Journal of Hydraulic Structures
Volume:9 Issue: 2, Summer 2023

Bridges are the most important river structures that are destroyed due to erosion. The change in the shape of the river geometry along the course of the river leads to erosion of the river bed and can also affect scour around the pier. Therefore, in this paper, the effect of the convergence and divergence ratio of 15% in the 180º bend was investigated on the amount of scour around the pier of the circular bridge using the SSIIM numerical model. The results showed that the SSIIM software has a high ability and accuracy in determining the scour pattern in bend channels. The most scour depth appeared in the bend with 15% convergence and it increased by 1.75 and 2.33 times compared to the uniform and divergent bend, respectively. Also, the most sedimentation height occurred in the bend with 15% convergence and it increased by 3.25 and 4.33 times compared to the uniform and divergent bend, respectively.

This research numerically investigates the structure behavior of steel jacket platform stand on 20 degrees inclined seabed and exposed to the earthquake. Considering the inclined seabed, the effect of the main variables on the structural behavior of the steel jacket platform subjected to the four famous earthquakes are discussed. The most effective variables of the structural response contain stresses and displacement. The stresses and displacement of the main four legs and as well as at the top of jacket structure will be as indicator for the structural response. ABAQUS 6.14 is used to model and analyze. The research finds that the change in the mass location will generate torsion effects which vary according to the leg's location and its length. In the sloping seabed it is necessary to use a stiffer tubular section to resist the torsional effect.

Sluice gates are utilized in dams and irrigation channels as regulating structures in the channel have the role of regulating the water level for proper water intake of upstream intakes. As high velocity and energy of the flow issuing from these hydraulic structures scour occurred in erodible downstream beds. Occurrence of the hydraulic jump is very possible, and when it forms, therefore the necessity of investigating the flow condition increases. The scouring phenomenon is a time evolution and a long-time procedure. This research focused on time effects on experimental data received by a sediment bed profiler at different times from the experimental setup conducted in a laboratory. The maximum scour depth (dse), the maximum dune height (hd), the horizontal distance of the maximum scour depth from the beginning of the sedimentary bed (xse), and the horizontal distance of the maximum dune height from the beginning of the sedimentary bed (xd) were investigated. Laboratory observations show that the extension of the location of the maximum scour depth and the maximum height of the dune formed with time is evident. The laboratory data for the dimensionless conditions of 4 scour profiles characteristics including dse/b0, hd/b0, xse/b0, and xd/b0 were analyzed by the nonlinear regression method, and separate equations were proposed for each characteristic. RMSE=0.045, 0.0677, 0.358, and 2.146 respectively, and the R2 =0.996, 0.975, 0.974, and 0.977 respectively.

This paper aims to investigate the effects of uncertainty in soil characteristics and dam geometry on seepage flow using the hybrid Multivariate Adaptive Regression Splines (MARS) and Monte Carlo Method (MCM). A computer program based on Darcy flow is developed in the Fortran language to calculate the discharge flow. After validating the numerical FORTRAN code with experimental outputs, firstly, the Deterministic Finite Element Method (DFEM) was used to obtain Seepage Exit Discharge (SED) in Steady State Condition (SSC), and MCM was used for probabilistic analysis to account for uncertainty in random parameters. The program monitored Pore Water Pressure (PWP) changes and integrated them into the time/space domains. To ensure minimal error, the results of the models were compared by Standard Error Calculation (SEC). The research also introduced a new component to compare the seepage flow resulting from the analysis of models in a dimensionless manner called the Effective Discharge MARSplines (EDM). In the present research, the combination of Machine Learning (ML) and MCM algorithms was used in an innovative way for Random Finite Element Method (RFEM) calculations. The results of the research indicate that a 17.9% increase in the Hd/Hu ratio in the deterministic analysis results in a 29.3% decrease in EDM, while in the probabilistic analysis, a similar increase leads to a 19.02% decrease in EDM. Upon comparing deterministic and stochastic models, it can be concluded that deterministic analysis is more accurate and exhibits less error when compared to the probabilistic model.

In this study, the effect of different hydraulic parameters on the energy loss of flow over gabion stepped spillways are examined using physical models and comparisons are made with the other studies. Two end sills including rectangular and inclined shapes are used on each spillway step. The results showed that the influence of end sills in gabion stepped spillways with lower slopes is greater than that of spillways with higher slopes. The influence of end sills on energy loss in spillways with d50=40 mm and S = 1:2 is about 10% more than the spillways with d50=10 mm and S = 1:1 (d50 is the mean diameter of gravel in the gabion and S is the downstream slope of the gabion stepped spillways, vertical: horizontal). Energy dissipation in spillways with d50=10 mm and S = 1:2 is about 30 to 35 percent more than spillways with d50=10 mm and S = 1:1. Hence, end sills in spillways with gravel size of d50 = 10 mm have the most significant impact on the energy loss. Instead, the influence of the rectangular end sill on the energy loss is about 3-4% more than the effect of a triangular (inclined) end sill.

One of the most popular tools for dealing with the seepage problem in embankment dams is using different types and shapes of downstream drains. So, the paper presents a comprehensive study of the different drainage systems through such dams. Many earth dam models are investigated through the SEEP/W model representing different dimensions and geometry of downstream drains. A comparison is carried out between the present study and previous experimental and numerical studies and the results of the present study are almost close to the previous studies. The present work concludes that the most influential factor in a horizontal drain is the length, and the thickness has a negligible effect. The reasonable length ratio of a horizontal drain (L/B) is about 0.34 according to the minimum seepage. The angle of toe drains has a slight effect on the different seepage parameters. The performance of the inclined chimney drain is better than the vertical drain to control the seepage.