ABSTRACT
A cut slope failure happened in a diatom earth during the road construction at Takasu in Gifu Prefecture, Japan. An undisturbed sample was taken with the block sampling technique to investigate the cause of the failure. From the experimental findings, it is found that the soil structure can be easily destroyed by a small disturbance. Once the soil structure is destroyed, the sediments behave in a liquid manner due to a high water content. The trial field drainage tests were carried out to find out the optimum drainage pipe length for the countermeasure against slope instability. The excavation of the diatom earth slope has been successfully conducted with the proposed pattern of drainage pipes, stabilizing piles and surface replacement by the improved soil.
