Recently in Japan with the development of soil engineering, there have been an increasing number of constructions of fill-type high dams. Since the materials for the construction of these dams are permeable of water, the middle part of the dams is reinforced with impermeable core of clay. It happens sometimes that where clay is not available in the locality the construction of the dams will have to be given up. Once the dam is built the core is seldom repaired even if repair is required.
A fill-type dam faced with asphalt was devised in West Germany about 40 years ago on an upstream slope with successful result. This German work encouraged Japanese engineers to design the like, and in Japan today high dams are often constructed with asphalt facing on large scales. This is a new stabilization process of the slope under water, of which the design and work are described in detail in the present paper.