STRATEGIES OF PASSING TBM UNDER ADVERSE GEOLOGICAL CONDITIONS IN GOLAB TUNNEL

چکیده مقاله

Underground excavations using full face tunnel boring machines (TBMs) are significantly increasing in Iran. Some factors such as geological conditions and machine specifications are essential in TBM advance rate. Golab water transfer tunnel (first lot) is located in Sanandaj-Sirjan structural zone. The tunnel passes through the variety of geological features such as faults, folds, joints and various metamorphic, sedimentary and igneous rocks. These phenomenons led to adverse geological conditions in the excavation process. Hence, many geological hazards such as collapse, mix face conditions, squeezing, and sticking ground were experienced during the tunneling. In this paper, the geological hazards that encountered on the tunnel face are introduced. Then, the mechanism of a collapse phenomenon occurred in the 02+500 km is discussed and relative solutions and experiences are mentioned. The experiences is recommended that before incurring this adverse conditions, the TBM operating parameters should be control with reduction in RPM and increase in thrust force. Moreover, two partial foams should be injected around and ahead the cutter head for more consolidation. Finally, self-excavation fiberglass rod is a fast and successful technique in collapse managements.