Laboratory test on unsaturated hydraulic conductivity of densely compacted Gaomiaozi Bentonite under confined conditions

In deep geological disposal for high-level radioactive waste,the engineering barrier made by densely compacted bentonite is used to prevent the groundwater infiltrating and the radioactive waste diffusing.It is necessary to study the unsaturated hydraulic conductivity of densely compacted bentonite under the confined conditions.The instantaneous profile method is employed to study the unsaturated hydraulic permeability of densely compacted Gaomiaozi bentonite under the confined conditions.Results show that the coefficient of unsaturated hydraulic conductivity of Gaomiaozi bentonite is between 1.13×10-13 and 8.41×10-15 m/s,and it does not vary linearly with the soil suction.The coefficient of hydraulic permeability is the lowest at the suction of 68 MPa.And when the suction is higher than 68 MPa,the hydraulic conductivity increases with the increase of the suction;but it is reverse when the suction is below 68 MPa.