Sleeve-Swell Yielding Bolt And The Support Characteristics Study

With the introduction of the national“One Belt,One Road”strategy,the mining depth of the coal mining industry is also increasing,nonlinear large deformation would be prominent under the complicated environment of three“high”one“disturbance”.This would cause large roadway deformation,long deformation time,seriously destroyed surrounding rock and increasing failed supporting,which will make the roadway maintenance difficult.It is not so obvious to prevent large deformation when using the current roadway supporting.The supporting material cannot provide constant supporting resistance to controllably release deformation energy inside the rock mass.Therefore,it cannot be reached for the roadway stability control goal of supporting-surrounding rock interaction,neither meet constant resistance requirement under different surrounding rock environment in terms of deep surrounding rock with nonlinear deformation and long deformation time features.This paper introduce a new hierarchical constant resistance large deformation anchorage structure that can solve the large deformation problem during deep soft rock roadway reinforcement.The anchorage structure performances are studied by laboratory test,theory analysis and numerical simulation.The main conclusions are as follows:?1?According to the existing problems in the mining of deep soft rock roadway,a sleeve-swell yielding bolt is developed to adapt to the nonlinear large deformation of the anchored rock mass.The structural characteristics and working principle of the yielding bolt are introduced.The thesis details the specific functions of each structural component,calculates the specific dimensions of each structural component and checks the connection strength of each structural component,indicating that the connection between the various components is theoretically stable and the outer sleeve Sheath protection for the yielding bolt in actual support.?2?The thickness of the plum tube,the inclination angle of the plume and the height of the column were determined as the three factors affecting the support resistance of the a sleeve-swell yielding bolt through the orthogonal design,and the static tensile test of three factors and four levels was carried out to test and verify the mechanical properties of the graded constant resistance under the action of tension and determined the constant resistance value and the deformation amount of each level.The influence of the plume tube thickness,the weeping angle and the height of the column on the support resistance is ranked from high to low by the range analysis and the best combination is obtained.According to the order of the bolt support resistance under various factors,the empirical formula of the sleeve-swell yielding bolt support resistance is:y=0.43x₁+0.31x₂+76.9x₃-24.12.The formula has been compared with the experimental data which with sufficient accuracy.?3?The mechanical properties of each group of Yielding Bolts in static tensile test were numerically simulated by ABAQUS software,and the similarity test was carried out by using the cosine function.The results show that the model has high similarity with the actual test and can be used for the stress distribution of each type of sleeve-swell yielding bolts,the damaged area is determined,and the relationship between the average equivalent stress and the axial load under three factors is obtained.?4?Through the theoretical calculation of the radius and critical radius of the yielding bolt,the maximum resistance of the yielding bolt in the constant resistance pressure stage is obtained.The analysis of variation of surrounding rock pressure and the interaction of the bolt during the excavation process of the roadway proves that a reasonable maximum pressure distance can prevent the bolt body from prematurely yielding and destroy the supporting effect.By improving the classic spring slider,a sleeve-swell yielding bolt-surrounding rock coupling model is established and the axial force equation for the yielding bolt in the working phase is obtained.?5?Based on the MIDAS GTS/NX numerical analysis software,the numerical calculation model of the deep soft rock roadway construction stage was established,and the regular pattern of the deformation and destruction of surrounding rock and the bolt axial force of ordinary bolt and sleeve-swell yielding bolt in the roadway support process were obtained.It is finally determined that the sleeve-swell yielding bolt is more suitable for the support of deep soft rock roadway through comparative analysis.The paper has 65 pictures,12tables,and 59 references.