Coupling Analysis Of Seepage Field And Stress Field Of Cemented Sand And Gravel Dam

Cemented sand and gravel dam(CSGD)is a new type of dam developed in the 1970s.It aims to provide a more efficient construction,safe and reliable,economic and environmental protection choice for small and medium-sized reservoir dam project.At present,There are relatively few studies on it at home and abroad,especially in its seepage characteristics and stress deformation characteristics,there are still some problems to be further studied.Therefore,it is of great theoretical and practical significance to carry out orthotropic seepage analysis and coupling analysis of seepage field and stress field.In this paper,based on the characteristics of layered rolling and rising of CSGD,the orthotropic seepage characteristics of the dam are analyzed and discussed,the basic theory of seepage and the principle of finite element analysis are expounded,and the feasibility of using ABAQUS software to analyze the orthotropic seepage field of CSGD is verified with an example.Then,based on the analysis of the stress-strain characteristics of the cemented sand,gravel and rock,a suitable constitutive model is selected.Through the secondary development of the software,Duncan-Chang model is introduced into the material library,so that it can meet the needs of the finite element analysis of the stress and deformation of the CSGD.Secondly,the coupling mechanism of seepage field and stress field is discussed,and the mathematical model considering the interaction of the two fields is established.Finally,combining with the actual project of Shou Koubao dam,the seepage characteristics and stress deformation characteristics of the CSGD are revealed:(1)With the increase of the ratio of the horizontal permeability coefficient to the vertical permeability coefficient of the cemented sand gravel material,the seepage line of the dam tends to decrease due to the impervious measures adopted for the CSGD,but it is mainly reflected in the upstream side of the dam,the seepage flow of the dam and the seepage gradient behind the dam are still increasing,which is unfavorable to the seepage stability of the dam.(2)During the completion period,the horizontal and vertical displacements of the dam are distributed symmetrically along the dam axis,the horizontal displacements are gradually reduced from the upstream and downstream dam slopes to the dam axis,and the vertical settlement displacements are gradually reduced from the middle of the dam to the ground base;Under normal storage level and check flood level,the overall deformation of the dam is relatively small,and the horizontal displacement is relatively large affected by the impoundment,and the upstream side of the dam has a displacement inclined to the downstream;Under different working conditions,the stress amplitude of the dam is small,the stress level is low and the distribution is regular.The dam is generally in the compression state,and the stress value gradually increases towards the basement,and the local tensile stress appears at the upstream dam heel.(3)By comparing the calculation results of whether the coupling of seepage field and stress field is considered or not,it can be found that the horizontal and vertical displacement of the dam increases after considering the coupling effect,and the upstream displacement of the dam axis generally tends to the downstream side;the main stress value of the dam increases;the position of the seepage free surface rises slightly,and the water head contour shifts to the downstream when the coupling is not considered The elevation of the escape point rises and the seepage flow increases.It can be seen that the interaction between seepage field and stress field can not be ignored.In engineering practice,attention should be paid to the consequences of the coupling of the two fields.The research results of this paper have reference value for the actual engineering design and construction of the CSGD,and hope to provide some reference for the research of similar engineering problems.