The Study On Deformation Mechanismoftianbacun Accumulation On Tianhuabanhydropower Station Andstability Evaluation

Tianbacun accumulation is located in the left reservoir of Tianhuabanhydropower station, which is1.0km away from built dam.The stability ofaccumulation is essential to Tianhuaban hydropower station. According to theseconditions, the article describes engineering geological conditions of Tianbacunaccumulation and analysis the deformation characteristics of theaccumulation.According to the monitoring data, the deformation mechanism isstudied.The stability of the accumulation is evaluated by the limit equilibrium methodand strength reduction method.The main work and achievements are as follows:1.Through investigating the engineering geological condition on borehole dataand landform characteristics, the accumulation is divided by three zones.I area isdivided by four areas and II area is divided by three areas.2.Throughanalyzingfive monitoring section curve, the characteristics of depositare studied.The results show that firstly I area has a direct relationship with watermovement, secondly there is a typical creep deformation characteristic, and thirdlydeformation of accumulation is gradually stabilized.3.The stability of accumulation is evalued by limit equilibrium method.Theresults show two aspects.Firstly, on the normal water level condition, the stability ofI-1and I-4area is between0.95~1.09, which is in critical condition.The safetycoefficience of I-2and I-3area is between1.04~1.71, which is in safetycondition.Secondly, on the water level fluctuation condition, the stability of I-1andI-4areas is in critical condition and the stability of I-2and I-3areas is in safetycondition.4.The stability of accumulation is evalued by strength reduction method.Firstly,on the normal water level condition, the stability of I-1area is1.1and the stability ofI-4area is1.15; secondly, on the water level fluctuation condition, the stability of I-1area is1.05and the stability of I-4area is1.10.