Determination of the bearing capacity of a Concrete-filled Steel Tubular arch support for tunnel engineering: Experimental and theoretical studies

Abstract

Although Concrete-filled Steel Tubular (CFST) arch support technology for transportation tunnels and mining roadways is developing rapidly, research regarding the determination of the bearing capacity of the CFST arch support is still limited. Based on a literature analysis, the definition and expression form of the bearing capacity of CFST supporting arch Qu was clarified, and determination approaches via laboratory testing and theoretical calculation methods were recommended. Full-size mechanical tests of CFST arches were performed by adhering to the suggested loading pattern that uses a number of hydraulic cylinders along the arch profile to simulate the surrounding rock pressure. The failure mode of the arches was determined as elastic-plastic instability with an extreme point. The critical criterion of global instability for the tested arch was proposed as the critical CFST section reaching the compression-bending limit. Based on the above criterion, a specific process for determining the Qu by theoretical calculation was proposed. Calculation examples show that the calculation results deviations were less than 4% compared with the tests results, and the reliability and accuracy of the new theoretical approach were thus verified. Finally, the limitations of the calculation method were noted.