Research On Support Control Of Soft-rock Large Deformation In The Red Stratum Of Mid-yunnan Area

In recent years,with the further deepening of the construction of underground engineering in the western mountainous area and the prosperous urban area,the underground caverns under the soft rock stratum and the dense complex environment appear in a large number.The problems of large deformation and the impact on surrounding environment during tunnel construction are very prominent.That seriously threaten the safety of construction and restrict the progress of the project.Therefore,for the engineering environment,the geological environment,the complex surrounding environment of the water diversion project in Yunnan,how to construct in security and efficiently is the first problem in front of the engineering builders.It is of great significance for the design and construction of the relevant tunnels to carry out the key technology research on the supporting system of the large deformation tunnel in red beds in Central Yunnan.In this paper,based on the Chuxiong tunnel of central Yunnan diversion project,comprehensive investigation,theoretical analysis and numerical simulation are carried out to study the deformation characteristics and support system of the support of red-bed soft rock tunnel in the Middle Yunnan red layer.The following research results have been formed:(1)The engineering geological characteristics of red rock soft rock tunnel in Central Yunnan and the problems of large deformation caused by soft rock are expounded.According to the classification of the large deformation of the soft rock,the displacement of the red-bed soft rock tunnel in Central Yunnan is discussed.On this basis,the safety control excavation with different extrusion deformation degree is established.(2)According to the analysis of the mechanical behavior characteristics and deformation laws of the surrounding rock support structure under the original design conditions,the rationality of the design parameters of the original support is judged aiming at the tunnel with slight and medium extrusion deformation under the strong supporting system.The key supporting parameters of tunnels with slight and medium deformation are optimized.(3)By means of numerical simulation,the typical section of tunnel under severe extrusion deformation is analyzed,and the rationality of its original support parameter design is judged.The tunnel under the condition of strong support and yielding support are optimized and analyzed.The structural safety and construction economy are compared under different support conditions,and the choice of yielding support is more appropriate..