为解决2条交叠隧道小角度近距离交叉穿越时，下穿隧道施工对既有隧道稳定性影响显著的问题，依托青岛地铁8号线青沧区间隧道斜下穿既有地铁3号线隧道作为典型的近距离小角度斜下穿工况，通过ABAQUS建立有限元计算模型，分析新建隧道开挖过程中既有隧道竖向位移、水平位移及应力演化规律。施工过程中对上部既有隧道结构沉降位移实时监测，并对比分析监测数据与模拟结果的差异性。研究结果表明，在以微风化和中风化花岗岩为主的地层中，当新建隧道以小角度近距离斜下穿既有隧道时： 1）以下穿隧道与既有隧道线路交点处在既有隧道中对应的断面为最危险断面，下穿隧道对既有隧道最危险断面变形影响显著的开挖范围为，以既有隧道最危险断面在下穿隧道中的垂直投影为中心，沿开挖轴线前后20 m范围内； 2）同一隧道断面中，下穿隧道开挖导致既有隧道断面内拱顶和左腰、拱底和右腰向相反方向位移，既有隧道结构断面有扭转变形的趋势； 3）新建隧道开挖对既有隧道最大主拉应力和主压应力影响很小，应力值较大区域位于隧道底板处。

 When two overlapped tunnels crossing with small distance and angle, the underpassing tunnel construction has a significant impact on the stability of the existing operating tunnel. In this paper, a case study is conducted on Qingdao North stationCang′an Road station of Qingdao metro line 8 obliquely crossing underneath adjacent existing tunnel of Qingdao metro line 3, and the ABAQUS is used to establish a finite element calculation model to analyze the vertical and horizontal displacement and stress evolution laws of the existing tunnel in the process of new tunnel excavation. The settlement displacement of the existing upper tunnel structure is monitored in real time during construction, and the difference between monitoring data and simulation results is compared and analyzed. The results show the following: (1) The most dangerous crosssection of the existing tunnel is located at the intersection of the upper and lower tunnels, and the excavation range of the crosssection of the existing tunnel with most adverse condition is 20 m ahead of and behind the crosssection of the new tunnel at intersection. (2) In a same tunnel crosssection, the underpass tunnel construction will cause displacement of the arch and the left waist and the arch bottom and the right waist in the existing tunnel in an opposite direction, and the existing tunnel structure crosssection has a tendency of torsional deformation. (3) The excavation of new tunnel has little influence on the maximum principal tensile stress and compressive stress of existing tunnel, and the tunnel bottom plate has a larger stress.