Fluid-solid Couplin Analysis Of An Earth-rock Fill Dam Considering The Wall Earth Contact Surface

Rock fill dam is one of the main types of dam.Affected by dam material and upstream reservoir water level,seepage damage is easy to occur.Soil,as the main component material of rock fill dam,changes in pore water pressure lead to changes in effective stress under the action of water flow.At the same time,the flow in soil will have a reaction on the fluid volume,while the traditional method for the stability calculation of rockfill dam is usually carried out separately by seepage field and stress fieldthe safety of downstream lives and material properties,and causing inestimable losses.Therefore,it is of theoretical and practical value to analyze the fluid-solid couplin of rock fill dams.In the background of the research on Xiaolangdi earth dam project,this paper was based on the monitoring data of soil pressure gauge and osmotic pressure gauge arranged for the earth-rock dam of the project,The measured and monitored results obtained from the project are analyzed.At the same time,the typical section of the dam was selected to establish a quasi-three-dimensional numerical model,and the influence of the downstream solid couplin of highest water level on recordsl action on the dam was considered in FLAC3D software.The analysis draws the following main conclusions:(1)The paper studies the contact surface between the concrete cutoff wall and the surrounding soil,and finds that:①The vertical displacement of diaphragm wall and soil decreases first and then increases.②The sedimentation of the cutoff wall is decreasing constantly,but the settlement of the top of the wall changes little,which is no more than 1cm.③The maximum horizontal displacement of the whole wall soil contact surface and surrounding soil overall tends to increase.After reaching the initial shear stiffness of the contact surface,the maximum horizontal displacement of the wall soil contact surface and surrounding soil increases gently.④When the tangential stiffness of the initial setting is not reached,the tangential stiffness of the contact surface increases tenfold,resulting in a significant decrease in the vertical stress change.Until the tangential stiffness of the initial setting is reached,there are sudden change point and reduction of the vertical stress change revealed in the whole wall soil system curve chart.⑤By comparing the number of iterative steps in the numerical calculation of different tangential stiffness schemes,it was found that the tangential stiffness of contact surface increased by 10 times,leading to an exponential increase in the number of iterative steps.(2)Under the action of typical water level,the whole simulated earth and rock dam body produces large post-construction deformation.The results of all stress cloud maps show that the stress distribution in the core wall presents obvious arch effect.When the hydraulic head passes through the concrete cutoff wall,the permeability coefficient of the wall material is small,which leads to the obvious drop of the hydraulic head,namely,producing hydraulic gradient.The pore water pressure inside the core wall is obviously greater than that under the action of upstream reservoir water level.The pore water pressure of P115,P116 and P117 was quantitatively analyzed.The pore water pressure at this point increased first and then decreased due to fluid-solid couplin,and the maximum.pore pressure value was basically equal to the water level of the upstream reservoir,while the pore water pressure of P116 and P117 was higher than the pore water pressure of the upstream reservoir,which was similar to the measured data.