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A Study on the Bearing Characteristics of Composite Concrete-filled Steel Tube Support Structure in Tunnels
(1. School of Transportation Engineering, Shandong Jianzhu University, Jinan 250101; 2. China Construction Civil Engineering Co.,Ltd., Jinan 250101; 3. School of Civil Engineering, Ludong University, Yantai 264025; 4. The First Company of China Eighth Engineering Bureau Ltd., Jinan 250000)
Abstract To investigate the deformation and failure characteristics and bearing mechanism of composite concretefilled steel tube support structure, pure bending indoor tests and refined numerical simulation are carried out for support structures, taking into account the arch frame-concrete bond-slip characteristics on the basis of typical failure mode of support structures. An in-depth analysis is conducted on the mechanical response of the specimens under the action of bending moment, so as to clarify the impact pattern of different parameters, such as arch frame installation position, shotcrete strength, steel mesh diameter and protective layer thickness, on the structural bearing capacity. The results show that the concrete-filled steel tube specimens without steel mesh (SRCS-FW) are weaker in strength, the concrete cracks rapidly and then slips with the arch frame, while the concrete-filled steel tube specimens with double-layer steel mesh (SRCS-FS) are better in terms of deformation effect and display better bearing characteristics later. Besides, the SRCS-FS specimen has a higher strength of critical slip failure and its ultimate bending moment is 40.9% higher than that of the SRCS-FW specimen. Furthermore, the synergistic effect of the arch frame, the steel mesh and the concrete is significant in the elastic deformation phase of the component. The tensile force of the specimen in the cracking phase is mainly shared by the tensile-side steel mesh and the arch frame, while the pressure is shared by the arch frame and the concrete under compression. It is suggested that the parameter design for the support structure should take into account its load-bearing performance, economy and engineering experience, and construction convenience.
Abstract：
To investigate the deformation and failure characteristics and bearing mechanism of composite concretefilled steel tube support structure, pure bending indoor tests and refined numerical simulation are carried out for support structures, taking into account the arch frame-concrete bond-slip characteristics on the basis of typical failure mode of support structures. An in-depth analysis is conducted on the mechanical response of the specimens under the action of bending moment, so as to clarify the impact pattern of different parameters, such as arch frame installation position, shotcrete strength, steel mesh diameter and protective layer thickness, on the structural bearing capacity. The results show that the concrete-filled steel tube specimens without steel mesh (SRCS-FW) are weaker in strength, the concrete cracks rapidly and then slips with the arch frame, while the concrete-filled steel tube specimens with double-layer steel mesh (SRCS-FS) are better in terms of deformation effect and display better bearing characteristics later. Besides, the SRCS-FS specimen has a higher strength of critical slip failure and its ultimate bending moment is 40.9% higher than that of the SRCS-FW specimen. Furthermore, the synergistic effect of the arch frame, the steel mesh and the concrete is significant in the elastic deformation phase of the component. The tensile force of the specimen in the cracking phase is mainly shared by the tensile-side steel mesh and the arch frame, while the pressure is shared by the arch frame and the concrete under compression. It is suggested that the parameter design for the support structure should take into account its load-bearing performance, economy and engineering experience, and construction convenience.
SUN Huibin1 ZHANG Jianli2 YANG Huixiang1 YANG Hui2 WANG Lei3 WEI Jun2 LIN Weinan3
.A Study on the Bearing Characteristics of Composite Concrete-filled Steel Tube Support Structure in Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(2): 103-114
2023, Vol. 60 