【作者】 杨伟峰；

【导师】 隋旺华；

【作者基本信息】 中国矿业大学 ， 地质工程， 2009， 博士

【摘要】 溃砂或水砂突涌是薄基岩厚松散含水层条件下采掘时含砂量较高的水砂混合流体溃入井下工作面并造成财产损失及人员伤亡的一种矿井地质灾害。溃砂或水砂突涌产生的机理与影响因素与一般意义上的矿井水害不同,应作为一种独立的矿井地质灾害种类来对待。本文围绕“薄基岩采动破断及其诱发水砂混合流运移特性研究”这一科学问题,以山东太平煤矿厚松散含水层薄基岩含煤地层为地质原型,分析了矿区地质、水文地质与工程地质条件及薄基岩特征,明确了薄基岩的涵义,建立了工程地质模型,分析了煤层采动薄基岩破断的机理,归纳总结了薄基岩厚松散层下开采水砂流涌出通道形成的三类工程地质模式;设计并制作了水砂混合流运移及突涌试验模型,模拟了采矿覆岩体裂隙通道中水砂混合流在运移与突出过程中的启动、运移和稳定的全过程,研究了煤层开采水砂混合流运移特性与动力机制。本文取得的主要创新成果有:(1)揭示了不同岩性组合薄基岩的采动破断机理。薄基岩厚覆盖层下采煤属于特殊地质条件下的开采问题。在详细研究和总结研究采区的主要地质特征的基础上,通过模型试验和数值模拟,获得了研究区开采覆岩破坏的基本规律以及“三带”的发育特征。工程地质力学模型和相似材料模型试验结果揭示了含煤地层不同岩性组合薄基岩采动破断机理;有限元数值模拟显示了覆岩(土)中的应力与应变分布情况;离散元模拟分析得到了覆岩运动规律及工作面周期性的来压现象。结果表明,在薄基岩条件下,导水裂隙带容易贯通基岩,直接波及到覆盖层底部的含水层,导致工作面突水涌砂。(2)设计并制造了水砂混合流运移及突涌模型。该模型能够模拟出地下采矿覆岩体通道中水砂混合流在运移与突出过程中的启动、运移和稳定的过程,方便用于研究水砂混合流运移中周围岩体与水砂混合流的动力耦合关系。(3)通过模型实验,研究了水砂混合流在采动裂隙通道中的运移与通道大小、颗粒尺寸、出砂口大小等的定量关系。通过设置不同水砂混合物成分、不同水压力、不同裂隙通道宽度的模型试验,定量化地研究了水砂混合物运移及涌出的多种地质信息,得到了不同模型试验水砂混合流运移通道中不同位置监测的水压力变化曲线,同时得到了裂隙通道水砂流速度与通道宽度的关系,即同一种水砂流运移速度随裂隙通道的宽度增加而降低,在裂隙宽度相同的情况下,水砂流运移速度又随颗粒逐渐变细而增大;观测得到了水砂流通道溢出口出砂量与时间的变化关系,即涌出物的含砂量随时间延长而减少,刚开始水砂涌出物中含砂量大,含砂量较大的状态持续时间短;随着试验时间推移,渗透变形破坏的不断完成,涌出物的含砂量也渐渐减小,最后至塌陷漏斗形成后,涌出物中含砂量渐变为零。(4)研究了不同通道类型水砂流运移特征,提出了水砂流运移的三个阶段及三种水砂突出类型。根据煤层采动引起覆岩破坏形成的垮落带、导水裂缝带通道情况,将水砂混合流运移通道侧壁面分为平直光滑无充填的、粗糙起伏无充填的及有充填软弱泥质物质的三类,并针对这几种形态进行了模型试验。试验以0.05MPa和0.1MPa水压力条件下的不同通道裂缝宽度、不同倾角、不同通道侧壁形态为例,揭示了孔隙水压力在裂隙通道中不同位置的变化特征。突水涌砂在采空区是瞬间发生的,在裂隙通道内,根据孔隙水压力的变化,将水砂混合流运移过程分为相互关联的三个阶段:上升阶段、稳定阶段及突出阶段。总结了水砂混合流突出阶段的水压力变化曲线的特征,划分出了三种水砂突出类型:直泻式突出型、跳跃式突出型和缓坡式突出型。由此,探索了水砂混合流运移特征及动力机制。更多还原

【Abstract】 The mixed water and sand flow inrush is a common type of geological hazards in underground coal mines adjacent to unconsolidated aquifers, which should be regarded as an independent type of mining hazard due to its special mechanism, influencing factors and treatment methods.This paper focuses on the overburden failure in the thin bedrock and the characteristics of the mixed water and sand flow induced by coal mining, choosing Taiping coalmine as a geological prototype. The mine geology, structural formation, hydrogeology, engineering geology and characteristics of the thin bedrocks were analyzed. The meaning of the thin bedrock was clearly defined. Based on the geological prototype, an engineering geological model can be taken to explore the rupture pattern and the failure features when mining under the thin bedrock. Three engineering geological modes of the mixed water and sand flow transfer induced by coal mining under the thin bedrock and thick unconsolidated aquifers were concluded and summarized. A test model of the mixed water and sand flow transfer and inrush was designed and used to simulate the startup, transfer and inrush process of the mixed water and sand flow in the overburden fractured channel. The transfer characteristics and dynamic mechanism of the mixed water and sand flow induced by mining were researched. The main achievements of this paper are as follows.(1) The failure features induced by mining of the thin bedrocks with the various lithological structures were investigated. The main geological characteristics and safety mining problem of the study area were researched and summarized in detail. The overburden failure and development characteristics of“three zones”in the study area were obtained through model tests and numerical simulations. The engineering geomechanics model and scaled model test results revealed the failure law in the thin bedrock with different lithological structures. The distribution of stress and strain was obtained through the finite element numerical simulation. The overburden movement and the periodic roof pressure of overburden were analyzed by the discrete element model. The water flowing fractured zone easily transfixes bedrocks under the condition of the thin bedrock and directly sweeps the Quaternary bottom aquifers. It would cause the water and sand inrush into underground workings.(2) The test model of the mixed water and sand flow transfer and inrush was designed and manufactured. The model can be used to simulate the startup, transfer and inrush process of the mixed water and sand flow in the overburden fractured channel. The water-rock stress coupling of the cracked surrounding rocks and the mixed water and sand flow was then conveniently researched.(3) The quantitative relationships among fractured channel width, particle size, outlet size and the mixed water and sand flow transfer in the overburden fractured channel were researched by the test model. Geological information of the mixed water and sand flow transfer for the various compositions of the flow, water pressure and the channel feature was quantitatively studied. The water pressure variation curves in the different positions were gained from different model tests. The relations between the channel width and the velocity of the mixed water and sand flow in the fractured channel were analyzed, showing that the velocity of the same mixed water and sand flow decreased with the increase of the fractured channel width. In the condition of same fractured channel width, the velocity of the mixed water and sand flow increased with the decrease of the particle size. The relationship between time and sand production volume of the mixed water and sand flow channel overflows was obtained from observational results, namely the sand content of gushing material decreased with time prolonged. Just at the very beginning the sand content of gushing material was large. With the test time and the process of seepage deformation and failure, the sand content of gushing material decreased gradually. Finally, the collapse doline formed and the sand content of gushing material became almost zero.(4) The characteristics of the mixed water and sand flow in the various types of fractured channels were researched. Three stages of the mixed water and sand flow transfer and three types of the mixed water and sand inrush were brought forward. Based on the caving zone and water flowing fractured zone channel of overburden failure by mining, the transfer channel sidewalls of the mixed water and sand flow were divided into three types; the straight and smooth with no filling, rough and stepped with no filling and filling with soft mud substance. The model tests were carried out through the three types. The variation characteristics of water pressure in different position of the fractured channel were revealed by considering the variations of the width, inclination angle, and sidewall types of the fractured channel under the water pressure of 0.05MPa and 0.1MPa. The results show that the water and sand inrush took place instantly in the mined area. Based on the characteristics of water pressure variations, the transfer process of the mixed water and sand flow in the fractured channel was divided into three interdependent stages: the increasing stage, stability stage and outburst stage. According to the characteristics of the water pressure variations during the mixed water and sand flow inrush, the mixed water and sand flow outburst was divided into three basic types: the direct injection outburst type, the saltatory outburst type and the gentle slope outburst type. Therefore, the transfer characteristics and dynamic mechanism of the mixed water and sand flow were explored.更多还原