Research On The Control Technique On The Large Deformation Of The Water Tunnel Of The SE'ER GU Hydropower Station

The tunnel soft rock large deformation is a tough problem in the prevention of tunnel disasters. It has never been properly solved, no matter in the mining, hydraulic engineering or the communication industry. Since the 1960s when the soft rock large deformation was been put forward as a difficult problem, experts and scholars from different countries have been doing research in that area, and the soft rock engineering mechanics has been continuously developing. In the practical engineering projects, many methods to control the large deformation have come up and brought about great achievements.Due to various causes of large deformation and various mechanisms in that problem, the controlling method of the engineering has high pertinence. This thesis aims to study the control of large deformation of the water tunnel of the SE'ER GU hydropower station. It is based on the studies on the characteristics, causes and control mechanisms of the large deformation. The thesis analyzes the causes in according to the features of large deformation of the water tunnel of the SE'ER GU hydropower station, studies the characteristics and causes to find the key to solve the problem, and comes up with control methods for the general mechanism of the large deformation of the water tunnel.The third chapter of this thesis discusses the stability control theory of the soft rock tunnel large deformation, aiming to find the control method to deal with tunnel large deformation. This chapter mainly analyzes the relationship among the supporting structure, the adjoining rock stability, and the calculating theory of the soft rock large deformation. It does a detailed comparative study on the functions of different types of support structures to control the deformation.The project of the construction of this tunnel is to first dig the upper step until the whole line is made through, and then dig the lower step. In accordance with the characteristics of the tunnel, rock bolt and the steel support are adopted as the main types of support to control the deformation. Chapter Four makes a numerical simulation on the method of the upper step. Aiming at controlling the deformation, this part makes different choices on steel support and the line spaces and length of the rock bolt.According to the change of the two parameters, it takes the way of, orthogonal combination to calculate and compare and finally works out a relatively appropriate support structure ensuring the safety of excavation on the upper fracture of the tunnel. Measures to repair the formal large deformation are brought forward. To prevent the lower-half fracture from large deformation during the digging, and to ensure the safety of the second-time lining of the upper-half fracture, Chapter Five does numerical simulation again on the excavation of the lower step, in order to work out the right method of the digging and support to control the large deformation of the whole tunnel.