Experimental investigations of the soil-water characteristics of a volcanic soil

2000 ◽  
Vol 37 (6) ◽  
pp. 1252-1264 ◽  
Author(s):  
Charles WW Ng ◽  
Y W Pang
Keyword(s):  
Stress State ◽  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Hysteresis Loops ◽  
Initial Water Content ◽  
Volcanic Soil ◽  
Initial Water ◽  
Pressure Plate ◽  
Water Characteristics

Rain-induced landslides are common around the world. To analyse transient seepage and to predict pore-water pressure distribution in unsaturated slopes subjected to rainfall infiltration, it is essential to study soil-water characteristics and water permeability functions. The soil-water characteristic curve (SWCC) is a relationship between suction and water content or degree of saturation. Conventionally, only the drying soil-water characteristic curve of soil specimens is determined in a pressure-plate extractor without the application of any external stress. In this paper, the influences of initial dry density and initial water content, history of drying and wetting, soil structure, and the stress state upon the desorption and adsorption soil-water characteristics of a completely decomposed volcanic soil in Hong Kong are examined and discussed. The experimental results presented are obtained by using a conventional volumetric pressure-plate extractor and a newly modified one-dimensional stress-controllable pressure-plate extractor with deformation measurements. The SWCC of a recompacted specimen is very different from that of a natural specimen with the same initial soil density and initial water content. The SWCC of the recompacted specimen is highly dependent on the history of drying and wetting. The rates of desorption and adsorption are substantially higher at the first drying and wetting cycle than at the second drying and wetting cycle. The size of the hysteresis loop of the recompacted specimen is considerably larger than that of the natural specimens. The SWCC of soil is stress-state dependent. For recompacted specimens subjected to different stress states, the higher the applied stresses, the lower the rate of desorption and the smaller the size of the hysteresis loops. However, for natural specimens, the size of the hysteresis loops seems to be independent of the stress state. Under a higher applied stress, natural specimens exhibit lower rates of desorption and adsorption.Key words: volcanic soil, SWCC, drying and wetting, stress-state dependent.

scholarly journals Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone

2019 ◽  
Vol 1 (3) ◽  
pp. 230-240
Author(s):  
Ling Zeng ◽  
Fan Li ◽  
Jie Liu ◽  
Qianfeng Gao ◽  
Hanbing Bian
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Initial Water Content ◽  
Test Results ◽  
Initial Water ◽  
Soil Water Characteristic Curves ◽  
Water Holding ◽  
Gravimetric Water Content ◽  
Plate Apparatus

Abstract The soil-water characteristic curve (SWCC) is often used to estimate unsaturated soil properties (e.g. strength, permeability, volume change, solute and thermal diffusivity). The SWCC of soil samples is significantly affected by cyclic wetting-drying. To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone (DCM), SWCC tests were implemented using a pressure-plate apparatus. In addition, SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed. The test results showed that the volumetric water content (θ) of the DCM first decreased rapidly and then became stable as matric suction (s) increased. The initial water content affected the SWCC by altering the pore structure of the DCM. For a given number of wetting-drying cycles, the higher the initial water content, the higher the stabilized θ. At a given s value, θ decreased as the number of wetting-drying cycles increased, which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM. The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying, and was effective at describing and predicting the SWCC model for DCM.

Study on the Tests of Soil-Water Characteristic Curves of Unsaturated Soil

2013 ◽  
Vol 353-356 ◽  
pp. 16-19
Author(s):  
Xian Chun Zheng ◽  
Fang Zhao ◽  
Si Zhong Sun
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Characteristic Curve ◽  
Initial Water Content ◽  
Initial Water ◽  
Soil Water Characteristic Curve ◽  
The Matrix ◽  
Practical Engineering ◽  
Matrix Suction

Soil-water characteristic curve is used to describe the matrix suction and water content of the curve of the relationship between volume, according to the soil-water characteristic curve can be deduced the unsaturated soil shear strength, permeability coefficient, etc., this paper gives the different initial water content and different types of soil, soil-water characteristic curve for practical engineering foundation reinforcement to provide reference.

scholarly journals SWCC of Calcareous Silty Sand Under Different Fines Contents and dry Densities

2021 ◽  
Vol 9 ◽  
Author(s):  
Jian-Hua Shen ◽  
Ming-Jian Hu ◽  
Xing Wang ◽  
Chen-Yang Zhang ◽  
Dong-Sheng Xu
Keyword(s):  
Soil Water ◽  
Calcareous Soil ◽  
Characteristic Curve ◽  
Silty Sand ◽  
Dry Density ◽  
Pressure Plate ◽  
Geological Disasters ◽  
Water Characteristics ◽  
Water Holding ◽  
Plate Apparatus

Investigating the soil-water characteristics of calcareous soil has a great significance for preventing geological disasters on island-reefs as well as maintaining the foundation stability of hydraulic-filled island-reefs. In this study, calcareous silty sands with different fines contents and dry densities were studied to reveal their effects on the soil-water characteristics of calcareous soil on hydraulic-filled island-reefs. The soil-water characteristic curve (SWCC) of the calcareous silty sand was measured using a pressure plate apparatus. Taking into account the porous meso-structure, the effects of fines content and dry density on the SWCC of calcareous silty sand were analyzed, and the applicability of existing SWCC models to calcareous silty sand was verified. A SWCC model suitable for assessing soil-water characteristic of calcareous silty sand was proposed. Results of this study provide some reference for quantifying the water-holding capacity of calcareous silty sand.

scholarly journals Responses of Soil Infiltration to Water Retention Characteristics, Initial Conditions, and Boundary Conditions

Land ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 361
Author(s):  
Lesheng An ◽  
Kaihua Liao ◽  
Chun Liu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Constant Pressure ◽  
Pressure Head ◽  
Estimation Methods ◽  
Initial Water Content ◽  
Initial Water ◽  
Cumulative Infiltration ◽  
Retention Characteristics

(1) Background: Simulation of soil water infiltration process and analysis of its influencing factors are important for water resources management. (2) Methods: In this study, the relative contributions of the soil water retention characteristics (SWRC) estimation, initial water content, and constant pressure head at upper boundary to the cumulative infiltration under various soil conditions were quantified based on the 1-D Richards’ equation and 900 scenarios. Scenario simulations were performed for two SWRC estimation methods (Jensen method and Rosetta); three different initial water contents (0.15, 0.20, and 0.25 cm3/cm3); five different constant pressure heads (0.5, 1, 2, 4, and 8 cm); and thirty soil samples with varying texture and bulk density. (3) Results: Rosetta representing the drying branch of the SWRC yielded higher simulated cumulative infiltration compared with the Jensen method representing the wetting branch of the SWRC. However, the Jensen method–predicted cumulative infiltration fluxes matched well with the measured values with a low RMSE of 0.80 cm. (4) Conclusions: The relative contribution of the SWRC estimation method to cumulative infiltration (19.1–72.2%) was compared to that of constant pressure head (14.0–65.5%), and generally greater than that of initial water content (2.2–29.9%). Findings of this study have practical significance for investigating the transport of water, nutrients, and contaminants in the unsaturated zone.

Research on the Soil Water Characteristic Curve and Prediction of Compacted Bentonite

2012 ◽  
Vol 518-523 ◽  
pp. 2785-2791
Author(s):  
Fa Cheng Yi ◽  
Zhe Wang ◽  
Min Juan Zhou
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Phase Method ◽  
Dry Density ◽  
Initial Water Content ◽  
Initial Water ◽  
Soil Water Characteristic Curve ◽  
Retention Characteristics ◽  
Stress States ◽  
The Impact

In this paper, the soil water characteristic curve (SWCC)of Xinjiang Altay bentonite under different stress states, different initial dry density and different initial water content has been tested by dialysis method and vapor phase method, and the impact of the various factors on the water retention characteristics of Xinjiang Altay bentonite has been analyzed comprehensively. The mercury intrusion porosimetry (MIP) test has been carried out on the soil sample, and then the SWCC is predicted by the Pore size distribution(PSD)curve which is got from the MIP test. Finally, the predicted SWCC is compared with the measured SWCC, and it shows that the predicted SWCC is close to the measured values, but there are deviations in the high suction.

Measurement of soil-water characteristic curves for fine-grained soils using a small-scale centrifuge

2002 ◽  
Vol 39 (5) ◽  
pp. 1209-1217 ◽  
Author(s):  
R M Khanzode ◽  
S K Vanapalli ◽  
D G Fredlund
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Small Scale ◽  
Characteristic Curves ◽  
Pressure Plate ◽  
Soil Water Characteristic Curve ◽  
Fine Grained ◽  
Soil Water Characteristic Curves ◽  
Plate Apparatus

Considerably long periods of time are required to measure soil-water characteristic curves using conventional equipment such as pressure plate apparatus or a Tempe cell. A commercially available, small-scale medical centrifuge with a swinging type rotor assembly was used to measure the soil-water characteristic curves on statically compacted, fine-grained soil specimens. A specimen holder was specially designed to obtain multiple sets of water content versus suction data for measuring the soil-water characteristic curve at a single speed of rotation of the centrifuge. The soil-water characteristic curves were measured for three different types of fine-grained soils. The three soils used in the study were processed silt (liquid limit, wL = 24%; plasticity index, Ip = 0; and clay = 7%), Indian Head till (wL = 35.5%, Ip = 17%, and clay = 30%), and Regina clay (wL = 75.5%, Ip = 21%, and clay = 70%). The soil-water characteristic curves for the above soils were measured in 0.5, 1, and 2 days, respectively, using the centrifuge technique for suction ranges from 0 to 600 kPa. Time periods of 2, 4–6, and 16 weeks were required for measuring the soil-water characteristic curves for the same soils using a conventional pressure plate apparatus. There is reasonably good agreement between the experimental results obtained by the centrifuge and the pressure plate methods. The results of this study are encouraging as soil-water characteristic curves can be measured in a reduced time period when using a small-scale centrifuge.Key words: unsaturated soils, soil-water characteristic curve, centrifuge technique, soil suction, matric suction, water content.

SOIL WATER CHARACTERISTIC CURVES OF COMPACTED KAOLIN FOR VARIOUS INITIAL MOISTURE CONTENT

2015 ◽  
Vol 76 (2) ◽  
Author(s):  
Muhammad Azril Hezmi ◽  
Radzuan Saari ◽  
Mohd Zakri Zahari ◽  
Rini Asnida Abdullah ◽  
Nor Zurairahetty Mohd Yunus ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Filter Paper ◽  
Unsaturated Soils ◽  
Initial Moisture Content ◽  
Great Influence ◽  
Water Retention Curve ◽  
Initial Water Content ◽  
Initial Water ◽  
The Relationship

The soil water characteristic curve (SWCC), also known as soil water retention curve (SWRC), describes the relationship between water content and soil suction in unsaturated soils. The importance of SWCC can be seen, as the relationship affects geotechnical properties such as shear strength, volume change, permeability and deformability of unsaturated soils. This paper presented a preliminary study on the effect of initial water content and the density on SWCC on unsaturated compacted kaolin. Filter paper technique was used for suction measurement on the unsaturated compacted kaolin soil. Filter paper was used to determine total suction and matric suction through contact and noncontact technique. The calibration curve was used to relate with the gravimetric water content obtained in filter paper with corresponding suction. A comparison on SWCC established through filter paper was also compared with that of the axis translation technique (pressure plate extractor). The study found that the initial water content and the density respectively, have great influence on the SWCC of compacted kaolin. However, the combined effect could be seen significantly at lower suction

Influence of initial water content and strain rate on remolded yield stress in marine clay

2021 ◽  
pp. 1-8
Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Yield Stress ◽  
Initial Water Content ◽  
Marine Clay ◽  
Initial Water
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