Stress And Deformation Of Liujiagou Faced Rockfill Dam During Design And Storage Periods

Recent years,concrete face earth-rock dam with its convenient construction,good stability,easy to adapt to different terrain environment and other advantages,more and more people was favored by more and more designers of the hydropower project.Whether the dam type was applicable depends on the deformation control of the dam,which was also the key to the design.In addition,the cracking of concrete face slab and the seepage of the dam also seriously restricted the popularization and application of the concrete face earth-rock dam.Stress and deformation of the face plate and toe plate had a close relationship with dam deformation.Panel was under temperature load would be produced a large tensile force and may cause cracking.Therefore,the study of the cracking of the slab under the action of temperature stress had important significance for the face earth-rock dam.This paper took Chongqing Wuxi Liujiagou CFRD as an example.On the basis of the selection of dam site and dam design,the finite element analysis method of operation of the dam stress and deformation were calculated and analyzed.The stress distribution of the dam body and the panel under the coupling action of temperature and stress was studied.The possibility of cracking of the panel was discussed.The main work and results were as follows:On the analysis of the comparison of topographic and geological conditions,reservoir comprehensive utilization of capacity of storage requirements,project layout and conditions,and other factors,and put forward the scheme of lower dam site.The selected site was close to the dam project in the project investment.But there were obvious advantages in dam foundation and hydrogeological conditions of karst,the shoulder of dam foundation and abutment seepage control project investment and reliability,and reservoir neighbor Valley seepage reservoir conditions.According to the related standards,the selected scheme for the dam of dam design,included design section,dam zoning and panel of toe slab design.The dam type for concrete face earth-rock dam was recommended.The material from the face of the dam was the cushion layer,the transition zone,the main rockfill area,the sub-rockfill area,the special cushion layer and the downstream rockfill dam.The width was 7m,length of dam axis was 258 m,most dam height was 84 m,the crest elevation was 460 m,upstream and downstream dam slope were 1:1.4.In view of all kinds of loads acting on the dam during operation,such as gravity,hydrostatic pressure and so on,the simulation and analysis were carried out to analyze the stress and deformation characteristics of the dam under different working conditions.The analysis suggested that the normal high water level when the maximum settlement 4.77 cm,horizontal displacement maximum 8.45cm;dam should force concentrated in dam site and in the normal high water level maximum for 1.65 MPa;dam minor principal stress concentration in the dam and foundation,the flood limit water level minimum-0.24 MPa.The main stress area did not appear tensile stress and the condition of principal stress could meet the tensile strength requirements.During the operation period,the panel was mainly subjected to compressive stress along the direction of the dam slope,but there was tensile stress at the bottom of the panel.The temperature field distribution under the influence of temperature and the temperature of reservoir water and the stress distribution of the slab under the temperature load were studied by the method of temperature stress coupling calculation.The results showed that temperature field of dam body changed with the change of environment temperature,the distribution of stress field of dam was affected by the way of temperature load,and then changed the stress and deformation of the toe plate of the panel.From the panel tensile stress distribution,temperature cracks may be generated in the lower part of the panel;from the time point of view,the lowest environmental temperature in January to produce the maximum tensile stress.If there was a similar cold wave of low temperature of extreme weather,we needed to focus on monitoring.