Dam and power plant project of Lorestan Rudbar on the aerial parts of Rudbar River and about 100 km south of the town away Aligoodarz in Lorestan province, is under construction. The water conveyance system consists of the headrace tunnel, penstock tunnels and surge shafts. Bifurcation reason of Headrace Tunnel of powerhouse to two Penstock tunnels (where bifurcation), is that somewhere continuance the fault (CHAL HATAM fault), intercept the Headrace Tunnel, appropriate method for safekeeping and reduce eventual damage caused by fault movement, is transforming water through a pipe located in a open tunnel with enough space until accordance with the predicted displacement value from the expected shear stress in the tunnel and not harm the water supply pipes or damage is minimal. Thus The long headrace tunnel is bifurcated with the penstock tunnels. The main purpose of this research, is stability analysis and design of temporary support system for the stabilization of bifurcation area (BIF), using rock mass engineering 26 – 33 and Q = 0.09 – 0.5 is determined for bifurcation rock mass. In this research, the rock mass engineering stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600" 30) are installed on 1 m × 1 m grid spacing .
