| The simulation for the excavation and support of the underground opening is an extremely complex process. Usually numerical analysis are simplified into two-dimensional, to avoid the giant work load and complex geologic structure description in three-dimensional model. However because of the influence of 3-D initial stress, the geological tectonic structures, the traditional two-dimensional model often introduces a huge error to the results. In the thesis, a model to be able to consider both the different initial stress orientation and the geological tectonic structures is proposed by turning the model into an quaci-three-dimensional finite element model. The main research content and achievement is following:(1) The quasi-three dimensional for 6 point triangle element and corresponding program is developed, and the feasibility and reliability of the quasi-three dimensional element model is confirmed by contrast examples.(2)The quasi-three-dimensional 6 point contact element and corresponding program is developed, and the feasibility and reliability of the contact quasi-three-dimensional contact model is confirmed by contrast examples.(3) The quasi-three-dimensional 6 point bend girder finite element model and corresponding program is developed, and the feasibility and reliability of the 6 point bend girder quasi-three-dimensional model is confirmed by contrast examples.(4)Influences of the angle β between the horizontal principal stress position and the rock tunnels axis direction are analyzed by two-dimensional, quasi-three-dimensional and three-dimensional model, then the results are given: a)The strain relative error from the quasi-three-dimensional model is less than 10%, but the one from the plane model is about 20%. b) The stress relative error from the quasi-three-dimensional model is less than 8%, but the one from the plane model is 20%~30%. c) when β≤15° or β≥75° , two-dimensional and quasi-three-dimensional model analysis is available. But when 15° < β<75° ,...
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