约束混凝土箱型钢拱架是箱型钢和核心混凝土形成的组合拱架结构,也是有效控制软岩隧洞变形的一种新型支护形式,目前尚缺少关于这类拱架承载特性的研究工作。为此,推导了约束混凝土箱型截面压弯屈服判据,分析了该类型拱架的强度极限承载力和结构稳定极限承载力,同时对比了约束混凝土箱型钢拱架、H型钢拱架、箱型钢拱架3种类型拱架的承载特性。研究结果表明:约束混凝土箱型钢拱架截面屈服判据值在同型号中最高,其轴压屈服强度极限平均为箱型截面的1.4倍、H型钢截面的2.2倍,纯弯屈服强度极限平均为箱型截面的1.1倍、H型钢截面的1.5倍;约束混凝土箱型钢拱架强度和结构稳定极限承载力均高于同型号箱型和H型钢拱架,强度极限承载力是箱型钢拱架的1.3~1.4倍、H型钢拱架的2.2~2.3倍;结构稳定极限承载力是箱型钢拱架的1.03~1.04倍、H型钢拱架的1.10~1.27倍。约束混凝土箱型钢拱架承载特性优势显著,能够为软岩隧洞提供更为可靠和高效的支护。

Confined concrete box steel arch is a composite arch structure comprising box steel and core concrete. It is a novel support form designed to effectively control deformation in soft rock tunnels. Currently, there is limited research on the bearing characteristics of this arch type. In view of this, a compression-bending yield criterion for confined concrete box section is deduced, and the ultimate bearing capacities for strength and structural stability are analyzed respectively. Furthermore, the bearing characteristics of three arch types: confined concrete box steel arch, H-type steel arch, and box steel arch, are compared. Results indicate that the yield criterion value for the confined concrete box steel arch section is the highest among the types considered. Specifically, its axial compression yield limit is 1.4 times that of the box type and 2.2 times that of the H-type. Moreover, the pure bending yield limit is 1.1 times that of the box type and 1.5 times that of the H-type. The strength and ultimate bearing capacity of confined concrete box steel arch surpass those of the box type and H-type steel arches. The ultimate bearing capacity for strength is 1.3-1.4 times that of the box steel arch and 2.2-2.3 times that of the H-type steel arch. The ultimate bearing capacity for structural stability is 1.03-1.04 times that of the box steel arch and 1.10-1.27 times that of the H-type steel arch. Consequently, the confined concrete box steel arch exhibits significant advantages in load-bearing characteristics and can provide reliable and efficient support in soft rock tunnels.