纵向力对带榫管片环缝剪切破坏机制影响研究

Experimental Investigation of the Shear Mechanism on Mortise and Tenon Segment Lining

为明确带榫管片环缝剪切受力机制及剪切受力过程中纵向力对管片结构环间接缝抗剪性能的影响,采用苏通GIL(Gas Isolated Line)综合管廊工程所用带有分布式凹凸榫的原型管片衬砌,通过局部原型试验,对带榫管片结构在考虑不同纵向力作用下的受荷过程中环间螺栓应力、环间分布式凹凸榫表面应力、环缝张开量进行了研究。结果表明:(1)不同纵向力作用下带榫管片结构环缝剪切受力机制不同,纵向力较小时环缝凸榫受力破坏方式为多次的凸榫混凝土冲削损伤破坏,而纵向力较大时环缝凸榫破坏方式为单次的混凝土剪切破坏,凹凸榫之间形成剪切破坏面。(2)不同纵向力作用下带榫管片结构环缝凹凸榫破坏最严重位置均靠近纵向接头处,为中间凸榫;两侧凸榫损伤程度较弱,纵向力较小时两侧凸榫损伤程度高于纵向力较高时。(3)环间纵向力的增加有助于提高带榫管片结构环缝的抗剪能力,可使凸榫均匀受力,同时降低凸榫的损伤程度,避免局部区域环缝接头与凸榫表面的应力集中;实际工程中可通过螺栓复紧等方式保持环间纵向力。(4)对于环缝张开量的控制是保持纵向力的主要目的,在实际工程中,可通过环缝张开量的状态与发展,通过分阶段分析凸榫受力模式,评估环缝凹凸榫抗剪能力的发挥程度,以达到充分利用榫槽抗剪性能的目的。

This study aimed to specify the shear mechanism and longitudinal force influence on the circumferential joint of a segment lining in the process of shear loading and enhance the corresponding shear resistance.Segments with distributed mortises and tenons from the Sutong gas isolated line(GIL)comprehensive pipe gallery project were investigated using a local prototype test,and the bolt strain,surface concrete strain of mortises and tenons,and circumferential joint opening were analyzed under different longitudinal forces.The results indicate the following:(1)The shear failure mechanism for cases with different longitudinal force is not identical;several concrete damage events occur during the failure process of cases with low longitudinal force,while sudden shear failure occurs once for the failure of cases with high longitudinal force,shear surface is formed between mortises and tenons.(2)For cases with different longitudinal force,the degree of tenon damage on the vault is the most severe,which is the middle tenon,and the degree of tenon damage at the sides was relatively lower,in the real project,the tenon concrete strength on the vault can be improved to enhance the structural shear resistance;(3)The circumferential joint shear resistance increases with increased longitudinal force.Furthermore,the increased longitudinal force can help prevent contact surface stress concentration for the mortise and tenon and circumferential joint,and it can also decrease the degree of tenon damage.In the actual project,the bolt strength on the vault can be increased,and pretension bolt force can be provided to increase the longitudinal force.(4)Maintaining the circumferential joint opening is the purpose of longitudinal force application;in the actual project,through phased analysis on the mechanical tenon behavior,the time and stage of joint opening can be used to evaluate the degree of shear resistance application,and consequently the shear resistance for tenons can be fully utilized.