Experiment on Seepage Property and Sand Inrush Criterion for Granular Rock Mass

Kai Zhang,Boyang Zhang,Haibo Bai,Dan Ma,Jiangfeng Liu

doi:10.1155/2017/9352618

Kai Zhang, Boyang Zhang + Show 3 more

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https://doi.org/10.1155/2017/9352618

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Abstract

Water and sand inrush is one of the most serious threats in some shallow coal mines in China. In order to understand the process of sand inrush, experiments were performed to obtain the criterion for sand inrush. First, seepage tests were carried out to study the hydraulic properties of granular sandstone. The results indicate that seepage velocity has a linear relation with the porosity and particle-size distribution parameter. Then, sand inrush tests were conducted to investigate the critical conditions for sand inrush occurrence. It is determined that the sand inrush zone can be clearly distinguished based on the values of porosity and particle-size distribution parameter. Additionally, sand inrush tended to happen in the conditions of high porosity, high seepage velocity, and large particle-size distribution parameter. Further, general principles for preventing the water and sand inrush were proposed, such as reducing the porosity, improving the pore structure, and decreasing the seepage velocity. The proposed principles have been successfully used in situ to control the water and sand inrush.

Highlights

IntroductionThe typical characteristics of the coal mines in this area are the shallow mining depth, aeolian sand bed near the ground surface, and thick coal seams
The coal field in Shaanxi province is one of the major coal bases in China
Compared with the coal mines with deep mining depth, the overburden strata movement and the distribution of the mining induced fractures are quite different in the coal mines in Shaanxi coal field

Summary

Introduction

The typical characteristics of the coal mines in this area are the shallow mining depth, aeolian sand bed near the ground surface, and thick coal seams. When the mining depth is shallow (Figure 1(b)), the mining induced fractures may go through the rock layers to the sand bed, or even to the ground surface (Figure 2). In this situation, water and sand may move through the fractures and granular rock mass to the goaf and affect mining safety. The mining activity had to be stopped for days until the sand was cleared

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