Reinforcing Effect of FRP Multi-step Grouting Method for NATM Tunnel by Back Analysis Method

摘要

A fiber glass reinforced plastic (FRP) pipe has been newly developed for grouted-reinforcing membersrnand widely used in the tunnel excavation in Korea. The multi-step grouting method using FRP pipe,rnhave the advantage in the reinforcing effect and the handling of reinforcing members, compared torntypical reinforcing method such as fore-poling and steel pipe reinforced grouting methods. Generally,rnwhen excavate tunnel in soft ground, it is grouted through the steel or FRP pipe to reduce muchrndisplacement of tunnel. However, in practice it is difficult to evaluate correct design parameter inrngrouted zone. In this paper, based on the measured data of tunnel 3-dimensional back analyses werernemployed to evaluate design parameter of grouted zone. From the back analysis results, it couldrnconfirm reinforcing effect by increment of elastic modulus in grouted zone and decide the space andrnlength of FRP reinforcing member at the other adjoined tunnel also.