Reasonable Shallow Depth Of The Station And Its Surrounding Rock Stability Analysis To Determine

The selection of the station and tunnel depth, and support patterns are urgent problems that need to be solved during the process of building the subway. Based on domestic and international subway construction in the city, this paper introduced research of the principle of mining method and techniques of construction, buried depth of the traditional boundaries of standard chamber, the method of determine the depth based on key interface, the traditional principle of tunnel surrounding rock, etc., and used numerical methods to simulate the impact of Dunhua Road rail station and the adjacent rock tunnel excavation on the geological conditions, in order to find out the stratification of stress distribution under the impact of law and the depth of support The mechanism of the stability of surrounding rock for the purpose of better service for subway construction.(1)This paper used finite difference software FLAC to establish Dunhua Road and near the tunnel's three-dimensional simulation model to simulate tower-style subway station during Shallow, and further analyze stress and displacement of surrounding rock, this paper preliminary obtained the variation of the stress surrounding the tunnel depending on the depth for the geological conditions of Qingdao, to provide theoretical support for determining the depth of similar underground projects .(2)For the similar geological conditions in Qingdao which the stratum is featured by upper soft and under hard, this paper come to the principles of determining the depth of the tunnel and underground caverns depending on the key interface, which facilitates fast and accurate selection of the best depth in practical engineering. Using this method, the depth of Dunhua Road station is determined at about 14.5 meters, that is, about 2.5 meters lower than the less weathered granite interface.(3)After study of excavation and stress of re-division, it is found that change of rock stress is not monotonous, lifting off the stress transfer to the surrounding rock within a ring surrounding area. This area is called pressure ring, shows the nature of the structure in the surrounding rock, more obvious by the stress state. When the shallow depth and the rock strength is high, small changes exists in rock stress, which showed a common surface of loose rock; as the depth increases, stress concentration will become increasingly apparent, confined within the surrounding ring thickness gradually increased; when the depth or tectonic stress was great, excavation of rock may induce burst. Under normal circumstances bearing ring will not be damaged, but when with a great stress, the pressure ring will be unstable, new pressure ring will be formatted in outer surrounding.