Research Of Mining Dynamic Loading Effect And Its Induced Rock Burst In Coal Mine

The process of mining dynamic load inducing rock burst in coal mine lacks of systematicresearch at present. This paper using a combination research methods of theoretical analysis,in situ tests, laboratory tests, numerical simulation and engineering practice systematicallystudied the characteristics of mining dynamic load, mechanism of which in inducing rockburst and reducing the role of dynamic load in rock burst prevention.Studies have shown that in-situ stress field is the basis of static load, and the stress nearthe mining space has a basic form of distribution. The mining activities and coal-rock dynamicresponses of coal mining are the main sources of dynamic load. Dynamic loading strain rateand rock burst released energy have a positive correlation. Coal mining dynamic loading strainrate is generally not more than the level of10-1/s, accordingly the load states are defined ofcoal mine.Coal and rock strength and elastic modulus increase exponentially with loading strain rateincreasing, and the presses energy input the coal and rock samples before and after destructionexponentially increase with strain rate increasing, while the dynamic failure time decreasessharply, and burst tendency increase largely with strain rate increasing. When static load is low,the destruction of the coal samples needs a strong dynamic load or cyclic dynamic load of acertain intensity, while at a higher static load, smaller dynamic load can lead the coal sample todamage. The phenomenon of acoustic emission showed strong Kaiser effect in loading of coaland rock samples. Under dynamic load, the coal and rock samples have demonstrated a severefracturing before peak stress.When the damage factor reaches the critical value of coal or rock, the coal or rock willperformance of instant overall destruction. Under static load, the coal and rock havepredominant direction of crack propagation and damage occurred mainly in a local area. Therange of crack propagation direction can be increased by increases the principal differentialstress. Under dynamic loading, stress magnitude and direction change over time, while thecoal-rock crack propagation advantage direction is also changed, and the range of coal androck damage is increased. The larger the magnitude, the lower the frequency, and the longerthe duration of the dynamic load is, the greater the damage of coal-rock is. In the process ofrock burst, static load mainly provides the energy of coal and rock for damage and bursting,while the dynamic load mainly triggers damage to bursting. The dynamic load effect in rockburst formation is causing coal-rock to exacerbate damage, making the structural planedeblock to slip, and leading coal body near the surface reflect seismic wave to cause tensilestress to lead instability of coal and rock mass. Rock burst "Five Inducing Factors" is promoted in this work. Accordingly, the fivefactors interaction on a certain situation induces rock burst. From time-varying dynamics andthe static mechanics points of view, separately established criterions of rock burst whichexplained the lagging appearance of rock burst. The research work also analyzed thedisturbance form of dynamic load, stated the coal and rock critical antidisarrangement ability,revealed "force and energy deblocking" rock burst mechanism, presented the requirmentsprovided by the structural strength anisotropy of coal and rock, and analyzed several tipicaltypes of deblocking form.In rock burst monitoring and prevention, this paper promoted the thought of static anddynamic load combined monitoring, and pointed out that dynamic load should be observedfrom the source and the coal and rock response of dynamic load, and introduced rock burstmonitoring key technologies, and analyzed monitoring precursor law of rock burst underdynamic load, and proposed rock burst prevention principle by reduce effect of dynamic load,that is reducing the propagation and of effect of dynamic load so as to avoid or weaken rockburst, moreover, this paper also studied the key technologies of reducing dynamic load, andproposed the roadway support form of―elastic-overall-high strength and storage bearer".Finally, the research results were put to practice usage in the Taoshan coal mine. The practiceresults showed that the rock burst prevention and control theory and technologies based onreducing the effect of mining dynamic load has a remarkable effect.There are111figures,22tables and225references in this paper.