Establishment of the theoretical evaluation of grouting zone with consideration of seepage forces

Mikake, Shinichiro ; Nishigaki, Makoto*; Sato, Toshinori  

This paper states establishment of the theoretical evaluation of the grouting zone during excavation of tunnel deep underground tunnel under high water pressure condition. In this study, relationship between allowable pressure and active pressure in the grouting zone is examined by means of one dimensional theoretical solution of pressure due to seepage forces act on the cross-section of the tunnel. The results indicate that allowable pressure is lower than active pressure under conditions of low cohesion. Furthermore, relationship between reduction of hydraulic conductivity and active pressure in the grouting zone is examined and it is confirmed that active pressure increases as hydraulic conductivity decreases by grout injection. Therefore, an accurate evaluation of the grouting zone is very important for grouting design based on the results obtained.