Triaxial Shrinkages Tests of Unsaturated Compacted Clay

2011 ◽  
Vol 194-196 ◽  
pp. 1041-1044
Author(s):  
Dong Lin Wang
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Experimental Tests ◽  
Degree Of Saturation ◽  
Mean Stress ◽  
Compacted Clay ◽  
Soil Water Characteristic Curve ◽  
Triaxial Apparatus ◽  
Soil Triaxial Apparatus ◽  
Shrinkage Coefficient

In this paper, The GDS unsaturated soil triaxial apparatus are employed for experimental tests to obtain the main characteristics of the drying paths for compacted clay. In order to study the soil water characteristic curve and shrinkage coefficient under deferent net mean stress. The results show that shrinkage index and the soil-water characteristic curve are dependent on net mean stress. At a given matric suction, with the increase of net mean stress, the void ratio and water content of soil sample is decrease, but the degree of saturation is increased.

Influences of Deviatoric Stress on the Soil-Water Characteristic Curve

2011 ◽  
Vol 243-249 ◽  
pp. 2456-2459
Author(s):  
Xiang Wei Fang ◽  
Shu Ping Jiang ◽  
Chun Ni Shen ◽  
Yun Xie ◽  
Gang Li
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Characteristic Curve ◽  
Deviatoric Stress ◽  
Mean Stress ◽  
Research Subjects ◽  
Shear Tests ◽  
Soil Water Characteristic Curve ◽  
Unsaturated Soil Mechanics

The soil-water characteristic curve (SWCC) is one of the major research subjects in unsaturated soil mechanics. To study the influence of deviatoric stress on the SWCC of an unsaturated soil, a series of triaxial drained shear tests by controlling constant net mean stress and suction were conducted. It was found that the SWCC was dependent on deviatoric stress. A unified SWCC equation was proposed including not only water content and suction, but also net mean stress and deviatoric stress.

Effect of Compaction Degree on Soil-Water Characteristic Curve of Chongming Clay

2011 ◽  
Vol 90-93 ◽  
pp. 701-706
Author(s):  
Jing Song Qian ◽  
Hang Lu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Filter Paper ◽  
Characteristic Curve ◽  
Liquid Limit ◽  
Degree Of Saturation ◽  
Paper Test ◽  
Soil Water Characteristic Curve ◽  
Gravimetric Water Content ◽  
Compaction Degree

The soil-water characteristic defines the relationship between the soil suction and gravimetric water content, w, or the volumetric water content, θ, or the degree of saturation, S. It is a convenient method to predict water content in the subgrade using the curve. But in the field tests of subgrades, the compaction degree of soil became lower with time than initially designed. With the purpose of finding out effect of compaction degree on soil-water characteristic curve, a study to the SWCC (soil-water characteristic curve) of Chongming low liquid limit clay using filter paper method was carried out and is presented in this paper. Specimens of different water contents were prepared by absorbing different amount of water, in order to better simulate the process of wetting of subgrade soil. After the filter paper test, the soil-water characteristic curve was fitted with two models, and then the effect of compaction degree on the curve was analyzed. The figures show that the compaction degree of the specimen will decrease with higher water content, and from the gravimetric water content-matric suction curve, it is found that compaction degree has an effect on air-entry value and water storage capacity.

Predicting the permeability function for unsaturated soils using the soil-water characteristic curve

1994 ◽  
Vol 31 (4) ◽  
pp. 533-546 ◽  
Author(s):  
D.G. Fredlund ◽  
Anqing Xing ◽  
Shangyan Huang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Degree Of Saturation ◽  
Residual Water ◽  
Soil Water Characteristic Curve ◽  
Coefficient Of Permeability ◽  
Permeability Function

The coefficient of permeability for an unsaturated soil is primarily determined by the pore-size distribution of the soil and can be predicted from the soil-water characteristic curve. A general equation, which describes the soil-water characteristic curve over the entire suction range (i.e., from 0 to 106 kPa), was proposed by the first two authors in another paper. This equation is used to predict the coefficient of permeability for unsaturated soils. By using this equation, an evaluation of the residual water content is no longer required in the prediction of the coefficient of permeability. The proposed permeability function is an integration form of the suction versus water content relationship. The proposed equation has been best fit with example data from the literature where both the soil-water characteristic curve and the coefficient of permeability were measured. The fit between the data and the theory was excellent. It was found that the integration can be done from zero water content to the saturated water content. Therefore, it is possible to use the normalized water content (volumetric or gravimetric) or the degree of saturation data versus suction in the prediction of the permeability function. Key words : coefficient of permeability, soil-water characteristic curve, unsaturated soil, water content, soil suction.

Experimental Study on Soil Water Characteristic Curve of Compacted Unsaturated Soil

2010 ◽  
Vol 168-170 ◽  
pp. 1285-1288
Author(s):  
Dong Lin Wang
Keyword(s):  
Soil Water ◽  
Influencing Factors ◽  
Unsaturated Soils ◽  
Stress Condition ◽  
Characteristic Curve ◽  
External Stress ◽  
Method Of Least Squares ◽  
Soil Water Characteristic Curve ◽  
Triaxial Apparatus ◽  
Soil Water Characteristic Curves

Soil water characteristic curve is one of important topics of unsaturated soils. Pressure plate extractor and GDS unsaturated triaxial apparatus are used to study influencing factors including types of soils and net mean stress. Through method of least-squares, Fredlund five-parameter model were employed to fit soil-water characteristic curves. The results show that model provided a satisfactory fit to the experimental data. Through an analysis of influencing factors, we find that not only physical condition of samples but also external stress condition can affect the shape of soil water characteristic curve.

scholarly journals Collapse behaviour of unsaturated compacted soil with different initial densities

2007 ◽  
Vol 44 (6) ◽  
pp. 673-686 ◽  
Author(s):  
De'an Sun ◽  
Daichao Sheng ◽  
Yongfu Xu
Keyword(s):  
Experimental Data ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Initial Density ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Compacted Soil ◽  
Soil Water Characteristic Curve ◽  
Volume Decrease

Very few experimental data on the mechanical behaviour of unsaturated soils exists, particularly on the collapse behaviour under general stress states, because of the technical difficulties and time-consuming nature of measuring suction and deformation. This paper presents the results of a series of controlled-suction triaxial tests on the collapse behaviour of an unsaturated compacted clay with different initial dry densities and suctions. The collapse behaviour here includes deformation characteristics, such as volume changes, and hydraulic characteristics, such as saturation changes. It is found that the wetting-caused collapse mainly depends on the mean net stress and the initial density, and that the volume decrease reaches a maximum when the specimen is under the initial yielding mean net stress. It is also found that the soil-water characteristic curve in terms of suction and degree of saturation shifts upwards with increasing specimen density. The soil-water characteristic curve of a compacted soil mainly depends upon the current density, not directly upon the stress state. In addition, experimental data show that the collapse occurs mainly in an intermediate range of suction levels, which are neither very high nor very low, and that the wetting-caused volume decrease is accompanied by an increase in the degree of saturation.Key words: unsaturated soil, density, triaxial test, suction, collapse, degree of saturation.

Nineteenth Canadian Geotechnical Colloquium: The soil-water characteristic curve: a historical perspective

1998 ◽  
Vol 35 (5) ◽  
pp. 873-894 ◽  
Author(s):  
S Lee Barbour
Keyword(s):  
Shear Strength ◽  
Conceptual Model ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Constitutive Relationship ◽  
Water Phase ◽  
Degree Of Saturation ◽  
Capillary Model ◽  
Soil Water Characteristic Curve

The constitutive relationship between water content or degree of saturation and suction is called the soil-water characteristic curve. The soil-water characteristic curve provides a conceptual framework in which the behavior of unsaturated soils can be understood. A historical review illustrates how the work of early researchers in soil science and geotechnical engineering laid the foundation for our current understanding of this relationship. Key elements of these early studies were a conceptual understanding of the soil-water characteristic curve as a relationship between the mass or volume of water stored within the soil and the energy in the water phase. It was on the basis of this conceptual model that current methods of measuring the soil-water characteristic curve were developed. Interpretative models for the distribution and geometry of the water phase in an unsaturated soil based on the capillary model have provided a useful conceptual model for understanding the effects of soil texture, gradation, void ratio, and compaction on the soil-water characteristic curve. The capillary model has also provided the foundation for recently developed techniques to predict the functional relationship between degree of saturation and shear strength, coefficient of permeability, coefficient of diffusion, and adsorption for unsaturated soils.Key words: unsaturated soils, soil-water characteristic curve, suction, shear strength, permeability, contaminant transport.

Determination and Compare Analysis for Soil Water Characteristic Curve Model in Planting Soil in Saline Region of Tianjin

2010 ◽  
Vol 12 (3) ◽  
pp. 336-341
Author(s):  
Fei CAI ◽  
Xiaohou SHAO ◽  
Zhenyu WANG ◽  
Mingyong HUANG ◽  
Yaming ZHAI ◽  
...  
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Soil Water Characteristic Curve ◽  
Curve Model ◽  
Compare Analysis

The Experiment on Soil Water Characteristic Curve Considering the Effect of Urea Concentration

2014 ◽  
Vol 919-921 ◽  
pp. 795-799
Author(s):  
Gai Qing Dai ◽  
Dong Fang Tian ◽  
Yao Ruan ◽  
Lang Tian ◽  
You Le Wang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Urea Concentration ◽  
Test Method ◽  
Materials Selection ◽  
Valuable Data ◽  
Soil Water Characteristic Curve ◽  
Concentration Test ◽  
The Impact

A new soil water characteristic curve (SWCC) experiment contemplating urea concentration is presented in the paper. We focus on the impact of the SWCC considering urea concentration test method for materials selection and introduction, experimental results, and finally, we have conducted some experiments of SWCC and obtained some valuable data which could affect urea concentration. By using linear fitting, an exponential function between water content and suction and urea concentration is established.

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