Quantitive Analysis Research On Bearing Capacity Of Deep Rock Tunnel

After the land is digged up, a stress relief force is generated. The wall rock whichhas to take up the stress relief is the major bearing structure. Supporting structureswhich strengthen the strength of wall rock and take up part of the stress relief work asminor bearing structure. Different classification methods of the wall rock onlyanalyze the bearing capacity qualitatively, quantitive analysis of the bearing capacityis not done yet. In this thesis, by taking advantage of strength reduction method andthe stress response status under every reduction factor, the concept of equivalentstrength is proposed and the quantitive analysis of the bearing capacity of the wallrock comes ture. By proposing mechanical principle for different supporting structurethe bearing capacity of the major bearing structure and the minor bearing structure iscalculated. At last, in this paper, the bearing capacity of different supporting solutionsis analyzed.(1) The computational theory for supporting structure has gone through severalstages such as rigid structure, reliant structure, continuous media. The way peopleperceive the mechanical action of wall rock also transforms from the view that wallrock is the origin of stress to that it is also bearing structure. Mind of the supportingdesign is also changed:traditional supporting design method is based on structuralmechanics and contemporary supporting design method advocates to increase thebearing capacity by improving the strength of the wall rock.(2) The New Austrian Tunnelling Method is representative of contemporarystructural design principles. But the New Austrian Tunnelling Method is still based onwall rock classification and the bearing capacity of major bearing structure and theminor bearing structure hasn’t been analyzed quantitively. In this thesis, this questionis answered.(3) According to the equivalent strength concept proposed in this thesis, afteranalyzed the difference of the equivalent strength increasing amo unt under differentsupporting structures,it shows that the anchor brace’s effect of reducing theconvergence displacement of the wall rock is not significant while it improves theequivalent strength to the wall rock greatly. Spray-up brace is useful for reducing thedisplacement convergence but it does not increase the equivalent strength well. So, itis suggested that anchor brace should be used majorly. By using concept of equivalentstrength the bearing capacity of wall rocks and different supporting structure is analyzed quantitively. and a new ideas for designing supporting structures isproposed.