Jinchuan Deep Tunnel Stability And Support Technology

Accompany with construction and development of Jinchuan No.2 Mining District, the research of tunnel stability and tunnel supporting have never break off. Domestic and international research institution compare Jinchuan Ming District to museum of rock mechanics, Therefore, rock condition in Jinchuan Ming District is very complicated, so it is a big problem. As mining goes deeper, the tunnel deformation and failure become more and more serious. It is urgent to make clear mechanism of deep tunnel deformation and failure and do research on deep tunnel supporting. The paper discusses some research on these problem.Ground stress distribution regulation in Jinchuan No.2 Mining District: direction of maximum main stressis near north east 30°~40°, stress axis of stress is near horizontal, with horizontal stress predominance. Ground stress, v/hich in earth's surface is small, increase with depth increasing, and its increase rate is about 4.5Mpa/100m. Now, mining depth of Jinchuan No.2 Mining District is 600~700m, it will reach 900m in 850 level, which belongs to deep mining. The maximum horizontal main stress will change from 30.5Mpa to 45.7Mpa and vertical stress change from 15.4Mpa to 23.2Mpa. Addition to dynamic environment of mining, ground stress in deep tunnel rock may reach 50Mpa, which belong to high ground stress area. fracture-flimsy rock formed because of frequent incising week discontinuity (fault surface, lamination plane and nodal section), a large part of which is fracturing structure, strength of which is high, but the whole strength of rock is low. Under this high ground pressure, the rock express obvious time effect-creep. In customs, this kind of rock is called fracturing, expansive and creeprock.According to research, the reason for the deformation and failure of deep tunnel can be get: nodal section and fissure in deep tunnel rock up growth, a large part of the rock belong to fracturing structure. Because of high level ground stress and dynamic environment of mining, surrounding rock take on fracturing, expansive and creep character. Deformation includes the slip, dislocation along structural surfaceof fracturing rock , extension of fissure and etc. Compared it with plastoelastic deformation of continuous deformation of particle before intensity peak value, its deformation is much bigger. But people haven't catch the form, develop and scale of loose circle in main tunnel surrounding rock, and some other problems, such as relevant supporting theories can't be applied successfully, and the supporting measure which being taken now, and construction quality is also unstable.This thesis thinks it is more reasonable to proceeding the design of tunnel supporting according to the theories of big deformation loose circle, and puts forward some proposals about design, construction and monitoring.