scholarly journals Measurement and Uniform Formulation of Soil-Water Characteristic Curve for Compacted Loess Soil with Different Dry Densities

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yu Wang ◽  
Tonglu Li ◽  
Ping Li ◽  
Yulu Lei ◽  
David D. Lawrence
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Loess Soil ◽  
Measured Data ◽  
Dry Density ◽  
Compacted Soil ◽  
Water Characteristics ◽  
Soil Water Characteristic Curves ◽  
High Suction ◽  
Paper Method

To investigate the effect of dry density on the soil-water characteristics of compacted soil, loess used as filling in the land-making project of the Yan’an new district was collected and compacted to five initial dry densities of 1.40, 1.50, 1.60, 1.70, and 1.80 g/cm3, respectively. The soil-water characteristic curves (SWCCs) of all specimens in the range of 0–105 kPa were measured using the filter paper method. The measured data were fitted using the Fredlund and Xing equation for each initial dry density. The SWCCs have obvious differences in a suction range below 100 kPa and overlap when the suction range is higher. This suggests that the SWCC of compacted soil is independent of the initial dry density in the high suction range, but the correlation with the initial dry density exists in the low suction range. Therefore, the correlation functions of the parameters in the Fredlund and Xing equation with respect to the initial dry density were regressed, respectively. By substituting these functions into the Fredlund and Xing equation, the state surface function of θ w − ψ − ρ d was obtained and can reflect the SWCCs of all densities of the filled soil to support the further investigation of the unsaturated behavior of compacted soil.

scholarly journals A study on the effect of pore and particle distributions on the soil water characteristic curve of compacted loess

2021 ◽  
Author(s):  
Yu Wang ◽  
Tonglu Li ◽  
Chenxi Zhao ◽  
Xiaokun Hou ◽  
Ping Li ◽  
...  
Keyword(s):  
Soil Water ◽  
Construction Projects ◽  
Characteristic Curve ◽  
Loess Soil ◽  
Northwest China ◽  
Water Infiltration ◽  
Dry Density ◽  
Particle Distributions ◽  
Water Characteristics ◽  
Compacted Loess

Abstract Compacted loess soil is used as a geo-material in many engineering projects such as building foundations and highway embankments. Water infiltration characteristics and post settlement of the compacted loess in large construction projects of Northwest China have received increasing attention from researchers and investors. These behaviors are closely related to the soil water characteristics. This study aims to investigate the soil water characteristic curves (SWCCs) of compacted loess soil with different dry densities and to reveal the responsible micro-mechanisms for soil water characteristics. Loess soil collected from the new district of Yan'an City, China, is prepared into five dry density groups. The SWCC of each group in the suction range of 0–100,000 kPa is measured using the filter paper method (FPM). Two-dimensional (2D) images and the pore size distribution (PSD) curves of the specimens are tested by scanning electron microscopy (SEM) and the mercury pressure method (MIP), respectively. The results of this study highlight that the compaction behavior mainly influences the pores with a radius ( r ) in the range of 1–10 μm, and has no influence on the pores of r < 0.5 μm. The particle shapes among the five dry densities groups are similar. The characteristics of the PSD curves of the compacted loess soil correspond well to the SWCCs. The suction of the SWCCs increases with increasing dry density in the lower suction range of 0–100 kPa. In contrast, suction among the five dry density groups is almost identical in the suction range exceeding 100 kPa. The results of the study are helpful to understand the SWCC and microstructure characteristics of compacted loess with different dry densities.

Bayesian Estimation of Soil-Water Characteristic Curves

2021 ◽  
Author(s):  
Jie Zhang ◽  
Shuai Yang ◽  
Lulu Zhang ◽  
Mingliang Zhou
Keyword(s):  
Soil Water ◽  
Bayesian Model ◽  
Characteristic Curve ◽  
Measurement Data ◽  
Bayes Theorem ◽  
Empirical Method ◽  
Measured Data ◽  
Suggested Method ◽  
Empirical Methods ◽  
Soil Water Characteristic Curves

The soil-water characteristic curve (SWCC) is a significant prerequisite for studying the mechanical properties of unsaturated soil. As experimental measurement of the SWCC is time-consuming, empirical methods have been suggested to estimate the SWCC. However, the uncertainty associated with SWCC can be substantial. In this paper, a hybrid method based on Bayes’ theorem is suggested to estimate the SWCC, where an empirical method can be used to provide prior knowledge about the SWCC, and a limited quantity of measured data is used to update the SWCC. The Bayesian model is then solved with a Markov Chain Monte Carlo simulation. Through the suggested method, the valuable information provided by the empirical method can be combined with the measurement data. The suggested method can not only provide the best estimate about the SWCC, but also account for the associated uncertainty. Also, the effect of more measured points on the estimation of SWCC can be quantified. The suggested method provides a practical means to estimate the SWCC using a limited amount of data.

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.

Test Study on Effects of Temperature, Sand Mix Ratios and Dry Density on Soil Water Characteristic Curves of Bentonite-Sand Mixtures

2014 ◽  
Vol 580-583 ◽  
pp. 359-363
Author(s):  
Xiang Wei Fang ◽  
Chun Ni Shen ◽  
Chun Hai Li ◽  
Long Wang
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Water Retention Capacity ◽  
Dry Density ◽  
Retention Capacity ◽  
Sand Mixture ◽  
Soil Water Characteristic Curve ◽  
Test Study ◽  
Effects Of Temperature ◽  
High Suction

A series of tests on the soil water characteristic curve through moisture balance method were conducted to study the effects of temperature, sand mix ratios and dry density on the soil water characteristic curve of bentonite-sand mixture. The test results show that with the increase of temperature, the water retention capacity of the mixture significantly decreased. Within the test control suction range, sand mix ratios at the low suction had obvious effects on the soil water characteristic curve and at high suction the effects gradually decreased. Dry density had no effects on the soil water characteristic curve of bentonite-sand mixture. In accordance with the test data, an experience model of soil water characteristic curve of bentonite-sand mixtures considering temperature and sand mix ratios is established.

Measurement of Soil Suction and Soil-Water Characteristics of Bentonite-Sand Mixtures

2010 ◽  
Author(s):  
Pan Hu ◽  
Qing Yang ◽  
Maotian Luan
Keyword(s):  
Soil Water ◽  
Vapor Phase ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Phase Method ◽  
Soil Suction ◽  
Compacted Bentonite ◽  
Water Characteristics ◽  
Wide Range ◽  
High Level

The soil-water characteristic curve (SWCC) is a widely used experimental means for assessing fundamental properties of unsaturated soils for a wide range of soil suction values. The study of SWCC is helpful because some properties of unsaturated soils can be predicted from it. Nowadays, much attention has been paid to the behaviours of highly compacted bentonite-sand mixtures used in engineering barriers for high level radioactive nuclear waste disposal. It is very important to study the various performances of bentonite-sand mixtures in order to insure the safety of high-level radioactive waste (HLW) repository. After an introduction to vapor phase method and osmotic technique, a laboratory study has been carried out on compacted bentonite-sand mixtures. The SWCC of bentonite-sand mixtures has been obtained and analyzed. The results show that the vapor phase method and osmotic technique is suitable to the unsaturated soils with high and low suction.

Soil-water characteristics of compacted sandy and cemented soils with and without vegetation

2015 ◽  
Vol 52 (9) ◽  
pp. 1331-1344 ◽  
Author(s):  
W.M. Yan ◽  
Guanghui Zhang
Keyword(s):  
Soil Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rapid Development ◽  
Characteristic Curve ◽  
Degree Of Saturation ◽  
Material Density ◽  
Water Characteristics ◽  
Field And Laboratory Conditions ◽  
Humidity Monitoring

Experiments were undertaken to study the soil-water characteristics of compacted sandy soil (SS) and cemented soil (CS) in field and laboratory conditions. The influence of vegetation and material density on the development of negative pore-water pressure (PWP) and degree of saturation (Sr) in the studied materials was investigated. The field planting experiments demonstrated a promising survival rate of Schefflera heptaphylla in both types of material, while the (SS) promoted better growth of the seedlings than the cemented one. In the field study, PWP and Sr of the compacted SS responded noticeably and promptly to natural drying–wetting cycles. However, the responses in the CS were relatively mild. When subjected to the same drying–wetting cycles, PWP responded more slowly and to a smaller magnitude compared with that of the uncemented counterpart. In addition, Sr changed little in CS. An increase in the density of the SS promoted rapid development of negative PWP, while an opposite trend was observed for CS. Attempts have been made to explain the observations from the perspectives of material permeability and change in water content during a drying period in both soil types. Furthermore, in SS, the development of PWP (with a measurement limit of −90 kPa) was minimally affected by the presence of vegetation, while vegetation noticeably helped the development of negative PWP in CS. Bounds of the soil-water characteristic curve (SWCCs) of the studied materials were presented based on estimates from the drying and wetting scanning curves derived from the field monitoring. A corresponding laboratory study was carried out in an environmental chamber with controllable temperature and humidity. Monitoring results from the laboratory agreed qualitatively with those obtained from the field.

The Trial Research of Soil-Water Characteristic Curves of Unsaturated Soil and its Engineering Application

2012 ◽  
Vol 170-173 ◽  
pp. 3050-3053
Author(s):  
Cui Ran Liu ◽  
Jin Jun Guo
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Permeability Coefficient ◽  
Characteristic Curve ◽  
Engineering Application ◽  
Engineering Properties ◽  
Confining Pressures ◽  
Soil Water Characteristic Curves ◽  
Matrix Suction ◽  
Water Contents

With the improved triaxial equipment, the tests of research of the relationships between matrix suction and water content are performed And based on the test data, the curves between matrix suction and water contents under different confining pressures are drawn and the change rule between them are analyzed. And then the function between them is simulated out. Through the soil-water characteristic curve, the permeability coefficient of unsaturated soil can be calculated and the shear strength of unsaturated soil can be predicted. These results are important to research the engineering properties of unsaturated soil.

Soil Water Characteristic Curve for a Granite Residual Soil: Experimental and Numerical Results

2011 ◽  
Vol 312-315 ◽  
pp. 1172-1177 ◽  
Author(s):  
A. Topa Gomes ◽  
A. Viana Da Fonseca ◽  
A. Silva Cardoso
Keyword(s):  
Experimental Data ◽  
Soil Water ◽  
Characteristic Curve ◽  
Residual Soil ◽  
Seepage Analysis ◽  
Soil Water Characteristic Curve ◽  
Granite Residual Soil ◽  
Definition Of ◽  
Paper Method ◽  
Geotechnical Problems

The seepage analysis in geotechnical problems, namely in excavations, was typically performed assuming saturated conditions in the ground. It is now know that the flow in the non saturated part of the ground assumes also relevant importance and hence it is vital to characterize its behaviour. The Soil Water Characteristic Curve (SWCC) of the soil is probably the most important parameter in defining this behaviour and particularly for estimating the permeability of the soil. This paper presents the definition of the SWCC for a granite residual soil using pressure plates and the filter paper method. Based on experimental data some equations are adjusted and the results obtained are discussed. At the end of the paper some predictions of the non saturated permeability of the ground are also performed.

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