Construction technique of groundwater-preventing piston in Karst flow collapse column

Taking a large inrush disaster controlling engineering from Dongpang coal mine as an example,the col-lapse column space structure characteristic and hydrogeologic condition are analyzed,and two stages controlling projects of rapid grouting and construction of groundwater-preventing piston are presented.This paper based on spatial properties and geological conolitions of collapse column introduces systemically technique and method of groundwater-preventing piston construction,technical process,engineering method,as well as quantity test and evaluation technique.In order to ensure the drill rig work according to designed parameters,adopt advanced direc-tional screw-rod drilling and drill-pipe logging.