scholarly journals Research on Interlayer Bonding Quality Control Method of Dam Concrete Based on Equivalent Age

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5192
Author(s):  
Wei-Jia Liu ◽  
You-Bo Wang ◽  
Qing-Bin Li ◽  
Xiao-Feng Gao ◽  
Yao-Shen Tan ◽  
...  
Keyword(s):  
Relative Permeability ◽  
Early Warning ◽  
Permeability Coefficient ◽  
Flux Ratio ◽  
Bonding Quality ◽  
Strength Coefficient ◽  
Equivalent Age ◽  
Dam Concrete ◽  
Electric Flux ◽  
Interlayer Bonding

Interlayer bonding quality is the key to the stability and durability of dam concrete. In this study, interlayer splitting tensile strength, relative permeability coefficient, and electric flux of dam concrete at different temperatures were tested. The relationships between equivalent age and strength coefficient, relative permeability coefficient ratio, and electric flux ratio were established. Meanwhile, a comprehensive early-warning and control system of dam interlayer bonding quality based on the above relationships was proposed. The results showed that the interlayer mechanical properties, impermeability, and anti-chloride ion permeability of dam concrete decreased with the increase of temperature. Moreover, the equivalent age was linearly correlated with strength coefficient, relative permeability coefficient ratio, and electric flux ratio of concrete. The correlation coefficients were 0.986, 0.973, and 0.924, respectively. In addition, the interlayer bonding quality of dam concrete can be effectively controlled by the early-warning system established according to the relationship between equivalent age and interlayer properties parameters.

A UNIFIED FRACTAL MODEL FOR PERMEABILITY COEFFICIENT OF UNSATURATED SOIL

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940012 ◽  
Author(s):  
GAOLIANG TAO ◽  
XIAOKANG WU ◽  
HENGLIN XIAO ◽  
QINGSHENG CHEN ◽  
JIANCHAO CAI
Keyword(s):  
Relative Permeability ◽  
Unsaturated Soil ◽  
Permeability Coefficient ◽  
Unsaturated Soils ◽  
Fractal Theory ◽  
Characteristic Curve ◽  
Fractal Model ◽  
Computational Effort ◽  
Model Parameters ◽  
Mechanical Coupling

Due to the significant challenges in the measurements, evaluation of permeability coefficient for unsaturated soil is of immense importance for investigating the seepage and hydro-mechanical coupling problems of unsaturated soil. However, the predictions of existing typical models reveal significance divergence for permeability coefficient of unsaturated soils even under identical conditions. In particular, the existing models are greatly restricted in their practical application due to their complexity in the form of integral expressions that require significant computational effort. Here, a simplified unified model is presented to estimate the relative permeability coefficient. First, a fractal-form of soil–water characteristic curve (SWCC) is derived from fractal theory. Then, on the basis of the proposed SWCC models, the classical models (i.e. Childs and Collis-George (CCG) model, Burdine model, Mualem model and Tao and Kong model, respectively) for evaluating the permeability coefficient of unsaturated soil are converted to be presented in fractal forms. It is interestingly found that the fractal forms of these models are enormously similar. Based on these observations, a simplified unified fractal model for the relative permeability coefficient of unsaturated soil is proposed, where only two parameters (i.e. fractal dimension and air-entry value) are included, thereby significantly reducing the computational efforts. The detailed procedure for determining model parameters is elaborated. The accuracy of this model is verified by comparing its predictions with the experimental data for over 12 types of unsaturated soils. The results highlight that, compared with existing models, the proposed model would be much more efficiently used for estimating the relative permeability coefficient of unsaturated soils, thereby facilitating its application for investigating the associated seepage and hydro-mechanical coupling problems in practice.

The Research on the Effect of Granite Powder on Concrete Performance

2012 ◽  
Vol 204-208 ◽  
pp. 3760-3764 ◽  
Author(s):  
Pi Jie Ying ◽  
Fu Sheng Liu ◽  
Shu Xia Ren ◽  
Gang Gang Dong
Keyword(s):  
Mechanical Property ◽  
Compressive Strength ◽  
Relative Permeability ◽  
Experimental Research ◽  
Permeability Coefficient ◽  
Cement Based Materials ◽  
Result Show ◽  
Granite Powder

Abstract: The experimental research on the effect of different incorporation of granite powders on the workability, mechanical property and impermeability performance of concrete is carried out. The result show that the concrete with an appropriate dosage of granite powder exhibits favorable workability, impermeability performance and cohesiveness. And granite powders agree with cement-based materials. Within some dosage of granite powders, the compressive strength of the mixture is approximate to that of common concrete. When the 10% of cement was replaced by the granite powder, good impermeability performance exhibits, with the relative permeability coefficient 30% lower than that of common concrete.

scholarly journals Simple Graphical Prediction of Relative Permeability of Unsaturated Soils under Deformations

2021 ◽  
Vol 5 (4) ◽  
pp. 153
Author(s):  
Gaoliang Tao ◽  
Qing Wang ◽  
Qingsheng Chen ◽  
Sanjay Nimbalkar ◽  
Yinjie Peng ◽  
...  
Keyword(s):  
Relative Permeability ◽  
Unsaturated Soil ◽  
Permeability Coefficient ◽  
Unsaturated Soils ◽  
Sandy Loam ◽  
Characteristic Curve ◽  
Prediction Method ◽  
Unified Model ◽  
Application Range ◽  
Before And After

At present, there are only a few existing models that can be used to predict the relative permeability of unsaturated soil under deformations, and the calculation process is relatively complex. In order to fit the measured value of the relative permeability coefficient of unsaturated soil before deformation, this work employs the simplified unified model of the relative permeability coefficient of unsaturated soil, and it obtains the index λ before deformation of the soil. In addition, the value of index λ remains unchanged before and after deformation. Based on the actual measured value of the soil–water characteristic curve before deformation, the air-entry value prediction model is used to predict the air-entry value of soil with different initial void ratios. The relative permeability coefficient of unsaturated soil is then conveniently predicted using the graphical method in combination with the simplified unified model. The method is validated by using the test data of silt loam, sandy loam, and unconsoildated sand. The results show that the predicted results are consistent with the measured values. The prediction method in this paper is simple and overcomes the limitations associated with the determination of the index λ. It expands the application range of the unsaturated relative permeability coefficient model while improving the accuracy of predictions.

Early Warning Models for Bank Failures: Lessons from the Late 2000s Great Recession

2012 ◽  
Author(s):  
Xiaofei Li ◽  
Cesar L. Escalante ◽  
James E. Epperson ◽  
Lewell F. Gunter
Keyword(s):  
Early Warning ◽  
Great Recession ◽  
Bank Failures

The CARE Telematics Network for the Surveillance of Influenza in Europe

1995 ◽  
Vol 34 (05) ◽  
pp. 518-522 ◽  
Author(s):  
M. Bensadon ◽  
A. Strauss ◽  
R. Snacken
Keyword(s):  
Public Health ◽  
Early Warning ◽  
Early Warning Systems ◽  
Warning Systems ◽  
Surveillance Networks ◽  
Spanish Flu ◽  
The 1950S ◽  
National Networks ◽  
First Time

Abstract:Since the 1950s, national networks for the surveillance of influenza have been progressively implemented in several countries. New epidemiological arguments have triggered changes in order to increase the sensitivity of existent early warning systems and to strengthen the communications between European networks. The WHO project CARE Telematics, which collects clinical and virological data of nine national networks and sends useful information to public health administrations, is presented. From the results of the 1993-94 season, the benefits of the system are discussed. Though other telematics networks in this field already exist, it is the first time that virological data, absolutely essential for characterizing the type of an outbreak, are timely available by other countries. This argument will be decisive in case of occurrence of a new strain of virus (shift), such as the Spanish flu in 1918. Priorities are now to include other existing European surveillance networks.

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