盾构隧道斜螺栓接头受力性能与火灾下温度分布规律

Mechanical properties of shield tunnel with inclined bolt joint and temperature distribution law under fire

利用有限元计算软件ABAQUS建立了环向复合管片与环向斜螺栓接头的三维实体模型;考虑复合管片材料的非线性,采用弹塑性本构模型,分析了环向斜螺栓接头在常温下的力学特性;根据HC升温曲线,分析了接头模型的传热特性,研究了复合管片衬砌和环向斜螺栓接头在火灾下的温度分布规律。分析结果表明:采用高强螺栓能够有效减小接头张开量,增大接头刚度;在采用高强螺栓的情况下,斜螺栓最大轴应力易在初始阶段达到屈服,屈服后接头弯矩和轴力的增大对斜螺栓的应力影响并不大,但对斜螺栓变形影响较大,当接头负弯矩从7kN·m增加到122kN·m,接头轴力从368kN增加到734kN时,斜螺栓最大应变增加1.6倍,当接头正弯矩从53kN·m增加到182kN·m,接头轴力从903kN增加到1 056kN时,斜螺栓最大应变增加5.9倍;常温下接缝附近斜螺栓的轴应力呈现反对称分布,除接缝外其他部位斜螺栓的轴应力基本相等,约为400MPa,接缝处轴应力绝对值最大值可达700MPa;火灾情况下手孔处温度上升最快且达到的温度最高,80min时即可达到1 000℃,接缝处混凝土在100min后达到稳定温度,螺母处混凝土在150min后达到稳定温度,稳定温度均为1 000℃左右。

A three-dimensional solid model of circumferential composite segments and the circumferential inclined bolted joint was established using the finite element calculation software ABAQUS.The nonlinearity of the composite segment material was considered,and the elastoplastic constitutive model was adopted.The mechanical properties of the circumferential inclined bolted joint under normal temperature were analyzed.According to the heating up curve of HC,the heat transfer characteristics of the joint model were analyzed,and the temperature distribution laws of the composite segment lining and the circumferential inclined bolted joint under fire were studied.Analysis result shows that the use of a high-strength bolt can effectively reduce the opening of the joint and increase the joint stiffness.For high-strength bolts,the maximum axial stress of the inclined bolt is easy to yield at the initial stage,and the increase inbending moment and axial force of the joint has little influence on the stress of the bolt,but has more influence on deformation of the bolt.When the negative bending moment of the joint increases from 7kN·m to 122kN·m,the axial force of the joint increases from 368 kN to734kN,and the maximum strain of the inclined bolt increases by 1.6times.When the positive bending moment of the joint increases from 53kN·m to 182kN·m,and the axial force of the joint increases from 903 kN to 1 056 kN,the maximum strain of the inclined bolt increases by5.9times.Under the normal temperature,a special antisymmetric distribution of the axial stress of the inclined bolt is shown near the seam.The axial stresses of the inclined bolt,except the joints are equal,is about 400 MPa,and the maximum absolute value of the axial stress at the joint can reach 700 MPa.In a fire,the fastest temperature rise is at the hand hole,and if the temperature reaches its highest,it can reach 1 000℃in 80 min.The temperature of concrete at the seam reaches a stable temperature after 100 min,and at the nut after 150 min.This stable temperature is about 1 000℃.