Law And Control Of Rockburst In Coal Pillar Under The Condition Of Special Thick And Hard Coal Seam In Hujiahe Coal Mine

Prevention and control of rockburst in coal mine is a worldwide difficult problem. The rockburst problem has become an increasingly prominent with the increase of mining depth in recent years. In particular the rockburst of coal pillar is more serious. Taking rockburst prevention and control of section coal pillar in hujiahe coal mine 401102 working face as as the research object, This thesis analyses the mechanism of rockburst in coal pillar under the condition of special thick and hard coal seam and studies on seismic characteristics and control technology of rockburst and optimizes the layout of roadway in coal pillar, through the method of theoretical analyses and numerical simulation and field practice.This thesis analyses the structure characteristics of overlying strata and the law of stress distribution in coal pillar under the condition of special thick and hard coal seam and determines the “T” overlying strata spatial structure based on the theory of mining pressure and strata control and mechanics of materials. It determines static force consisting of gravity stress and tectonic stress and bearing stress and determines dynamic force consisting of old roof pressure and overlying strata movement and analyses main manifestation of rockburst in coal pillar under the condition of special thick and hard coal seam and studies, through the principle of rockburst induced by dynamic combined with static loadsAccording to the measured parameters, it establishes FLAC2 D numerical model and simulation analysis the stress and structure characteristics of surrounding rock in coal pillar effected by static and dynamic load superposition. The results show that: because the coal pillar accumulates a lot of elastic strain energy under static loading, it will induce damage if the stress exceeds the utmost carrying ability under the additive effect of dynamic load disturbance; The stress increment gradually increases with the increase of loading intensity, when the load strength of 75 MPa, the stress increment is up to 11.2MPa; At the same time, the dynamic load increases coal rock damage degree of mining space and destroies the whole structure of surrounding coal and rock which induces expansion of plastic damage area and stress transfer and obviously increases of floor displacement.It analyses variation law of vertical stress in coal pillar with the change of coal pillar width combined with the working face layout parameter and coal seam occurrence condition. The results show that: The vertical stress increases with the increase of coal pillar width when the coal pillar width is small; The vertical stress reach the peak when the coal pillar width between 20~25m. After that it assumes the "saddle" shaped distribution. It optimize the design of roadway arrangement method in coal pillar according to the simulation results.This thesis has analysis the variation law of shock energy and frequency and implements the regional joint monitoring of dynamic and static load with the application of bursting strain energy and shock wave CT technology. It divides the rock-burst danger zone of coal pillars during mining period and puts forward the unloading management plan with the large diameter bored and blasting drilling and roof deep hole blasting according to different risk levels. Field application shows that: pressure relief measures can change the energy storage structure of surrounding coal and rock and effectively reduces the stress concentration in the coal pillars. The rockburst prevention effect is obvious.