| The zonal disintegration phenomenon within surrounding rocks of deep tunnels is apro-minent feature of engineering response to deep rock mass.For the zonal disintegration dete-rmines the excavation methods and support design of deep rock mass,it must be paid more attentions.Therefore,it is of great importance to conduct deep research into the surrou-nding rock deformation,the occurrence mechanism of zonal disintegration and its influenci-ng factors.By means of theorical analysis,similar material simulation,numerical simulatio-n,combined with the in.situ observations from our predecessors,some test studies are car r-ied out,they initially revealed the mechanism and the affecting factors of zonal disintegration.The main conclusions include the following aspects.The theorical analysis aspects:The theory of spatial shearing band is used to explain how the zonal disintegration oc-curs,the shearing criterion is put up with.From the view of geomechanics,the vortex s-tructure is regarded as zonal disintegration with a large scale under certain internal and e-xternal stress difference.Elastic-plastic theory,non-euclidean model is introduced to analyze-and explain the characters of zonal disintegration,the stress solution in damaged zone is developed,how the parameter of E/λ has an important effect on it is analyzed.The test study aspects:1)The property of adjacent rock layers may affect crack propagation.2)Homogeneous degree,toughness and strength of materials play an important role in-style of zonal disintegration.3)The shape of cross section has little effect on zonal disintegration as the zona disintegration occurs around the circular and square tunnel.4)There is a close relation between zonal disintegration and boundary conditions and t he unloading energy release rate.5)The zonal disintegration is a kind of space shear zone failure and the stress,p arallel to the cavity axis,is larger(far exceed the material’s compressive strength),w hich is important condition for the formation of zonal disintegrationThe numerical simulation aspects:The numerical simuation centre on space-time evolution laws of zonal disintegration,so me key results are as follows:1)The more far away from the compressing surface,the more far away from the tunn el wall,the later the surrounding rock receices the stress.2)The degree and range of each cross section along the direction of tunnel axis are different. |
