突水溃沙灾害是困扰我国西部多个大型煤炭基地安全生产的棘手问题。本文采用理论分析与室内模拟试验相结合的方法，从沙粒受力运动角度出发，对沙粒流失过程中含水层的渗透性表现进行了探索，以期为突水溃沙的起动机制以及溃沙机理提供理论与试验依据，进而指导溃沙灾害的防治，达到资源安全开发，生态环境保护的目的。由此开展了一系列的工作：

根据含水层内松散堆积沙粒的结构，引入“隐蔽度”这一参数用作沙粒状态描述，对沙粒的起动行为进行理论分析，给出沙粒的理论起动水流速度，并对特殊堆积形态下的沙粒起动行为进行了分析，将水流速度作为引起沙粒起动的根本因素。设计了水沙起动试验来对沙粒的起动临界条件进行探讨。在测试了五组不同配比试样在三级压缩位移下的起动流速之后，通过数据分析给出了起动流速关于Talbol级数n与孔隙度的关系式，给出了试验的起动流速范围。

为探究突水溃沙过程中含水层内部渗透性变化，利用改进后的变质量渗透试验系统，通过改变初始孔隙度、初始水压梯度、沙粒径等条件，开展变质量渗透试验，定量分析了其过程中的水流参数、沙流失量、孔隙度变化等参数。沙粒流失过程中，试样的水压梯度与流量由初始值开始缓慢变化，随之突变，并最终稳定。同时证明初始水压梯度越大、初始孔隙度越大、沙粒越小，发生突水溃沙灾害的可能性越大。而随水力条件减弱，初始孔隙度对于整个过程中渗透性的影响在增强。

考虑了含水层内部渗透性与裂隙通道对于突水溃沙的影响，设计了可以实现变通道尺寸的水沙涌出试验系统，基于稳态渗透法开展了不同孔径通道的水沙溃出试验。获得了不同初始水压梯度下的水、沙流量，并采用敏感性参数法对渗透过程的水力敏感性进行了分析。随初始水压梯度的增大，各通道尺寸下水力敏感曲线峰值逐渐增大，峰值时刻也会随通道尺寸的增大而提前，其提前表现随初始水压梯度的减小更加明显。

在前面试验的基础上，综合运用毛细管模型假设和模型渗透率方程，考虑内部沙粒流失引起的含水层结构孔隙度和渗透率变化，引入毛细管渗透率方程、迂曲度、比表面积等内容，通过试验数据为参照对模型进行修正，建立了含水层动态渗透模型。对沙粒起动试验所得的临界流速结果代入模型方程进行求解，针对不同初始水压梯度下的沙起动条件以孔隙度条件形式给出了解，并利用数学分析给出了临界孔隙度所在的区间，可为实际工程中含水层改造提供指标选取的参考。

Water and sand inrush is a thorny problem that plagues the safety production of many large coal bases in western my country. In this paper, the method of combining theoretical analysis and laboratory simulation test is used to explore the permeability performance of the aquifer in the process of sand loss from the point of view of the force movement of sand particles, in order to explore the starting mechanism of water inrush and sand inrush and the sand inrush. The mechanism provides theoretical and experimental basis, and then guides the prevention and control of sand breaking disasters, so as to achieve the purpose of safe resource development and ecological environmental protection. A series of work has been carried out from this:

According to the structure of the loosely accumulated sand particles in the aquifer, the parameter "Hiddenness" is introduced to describe the state of the sand particles, the starting behavior of the sand particles is theoretically analyzed, and the theoretical starting water velocity of the sand particles is given, and The starting behavior of sand particles under special accumulation forms is analyzed, and the flow velocity is regarded as the fundamental factor that causes sand particles to start. A water-sand start-up test is designed to discuss the critical conditions for the start-up of sand particles. After testing the starting flow velocity of five groups of samples with different proportions under the three-stage compression displacement, the relationship between the starting flow velocity and the Talbol series n and porosity is given through data analysis, and the starting flow velocity range of the test is given.

In order to explore the changes in the internal permeability of the aquifer during the water inrush and sand collapse, the improved variable mass permeability test system was used to carry out variable mass permeability tests by changing the initial porosity, initial water pressure gradient, sand particle size and other conditions , Quantitative analysis of water flow parameters, sand loss, porosity changes and other parameters in the process. In the process of sand loss, the water pressure gradient and flow rate of the sample slowly change from the initial value, followed by sudden changes, and finally stabilized. At the same time, it is proved that the greater the initial water pressure gradient, the greater the initial porosity, and the smaller the sand particles, the greater the possibility of water inrush and sand collapse. With the weakening of hydraulic conditions, the influence of initial porosity on permeability in the whole process increases.

Considering the influence of the internal permeability of the aquifer and the crack channel on the water and sand burst, the water and sand gushing test system that can realize the variable channel size is designed, and the water and sand burst with different aperture channels is carried out based on the steady state permeability method. Out of the test. The water and sand flows under different initial water pressure gradients are obtained, and the sensitivity parameter method is used to analyze the hydraulic sensitivity of the seepage process. With the increase of the initial water pressure gradient, the peak value of the hydraulic sensitivity curve for each channel size gradually increases, and the peak time will also advance with the increase of the channel size, and its early performance becomes more obvious with the decrease of the initial water pressure gradient.

On the basis of the previous experiments, comprehensively use the capillary model assumptions and model permeability equations, consider the changes in the porosity and permeability of the aquifer structure caused by the loss of internal sand particles, and introduce the capillary permeability equation, tortuosity, specific surface area, etc. Contents, the model was revised based on the test data, and the dynamic permeability model of the aquifer was established. Substituting the critical flow velocity results obtained from the sand initiation test into the model equation to solve the problem, the sand initiation conditions under different initial water pressure gradients are understood in the form of porosity conditions, and the interval where the critical porosity is located is given by mathematical analysis. It can provide a reference for index selection in the actual process of aquifer reformation.