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深部煤层开采底板突水机理基础实验研究

Basic Experimental Study on Water-Inrush Mechanism of Floor in Deep Mining

【作者】 尹立明

【导师】 郭惟嘉;

【作者基本信息】 山东科技大学 , 采矿工程, 2011, 博士

【摘要】 本文从分析深部煤炭资源赋存环境入手,针对深部开采所呈现的高岩溶水压、高地应力及强采矿扰动和深部岩体力学新特性,以底板隔水层变形、破坏及构造活化形成导水通道为研究主线,综合运用室内试验、理论分析、数值模拟及现场实测等方法,开展了深部煤层开采底板突水机理的一系列相关基础性实验研究。通过对葛亭煤矿下组煤底板典型岩性岩石进行物理力学性质的室内试验和高、低围压下全应力应变渗透特性试验,对深部底板岩体阻水特性进行了分析,初步得出了岩性和围压对岩石渗透特性的影响规律。通过对岩石节理裂隙进行压剪条件下的渗流耦合特性实验室试验,研究了在恒定法向荷载(CNL)和恒定法向刚度(CNS)边界条件下,法向应力、节理表面粗糙度、渗透水压对试件应力、位移和渗流特性的影响,获得了剪切应力、法向位移、节理水力开度及透过率在剪切过程中随剪切位移变化的趋势和规律性;研究岩石节理裂隙在发生剪切变形时的剪胀特性,分析了节理剪切变形对渗流特性影响,获得了节理裂隙发生剪切破坏的判据公式。基于目前实验室研究岩体裂隙应力渗流耦合特性试验条件的限制,根据工程岩体受三维应力作用的实际情况,针对深部岩体所处环境的特殊性,初步设计开发了高水压岩石应力—渗流耦合真三轴试验系统。应用FLAC-3D数值分析软件对深部开采工作面底板随工作面推进的变形破坏演化规律和不同采深条件下的底板变形破坏特征进行了数值模拟研究,分析了断层影响下深部采场高承压水上底板流固耦合破坏特性,获得了一些规律性的认识,并用现场测试结果进行了验证,提出了模拟条件下断层防水煤柱的合理留设尺寸。分析了底板突水的多种影响因素和深部采场底板突水特点及形成原因,对深部采场底板突水类型进行了分类,以导水通道的形成为判据,提出了固有导水通道突水、正常岩层底板突水和断续节理裂隙扩展突水三大类底板突水模式,并逐一研究了其突水机理。应用突变理论研究了底板突水的突变特征,得出了底板系统突变突水的必要条件和充分条件。提出了阻突和促突变量因子及特征主导参量和系数的概念,通过分别建立底板因剪切破坏失稳和受水平力和垂直力作用而破坏失稳突水的突变模型,计算获得底板阻水系统状态,为深部煤层开采底板突水的预测预报提供了一种新的方法和思路。

【Abstract】 In this paper by analyzing the depositing environment of deep coal resources, according to high karst hydraulic, high ground stress, strong mining disturbance and new mechanical properties of deep rock presented in deep mine, deformation and failure of floor aquifuge and formation of underground watercourse caused by tectonic activation as the main clue, with the comprehensive application of laboratory test, theoretical analysis, numerical analysis and field measurement and so on, a series of related basic experimental studies on floor water-inrush mechanism in deep mine are carried out.Based on laboratory experiment on the physics mechanical property of typical floor rock which from lower coal seam of Geting coal mine and complete stress-strain seepage properties test of floor rock under high or low confining pressure, combined with analysis of water-proof property of floor strata in deep mine, we preliminarily obtained the influence law of lithology and confining pressure to rock seepage property. By laboratory experiment on rock mass joint and cracks seepage coupling property under conditions of compression and shear, researched on the influence of normal stress, roughness of joint face, seepage pressure to samples’stress, displacement seepage property under constant normal load(CNL) or constant normal stiffness(CNS), we got the trend and regularity in shear process shear stress, normal displacement, jointed hydraulic aperture and transmissivity changed with shear displacement. Researched on the dilatancy property of rock joint fractures had shear deformation, analyzed the influence of joint shear deformation to seepage property, criterion formula about joint fractures had shear deformation are obtained. Based on the present laboratory condition’s limit to rock fracture stress seepage property, according to the actual situation of rock mass under 3d stress and the environment specificity of deep rock mass, rock stress-seepage coupling true triaxial test under high pressurized water was preliminarily designed and developed. The evolution rule of deep mine floor’s deformation and damage with the working face advanced and the features of floor’s destruction under different mining depth are analyzed though numerical experiment using FLAC-3D, the fluid-solid coupling damage characteristics of floor which influenced by fault and above pressurized water in deep mine were analyzed, some regularity cognition is obtained and verified by field test results, the reasonable size of fault waterproof coal pillar under simulation condition is put forward. The influence factors, characteristics and the reasons of floor water inrush in deep mine is analyzed and deep stope floor water inrush types are classified. According to the formation of water inrush passageway, three modes are put forward as inherent passageway water inrush mode, normal floor strata water inrush mode and discontinuous joint fissure extension water inrush mode, and then their water-inrush mechanism are researched. Catastrophe characteristics of floor water-inrush are studied with the help of the method of catastrophic theory, necessary and sufficient conditions of floor catastrophe water-inrush are derived. Some concepts as Water-proof variables factor, feature leading parameter and coefficient are put forward. Through establishing catastrophic models respectively, one model is floor water-inrush for shear failure instability, and the other is floor water-inrush for vertical and horizontal force and destroy instability, floor system state is calculated and obtained, and it can provide a new method and idea for predicting water-inrush from floor in deep mine.

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