井-地-孔联合微震在多煤层开采顶板断裂高度监测中的研究

Study onApplication of Underground-Surface-Borehole Joint Microseismic Technology in Multi-Seam Coal Mining Roof Fracture Height Monitoring

华北煤田西部鄂尔多斯侏罗系煤田顶板水害严重,而其导水裂缝带高度是评价顶板水害程度的关键水文地质参数,因此准确测定导水裂隙带发育高度是顶板水害防治的关键技术。井-地-孔联合微震监测技术具有实时、连续、动态、长期监测的优点,可以在地面、井下和孔中等位置布置传感器,形成对测区的全方位监测,具有比传统微震监测技术更高的定位精度,尤其是垂直方向的定位精度更高,能够满足防治水的要求。以布尔台煤矿42202工作面为例,在地面和井下巷道同时布置传感器,构建了井-地联合微震监测系统,对工作面回采过程中顶板裂隙发育高度进行实时监测,监测结果表明:42202工作面回采时顶板岩层破裂产生的地震波能够顺利穿越上组煤采空区到达地面,被仪器接收。此次监测回采工作面长800m,工作面回采过程中顶板裂隙发育高度为150~160 m,其测量结果与钻孔实测法获得的结果一致,而且工作面靠近未采区域侧的顶板裂隙比靠近采空区侧的更发育。研究表明利用井-地联合微震监测技术可以对工作面回采过程中顶板裂隙发育高度进行实时、高精度监测,对于顶板水害防治具有重要意义和实用价值。

Jurassic coalfield coal roof water hazard is severe in the Ordos Basin,North China.The water conducted fracture zone height is a key hydrogeological parameter to assess roof water hazard level.Thus to correctly determine water conducted fracture zone developed height is the key technique in roof water hazard control.While the underground-surface-borehole joint microseismic monitoring technology has strong points of real time,continuous,long term monitoring,and layout sensors on surface,underground and boreholes to form surveying area all-round monitoring.It has higher positioning accuracy than traditional microseismic monitoring technology,especially in vertical direction positioning to satisfy water control requirements.Taking the Burtai coalmine coal face No.42202 as an example,to lay out sensors on surface and underground roadway simultaneously,has constructed underground-surface joint microseismic monitoring system,carried out roof fracture developed height real time monitoring during the coal face winning process.The monitoring result has shown that the coal face winning roof rock fracturing produced seismic wave can pass through upper coal group gob area get to surface smoothly and received by receiver.The coal face in this monitoring has 800m long,during the winning process roof fracture developed height is 150~160m,the result is consistent with drilling actually measured result;furthermore,roof fracturing developed height of coal face close to never winning side is more developed than close to gob area side.The study has shown that to use underground-surface joint microseismic monitoring technology can carry out real time,higher accuracy monitoring for coal face winning process roof fracturing developed height,thus has significance and practical value in roof water hazard control.