西部典型矿区风积沙含水层突水溃沙的起动条件与运移特征

Incipience condition and migration characteristics of aeolian-sand aquifer in a typical western mine

突水溃沙是西部矿井地质灾害的主要类型之一,为研究突水溃沙灾害的临界判据与水沙运移特征,以榆横矿区含水层风积沙为例,采用自主研发的水沙两相高速渗流试验设备,对4种不同粒径范围的风积沙进行了沙粒起动试验和溃沙试验,对混合风积沙进行了水沙两相高速渗流试验。得到了影响突水溃沙的2个临界速度条件:第一临界速度即沙粒起动速度,为0.38~1.26 mm/s;第二临界速度即溃沙临界速度,为2.48~3.54 mm/s。试验结果表明:体积膨胀是沙粒群起动的必要条件,突水溃沙灾害是起动的风积沙由量变逐步积累到质变的物理过程,分为3个阶段:(1)水携沙流动,(2)水沙混合流动,(3)沙携水流动。沙粒起动是水动能转变为沙动能的过程,溃沙时水沙混合流体运动表现为颗粒群浓度波传播的特征,沙粒间通过碰撞的形式传递能量。溃沙速率随初始水力梯度的增大呈指数增长,单位时间内溃沙量随水力梯度的增大而呈线性增加。

Water-sand inrush is one of the most common mine disasters in western China, which is adverse impact on safe-mining. This study aims to investigate the critical criterion of water-sand inrush occurrence and characteristics of water-sand migration. Water-sand transport experiments were conducted on four aeolian-sand samples with different particle sizes from an aquifer of Yuheng mine using high-velocity water-sand seepage equipment developed by the authors. The blended aeolian-sand was also measured using the aforementioned setup. Two critical velocities of water-sand inrush were identified. The first one is aeolian-sand incipience velocity ranging between 0.38-1.26 mm/s, and the second one is water-sand inrush critical flow rate with a range from 2.48 to 3.54 mm/s. The experimental data indicate that, one necessary condition of sand swarm startup is volume expansion. The process of water-sand inrush disaster is a physical process from quantitative changes to qualitative changes, which can be divided into three stages： 1） water brings sand, 2） water and sand get mixed and flow together and 3） sand brings water. The movement behavior of sand particles always manifest as concentration wave propagates. In this situation, the energy mainly transmits in the form of particle collision. When sand swarm starts, kinetic energy is transferred from water to sand. As the initial hydraulic gradient increases, the flow rate increases exponentially, and the amount of inrush-sand per unit time increases linearly.