Load Bearing Characteristic And Application Research Of The Bending Extensible Bolt

With the global demand of mineral resources increasing, more mines turn into the deepmining. Effects of deep roadway under high temperature, high pressure and other conditions,rib spalling, caving and the floor heave are becoming more serious. Deep roadway supporthas become pressing issues which major mines at home and abroad have to face. It has beenfound that the bending extensible bolt can provide larger elongation and serve as one of theeffective means to solve the deep roadway support problems. This article discusses theextensible bolt support theory at first, then focus on the analysis of the load-bearingmechanism of the bending extensible bolt and carried on the drawing experiment of bendingextensible bolt in the laboratory. Finally according to the damage of roadway in a mine ofguizhou, using the bending extensible bolt to optimize the support scheme has a goodsupporting effect. The main research results of this article are as follows:Summarizes the extensible bolt support principle and essence, analyzes the bearing andforce of bending extensible bolt on fully anchor, end anchor and double end anchor. Theresults show that, the double end anchor can play a better performance of its structure, tomaintain the stability of surrounding rock.Analyzed the relationship between the bending unit length, curvature and deformation ofthe bending extensible bolt, through the numerical calculation, further analysis of the curvedsection stress concentration rules shows that when the bending unit is short, the curvature islarge, curved section stress concentration obviously, a large amount of elongation provided.Therefore, design the bending structure should consider the bending unit stress andelongation.Detailed the fabrication process of bending bolt with18mm diameter and a tensile testswere performed on this bolt. Comparison the stress and strain relations of key point betweenstraight rod section and bending section, it has been found that the inner diameter bendingsection and the joint of the bending and straight section are the weak link to bearing. At thesame time, the ultimate elongation and ultimate strength of bending extensible bolt willimprove with increasing the loading time.According the obvious situation of the seriously breaking roof, rib spalling and cavingobviously of a mine in Guizhou, combined with the mine geological conditions and theload-bearing mechanism of the bending extensible bolt, then decided to use the bendingextensible bolt optimize the supporting scheme. As a result, when reinforce the roadway dome,spandrel and base angle with the bending extensible bolt, the situation of roadway’s damagehas been changed observably.