Influence of a fault system on rock mass response to shaft excavation in soft sedimentary rock, Horonobe area, northern Japan

Tokiwa, Tetsuya; Tsusaka, Kimikazu; Ishii, Eiichi   ; Sanada, Hiroyuki; Tominaga, Eiji*; Hatsuyama, Yoshihiro*; Funaki, Hironori 

This paper focuses attention on stress field that produced fault system, and presents an example of the relationship between fault system and rock mass response to shaft excavation in soft sedimentary rocks in the Horonobe area, Japan. The directions determined by fault-slip analysis are close to the direction of maximum and minimum diameter reduction in the shaft. The results show that fault system can affects rock mass response to shaft excavation in soft rock and furthermore, and it is considered that the rock mass deformation was controlled by fault system. In addition, it is likely that we can assess and predict rock mass behavior by focusing on palaeo-stress field that produced fault system.