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Earth-rock dam has the advantages of simple construction, low cost, strong adaptability for geological and topographical conditions etc. It is not only the water conservancy and Hydropower Engineering important type of dam,but also the largest number of dam type so far. With the increase of earth-rock dam height, the arch effect caused by hidden dangers is highlight, only considering the seepage analysis and stability has been unable to meet the requirements of the safe operation of the dam, the dam, especially the anti-seepage body stress and strain was highly attention in academic and engineering circles, study on the arch effect because of its importance has attracted more and more attention.The dam shell material of rockfill dam with core wall has strong permeability, compression characteristics of small, large deformation modulus, while the heart wall material islower permeability coefficient, low strength, high compressibility, modulus of deformation small, differences between the two kinds of material properties result to uneven displacement and settlement,so it has a greater shear deformation at the contact surface, resulting in a certain range of soil arching effect. Arch effect reduces the vertical wall stress, this will significantly reduce the heart wall density and bending strength, that will cause harm to the safety operation of the dam.On the basis of comparative analysis, select the application time is long, experience more, the experimental data is easy to collect the Duncan-Chang model, constitutive model of soil arching effect as research. Application of APDL interface language will Duncan Chang model successfully introduced ANSYS, two times of development on the software platform, and realized the hierarchical construction of dam numerical simulation function. Soil index to the three axle shear tests such as the basic data, simulation analysis on slope, Poisson’s ratio, height changes, stress distribution of the core wall, studied the impact of the three main parameters of arch effect on the core wall of δy/γh..The results show that:the Poisson’s ratio, δy/γh The larger the value, the weaker the core wall arching effect; smaller the slope, σy/γh The larger the value, the weaker the core wall arching effect; higher the dam height, σy/γh value the smaller the core wall of the arch, the stronger the effect. The core wall dam of the of in Yunnan Chuxiong Lippi Chad reservoir49m trial, consistent with the conclusions of the relevant parameters and dam safety appraisal. The arching effect obtained at the Institute of this article formation mechanism, arching effect simulation method has a certain reference value for subsequent research and similar projects.
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