重叠隧道的施工力学研究

由于地下空间的不断利用，出现了重叠隧道。这种形式布局的隧道在第1孔隧道完成之后，引起了地层内初始应力的变化，而且由于地层中已有一个相邻的已衬砌隧道，地层的刚度条件不再与单孔隧道的垂直轴对称，第2孔隧道的修建又要对已建的第1孔隧道发生影响。应用ANSYS程序对深圳地铁1期工程中的3种典型的重叠断面的计算表明：重叠隧道地表和拱顶下沉及两隧道间土体的稳定难于控制，上面第1孔隧道易发生结构整体下沉。

RESEARCH ON CONSTRUCTION MECHANICS OF OVERLAPPING TUNNELS

Overlapping tunnels have emerged in facilitating the underground space utilization. The initial stresses in ground will be changed by the first excavation, and the ground stiffness is no longer symmetrical to the vertical single tunnel axis because of the adjacent lined tunnel in the ground. The construction of the second tunnel has effect on the first constructed tunnel. ANSYS program is used to analyze three typical sections of overlapping tunnels of the first-phase of the project of Shenzhen metro. Analysis results show that the settlement of surface and arch and the stability of soil between two tunnels are difficult to control, and the settlement of upper tunnel occurs easily.