| The Station is located the middle reaches of Jinsha River which is seated at the junction of Diqing Prefecture and Lijiang City of Yunnan Province. Mainly rock mass in the system of Devonian phyllite, slate and phyllite folder crystalline limestone. To meet the requirements of hydraulic layout, excavation of diversion tunnel exit height of 300m, slope ratio of 1:0.75, while the lower part of slope excavation of seven needed diversion tunnel, So high and steep slope stability phyllite what? Excavation of diversion tunnel on the slope stability is their impact? Engineering design sector as the key technical issues of concern. Paper solve these problems, the investigation of diversion tunnel at the scene of rock mass slope of the outlet structure characteristics, and indoor rock on an experimental basis, on the Phyllite Body of the microstructure, physical and mechanical properties were studied. Combination of structural characteristics of rock slope analysis of the slope deformation and failure modes possible, by numerical simulation of the excavation slope stability and the tunnel excavation on the slope stability analysis. The key contents and conclusions are as follows:(1) The field geological survey shows that rock structure of the overall slope are generally belongs to the mosaic structure which structural planes are mainlyâ…£andâ…¤level. Theâ…£level structural planes are mainly including to NE steep angle structural plans and to NW medium angle structural plans, andâ…¤level structural planes are original structural plans which are quartz foliation developped in phyllite and foliation plane developped in sericite.(2) The results of thin section shows that minerals in phyllite are mainly contained quartz, chlorite-sericite and carbonate. To a certain extent, the micro-structural characteristics of phyllite appears micro-fracture phenomenon on micro soft rocks. And laboratory test shows that phyllite is significantly anisotropy and has little changed in cohesion, but there is a big difference on internal friction angle.(3) Through analysis on rock structure characteristics of the slope, to determine the main factors on slope stability and possible slope failure modes. There are including shallow slip-crack and deformation failure, deep slip-pressure crack failure. Based on qualitative analysis, by numerical simulation and rigid body limit equilibrium to analysis situations of slope stability. Slope stability is good in natural conditions and it is less likely overall instability. The largest part of total displacement is located on the top of the slope surface after excavation, but on the top of the slope which along with the part of layer interface between crystalline limestone and phyllite have the possibility to occured local instability in the rain and earthquake conditions.(4) Dealing with slope stability analysis of slope-cavern combination system on excavation indicates that the influence on slope stability is very limited for small spacing and small diameter of diversion tunnel excavation, and the changed place of stress and strain are mainly concentrated in the 6 times hole diameter of the surrounding rock mass. The deformation influenced by the excavation that the position is on the general cavity export. |
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