Subsidence induced by human activity and urbanization isdistributed in an area or along a line. In Shanghai, China, land subsidenceis distributed along the belt near a subway line. The subsidenceis caused by train vibration as well as regional land subsidence and otherengineering activity. In order to figure out the mechanical response of thetunnel surroundings, the PFC2D software based on a discrete element methodis introduced to simulate a section of the metro tunnel. The linear contactbond model was employed to reflect the characteristics of clay. Based on theanalysis of stress and settlement caused by dynamic cyclic loading, themechanical response law and subsidence mechanism were investigated. Inaddition, the influence of frequency on settlement was also analyzed: thegreater the frequency, the more particles were rearranged and the largerthe settlement. The fraction of sliding contacts was introduced toexplain this phenomenon. The results can be used to understand, predictand control land subsidence to protect the geological environment.
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