于三维有限元计算,尝试采用ABAQUS中实体单元与cohesive单元相结合的形式模拟了在剪切荷载作用下全长注浆锚杆加固节理岩体中杆体与砂浆、砂浆与岩体的相互作用,并采用接触定义模拟节理面之间的作用,进一步揭示了锚杆对岩体加固的影响效果。
[Abstract]:The failure and failure of jointed rock mass is usually caused by the original joints occurring in the joints which produce new cracks under the action of load and gradually expand so that the rock bridges are connected. The bolt has been successfully applied in rock slope and tunnel excavation and reinforcement, but the concrete stress analysis in the anchor section has not been solved clearly. The key of anchoring research is to make clear the transfer law of Anchorage mechanics, to establish accurate theoretical model of interface stress and to adopt reasonable numerical calculation method. The mechanical mechanism of crack initiation and propagation in compressed rock is studied by means of rock simulation materials. The crack propagation process under uniaxial compression is observed by setting a central oblique crack in a rectangular gypsum specimen. Two kinds of branch cracks (airfoil crack and secondary crack) were observed and their propagation laws were obtained. At the same time, the element subprogram (UEL), is compiled by means of ABAQUS and (XFEM) theory, in which the linear elastic constitutive relation and the maximum principal stress initiation criterion are assumed to simulate the whole process of crack propagation of airfoil. The results are compared with the experimental results, and the effects of crack inclination, thickness and friction coefficient on crack propagation are mainly investigated, and the effects of size effect are also taken into account. Based on the theory of mechanical continuity of Anchorage section, the softening curve of shear stiffness is defined by using the assumption of redistribution of interfacial shear stress, and the typical pull-out test is numerically analyzed by using the spring model with ABAQUS software. It is proved that changing the size and strength of mortar layer will affect the maximum pull-out load of anchor rod. Compared with the experimental results, the numerical solutions are in good agreement with the measured values. With the aid of three-dimensional finite element calculation, the interaction between bar and mortar, mortar and rock mass in jointed rock mass strengthened by full-length grouting bolt under shear load is simulated by means of the combination of solid element and cohesive element in ABAQUS. The contact definition is used to simulate the action between joints, which further reveals the effect of anchor rod on rock mass reinforcement.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU45

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