ليث جواد عزيز الجراح

In this study, laboratory experiments were performed to evaluate the effects of the weir geometry of a Piano Key Weir (PKW) type B on the discharge coefficient under free flow conditions. Experiments were conducted in a 15m long, 0.3m wide and 0.45m deep rectangular glass-walled flume. The experimental work includes testing of fourteen PKW models which results 290 tests to cover the effects of weir length and height, up-and downstream key widths, upstream apex overhangs length, dam height and noses length on the weir flow discharge coefficient as well PKW with outlet stepped key were considered in the analysis. Considering the experimental data, the dimensional analysis allowed the development of relations between discharge coefficient and the shape of the PKW and gave a good agreement. Experimental results showed that the most influential parameters for the tested PKW models are the Relative length L/W, Key widths W ⁄W , PKW Height B/P, and Overhangs length B ⁄B. The effectiveness of Piano Key Weir at low heads ratio (H/P = 0.25) is up to 400% relative to Creager weir at the same head.

This study presents an experimental investigation to evaluate the effect of notch at sidewall of a Piano Key Weir (PKW) of type B and C on the discharge coefficient under free flow conditions. Model tests were conducted in a 15m long, 0.3m wide and 0.45m deep rectangular glass-walled flume. Eight physical models were prepared for both types: two traditional PKW type-B and C, and six notched models designed in similar dimensions to the traditional one. It was concluded that using staged PKW does not have a major effect on discharge capacity, water depth above the upstream apex (h1) for type B is greater than type C relative to its upstream piezometric head.

he research presents an experimental study of the interaction between cavity and adjacent hydraulic structure in sandy soil. Experimental studies were performed to investigate the effects of the different factors (such as cavity locations and size of the cavity) on the quantity of the seepage, steady time and flow line . Different sizes and locations of the cavity are investigated in flow media. It was found the diameter of the cavity is an important parameter. Dimensional analysis techniques and (STATISTICA) program were used for finding new formula with based on the experimental data, which are used to compute the quantity of seepage. This formula was derived to predict the quantity of the seepage in terms of spacing between the sheet pile wall and center of the cavity in upstream and downstream zones, spacing between water level and center of the cavity in upstream and downstream zones.

Bearing capacity of soil is an important factor in designing circular footing. It is directly related to foundation dimensions and consequently its performance. The calculations for obtaining the bearing capacity of a soil needs many varying parameters, for example soil type, depth of foundation, unit weight of soil, etc. In this work, the comparison between the values of bearing capacity of circular footing on gypseous soil before and after improvement determined by two different methods, the first method using compacted cement dust (Case1). The improvement were performed by making trench under the footing filled with compacted cement dust (at its optimum moisture content) at three depths [(Depth of trench, D =Width of trench, B =2 * the radius of footing R); (D=2B=4R) ; (D=3B=6R)], the trench had the same footing Dimensions, The second method is reinforcing gypseous soil with biaxial geogrids (Case2) have been shown to be an effective method for improving the ultimate bearing capacity of granular soils.

This study is focuses with the possibility of using Tanser SS2 geogrid as a reinforcement material to increase the bearing capacity and reduce settlement under strip foundation located on sandy soil with cylindrical cavity. Forty five laboratory model tests were conducted using a steel box with 1250 mm in length, 800 mm in depth and 250 mm in width. Increment loads were applied on strip footing with 100 mm in width and 250 mm in length. Since the length of the model foundation was approximately the same as the width of the test box and length of the cavity, it can be assumed that an approximate plane strain condition exist during the tests. For each model, the relationship between the applied pressure and the corresponding settlement was detected. From the results of a series of laboratory tests, it was found that the bearing capacity ratio (BCR) of the soil increases with increasing in width of geogrid, (b/d) specially when the cavity center coincides with the centerline of the strip footing (X/d=0). The effect of geogrid width will reduce with moving the cavity away from the strip footing. When the width of the geogrid layer was high (b/d), the maximum increase in bearing capacity ratio can be noticed at high depth of geogrid layer (h/d=3), and this bearing capacity ratio becomes very low at small geogrid width for same value of (h/d=3). At zero lateral distance ratio (X/d) and two layer reinforced, the higher generated bearing capacity are noted when the vertical distance between two layer geogrid is (S/d=1, i.e optimum value), but at (S/d=0.5), the values of footing resistance are lowest. The effects of number of layer (N) on the bearing capacity of strip footing are very small at low value of geogrid width. At geogrid width (b/d >1), the case of geogrid (N=3, i.e optimum value) record the highest values of the bearing capacity ratio. The location of peak strain readings of the geogrid surface is depends upon the cavity position. As the geogrid layers were near to the base of the footing, the values of reinforcement strains were increased.

Three dimensional Computational Fluid Dynamic (CFD) model are intend to investigate the flow patterns around groins under different conditions. Used k- turbulent model and VOF method to predict the complex flow around groins .The initial part of this study con-cerns to the experimental investigations of flow patterns. The results from the measurements in terms of water elevation, velocity magnitudes according to groins are showed. These were used to validate the Computational Fluid Dynamic model. The results of CFD models showed good agreements with the corresponding experimental measurements. Many aspects were conducted on the CFD model for most important design parameters, such as, Contraction ratio (Lg/B), and Orientations. Results showed that, the Reattachment length is about 12-13 times the impermeable Groins length; Groins with (Lg/B) more than 20% will increased the velocity and shear stress by 76, and 99 % respectively, Groins oriented either normal to the flow or slightly downstream for best performance. Groins oriented on downstream reduces scour (shear stress) at the end of the groins by 50%.