Development of the water-conducting fracture zone in longwall top-coal caving mining with super-large mining height and weak cemented overburden

Abstract This study investigates the height evolution of the water-conducting fracture zone (WCFZ) under super-high mining conditions in the 1101 longwall face of Zhundong No. 2 Mine. Based on 28 measured datasets, a multivariate nonlinear regression model is proposed, outperforming traditional empirical formulas in accuracy. Numerical simulations reveal four developmental stages of the WCFZ: initial acceleration (0–180 m), deceleration (180–270 m), renewed acceleration (270–420 m), and stabiliz