剪切荷载作用下盾构隧道带新型定位榫管片的力学特性

Mechanical Characteristics of New Type Positioning TenonSegment of Shield Tunnel under the Action of Shear Load

基于成都某地铁工程应用的一种带新型定位榫的盾构隧道管片结构,运用ABAQUS软件分别建立有无定位榫的管片接头三维精细化模型,研究该定位榫对连接螺栓受力、管片塑性区分布以及管片错台量的影响,探究其在管片结构抗剪中的作用机理。结果表明:定位榫在管片受剪时承担总剪力的52%;定位榫能显著降低螺栓的受力,有定位榫后螺栓的轴力峰值至少下降75.1%、剪力峰值下降76.4%;有定位榫后螺栓塑性应变范围有所增大,但螺栓上下两侧的塑性应变峰值分别减小80.5%和90.6%;固定定位榫的凹槽对管片接缝面有削弱作用,导致管片环向和纵向的相对塑性区宽度分别增加93.7%和44.2%,但管片的最大塑性应变峰值减小7.2%,同时螺栓对管片径向的挤压也有所减小;剪切荷载小于460 kN时,带定位榫的管片错台量略大,剪切荷载超过460 kN后,带定位榫管片的错台量更小且增长速率更低。带新型定位榫的盾构隧道管片能够有效保护连接螺栓,改善接头力学性能。

Based on a shield tunnel segment structure with a new type positioning tenon used in a metro project in Chengdu,the three-dimensional refined models of segment joints with and without positioning tenon were established through ABAQUS software.The effects of the positioning tenon on the connecting bolt force,the distribution of segment plastic zone and the segment misalignment were studied,and the mechanism of the tenon in shear resistance of segment structure was explored.The results show that the positioning tenon can bear 52%of the total shear force when the segment is sheared.It can also significantly reduce the force of the bolt.After adding the positioning tenon,the peak axial force of the bolt is reduced by 75.1%at least,and the peak shear force is reduced by 76.4%.The plastic strain range of the bolt with positioning tenon increases,but the peak plastic strain of the upper and lower sides of the bolt decreases by 80.5%and 90.6%respectively.The grooves of the fixed positioning tenon weaken the joint surface of the segments,resulting in an increase of 93.7%and 44.2%in the circumferential and longitudinal relative plastic zone width of segments.However,the peak value of the maximum plastic strain of segment decreases by 7.2%,and the radial compression of the bolt on the segment is also reduced.When the shear load is less than 460 kN,the segment misalignment with positioning tenon is slightly larger,but when the shear load exceeds 460 kN,the segment misalignment with positioning tenon is smaller with lower growth rate.In conclusion,the shield tunnel segment with the new positioning tenon can effectively protect the connecting bolts and improve the mechanical performance of joints.