Knowledge of geological hazards plays an important role in the selection and installation of timely support system for underground structures. The Hamrov tunnel with an approximate length of 1294 meters in the main way of Sanandaj- Marivan is under construction. B More
Knowledge of geological hazards plays an important role in the selection and installation of timely support system for underground structures. The Hamrov tunnel with an approximate length of 1294 meters in the main way of Sanandaj- Marivan is under construction. Based on the geo-mechanical conditions of rock masses in the tunnel, it is necessary to investigate the possible geological hazards such as squeezing. In this study, using geological surveys and drilling of boreholes, the way of the tunnel been divided into different units and then the severity of squeezing in each section have been investigated. By comparing the different methods of squeezing evaluation, it was found that the empirical Hoek-Marinos method evaluate the minimum of squeezing and the Jethwa method evaluate the maximum of squeezing for the rock masses of the tunnel. The utmost squeezing potential is related to section of the tunnel where there is the alternation of sandy shale and limestone with shale. According to the survey, the Hamrov tunnel is divided into three sections: A (km 5293 to 5543) with squeezing extreme serious to serious, B (km 5543 to 5973) with squeezing severe to very low, and C (5973 to 6133 km) almost without risk of squeezing.
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In this paper, based on the results of experimental and analytical methods, crushed zone and gurpy rocks masses were identified as the squeezing sections. Then crushed zone and gurpy sections creep parameters at the Bruger model were obtained in the laboratory. Then cru More
In this paper, based on the results of experimental and analytical methods, crushed zone and gurpy rocks masses were identified as the squeezing sections. Then crushed zone and gurpy sections creep parameters at the Bruger model were obtained in the laboratory. Then crushed zone and gurpy sections modelling using the software Flac2D with burgers model for 30 days (long-term) were performed. Our numerical modelling results show the large displacements due to very low quality of the rock mass and high overburden in this sections of the tunnel. The results of the numerical modelling in the short-term, that TBM shield would be stuck in this section of tunnel. Also modeling this section in the long-term showed that stability and not seen failure of the segmental support system. But effect squeezing in two sections is not critical. Among the important phenomena that makes problem for tunneling, support and tunnel usage is squeezing which is a type of problems that takes place in weak rocks. Squeezing of the rock is time dependent large convergence, which occurs around the tunnel, and is essentially associated with creep caused by exceeding limiting shear strength. Squeezing is one of the important phenomena in the tunneling industry so drilling in the squeezing cases can be causing serious problems. Predicting the amount of displacement, radial strain, shear strain and plastic zone increment as functions of the squeezing degree resonator factors is one of the basic needs in drilling and tunnel maintenance. Squeezing is behavior that related with weak rock mass deformation and strength properties. This phenomenon is associated with large deformations and time dependent convergence during tunnel excavation. It takes place when a particular combination of induced stresses and material properties pushes some zones around the tunnel beyond the limiting shear stress at which creep starts. Deformation may terminate during construction or continue over a long period of time. West Kermanshah tunnel conveyance (WKTC), with about 8550 meters long and 6.884 m in diameter in the west of Iran is located in Kermanshah province. Mainly parts of the tunnel pass through weak rock make is including types of argillaceous, sandstone and shale, with high 570 meters overburden and will be probably under squeezing condition. Duets in this project the effect of experimental methods, analytical and semi-analytical are evaluated. Then critical section of the squeezing potential presented and finally numerical modelling of this phenomenon is done.
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on of the efficacious parameters in sketching elements is evaluating the geology dangers of underground excavations including squeezing and rock explosions in tunnels. the water transmission system was constructed from azad dam to degolan- ghorveh plain in o More
on of the efficacious parameters in sketching elements is evaluating the geology dangers of underground excavations including squeezing and rock explosions in tunnels. the water transmission system was constructed from azad dam to degolan- ghorveh plain in order to supply water to dehgolan - ghorveh plains. The squeezing and rock e xplosion phenomena were predicted considering the weekness of rock mass of the tunnel track, the overburden thickness and its settlement in the active zone. in the present research, the tunnel was initialy divided in to 5 zones by using the results of geological and borehole drillings. The squeezing and rock explosion in these 5 zones will be discussed later. The tunnel was situated in non squeezing and extreme squeezing zone. Regarding the previous investigations and also the emorical and semi empirical metheds. The tunnel had low potentidity in the view of rock explosion. finally, the Hook and Marinos and critical strain methods were compared via the Finite Element numerical Method using phase2 software. in order to investigate the occured replacement in the tunnel. based on the previous analysis , it was realized that the critical strain method had the most similarities with the numerical method. as for as the results of numerical and critical strain methods are matched, S3 and S5 zone can be the most unstable zones
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