华北煤田下组煤底板岩溶含水层注浆改造技术应用及发展趋势

Application and Development Trends on Grouting Reconstruction Technology for Floor Karst Aquifers of Lower Group Coal Seam in Northern China Coal Field

我国华北煤田含煤地层主要为石炭—二叠纪。由于煤系地层绝大多数直接沉积在奥陶系灰岩强承压岩溶含水层之上,其下部煤层(下组煤)距离奥陶系灰岩较近,开采过程中多次发生底板突水事故。为此,我国专家学者开展了大量的研究工作,在下组煤底板突水危险性评价理论和方法方面取得了丰富的研究成果。但是,由于华北煤田分布广,地质水文地质条件千差万别,这些理论和方法存在一定的局限性,下组煤突水事故仍时有发生。因此,下组煤底板岩溶含水层注浆改造成为近年来我国煤炭行业重点研究的课题之一。首先系统地介绍了我国下组煤底板岩溶含水层大面积注浆改造布孔方式发展历程,即由井下巷道扇形钻孔→井下巷道定向钻孔→地面定向钻孔;其次介绍了放水试验法、钻孔涌水量法和电阻率CT、震波检层、无线电波透视与瞬变电磁等物探方法在下组煤底板岩溶含水层大面积注浆改造效果评价中的应用状况;最后指出了未来下组煤防治水技术的发展趋势:(1)在进一步深入研究底板突水理论的基础上,研究浆液和下组煤底板岩溶地层的相互作用机理;(2)采用地面定向钻孔方式,对下组煤底板岩溶含水层进行注浆改造,优化注浆工艺;(3)结合水平定向钻孔工艺,研究经济高效的物探技术,实现对深部下组煤底板突水危险性和底板岩溶含水层注浆改造效果的精准探测与评价。

The main strata of coal measures are Permo-Carboniferous in the Northern China Coal Field （hereafter,NCCF for short）.Because the strata of coal measures are most directly deposited on the strong karst aquifer of Ordovician limestone,and the stratum between lower group coal seam （hereafter,LGCS for short） of Permo-Carboniferous and Ordovician limestone aquifer is very thin;and many floor water-inrush accidents occurred in mining LGCS.For this,Chinese scholars have conducted a lot of research work of theories and methods on water-inrush risk evaluation for the floor of LGCS in NCCF,and have obtained abundant research results.Because of the wide distribution of NCCF in Chinaand the different geological and hydrogeological conditions of coal mines,at present,any one of water inrush theories and methods has certain limitations and particular conditional requirem ents for its implementation,floor water inrush accidents still happen occasionally.Therefore,the grouting reconstruction technology for the floor aquifers of lower group coal seam becomes one of the key research topics in Chinese coal industry in recent years.This paper firstly made a systematical introduction the development course of boreholes layout for large-area grouting reconstruction of the aquifer in coal seam floor,which has progressed from fan-shaped boreholes opening in underground roadway,directional boreholes opening in underground roadway,to directional boreholes opening on the surface;secondly,it introduced the application status of dewatering test method,borehole outflow rate method and geophysical techniques （such as electronic resistivity CT method,detection layer with seismic wave,radio wave penetration tomography,transient electromagnetic,and so on） in evaluation the effect of largearea grouting reconstruction of the floor of LGCS;thirdly,it pointed out that development trends on the technology of water prevention and control in LGCS floor in the future,it includes：（1） based on further study of the mechanism of water-inrush from coal seam floor,studying the interaction between grout and floor strata of LGCS;（2） using the way of directional borehole opening on the surface to grouting reconstruction of the floor strata of LGCS,and optimizing the grouting process;（3） combined with horizontal directional drilling technology,researching the economic and efficient geophysical prospecting techniques to achieve accurate detection and evaluation for the water inrush risk of LGCS floor before and after grouting reconstruction.