scholarly journals Assessment of the Upstream Slope Stability of Darbandikhan Rockfill Dam during Drawdown

2021 ◽  
Vol 9 (1) ◽  
pp. 8-15
Author(s):  
Sirwan Gh. Salim ◽  
Krikar M. G. Noori
Keyword(s):  
Steady State ◽  
Numerical Analysis ◽  
Slope Stability ◽  
Water Level ◽  
Factor Of Safety ◽  
Computer Software ◽  
Loading Conditions ◽  
Upstream Slope ◽  
Rockfill Dam ◽  
The Stability

Earth and rockfill dams face a variety of loading conditions during lifetime. One of the most critical loading conditions is the rapid drawdown of water level after steady state conditions. Rapid drawdown may cause instability of upstream slope of the dam. The present work examines the stability of a rockfill dam under different drawdown rates in terms of factor of safety for the upstream slope of the dam. For this purpose, a computer software named GeoStudio 2012 SEEP/W and SLOPE/W has been used for the numerical analysis. The results showed that the drawdown rate has a significant effect on stability of rockfill dam in which increasing the drawdown rate from 1 m/day to 10 m/day decreases the stability of the dam by 33%. Based on the outcomes, for the studied case the drawdown rate (1 m/day) can be recommended.

scholarly journals The dam slope stability under the transient condition during an extreme flood

2021 ◽  
Vol 280 ◽  
pp. 10010
Author(s):  
Svitlana Velychko ◽  
Olena Dupliak
Keyword(s):  
Slope Stability ◽  
Water Level ◽  
Flood Control ◽  
Transient Condition ◽  
Mountainous Area ◽  
The Core ◽  
Upstream Slope ◽  
Flood Level ◽  
Extreme Flood ◽  
The Stability

Mountain Flood Control Reservoir (MFC Reservoir) is used to reduce the flood level in the mountainous area and protect settlements downstream. The special feature of this MFC Reservoir is the fast filling during 1-2 days, short storage time at the maximum level and speed falling of the water level. Simulation of the MFC Reservoir operation was carried out on the software Midas GTS NX. Two rockfill dam models were developed: with the core and with the screen. The fluctuation of the water level in the MFC Reservoir was taken as the transformed flood from 1% to 10% probability. The fast water level change in the MCF Reservoir creates the transient seepage condition during the flood. During the water level rising in the MFC Reservoir, the upstream slope stability gradually increases because of hydrostatic pressure. After the water level begins to fall with rate of 0.7 m/hour, the slope stability decreases. The core or screen location significantly affects the stability of the upstream dam slope. The simulation showed that the upstream slope of the dam with the core was more stable. Due to the high hydraulic conductivity, the upstream dam prism with the berm significantly dampens the pore pressure in the dam and increases the stability of the upstream slope.

Some difficulties associated with the limit equilibrium method of slices

1983 ◽  
Vol 20 (4) ◽  
pp. 661-672 ◽  
Author(s):  
R. K. H. Ching ◽  
D. G. Fredlund
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stability Limit ◽  
Limit Equilibrium Method ◽  
Soil Conditions ◽  
Side Force ◽  
Limit Equilibrium Methods ◽  
Equilibrium Method ◽  
The Stability

Several commonly encountered problems associated with the limit equilibrium methods of slices are discussed. These problems are primarily related to the assumptions used to render the inherently indeterminate analysis determinate. When these problems occur in the stability computations, unreasonable solutions are often obtained. It appears that problems occur mainly in situations where the assumption to render the analysis determinate seriously departs from realistic soil conditions. These problems should not, in general, discourage the use of the method of slices. Example problems are presented to illustrate these difficulties and suggestions are proposed to resolve these problems. Keywords: slope stability, limit equilibrium, method of slices, factor of safety, side force function.

Numerical analysis of the anti-seepage measures for high earth rockfill dam on deep overburden

2012 ◽  
Vol 170-173 ◽  
pp. 1872-1877 ◽  
Author(s):  
Jun Yan ◽  
Si Hong Liu ◽  
Bin Zhou
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Seepage Field ◽  
Seepage Analysis ◽  
The Real ◽  
Rockfill Dam ◽  
The Stability ◽  
High Rockfill Dam ◽  
At Home

The anti-seepage measures of a high earth rockfill dam built on the foundation with a deep overburden affects the stability and safety of the dam greatly. Nowadays there are few researches on this area both at home and abroad. On the basis of the finite element seepage analysis of the Pubugou high rockfill dam in which core walls and two cut-off walls are designed as the anti-seepage measures, the real seepage behavior of the seepage field is obtained in this paper, as well as the seepage characters of the seepage field under different arrangements of the cut-off walls. The conclusions have a certain referential value for the design of the anti-seepage measures for the similar projects with the foundation of a deep overburden.

scholarly journals Unsteady Seepage Behavior of an Earthfill Dam During Drought-Flood Cycles

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 17 ◽  
Author(s):  
Ziyang Li ◽  
Wei Ye ◽  
Miroslav Marence ◽  
Jeremy Bricker
Keyword(s):  
Pressure Gradient ◽  
Water Level ◽  
Pore Pressure ◽  
Internal Erosion ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Upstream Slope ◽  
Earthfill Dams ◽  
The Stability ◽  
Pore Pressure Gradient

Climate change with extreme hydrological conditions, such as drought and flood, bring new challenges to seepage behavior and the stability of earthfill dams. Taking a drought-stricken earthfill dam of China as an example, the influence of drought-flood cycles on dam seepage behavior is analyzed. This paper includes a clay sample laboratory experiment and an unsteady finite element method seepage simulation of the mentioned dam. Results show that severe drought causes cracks on the surface of the clay soil sample. Long-term drought causes deeper cracks and induces a sharp increase of suction pressure, indicating that the cracks would become channels for rain infiltration into the dam during subsequent rainfall, increasing the potential for internal erosion and decreasing dam stability. Measures to prevent infiltration on the dam slope surface are investigated, for the prevention of deep crack formation during long lasting droughts. Unsteady seepage indicators including instantaneous phreatic lines, equipotential lines and pore pressure gradient in the dam, are calculated and analyzed under two assumed conditions with different reservoir water level fluctuations. Results show that when the water level changes rapidly, the phreatic line is curved and constantly changing. As water level rises, equipotential lines shift upstream, and the pore pressure gradient in the dam’s main body is larger than that of steady seepage. Furthermore, the faster the water level rises, the larger the pore pressure gradient is. This may cause internal erosion. Furthermore, the case of a cracked upstream slope is modelled via an equivalent permeability coefficient, which shows that the pore pressure gradient in the zone beneath the cracks increases by 5.9% at the maximum water level; this could exacerbate internal erosion. In addition, results are in agreement with prior literature that rapid drawdown of the reservoir water level is detrimental to the stability of the upstream slope based on embankment slope stability as calculated by the Simplified Bishop Method. It is concluded that fluctuations of reservoir water level should be strictly controlled during drought-flood cycles; both the drawdown rate and the fill rate must be regulated to avoid the internal erosion of earthfill dams.

scholarly journals Slope Stability of an Earth Dam during Drawdown Conditions (KHASA-CHAI Dam) as a Case Study

2018 ◽  
Vol 7 (4.37) ◽  
pp. 17
Author(s):  
Adnan Jayed Zedan ◽  
Mariwan Ridha Faris ◽  
Ahmed Amer Abdulsattar
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Earth Dam ◽  
Downstream Face ◽  
Upstream Slope ◽  
Maximum Water Level ◽  
Water Drawdown ◽  
Action Taking ◽  
Safe Condition

Aiming in this research was to have a clear view about the behavior of Khasa-Chai Dam during the draw down action taking into consideration the newly built of this dam which was filling during the time of this article, the upstream slope was investigated by taking drawdown of the water from the reservoir. This dam is consists of the zoned embankment with a total length of (2.36 km) with an upstream slope (1v:3h) and downstream slope (1v:2h). Slope stability was investigated during the drawdown of the water from the reservoir by considering the water in the reservoir to be at maximum water level and by taking two cases during the rapid and slow drawdown. SLOPE/W which is a sub program from Geo-Slope software was used in association with SEEP/W software to find the factor of safety of the upstream slip surface during the drawdown conditions. It was noticed from the drawdown conditions that the phreatic line falls almost at the same position for both cases. Also for both cases the factor of safety of the upstream slip surface falls above the value of (1.0) and that is mean the upstream slope is in a safe condition when the water drawdown. The exit gradient and the rate of flow at the downstream face decrease with time as the water in the reservoir drawdown which means the factor of safety against boiling increases with time.  

scholarly journals A Dual-Aggressive Model of Tumor-Immune System Interactions

2019 ◽  
Vol 15 (10) ◽  
pp. 155
Author(s):  
Abdulkareem Ibrahim Afolabi ◽  
Normah Maan
Keyword(s):  
Steady State ◽  
Immune System ◽  
Numerical Analysis ◽  
Mathematical Models ◽  
Malignant Tumor ◽  
Physical Phenomenon ◽  
Biomedical Literature ◽  
The Stability ◽  
Total Elimination ◽  
Insight Into

<p class="0abstract">Biomedical literature suggested that the tumor-immune system physical phenomenon usually climaxes into either tumor elimination or escape. In retort to the phenomenological mechanics of tumor-immune system interaction, researchers had used Mathematical models mostly prey-predator and competitive extensively, to model the dynamics of tumor immune system interaction. However, these models had not accounted for total elimination and, or escape of tumor as hypothesizes by immunoediting hypotheses. In this work, we propose a dual aggressive model based on the biological narration of tumor-immune system interactions. The stability analyses of tumor-negative steady state are stable if the rate at which body cells dies is less than their proliferation rate a confirmation of biological listed causes of the tumor. The tumor-positive steady state is always unstable and saddle with the likelihood of either elimination or escape of tumor. Numerical analysis validates our analytical results and provides insight into the dynamics of the benignant and malignant tumor. The immunosuppression by tumor is not only visible but also validated by both analytical and numerical analysis.</p>

Comparing slope stability analysis using limit equilibrium and finite elements simulations of deep-seated landslides along the western margin of the Main Ethiopian Rift

2021 ◽  
Author(s):  
Tesfay Kiros Mebrahtu ◽  
Thomas Heinze ◽  
Stefan Wohnlich
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Limit Equilibrium Method ◽  
Strength Reduction ◽  
Ethiopian Rift ◽  
Seismic Load ◽  
Main Ethiopian Rift ◽  
Western Margin ◽  
The Stability

&lt;p&gt;Landslides and ground failures are among the common&amp;#160;geo-environmental hazards in many of the tectonically active hilly and mountainous terrains of Ethiopia, such as in the western margin of the Main Ethiopian Rift in Debre Sina area. Besides the geological preconditioning, bi-modal monsoon and seismic events in the tectonically highly active region are usually suspected triggers. In order to minimize the damage caused by the slope failure events, a detailed investigation of landslide-prone areas using numerical modelling plays a crucial role. The aim of this study is to assess the stability of slopes, to understand the relevant failure mechanisms, and to evaluate and compare safety factors calculated by the different available numerical methods. The stability was assessed for slopes of complex geometry and heterogeneous material using the limit equilibrium method and the shear strength reduction method based on finite elements. Furthermore, numerical analysis was done under static and pseudo-static loading using the horizontal seismic coefficient to model their stability during a seismic event. The slope stability analysis indicates that the studied slopes are unstable, and any small scale disturbance will further reduce the factor of safety and probably causing failure. The critical strength reduction factors from the finite element method are significantly lower than the factor of safety from the limit equilibrium method in all studied scenarios, such as Bishop, Janbu Simplified, Spencer and Morgenstern-Price. The difference is especially evident for heterogeneous slopes with joints, which often are initiation points for the failure planes. The simulations show that slope stability of landslide prone hills in the study area strongly depends on the saturation conditions and the seismic load. The studied slopes are initially close to failure and increased pore-pressure or seismic load are very likely triggers.&lt;/p&gt;

scholarly journals Stability Assessment and Optimization Design of Lakeside Open-Pit Slope considering Fluid-Solid Coupling Effect

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Wenchen Fan ◽  
Ping Cao ◽  
Ke Zhang ◽  
Kaihui Li ◽  
Chong Chen
Keyword(s):  
Slope Stability ◽  
Water Level ◽  
Lake Water ◽  
Optimization Design ◽  
Great Influence ◽  
Water Levels ◽  
Open Pit ◽  
Stability Of Slopes ◽  
The Stability ◽  
Slope Design

Chengmenshan copper mine, located at Jiujiang city in the Jiangxi Province, is a rarely lakeside open-pit mine in China. Since the open-pit is very close to Sai Lake, the seasonally changed water level and the distance between lake and slope have great influence to the stability of open-pit slope. Based on the drill data and geological sections, a numerical model of the slope is built. With the fluid-mechanical interaction associated, the stability of the slopes is numerically analyzed, in which different lake water levels and lake-slope distances are taken into consideration. The comparative analysis shows that a larger lake-slope distance can promise better slope stability and weaken the sensitivity of slope stability to water. The stability of slopes with different heights is analyzed to find that the stability weakens and the sensitivity is enhanced with the height increasing. To the most serious situation, the slope height and the lake water level being 238 m and 17.2 m, respectively, theFsvalue equals 1.18945 which is extremely closed to the allowable safety factor of 1.20 for slope design. According to the minimumFsfor slope design, the minimum distance between lake and open-pit slope is found to be 60 m.

scholarly journals Slope Stability Analysis of Kattery Watershed in Nilgiris District

2019 ◽  
Vol 12 (6) ◽  
pp. 163-169
Author(s):  
C. Rajakumar ◽  
P. Kodanda Rama Rao
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Internal Friction ◽  
Slope Stability ◽  
Factor Of Safety ◽  
Slope Stability Analysis ◽  
Strength Parameter ◽  
Angle Of Internal Friction ◽  
Shear Strength Parameter ◽  
The Stability

The slope stability analysis is always under severe threats in many parts of nilgiris district, causing disruption, loss of human life and economy. The stability of slopes depends on the soil shear strength parameters such as Cohesion, Angle of internal friction, Unit weight of soil and Slope geometry. The stability of a slope is measured by its factor of safety using geometric and shear strength parameter based on infinite slopes. In this research, investigation was carried out at 5 locations in Kattery watershed in nilgiris district. The factor of safety of the slope determined by Mohr Coulomb theory based on shear strength parameter calculated from direct shear test which is a conventional procedure for this study. Artificial. Neural Network (ANN) Model is used to predict the factor of safety. The input parameters for the (ANN) are chosen as Cohesion, Angle of internal friction, Density and Slope angle and the factor of safety as output. The results obtained in ANN method were compared with that of conventional method and observed a good agreement between these two methods.

scholarly journals SLOPE STABILITY ASSESSMENT OF THE UPSTREAM SLOPE OF THE DRY MOUNTAIN FLOOD CONTROL RESERVOIR DURING THE FLOOD

2021 ◽  
pp. 4-12
Author(s):  
Svitlana Velychko ◽  
Olena Dupliak ◽  
Tetiana Kurbanova
Keyword(s):  
Slope Stability ◽  
Water Level ◽  
Flood Control ◽  
Limit Equilibrium ◽  
High Water ◽  
Limit Equilibrium Method ◽  
Water Levels ◽  
The Body ◽  
Stability Assessment ◽  
Upstream Slope

The flood control is one of the priority goal for successful economic activity on the areas that are periodically suffer from floods. Such areas are the mountainous regions of the Ukrainian Carpathian Mountains. Floods on the mountain rivers are repeated several times each year, and are characterized by the sudden water level rise with almost the same rapid decrease of the water level. Active flood protection measures include dry mountain flood control reservoirs, the principle of which is to transform part of the flood runoff and to accumulate water for the short time in the the artificial reservoir, with followed rapid emptying to the minimum level. The complex hydraulic regime is formed in the body of the dam which forms the flood control reservoir during the flood, that is different from the operation of the water permanent reservoir. The design of the flood control structures is car-ried out in accordance with Ukrainian building codes for the construction of the water reservoirs with constant water level, and require testing the stability of the downstream slope for the maximum water levels under steady state seepage conditions and assessment the upstream slope stability during the water level decreasing  from the maximum level calculated in the steady state condition, these calculations do not correspond to the real seepage processes in the body of the dam of the dry flood control reservoir. Therefore, the purpose of this work is to determine the necessary boundary conditions of the flood control reservoir operation and upstream slope stability assessment by the limit equilibrium method. In the article the operation of the dry mountain flood control reservoir was analysed and found that the dam was characterized by two states: dry reservoir with water minimum water level and variable position of the seepage curve in the core and the upstream prism during the flood. The main factors influencing the upstream slope stability are the physical and mechanical properties of the soil, the laying of the slope, the period of time when the high-water level is maintained and the intensity of water level dropping. The upstream slope stability was evaluated by the Morgenstern & Price and Ordinary methods on the Slope/w software package. After the first 25 hours of the flood (period of high-water levels and the next water level dropping) the Safety Factor evaluated by limit equilibrium methods began to decrease, and reached the minimum value during the greatest seepage curve gradients at the time between 45 and 50 hours. Slope stability calculations by the limit equilibrium method were compared with the results of calculations performed by the SRM method, the values ​​of the Safety Factor and the way of their change during the flood evaluated by Ordinary and SRM methods almost coincide, which indicates the reliability of the results obtained by different methods of slope stability analysis

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