中文摘要：

基于多尺度混合建模技术和非线性接触理论，建立考虑管片接头细部构造和静动应力累积的盾构隧道精细化数值计算模型，研究盾构正交下穿施工扰动下，既有隧道管片结构(含接头)的静动力力学特性。研究结果表明：新建盾构隧道的下穿施工将引起既有隧道管片结构纵向不均匀下沉，并伴有一定的扭转；管片接头变形、螺栓内力和接头混凝土应力均表现出波动性增长，其峰值出现在既有隧道中部及其前后约6m处；下穿施工扰动下，既有隧道管片拱腰处纵缝接头张开量的增加与拱底环缝接头错台量的增长分别对隧道的防水及螺栓受力不利；螺栓所在位置拉应力集中明显且显著增长，接近管片混凝土极限抗拉强度。在列车荷载作用下，管片接头变形，螺栓内力和管片应力3项指标表现出相似的变化规律，在轮轨经过时，量值迅速增大并产生剧烈波动，其中螺栓剪力和动拉应力在轮轨荷载交替时存在一定叠加效应。

英文摘要：

In this paper,a numerical model of local refined shield tunnel was established,which took detailstructure of section joint and static-dynamic stress accumulation into account.The model used multi-scale methodand was based on the theory of non-linear contact.The paper analyzed the mechanical properties and deformationbehavior of the segment structure including its joints under the static and dynamic loads,when a new tunnel wasexcavated underneath.The result shows:The undercrossing construction of shield tunneling could causelongitudinal uneven subsidence of tunnel segments,along with some degree of torsion and a fluctuating growth ofsegment joint deformation,bolt stress,and segment stress,all three of which reach their peak values at typicalsections including middle section of existing tunnel and six meters in front of and behind it.Due to theorthometric undercrossing disturbance,the opening amount of longitudinal joint at arch-haunch and dislocationamount of circular joint at arch-bottom would increase,putting the water proofness of tunnel lining and mechanical property of bolt in an unfavorable position;tensile stress concentrates and increases in concrete at the position ofbolt,approaching to the ultimate tensile strength of concrete segment.Segment joint deformation,bolt stress,andsegment stress respond similarly to train load:when the wheel passes,their values increase rapidly and fluctuatesharply,among which the bolt shear and dynamic tensile stress would superimpose when wheel load alternates.