Abstract
This paper experimentally analyzes the working behavior characteristics of five concrete-filled steel tube (CFST) arch supports in deep roadway based on the numerical shape function (NSF) method and structural stressing state theory. First, the measured strain data are expanded by the NSF method and modeled as generalized strain energy density (GSED) to characterize the stressing state of the supports. Then, one of the supports is taken as an example and the Mann-Kendall (M-K) criterion is adopted to detect the mutation characteristics of the support, which derives the new definition of structural failure load. Correspondingly, the stressing state modes as well as strain and stress fields for the support are proposed to verify their mutation characteristics. Finally, the common and different characteristics of stressing state, damage development and internal forces for different supports are also summarized. The analytical results of the supports explore a new analysis method for underground structures and the unseen knowledge provides a reference to more rational future design.
Highlights
With the depletion of shallow coal resources, the mining of coal resources gradually turns to the deep, and the depth of many mines even reaches more than 1000 m, which brings about serious influence of high ground stress, nonlinear rock mechanics behavior, complex geological conditions, etc. [1,2,3]
The numerical shape function (NSF) method applies generalized numerical simulation of a specific ideal physical model to construct discrete weighting function based on the concept of shape function in the finite element method (FEM), so it could overcome the shortcoming of conventional shape functions and meet the accuracy requirements for in-depth experimental analysis [27,28]
The investigation into the working behavior of five concrete-filled steel tube (CFST) arch supports with different section parameter are carried out based on the NSF method and structural stressing state theory, revealing the changing characteristics and unseen knowledge under the six-point radical uniformly distributed loads
Summary
With the depletion of shallow coal resources, the mining of coal resources gradually turns to the deep, and the depth of many mines even reaches more than 1000 m, which brings about serious influence of high ground stress, nonlinear rock mechanics behavior, complex geological conditions, etc. [1,2,3]. As for CFST structures, the steel tube can provide the confinement of internal concrete resulting in the significant increase of compressive performance and ductility, the internal concrete can improve the local buckling of the steel tube as well [9,10,11] These advantages prompt CFST supports as a new support technology to apply in deep mine roadways. It is significant for researchers to apply an innovative and effective method to a limited experimental data, so that the hidden knowledge in working behavior of the supports could be revealed; The division of stressing state stages for CFST supports, which mainly determined by load-displacement curves in experiments or simulations, is not clear enough and has some randomness to an extent, enhancing the difficulty of further analysis and even leading to incorrect analysis results. The unseen knowledge achieved in this study could provide a new angle of view to conduct structural analysis of CFST supports and a reference to the design improvement
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