Open AccessAnalysis of mechanical behavior of a pipe-roof based on model of anisotropic plate on elastic foundation
Author(s) -
Song Wu,
Zhi Cheng-jie,
Hua Tang,
Dai Yonghao
Publication year - 2020
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.179
H-Index - 26
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/570/5/052070
Subject(s) - foundation (evidence) , roof , isotropy , stiffness , structural engineering , arch , geotechnical engineering , stress (linguistics) , finite element method , deformation (meteorology) , beam (structure) , geology , engineering , law , physics , linguistics , philosophy , oceanography , quantum mechanics , political science
According to the equivalent stiffness method of elastic theory, pipe roofs can be regarded as stiffening ribs and reinforced rock and soil can be regarded as an isotropic plate. Hence, pipe roofs and reinforced rock and soil in the local area of tunnel’s arch crown can be considered as an anisotropic plate on an elastic foundation with specific constraints on the four edges. To improve the traditional elastic foundation beam model for pipe roofs, an anisotropic plate model of a pipe roof on an elastic foundation is established. The hyperbolic model is adopted for the foundation reaction. The mechanical model of a pipe roof is extended from one to two dimensions and solved by finite element method via the COMSOL partial differential equation (PDE) module. The model is used to analyze the mechanical behavior of a pipe-roof for a shallow-buried and soft rock highway tunnel. Meanwhile, the calculated results of the hyperbolic and traditional models (Pasternak model and Winkler model) are compared and analyzed. The results show that the following: (1) The stress and deformation of pipe roofs mainly appear in the section no more than 6 m ahead of the working face. The pipe roof plays a role of a supporting beam to improve the stabilization of the working face. It can effectively transfer the upper load to the un-excavated section and better distribute the stress of surrounding rock. (2) The 2D pipe-roof model overcomes defects of traditional models that cannot simulate the plane stress of the reinforced area and provides a reference for the design and construction of pipe-roofs. The longitudinal bending moment ( M y ) is about 14 times the size of the lateral bending moment ( M x ), which indicates that the pipe-roof has an obvious effect on M y along the tunnel. M x however cannot be neglected. (3) The maximum deflection difference between the hyperbolic model and Pasternak model is about 5%, and the calculated results are in good agreement with each other. The hyperbolic model considers the monotonous and bounded characteristics of sub-grade reaction varying with the displacement. The basis of the model is verified and extent of its accuracy is demonstrated.