河床冲淤作用下公轨合建盾构隧道纵向力学性能研究

Research on the Longitudinal Mechanical Properties of Road-Rail Shield Tunnel Under the Action of Riverbed Silting and Scouring

为研究河床冲淤作用下公轨合建盾构隧道的纵向力学性能,以某公轨合建隧道为工程背景,建立三维实体地层-结构模型,对隧道和内部结构的变形、内力以及地表的沉降进行了分析,研究了河床冲淤作用下盾构隧道的纵向受力及变形规律。研究结果表明。(1)内部结构能够增大隧道的刚度,减小隧道的不均匀沉降;河床淤积高度达到13 m时,考虑内部结构时隧道的竖向位移较之无内部结构时减小了9.4%;河床冲刷深度8 m时,考虑内部结构隧道跨中位移仅回弹了30.2%。(2)内部结构能够分担河床淤积所产生的部分荷载,使得管片内力减小,提高隧道的承载能力;在河床淤积作用下,考虑内部结构隧道最大MISES应力较未考虑内部结构时减小了27.2%。(3)隧道与内部结构在受到河床冲刷作用时发生回弹,当管片在横向上恢复的变形与内部结构在横向上恢复的变形不协同时,内部结构就会在上层侧墙与管片连接处产生挤压,产生较大的应力值,因此该部位应作为关键部位进行适当加强。(4)隧道的内部结构能够减小由于河床淤积所引起的地表沉降以及河床冲刷所引起的地表回弹。(5)内部结构在变形缝位置时的MISES应力值大于其他部位,在施工时应当注意内部结构变形缝的施工质量。

To study the longitudinal mechanical properties of the segment structure of super-large diameter shield tunnel under the riverbed silting and scouring, a three-dimensional solid stratigraphic-structural model is established. The deformation and internal force of the tunnel and internal structure as well as subsidence of the ground are analyzed, and the longitudinal force and deformation of shield tunnel under the action of riverbed deposition are studied. The results show that:(1) the internal structure can increase the stiffness of the tunnel and reduce the uneven settlement of the tunnel. When the riverbed siltation height reaches 13 m, the vertical displacement of the tunnel considering the internal structure is reduced by 9.4%compared with that without the internal structure;when the riverbed scouring depth is 8m,considering the internal structure,the mid-span displacement of the tunnel rebounds only 30.2%.(2)The internal structure can share part of the load caused by riverbed sedimentation,reduce the internal force of the segment and improve the bearing capacity of the tunnel.Under the action of riverbed sedimentation,the maximum Mises stress of the tunnel with internal structure is reduced by 27.2% compared with that without internal structure.(3)The tunnel and internal structure will rebound when being scoured by the riverbed.When the deformation of the segment recovered in the transverse direction is inconsistent with the deformation of the internal structure recovered in the transverse direction,the internal structure will squeeze at the connection between the upper side wall and the segment,resulting in large stress value.Therefore,this part should be properly strengthened as a key part.(4)The internal structure of the tunnel can reduce the surface settlement caused by riverbed deposition and the surface rebound caused by riverbed scouring.(5)The Mises stress value of the internal structure at the deformation joint is greater than that of other parts.During construction,attention should be paid to the construction quality of the deformation joint of the internal structure.