scholarly journals Exploring the Occurrence of Clogging in Highly Permeable Coarse Soils of Dam Foundations

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Jianquan Ma ◽  
Hao Peng ◽  
Shibo Li ◽  
Zhao Duan ◽  
Xinshe Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Dominant Effect ◽  
Infiltration Process ◽  
Foundation Soil ◽  
Dam Foundation ◽  
Effective Aperture ◽  
Pore Blockage ◽  
Soil Media ◽  
Dam Foundations ◽  
Coarse Soil

Leakage through the permeable coarse soils of dam foundations in Tibet, China, lessened over time without any additional antiseepage measures. In fact, clogging generated during the infiltration process is recognized as the major factor in reducing leakage. A laboratory study was conducted to understand clogging in highly permeable coarse soil of a dam foundation with the primary aim of determining the clogging patterns and optimum clogging particle size (PS). Seven replicate experiments were constructed using soil media with PS ranges of 32–64 mm, 16–32 mm, 8–16 mm, 4–8 mm, 2–4 mm, 1-2 mm, and 0.5–1 mm to observe clogging after feeding the soil media with sediments of different PSs. The experimental results showed that four clogging patterns were formed in different PSs of the coarse foundation soil. The ratio of the effective aperture of the soil Dea and the equivalent clogging particle size dede/Dea had a dominant effect on the four clogging patterns (surface clogging, de/Dea>1; surface-internal clogging, 0.5<de/Dea≤1; internal partial pore blockage, 0.25<de/Dea≤0.5; and unclogging, de/Dea≤0.25). The assessment criterion of the optimum clogging pattern was determined by 0.5<de/Dea≤1, and from that, the optimum clogging PS do was calculated.

Dominant effect of particle size on the CeO2 preferential evaporation during plasma spraying of La2Ce2O7

2017 ◽  
Vol 37 (4) ◽  
pp. 1577-1585 ◽  
Author(s):  
Li-Shuang Wang ◽  
Shan-Lin Zhang ◽  
Tao Liu ◽  
Chang-Jiu Li ◽  
Cheng-Xin Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Plasma Spraying ◽  
Dominant Effect ◽  
Effect Of Particle Size ◽  
Preferential Evaporation

scholarly journals Dynamic Stability Discrimination Method for Concrete Dam under Complex Geological Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Liaojun Zhang ◽  
Tianxiao Ma ◽  
Hanyun Zhang ◽  
Dongsheng Chen
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Dynamic Instability ◽  
Limit Equilibrium ◽  
Element Model ◽  
Safety Factors ◽  
Stability Calculation ◽  
Dam Foundation ◽  
Geological Conditions ◽  
Dam Foundations

The instability of dams will bring immeasurable personal and property losses to the downstream, so it has always been a trendy topic worthy of investigation. Currently, the rigid body limit equilibrium method is the most commonly used method for the dynamic stability analysis of dams. However, under the action of earthquakes, the instability of the integral dam-foundation system threatens the safety of the dams and is of great concern. In this paper, a stability analysis method that can reflect the complex geological structural forms of dam foundations is proposed in this paper. The advantages are that this method deals with the difficulty in assuming sliding surfaces and the lack of quantitative criteria for the dynamic instability analysis of dams with complex geological structural forms of dam foundations. In addition, through the method, the sliding channels that may appear in the dam foundations can be automatically searched under random earthquake action, and the safety factors of the dynamic instability of dams be quantitatively obtained. Taking a high RCC gravity dam under construction in China as an example, the proposed method is applied to the three-dimensional finite element model of the dam-foundation system of this dam, and then the dynamic stability calculation is carried out. Through this method, the formation process of the dam foundation’s plastic zone and the failure of sliding channels with different strength reduction coefficients are studied on and analyzed detailedly, and the quantitative acquisition of the safety factors is realized. The results show that the method is reasonable and feasible, and helps provide a new idea and method for the dynamic stability analysis of dams.

scholarly journals A sample formation procedure to obtain homogeneous post-erosion particle size distribution

2019 ◽  
Vol 92 ◽  
pp. 02015
Author(s):  
Shijin Li ◽  
Adrian R. Russell
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Internal Erosion ◽  
Triaxial Tests ◽  
Experimental Investigations ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
The Matrix ◽  
Homogeneous Particle ◽  
Coarse Soil

Internal erosion (suffusion) is caused by water seeping through the matrix of coarse soil and progressively transporting out fine particles. The mechanical strength of soils within water retaining structures may be affected after internal erosion occurs. However, most experimental investigations on the mechanical consequences of internal erosion have used triaxial tests on samples having nonhomogeneous particle size distributions along their lengths. Such nonhomogeneities arise from the most commonly used sample formation procedure, in which seeping water enters one end of a sample and washes fine particles out the other. In this paper a new soil sample formation procedure is presented which results in homogeneous particle size distributions along the direction of seepage, that is at all locations along a sample's length.

Calculation and Control of Seepage of Hardfill Dam with Different Foundation

2011 ◽  
Vol 255-260 ◽  
pp. 3666-3670
Author(s):  
Yun Feng Peng
Keyword(s):  
Drainage System ◽  
Dam Construction ◽  
Seepage Discharge ◽  
Seepage Field ◽  
Dam Foundation ◽  
Uplift Pressure ◽  
Calculation Results ◽  
And Control ◽  
Dam Foundations ◽  
Geologic Condition

As a new dam type, Hardfill dam has been arisen recently. The suitable geologic condition of t Hardfill dam construction was analyzed based on considering its characteristics in this paper; it was also studied how to choose the reasonable impervious and drainage system to control the dam body and foundation’s seepage on a given geologic condition to make sure the safety of the project. On the basis of analyzing the foundation geologic conditions of many common dam types, two kinds of typical Hardfill dam foundation were put forward. The seepage field law of dam foundation was analyzed by dam foundation seepage discharge, uplift pressure and seepage gradient of some typical positions after setting reasonable impervious and drainage measures on the two kinds of dam foundations. It is indicated by the calculation results that the adaptability of Hardfill dam foundation is comparatively nice, and the safety of dam foundation can be ensured if appropriate impervious and drainage measures are adopted.

Exploring the clogging process in coarse soil deposits in a dam foundation

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Jianquan Ma ◽  
Xiaojie Zhao ◽  
Shibo Li ◽  
Hao Peng ◽  
Lele Xiao ◽  
...  
Keyword(s):  
Dam Foundation ◽  
Soil Deposits ◽  
Coarse Soil

scholarly journals Effect of African Catfish Mucilage Concentration on Stability of Nanoemulsion Using D-Optimal Mixture Design

2021 ◽  
Vol 11 (15) ◽  
pp. 6672
Author(s):  
Adebanji Olasupo Oluwole ◽  
Daniel Imwansi Ikhu-Omoregbe ◽  
Victoria Adaora Jideani ◽  
Seteno Karabo Ntwampe
Keyword(s):  
Particle Size ◽  
Structural Stability ◽  
Goodness Of Fit ◽  
Mixture Design ◽  
African Catfish ◽  
Dominant Effect ◽  
Lack Of Fit ◽  
Oil In Water ◽  
Alternative Means ◽  
Functional Components

Nanoemulsions are alternative means of incorporating functional components into systems. This research aims to model the effect of African catfish mucilage (ACM) concentrations on the particle size (PS) of stable oil-in-water (O/W) nanoemulsions formulated by ultrasonication. A D-optimal mixture design was used to study the influence of three mixture components (MCs) ACM, oil, and water on PS. Morphology and PS were determined with Cryo-TEM and Zetasizer. Findings show that the higher the ACM–emulsifier oil ratio, the higher the nanoemulsion stability as depicted by lower PS. ACM concentration was the factor that had the most dominant effect on the dependent variable (DV) PS. Morphology studies revealed that structural stability was a result of ACM which encapsulated the nanoemulsion by mucoadhesion. The model’s lack of fit (F [0.17, 0.11] = 0.3104; p = 1.49) was not significant, and the predicted R-squared value was 0.9977 and adequate precision was 104.158 indicating a model with adequate goodness-of-fit. The model was adequate to determine the effects of the three MCs on the precise stability parameter for the investigated dependent variable particle size. Therefore, ACM could be used as a natural stabilizer in oil-in-water nanoemulsions that are applicable in biomedical and personal care industries.

scholarly journals DYNAMIC CALCULATION OF THE PLANE ELASTIC "DAM-FOUNDATION" SYSTEM

2021 ◽  
Vol 4 (5) ◽  
pp. 16-23
Author(s):  
K. Salyamova
Keyword(s):  
Strain State ◽  
Mathematical Formulation ◽  
Earth Dam ◽  
Shear Stresses ◽  
Earth Dams ◽  
Safe Operation ◽  
Stress Strain ◽  
Foundation Soil ◽  
Dam Foundation ◽  
Stress Strain State

design, construction, and reliable and safe operation of earth dams (more than 60 of them are in operation in the Republic of Uzbekistan located in seismic region) put forward requirements for the continuous improvement of the calculation methods for loads; as required by regulatory methods for fundamental (static) and special (dynamic) load combinations. These regulatory methods do not take into account the nonhomogeneous nature of the behavior and piecewise heterogeneity of the characteristics of foundation, and the stress-strain state (SSS) of an earth dam under constant or temporary loads, which is necessary for reliable and safe operation, especially in seismic regions. A general mathematical formulation of problems for earth dams in a plane elastic formulation is given. Dynamic calculations were conducted to determine the stress-strain state of an earth dam, taking into account the design features and real piecewise-nonhomogeneous physical and mechanical characteristics of soil of the structure body and base (these characteristics were provided by the design organization). The problem was solved by the numerical finite element method. The eigenfrequencies and modes of vibrations of the plane "structure-foundation" system are determined, considering the homogeneous and piecewise-nonhomogeneous characteristics of the foundation soil; the corresponding analysis of the behavior of the system was made. The stress-strain state of the “dam-foundation” system was investigated using calculated frequencies. The calculation results were lines of equal displacements (horizontal, vertical), normal and shear stresses in the “dam-foundation” system.

Results and implications of seismic performance studies for Duncan Dam

1994 ◽  
Vol 31 (6) ◽  
pp. 979-988 ◽  
Author(s):  
P.M. Byrne ◽  
A.S. Imrie ◽  
N.R. Morgenstern
Keyword(s):  
Seismic Performance ◽  
Soil Parameters ◽  
Confining Stress ◽  
Foundation Soil ◽  
Dam Foundation ◽  
Indirect Approach ◽  
Empirical Correction ◽  
Undisturbed Samples ◽  
Flow Slides ◽  
Design Earthquake

Screening-level studies indicated large zones of the foundation soil beneath Duncan Dam could be triggered to liquefy under the design earthquake, resulting in flow slides that could lead to breaching of the dam. In these studies, estimates of the key soil parameters were obtained from an indirect procedure using penetration tests and Seed's chart, which is based on field experience during past earthquakes together with empirical correction factors for high confining stress and static bias. This is state-of-the-practice procedure in North America and is used because of the difficulty in retrieving and testing undisturbed samples of sand. With the high confining stresses present at the site, the indirect approach gave very low values of the key liquefaction properties of the soil, and the use of such low values in analyses indicated that major and costly remedial measures were required. Thus a more direct approach was undertaken. This involved both direct and semidirect determination of the key soil parameters through an extensive laboratory study based on testing of undisturbed samples obtained by freezing in situ. The results showed that both the triggering resistance and the residual strength values of the soil were very much higher than those obtained from the indirect approach. Analyses carried out using direct measurement of the key soil parameters indicated that the dam, in fact, would be stable. Key words : embankment dam, foundation liquefaction, sand, seismic performance, triggering resistance, undisturbed sample.

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