| Stability of dam foundation is one of the main engineering geological problems ofconcrete gravity dam. The concrete gravity dam of Yagen2rd hydropower stationto bebuilt on Yalong river, it’s maximum dam height is130m, a total of15dam,and it’s larg-es foundation excavation depth is129.1m. The dam foundation rock for Yanshan is ear-ly invaded Cima cashmere rock, monzoniticgranite,and it’s rock mass structure is com-plex, with the development of a NW to partial left NWW to the structure, NE~NEE totwo groups of faults and a group of inclined upstream face. The structure of rock massof the dam foundation stability against sliding influence. Therefore, study on the Yagen2rd hydropower station’s stability against sliding, has important practical significance.In this paper, through the detailed investigation of geological environment of grav-ity dam, dam foundation rock at all levels to identify structural surface developmentand mutual relations, the geological model of dam foundation rock. Combined with theclassification of dam foundation rock mass structure, surface character classificationand the result of rock mass quality classification, selection of mechanical parameterstability of dam foundation calculation requires the. Based on this, a combination ofqualitative and quantitative methods, the dam foundation stability against sliding arestudied. The main conclusions are as follows.(1) the geological structure of the strong, but not by regional fault. The exposed be-drock of two granite. Rock mainly developed Ⅱ, Ⅲ, Ⅳ,Ⅴ grade structure, the grade IIstructure4. The dam foundation rock mass quality is very good, mainly in class Ⅱ rock,a small amount of class III rock left and right bank dam section.(2) of the gravity dam has the control significance stable structure with F16, f52and f149-9, f144-5drilling revealed, f152-2etc.. The dam foundation rock mass stru- cture form combination to deep slip appears in the2-2section, and there are two kindsof failure modes. The double surface damage to F16as the edge cracking surface,f149-9, f144-5and f152-2three structure through as the bottom surface, a single slipsurface damage as the bottom sliding surface with f149-15, f144-5and f152-2.(3) The design specification for concrete gravity dam (SL319-2005) failure modeof limit equilibrium method is recommended to two kinds of slip on the6#dam iscalculated according to the excavation,20m,28m and40m in three cases. Gravity damin normal water level (2650.00m), heavy rain and earthquake of three kinds of loadingconditions, three kinds of the excavation depth limit equilibrium calculation resultsshow that, during the excavation in the case of20m, the stability of the dam foundationslip resistance, stability coefficient is very close to the requirements of the safetysystem specification. In the excavation in the case of28m, the sliding stability ofexcavation stability coefficient is20m to high dam foundation rock excavation, in thecase of40m, dam foundation rock mass stability against sliding coefficient than thespecification requirements more stable coefficient.(4) select1-1,2-2,3-3,4-4,5-5,6-6a total of6section, the application of FLAC3Dnumerical simulation analysis. Simulation of gravity dam in the operation period ofnormal water level when subjected to hydrostatic pressure, the uplift pressure and wei-ght loading conditions, stress and strain state of dam body. The results show that, themaximum and minimum principal gravity dam stress distribution, deformation will oc-cur in the operation of small.(5) Recommended Practice for the limit equilibrium method and numericalsimulation results show that, the anti-sliding stability of gravity dams in the basiccombination and two kinds of special combination of circumstances, are stable, thesmall displacement numerical simulation. Based on the calculation of the excavationdepth comparison of different results, the recommended excavation depth is28m,which can guarantee the sliding stability of dam foundation for resistance, but also canreduce the cost. |
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