Rock Engineering

[3305-12-08] Investigation and consideration on yielding supports used in mountain tunnelling

○Takuya Tani¹, Kazuo Sakai¹, Tomoyuki Aoki¹ (1. Taisei Corporation)

Chairman: Yoshiaki Fujii (Hokkaido university)

Keywords:yielding support, mountain tunnel, large overburden

In mountain tunnelling where large deformation is expected to occur, there is a method that applies voids or yielding supports to allow for large tunnel deformation to control it by reducing and restricting the failure of support members. In European countries in particular, effective tunnel construction has been lately carried out by implementing newly developed yielding supports for railway tunnels under large overburden.
While we have been developing our own support materials to be adopted at the tunnels under large overburden, a sample of yielding concrete material (hiDCon) developed in Switzerland was imported. A series of experiments were then carried out to verify the yielding mechanism and basic performance of the hiDCon.
In this paper, the following two topics are reported:
Knowledge learned on the yielding mechanism of the hiDCon and the size effect that is observed in the load-deformation relationships; and
Summary of adoption status of yielding supports including the hiDCon and its construction status observed in the site visit.