节段预制拼装综合管廊承插式接头抗弯性能研究

Bending Behavior of Bell and Spigot Joints of Segmental Precast Utility Tunnel

抗弯刚度是表征接头抗弯性能的重要力学参数,为给预制拼装综合管廊承插式接头抗弯设计提供理论依据,开展了等尺寸承插式接头抗弯力学性能试验,研究了弯矩作用下接头应变、挠度、张开高度、底部张开量、转角等参数变化规律及破坏特征,并计算接头抗弯刚度。建立了预制拼装综合管廊承插式接头抗弯力学模型,推导了接头抗弯刚度计算解析表达式,并采用有限元软件ABAQUS建立了接头抗弯数值模型,对比分析了3种方法计算得到的接头张开距离、张开高度和转角随弯矩的变化规律,以验证接头力学模型与数值模型的正确性。结果表明:接头抗弯刚度计算解析公式及有限元数值模型计算得到的接头张开高度、接头转角和底部张开距离随弯矩变化规律均与试验结果基本相同,三者结果吻合良好,验证了接头力学模型与数值模型的正确性;预制拼装综合管廊承插式接头受弯变形可分为3个阶段(全截面受压阶段、弹性阶段及极限承载阶段);接头屈服弯矩约为极限弯矩的83%,接头屈服张开距离与转角约为极限状态的1/3;弹性阶段抗弯刚度为40000 kN·m·rad^(-1),极限承载阶段抗弯刚度为5461 kN·m·rad^(-1);弯矩作用下承插式接头顶部外侧和承口端底部受压开裂破坏,插口端顶角出现混凝土剥落导致接头破坏。研究结果可为预制拼装综合管廊承插式接头抗弯性能安全评价与设计提供科学依据。

Bending stiffness is a critical mechanical parameter for characterizing the bending performance of joints.Mechanical bending performance tests of equal-sized bell and spigot joints were conducted to investigate the variation trends of joint strain,deflection,opening height,bottom opening,and rotation angle under bending moments and the failure characteristics of joints,and to calculate the bending stiffness of the joints,to provide a theoretical reference for the bending design of bell and spigot joints in precast utility tunnels.A mechanical analytical model for the bell and spigot joints of a precast utility tunnel was established,and analytical formulas for the bending stiffness of the joint were derived for theoretical calculations.A numerical model of the bending stiffness of the bell and spigot joints was established using the finite-element software,ABAQUS.The variations in the joint opening distance,opening height,and rotation angle with the bending moment were compared and analyzed to verify the accuracy of the mechanical analytical model of the joint.The results show that the variations in the joint opening height,joint rotation angle,and bottom opening distance with the bending moment calculated using the analytical formula for bending stiffness and the finite-element numerical model are similar to those of laboratory tests.Moreover,the results of the three methods are in good agreement,verifying the accuracy of the joint mechanical analytical model.The bending deformation of the bell and spigot joint of the precast utility tunnel can be divided into three stages:full-section compression,elastic,and ultimate bearing.The yield bending moment of the joint is approximately 83%of the ultimate bending moment,and the joint yield opening distance and rotation angle are approximately 1/3 of that of the ultimate state.The bending stiffness values in the elastic and ultimate bearing stages are 40000 and 5461 kN·m·rad^(-1),respectively.When subjected to bending moments,the top outer side of the bell and spigot joint and the bottom of the bell end are cracked and damaged under compression,whereas the top corner of the spigot end undergoes concrete spalling,resulting in joint failure.The results provide a scientific basis for the safety evaluation and design of the bending performance of bells and spigot joints in precast utility tunnels.