Abstract Based on the large-section (excavation area of 170m2) loess tunnel on the Zhengzhou-Xi'an High Speed Railway, the action mechanisms of different steel frames were studied in order to identify the applicable conditions for the profile steel frame and the lattice girder frame. In addition, site tests were carried out in the shallow old-loess tunnel with the aim of comparing the performances of the profile steel frame and lattice girder frame. The results show that the deformations of the two types of steel frames are equivalent and both their stresses are within the allowable range. However, there is less stress in lattice girder frame. Additionally, the contact pressure distribution between the rock mass and primary support with the lattice girder frame is relative uniform. There are no obvious differences between the two compound supports when it comes to controlling crown subsidence in the large-section loess tunnel, and their horizontal convergences are almost the same. Based on a concrete early strength test, the characteristic curves of the compound support and rock mass were obtained, the interaction mechanism of the rock mass and compound support was studied, and the applicable conditions of the lattice girder frame in the large-section loess tunnel and the design parameters of the primary support under different surrounding rock conditions were determined.
Abstract：
Based on the large-section (excavation area of 170m2) loess tunnel on the Zhengzhou-Xi'an High Speed Railway, the action mechanisms of different steel frames were studied in order to identify the applicable conditions for the profile steel frame and the lattice girder frame. In addition, site tests were carried out in the shallow old-loess tunnel with the aim of comparing the performances of the profile steel frame and lattice girder frame. The results show that the deformations of the two types of steel frames are equivalent and both their stresses are within the allowable range. However, there is less stress in lattice girder frame. Additionally, the contact pressure distribution between the rock mass and primary support with the lattice girder frame is relative uniform. There are no obvious differences between the two compound supports when it comes to controlling crown subsidence in the large-section loess tunnel, and their horizontal convergences are almost the same. Based on a concrete early strength test, the characteristic curves of the compound support and rock mass were obtained, the interaction mechanism of the rock mass and compound support was studied, and the applicable conditions of the lattice girder frame in the large-section loess tunnel and the design parameters of the primary support under different surrounding rock conditions were determined.
.On the Interaction Mechanism of the Primary Support and Rock Mass
in a Loess Tunnel with a Large Section[J] MODERN TUNNELLING TECHNOLOGY, 2013,V50(3): 79-86
2013, Vol. 50 