破碎岩体变质量水沙二相渗流非线性动力学特性研究

The mining of western coal mines has gradually become the focus of coal resources development. Water and sediment seepage of fractured rock mass under the influence of large-scale high-intensity mining of thick aeolian sand, thin bedrock and shallow coal seam in Western China is likely to lead to serious water inrush and sand burst disasters. This paper systematically studies the coupling between the migration law of water and solid particles in the process of water and sediment seepage in the fractured rock mass and the variation characteristics of the fracture network structure of the fractured rock mass.The main research content includes the development of a test system for water-sand seepage in fractured rock mass, the deformation of solid medium in fractured rock mass under water-sand seepage and the variation of void network structure in fractured rock mass, and the time evolution of parameters such as mass change rate, seepage flow rate, sand burst rate, void rate and permeability of fractured rock mass under different seepage pressures and confining pressures. On this basis, a water-sediment two-phase seepage model describing the quality change of fractured rock mass is established, and a coupling algorithm is designed, which can comprehensively take the influence of various factors in to account. The criteria for stability of water-sediment seepage in fractured rock mass are determined by theoretical analysis, experimental test and numerical simulation. The occurrence mechanism of water inrush and sand burst under high-intensity mining in Ministry Coal Mine is helpful for improving the security of mining in West Coal Mine.

西部矿区厚风积沙、薄基岩、浅埋煤层受高强度大规模开采影响，采动覆岩破断致水沙渗流失稳，易造成重大突水溃沙灾害。本项目拟以水沙二相渗流引起破碎岩体质量变化诱发的耦合动力学系统运动失稳的视角展开研究。首先分析裂隙开度、水流速度等因素对风积沙输送特性的影响，研究高含沙水的启动压力梯度、流动特性变化规律。其次展开西部矿区采场典型浅埋覆岩组分、力学特性试验，结合离散元理论，建立围压作用下破碎岩体空隙网络特性模型。在此基础上，研究水沙渗流作用下破碎岩体固体介质变形、空隙网络架构变化规律；研究破碎岩体试样在不同渗流压力、围压条件下破碎岩体质量变化率、渗流量、溃沙量、空隙率和渗透率等参量随时间的演化特征，建立一种可描述破碎岩体质量变化的水沙二相渗流非线性动力学模型，并设计可综合考虑多种因素影响的耦合算法。最后建立西部采场数值模型，明确破碎岩体水沙渗流失稳的判据，揭示西部煤矿高强度开采下突水溃沙的发生机理。

西部矿区厚风积沙、薄基岩、浅埋煤层受高强度大规模开采影响，采动覆岩破断致水沙渗流失稳，易造成重大突水溃沙灾害。本项目围绕水-沙渗流作用下破碎岩体空隙网络结构演化时间效应、破碎岩体水-沙二相渗流非线性动力学特性等2个关键科学问题，通过现场检测、理论分析、室内试验和数值模拟相结合的综合研究方法，开展了水沙渗流时破碎岩体空隙网络特性演化、水沙耦合渗流非线性动力学特征以及渗流失稳判据攻关研究，取得了如下创新性成果：（1）明确了不同粒径级配情况下破碎岩体初始空隙网络特性与围压的关系，查明了破碎岩体碎屑运移导致的质量流失与初始孔隙率、粒径级配之间的规律以及破碎岩体空隙网络特性的变化特征，揭示了破碎岩体初始裂隙程度、范围的变化与破碎岩体质量由流失到增加的演化规律，建立了考虑围压作用的破碎岩体质量变化与空隙网络特性演化规律的数学物理模型。（2）明晰了水对骨架颗粒冲刷、潜蚀造成质量、渗透特性变化规律及渗流场时空演化规律，研究了高含沙水在破碎岩体中启动压力梯度、渗透特性变化规律，分析了采动破碎岩体的渗透特性、突水溃沙通道的形成机理以及非线性渗流的动力学特征，建立了采动破碎岩体水沙两相渗流模型和非达西变质量渗流模型，揭示了采动破碎岩体的非线性动力学渗流失稳规律。（3）建立了考虑各个参数（破碎颗粒粒径、破碎岩体体量、破碎岩体受力历程、水力坡度等）影响的破碎岩体水沙渗流数学模型，查明了不同级配含水沙体突涌的水动力学条件及水沙运移规律，建立了水沙运移规律及突变致灾的力学模型，揭示了突水溃沙灾害形成机理。（4）基于颗粒离散元（PFC）软件与Python 软件，建立了西部矿区薄基岩、厚风积沙、浅埋煤层的开采模型，研究采场中的破碎岩体水沙渗流行为，演化破碎岩体水沙渗流失稳过程，揭示了破碎岩体水-沙渗流致灾机理，建立了破碎岩体水沙渗流失稳判据。研究成果可为西部煤矿高强度开采下突水溃沙预测和防治提供理论支持与科学依据，应用价值高。