大变形锚杆支护效应分析

根据大变形锚杆的力学和变形特性,建立大变形锚杆–围岩相互作用结构模型,研究锚杆加固圆形隧道时的支护效应,并通过数值模拟验证了模型和求解方法的有效性。采用上述求解方法,定量分析了原岩应力、岩体强度以及大变形锚杆安装密度、长度和安装时间对其支护效果的影响规律。结果表明,在高应力或极软岩等恶劣地质条件下,围岩产生较大位移的情况下,大变形锚杆可以更好的发挥支护效应。大变形锚杆加固的主要作用在于限制塑性区围岩的变形,对塑性区边界的位置以及弹性区岩体变形的控制效果不明显。还通过改变安装锚杆时等效内支撑力的大小,揭示了锚杆安装时间对其支护效应的影响规律。研究结果可为大变形锚杆支护设计及参数优化提供基础理论依据。

Reinforcement effect of yielding bolts

According to the mechanical behaviors and deformation characteristics of yielding bolts, a coupling model is proposed to account for the interaction between the bolt and the rock mass. An analytical solution for the coupling model applied in a circular tunnel is achieved. The reinforcement mechanism of the yielding bolts is demonstrated through an illustrative case study and verified by numerical simulations. Based on the proposed model, the influences of different parameters, including stress condition of rock mass, strength of rock mass, density of bolts, length and installing time of bolts the, on reinforcement effect are estimated quantitatively. The parameter studies show that the performance of the yielding bolts is better in the case of large rock deformation. The yielding bolts can reduce the deformation of plastic zone significantly, while the control effect in the elastic zone is not very obvious. The influences of reinforcing time are studied by changing the artificial inner stress when the bolts are installed. The results may provide a necessary theoretical basis for the design and parameter optimization of yielding bolts.