Abstract
Loading tests are performed using various patterns of rock bolts in a 60cm diameter tunnel bored through 2.4m model ground to study the tunnel-reinforcing effect of rock bolts and establish an optimum pattern of rock bolts. Two forms of loading are implemented using side pressure coefficient of 1.0 and 0.5.
The model ground consists of low-strength sandy mortar with umaxial strength of about 1.0MPa and internal friction angle of about 25°. the rock bolts in length 10-40cm are placed at 8cm intervals with 12-48 bolts per a face.
Within the extent of the above-mentioned experiments, it is proved that the rock bolts pattern using large numbers of short bolt are effective on the condition that the total length of bolts are same.
