多界面复合锚杆荷载传递机制的数值模拟

Numerical Simulation on Load Transfer Mechanism of Multiinterface Composite Rockbolt

摘要:

采用Abaqus对复合锚杆拉拔试验进行模拟,针对复合锚杆的破坏形式多为界面破坏,应用改进的Cohesive单元对复合锚杆4种界面材料进行模拟,并建立轴对称弹塑性有限元模型对复合锚杆的拉拔试验进行分析.研究成果主要包括:①钢绞线轴向应力及界面剪应力均服从指数分布,且随着荷载的增大,锚杆近端的握裹力被克服,剪应力峰值向后转移.②南竹复合材料、南竹水泥砂浆界面剪应力峰值随着主控面剪应力峰值的转移而转移.③南竹管材受周围刚度较大的复合材料及水泥砂浆的约束,其轴向应力峰值分布在南竹的中部.④水泥砂浆土体界面因边界条件不同于其他界面,其剪应力沿锚杆轴向从近端至远端不断增大.数值模拟结果与现场试验测量结果符合较好,验证了该数值方法的有效性.

Abstract:

Based on the Abaqus program,a pullout test of the composite rockbolt was simulated.Considering the main failure mode of the rockbolt,i.e.interface failure,an improved cohesive element was employed to simulate the four interface materials,and an axisymmetric elastoplastical finite element model was built to analyze the pullout test.It is concluded that the axial stress and the shear stress distribute along the steel strand exponentially.The bond strength will be overcome with the increase of the load,and the peak of shear stress will move to the far end of the bolt.The peak shear stress along the bamboocomposite material interface and the bamboomortar interface will move accordingly with that of the master interface.Under the constraint of the composite material and cement mortar with higher stiffness,the peak axial stress is located on the middle of the bamboo.The shear stress along the mortarsoil interface increases from the near end to the far end due to the different boundary condition.A comparative study shows the numerical simulation agrees well with the measured data,so the numerical method is certificated to be effective.