侏罗-白垩系覆岩采动主控裂隙演化及突水机理

The overlying strata of Jurassic thick or extremely thick coal seam is weakly consolidated in northwest China. The high-strength coal mining induces tremendous mine rock pressure and water inrush with large flow greater than 1000m3/h from Cretaceous aquifer with huge thickness (200-500m) and high water pressure (3-5MPa). The analysis results indicate that the water inrush disaster is controlled by the evolution of master fractures, which consist of transverse separation layer fractures and vertical main water-flowing fractures. Taking typical collieries of Huanglong and Dongsheng mine area as an example, centering on the issue of "evolution and water inrush mechanism of master fractures", this project studies the spatial occurrence and engineering geological properties of Jurassic and Cretaceous overlying strata. The evolutionary process and geological hazard pattern of master fractures will be revealed by physical and numerical simulation. The study on the evolution of seepage characteristic of master fractures in the mining overlying strata will be carried out in the aspects of height forecast of water-flowing fractured zone, rules of mining rock seepage breaking, fracture seepage characteristics of rock in loading and unloading test or with high water pressure, time effect test of mining fissure seepage, etc. And the study will establish the seepage model of the mining Jurassic and Cretaceous overlying strata in order to reveal the permeability evolution and water inrush mechanism of master fractures in the mining overlying strata under liquid-solid coupling effect. The forecast theory and control technology of water inrush due to master fractures in the mining overlying strata are put forward. It provide scientific basis for disaster prevention due to large scale coal mining involving water hazard control, water resources protection and capacity layout optimizing in Northwest China.

我国西北侏罗系厚及特厚煤层覆岩具有弱胶结的特点，高强度开采引发工作面强烈矿山压力显现并伴随高位的白垩系巨厚（200-500m）、高压（3-5MPa）含水层大流量（大于1000m3/h）涌突水。分析表明此类矿井水害是受主控裂隙（横向离层裂隙和纵向主导水裂隙）演化所控制的灾害。本课题以黄陇、东胜煤田典型矿井为例，围绕“采动主控裂隙演化及其突水机理”这一科学问题，研究煤层侏罗-白垩系覆岩空间赋存及工程地质性质；通过物理和数值模拟等，再现主控裂隙演化过程与致灾类型；从导水裂隙带高度预测、采动岩层渗流破断规律、加卸载和高水压下的裂隙岩石渗流特性以及采动裂隙渗流时间效应方面，揭示侏罗-白垩系覆岩采动主控裂隙突水及其渗透性时效演变内在机理，并建立采动覆岩渗流模型。研究提出采动主控裂隙突水预测预报理论方法和防控技术措施，为我国西北大型煤炭开采水害防治、水资源保护和优化产能布局提供基础科学依据。

随着我国西北侏罗系厚及特厚煤层的开采，出现一类较为复杂的灾害，主要表现为工作面强烈的矿山压力显现伴随高位白垩系含水层大流量涌突水，突水瞬时量大、衰减较快，且具有周期性特征等。本项目围绕此类问题，以鄂尔多斯煤盆地西南缘的彬长矿区和永陇矿区典型矿井为例，开展了白垩系巨厚、高压含水层和侏罗系软弱泥质顶板覆岩岩体结构、水岩接触类型研究，构建了采动工程地质孕灾模型。通过数值模拟、物理模拟和试验方法，结合现场观测数据，揭示了煤层采动覆岩结构、主控裂隙演化机制，获得了岩体主控裂隙、覆岩大结构、基本顶断裂和矿山压力显现之间的相互关系，进而揭示了老顶-亚关键层断裂、矿山压力显现、主控裂隙、涌突水量、充水含水层水位之间的联动机制；通过室内试验和现场实测，构建了主控裂隙-网络裂隙岩体渗流模型，揭示了侏罗-白垩系覆岩采动破断和主控裂隙控制下的渗流特性机制，阐述了强渗透压-岩体破断-矿压-涌水过程，预计了工作面开采过程中的动态涌水量，揭示了采动主控裂隙突水的突（涌）水机理及其时效性演化内在机理；最终研发了侏罗-白垩系覆岩采动主控裂隙突水预测预报方法和防控关键技术，并在研究区成功实施。