ABSTRACT
Steel pipe reinforced grouting method has been widely used to strengthen the tunnel face and prevent groundwater leakage during tunnel excavation. The conventional application requires sealant injection between the inserted pipe and ground to avoid backflow, which is a time-consuming sequence. Therefore, various injection procedures without sealing have recently been suggested to enhance efficiency. There are two main alternatives. One is simultaneous injection in segmented batches, and the other is multiple injection using the external packer. The pros and cons of each method were discussed in terms of construction duration and equipment. However, it has yet to be discussed how the injection procedure affects the grout diffusion range in the ground. This study aims to evaluate the grout diffusion range quantitatively by considering the practical grouting sequences. The grout viscosity was measured by laboratory testing. Then, the numerical modeling was structured using the commercial computational fluid dynamics software. Finally, the grout diffusion range affected by the injection procedure and ground conditions was evaluated by performing the numerical parametric study. The results showed that the injection method highly affected the grout diffusion range. Consequently, it is anticipated that the proper method of steel pipe reinforced grouting will be suggested.
