An Index of Aquiclude Destabilization for Mining-Induced Roof Water Inrush Forecasting: A Case Study

Gangwei Fan,Chengguo Zhang,Qizhen Li,Mingwei Chen,Shizhong Zhang,Dongsheng Zhang

doi:10.3390/w11102170

Gangwei Fan, Chengguo Zhang + Show 4 more

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https://doi.org/10.3390/w11102170

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Journal: Water	Publication Date: Oct 18, 2019
Citations: 8	License type: CC BY 4.0

Affiliation: China University of Mining and Technology, UNSW Sydney

Abstract

Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case study of roof water inrush accidents in Cuimu coal mine, China. The relation between roof water inrush and water level variation in the aquifer, and the characteristics of aquiclude deformation, were studied in this assessment. Using the developed assessment criteria, the likelihood of roof water inrush was categorized into different risk levels, which were followed by a proposal for roof water inrush control measures. The main findings of this study are: a) in Cuimu coal mine, the waterbody in the bed separation between the upper aquifer and the aquiclude directly causes the inrush, and inrush occurs after the water level declines in the aquifer; b) tension-induced horizontal strains of aquiclude can be regarded as the index to evaluate the stability of aquiclude affected by underground coal mining—roof water inrush occurs when the maximum horizontal strain reaches a threshold of 10mm/m—c) based on the critical mining height for aquiclude instability, and the different thicknesses of barrier layers, high-risk zones are identified and inrush controls are proposed.

Highlights

Mine roof water inrush has been identified as one of the most critical threats to mining safety and production in China
An obvious increase in water level occurred on 1 July, because by 196.8 m as the longwall retreated
An obvious increase in water level occurred on 1 July, because thethe surface borehole waswas blocked off,off, duedue to mining-induced strata movement

Summary

Introduction

Mine roof water inrush has been identified as one of the most critical threats to mining safety and production in China. With characteristics such as burstiness, instantaneity and destructiveness, water inrush can trigger various degrees of catastrophe, ranging from submerging the working face, to mine flooding and casualties. These accidents have resulted in tremendous losses to workforce safety and state economy [1,2]. Coal extraction can result in overburden strata deformation, breakage and collapse, accompanied by mining-induced fractures, developing upwards.

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