Study on the soil-water characteristic curve including stresses of an unsaturated soil

2010 ◽  
pp. 491-494
Author(s):  
Chun-Ni Shen ◽  
Xiang-Wei Fang ◽  
Zheng-Han Chen ◽  
Zheng-Bin Zhou
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Soil Water Characteristic Curve

Soil Water Characteristic Curve and its Applications in Tunnel

2011 ◽  
Vol 261-263 ◽  
pp. 1039-1043
Author(s):  
Yu You Yang ◽  
Qin Xi Zhang ◽  
Gui He Wang ◽  
Jia Xing Yu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Land Subsidence ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Tunnel Construction ◽  
Coupling Theory ◽  
Engineering Analysis ◽  
Soil Water Characteristic Curve ◽  
The Relationship

A soil water characteristic curve (SWCC) can describe the relationship between unsaturated soil matric suction and water content. By analyzing and researching the test data of the soil water characteristic curve researchers can initially establish the SWCC equation and apply this equation to the actual engineering analysis. In another words, this article is based on the fluid-solid coupling theory of unsaturated soil used to analyze and study the problem of land subsidence caused by tunnel construction. Numerical calculations show that the coupling results agree well with the measured curve works.

Effect of the uncertainty in soil-water characteristic curve on the estimated shear strength of unsaturated soil

2020 ◽  
Vol 21 (4) ◽  
pp. 317-330 ◽  
Author(s):  
Qian Zhai ◽  
Harianto Rahardjo ◽  
Alfrendo Satyanaga ◽  
Guo-liang Dai ◽  
Yan-jun Du
Keyword(s):  
Shear Strength ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Soil Water Characteristic Curve

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.

scholarly journals Estimation of air permeability function from soil-water characteristic curve

2019 ◽  
Vol 56 (4) ◽  
pp. 505-513
Author(s):  
Qian Zhai ◽  
Harianto Rahardjo ◽  
Alfrendo Satyanaga
Keyword(s):  
Distribution Function ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Air Permeability ◽  
Size Distribution Function ◽  
Soil Water Characteristic Curve ◽  
Permeability Function

The multiphase flow (including liquid flow and air flow) in unsaturated soil is related to many engineering problems such as contaminant transport, rainwater infiltration, and soil-water evaporation. It is proven that water flow in unsaturated soil can be estimated using the concept of the pore-size distribution function. Many models have been proposed to estimate the water flow or water permeability function, kw, from the soil-water characteristic curve (SWCC). On the other hand, a limited model has been proposed to estimate the air flow or air permeability function, ka, from the SWCC. Most of the models used for the estimation of the air permeability functions are empirical, and they are dependent on the empirical parameters. In this paper, the relative air coefficient of permeability was estimated using the concept of the pore-size distribution function. In the method proposed in this paper, no empirical parameters were adopted, and the estimation results purely depended on the soil-water characteristic curve. The proposed method was verified against experimental data from published literature.

scholarly journals Prediction of soil water characteristic curve using artificial neural network: a new approach

2018 ◽  
Vol 162 ◽  
pp. 01014
Author(s):  
Abdul-Kareem Esmat Zainal ◽  
Shaimaa Hasan Fadhil
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Soil Properties ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
New Approach ◽  
Soil Water Characteristic Curve ◽  
Important Relationship ◽  
Artificial Neural

Soil-Water Characteristic Curve (SWCC) is an important relationship between matric suction and volumetric water content of soils especially when dealing with unsaturated soil problems, these problems may include seepage, bearing capacity, volume change, etc. where the matric or total suction may have a considerable effect on unsaturated soil properties. Obtaining an accurate SWCC for a soil could be cumbersome and sometimes it is time consuming and needs effort for some soils, either through laboratory tests or through field tests. Accurate prediction of this curve can give more precise expectations in design or analysis that include some unsaturated soil properties, which can save more effort and time. This work will concentrate on proposing a new approach for determining the SWCC using Artificial Neural Network (ANN) depending on some soil properties (air-entry point and residual degree of saturation) through computer software MatLab as a tool for ANN. The new approach is to plot the SWCC curve points instead of obtaining the parameters used in Brooks and Corey (BC) Model (1964), van Genuchten (VG) Model (1980), or Fredlund and Xing (FX) Model (1994). Results showed close agreement in determination of the SWCC by verification of the ANN results with an additional curve sample.

scholarly journals State of practice for use of the soil-water characteristic curve (SWCC) in geotechnical engineering

2019 ◽  
Vol 56 (8) ◽  
pp. 1059-1069 ◽  
Author(s):  
Delwyn G. Fredlund
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Characteristic Curve ◽  
Laboratory Measurement ◽  
Engineering Practice ◽  
Soil Water Characteristic Curve ◽  
Unsaturated Soil Mechanics ◽  
State Of Practice

Routine geotechnical engineering practice has witnessed a significant increase in the usage of unsaturated soil mechanics principles. Laboratory measurement of the soil-water characteristic curve (SWCC) for a soil has been labelled as a primary reason for the improved understanding of unsaturated soil behaviour. Laboratory measurement of the “shrinkage curve” has yielded further insight into the estimation of unsaturated soil property functions (USPFs). The USPFs provide the necessary information for the simultaneous numerical modeling of the saturated and unsaturated portions of the soil profile. This paper presents a state-of-practice summary of the engineering protocols that have emerged amidst the numerous research studies reported over the past couple of decades. It also introduces issues related to hysteresis associated with the SWCC and suggests a pathway forward.

Model for the prediction of shear strength with respect to soil suction

1996 ◽  
Vol 33 (3) ◽  
pp. 379-392 ◽  
Author(s):  
S K Vanapalli ◽  
D G Fredlund ◽  
D E Pufahl ◽  
A W Clifton
Keyword(s):  
Shear Strength ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Experimental Studies ◽  
Matric Suction ◽  
Glacial Till ◽  
Soil Suction ◽  
Soil Water Characteristic Curve

Experimental studies on unsaturated soils are generally costly, time-consuming, and difficult to conduct. Shear strength data from the research literature suggests that there is a nonlinear increase in strength as the soil desaturates as a result of an increase in matric suction. Since the shear strength of an unsaturated soil is strongly related to the amount of water in the voids of the soil, and therefore to matric suction, it is postulated that the shear strength of an unsaturated soil should also bear a relationship to the soil-water characteristic curve. This paper describes the relationship between the soil-water characteristic curve and the shear strength of an unsaturated soil with respect to matric suction. Am empirical, analytical model is developed to predict the shear strength in terms of soil suction. The formulation makes use of the soil-water characteristic curve and the saturated shear strength parameters. The results of the model developed for predicting the shear strength are compared with experimental results for a glacial till. The shear strength of statically compacted glacial till specimens was measured using a modified direct shear apparatus. Specimens were prepared at three different water contents and densities (i.e., corresponding to dry of optimum, and wet of optimum conditions). Various net normal stresses and matric suctions were applied to the specimens. There is a good correlation between the predicted and measured values of shear strength for the unsaturated soil. Key words: soil-water characteristic curve, shear strength, unsaturated soil, soil suction, matric suction.

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.

Use of the grain-size distribution for estimation of the soil-water characteristic curve

2002 ◽  
Vol 39 (5) ◽  
pp. 1103-1117 ◽  
Author(s):  
Murray D Fredlund ◽  
G Ward Wilson ◽  
Delwyn G Fredlund
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Soil Water ◽  
Grain Size Distribution ◽  
Unsaturated Soil ◽  
Soil Property ◽  
Characteristic Curve ◽  
Engineering Practice ◽  
Soil Water Characteristic Curve ◽  
Mass Properties

The implementation of unsaturated soil mechanics into engineering practice is dependent, to a large extent, upon an ability to estimate unsaturated soil property functions. The soil-water characteristic curve (SWCC), along with the saturated soil properties, has proven to provide a satisfactory basis for estimating the permeability function and shear strength functions for an unsaturated soil. The volume change functions have not been totally defined nor applied in geotechnical engineering. The objective of this paper is to present a procedure for estimating the SWCC from information on the grain-size distribution and the volume–mass properties of a soil. SWCCs represent a continuous water content versus soil suction relationship. The proposed method provides an approximate means of estimating the desorption curve corresponding to a soil initially slurried near the liquid limit. The effects of stress history, fabric, confining pressure, and hysteresis are not addressed. A database of published data is used to verify the proposed procedure. The database contains independent measurements of the grain-size distribution and the SWCC. The level of fit between the estimated and measured SWCCs is analyzed statistically. The proposed procedure is compared to previously proposed methods for predicting the SWCC from the grain-size distribution. The results show that the proposed procedure is somewhat superior to previous methods.Key words: soil-water characteristic curve, grain-size distribution, volume-mass properties, pedo-transfer function, unsaturated soil property functions.

Study on the Test of Soil Water Characteristic Curve

2011 ◽  
Vol 261-263 ◽  
pp. 1094-1098
Author(s):  
Yu You Yang ◽  
Qin Xi Zhang ◽  
Gui He Wang ◽  
Chen Liu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Mathematic Model ◽  
Matric Suction ◽  
Engineering Properties ◽  
Soil Water Characteristic Curve ◽  
Van Genuchten Model ◽  
The Relationship

The test of soil water characteristic curve (SWCC) and its mathematic model are present. The SWCC can describe the relationship between unsaturated soil matric suction and water content. Matric suction is an important parameter to address when studying the engineering properties of unsaturated soil. And while the measurement of substrate attraction is a very difficult issue, it is also one of the biggest obstacles in the engineering applications of unsaturated soil. By analyzing and researching the test data of SWCC researchers can initially establish the mathematic model which is the SWCC equation. The Van Genuchten model and the Fredlund and Xing model were used to simulate better the changes between the volume water content and the matric suction. Predictions were compared with experimental results to determine the simulation capability of the model for the soil of Beijing.

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