Study On Stress And Deformation Of Earth-rock Dam Based On The Spatial Variability Of Mechanical Parameters Of Dam Materials

Water conservancy project is one of the indispensable infrastructures in modern society.It plays an important role in flood control,power generation,water supply and irrigation.It plays an important role in promoting economic and social development and brings huge economic and social benefits.Considering a variety of factors,such as the existing technical and economic conditions,earth-rock dams are still the main dam type used in the field of water conservancy projects.However,most of these dams are located in western high-altitude areas such as Sichuan-Yunnan-Xinzang.These areas have high mountains and deep valleys,complex terrain conditions,high seismic intensity,and inconvenient transportation.Therefore,the safety problem of earth-rock dam is particularly important,and the deformation of dam body is one of the core problems in the safety evaluation of earth-rock dam.At present,numerical calculation is the main means of earth-rock dam deformation research and safety evaluation.According to the actual situation of field construction and engineering data,the lithology,weathering degree and filling quality of earth-rock materials in the same dam material partition of earth-rock dam are not uniform,which leads to the difference of material mechanical parameters in different positions of the same dam material partition in space.This shows that the mechanical parameters of dam materials have certain spatial variability,which has an important influence on the random response of engineering structures.However,the traditional finite element numerical simulation usually uses the mechanical parameters of homogeneous earth-rock materials determined by laboratory tests to calculate,and generally cannot consider the spatial variability of mechanical properties of dam materials.There is a certain difference between the calculation results and the stress deformation behavior of the actual dam.Based on the geotechnical test results of a built earth-rock dam project,this paper introduces the spatial random field theory,adopts the research method of numerical simulation,establishes the random field calculation model of earth-rock dam construction material parameters through self-compiled program commands to carry out three-dimensional static analysis of the dam body,realizes the transformation of earth-rock dam construction material from certainty to uncertainty,and carries out the research on the influence of spatial variability of dam material mechanical parameters on the stress and deformation of earth-rock dam.In order to provide a more accurate reference for the reasonable prediction of dam deformation,the study of dam material characteristics and the design of dam material engineering,the specific work is as follows:（1）The three-dimensional model of high core wall rockfill dam is established.The Duncan-Chang E-B nonlinear elastic model which reflects the nonlinear characteristics of earth-rock dam material is used.The construction and impoundment process of earth-rock dam is simulated by self-programming commands and layered loading.The static nonlinear analysis includes the stress and deformation analysis of the dam during the completion period and the operation period.The results show that the calculation results of the stress and deformation of the earth-rock dam based on the above model are in line with the general stress and deformation law,and prepare for the subsequent calculation.（2）Based on the geotechnical test results of a built earth-rock dam project and the advanced spatial random field theory,the three-dimensional static analysis of the dam body is carried out by constructing a stationary random field.The influence of the mechanical parameters of the Duncan E-B model on the settlement and horizontal displacement of the dam body is obtained.The sensitivity of the mechanical parameters of the Duncan E-B model is studied and the sensitivity ranking is given.The results show that the parameters K_b,K among the parameters of Duncan E-B model,K_b,K andφ₀ have great influence on the deformation of dam body,among which the influence of parameter K_b is the most significant,the influence of parameter n and R_f is slightly weak,and the influence of parameter△φand m is not obvious.（3）According to the sensitivity conclusion of mechanical parameters of E-B model,the influence of spatial variability of dam materials on stress and deformation of earth-rock dam is studied.Combined with an example,the variation law and influencing factors of dam settlement,horizontal displacement and maximum principal stress after considering the spatial variability of material parameters are analyzed from the perspective of probability.Then,the maximum probability value of the numerical calculation of the earth-rock dam is compared with the numerical calculation value of the conventional earth-rock dam,and the scientific rationality of the stress deformation analysis of the earth-rock dam considering the spatial variability of the material parameters is verified.The results show that after considering the spatial variability of material parameters,the fluctuation of cloud boundary such as settlement,horizontal displacement and maximum principal stress increases,and the value is larger,that is,the numerical calculation results of conventional earth-rock dams are safe.