Finite Element Analysis Of Stress And Deformation On Earth Dam Heightening Due To ANSYS

Earth dam is one kind of ancient hydraulic engineering structure, has the advantage of simple structure and low cost, it can adapt natural condition easily and have strong resistance against earthquake thus was constructed massively. There are more than 80000 dams in our country now, these projects once had played the tremendous role in the national economy, but most of them were built in the last century 50-60 ages. Because of the poor economical and technical condition the reservoir designing standard was somewhat low in the limit of construct condition. Most of them were on the one hand surveying, designing, on the other hand constructing which called"three being projects". Majority of the reservoir were sediment seriously, whose storage capacity reduced greatly after 30 years serving .It can't play its effective role normally, moreover was working at a state of illness for a long time. In order to remedy this disadvantageous condition, in reinforcing design we always reinforce the dams by raising them to a suitable level in order to maintain or increase the storage capacity and raise reservoir own economic efficiency and the social efficiency.This paper summarizes the dam reinforcement design experience, comparing dam heightening way and propose a new way of earth dam heightening that is add new dam on the upstream silt surface which is suitable for the Loess Highlands area where the soil erosion is more serious. Based on typical project example the author use finite element software to simulate the construction process and compare the strain and stress changes before and after dam raising then conclude a role about the stress and deformation changes when raising the dam and show the perturbation to the original dam is not big. There is a small increase in the strain and displacement when the dam first store water which show that the dam have better stability after raised and verify that raising dam on the upstream silt surface is feasible. Also point out that the weak part of the dam after raised is located in the combination of the silt, the new dam and the old dam. We should pay special attention to strengthening the weak parts in dam reinforcement design and construction in order to prevent slip destruction and seepage failure occurred along the weak side of the dam.Compare with various constitutive models, the author choose Duncan-Chang E~V model as soil constitutive model for stress and strain analysis and analysis the sensitivity of each model parameters. Using the APDL language re-develop ANSYS software and write corresponding ANSYS code for further calculate. Simulate the layered RCC construction process by using element birth and death command and restart function. Use the midpoint load incremental method for the nonlinear finite element calculations and write corresponding post-processing code for rip fracture and shear amendment which makes the results more reliable and the simulation more accurate. This article verified the reliability of this procedure by typical project examples, the results show this process is reliable and there is a little difference between the calculated result and the measured ones. The stress and deformation rules summarized in this paper can be used in similar project and may provide reference for the designing and construction.