Study Of Deformation Of Asphalt Concrete Core-wall Rockfill Dam Builted On Deep Cover Layer

With excellent dam site gradually reduce, dam project is now having to build on some deep cover layers like tributary of dadu river?shelter-forest of jinsha river?shelter-forest of nu river?some rivers in Xinjiang and Tibet which are in complicated geological conditions.Rocks and soil in deep cover layer are discontinuity,and geotechnical properties have great changes in both horizontal and vertical directions.Deep cover layer caused complex,and physical and mechanical properties also have larger nonuniformity,so it many face to much more new problems and challenges of the building on deep cover layer. Now,asphalt concrete core-wall rockfill dam stands out from the crowd because it could well adapt to the complex dam foundation.Rockfill dam's deformation and stress and strain in covering problem is an important factor on rockfill dam safety, is also the most concern of the design phase.For the designing of dam in complex geological conditions,3D numerical simulation is one of the most useful method which could make the best use of limited data,and also it is a valuable project to study.Yele dam is not only the most difficult dam with highest asphalt concrete core wall which was build on the deepest cover layer in China,but also the dam of various monitoring method and abundant monitoring data.And there is few people to compare with more than a decade of monitoring data and 3D numerical simulation results to check and improve the calculate means.In the paper, on the basis of learning large of relevant materials at home and abroad,rely on Yele dam,take 3D numerical simulation to the dam of Duncan-Chang nonlinear model and Nanjing Hydraulic Research Institue double yield model respectively. Calculated results show that both are roughly similar, but the deformation of Duncan-Chang model is larger.campare to the monitor data of Yele dam from 2004 to 2014, we find that the calculate results of neither the two models are in full accord to the monitor data,espically the settlement of 3D numerical simulation is much less than the monitor data, but Duncan-Chang model is more close to.In order to find out the reasons of errors occurring in calculation results with the measured results,this paper studied the rationality of the constitutive model, characteristic of asphalt materials, parameter values, etc.analysised the why the differences occurred,and put forward a more reasonable calculation method.In this paper, the main research contents and results are as follows:(1) Systematically introduces Duncan-Chang nonlinear model and Nanjing Hydraulic Research Institue double yield model which could well describe the deformation of rockfill dam.Compared theoretically with the two models;(2) After the studying of the geological conditions of the dam site,wo found that dam foundation is serious asymmetry,bedrock exposes in the left bank but on the right side,the thickness of the cover layer is more than 420 meters.The covering could be subdivided into five layers,and layer II and layer IV are relative water-resistied.We could obtain the parameters by the triaxial test;(3) Developmented Duncan-Chang nonlinear model and Nanjing Hydraulic Research Institue double yield model by Visual Studio in F1AC3D software;(4) Took the use of parameters by triaxial test,constructed 3D model of the dam,and took the 3D numerical simulation of the dam by the two models respectively.the result showed that the max horizontal displacement of dam are 39.8cm(Duncan-chang) and 29.1 cm(Nanjing), the max settlement are 127.9cm(Duncan-chang) and 92.7 cm(Nanjing), local appear stress concentration phenomenon, but are in the range of security, Duncan-chang model simulation results is larger than the other;(5)Analyzed the monitor data of Yele dam from 2004 to 2014,excluded error data, the result of the dam horizontal displacement is 34.3 cm, settlement is 160.6 cm, horizontal displacement is similar simulation results, the subsidence value is much larger than the simulation value, in other words, the simulation results is unsafe, but Duncan-chang model is more close to the result;(6) Researched and analyzied the Limitations of the two constitutive model theriself, at the same time analyzied the asphalt concrete material stress strain curve, found that the simulation of dam body is more appropriate by using Duncan-Chang model, but for the asphalt concrete core wall just Nanjing Hydraulic Research Institue double yield model is more reasonable;(7)Study the Sensitivity of the model parameters,found that the parameters sensitivity became smaller in proper order according to"?"?"Rf"?"c"?"K"?"F"?"n"?"G"?"D",and among them, "?"?"Rf"?"c"are easy to get in triaxial test with little error, but the "K" is easy to be large error because of the range precision prone. We could get more close to the actual parameters by inversion.(8) Take the use of combination of the two models, and the inversion parameters, play the 3D numerical calculation of the dam again, horizontal displacement is 35.2cm and settlement is 163.6cm, the final result is more close to the actual value.