Distribution pattern and influencing factors of in-situ stress for deep levels in Shoushan No.1 Coal Mine
To investigate the distribution pattern and influencing factors of in-situ stress for deep levels in the Shoushan No.1 Mine,according to the measured in-situ stress data of the mine,the tectonophysics and rock mechanics and numeric-al simulation methods were applied to study the type,magnitude and direction distribution pattern of in-situ stress.The distribution characteristics of in-situ stress field was simulated.The effect of buried depth,lithology and geological struc-ture on the in-situ stress distribution was analyzed.The main factor of in-situ stress distribution was determined.The re-search shows that the in-situ stress values obtained by the multiple regression analysis of inversion method are consistent with the measured values.The relative error is less than 20%and the results are reliable.The coal and rock mass of mine is in a state of three-dimensional compressive stress.The principal stresses relation of coal seam is SH＞SV＞Sh.The in-situ stress increases firstly,then decreases and finally increases from the north to the south of the mine.The magnitude of in-situ stress is 28-44 MPa and belongs to the high stress level.The in-situ stress direction is NEE.The buried depth controls the magnitude and type distribution of the in-situ stress.With the increase of buried depth,the principal stress is increas-ing and the stress field type has the changing tendency from the dynamic stress field to quasi-hydrostatic pressure field.The lithology has a closely relationship with the in-situ stress.From mudstone to sandstone or limestone,the in-situ stress is increasing.The larger the elasticity module is,the higher the in-situ stress is.The difference of stratum lithology causes the discrete distribution of in-situ stress and the deflection angle of in-situ stress direction is less than 10°.The relation between the in-situ stress and the buried depth and the elasticity modulus is expressed as σH=0.0350H+0.4681E-8.5513 in the mine.The geological structure is the main controlling factor of in-situ stress in the mine.The fold shape controls the horizontal stress distribution of the in-situ stress.The in-situ stress of the syncline inner arc is more than that of the anti-cline inner arc.With the increase of the fold crook degree,the in-situ stress of inner arc increases gradually,and its stress gradient increases gradually.The in-situ stress of fault zone is decreasing and the in-situ stress of the fault pinch-out side is greater.The in-situ stress direction deflects along the fault strike.The larger the angle between maximum horizontal prin-cipal stress and the fault strike is,the greater deflection angle of maximum horizontal principal stress direction is.The in-situ stress of the tectonic association zone of fault and syncline is more than that of the tectonic association of fault and an-ticline.The tectonic association causes the undirectional distribution of the in-situ stress direction.
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