Calculation method of calculating rock pressure of deeply buried double-arch tunnel without middle drift

The multi arch tunnel without a central guide tunnel avoids the drawbacks of traditional multi arch tunnel construction processes such as complexity and frequent stress conversion. In recent years, it has been widely used in China, but there is no unified standard for calculating the surrounding rock pressure of this new structure. Based on the Prussian theory and process design method, considering the inhibitory effect of the support structure of the advance tunnel on the collapse arch height of the subsequent tunnel and the intensifying effect of the excavation of the subsequent tunnel on the surrounding rock pressure of the advance tunnel, a process load calculation method for deep buried multi arch tunnels without a central guide tunnel was established. Finally, the rationality of the process load calculation method was verified by comparing and analyzing with the monitoring and measurement results of typical engineering sites and reference calculation methods. The research results indicate that determining the support capacity of the advance tunnel support structure through the combination of stress distribution can quantify the inhibitory effect on the surrounding rock pressure of the subsequent tunnel; Quantitative analysis of the four main factors that affect the degree of influence on surrounding rock pressure (rock level S (32.66%), excavation width W1 (28.02%) of the front tunnel ,excavation width W2 (22.34%) of the rear tunnel, and support strength G (16.99%) of the front tunnel) makes the value of the coefficient of influence of rear tunnel excavation on the surrounding rock pressure of the front tunnel more reasonable. By solving the process load calculation method for deep buried multi arch tunnels without central guide tunnels, a more scientific and reasonable design basis can be provided for the support structure of multi arch tunnels without central guide tunnels.