锚杆与锚索协同锚固的能量分析研究

Energy analysis of synergetic anchorage with bolt and anchoring cable

地下工程围岩的变形、破坏及失稳过程中始终伴随着能量的转化和转移,支护体对围岩体的变形失稳具有一定的控制作用,对锚固体和围岩内能量的转化和转移也有影响。本文以Mohr-Coulomb准则为依据,从能量角度分析了圆形巷道开挖后围岩内弹性应变能和塑性应变能在围岩中的分布情况和影响因素。指出在破碎区围岩的力学参数中,粘聚力相比内摩擦角对围岩能量分布影响较大。注浆和提高锚杆预应力可以增大岩体的粘聚力,粘聚力的增加可以减少破碎区范围,但会加剧塑性能的集聚,需要配以组合锚索为锚固体提供均布支护力,减弱围岩塑性能集聚效应。为保证锚杆与锚索协同工作,其预应力必须相互匹配,且锚杆和锚索的预应力应与锚杆的弹性模量相匹配,在减少破碎区范围的同时,减弱塑性破坏能集聚程度,降低围岩弹性能,使围岩处于少破碎、均匀破碎和低能量的稳定状态。

The deformation,failure and instability of surrounding rock in underground engineering are always accompanied by the transformation and transfer of energy.The application of support body has a certain control effect on the deformation and instability of surrounding rock,and it must also affect the transformation and transfer of energy in anchorage body and surrounding rock.Based on Mohr-Coulomb criterion,the distribution and influence factors of elastic strain energy and plastic strain energy in surrounding rock after excavation of circular roadway was analyzed.It was pointed out that among the mechanical parameters of surrounding rock in fractured zone,cohesion had greater influence on energy distribution than internal friction angle.Grouting and improving the prestress of bolt could increase the cohesion of rock mass.The increase of cohesion could reduce the range of broken zone,but it would aggravate the agglomeration of plastic energy.It was necessary to provide uniform supporting force for anchor body with combined anchor cable to weaken the agglomeration effect of plastic energy of surrounding rock.In order to ensure that the anchor rod and the anchor cable worked together,the prestress must be matched with each other,and the prestress of the anchor rod and the anchor cable should be matched with the elastic modulus of the anchor rod.While reducing the scope of the crushing zone,the degree of agglomeration of plastic failure energy was weakened,the elastic energy of surrounding rock was reduced,and the surrounding rock was in a stable state of less crushing,uniform crushing and low energy.