Discrete Element Analysis Of The Large-span Tunnel In The Jointed Rock Mass

Discrete element method is a kind of geotechnical engineering numericalsimulation method which began to appear in the1970s, its purpose is to make thesimulation analysis more suitable for joint rock or discrete block rock in geotechnicalengineering construction process, and explore the effect on the mechanical response andstability of the surrounding rock during the geotechnical engineering construction. Thismethod was first used to simulate the gradual failure process of rock slope, then after alot of exploration it expanded to apply to slope engineering, mining engineering andunderground structure.With the advancement of domestic urbanization construction, undergroundengineering, such as urban subway, had been greatly developed, and the stability ofsurrounding rock in large-span tunnel excavation becomes an important research subject.Because of the effect of complicated geological process, there are varying degrees ofjointed surfaces in the natural rock mass. A lot of research and experiments show that,the mechanical strength of the joint surfaces is much smaller than the intact rocks, andthey undermine the integrity and stability of the rock mess and get up the control actionto the jointing rock mass mechanical properties and the stability. Therefore, it isessential to analysis of the impact of the distribution and mechanical properties of jointson the large-span of the tunnel excavation in jointed rock mass. This paper, combinedwith the actual geological conditions and construction of Wulukou subway station inBeibei, Chongqing province, use the discrete element analysis software UDEC tosimulate the excavation of the large-span tunnel in the jointed rock mass. According tothe engineering geological data, this paper builds an analysis model by using UDECsoftware, and the main research contents are:(1) The deformation and failuremechanism of the surrounding rock in the excavation process of large-span tunnel in thejointed rock mass with different joint spacing, different joint angle conditions;(2) Theimpact on the displacement of the tunnel supporting and the stability of the surroundingrock due to the change of the joint cohesion, internal friction angle conditions;(3)Analysis of the stability and deformation of the surrounding rock after the stochasticanchors supporting, confirming the feasibility and benefits of stochastic anchorssupporting method on the large-span tunnel in the jointed rock mass;(4) The effect onthe tunnel excavation by the steel concrete column supporting reinforcement scheme and the suggestion to the follow-up construction process.The study shows that：The discrete element method software UDEC can effectivelysimulate analysis of the stability and failure mechanism of surrounding rock during theexcavation process of large-span tunnel in the jointed rock mass and random anchorsupporting method can effectively increase the stability of the tunnel surrounding rockin the jointed rock mass. According to the results of this paper, the analysis can promotethe discrete element method (UDEC software) in the application of geotechnicalengineering, and provide theoretical basis and scientific guidance for the improvementof the construction technology of the large-span tunnel.