老采动区覆岩裂隙发育特征及活化机理研究

Crack Development Characteristic of Rock Strata over Abandoned Gob and Its Activation Mechanism

采用钻孔勘探、钻孔电视、地球物理测井、岩石力学测试等技术和方法对老采空区覆岩裂隙发育特征进行了研究。研究结果表明:老采空区弯曲带岩层的整体性未遭破坏,表现为连续平缓的弯曲变形,局部有裂隙产生;裂缝带岩层产生裂隙或断裂发育,但尚未塌落;垮落带岩层断裂破碎塌落,有残留空洞发育。对其中的53条采动裂隙发育特征统计显示,裂隙平均间距1.08m,间距小于2.0m的裂隙占统计数据的85%,老采动区采动岩体裂隙以低角度裂隙为主,倾角小于30°的裂隙占统计数据的68%;煤炭开采引起的地下空洞、离层、裂隙和垮落带的欠压密、孔隙饱水等现象是老采动区活化的根本原因。

This paper researched characteristic of crack in overlying strata over abandoned gob by borehole exploration,borehole TV,geophysical well logging,rock mechanics test,et al.Results was shown as follows.Rock in bending zone over abandoned gob was intact and took on continuous bending deformation with local cracks.Cracks developed in crack zone but rock didn＇t cave.Rock parted and caved in caving zone.Statistics from 53 cracks induced by mining showed that average interval of the cracks was 1.08m and cracks whose interval less than 2.0m was 85% of total data.Cracks in overlying rock over abandoned gob were mostly small dip.Dip less than 30°was 68% of total data.Underground cave,parting,cracks induced by mining,under-consolidation and aqueous pore in caving zone were basic cause of abandoned gob activation.