| The natural slope of Rumei Hydropower Station is almost thousands of meters，while the engineering slope could reach up to hundreds of meters. The stability problemof high slopes is complex, when the complex geological structure, regionalmetamorphism, rivers-incising, high-cold and freeze-thawing erosion, strong unloadingand weathering happen as well as other poor weather conditions. Those stabilityproblems of high slopes are manifested in the local instability problem of the superficiallayer unloading rock mass, and the stability problem in the deep layer of loose rockmass with a certain scale of unloading and weathering rupture. Moreover, with respectto the differences of basic geological structures in each part, instability failure modesshow as plane sliding, dump deformation, wedge sliding and the coexistence of multiplefailure modes. Even in the same kind of geological structure, the slope instability modesand their scopes still have significant differences for different excavation shapes andcutting depth in various parts. Therefore, when constructing high dams and largereservoirs in such complicated deep valley areas, the stability problems of high slopesand their treatment cannot be avoided, which may be the key point for the damconstruction and investment.The systematic study on the slope of Rumei Hydropower Station, includingregional geology, slope lithological characters, geological structures and rock massweathering and unloading characteristics, is employed in this paper. Firstly, boundaryconditions of instability and failure modes of the slope were proposed, and then aneffective geomechanics mathematical model was established. Secondly, the paperadopted the limit equilibrium method and the elastoplastic finite element method toanalyze and calculate the stability of the slope. Finally, the stability assessment of theslope was carried out, and preliminary reinforce methods of the slope were alsosuggested in this paper. The main conclusions are as follows:(1) There are several mainpossible failure modes of the slope of Rumei hydropower station, such as:①internal orbottom interface slip along the cataclastic rock mass;②Unloading fissures along thedimensions of the sliding surface or stream;③wedge sliding damage;④dumpingdamage.(2) the limit equilibrium method and elastoplastic finite element method for slope stability analysis and calculation is used by the right dam abutment excavationslope (B2-B2section), and the plastic zones nearly have phenomenon of linking up. Theslope safety factor does not meet the specification requirements. The outside slidingarea is mainly excavation area for the upper loose cataclastic rock mass slope, andreinforcement measures should be taken for the slope. The likelihood of hole slippage ofNo.SL18crushing loose rock slope along contact surface didn’t seem much, but it’slikely to produce slippage in a certain range inside the crushing rock. so the slope needto be reinforced.(3) Thorough the limit equilibrium method and the elastoplastic finiteelement method analysis, the result of the two methods appears to follow the samediscipline. But an acceptable different between the safe factors exits, because thedifferent assumption of the interaction between rock lump.(4) According to the slopesteady analysis: the excavation slope at right bank is to be deal with the methodcombines shallow shotcrete-bolt support and pre-stress cable; And the broken loose rockwill be strength by deep pre-stressed cable and flexible active protection net.The study of this paper cannot only effectively solve the engineering practicalproblems of the high slope in Rumei Hydropower Project, but also provide the reliabletechnical theoretical support and the reasonable governance program, so as to achievethe purpose of the stability and safety of the slope and feasible treatment measures, andsave the project investment. |
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