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Study on the Influence of Stirrups Confinement Range on Axial Compressive
Behavior of Tunnel Steel-reinforced Concrete Structures
(1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology,Chengdu 610059; 2. China Railway Eryuan Engineering Group Co., Ltd., Chengdu 610031;
3. China Railway Engineering Service Co., Ltd., Chengdu 610083)
Abstract To improve the collaborative load-bearing capacity and deformation ductility of profile steel and shot?
crete support, a new tunnel initial support structure was proposed, where stirrups are arranged circumferentially along the steel flange surface. Axial compression tests and numerical simulations were conducted on steel-reinforced concrete columns with and without stirrups, as well as those with different stirrup confinement ranges, to study the failure characteristics of steel-reinforced concrete columns with or without stirrups and the impact of stirrup confinement range on their load-bearing capacity. The results show that under axial compression, when there are no stirrups, the interface between the steel and shotcrete is prone to separation, preventing them from working together in bearing load. However, circumferential stirrups placed along the steel flange can effectively constrain the deformation of the concrete in the core zone, increasing the bond-slip strength between the steel and the concrete,thereby enhancing the ultimate load-bearing capacity and ductility. Compared with specimens without stirrups of the same section type, the ultimate load-bearing capacity increased by 28.29%, 30.87%, and 35.57% for specimens with circumferential stirrup extension lengths of 0 mm, 30 mm, and 60 mm, respectively. The ultimate load-bearing capacity of the stirrup-confined steel-reinforced concrete columns increased as the circumferential stirrup extension length increased. Considering all factors, the optimal stirrup extension length is 45 mm.
Abstract：
To improve the collaborative load-bearing capacity and deformation ductility of profile steel and shot?
crete support, a new tunnel initial support structure was proposed, where stirrups are arranged circumferentially along the steel flange surface. Axial compression tests and numerical simulations were conducted on steel-reinforced concrete columns with and without stirrups, as well as those with different stirrup confinement ranges, to study the failure characteristics of steel-reinforced concrete columns with or without stirrups and the impact of stirrup confinement range on their load-bearing capacity. The results show that under axial compression, when there are no stirrups, the interface between the steel and shotcrete is prone to separation, preventing them from working together in bearing load. However, circumferential stirrups placed along the steel flange can effectively constrain the deformation of the concrete in the core zone, increasing the bond-slip strength between the steel and the concrete,thereby enhancing the ultimate load-bearing capacity and ductility. Compared with specimens without stirrups of the same section type, the ultimate load-bearing capacity increased by 28.29%, 30.87%, and 35.57% for specimens with circumferential stirrup extension lengths of 0 mm, 30 mm, and 60 mm, respectively. The ultimate load-bearing capacity of the stirrup-confined steel-reinforced concrete columns increased as the circumferential stirrup extension length increased. Considering all factors, the optimal stirrup extension length is 45 mm.
LU Junfu1 LI Ming1 ZHAO Wanqiang2 CHEN Long3
.Study on the Influence of Stirrups Confinement Range on Axial Compressive
Behavior of Tunnel Steel-reinforced Concrete Structures[J] MODERN TUNNELLING TECHNOLOGY, 2025,V62(1): 250-258
2025, Vol. 62 