Experimental Study On Filter Material Of Sand Dam

Sand dam is a kind of earth-rock dam,which is filled with fine sand,and has been widely used in the northwest of China.It has positive significance to alleviate the water contradiction in these areas and promote the local economic development.However,because of the lack of natural gravel in these areas,the selection of filter material is a key problem.The development and popularization of composite geotextile provide a way to solve this problem,but the sand dam with composite geotextile as filter material appears clogging phenomenon.How to select the appropriate filter material for sand dam according to the principle of selecting the nearest material is very important in the existing conditions.Based on a large number of reading literatures,this paper systematically summarizes the research status of composite geotextile filter material and gravel filter material at home and abroad.We conduct equivalent aperture experiment,seepage experiment and clogging experiment to explore the failure of composite geotextile preliminarily by selecting two kinds of composite geotextiles commonly used in the area of sand dam situated taking Li jialiang reservoir as an example.To research the feasibility of artificial sand gravel anti-filter materil in areas sand dam situated,we conduct seepage experiment,piping experiment and contacting loss experiment to adjust the gradation range of gravel filter material through the theoretical calculation and actual selection.We selecte the suited one and give some suggestion by comparing composite geotextile filter material and gravel filter material.The main research contents and conclusions follows:(1)To set out the soil conservation,water permeability and prevention clogging of two kinds of composite geotextiles selected.Two kinds of composite geotextiles selected can meet requirements of soil conservstion,water permeability according to equivalent aperture experiment,vertical infiltration experiment.The two composite geotextile silt up in a short time,and the upper envelope soil-composite geotextile system more clogger than the average and lower envelope soil-composite geotextile system by analyzing experiment data based on clogging experiment of six groups of soil-composite geotextile system.Most of the protected soil material gradation is concentrated on fine and average envelope indicating that the composite geotextile as filter material in sand dam has certain risk.(2)For the gravel filter material,the first fiter sand selects the Yellow river sand in Yulin city,the second sand gravel selects the mixture of the Yellow rover sand and artificial gravel by theoretical calculation and actual selection.The samples can meet the requirements of water permeability by permeability experiment.It's known that the piping failure will occur when the soil is protected with filter material through the piping experiment.It's known that infiltration and seepage failure will not occur,the filter material can meet the requirements of filter and drainage.(3)It is suggested that artificial gravel and natural sand should be mixed according to the ratio of 2: 1 in the area of no suitable natural gravel filter.