Study On Stability Of The Quasi-bedded And Counter-tilt Rock Slope In Right Bank Diversion Tunnel Inlets Of Nuozhadu Hydropower Station

Generally, there is bedded (Quasi-bedded) structure characteristic in sedimentary rock and extrusive rock., but researching find that it developpreponderant discontinuity, same as the bed rock structure in block rock(intrusive rock). The Quasi-bedded and counter-tilt rock slope that tend towards of the slope are parallel with the preponderant discontinuity or terrane's, and direction of the discontinuity are different from the slope's. Some engineering practices show that the failure of Quasi-bedded and counter-tilt rock slope that has many dangerous result such as invisibility and sudden, high speed and calamitious. So people was realized gradually that the researching of Quasi-bedded and counter-tilt rock slope are strengthened needly in important engineering.This paper is based on a great lot of geological investigations of Quasi-bedded and counter-tilt rock slope right bank Diversion Tunnel inlets in NuoZaDu Hydropower Project on Lancang River of Yunnan. Meanwhile, the paper gives a detailed analysis of rock mass structure characteristic and slope structure characteristic. Based on this, Based on the failure traces of slope during excavation, the mechanism of deformation and the mode of deformation is analyzed, meanwhile, the mode of deformation and failure is generalized. Then the stability of high slope after excavation is evaluated reasonable. The key contents and conclusions are as follows:1. Based upon excavation of slope, the rock mass structure of slope right bank Diversion Tunnel inlets is researched completely. The researching consists of the different discontinuity, the geological classification of discontinuity, the investigation of different discontinuity, especially the counter-tilt high-angle dip discontinuity is done. At last, the mode of rock mass structure is established.2. Based on the failure traces of slope during excavation, considering the characteristic of rock mass structure and slope structure, the mechanism of deformation and the mode of deformation is analyzed, meanwhile, the mode of deformation and failure is generalized. According to the characteristic of deformation, the support measure is advised.3. By the limit equilibrium theory, the stability of excavating slope right bank Diversion Tunnel inlets is calculated and analyzed.4. By UDEC DEM numerical simulation, the different characteristic and combination of discontinuity (â…¢,â…£) is accounted especially, to simulate the operation of rock mass structure during exaction, meanwhile, the characteristic and rules of deformation mode is researched. In addition, with the actual conditions, By FLAC^3D numerical simulation, to simulate and compute the stress-strain of the slope, In addition, by the monitoring information, to verify the result of simulation, meanwhile, the stability of slope is analyzed.