伴随质量流失的胶结破碎岩体渗流失稳机理研究

The corrosion, washout and abrasion effects are the internal factors which result in particles running off and porosity increasing continuously in the seepage process of the cemented broken rock, and then triggering seepage instability. It is also an important reason that why water inrush happens at hidden collapse columns or faults. In this project, taking the cemented broken rock as the research object, based on the self-designed seepage testing system for broken rock, combining the theory and method of modern seepage mechanics, we conduct a systematic study on the process of mass loss for the cemented broken rock, as well as the seepage instability mechanism. The main contents are as follows: the characterization and determination of the rate of mass loss during seepage process of the cemented broken rock; the influence laws of the initial porosity of rock, pressure gradient, shearing strength and Talbol power exponents on mass loss and seepage instability; the establishment of the dynamic model of the non-Darcy flow seepage system for the cemented broken rock, considering the effect of mass loss by the corrosion, washout and abrasion effects; the design of the response of the corresponding dynamic model and the development of the program; the evolution and instability rules of the non-Darcy seepage field for the cemented broken rock; the instability condition of seepage field and the influence of the initial porosity of rock, pressure gradient, shearing strength and Talbol power exponents on the instability rules of seepage field. Research results of this project will provide significant references on studying on the methods of forecasting and preventing water inrush in coal mines.

胶结破碎岩体渗流过程中的溶蚀、冲蚀和磨蚀作用是导致岩体颗粒流失、孔隙度不断加大，进而引发渗流失稳的内在因素，是煤矿隐伏陷落柱、断层突水灾害事故发生的重要原因。本项研究以胶结破碎岩体为对象，借助于自行研发的破碎岩石渗透试验系统，结合现代渗流力学的理论与方法，对胶结破碎岩体渗流的质量流失过程及其渗流失稳机理进行系统研究，包括：胶结破碎岩体渗流过程中质量流失率的表征与测定，岩体抗剪强度、初始孔隙度、Talbol幂指数、压力梯度等因素对质量流失及渗流失稳的影响规律；考虑岩体质量流失效应（溶蚀、冲蚀和磨蚀作用）的胶结破碎岩体非Darcy渗流系统动力学模型的建立，以及相应的系统动力学响应算法设计及程序开发；胶结破碎岩体非Darcy渗流场演化及失稳规律的分析，渗流场失稳条件的建立，岩体抗剪强度、初始孔隙度、压力梯度等对渗流场演化及失稳规律的影响。研究成果可为煤矿突水事故的预测及防治方法研究提供重要参考。

在承压采煤过程中，随着工作面与陷落柱距离的减小，陷落柱及其附近岩体受到扰动后，应力场和渗流场发生变化，岩体裂隙网络和陷落柱内胶结破碎岩体孔隙结构发生显著变化，形成水渗流通道。胶结破碎岩体遇水产生细小颗粒并发生迁移和流失。在质量流失过程中，胶结破碎岩体的质量密度、孔隙度和渗透性参量随时间变化。当质量流失发展到一定阶段，胶结破碎岩体中形成区域性的贯通的管流通道，水流模式由渗流转变为管流，即渗流失稳，引发突水灾害。陷落柱突水本质上是质量流失引起胶结破碎岩体渗流失稳。. 本项目从质量流失引起水流模式由渗流到管流转变的视角，研究胶结破碎岩体的质量流失和渗流失稳行为，解释伴随质量流失的胶结破碎岩体渗流失稳机理，为含陷落柱的煤层开采存在的突水隐患提供新的解决思路。取得主要结果如下：.（1）胶结破碎岩体颗粒迁移和质量流失规律研究表明，质量流失是细小颗粒迁移的结果，受水流速度、Talbot指数、初始孔隙度和胶结剂含量的影响。质量流失率可表示为与初始孔隙度和时间相关的指数函数。.（2）胶结破碎岩体渗透性和渗流失稳规律研究表明，随时间的增加，渗透率单调减小，非Darcy流β因子的绝对值和加速度系数均匀增大。基于渗透性参量时变曲线，建立了黏土胶结、石膏胶结和水泥胶结的破碎岩石渗透率峰值、渗透率稳定值和衰减指数与Talbot指数、初始孔隙度和胶结剂含量之间的关系，提出了一种胶结破碎岩石渗透率模型，并设计了优化模型参量的遗传算法。同时构建了渗流失稳历时与压力梯度的对数函数关系。.（3）胶结破碎岩体非Darcy渗流场演化和失稳规律研究表明：陷落柱孔隙分布具有非均匀性，通过构建胶结破碎岩体渗流系统的动力学模型，设计系统响应算法，编制响应程序，计算得到了胶结剂含量、Talbot指数和初始孔隙度对岩体顶部渗流速度的影响。胶结破碎岩体中黏土含量越低，Talbot指数越大，初始孔隙度越大，顶部节点渗流速度越大，渗流稳定所需时间越长。