Quantitative Research Methods Of Effects Of Valley Topography On Stress And Displacement Properties Of CFRD

Dozens of high CFRD have been built in deep valley since 1985 in China and people have accumulated rich experience of CFRD in canyon area.But because of the complexity in engineering of CFRD,the related theoretical study still lags behind the engineering application.It is a meanful work to rich the design theory,deformation characteristic research and engineering improvement of CFRD in canyon area.Due to the effects of rock size and other factors affect the stress and deformation of the dam at the same time,the effect of Valley topography is difficult to separate directly.The finite element method has the advantage on analyzing the single factor compared with the field test and the model test.So the finite element method was used to study the influence of valley topography on the stress deformation characteristics of CFRD.The main results are as follows:The paper introduced the project practice and problems of CFRD in canyon area.A new valley topography parameter has been given in this paper.This new parameter is described by using valley width coefficient,valley slope coefficient and valley asymmetry coefficient three parts.The valley width coefficient was be used to describe the width of vally.The valley slope coefficient was be used to describe the steep of vally and the valley asymmetry coefficient was be used to describe the asymmetry of vally.A quantitative criterion for distinguishing valley width,steep slope and river valley symmetry is given by using of finite element method.Then,using Finite Element Analysis to analysis the effects of quantification of valley topography on stress and deformation of CFRD.According to the results,a Classification of CFRD based on the effect of valley topography has been given.A valley influence coefficient has been given to classify the effect level.Using this valley influence coefficient to classified the CFRD which had been built in the past,with good results.The formation mechanism of soil arching effect which happened in the bottom of dam was been studied.The results show that the narrow valley and uneven settlement are the main reason to produce soil arching effect.The redistribution of stress alone vertical direction and horizontal direction are the mecnanical mechanism of soil arching effect.Put forward a new method to discover the location of the reasonable axis of arch and using this method to study the influence of valley width and valley slope on arch effect,for adopting engineering measures to weaken the negative impact of the arch effect.The Steep valley slope is the main reason to rise the axial tensile stress of concrete face panel.The arched concrete face rockfill dam was used to reduce the the panel axial tensile stress of concrete face panel and the finite element calculation results show that the effect is good.According to the results,we suggest the height of the arch distance is 0.015-0.025 times to the length of the dam axis.The statics and dynamic response properties under slanted topography condition were to be analyzed by using the equivalent viscoelastic model.The inclined dam foundation could influence the dynamic response properties of CFRD,the maximum dynamic displacement towards the river inclined dam foundation mainly include the broken of anti-seepage system and the downstream dam slope instability.The maximum anti-seismic capability of the dam is 0.5g-0.58 g.