普立特大桥隧道式锚碇围岩系统的变形规律及破坏机制

针对普立特大桥普立岸隧道式锚碇围岩系统的变形规律及破坏机制问题,采用有限差分法对其进行三维弹塑性模拟,分析了随着荷载的增加系统的塑性区、位移及应力的发展情况.数值结果表明:1设计缆力时,锚碇-围岩系统的位移均维持在mm级;继续加载,锚碇和周围岩体的位移形成的驼峰逐渐明显;至极限状态时,根据锚碇围岩的位移矢量图可勾勒出围岩的破坏范围,其中锚碇上、下部围岩的破坏范围分别为锚碇后锚面宽度的1.1倍和0.5倍;2系统在设计缆力下具有足够的安全稳定性,加载至8倍缆力时,锚碇的环向和径向的围岩塑性区均达到贯通,加载至极限状态时,锚碇周围岩体的塑性区分布形态呈倒塞体状;3根据监测点的位移变化、锚碇围岩塑性区分布及应力扩展情况得到,系统的破坏由锚碇带动周边部分岩体发生整体拉-剪破坏.

Deformation Law and Failure Mechanism of Anchorage-Surrounding Rock System of Puli Extra-large Bridge

Abstract： The deformation law and failure mechanism of anchorage-surrounding rock system were studied by the 3D elasto-plastic numerical simulation using the finite difference method (FDM). The development of plastic zone, displacement and stress were analyzed with the increasing load. It is shown that at the designed cable force, the displacement of the system is maintained in millimeters. The hump of displacement between the anchorage and surrounding rock become clear under the increasing load. At the limit state, according to the displacement vector graph, the failure area of rock can be sketched, in which the upper lower destruction of surrounding rock are respectively 1.1 times and 0.5 times of the width of the back face of anchorage. The system has enough safety stability under the designed cable force. At aloading of 8 times of the cable force, the hoop and radial plastic zones achieve breakthrough. At the ultimate state, the plastic zones appear to be at an anti plug state. According to the displacement of the monitoring point, the plastic zones of surrounding rock and stress extension, the tensile shear complex failure caused by anchorage in surrounding rock may be in a failure mode.
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