Abstract: To test the reliability of the gridsteel frame applied in primary support of loess tunnel of the heavyhaul railway, a 1∶1 model test of fullring gridsteel frameconcrete structure is conducted, the deformation convergence of primary support, surrounding rock pressure, and mechanical property test of gridsteel frame and shotcrete are analyzed, and statistical analysis of deformation convergence data of primary support based on big data is studied. The study results show the following: (1) The fullring gridsteel frameconcrete structure has a high bearing capacity and large deformation coordination capacity. The H180 gridsteel frameconcrete structure can bear the loess weight equivalent of the loess stratum with a depth of 32.56 m under the limit state. (2) The gridsteel frame can be applied to a largespan loess tunnel with Grade Ⅳ and Ⅴ surrounding rocks, which ensures the stability of the surrounding rock and the safety of the primary support structure. (3) The gridsteel frame is used in the primary support of a largespan loess tunnel, and the crown settlement and horizontal convergence are well controlled, which are generally within the control values of excavation reserved deformation.

Key words:

heavyhaul railway, loess tunnel, gridsteel frame, mechanical test, deformation convergence, primary support