The Old Mining Area And Surrounding Rock Stress Distirbuiton Numerical Simuylation Study

In this paper, the ShanXi coal group, China coal industry limited companyof coal mining area of two3#old mining face for the first time the actualgeological data as the foundation, through the theoretical calculation, numericalsimulation of RFPA combination, on the old mining area: left coal pillars, theold mining roadway, and the size of the influence factor of old; mining twomining excavation and old mining roadway safety coal pillar width and thestress, displacement distribution of the old mining area; the first two miningcoal working surface pressure distribution. Based on the above research, thefollowing conclusions:（1）The use of theoretical analysis, simulation of coal pillar and3Dnumerical obtained:①the old mining area of the left coal pillars in the moststable state; the old mining roadway gob, gob area. Most of the.②lane width,Lane1,2high, coal pillar width on the left coal pillars and mining roadway ofthe old state have a certain impact, influence by coal pillar width of coal pillar ismainly affected by the state, the next is high near the tunnel, lane width; the oldmining roadway is mainly affected by the high roadway and the influence of thelane width. （2） Through the method of numerical simulation, studied the old miningarea of two coal heading face stress, displacement distribution. Concluded that:①with the increase of old mining roadway, roadway safety coal pillar widthincreases, the safety of coal pillar width is5m, the width of coal pillar safe airzone is15m, take the coal pillar safe distance falls area is20m;②the twotunneling working face, stress basically than before excavation, excavationdisplacement to lower than before, the old mining roadway, stress, displacement,the greater the rate of change.③in the coal pillar width is less than and greaterthan the safety coal pillar width, stress, displacement distribution difference isvery obvious. Is less than the safe coal pillar width, stress decreasing area islarge, there is only one large displacement is greater than the peak; safety coalpillar width, stress decreasing area smaller, generally there are two peakdisplacement.④when the coal pillar width exceeds the safe coal pillar width,the stress, displacement variation rate changed little.（3）Through theoretical analysis and numerical simulation method tostudy the initial pressure distribution, obtained the following results:①according to the theoretical calculations show that the normal mining firstweighting step distance is8.13~11.50m, the numerical simulations of the firstweighting step distance is11m.②from the stress distribution can be seen in thefigure, to pressure the stress distribution law and the future pressure of differentpressure, the maximum stress value is higher than the maximum pressure valuein the future, and the minimum value is more obvious than the future pressure when the minimum value is small.③with the increase of old mining roadwaysection, two mining influenced by old mining roadway is large, mainly in, thefirst weighting step distance is smaller; the maximum stress is more and morebig, the stress concentration factor is also more and more big; working face forthe first time breaking step distance is more and more small; in front of theworking face roof distance is more and more big, also a corresponding increasein difficulty; stress decreasing range is also more and more.④when the oldmining roadway is constant, with the increase of distance, the old mininginfluence on working face roadway tends to be stable, the old mining influenceon working face roadway has a critical value, the value of more than two,continue to increase the distance, in the initial pressure distribution basicallyunchanged.