Research On The Support Technology Of Deep Soft Rock Roadway With High Geo-Stress In Kaiyang Phosphorite Mine

With the increasing mining depth, large magnitude of terrestrial stress will result in a series of engineering disasters in underground mine, which will seriously affect the safety of miners and make the supporting costs and repairing costs of the tunnel to increase, Therefore. it is significant to support the tunnel by effective and legitimate methods. Rockbolt as one of the main supports in tunnel, plays an important role in reinforcing the rock, especially in the broken rock which are full of joints and cracks.In order to conduct the research on the support of deep tunnel of Maluping Mine, attatched to Guizhou Kailin Group. The preliminary research work includes the geological investigation, the measurement of the ground stress of the mining areas and the determination of mechanical properties of the four types of ore and rock. Based on information from the preliminary research stage, the parameters of rock mass have been used for designing tunnel supporting system. The length of the rockbolt and the inclination of bottom rockbolt were analyzed by Software-ANSYS. Results show that optimum support effect can appear when the length of rockbolt reaches to 3.0m and the inclination of bottom rockbolt is about 45°. At the same time, with the introduction of an ideal energy absorption bolt, the MIDAS/GTS finite element software is used to analyse various conditions of the ideal energy absorption bolt. According to the numerical simulation, the ideal energy absorption bolt not only can generate a initial deformation with the early deformation of rock, but also can provide a strong support resistance in the later period. Because of its obvious advantages in controlling the displacement of the surrounding rock, the integrity and the stability of the surrounding rock can be ensured. Meanwhile, it has a good supporting role in resisting the shear force.By placing the ideal energy absorption bolt in five locations where are in the tunnel crown, on both sides of the spandrels and the corners, and optimizing the rockbolt length and the angle of the floor bolt is proposed. Through mine field tests and dynamic monitoring of the surrounding rock deformation in the mine for three months, the convergence of two sides of the tunnel has decreased by 45.5%, and the convergence of roof and bottom plate has decreased by 45.6%, in which the amount of floor heave has decreased by 57.5% with the improved supporting scheme. New support bolts and method greatly improves the stability of the tunnel and it is proved the improved supporting scheme can provide an important reference on supporting in the deep tunnel.