Height calculation of water conducted fracture zone in thick and extra-thick coal seams under the condi-tions of fully mechanized top coal caving mining
XU Bin
QI Rongrong
DONG Shuning
DAI Zhenxue
YIN Shangxian
LI Shuxia
ZHONG Cen
MIAO Yu
Abstract：The theoretical calculation of the height development of water conducting fracture zones under fully mechanized top coal caving conditions is crucial for the prevention and control of water hazard in coal mine roofs.With the advancement of thick top coal caving technology,existed empirical formulas cannot fully meet the prediction of water conducting fracture zone height in thick and extra-thick coal layers.Based on the measured values of the height of water conducting fracture zones in 185 sets of thick and extra-thick coal seams in China,according to the lithology of the overlying rock,the data is divided into three categories:hard,medium hard,and weak.Four mathematical models,including guideline-like formula,linear regression,quadratic regression,and DoseResp function,are used to fit and analyze the data.The model reliability is analyzed using the goodness of fit R2.Under hard overburden conditions,the goodness-of-fit is DoseResp model>quadratic regression model=linear regression model>guideline-like model.Under medium hard and weak overburden conditions,the performance of the goodness-of-fit is DoseResp model>quadratic regres-sion model>linear regression model>guideline-like model.Furthermore,the mean absolute percentage error(MAPE)method is adopted to compare the reliability of the newly fitted formulas with those specified in the Guidelines for Coal Pillar Layout and Min-ing Under Buildings.Water Bodies,Railways and Main Shafts/Tunnels(hereinafter referred to as the Guidelines).For hard overbur-den,the accuracy of the four new fitted formulas was higher than that of the existing formulas in the Guidelines;for medium hard overburden conditions,the accuracy of the four new fitted formulas was better than that of the existing formulas in the Guidelines,and the DoseResp model performed the best.For weak overburden conditions,the guideline-like formulas and the DoseResp model are better than the existing formulas in the Guidelines.Applying the newly fitted formulas to specific mines,the DoseResp function has good applicability in predicting the height development of water conducting fracture zones in thick and extra-thick different over-burden rocks(hard,medium hard and weak),followed by the guideline-like model,and both predictions are better than the formulas in the Guidelines.
Keywords：fully mechanized top coal caving miningthick and extra thick coal seamwater conducted fracture zoneroof water hazard prevention and controlempirical formulaDoseResp function
Publication Date：2025-12-20
Online Publishing Date：2025-12-29(First online date of this platform, not the publication date of the document)
Pages：9( 182-190 )