Abstract
In this study, the X5 KCC in Shiquan Coal Mine was investigated by means of controlled source audio magnetotelluric exploration and borehole television. In this way, the subsection geological structure of the KCC was obtained. Next, the geological and electrical characteristics of each part were analyzed, and it is concluded that the development status of the mud part under coal seam floor is the key part to judging whether water inrush will occur during working face recovery under aquifer pressure. Furthermore, the mineral compositions of purplish-red mudstone and lime mudstone were obtained by performing an X-ray diffraction experiment on the KCC interstitial materials. On this basis, the water insulation properties of the mud part were qualitatively evaluated. Finally, the tensile strength of the mud part was obtained by the Brazilian splitting method, and the water insulation ability of the mud part at the periods when the tunneling roadway and the working face passed the KCC was calculated, respectively. The research results boast guiding significance for safe recovery of the working face passing KCCs under aquifer pressure.
Highlights
Karst collapse columns (KCCs) are a kind of special depression fault gradually formed in a long geological period under the condition of soluble rock strata and good groundwater dynamics [1]
From the perspective of water inrush mechanism, a KCC can be divided into four parts, namely, the lower enrockment part, the middle mud part, the upper clast part, and the surrounding rock fracture part [12], and different parts correspond to varying fabric characteristics, water contents, and water conduction properties
The macroscopic subsection structure and water conduction properties of a KCC are the geological basis to determine whether water inrush will occur when the KCC is exposed in the process of mining
Summary
Karst collapse columns (KCCs) are a kind of special depression fault gradually formed in a long geological period under the condition of soluble rock strata and good groundwater dynamics [1]. The macroscopic subsection structure and water conduction (insulation) properties of a KCC are the geological basis to determine whether water inrush will occur when the KCC is exposed in the process of mining. As the main method to explore KCCs from the perspective of geological structure, mainly solves the problem of KCC identification [21,22,23,24,25]. Geofluids sounding method, which explores KCCs from the perspective of hydrogeology, mainly solves the problem of KCC water content [26,27,28]. These geophysical exploration methods interpret KCCs as a whole, without fully considering the characteristics of their subpart geological structure. The research results provide geological basis for safe mining under aquifer pressure in the 30107 working face
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