مروة عبدالله ميري شلاش

Abstract: The spillway capacity can be Adjusted to increase the crest of spillway length, or increasing the coefficient discharge or effective head, or any others permutation of these approaches. In a standing spillway, a labyrinth weir constructing is a case of an active technique for increasing the length of spillway crest and as resultant increase the capacity of discharge (up to 3-4 times) for the identical effective head. Therefore, labyrinth weirs are well-matched to the sites. There are many effective factors such as width to the height of the weir which is called a vertical aspect ratio (w/p); head of water to height of crest ratio (Ht/p), angle of the side wall (α), and conditions of channel that effect on the weir capacity and labyrinth weir hydraulic design of. In this paper four different geometric variations applied to a two cycle of sharp crested trapezoidal labyrinth weir under free flow condition which include changing of vertical aspect ratio (w/P) (width to height ratio) that have effects on the hydraulic efficiency of the labyrinth weir and state the effect of the hydraulic parameter Ht/P on the coefficient of discharge ( ) over weir. It was concluded that decreasing w/P has affirmative effect on the discharge capacity. On adverse it has influence of decreasing the discharge coefficient by about 20% (when increasing w/P to 1.5), while increasing it to 2.0 and 2.5 will cause more reduction to ranging from 32% to 25% for w/P=2.0 & 40% to 35 for w/P=2.5. The smaller values of the head Ht provide more discharge coefficient Keywords: Labyrinth weirs, vertical aspect ratio, crest coefficient and hydraulics.

Rockfill gabions considered one of important self-spillway hydraulic structures, used as water distributor, regulator and other purposes. An experimental investigation was carried out to note the effect of the change of longitudinal slope and the change of rockfill size on the velocity at downstream side of gabion, all tests carried out under through flow regime type, the monosized of rockfill were used (-76,+64)mm, (-64,+50)mm, and (-50,+37.5)mm, with three longitudinal slope 0,0.014, and 0.028. Wooden frame meshed-side gabion with constant dimensions, 220 cm length of the bottom side 150 cm length of upper side of gabion, 0.3m width, and 0.35 m height. The result showed that the effective of discharge increasing on the value of velocity of downstream by increasing of rockfill size for same longitudinal slope, and the effect of discharge decreasing on the velocity at downstream by increasing the longitudinal slope for the same rockfill size, a dimensional analysis concept used and non-linear regression by using IBM SPSS 21 program, to develop an empirical formula to estimate the velocity at downstream.

This study was initiated to better understand the sediment transport capacity of a reach on Euphrates river at downstream of Al-Abbasia City bridge’s in a length of 6 km approximately which is have a combined characteristic of straight and meander morphology. A one of arithmetical model for representing flow and calculating transportation of sediment capacity of the elaborated reach was carried out and run by utilizing the HECRAS (4.1.0) program and making use of measuring of field for carrying out and running standardization processes. Flow velocity and sediment transport capacity were estimated for a range of discharge from 40 to 100 m3/sec. Locations of the low flow velocity were specified. The comparison between sediment potential rating curves of these locations showed that the sediment transport potential of the reach cross sections at distance from 1000 to 1200, 2200 to 3000 and 3580 m from the end of the reach, is less than that of the other cross sections of this reach were under 50 tones/day. Also observes that for the straight parts on the studied reach the discharge increasing gives less sediment transport capacity while the meandering parts of the reach were in reverse behavior.

Water resources and hydraulic engineering projects have been upward rapidly in all over the world, accordingly the prediction of roughness coefficient is essential criteria to design open channels, and related hydraulic structures. The aims of this research are to find out the effect of changing beds materials and discharge on coefficient of roughness (n), the beds that used in the tests are smooth which represented by original channel bed (steel plate), rough bed material which is a gravel bed and waved bed .The experimental work was performed in a rectangular flume with dimension of ( 15 m* 0.3 m* 0.45 m) long, wide and deep, respectively with different value of slope (1:200 and 1:500) to analyze slope effect on coefficient of roughness in addition to the effect of channel bed material. The experimental work showed that The coefficient of roughness reduced when the discharge increases for specified slope and channel bed, The slope of the channel and bed roughness is the main factors affected on determining coefficient of roughness and when the channel slope increases the coefficient of roughness increases, the coefficient of roughness is decreased when using smooth bed and it is increased when channel bed is waved. The percentage change in the Manning coefficient due to changing in slope and channel bed is (112.6%) when slope equal to (1/200) and the channel bed changed from smooth to rough , (184%) when the bed changed from rough to waved, and (33.6%) when channel bed changed from rough to waved. And for (1/500) slope, the percentage change in the Manning coefficient equal to (33.5%) when the bed changed from smooth to rough, (80%) when changed from smooth to waved, and (33.1%) when changed from rough to waved.

Abstract This paper present nonlinear finite element analysis to predict the load deflection behavior of circular cell cofferdam under lateral load by using ANSYS (ANalysis SYStem) (version 12.1) computer program, eight-node solid element (SOLID 45) has been used to model filling soil and the same element by using overlap and glue technique to model steel sheet pile of cofferdam. The bond between steel sheet pile and filling soil has been modeled by using nodes merge. The full Newton-Raphson method is used for the nonlinear solution algorithm. Single circular cell of width to height ratio (0.75, 1.00) have been analyzed and their results are compared with experimental data including the following factors: the effect of berm ratios (back fill of cell) (0.4H), embedment depth ratios (0.2H, 0.4H), Wet subbase soil was used as filling material. The results obtained using the finite element models represented by the load applied at one third of the cell cofferdam height deflection curves show good agreement (small difference) with the experimental data for the case that considered in this study. The difference between the numerical ultimate loads and the corresponding experimental ultimate loads is in the range between (0-5.56)%. Only in the case of circular cell cofferdam on ground with b/H=1 the difference was 25%. For numerical analysis at used berm ratio of (0.4H) has increase the cell resistance (50%).while in experimental study the increase in cell resistance was (33%).

Abstract This paper presents nonlinear finite element analysis to predict the load deflection behavior of circular cell cofferdam under lateral load by using ANSYS (ANalysis SYStem) (version 12.1) computer program, eight-node solid element (SOLID 65) has been used to model the concrete cofferdam and (line search on) method is used for the nonlinear solution algorithm. In this study circular concrete cofferdam on concrete foundation and another case circular concrete cofferdam on concrete foundation with (0.4 from the cell height) concrete berm the (width to height ratio (D/H) = 1.0). Also in this work the fractured cracking or crushing types of fracture occurred at concrete elements are indicated as circles located at sampling points inside the elements, each integration point of a brick element can crack in up to three different planes. The first crack occurred at an integration point is shown with a red circle outline, the second crack is presented with a green circle outline, and the third crack is shown with a blue circle outline. The cracks were occurred around the place of applied load and the crushed which represented by octahedron outline occurred at the place of applied load and from numerical analysis found that using (0.4H) concrete berm reduce the displacement by about (34.22%) .