预应力锚杆锚固段应力分布规律及分析

为揭示预应力锚固机理及优化围岩支护参数,基于前人对锚固力的研究,对锚杆—围岩系统进行理论分析,得出弹性状态下围岩体内剪应力及压应力分布表达式,借助Matlab数值计算软件,计算不同锚固方式、围岩性质、锚杆直径及预紧力下预应力在杆体及围岩中的分布情况。结果表明:不同锚固方式下,预应力分布形式基本相同,作用范围不同,加长锚固方式可增大预应力的作用范围;预应力锚固在软岩中的效果较硬岩好;增加锚杆直径可以改善黏锚力在围岩中的扩散效果;增加预紧力无法改变锚固段预应力扩散范围,但可以提高其应力峰值,同时可提高孔口附近围岩的压应力,对表层围岩应力状态的改善效果较好。

Study on Stress Distribution Law in Anchoring Section of Prestressed Bolt

To reveal the pre-stressed anchor mechanism and optimize the supporting parameters of surrounding rock,the stress of the anchor and surrounding rock system was analyzed in this paper,and the expressions of shear and compressive stress distribution in surrounding rock under the elastic state were obtained.By using MATLAB,the pre-stress distributions in the rod body and surrounding rock under different conditions were calculated,such as different anchoring methods,surrounding rock prop-erties,bolt diameters and pre-tightened forces.The results show that,under different anchoring methods,the distribution forms of pre-stresses are basically the same,but the action spheres are different.The lengthening of bolting method can increase the sphere of pre-stress,and the effect of pre-stressed anchor in the soft rock is better than that in hard rock.The increase of anchor diameter can improve the diffu-sion effect of sticky anchor force in the surrounding rock,while the increase of the pre-tightened force can’t change the pre-stressed diffusion range in anchored section,but can improve its peak stress,and improve the compressive stress of surrounding rock near orifice as well,which has efficient improve-ment effect of stress state on the surface of surrounding rock.