Abstract:

In the current tunnel design, the safety evaluation of primary support is the key to realize dynamic design of the primary support in tunnel construction. The deformationstructure method, which takes the displacement of key nodes as the known quantity, is established based on the matrix displacement method, namely, the structural load and internal force are directly calculated from the displacement value of key nodes, and then the safety of primary support is quantitatively evaluated according to the specification. The corresponding calculation program is compiled and the engineering application analysis is carried out relying on the Xiangluping Tunnel on ZhengzhouWanzhou Highspeed Railway. The results show that: (1) Compared with other inverse analysis methods based on displacement, the deformationstructure method has the advantages of simple principle, easy parameters selection and fast calculation speed. (2) The spatial location of key nodes should be uniform as much as possible, and the characteristic points should be taken into account, such as the arch point, the maximum span point, the foot of the wall point, etc., and the number of key nodes should not be less than 5; considering the complexity of the construction site and in order to ensure the accuracy of the results, it is suggested that the number of key nodes should be 7. (3) During tunnel construction, the safety evaluation of primary support can be carried out by using deformationstructure method based on the displacement monitoring data of key nodes.

Key words: railway tunnel, primary support, deformationstructure method, key nodes, safety evaluation