Study On Surrounding Rock Stability Of Roadway Under Fast Mining

Coal energy will still play a leading role in energy structure of China in the foreseeable future. With the research and broad application of large mining height technology and super long coal face, not only the output can improved, but also the roadway drivage ratio and maintenance quantity can reduced. In recent years,with the practice of coal face of high-output and high-efficiency under the fast mining, it is noted that the deformation and the strength of underground works are affected by the time factor.Therefore, the study on surrounding rock deformation characteristics under the influence of mining can help to correctly understand the movement rule of roof terrane under fully-mechanized mining, further study the laws between the deformation of roadway and mining speed, promote safety production and reducing producti-on costs. The work involves:(1)This paper makes a comprehensive introduction to the research directions,contents and influencing factors about rheological mechanical theory,summarizes the major research directions which include creep, stress relaxation, long-term strength, elastic after effect and hysteresis effect, etc. The creep, relaxation about combined models which incloude Kelvin model, Maxwell model,Poynting-Thomson model,Burger model,viscous-plastic model, viscous-elastic-plastic model are given.(2)Through to analyze the rheological properties and aging characteristics of surrounding rocks,the main influencing factors are obtained which influence rheological deformation of roadway:viscous properties of the rock material itself, stress levels and loading conditions to the rock, the temperature and humidity, the occurrence environmen of the rock and so on. The deformation of mining roadway which caused by the mining is produced mainly by the abutment pressure. The influence to the stress field of surrounding rock which is caused by mining speed is mainly embodied in:the integrity degree of transfer process about surrounding rock stress under different mining speed; the changes of cutting depth unit time are caused by different mining speeds,which affected unloading and loading process and changes in loading rate about the surrounding rock; mining speed differences have a certain impact to the creep time on the rock, which affects the deformation and stress distribution.(3) According to analyze the rheological properties of roadway about the Shangwan Coal Mine 51101 Face, deformation formula which is effected by the vertical stress is derived by using the Burgers rheological model of four-ele- ments.(4) The surrounding rock deformation - time curves in different extraction rates are obtained by using Burgers creep viscoplastic model which provided by FLAC3D. Through to analyze the results of numerical simulation,conclusions are obtained: the faster mining speed, the smaller deformation rock;the deformation of surrounding rock is mainly caused by the creep outside Support pressure of the face;when the roadway is began to affecte by the support pressure of the face, deformation is caused by the support pressure of the face ;under the same condition, the slower mining speed, the greater deformation of surrounding rock which creeps longer.(5) By contrast with displacement - time curves on51101 face of Shangwan Coal Mine, the figures of numerical simulation can truly reflect the condition of simulated objects.