Performance of Cutoff Walls Under Hydraulic Structures Against Uplift Pressure and Piping Phenomenon

2014 ◽  
Vol 33 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Abdolreza Moharrami ◽  
Gholam Moradi ◽  
Masoud Hajialilue Bonab ◽  
Javad Katebi ◽  
Gholamreza Moharrami
Keyword(s):  
Hydraulic Structures ◽  
Uplift Pressure ◽  
Cutoff Walls

The Effect of Cutoffs on the Uplift Pressure Beneath the Hydraulic Structures Floor

2018 ◽  
Vol 6 (3) ◽  
pp. 20-28
Author(s):  
Faisal Al Tabatabaie ◽  
Dhabia Sabeeh Al Waily
Keyword(s):  
Potential Energy ◽  
Hydraulic Structure ◽  
Hydraulic Structures ◽  
Outer Face ◽  
Analogue Model ◽  
Electrical Analogue ◽  
Uplift Pressure ◽  
Different Depths ◽  
The Stability ◽  
Critical Sections

The use of cutoffs underneath the hydraulic structures is considered a safe solution to ensure the stability of hydraulic structure against uplift pressure and piping phenomenon in addition to the sliding and overturning forces of the water. These cutoffs are used at critical sections underneath the floor of hydraulic structure to substitute with their depths the horizontal lengths of the creep line of the hydraulic structure base. In this paper, the experimental method- by using electrical analogue model- was carried out to plot the flow net and study the efficiency of the front and rear faces of the cutoffs for dissipating the potential energy of the percolating water underneath the floor of hydraulic structure. An electrical analogue model which was used in this study consists of twenty five models with different depths of upstream and downstream cutoffs. After plotting the flow net for all models, it is concluded that the efficiency of the inner sides are less than that of the outer sides which were investigated before in this topic of this work that both faces reduction values in the uplift pressure are considered the same, where the efficiency of the outer face of upstream cutoff is (70.35) % and for the inner face is (29.64)%, while for the downstream cutoff the efficiency for the outer face is (76.21)% and for the inner face is (23.79)% .

scholarly journals The Effects of Grout Curtain Parameters on Uplift and Piping Phenomenon; Case Study: Sattarkhan Dam

Hydrology ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 71
Author(s):  
Kambiz Meshkabadi ◽  
Yousef Zandi
Keyword(s):  
Numerical Models ◽  
Grout Curtain ◽  
Hydraulic Structures ◽  
Uplift Pressure ◽  
The Core ◽  
Horizontal Drainage ◽  
Potential Risks ◽  
Dam Core ◽  
Water Seal

Design of earth dams and their issues during and after construction is very important for residents downstream of the dam because of the potential risks and possible breakdowns. In the design of dams, various forces influence the dam body, including uplift pressure and piping phenomenon which should be considered in order to ensure the safety of the dam. Among the measures taken to prevent the washing away phenomenon, the reduction of the output gradient, and the leakage discharge from beneath the hydraulic structures, construction of the grout curtain and installation of the drainage are applicable. Therefore, in order to investigate the effect of various parameters such as the gradient angle of the grout curtain, length, and distance and the number of grout curtains, as well as the length of the drainage on the pressure and output gradient of the numerical models, were considered in current study. For this purpose, the SEEP/W software was used for modeling on Sattarkhan Dam as a case study. The results of the analysis showed that the use of the Qa’im grout curtain at the upstream of the dam has the highest resistance against the pressure and piping phenomenon. The results also showed that increase in the length of the curtain of the water seal increases safety against uplift and piping phenomenon. The use of further spacing between the two grout curtains under the core of the dam led to increase in overall pressure or reduction in safety against uplift pressure. Increase in the length of the horizontal drainage reduced the effects of uplift pressure and output gradient. Results show that period of 70 to 110 degree is appropriate for curtain angle and setting curtain in upstream of dam core with angle of 70 to 80 degree is optimum and economic. A length of 30 m is optimum for curtain. The number of 2 curtains is also optimum. Studying various scenarios of distance of 2 curtains in dam core indicates that distance of 6 m is optimum and also length of 18 m for horizontal drainage is optimum.

scholarly journals Model test and numerical investigation of the effect of the impervious layer’s slope on seepage characteristics under hydraulic structures

Water SA ◽  
2019 ◽  
Vol 45 (1 January) ◽  
Author(s):  
Rasool Ghobadian ◽  
Hamed Shekari ◽  
Parisa Koochak
Keyword(s):  
Model Validation ◽  
Hydraulic Structure ◽  
Experimental Tests ◽  
Maximum Error ◽  
Hydraulic Structures ◽  
Seepage Discharge ◽  
Uplift Pressure ◽  
Uplift Force ◽  
Anisotropic Soil ◽  
Seepage Characteristics

Although the impervious layer under a hydraulic structure is rarely flat, the effect of the impervious layer’s slope, under the hydraulic structure, on seepage characteristics has not been studied to date. Therefore, this study investigated the effect of the downhill and uphill impervious layer’s slope (downhill/uphill foundation slopes) on the uplift pressure, seepage discharge and exit gradient under hydraulic structures. In order to reach this goal, a numerical model has been developed in which the general equation of fluid flow in non-uniform; anisotropic soil is solved by the finite volume method on a structured grid. The model validation was performed using the measured data from experimental tests. The results of the model validation indicated that the model calculates the seepage discharge and uplift pressure with a maximum error of less than 3.79% and 3.25%, respectively. The results also indicated that by increasing the downhill foundation slope (DFS) the uplift force decreases, but the exit gradient and seepage discharge increase. Moreover, by increasing the uphill foundation slope (UFS), the uplift force increases but the exit gradient and seepage discharge decrease. In addition, the results demonstrate that by increasing the length of the cut-off wall the effect of the DFS on decreasing and UFS on increasing the uplift pressure force becomes more severe. However, the effect of the DFS on increasing the seepage discharge and UFS on decreasing the seepage discharge becomes milder as the length of the cut-off wall increases. By increasing the DFS, from zero to −15%, the exit gradient increases 19.75% and 14.4% for 1 m and 6 m cut-off lengths, respectively.

scholarly journals Influence of Cavity Under Hydraulic Structures on Seepage Characteristics

2018 ◽  
Vol 7 (4.20) ◽  
pp. 461 ◽  
Author(s):  
Asmaa Abdul Jabbar Jamel ◽  
Muataz Ibrahim Ali
Keyword(s):  
Coefficient Of Determination ◽  
Hydraulic Structures ◽  
Structure Model ◽  
Sheet Pile ◽  
Uplift Pressure ◽  
Coefficient Of Permeability ◽  
Seepage Characteristics ◽  
The Stability ◽  
Seepage Properties ◽  
Different Characteristics

Cavities under hydraulic structures have a significant influence on the stability of these structures. This study depends on (SEEP/W) software for a hydraulic structure model with an upstream sheet pile. Thus, different results are obtaining for discharge, uplift pressure and exit gradient. For the output a dimensional analysis is perform to study the effect of these variables. Also (SPSS), where special equations are obtaining for seepage discharge, uplift pressure and exit gradient has a coefficient of determination and correlation (0.9, 0.89, 0.8) respectively. The effect of the presence of the cavities on seepage properties whenever the location of the cavity before the sheet pile increased its effect on the discharge and uplift pressure in contrast to the exit gradient where cavity approaching the end of the structure that is increasing its impact on the exit gradient. Also decrease the depth of the cavity from ground increase its impact on the characteristics of seepage, as well as the greater coefficient of permeability and the diameter of the cavitation will increase seepage properties. Also shows that when comparing the state of the presence of cavity with the absence of it, different behaviors with different characteristics of seepage will appear at different percentage.

METHODS OF FORECAST CALCULATION OF GROUND WATER BACKWATER IN THE ZONE OF HYDRAULIC STRUCTURES INFLUENCE

2020 ◽  
pp. 109-116
Author(s):  
N.P. KARPENKO ◽  
◽  
M.A. SHIRYAEVA
Keyword(s):  
Numerical Model ◽  
Computer Program ◽  
Ground Water ◽  
Programming Language ◽  
Hydraulic Structure ◽  
Hydraulic Structures ◽  
Software Model ◽  
Computational Program ◽  
Specific Object ◽  
Zone Of Influence

The purpose of the work is to consider methods for calculating the forecast of groundwater backwater in the zone of influence of hydraulic structures. The analysis of analytical dependences of calculation of the forecast of groundwater backwater for various calculation schemes is carried out. For a homogeneous scheme of the geofiltration structure, a numerical model is proposed and a computational program for calculating the groundwater backwater is developed. It allows calculating the groundwater backwater from the channel at any time in the discrete mode. To simplify the solution of the problem of calculating the groundwater backwater, a computer program was created in the programming language Phyton Version 8.3 which quickly solves this hydrogeological problem. A possible range of geofiltration parameters is proposed for calculating the groundwater backwater near main channels. The adaptation and implementation of the software model was carried out for a specific object – the Bolshoy Stavropol channel-5, for which forecast calculations were made. The results of predictive calculations of groundwater backwater are the basis for the assessment of areas of possible flooding – the territory within which the level of ground water increases as a result of their backup by a hydraulic structure.

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