Modeling and Experimental Study of Mechanical Properties of Confined Concrete Arch in Complicated Deep Underground Engineering

Abstract

Control of surrounding rocks is one of the major problems in deep underground engineering under complicated conditions, such as high stress and tectonic fracture zones. This study proposed a three-dimensional confined concrete support system (CCSS) and investigated its main component: the confined concrete (CC) arch. The authors derived an internal force calculation formula for a circular arch with any number of sections and studied the effects of load, lateral pressure coefficient, node rigidity ratio, and other factors on the internal force distribution. In the analysis of CC part strength, damage first occurred to the CC159 × 10-C40 arch on both sides of the right and the left casings at an ultimate bearing capacity of 2,210 kN. To verify the correctness of the theoretical calculation and investigate the mechanical properties and damage mechanism of the arch, a full-scale indoor test on the CC159 × 10-C40 arch was conducted, and a 1:1 large-scale test system was developed. The authors found that the arch ultimate bearing capacity under the same load was 2,003.2 kN, a difference of only 9.36% compared with the theoretical calculation. The arch damage mechanism and key damaged parts were found to be consistent with the predictions of the theoretical calculations. The results of this research provide evidence for the design and analysis of CC arches.