Mechanical behaviour analysis and support system field experiment of confined concrete arches

Abstract

Soft rock control is a big challenge in underground engineering. As for this problem, a high-strength support technique of confined concrete (CC) arches is proposed and studied in this paper. Based on full-scale mechanical test system of arch, research is made on the failure mechanism and mechanical properties of CC arch. Then, a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity; a calculation formula is deduced for the internal force of the arch; an analysis is made on the influence of different factors on the internal force of the arch; and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing capacity. With numerical calculation and laboratory experiment, the ultimate bearing capacity and internal force distribution is analyzed for CC arches. The research results show that: 1) CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability; 2) The key damage position of the arch is the two sides; 3) Theoretical analysis, numerical calculation and laboratory experiment have good consistency in the internal force distribution, bearing capacity, and deformation and failure modes of the arch. All of that verifies the correctness of the theoretical calculation. Based on the above results, a field experiment is carried out in Liangjia Mine. Compared with the U-shaped steel arch support, CC arch support is more effective in surrounding rock deformation control. The research results can provide a basis for the design of CC arch support in underground engineering.

Keywords

confined concrete arch / full-scale laboratory experiment / theoretical analysis / numerical experiment / field application

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