Abstract
In the construction of the Loess Plateau in China, high‐filled cut‐and‐cover tunnels (HFCCTs) had solved the problem of the shortage of land resources. However, this type of structure has a large amount of backfill soil, which leads to the problems of ultrahigh earth pressure and safety of the cut‐and‐cover tunnels (CCTs) lining structure. Previous studies have focused on the load reduction of various flexible materials, ignoring the influence produced by the shape of the CCT structure on the load reduction. Therefore, via a discrete element software, we investigated the changes of vertical earth pressure (VEP), vertical displacement, lateral earth pressure (LEP), and load transfer mechanisms around a HFCCT with consideration to two cases: (1) different shape of CCT structure; (2) the coupling of load reduction using expanded polystyrene (EPS) and the modified shape of the CCT lining structure. The results obtained by the discrete element method (DEM) revealed that an appropriate structural shape influenced the reduction of the VEP above the CCT and that the coupled effects of the load reduction using the EPS and shape modifications of the CCT lining structure could significantly reduce the VEP above the CCT, which enhanced the safety of the CCT. Meanwhile, the optimal values for the shapes of CCTs are derived.
Highlights
In the Loess Plateau of Northwest China, deep valleys pose challenges in the construction of high-speed railways and highways, and a certain amount of backfill soil is required.us, high-filled cut-and-cover tunnels (HFCCTs) are employed
The contact force chains on both sides of the cutand-cover tunnel (CCT) area gradually became sparse. is change is consistent with the results presented in Figure 6 for which the change of the H/S ratio had a greater effect on the earth earth pressure above the CCT without the expanded polystyrene (EPS) load reduction
Seen, the load reduction results that are oval zones with sparse contact force chains were essentially the same, and the contact force chains were sparse on both sides of the CCT with the increase of the H/S ratio. is change is consistent with the results shown in Figure 6(b), for which the change of the H/S ratio had a greater effect on the earth earth pressure outside of the CCT with the EPS load reduction
Summary
Us, high-filled cut-and-cover tunnels (HFCCTs) are employed. Such high fill causes an overload of earth pressure above the tunnel, which can adversely affect the safety of the tunnel and cause longitudinal cracking. Erefore, to ensure the safety of the tunnel’s lining structure, reasonable measures are required. By laying a flexible material above the structure and investigating the structure-soil interaction effect, it was concluded that a good load reduction effect can be achieved by laying a flexible material plate above the structure [2,3,4,5,6,7]. The effects of different load reduction measures have been analyzed through laboratory tests [8] and finite element simulations [9]. A large number of compressible materials, such as leaves [10], baled straw [11], sawdust or Advances in Civil Engineering woodchips [12], expanded polystyrene (EPS) [13,14,15], and geogrid [16,17,18] have been investigated
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
