Application of concrete-filled steel tubular support in unified strength-bearing ring theory

Abstract

This paper takes the deep high-stress fractured soft-rock roadway of Jinfeng Gold Deposit as the research object, analyzes the stress state and deformation failure reasons of the roadway via on-site surveys and physical and mechanical test of the surrounding rock, and reveals the main control difficulties of roadway. The axial compression performance tests of circular and square concrete-filled steel tubular (CFST) columns were carried out. A unified strength-bearing ring mechanical model was established, and the bearing ring strengthening composite support mechanism was clarified. The results show that the bearing capacity of circular CFST column is 1.20 to 1.43 times that of square CFST column when the steel content, concrete strength, and wall thickness of the steel tube were identical. When the intermediate principal stress influence coefficient b = 0, the roadway stability criterion of the unified strength-bearing ring and the bearing ring was consistent, indicating the correctness of the unified strength-bearing ring theory. Engineering practice has shown that, based on the support scheme of circular CFST support, the deformation of the two sides and roof decreased by 82.35 % and 73.12 % respectively, effectively controlling the deformation of the roadway surrounding rock, which is an important guiding significance for the roadway support under similar conditions.