Widening and underground bonding of shields using the largest scale freezing method in Japan for sewer construction

摘要

The Senju District of Adachi Ward, Tokyo have been experienced flood caused by heavy rain frequent in recent years, as well as shortage of rainwater drainage capacity related to the increasing rainwater inflows to the sewers according to the rapid urbanization. Additionally, pump facilities constructed in the 1940s through 1960s have aged considerably. For these reasons, the Tokyo Metropolitan Government is proceeding in the Sumidagawa Sewer Trunk Line project which erect new rainwater trunk line and new pumping station to reduce flood damage, as well as to let us reconstruct the aged pumping stations.The Sumidagawa Sewer Trunk Line is T-shaped. In this construction project, ground freezing was used as an auxiliary method to widen the shield tunnel underground to connect large trunk sewers of 6.5-meter external diameter to existing smaller trunk sewers of 5.5-meter external diameter. The amount of ground freezing was 3,700 m~3 and this was the largest-scale freezing project in the history of Japanese sewerage construction.This paper describes the project's characteristics, including the process of freezing soil, the removal of pre-existing segments, the excavating of frozen soil, and the assembly of widening segments. It also reports on simulations and other initiatives conducted to achieve safe, efficient construction, and the use of Construction Information Modeling/Management, CIM.