P-H-q evaluation system for risk assessment of water inrush in underground mining in North China coal field, based on rockbreaking theory and water-pressure transmission theory

Abstract

Risk assessment of water inrush from a coal seam floor is essential for safety in many coal mines. From the point of view of mechanics, such water inrush forms on the floor when the aquiclude breaks under the action of continuous water pressure within a certain period of time. Consequently, the water from the aquifer below the aquiclude gushes along the rupture surface into the goaf. In this study, to clarify the water inrush mechanism, a time-related function f(P, H, q) is developed (where P, H, and q are the aquifer water pressure, aquifuge thickness, and aquifer specific yield, respectively). Hence, the likelihood of water inrush can be determined. Data collected from 150 cases are used to determine the related parameter thresholds. The influence of P, H, and q on water inrush occurrence is analysed based on the time-related function. Finally, a P-H-q evaluation system is proposed and successfully applied. The P-H-q evaluation system not only facilitates realistic risk assessment for water inrush, but also elucidates the water inrush mechanism in underground mining. The results also provide a reference for evaluating the risk of water inrush in other coal fields.