A Computing Method for Sand Inrush Quantity through a Borehole in Longde Coal Mine

Boyang Zhang,Zhibin Lin

doi:10.1155/2018/4842939

Abstract

A quicksand disaster through a borehole occurred in Longde coal mine. A lot of aeolian sand, the volume of which is between 310,000 m3 and 380,000 m3, has submerged into the underground space in about 70.5 h. The volume flux of quicksand cannot be calculated accurately by the empirical method. Based on the method of fluid mechanics, an all-purpose computing method for quicksand disaster through a borehole was proposed. The result shows that the inrush volume of sand into underground space was between 310,000 m3 and 350,000 m3, which was consistent with the actual result. To apply and popularize this method, the impact laws of water yield properties of an aquifer on the volume flux were discussed. The all-purpose computing method can be suitably used for the volume flux calculation of quicksand disaster through the borehole.

Highlights

Water inrush is one of the most severe disasters during mining in China [1,2,3,4]. ere are vast deserts [5] in the ground and abundant coal resources underground [6] in Shanxi, Shaanxi, Inner Mongolia, Sinkiang, and Qinghai provinces in China. e hidden dangers of quicksand exist extensively in Western China during mining [7]
A lot of aeolian sand submerged into the underground space. e sand cleaning work lasted for almost one year, which caused serious economic losses and mining difficulties. e quicksand disasters caused by the borehole have been reported for many times in papers [15, 16], but this phenomenon has not been explained reasonably until now
It can be clearly seen that the borehole was not damaged in the whole process of quicksand disaster, and the drill pipe remained in the borehole all the time. e pro le of the quicksand process is shown in Figure 8: (1) ere is aeolian sand layer with a thickness of 30 m in the ground. e lithology is silty ne sand with a distinct thickness variation. e sand seam constitutes a uni ed aquifer together with the Sara Wusu group aquifer below

Summary

Introduction

Water inrush is one of the most severe disasters during mining in China [1,2,3,4]. ere are vast deserts [5] in the ground and abundant coal resources underground [6] in Shanxi, Shaanxi, Inner Mongolia, Sinkiang, and Qinghai provinces in China. e hidden dangers of quicksand exist extensively in Western China during mining [7]. Quicksand disaster happened occasionally with the water inrush, which have caused serious economic losses [8,9,10,11]. When the mining depth is shallow, the mininginduced fractures may go through the rock layers to the sand bed, or even to the ground surface In this situation, the water and sand can move to the goaf through the fractures and granular rock mass, which results in the quicksand disaster [14]. The quicksand disaster caused by a borehole from ground surface to underground. A lot of aeolian sand submerged into the underground space. e sand cleaning work lasted for almost one year, which caused serious economic losses and mining difficulties. e quicksand disasters caused by the borehole have been reported for many times in papers [15, 16], but this phenomenon has not been explained reasonably until now

Methods

Findings

Discussion

Conclusion