装配式隧道圆形和方形钢榫接头抗弯性能大尺寸试验

接头是装配式隧道建设和运营阶段最为薄弱和关键的部位,其设计及力学性能评估是一项必要的研究工作。为评估圆形和方形钢榫接头的抗弯性能,开展了大尺寸接头抗弯试验,研究了接头在荷载作用下的竖向挠度、接缝张开量及应变变化规律,探讨了其接头旋转角、延性、断裂韧性及破坏模式。研究结果表明:圆形钢榫接头的承载能力弱于方形钢榫接头,极限荷载及其对应的挠度分别比方形钢榫接头小77.71 kN和6.797 mm;同一荷载水平下,方形钢榫接头的张开量和旋转角更小,其抗变形能力强于圆形钢榫接头;2种钢榫接头的混凝土和钢筋应变响应规律在整体上相似,但方形钢榫接头的最大压应变仅为圆形钢榫接头的15%;圆形钢榫接头表现出渐进失效行为,其挠度延性指数和旋转延性指数分别是方形钢榫接头的2.28倍和1.98倍,且最终旋转角和单位荷载下旋转角增量均小于方形钢榫接头;2种钢榫接头受压弯曲时,圆形钢柱将荷载传递至接头底部,使混凝土受拉区破坏过大,主要表现出拉弯破坏模式,而方形钢柱联合更多承压区混凝土受荷,使承压区混凝土破损面积为圆形钢榫接头的3倍左右,主要表现出压弯破坏模式。研究结果可为装配式矩形隧道的接头设计提供参考。

Large-scale Testing of Bending Behavior of Circular and Square Steel Tenon Joints of Fabricated Tunnel

The joint is the weakest and most important part of in the construction and operation stages of prefabricated tunnels.Therefore,it is necessary to evaluate its design and mechanical properties.A bending test of large-scale joints was performed to evaluate the bending performance of circular and square steel tenon joints.The vertical deflection,joint opening,and strain under loading were studied,and the joint's rotation angle,ductility,fracture toughness,and failure mode were discussed.The results indicate that the bearing capacity of the circular steel tenon joint is weaker than that of the square steel tenon joint,and the ultimate load and its corresponding deflection are 77.71 kN and 6.797 mm smaller than those of the square steel tenon joint,respectively.Under the same load level,the opening and rotation angles of the square steel tenon joint were smaller,and its deformation resistance was stronger than that of the circular steel tenon joint.The strain response laws of the concrete and reinforcement of the two types of steel tenon joints are similar overall,but the maximum compressive strain of square steel tenon joints is only 15% of that of circular steel tenon joints.The deflection ductility index and rotation ductility index of circular steel mortise joint are 2.28 times and 1.98 times higher than those of square steel mortise joint,respectively,and the increment of final rotation angle and rotation angle under unit load are less than those of square steel mortise joint.When the two types of steel tenon joints were pressed and bent,the circular steel column transmitted the load to the bottom of the joint so that the damage to the concrete tensile area was too large,mainly showing the tensile bending failure mode.The square steel column is combined with more concrete in the bearing area so that the damaged area of the concrete in the bearing area is approximately three times that of the circular steel tenon joint,mainly showing the compression bending failure mode.The research results provide a reference for the joint design of prefabricated rectangular tunnels.