In optimal design concept, the geometric dimensions of a channel cross-section are determined in a manner to minimize the total construction costs. The Direct search optimization method by using MATALAB is used to solve the resulting channel optimization models for a specified flow rate, roughness coefficient and longitudinal slope. The developed optimization models are applied to design the round bottomed triangle channel and trapezoidal channels to convey a given design flow considering various design scenarios However, it also can be extended to other shapes of channels. This method optimizes the total construction cost by minimizing the cross-sectional area and wetted perimeter per unit length of the channel. In the present study, it is shown that for all values of side slope, the total construction cost in the round bottomed triangle cross-section are less than those of trapezoidal cross-section for the same values of discharge. This indicates that less excavation and a lining are involved and therefore implies that the round bottomed triangle cross-section is more economical than trapezoidal cross-section.
In this research the characteristics of bed material of 35km of Tigris river from Badoosh tothe end of Mosul City was studied ,nine locations were selected for sampling surface and subsurfacematerial, at each location samples are collected from left and right bank of the river. Analysis ofthese samples show that the gravel surface bed material of Tigris river had D50 equal to 33mm witha dominant size very coarse and coarse gravel with a percentage 42%, 36% , respectively, sand isalmost mislaid in this layer. The particles of surface layer had a disc shape with a percentage 51%and blade 19%, spherical 17%, and cylindrical 13%. The results show that the right bank particlesare coarser than left bank. The subsurface bed material consist of gravel and sand, the D50 of thislayer was equal to 17mm, the domain size was coarse gravel with a percentage 29% , sandpercentage in this layer was about 17%. The subsurface layer is unaffecting on any changes in flowregime because it is completely protected by gravel surface layer. Comparison of obtained resultswith previous results shows that there is no significant changes occurred in properties of the riverbed material except little changes in composition of surface layer especially in the fine material.The river under the current flow conditions with flow rate in around of 500m3/s will reserve to thesame bed material properties in the future.
This research deals with the viability of using polyester fiber (PF), crumb rubber tire (CRT) and cellulose fiber (CF) as stabilizing waste additives in producing Iraqi SMA mixtures that sustain drain down phenomenon and moisture damage sensitivity. Different ratios of these additives (0.1, 0.2, and 0.3% by weight of aggregate and filler) were mixed with 40/50 paving asphalt by means of dry process. Unmodified and modified SMA mixtures were subjected to drain down, Marshall, static indirect tensile strength, tensile stiffness modulus, static compressive strength, tensile strength ratio and index of retained strength tests. A set of regression equations between these tests were established. In addition, an optimization table based on these tests, which can be used to select the type or amount of additive for any field applications has been determined and reported. The results indicated that the inclusion of these additives in SMA mixtures could satisfy the performance requirement of high temperature and much rain zone.
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