Study of phyllite tunnel face stability based on discrete element method
During the construction of phyllite tunnel,due to the weak and broken surrounding rock,instability and collapse often occur near the tunnel face.In this paper the discrete element software PFC is used to simulate the triaxial test of carbonaceous phyllite,and the mesoscopic parameters of surrounding rock materials are figured out,so as to establish a three-dimensional discrete element numerical calculation model of tunnel site area,and to simulate the whole process of excavation and support under different excavation footage and excavation methods.The development principles of tunnel face displacement and the distribution range of excavation disturbance area after tunnel excavation are analyzed,and the instability mechanism of tunnel face in phyllite tunnel is revealed.The numerical calculation results show that:with the increase of excavation footage,the range of tunnel excavation disturbance area increases;among the different excavation methods,the excavation disturbance area of the step method is the smallest.The relevant research could provide reference for the design and construction of similar tunnels with weak and fragmented surrounding rocks.
phyllite tunneltunnel face stabilitydiscrete element methodPFCscale model
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