Deep underground projects (e.g., coal mines), are often faced with complex conditions such as high stress and extremely soft rock. The strength and rigidity of the traditional support system are often insufficient, which makes it difficult to meet the requirements of ground control under complex conditions. As a new support form with high strength and rigidity, the confined concrete arch plays an important role in controlling the rock deformation under complex conditions. The section shape of the tunnel has an important impact on the mechanical properties and design of the support system. However, studies on the mechanical properties and influence mechanism of the new confined concrete arch are rarely reported. To this end, the mechanical properties of traditional U-shaped steel and new confined concrete arches are compared and comparative tests on arches of circular and straight-leg semicircular shapes in deep tunnels are conducted. A large mechanical testing system for underground engineering support structure is developed. The mechanical properties and influence mechanism of confined concrete arches with different section shapes under different loading modes and cross-section parameters are systematically studied. Test results show that the bearing capacity of the confined concrete arch is 2.10 times that of the U-shaped steel arch, and the bearing capacity of the circular confined concrete arch is 2.27 times that of the straight-leg semicircular arch. Among the various influencing factors and their engineering parameters, the lateral stress coefficient has the greatest impact on the bearing capacity of the confined concrete arch, followed by the steel pipe wall thickness, steel strength, and core concrete strength. Subsequently, the economic index of bearing capacity and cost is established, and the optimization design method for the confined concrete arch is proposed. Finally, this design method is applied to a high-stress tunnel under complex conditions, and the deformation of the surrounding rock is effectively controlled.

深部地下项目（例如煤矿）经常面临复杂的条件，例如高应力和极软的岩石。传统支撑系统的强度和刚度往往不足，难以满足复杂工况下的地面控制要求。约束混凝土拱作为一种高强度、高刚度的新型支护形式，在复杂条件下控制岩石变形发挥着重要作用。隧道断面形状对支护系统的力学性能和设计有重要影响。然而，关于新型约束混凝土拱的力学性能及其影响机制的研究却鲜有报道。为此，对传统U型钢拱与新型约束混凝土拱的力学性能进行了对比，并进行了深埋隧道圆形与直腿半圆形拱的对比试验。开发了地下工程支护结构大型力学测试系统。系统研究了不同截面形状的约束混凝土拱在不同加载方式和截面参数下的力学性能及其影响机制。试验结果表明，约束混凝土拱的承载力是U型钢拱的2.10倍，圆形约束混凝土拱的承载力是直腿半圆形拱的2.27倍。在各种影响因素及其工程参数中，侧向应力系数对约束混凝土拱的承载力影响最大，其次是钢管壁厚、钢材强度、核心混凝土强度。随后建立了承载力和造价的经济指标，提出了约束混凝土拱的优化设计方法。最后将该设计方法应用于复杂条件下的高应力隧道，围岩变形得到有效控制。