某地下洞室群加锚岩体支护仿真分析研究

Simulation Analysis of Anchored Rock Mass' Supporting in the Underground Caverns Based on MIDAS/GTS

针对某水电站地下洞室群加锚支护情况,研究了加锚区岩体的作用机理及相应的数值模拟方法。采用两组公式对加锚区岩体参数进行了修正,通过加锚区岩体抗剪强度和刚度的提高来模拟砂浆锚杆的锚固效应;通过对围岩施加等效均布压力和布置植入式预应力桁架两种方式,对预应力锚杆进行模拟。对加锚区岩体参数的研究表明,位移对变形模量的敏感性较大,对黏聚力的敏感性相对小一些;锚喷支护对于岩体的加强作用宏观上表现为加锚区岩体的抗剪强度和刚度均有所提高,而对于刚度的加强效应更为明显。根据围岩应力、塑性区分布情况,采用布置植入式预应力桁架方式进行模拟可以有效减小围岩的压应力集中现象,使压应力、塑性区分布更加合理。

The Mechanism and related numerical simulation methods of the rock and anchor bolt were studied according to the supporting of a hydropower station＇s underground caverns＇s anchorage zone.Two formulas were used to revise the parameters of the rock combining anchor bolt.The anchoring effect of bolt was simulated by increasing the shear strength and rigidity of the rock combing anchor bolt.The two methods,applying equivalent uniform pressure to the surrounding rock and arranging implantable prestressed truss were used respectively to express the effect of the prestressed anchor.According to the study of parameters of the rock combining anchor bolt,the change of displacement was more sensitive to the change of deformation mold but less sensitive to the cohesion;the broadly strengthened effect of the shotcreting support played on the rock was the increase of the shear strength and rigidity of the rock and anchor bolt,and the increase of the rigidity was more obvious.On the grounds of the distribution of the surrounding rock stress and plastic zone,arranging implantable prestressed truss could efficiently decrease the concentration of the surrounding rock stress and rationalize the distribution of the stress and plastic zone.