Laserfiche WebLink
<br />. <br /> <br />23 <br /> <br />representing the CDI' crosses the sieve analysis curve at a diameter slightly <br /> <br />. <br /> <br />different from 84.13 percent or 15.86 percent finer. To compensate for this <br /> <br />discrepancy, a gradation coefficient is defined as <br /> <br />G = (1/2) ( <br /> <br />D84 <br />-+ <br />050 <br /> <br />DSO <br />) <br />D16 <br /> <br />(2-9) <br /> <br />. <br /> <br />where, G = gradation coefficient, <br /> <br />D = the size of sediment for which x percent of the sample is <br />x finer. <br /> <br />. <br /> <br />When DSO and G are determined, it is possible to locate the representative <br /> <br /> <br />line on probability paper and determine the representative sizes of sediment <br /> <br />. <br /> <br />between 016 and D84' such as D35' D6S' and etc. that are utilized in <br /> <br />various equations. The method explained above is only applicable to "S" <br /> <br />normal distribution curves. <br /> <br />. <br /> <br />2.4 Forms of Bed Roughness <br /> <br />2.4.1 General <br /> <br />It is known that for flow in channels composed of sandy soils, a strong <br /> <br />. <br /> <br />physical interrelationship exists between the friction factor, the sediment <br /> <br />transport rate, and the geometric configuration assumed by the bed surface. <br /> <br />The changes in bed form result from the interaction of the flow, fluid, and <br /> <br />. <br /> <br />bed material. Thus, the resistance to flow and sediment transport are func- <br /> <br />tions of the slope and depth of the stream, the viscosity of the fluid, and <br /> <br />the size distribution of the bed material. The analysis of flow in alluvial <br /> <br />. <br /> <br />sand-bed streams is extremely complex. However, with an understanding of <br /> <br />the different type of bed forms that occur, the resistance to flow and sed- <br /> <br />iment transport associated with each bed form and how the variables of depth, <br /> <br />. <br /> <br />slope, viscosity, and etc. affect bed form, the engineer can analyze, antic- <br /> <br />ipate, eliminate, or alleviate problems that occur when working with alluvial <br /> <br />rivers and channels. <br /> <br />. <br />