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Experimental Study and Application on Permeability Characteristics of Riverbed Sandy Pebble Media

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Tutor: FanGuiSheng
School: Taiyuan University of Technology
Course: Environmental Engineering
Keywords: sandy pebble medium,osmotic coefficient,characteristics of grainsize,forecasting
CLC: TV139.1
Type: PhD thesis
Year:  2013
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Abstract:
This is a problem of high sediment of Yellow River water, which is influence of the area surface water resources development and utilization. However, using artificial filter bed with drainage for getting water can meet the needs of both water quality and quantity by manual adjustments. This getting water means has a promotion and application prospects, which key to success about getting water is how to reasonably determine the body type and structure of filter bed in the technology.Article attempt with the indoor large scale physical model experiment about original state sandy pebble medium of the Yellow River beach liulin, anglicizing of different shapes and dimensions boulders influence on the penetration ability of sandy pebble medium, building the infiltration model about the sand pebble medium under the condition of existing boulders; Then based on the permeability coefficient test of different graded sand pebble medium, analysis of the factors and rules about affecting the permeability coefficient from the perspective of the characteristic particle size index, setting up the linear and nonlinear prediction model with the permeability coefficient by predicting characteristic particle size parameters; Finally combined type of different sandy pebble to high water containing sand filtering effect experiment analysis, proposed the structure of filter layer and supporting layer, which recommended by artificial filter bed of Yellow River beach, its research results can provide technical reference for filter bed engineering construction about getting the high containing sand water beside the river in Shanxi Province and even the whole country.The results show that:(1) the critical point of influence Boulders to sandy pebble medium seepage characteristics is0.177, when seepage gradient is greater than this value, the effect is more and more significant, or no impact conversely. the shape, sectional area and volume of boulders all have different influence on the osmotic coefficient of sand pebble medium, the flow interface more coarse, or the larger the cross-sectional area or volume, the greater the filtrational resistance produce, the smaller the porous flow; the sandy pebble medium seepage model can be described by quadratic polynomial under the condition of boulders exist.(2)in the single grade group case, with the decrease of the sandy pebble medium size, the osmotic coefficient of sand pebble medium decreased gradually, and the osmotic coefficient is affected by water head is smaller; to different graded sandy pebble medium, the changes of osmotic coefficient associated with sandy pebble grain size characteristics index, this index including effective particle size, confine particle size, nonuniform coefficient and coefficient of curvature. Only under the condition of when the other parameters give a range, the change rule of osmotic coefficient as a certain parameter change is determined; Finally, the best sandy pebble grain size distribution and structure was selected by an experimental study.(3) Through a lot of different graded sandy pebble medium permeability test data analysis, it be found that the osmotic coefficient can be forecasted by the size characteristics index; then linear and nonlinear simulation model with effective particle size, confine particle size, nonuniform coefficient and coefficient of curvature as independent variable were erected, The average relative error model predicted and the measured values were12.4%and26.2%respectively, it means using multivariate linear regression model for the osmotic coefficient sand pebble prediction had higher accuracy.(4)it Found that in technology parameters test of sandy pebble medium artificial bed filtration body, taken0.25¡«1.0mm medium of fine particles and the geotextile composite layer as main filter layer, same particle size medium layered filling as support layer,the water and water yield both meet the requirements, and facilitating silt machinery cleaning and water cleaning, mud resistance, keeping permeability, good cleaning effect, is a kind of filter body type that is worth to recommend.There are some innovation in this paper, for example, sandy pebble medium model, predict permeability coefficient by particle size characteristics index and the yellow river artificial filter bed type, etc. This study put forward the way of artificial water infiltration bed which can effectively utilize yellow river water which contain sand, is a efficient path to ease the contradiction between supply and demand of water resources, the research only carried out in indoor laboratory and needs to be further perfect and supplement in the engineering practice and the accuracy of model prediction.
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