## 6 Conclusions  
The TBM cutting head limits the effective application of SRBs, so carrying out advance stress release has become a key factor in the construction process of deep-buried hard rock tunnels. This paper presents a design methodology for the ASRB parameters in a potential rockburst source area of deeply buried hard rock TBM tunnels, including the test scheme establishment method, parameter selection method, parameter space relationship, and evaluation index establishment method. In addition, the stress release and energy dissipation effects of ASRBs under different arrangement schemes are discussed in detail from the perspectives of maximum principal stress reduction and elastic strain energy release with the background of a deep-buried tunnel project in southwest China. The conclusions are as follows. 1. The design method for ASRBs for a deeply buried hard rock TBM tunnel is proposed. This method is based on previous geological data and measured data and comprehensively considers the location of the stress release area and the degree of stress concentration. It can be effectively applied in the design of the layout plan for advance stress release boreholes in the early stage of tunnel construction. 2. By comparing the range of each factor in each stress release area fore and aft of the current tunneling head, the sensitivity of the five important design parameters of ASRBs to the stress release effect is, in descending order, \"aperture\", \"inclination\", \"included angle\", \"spacing\", and \"length\". From the perspective of engineering construction, since the \"aperture\" parameter is closely related to the on-site drilling equipment and the workload and construction difficulty of on-site construction, it is often difficult to change this parameter. By reasonably optimizing the \"inclination\", \"included angle\", and \"spacing\" parameters, the stress release effect can be better improved without increasing the construction workload and instead only optimizing the drilling layout. 3. Along the direction of a TBM, the sensitivity of various borehole parameters to the stress release effect shows a decreasing trend. This shows that the stress release effect of the surrounding rock mass close to the TBM can be greatly affected by improving the ASRB parameters, while in the deep rock mass far away from the TBM-constructed area, although there are ASRBs, the release effect is limited by the borehole parameters. From the calculation results of each factor, whether from the perspective of the average stress release rate or the average volume release energy, the \"length\" factor has no significant impact on the pressure release and energy dissipation effect of ASRBs. The levels of the \"inclination\", \"included angle\", and \"spacing\" factors have a negative correlation with the stress release effect, while the \"aperture\" factor has a positive correlation. This shows that under the factor level and simulation conditions set in this study, the layout of \"small inclination\", \"small included angle\", \"small spacing\", and \"large aperture\" ASRBs often has a better stress release effect than other layouts. (5) Along the direction of the tunnel axis, the relationship between the average stress release rate of each monitoring point is I \(\approx\) II \(>\) III \(>\) IV \(>\) V, which shows a decreasing trend along the direction of the TBM. The relationship between the average volume release energy of each area is, in descending order, \"A\({}_{1}\)\", \"A\({}_{2}\)\", \"A\({}_{3}\)\", and \"A\({}_{4}\)\", which also gradually decreases along the direction of the TBM. This shows that under the simulation environment discussed in this study, the ASRB release area is mainly concentrated in the range of one borehole diameter behind the face. Conceptualization, S.Q. ; Data curation, Z.X., M.Z. and Z.K. ; Formal analysis, Z.X. ; Funding acquisition, S.Q. ; Methodology, S.Q. and M.Z. ; Project administration, S.L. ; Resources, S.L., Y.X. and M.Z. ; Software, S.L. and Z.K. ; Supervision, Z.X., S.L. and Y.X.