ABSTRACT
Field measurements for the existing tunnel were carried out in section 4 and 5 shown in Figure 1(a). Strain of lining, using the space above the protector by attaching strain gauge shown in Figure 1(b), and convergence and crown settlement of four measurement lines were measured. Stresses of steel arched rib and shotcrete and axial force of rock bolts were measured in enlarged tunnel shown in Figure 1(c).
