Investigating Mechanical Behavior of Blocky Rock Mass with Inclined Ground Surface during Shallow Tunnel Construction by Trap-door Test and Discontinuous Deformation Analysis (DDA)

  • 杜 崇楠

Student thesis: Master's Thesis

Abstract

Until now subsidence during tunneling excavations has attracted tunneling researchers’ attention There have been many methods involving analytical methods numerical methods and physical tunneling models applied to investigate surface subsidence problems and results from those methods have been relative accuracy In this thesis the surface subsidence of shallow tunnels constructed following steeply inclined seams in case of passing through a discontinuous rock mass is formulated by two suggested methods: physical model (trap-door model) and numerical method (Discontinuous Deformation Analysis DDA) The trap-door model with aluminum blocks and aluminum rods arranged inside representing a discontinuous environment of a rocky block mass and its ability to rotate around a stationary axis showing steeply inclined strata are demonstrated to determine the surface subsidence of the ground by lowering the trap-door with assigned distances which simulates as a real shallow tunnel in construction process Meanwhile a numerical method (DDA) proposed by Shi (1989) is also applied to simulate the similar shallow tunnel with unchanged conditions and results of the surface subsidence profiles are obtained again By comparing the results of two methods discussions about advantages and disadvantages of each of methods are carried out and to conceive how accurate DDA is for this application? With the collated subsidence data from two methods it can be seen that the surface subsidence results achieving from DDA calculations agree with those measured from trap-door model DDA can not only simulate behaviors of an artificial shallow tunnel in a steeply inclined rock strata but also gain suitable results of the surface subsidence stress distribution and arching effect It will be a potential method for analyzing mechanical behaviors of steeply inclined rock masses during practical shallow tunnel excavation
Date of Award2014 Feb 6
Original languageEnglish
SupervisorJian-Hong Wu (Supervisor)

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