M Karami, R Bagherpur, D Raisi Gahrooee, L Faramarzi,
Volume 8, Issue 2 (11-2014)
Abstract
The Sabzkouh water conveyance tunnel, with a length of approximately 11 Km to transferred 90 million cubic meters of water per year from the Sabzkouh area to Choghakhor Dam, about 80 Km south of Shahrekord in Chahar Mahal-e Bakhtiari province is under study. Because of the long length of this tunnel and also low rate excavation by traditional tunneling methods, the Tunnel Boring Machine has been a priority. Due to limitations of TBMs in complex and unfavorable geological conditions, based on the precise study performed, the machine was selected. The geological features and the geomechanical properties of rock masses play an important role to selection of proper TBM. In this paper, by estimation of the most important geomechanical properties and geological conditions of the rock masses, with the interpretations of geotechnical logs and the laboratory test results combined with field observations, the rock mass of the Sabzkouh tunnel, based on the three common engineering systems of RMR, Q and GSI was classified. According to classification systems, the rock masses are divided into three geotechnical zones. Based on the uniaxial strength of intact rock, the properties of discontinuities, fault thickness and shear zones, the underground water level and the squeezing intensity the performance of hard rock TBMs was performed. Finally, double shield TBM for the excavation of Sabzkouh tunnel is proposed
Majid Taromi, Abbas Eftekhari, Jafar Khademi Hamidi, Mahdi Saeidi,
Volume 19, Issue 3 (12-2025)
Abstract
The Sabzkuh Water Conveyance System was planned as an inter-basin water transfer project in the Sabzkuh region of the Chaharmahal and Bakhtiari province, a tributary of the Karun River. Initially, the project included a diversion dam, an open canal, and a tunnel. However, in the initial feasibility studies, the potential environmental risks to the Choghakhor lagoon, ecosystem and regional groundwater resources were not given sufficient consideration.Only due to land acquisition problems in the Chahartagh forest area, the tunnel route was changed and the channel was also removed. Consequently, the project was scaled down to comprise only a diversion dam and a 11-kilometre-long tunnel. This is while the geological and environmental risks of the project area were not fully investigated in the selection of the final route. After 484 meters of excavation, the Solaqan fault was encountered and a sudden inrush of water with a flow rate of 100 liters per second and the liquefaction of the excavation front caused the TBM to get stuck. Subsequently, the drainage of water caused the drying of the Aloqareh spring and the depletion of the Shirkoshteh spring, and negative environmental and social consequences for the region. To release the TBM, two side galleries were constructed and grouting and drainage were carried out. Ultimately, the tunnel excavation operation was stopped due to the problems that arose. The challenges that arose in this project indicate the need for a comprehensive study and planning in the selection of the route and TBM, as well as environmental, economic and social assessments at all stages and examining their interaction with each other.
