隧道钢管钢架与传统格栅钢架受力特性对比试验研究

针对传统格栅钢架和自主设计的4肢钢管钢架支护结构，利用Abaqus通用有限元软件，综合考虑钢管厚度、构件质量、材料成本等因素，系统开展2种隧道支护结构在单独受荷和共同受荷条件下的极限承载力、抗弯刚度、弯曲挠度、破坏形态等力学特性及演化规律的对比试验研究。研究结果表明： 1)钢管钢架和格栅钢架在刚度、承载力、变形破坏形态等方面存在一定差异，在用钢量相同的情况下，钢管钢架具有更高的强度和抗弯刚度，结构变形和受力亦更加合理； 2)钢管钢架自身承载力受钢管壁厚参数影响较为显著，壁厚取值过小会明显降低其承载力，但当壁厚达到一定数值时，继续增加壁厚对提高构件整体强度和抗弯刚度有限，同时会相应增加构件质量和材料成本； 3)在单独受荷条件下，格栅钢架的承载力为445 kN·m，较钢管钢架构件PG-2低393%，此时钢管钢架质量较格栅钢架略低，但每延米单价要高； 4)格栅钢架混凝土构件的极限荷载为174.6 kN·m，较钢管钢架混凝土构件C+PG-2、C+PG-6的极限荷载分别低2.7 %、30.6 %； 5)钢管钢架对于早期变形速度较大的围岩具有较好的适用性。

Comparative Tests on Mechanical Properties of Steel Tube Frame and Traditional Lattice Girder Used in Tunnel

Comparative test is conducted on mechanical properties such as ultimate bearing capacity, flexural stiffness, bending deflection, and failure form of the traditional lattice girder and the self designed four bar steel tube frame support structures under individual load and common load conditions using Abaqus general finite element software and comprehensively considering the thickness of the steel tube, member weight, material cost and other influencing factors. The results show that: (1) The flexural stiffness, bearing capacity, deformation, and failure form of the steel tube frame are different from those of lattice girder. In the case of similar steel weight, the steel tube frame has higher strength and flexural stiffness, meanwhile, the structural deformation and stress are also rational. (2) The bearing capacity of the steel tube frame is significantly affected by the thickness of the steel tube. The bearing capacity decreases with decreasing steel tube thickness. When the thickness reaches a certain value, continuing to increase the thickness will have limited effect on improving the overall strength and bending stiffness of the component, and will increase the weight and material cost of the component accordingly. (3) Under the condition of single load, the bearing capacity of lattice girder is 44.5 kN·m, which is 39.3% lower than that of PG-2 steel tube frame. Under this condition, the weight of the steel tube frame is slightly lower than that of the lattice girder, and the unit price per linear meter is higher. (4) The ultimate load of the lattice girder concrete member is 174.6 kN·m, which is 2.7% and 30.6% lower than the steel tube frame concrete members C+PG-2 and C+PG-6, respectively. (5) The steel tube frame has good applicability to the surrounding rock with a large deformation rate at the early stage.