Mechanical Analysis And Application Of Bolt Pretension Device

Bolt pretightening of application in roadway support in coal mine in our country,it still exists in the practical application of pre-tightening force and supporting demand does not match the problem,seriously restrict the application of bolt support in complex conditions.To solve this problem,this paper from the following two aspects: one is the study of mechanism of the rock bolt pre-tightening force,and to explore pre-tightening force,and the effects of the size of roadway surrounding rock supporting;The second is to select the new pre-tightening device and analyze its feasibility.The main results of this article are as follows:(1)Through the method of numerical simulation,theoretical analysis of the effect on the surrounding rock,obtained certain ideal conditions pre tightening force and the deformation of the surrounding rock,the pretightening force from 0-80 kN change,displacement and broken zone size decreased significantly,the average increased preload 10 kN the force can reduce the displacement of surrounding rock is about 2.3%,to ensure that pre tightening force can effectively improve the stability of surrounding rock,it shows that the pre tightening force matching with the surrounding rock can effectively improve the stability of surrounding rock;(2)Comparative analysis of the advantages and disadvantages of the traditional nut lock bolt and the lock bolt clip type mine,mine clip type lock bolt installation process is simple,and can effectively avoid the axial torsion load,under tensile,shear and bending loads,can effectively reduce the maximum stress value of 34%,37%,53%,improve the rod body stress condition,improve the safety and reliability of the rod body use,give full play to the mechanical performance of the rod;(3)Through laboratory test and numerical simulation of mine bolt clip type lock analysis,determine the anchor ring material for the heat treatment of 40 Cr steel,the clip is made of 20 CrMnTi low carbon steel heat treatment,for 335 22 mm diameter thread steel anchor rod body,the anchor ring taper angle of 7 degrees,the clip angle for 6.8 degrees,the anchor ring length 32 mm,diameter 52 mm for final size;(4)Installation clip type lock bolt in the field test in the test section of roof subsidence is ordinary roadway 58.3%,the convergence between the two sidewalls is ordinary roadway 51.2%,showed that the nut bolt clip type lock bolt is better than the traditional practical application by.The results of this study help to determine the pre stress anchor provides a reference for supporting parameters,which provides a new approach to the topic of how to improve the pre tightening force,it has some positive significance to the development of application of pretension bolt in roadway in coal mines.