锚杆松弛与岩体蠕变耦合预应力损失模型研究

为研究预应力锚杆作用下节理岩体的变形破坏,通过引入描述锚杆弹塑性变形的普兰特体对原有广义开尔文模型进行修正,建立起描述外荷载作用下锚杆预应力损失与围岩变形破坏的耦合模型。研究表明:(1)锚杆预应力损失分为两个阶段,且第一阶段预应力损失占总体预应力损失的比重达到92%以上;(2)通过定义松弛时间并绘制松弛曲线,利用岩石蠕变屈服强度进行分段处理,选择与室内试验最为接近的松弛曲线,从理论上说明预应力损失分段的合理性;(3)结合室内试验数据,对耦合模型进行参数识别,并通过拟合系数R²的值非常高说明该耦合模型的准确性。通过考虑锚杆的弹塑性变形,可以更好地反映围岩的变形,有利于围岩的后期支护与安全。

Study on the Model of Prestress Loss Coupled with Cable Relaxation and Rock Creep

In order to study the deformation and failure of jointed rock mass with anchor under the action of prestressed anchor, the original generalized Kelvin model is modified by introducing the Prandtl body, which describes the elastic-plastic deformation of anchor. The coupling model between the prestress loss of anchor and the deformation and failure of surrounding rock under the action of external load is established. The results show that: (1) the prestress loss of the anchor bolt is divided into two stages, and the prestress loss in the first stage accounts for more than 92% of the total prestress loss; (2) By defining the relaxation time and drawing, the relaxation curve is divided by creep yield strength of rock, and the relaxation curve closest to the indoor test is selected to explain the rationality of prestress loss in theory; (3) Combining with the indoor test data, the parameters of the coupling model are identified, and the accuracy of the coupling model is illustrated by the value of fitting coefficient R. By considering the elastic-plastic deformation of bolt, the deformation of surrounding rock can be better reflected, which is conducive to the later support and safety of surrounding rock.