Mass-loss effects on the non-Darcy seepage characteristics of broken rock mass with different clay contents

Abstract A seepage testing system was designed and a series of experiments on broken rock conducted using different original porosity conditions clay contents. The mass-loss process the change in water flow velocity were investigated. After test, non-Darcy characteristics tested through step-by-step pressure-reduced test. experimental results show that evolution during inrush could be divided into four stages: acceleration, stable with slight fluctuations, reacceleration, stable. lost-mass positively correlated contents negatively porosity. By introducing equation Kozeny-Carman liquid limit index which characterises effective particle size, prediction model permeability coefficient built. Six models verified against results. critical from Darcy to Forchheimer number also established. provide an important reference for understanding mechanisms, adopting control measures events, calculating influx tunnels.