| Seepage failure is a main reason of the hydraulic structure accidents such as embankment and earth-rock dam.The effect of earth-rock dam is Water storage,As the reservoir water level rises,there will be a hydraulic pressure difference between the dam body and the foundation soil,which may cause seepage damage.Therefore,when designing earth-rock dams,we must not only meet the requirements for stability,but also take measures to prevent the occurrence of infiltration and destruction,meet the requirements of permeation stability,and ensure the safe operation of earth-rock dams.Filtering layer is the most effective measure to prevent the seepage failure,Set up it at the outlet of the seepage to filter soil and reduce the pressure of water,so as to achieve the purpose of osmotic stability.In the natural world,there are many types of soil and the performance varies greatly.How to make the filter layer both economical and able to reflect the characteristics of the soil to be protected,and ensure the stability of the seepage,the use of proper filter layer criteria is crucial.Otherwise it will cause the overall failure of the filter function.The paper which is based on the financial supports from the National Natural Science Foundation of China “Movable porous media phase transition mechanism and transition-osmotic-stress coupling model of piping for granular porous media based on random method(51409129)”,through indoor experiment,the occurrence and development process of the seepage failure of granular soil in the soil-filter system was studied.Based on experimental research,The effects of factors such as inter-layer coefficient,grain size distribution,hydraulic conditions and layer-thickness ratio on the migration of fine-grained soil particles were investigated.The paper research results are as follows:(1)Based on the theory of the Terzaghi filter layer,the self-developed large seepage instrument was used to study the influence of grain size distribution of the soil to be protected and filter on the hydraulic migration of the protected soil under gradient water flow.The critical hydraulic gradients,and the changes in flow rates and permeability coefficients during the experimental process were studied,Thus,the influencing factors of the effectiveness of the protected soil by the soil-filter system are explored.(2)The effects of two kinds of hydraulic conditions on the migration of the protected soil are investigated by means of the uniform variation and the cyclical changes of of the water head difference.Study the effects of different hydraulic conditions on the hydraulic transport and critical conditions of the protected soil particles.(3)Based on the failure and effective base-filter system,the critical hydraulic gradient of the base-filter system with different filter thicknesses was compared to observe the changes in the movement state of the protected soil.To study the effect of layer thickness ratio on the hydraulic migration of protected soil particles in the two systems,the relationship between the layer thickness ratio and the effectiveness of filter was explored. |
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