裂隙内部溃砂运移特点及应力波动研究

EXPERIMENTAL INVESTIGATION ON MOVEMENT AND STRESS FLUCTUATION OF QUICKSAND INSIDE FISSURE

随着近年来煤炭资源的开采逐渐向西部地区发展，溃砂灾害的防治也越来越受到关注。本文通过自行设计的裂隙溃砂试验装置用两种石英砂颗粒以及3种天然砂样进行了溃砂试验，探究了溃砂的影响因素、运移特点以及裂隙内部应力变化规律。两种石英砂颗粒的试验表明，溃砂速度的大小主要取决于溃砂出口的宽度，总溃砂量取决于砂源区的砂量；受裂隙倾角的控制，裂隙通道的开启方式有局部空间扩展、局部空间移动、直接溃砂3类。3种天然砂样的试验得出，溃砂后干砂和水砂流对裂隙壁的作用力自溃砂入口至出口呈减小的趋势；根据应力变化规律将水砂流中颗粒的运移分两类：碰撞运移型，其裂隙内部应力存在波动；连续运移型，裂隙内部应力变化连续。3种天然干砂溃砂时对裂隙壁存在周期性作用力，粒径大的颗粒对裂隙壁的作用力、应力波动幅值及应力波动周期均较大，运用Matlab插值分析得出应力波动频率约为3.2～3.6Hz。水砂流溃砂时仅粒径最大的砂样仍存在应力波动，频率减小为2.7～3.5Hz，应力受粒径的控制增幅较小。试验获得了影响溃砂的主要因素以及砂体运移规律和应力波动现象，有助于进一步了解溃砂机理及裂隙内部应力变化情况，对溃砂灾害的防治起到一定的指导作用。

In recent years, coal mining gradually has transformed from eastern region to western region of China and the quicksand disaster had received increasing attention. This paper presents a series of experiments on the influencing factors of quicksand and the stress inside fissures caused by quicksand. Two different man-made quartz sand and other three natural sand samples are used in two quicksand test equipment set ups designed by authors. The experiment with two man-made quartz sand shows that the speed of quicksand mainly depends on the width of outlet. The total amount of quicksand mainly depends on the sand resource. Controlled by the fissure dip angle, the opening pattern of the quicksand passage can be divided in three types： the local space expanding, the local space moving and quicksand directly. The experiment with three natural sand samples show that stress decreases along the entrance to the outlet of fissure model regardless of dry sand or sand and water mixture flow. According to the stress variation, the transportation of water and sand mixture can be classified into two type： the collision transporting type, such as sand sample 1,which observed stress fluctuation; the continuous transporting type, such as sand sample 2 and sample 3,the stress changes continuously. All the dry quicksand of three natural sand samples can cause stress fluctuations to the fissure. The stress, the amplitude and period of fluctuation are larger when quicksand formed by larger particle. The stress fluctuation frequency of dry quicksand are about 3.2-3.6Hz by interpolation analysis with Matlab. For sand and water mixture flow, the stress fluctuations are only monitored in sand sample 1. When the frequency reduced to 2.7-3.5Hz and controlled by the particle size, the stress raises with little range. The outcomes can contribute to understanding the movement mechanism of quicksand and the stress dynamic inside fissure. It also has an important guiding to avoiding and preventing quicksand disaster.