ABSTRACT
Ground subsidence is one of the main concerns contractors and engineers have when undertaking tunnel excavation projects. Particularly vulnerable from subsidence are older as well as landmark buildings, which form major focal points in cities worldwide. It is with a view to protecting these structures during tunneling that a two-component injectable non-hardening Clay Sand system was envisaged 30 years ago in Japan. This paper will analyze the journey of this “Made in Japan” method from its inception, to industry acceptance and finally it’s widespread application in major tunneling projects. We will seek to show, via the analysis of real-world data, the multipurpose nature of this method for enabling excellent thrust stability during sharp curve excavation and for applications with EPB and Slurry TBMs alike. We will also show how this injectable Clay Sand material is evolving to meet the needs of bigger and more complex tunneling sites in the future.
