Thermal Effects in Large-Sized Diaphragm Wall

Kawasaki Island was built at the center of Tokyo Bay as a ventilation facility for the Trans Tokyo Bay Highway. The centerpiece of this island is a cylindrical cast-in-place diaphragm wall, which served as a cofferdam during construction of the permanent structure. A state-of-the-art instrumentation system is used to monitor the behavior of the man-made island and was used to ensure safety during the long construction period. This paper discusses the correlation between the stress data recorded by the instrumentation system and the changes of the thermal conducting environment around the wall. It describes the concrete crack patterns observed at the inside face of the diaphragm wall, and suggests the existence of a critical wall thickness beyond which excessive thermal cracking in concrete would be expected to occur. Experience gained in integrating the design, instrumentation, and construction of a large-sized diaphragm wall is presented.