Conceptual drawing of shear box. Specimens were water sealed with high polymer sheets on their sides. Storage units were provided at the lower and upper ends of the fracture by installing water-sealing rubbers that withstand shear deformation. In the left figure, water flows from the inlet port to the discharging outlet. Water was first accumulated in the upper-end storage, then allowed to flow through the fracture, accumulated again at the lower-end storage, and allowed to flow again into the lower-end burette.