Mechanism of water inrush and quicksand movement induced by a borehole and measures for prevention and remediation

Abstract

In coal mining, a poorly sealed borehole is one of the channels that can lead to an inrush of water and quicksand movement, seriously compromising the safety of the coal mine. In this paper, we used the water inrush and quicksand incident at Longde Coal Mine as an example in order to investigate the mechanism of water inrush and quicksand movement induced by a borehole, as well as to develop measures for the prevention and remediation of such problems. Two sand funnel models and a water inrush outlet model are introduced from which to calculate the flow of the water and quicksand; a comparison of the two shows that the flow predicted by the water inrush outlet model is more consistent with observations from the accident than the sand funnel models. Based on the water inrush outlet model, the aquifer thickness and borehole diameter are the two key factors affecting the flow. The aquifer channel is inferred as tubular, with its diameter gradually decreasing from ground surface to underground, and a time-dependent surface subsidence model is constructed. Finally, we develop a prevention method, ''Prior to mining development, borehole should be investigated and plugged for prevention,'' and propose a remediation method, ''Changing the pipeline flow into fracture flow, followed by changing the fracture flow into pore flow, and finally grouting and plugging.''

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

“…As the boreholes were drilled through the sand bed and aquifer, if the boreholes are not sealed properly, water and sand inrush may occur. For example, a mixture of water and sand rushed into the roadway in Longde coal mine [4] when a borehole was drilled from the ground to the roadway ( Figure 3). As a result, many underground equipment and vehicles were buried, which led to an economic loss of tens of millions of dollars.…”

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

“…e velocity is calculated by the simultaneous Equations (6), (14), and (20), Equations (6), (15), and (20), Equations (6), (16), and (20), and Equations (17) and (20) when the sandwater mixture ow is, respectively, in laminar ow, e ectively smooth ow, transition region, and rough ow. e calculation results are shown in Table 7, from which it can be known that the sand-water mixture ow belongs to transition region, and the velocity and volume are 15.32 to 17.78 m/s and 310,000 to 350,000 m 3 , respectively.…”

“…2007. 09.008. ese prior studies are cited at relevant places within the text as references [16,37]. ( Supplementary Materials)…”

“…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.…”

Movement Law and Discriminant Method of Key Strata Breakage Based on Microseismic Monitoring

“…It seriously restricts the coal exploitation and the ecological protection, which has drawn much attention from the Chinese government [3]. High-intensity coal mines such as Daliuta Coal Mine, Ciyaowan Coal Mine [4], and Longde Coal Mine [5] have suffered from geological disasters such as roof collapse and water and sand inrush, resulting in many deaths and huge economic losses. In order to achieve safe production, it is very urgent to carry out research on rock mass failures and strata movement under high-intensity mining conditions.…”