scholarly journals Calculation Method of Fastening the Upper Slope of the Land Bund for Erosion and Strength

2021 ◽  
Vol 7 (6) ◽  
Author(s):  
E. Hasanov ◽  
A. Mammadov ◽  
H. Aliyev
Keyword(s):  
Water Level ◽  
Wind Waves ◽  
Dead Volume ◽  
Maximum Speed ◽  
Engineering Measures ◽  
Combined Action ◽  
The Stability ◽  
Ice Water ◽  
Natural Slopes ◽  
Upper Slope

To protect the slopes of the ground dam from the devastating effects of wind waves, ice, water flow, precipitation and other factors, a number of engineering measures are provided. Based on this, an engineering decision is taken on the choice of materials for fastening structures, as well as methods for calculating their stability. When calculating the stability of the upper slope, two cases of a combination of loads and impacts are mainly considered. One of them is the reduction of the water level in the reservoir with maximum speed, and the other is the case when the water level in the reservoir is at the lowest operational level. The article investigates the processes of sliding of natural slopes of the upstream dam. Taking into account the combined action of the forces of filtering, weighing and vapor pressure, as well as the force of hydrostatic pressure to the level of dead volume. The equation for the stability coefficient of a circular-cylindrical slip of a uniform natural slope of the upstream dam has been obtained.

scholarly journals Effect of Strength Anisotropy on the Stability of Natural Slopes

2021 ◽  
Vol 710 (1) ◽  
pp. 012025
Author(s):  
Magnus T Aamodt ◽  
Gustav Grimstad ◽  
Steinar Nordal
Keyword(s):  
Strength Anisotropy ◽  
The Stability ◽  
Natural Slopes

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 Modelling the Impacts of Bathymetric Changes on Water Level in China’s Largest Freshwater Lake

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1469 ◽  
Author(s):  
Lingyan Qi ◽  
Jiacong Huang ◽  
Junfeng Gao ◽  
Zhen Cui
Keyword(s):  
Water Level ◽  
Water Resource Management ◽  
Freshwater Lake ◽  
Lake Ecosystem ◽  
Spatial Gradient ◽  
Dramatic Decline ◽  
Hydrodynamic Processes ◽  
Lake Poyang ◽  
The Stability ◽  
Bathymetric Changes

A recent dramatic decline in water level during the dry season in China’s largest freshwater lake (Lake Poyang) significantly influenced water availability and biogeochemical processes. To learn the potential causes of water level decline, this study investigated the hydrodynamic response to bathymetric changes during three typical hydrological years by scenario simulation using Environmental Fluid Dynamics Code (EFDC). The simulation results indicated that bathymetric changes resulted in a water level decrease during a low water level period. Inter-annual variation in the decrease rate implied that water level in typical dry and wet years were influenced more significantly than that in moderate hydrological years. A spatial gradient in the distribution of water level changes was also observed, which was mainly concentrated in the main channel. Water velocities also slowed down, weakly corresponding to the decrease in water level during the low water level period. Overall, bathymetric changes caused by sand mining contributed to water level and velocity variations, influencing the stability and sustainability of the lake ecosystem. This study can potentially enhance our understanding of the hydrodynamic processes in Lake Poyang and support water resource management.

Interpretation of the limits in shear strength in binary granular mixtures

2001 ◽  
Vol 38 (5) ◽  
pp. 1097-1104 ◽  
Author(s):  
Luis E Vallejo
Keyword(s):  
Shear Strength ◽  
Laboratory Tests ◽  
Relative Concentration ◽  
Frictional Resistance ◽  
Glass Beads ◽  
Rock Fragments ◽  
Structural Support ◽  
Granular Mixtures ◽  
The Stability ◽  
Natural Slopes

Many natural slopes and rockfill structures are made of a mixture of rock fragments and sand-size particles. To analyze the stability of such natural slopes and rockfills, a knowledge of how rock–sand mixtures develop their shear strength is needed. Laboratory tests conducted on mixtures of glass beads of two different sizes (5 and 0.4 mm) have indicated that their shear strength depends upon the relative concentration by weight of the large and small beads in the mixtures. If the concentration by weight of the large beads is greater than 70%, the shear strength of the mixtures is controlled by the frictional resistance of the large beads. If the concentration of the large beads is less than 40%, the shear strength of the mixtures is controlled by the frictional resistance of the small beads. If the concentration of the large beads is between 40 and 70%, the shear strength of the mixture is partially controlled by the frictional resistance provided by the large beads in the mixtures. These limits are very similar to those reported for rock–sand mixtures. To date, no explanation has been put forward to account for why these limits exist. This study presents an explanation for their existence. The explanation is based on the porosity developed by the mixtures and the type of structural support provided by the coarse and fine grains.Key words: shear strength, granular mixtures, porosity, fabric, compaction.

The Characteristics of Seepage Field and Numerical Analysis on the Stability of Reservoir Landslide

2012 ◽  
Vol 594-597 ◽  
pp. 2512-2519 ◽  
Author(s):  
Xiao Song Tang ◽  
Ying Ren Zheng ◽  
Yong Fu Wang
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Underground Water ◽  
Strength Reduction ◽  
Seepage Field ◽  
Coupling Analysis ◽  
Reservoir Landslide ◽  
Water Level Changes ◽  
Quantitative Basis ◽  
The Stability

The stability of reservoir landslide would be influenced obviously by the fluctuation of water level, especially when the water descends, which is different from common landslide. Due to the unsteady seepage of underground water inside slope caused by the change of water level, the stability analysis of reservoir landslide through fluid-solid coupling is very complicated. At present, most people hold the view qualitatively that the less the permeability coefficient is and the faster the water level changes, the more unfavorable it is to the stability. This view lacks quantitative basis. Based on FEM strength reduction, the paper analyzes the influence of different sets of descending speed and permeability coefficient on the stability of reservoir landslide through fluid-solid coupling analysis. The paper also conducts the relevant analysis on the change of the characteristics of seepage field inside the slope, which provides basis for the study of the failure mechanism and the forecast of reservoir landslide.

The Stability of Natural Slopes: Discussion

1945 ◽  
Vol 105 (5/6) ◽  
pp. 192
Author(s):  
Leonard Brooks ◽  
S. E. Hollingworth ◽  
W. D. Evans ◽  
Reginald Bee ◽  
H. L. Richardson ◽  
...  
Keyword(s):  
The Stability ◽  
Natural Slopes

scholarly journals Stability Analysis of Hydrodynamic Pressure Landslides with Different Permeability Coefficients Affected by Reservoir Water Level Fluctuations and Rainstorms

Water ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 450 ◽  
Author(s):  
Faming Huang ◽  
Xiaoyan Luo ◽  
Weiping Liu
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Hydrodynamic Pressure ◽  
Water Level Fluctuations ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Coefficient ◽  
Permeability Coefficients ◽  
Landslide Stability ◽  
The Stability

It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients are simulated based on saturated-unsaturated seepage theory and finite element analysis. The operating conditions of stability coefficients calculation are reservoir water level variations between 175 m and 145 m, different rates of reservoir water level fluctuations, and a three-day continuous rainstorm. Results show that the stability coefficient of the hydrodynamic pressure landslide decreases with the drawdown of the reservoir water level, and a rapid drawdown rate leads to a small stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. Additionally, the landslide stability coefficient increases as the reservoir water level increases, and a rapid increase in the water level leads to a high stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. The landslide stability coefficient initially decreases and then increases as the reservoir water level declines when the permeability coefficient is greater than 4.64 × 10−5 m/s. Moreover, for structures with the same landslide, the landslide stability coefficient is most sensitive to the change in the rate of reservoir water level drawdown when the permeability coefficient increases from 1.16 × 10−6 m/s to 1.16 × 10−4 m/s. Additionally, the rate of decrease in the stability coefficient increases as the permeability coefficient increases. Finally, the three-day rainstorm leads to a significant reduction in landslide stability, and the rate of decrease in the stability coefficient initially increases and then decreases as the permeability coefficient increases.

scholarly journals Evidence of creep in steep natural slopes of Champlain Sea clay

1977 ◽  
Vol 14 (4) ◽  
pp. 620-627 ◽  
Author(s):  
W. J. Eden
Keyword(s):  
Groundwater Table ◽  
Bridge Superstructure ◽  
The Stability ◽  
Clay Slopes ◽  
Natural Slopes

Three types of evidence of deep seated creep of steep natural slopes are considered: surface manifestations such as fissures and depressions; inclinometer measurements on three slopes in the Ottawa area; and movements of a bridge superstructure spanning a steep sided ravine.Results of measurements show that the movements are not continuous but occur in response to seasonal high levels of the groundwater table. The implications of the movements are discussed in relation to the stability of clay slopes.

A Regional Study of Landsliding Near Ottawa

1971 ◽  
Vol 8 (2) ◽  
pp. 315-335 ◽  
Author(s):  
D. A. Sangrey ◽  
M. J. Paul
Keyword(s):  
Soil Characteristics ◽  
Aerial Photographs ◽  
Test Results ◽  
Regional Study ◽  
Field Situation ◽  
Flow Slides ◽  
The Stability ◽  
Clay Layers ◽  
Strength Relationship ◽  
Natural Slopes

The stability of natural slopes near Ottawa has been examined from a regional approach. With the aid of aerial photographs, the density and distribution of past landslides have been ascertained, and the development of more recent slides has been traced. This information, combined with details of the present day topography, groundwater conditions, and soil characteristics, leads to a conclusion that factors influencing slope stability vary markedly throughout the region, and certain areas are much more prone to sliding than others.The strength of soils in the region is discussed, including the development of a logical shear strength relationship which incorporates the effects both of cementation strength and fissuring. The influence of sample size on the extrapolation of laboratory triaxial test results to the field situation is introduced. Details of the method of landslide analysis used are given.Considerable evidence is presented to support the presence of separate marine and freshwater clay layers in the Ottawa area, and to suggest that flow slides are confined to the upper freshwater deposit. These two clay soils are most graphically distinguished by differences in fissure spacing and pore water chemistry.

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