Research On Fractured Deformation Characteristics And Control Mechanism Of Surrounding Rock On Deep Typical Gateways

With the increment depth of coal mining, the strata behavior severely, such as the characteristics of large deformation, lots of support deformation and failures, severe contraction(shrink) gateway section and so on during excavation and mining period. It was became a more and more important subject that studing on supporting mechanism of deep gateways and the supporting technology to ensure coal mine safety and efficient production, Based on the condition of13-1coal seam typical gateways and reseaching on the situation of the support and deformation of gateways'surrounding rock of Huainan deep mine, the destruction characteristic and control mechanism of surrounding rock were studied, Complex research methods were adopted such as in-situ measurement, similarity simulation,numerical simulation and theoretical analysis for mastering the destruction characteristic and control mechanism of surrounding rock on typical gateways under deep depth. The main research contents and results are as follows:1) Based on the surrounding rock conditions of deep typical gateways, by carring out the test of mechanics and in-situ stress parameters and studing strata behavior,its character was obtained.2) The three axials model test on deformation characteristic of typical gateway surrounding has been done in the State Key Laboratory Deep Coal Mine&Environment Protection.the strain,deformation and destruction character of four sections gateways with rectangle and straight wall semicircle arch type was obtained on condtions of different load pressure such as shallow and deep hydrostatic pressure, excavtion stress(k=1.5times to the depth of the900m hydrostatic pressure, the same after) and mining stress(k=2?4.5).The result shows:the strain on surrounding rock of gateway was changed from small,shallow tension and deep compression strain partition and tension strain area was gradually englarged under high stress.the conditions of stress partition were:roof and floor,load pressure between900m hydrostatic pressure and k?2and the semicircle arch type gateways is more prone to this phenomenon,the tension strain area were out of the anchor support during high stress.Floor heave monitoring shows that which was main caustion for floor heave deformation speed was high stress,a certain impact for the section shape different such as the semicircle arch type was smaller than rectangle, wire breakage shows the order of destruction was:sidewall was destroyed firstly and then damage transferred to floor angle,at last obvious separation was produced on roof. Reserved large deformation by larger section was acquired by the test.3) The result by numerical simulation on factors of stability on deep typical gateways surrounding rock shows:during excavation, strain softening was the main factors on stable of surrounding rock.The deformation of surrounding rock was more similar to site while Q=2.0(strain softening parameters) and constantly large tension plastic zone area appeared, Consistent with the model test results.(2) during mining period, the four factors'affection of stress on two sidewall's main roof were studied by single factor analysis and the laws were agained.(3) The depth was main factor to surrounding rock deformation by the variance methods.The expression of relation between four factors and depth were fitted,good correlation,it shows:the sidewall dformation increasd lineral with depth, roof and floor deformation exponential growth.The former enlarge faster than the later, the depth was going to900m,each section was simlar,therefore enhanced sidewall support was as same as roof support.4) Based on M-C, D-P criterion, strain soften, broken expansion, factors on soften area and expansion area range were studied,it shows:the influence to the range of soften and residual area,initial enlarge taken more actions than later enlarge by the same gradient(?Q=1GPa??Pi=0.15MPa).Based on D-P criterion,the strike high stress was one of the negative factors for two area.Take typical conditions parameters into the expression,the residual area was out of common anchor support length(?2.5m), sidewall support needs to be enhanced.5) Based on damaged theory and materials mechanics theory,"beam" model was made to analysis hard roof stability during mining period by deflection changed. The deflection increased quickly while the vertical stress on roof increased, and the distance of maximum deflection changed. Based on the maximum tensile stress criterion,tensile fracture characteristics of hard main roof were studied and largely belongs to tensile failure stage.6) In order to prevent tensile failure, the roof on sidewall angle were enhanced to reduce deflection. On the basis of solving steps of hyperstatic beams,deformation of main roof were studied by constraint relief measures,the rebound curve of main roof were acquired, the compression area could be expained by this theory.7) Based on stuy of defomation and destruction on surrounding rock deep typical gateways,"optimization of excavation direction","strengthen sidewall support and lateral roof suppot","optimization on section of gateways","different support stress during different area" were mentioned and support shceme was optimizated under similar conditions for severely defomation and destruction, after implemented, the deformation of surrounding rock gateways were reduced obviously, good effect has been acquired.