Calculation of Wave-Induced Shallow Stratum Seabed Slides in the Subaqueous Yellow River Delta

2009 ◽  
Author(s):  
Guohui Xu ◽  
Xin Wang ◽  
Congcong Wei ◽  
Zibu Fu ◽  
Qingpeng Zhao
Keyword(s):  
Slip Surface ◽  
Yellow River ◽  
Limit Equilibrium ◽  
Yellow River Delta ◽  
Friction Angle ◽  
Calculation Model ◽  
Safety Coefficient ◽  
Wave Flume ◽  
Calculation Results ◽  
Wave Induced

Wave-induced seabed slide could happen even at very gently sloping silty seabed. Based on the wave-seabed interaction, the safety coefficient calculation model of wave-induced gentle seabed slides in the seabed instability was carried out using limit equilibrium method, Bishop Method, in this paper. The calculated results shows that the effective internal cohesion c′ and the effective internal friction angle φ′ affect the location of slip surface and the magnitude of the safety coefficient significantly. The safety coefficient rises linearly with the increases of c′ and φ′ at a fixed depth. The results fit reasonable well with the slide calculation results from a wave flume experiment in laboratory. Additionally, it was concluded that the silty seabed tended to slide under wave actions at the depth less than 5 meters in the Yellow River Subaqueous Delta.

Convergence aspect of limit equilibrium methods for slopes

1990 ◽  
Vol 27 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R. N. Chowdhury ◽  
S. Zhang
Keyword(s):  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Solution Process ◽  
Iterative Solution ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Negative Slope ◽  
Slip Surfaces ◽  
Geological Discontinuity

This note is concerned with the multiplicity of solutions for the factor of safety that may be obtained on the basis of the method of slices. Discontinuities in the function for the factor of safety are discussed and the reasons for false convergence in any iterative solution process are explored, with particular reference to the well-known Bishop simplified method (circular slip surfaces) and Janbu simplified or generalized method (slip surfaces of arbitrary shape). The note emphasizes that both the solution method and the method of searching for the critical slip surface must be considered in assessing the potential for numerical difficulties and false convergence. Direct search methods for optimization (e.g., the simplex reflection method) appear to be superior to the grid search or repeated trial methods in this respect. To avoid false convergence, the initially assumed value of factor of safety F0 should be greater than β1(=−tan α1 tan [Formula: see text]) where α1 and [Formula: see text] are respectively the base inclination and internal friction angle of the first slice near the toe of a slope, the slice with the largest negative reverse inclination. A value of F0 = 1 + β1, is recommended on the basis of experience. If there is no slice with a negative slope for any of the slip surfaces generated in the automatic, search process, then any positive value of F0 will lead to true convergence for F. It is necessary to emphasize that no slip surface needs to be rejected for computational reasons except for Sarma's methods and similarly no artificial changes need to be made to the value of [Formula: see text] except for Sarma's methods. Key words: slope stability, convergence, limit equilibrium, analysis, optimization, slip surfaces, geological discontinuity, simplex reflection technique.

Wave-induced shallow slides and their features on the subaqueous Yellow River delta

2009 ◽  
Vol 46 (12) ◽  
pp. 1406-1417 ◽  
Author(s):  
Guohui Xu ◽  
Yongfu Sun ◽  
Xin Wang ◽  
Guanghai Hu ◽  
Yupeng Song
Keyword(s):  
Yellow River ◽  
Yellow River Delta ◽  
River Delta ◽  
Slope Instability ◽  
Delta Front ◽  
The Yellow River Delta ◽  
Slide Mass ◽  
Wave Induced ◽  
Water Depths ◽  
Surrounding Soil

Slope instability processes occur widely on the underwater slopes of the Yellow River delta during storms. Roughly circular depressions on the upper delta front in water depths of 4 to 8 m have been detected by acoustic surveying and their processes were observed in the laboratory. This paper analyzes the properties of geomorphic and acoustic profiles of the upper delta front and compares the engineering geologic properties of samples from the disturbed and undisturbed areas. The results indicate that the weak superficial mass could oscillate with waves and the oscillation weakened the surrounding soil under the cyclic loading. The stratum was disturbed or even destroyed with depth, the area of the slide mass enlarged gradually, and finally a collapse depression formed.

scholarly journals Calculation of Active Earth Pressure for Narrow Backfill with a Curved Slip Surface

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Zhihui Wang ◽  
Aixiang Wu ◽  
Yiming Wang
Keyword(s):  
Equilibrium Equation ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Failure Surface ◽  
Friction Angle ◽  
Force Balance ◽  
Vertical Force ◽  
The Earth

A method was proposed to calculate the earth pressure from a cohesionless backfill with a high aspect ratio (ratio of height to width of retaining wall). An exponential equation of slip surface was proposed first. The proposed nonlinear slip surface equation can be obtained once the width and height of the backfill as well as the internal friction angle of the backfill were given. The failure surface from the proposed formula agreed well with the experimental slip surface. Then, the earth pressure was calculated using a simplified equilibrium equation based on the proposed slip surface. It is assumed that the minor principal stress of the backfill near the wall and at its corresponding slip surface where the depth is the same is the same. Thus, based on the vertical force balance of the horizontal backfill strip, assuming the wall-soil interface and the slip surface is in the limit equilibrium state, defined by the Mohr–Coulomb criterion, the differential equilibrium equation was obtained and numerically solved. The calculated results agreed well with the test data from the published literature.

Research on Improvement of Merchant Shear Angle Model

2014 ◽  
Vol 894 ◽  
pp. 192-200 ◽  
Author(s):  
Shu Ting Wang ◽  
Yu Cheng Zhang ◽  
Wei Dong Gou ◽  
Chuan Jiang Liu
Keyword(s):  
Metal Cutting ◽  
Friction Angle ◽  
Calculation Model ◽  
Shear Angle ◽  
Zone Model ◽  
Analysis Model ◽  
Calculation Results ◽  
The Impact ◽  
Angle Calculation ◽  
Key Parameter

Shear angle is a key parameter to characterize the metal cutting. In this paper the Merchant analysis model of shear angle is improved. The impact of shear angle on the shear stress is quantitatively analyzed by using of the unequal division shear zone model and Johnson-Cook constitutive model, and the functional relationship between the tool-chip friction angle and the shear angle is established by Schulz empirical formula. Thus the new shear angle calculation model is established. Calculation results and experiments verify the effectiveness of the improved Merchant model.

Experimental evidence of wave-induced inhomogeneity in the strength of silty seabed sediments: Yellow River Delta, China

2013 ◽  
Vol 59 ◽  
pp. 120-128 ◽  
Author(s):  
Xiao-Lei Liu ◽  
Yong-Gang Jia ◽  
Jie-Wen Zheng ◽  
Wei Hou ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Yellow River ◽  
Yellow River Delta ◽  
River Delta ◽  
Wave Induced ◽  
Seabed Sediments

Study on Rock Mechanics in Stability State of Kangding Substation

2013 ◽  
Vol 353-356 ◽  
pp. 486-490
Author(s):  
Qian Guo ◽  
Yu Sheng Li ◽  
Lei Wang
Keyword(s):  
Slip Surface ◽  
Limit Equilibrium ◽  
Good Condition ◽  
Deformation Characteristic ◽  
Simulation Method ◽  
Front Edge ◽  
Equilibrium Calculation ◽  
Secondary Slip ◽  
Calculation Results ◽  
Finite Element Numerical Simulation

This paper uses finite element numerical simulation method to analyze the rock mass stress deformation characteristic and it illustrates that site stress state is mainly controlled by the gravitational field, while the rock basic deformation is solidification. On the foundation of blocks limit equilibrium calculation results, it shows that the global stability of the site is in good condition in a variety of extreme circumstance conditions. The blocks stability is slightly lower than sites whole stability, which is in the front edge of the site, controlled by secondary slip surface II.

Variation of Moisture Content and Safety Factor of Silt Subgrade under Rainfall Infiltration

2011 ◽  
Vol 243-249 ◽  
pp. 4161-4165 ◽  
Author(s):  
Hong Bo Zhang ◽  
Xiu Guang Song
Keyword(s):  
Moisture Content ◽  
Yellow River ◽  
Friction Angle ◽  
Rainfall Infiltration ◽  
Triaxial Tests ◽  
Saturation State ◽  
Safety Coefficient ◽  
Support Conditions ◽  
Rainfall Seepage ◽  
Capillary Phenomenon

Because of the special capillary and water-sensitive characters, the moisture content of silt subgrade in Alluvial Plain of the Yellow River is generally higher than the optimum value, which will lead to bad support conditions of subgrade. In order to analyze the water-absorbent property of silt subgrade, both the rainfall seepage and the capillary phenomenon were simulated in laboratory, which reveals that both factors have distinct effects on the moisture content of compacted silt soil. Triaxial tests of compacted silt soil reveal that the cohesive force reduces obviously with the increasing of moisture content. What’s more, the internal friction angle also reduces rapidly arriving at saturation state. By adopting Geo-slope code, the rainfall infiltration mode of silt subgrade was simulated under different rain type and rain duration. Results show that the subgrade slope is easy to lose stability because of much rainfall infiltration. In addition, the minimum safety coefficient happens at the time of rainfall ending. And the slope safety can be threatened seriously by the repetitious rainfall.

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