采动影响下陷落柱渗流演化规律试验研究

发布时间：2018-06-27 10:41

本文选题：陷落柱 + 填隙物　；参考：《中国矿业大学》2016年博士论文

【摘要】：华北地区一直是我国重要的煤炭基地,华北型煤田受岩溶强含水层威胁煤炭资源量巨大,矿井奥灰水害日趋严重。陷落柱作为我国华北地区一种特殊的地质构造,多发育于奥陶系石灰岩,易成为垂向导水通道而建立煤层底板和奥灰水的水力联系引发大型突水事故。同时,陷落柱突水具有隐蔽性、滞后性和突发性等特点,难以进行预测和防范,因此研究采动影响下陷落柱的渗流演化规律及突水机理具有十分重要意义。本文以陷落柱为研究对象,综合采用理论分析、室内试验和数值模拟相结合的方法,对固结和采动状态的陷落柱填隙物及底板隐伏陷落柱的渗流特性开展了一系列的研究,对陷落柱水害防治具有一定的指导意义。(1)通过土工试验固结方法制备了陷落柱填隙物样品并测试了其固结状态的渗流特性。陷落柱填隙物固结状态下全应力-应变过程中渗透率呈现出减小-增大-减小的变化规律,陷落柱填隙物的初始渗透率随着固结压力的增大和初始含水率的减小而减小,渗透率峰值与围压间存在指数函数关系。(2)通过陷落柱采动状态的渗透性试验研究了陷落柱突水的突发性和滞后性。通过陷落柱采动状态下的渗透性测试分析了渗流边界和有侧限轴压对渗透率、启动水力梯度和颗粒流失质量的影响规律,提出大颗粒流失导致骨架结构失稳是发生渗流突变现象的根本原因,并基于非达西流推导讨论了非达西流β因子的意义。基于采动影响下应力场的变化规律,提出陷落柱突水的滞后性是由于采动影响下破碎岩体的压实作用、二次破坏造成的渗透率减小和颗粒运移形成的渗流衰减等因素共同引起的。(3)自行研制及应用了陷落柱渗流模型的物理试验系统和材料。配制了可进行渗透性调节的流固耦合试验相似材料,自行设计研制了陷落柱渗流模型的物理试验系统,为揭示采动影响下陷落柱渗流演化机理提供了新的试验材料、试验设备及相关方法。并通过该系统对不同渗透性的底板隐伏陷落柱模型进行了渗透性测试,获得了孔隙水压随水压力的变化规律:孔隙水压力随着扩散距离的增大而逐渐减小,且均服从双曲线衰减规律。(4)在考虑孔隙水压和应力场对岩体渗透率影响规律的基础上,建立了陷落柱渗流突变模型。基于有限差分法数值计算软件,对比模型试验结果确定了陷落柱渗流突变模型的计算参数,通过该数值模型研究了陷落柱的渗流突变过程中孔隙水压与时间、扩散距离、采动影响的关系,揭示了采动影响下底板隐伏陷落柱的突水机理。
[Abstract]:North China has always been an important coal base in China. North China coal field is threatened by karst strong aquifer and the coal resource is huge, and the mine Ordovician ash water damage is becoming more and more serious. As a special geological structure in North China, the collapse pillar is mostly developed in the Ordovician limestone, and it is easy to become a vertical water channel and the hydraulic connection between the floor of coal seam and the water of Ordovician ash will lead to a large-scale water inrush accident. At the same time, it is difficult to predict and prevent the collapse column water inrush with the characteristics of concealment, lag and sudden, so it is very important to study the seepage evolution law and water inrush mechanism under the influence of mining. In this paper, the collapse column is taken as the research object, and a series of studies are carried out on the percolation characteristics of the collapsing column filled with consolidation and mining state and the underlying collapse column under the condition of consolidation and mining by the method of theoretical analysis, laboratory test and numerical simulation. It has a certain guiding significance for the prevention and control of collapse column water hazard. (1) through the method of soil test consolidation, the sample of caved column filling material is prepared and the seepage characteristics of its consolidation state are tested. Under the condition of consolidation of caved column, the permeability of the caved column decreases with the increase of the consolidation pressure and the decrease of the initial moisture content, and the change of permeability shows the law of decreasing, increasing and decreasing in the process of total stress-strain, and the initial permeability of the settlement column decreases with the increase of the consolidation pressure and the decrease of the initial moisture content. There is an exponential function relationship between peak permeability and confining pressure. (2) the burst and lag of water inrush of collapse column are studied by permeability test of mining state of collapse column. The effects of seepage boundary and lateral confined axial pressure on permeability, start-up hydraulic gradient and particle loss quality are analyzed by the permeability test under mining state of caving column, and the influence of seepage boundary and lateral confined axial pressure on permeability, start-up hydraulic gradient and particle loss quality are analyzed. It is pointed out that the instability of the skeleton structure caused by the loss of large particles is the fundamental cause of the seepage catastrophe, and the significance of the 尾 factor of the non-Darcy flow is discussed based on the derivation of the non-Darcy flow. Based on the variation of stress field under the influence of mining, it is proposed that the lag of collapse column water inrush is due to the compaction of broken rock mass under the influence of mining. The decrease of permeability caused by secondary failure and the seepage attenuation caused by particle migration are all caused by the factors. (3) the physical test system and materials for the seepage model of collapse column are developed and applied. A similar material for fluid-solid coupling test was prepared to adjust permeability, and a physical test system for seepage model of collapse column was designed and developed, which provides a new experimental material for revealing the mechanism of seepage evolution of collapse column under the influence of mining. Test equipment and related methods. Through the system, the permeability of the subsurface collapse column model with different permeability is tested, and the variation law of pore water pressure with water pressure is obtained: the pore water pressure decreases gradually with the increase of diffusion distance. On the basis of considering the influence of pore water pressure and stress field on the permeability of rock mass, a sudden seepage model of collapse column is established. Based on the numerical calculation software of finite difference method, the calculation parameters of seepage catastrophe model of collapse column are determined by comparing the results of model test. The pore water pressure, time and diffusion distance during seepage catastrophe of collapse column are studied by this numerical model. The relation of mining effect reveals the water inrush mechanism of the underlying collapse column under the influence of mining.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TD74

【相似文献】