基于浅表水环境保护的南方岩溶煤矿开采基础理论研究

The water leakage in karst region is one of the problems to coal mine in south China. Surface water leakage can not only lead to serious environmental disruption, but also bring enormous security hidden trouble to coal mine. This project aims to research the basic theory of coal mining for surface water environment protection in karst region of south China by theoretical analysis，lab experiment，physical simulation，numerical simulation and field testing. By analyzing the relationships between rock fracture and extension evolution of rock crack in this project, the strata rupture rules under the condition of non-full mining and the motion space-time evolution laws will be revealed，and the laws of fissure extension，rock stratum damage and collapse of karst cave rock mass under the influence of mining will be clarified，and the water conducted and water gushing mechanism throught underground watercourse will be established. According to the rock mass movement rules by different recovery methods, this project will reveal a touch mechanism that coal mining of karst mine area impact on surface water environment, and will put forward a formation condition and control action mechanism of waterproof key stratum, and will set up an integration water-preserved-mining mode of water disaster prevention and water resource utilization to coal mine in south China. Furthermore, it will analysis the key factors of coal mining cause south karst mine surface water environment disruption, and will build an integrated assessment models with the effect on non-linear，multi-factor and multi-field coupling. Taking a typical karst mine region as cases，it will reveal the impact of coal mine on the surface water environment，and will put forward appropriate methods for regional water-preserved-mining.

岩溶矿区水资源漏失是南方煤矿开采所面临难题之一，浅表水漏失不仅会引起突出的环境破坏，而且也给矿山开采带来巨大的安全隐患。本项目采用理论分析、实验室试验、物理模拟、数值模拟和现场测试相结合的综合研究方法，进行基于浅表水环境保护的南方岩溶煤矿开采基础理论研究。通过分析岩层宏观破断与岩石裂隙扩展演化关系，揭示非充分开采条件下岩层破断与运动时空演化规律，阐明采动条件下的岩溶洞岩体的裂隙扩张、岩层破坏及塌陷规律，研究导水通道的导涌水机理；根据煤炭开采方式所引起的岩体移动规律，揭示岩溶矿区煤炭开采对浅表水环境影响的触动机制，提出隔水关键层的形成条件和控制作用机理，研究南方矿井水害防治与水资源利用一体化的保水开采模式；分析煤炭开采对南方岩溶煤矿浅表水环境破坏的关键因素，构建非线性多因素多场耦合作用的综合评估模型。以一典型岩溶矿区为例，揭示煤炭开采对浅表水环境的影响，提出适宜的区域性保水开采方法。

本项目以南方岩溶煤矿开采为工程背景，分析了采动条件下岩层的破断规律，得到了随采动影响不断向上发展的采动裂隙动态发育规律；以关键层理论为基础，应用数值模拟探讨了关键层对导水裂隙带发育高度的影响；以采动裂隙以及导水裂隙为基础建立了岩溶煤矿岩溶洞裂隙破坏的分析模型。研究了岩溶裂隙与岩溶水压与采动裂隙的相互作用，提出不同的岩溶水压导致不同的岩溶水流失速度，且存在安全的水头值，即当岩溶洞内水压力值小于安全水头值时，岩溶水漏失速度处于较低水平，一旦岩溶洞内水压力值超过安全水头值，岩溶水漏失速度会出现激增，影响矿井安全生产以及浅表水生态平衡，并据此提出了“疏水抗压开采”和“局部注浆，降压开采”的方式。通过相似模拟分析了岩溶洞裂隙在采动作用下的破坏特征，非均匀的采动作用使得岩溶洞顶板破坏，岩溶洞顶板岩层在岩溶洞处的下沉值异常增大，最终造成岩溶洞顶板上方采动裂隙发育高度较大，从而使岩溶洞上方产生抽冒现象。通过还原浅埋岩溶塌陷的过程，提出岩溶地表塌陷的本质是地表土层的破坏和流失，岩溶上方覆盖层厚度对岩溶地面塌陷有重要影响，并且指出在开口岩溶洞形成后，不发生岩溶地表塌陷的必要条件是岩溶上方覆盖层厚度必须大于地裂缝极限发育深度与土洞极限平衡高度之和，并采用弹性力学理论建立了土洞极限平衡高度以及地裂缝极限发育深度的计算公式。针对岩溶地区的伴生断层，建立了断层面应力计算公式，理论分析了断层面应力的影响因素，工作面推进长度小于某长度Li时，断层面应力逐渐增加，大于Li后其应力不再增加。因此可通过计算不同推进长度下断层面上的应力变化特征来确定工作面与断层之间的安全距离。