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.

scholarly journals Improving water retention capacity of an aeolian sandy soil with feldspathic sandstone

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lu Zhang ◽  
Jichang Han
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Sandy Soil ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Mu Us Sandy Land ◽  
Soil Water Characteristic Curves ◽  
High Suction ◽  
Feldspathic Sandstone

Abstract The Mu Us sandy land in China’s Shaanxi Province faces a critical water shortage, with its aeolian sandy soil endangering the regional eco-environment. Here we investigated the effects of feldspathic sandstone on water retention in an aeolian sandy soil from the Mu Us sandy land. Feldspathic sandstone and aeolian sandy soil samples were mixed at different mass ratios of 0:1 (control), 1:5 (T1), 1:2 (T2), and 1:1 (T3). Soil-water characteristic curves were determined over low- to medium-suction (1–1000 kPa) and high-suction (1000–140 000 kPa) ranges, by centrifuge and water vapor equilibrium methods, respectively. Results showed that the addition of feldspathic sandstone modified the loose structure of the aeolian sandy soil mainly consisting of sand grains. The van Genuchten model described well the soil-water characteristic curves of all four experimental soils (R2-values > 0.97). Soil water content by treatment was ranked as T2 > T3 > T1 > control at the same low matric suction (1–5 kPa), but this shifted to T2 > T1 > T3 > control at the same medium- to high-suction (5–140 000 kPa). T2 soil had the largest saturated water content, with a relatively high water supply capacity. This soil (T2) also had the largest field capacity, total available water content, and permanent wilting coefficient, which were respectively 17.82%, 11.64%, and 23.11% higher than those of the control (P-values < 0.05). In conclusion, adding the feldspathic sandstone in an appropriate proportion (e.g., 33%) can considerably improve the water retention capacity of aeolian sandy soil in the study area.

scholarly journals Microstructure of Compacted Loess and Its Influence on the Soil-Water Characteristic Curve

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao Xie ◽  
Ping Li ◽  
Xiaokun Hou ◽  
Tonglu Li ◽  
Guowei Zhang
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Great Influence ◽  
Matric Suction ◽  
Constitutive Relationship ◽  
Wetting And Drying ◽  
Soil Water Characteristic Curve ◽  
High Suction ◽  
Water Contents ◽  
Compacted Loess

Soil-water characteristic curve (SWCC) is a key constitutive relationship for studying unsaturated soil, and as is known, microstructure of the soil has great influence on the mechanical behaviour of the soil. In this study, the wetting and drying soil-water characteristic curves (SWCCs) of loess compacted at three different water contents were measured using the filter paper method. And microproperties of compacted loess were obtained by the mercury intrusion method (MIP) and scanning electron microscope (SEM). Results show that the compaction water contents have significant influence on the SWCC and microstructure. The pore size distribution (PSD) curves have great differences in macropore range and are similar in micropore range. Loess compacted at optimum and dry of optimum are generally connected, while there are certain number of nonintruded pores in loess compacted at wet of optimum. The SWCC curves vary significantly in low suction (ua − uw < 1000 kPa) and tend to converge together in high suction (ua − uw ≥ 1000 kPa). Hysteresis in the SWCCs is more obvious for loess compacted at optimum and dry of optimum in the matric suction of 0∼100 kPa; however, there is a pronounced hysteresis for loess compacted at wet of optimum in full matric suction range. The characteristic of the SWCCs including their hysteresis can be well interpreted from the loess microstructure.

Study on Unsaturated Mechanism of Loess Compaction

2011 ◽  
Vol 368-373 ◽  
pp. 2960-2965
Author(s):  
Qing Feng Lv ◽  
Jing Wen Zhao ◽  
Sheng Xin Wang ◽  
Yan Xu Zhao
Keyword(s):  
Moisture Content ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Pore Space ◽  
Characteristic Curve ◽  
Dry Density ◽  
Physical Factors ◽  
Mineral Component ◽  
Space Topology ◽  
Soil Water Characteristic Curve

The soil-water characteristic curve is an important constitutive feature of unsaturated soils, defining the relationship between the soil suction and moisture content. Mineral component and pore space topology are the most important physical factors affecting the soil-water characteristic, and that dry density synthetically reflects the mineral component and pore space topology. Compaction is a classical application involving unsaturated soil, and dry density represents the pore structure at special moisture content. Soil water characteristic curve for compacted loess is studied by test, and the effect of dry density on soil water characteristic curve is discussed. Based the soil-water characteristic curve and compaction curve, mechanism of compaction is explained. Research results show that the soil-water characteristic curves for all dry density soil intersect at the point, which is optimize moisture content, and suction is the most important factor affecting the compaction.

Research on Soil-Water Characteristic Curve of Unsaturated Mixed-Soil in West Sichuan

2013 ◽  
Vol 353-356 ◽  
pp. 996-1000
Author(s):  
Wei Guang Zhou ◽  
Yu Long Bao ◽  
Hong Bin Zhou
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Clay Content ◽  
Dry Density ◽  
Residual Moisture ◽  
Soil Water Characteristic Curve ◽  
Physical Form ◽  
Physical Composition

A series of tests are conducted to get the physical composition, physical form and the soil-water characteristic curve in different dry density of three typical composite unsaturated soils in west Sichuan. Test data shows that the variation of physical composition, particle size and dry density can result in great change of soil-water characteristic curve. The bigger the dry density is, the more hydrophilic mineral the soil has, the more gentle the soil-water characteristic curve is, and the higher its residual moisture content is. In addition, under the same water content, matrix suction decreases with less clay content and more content. For the three typical composite unsaturated soils, with relatively bigger water content, the change of soil-water characteristic curve resulting from variation of dry density is less, but with the water content getting smaller, the change becomes clearer.

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.

Experimental Research of Matrix Suction of the Unsaturated Red Clay

2014 ◽  
Vol 919-921 ◽  
pp. 835-838 ◽  
Author(s):  
Wen Feng Zhao ◽  
Long Li ◽  
Yu Hang Xiao
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Matric Suction ◽  
High Water Content ◽  
Dry Density ◽  
Red Clay ◽  
Soil Water Characteristic Curve ◽  
Matrix Suction ◽  
The Impact

Matric suction has great impact on the strength of soil. Some physico-mechanical indexes, such as the water content, dry density of soil, have close relationship with the matric suction. The experiments were conducted in the laboratory to study the relationship between the matric suction, the water content and dry density of unsaturated red clay. The filter paper method was used to get the soil-water characteristic curve of the unsaturated red clay. The results show that: water content has great impact on matrix suction. The soil-water characteristic curve can be divided into three stages. In low water content area, matrix suction decreases rapidly with the increase of water content.Then, the rate of change slows down after the inflection point. Matrix suction increases obviously with the increase of dry density under the condition of low water content, but the impact disappears under high water content. So the matrix suction is affected by dry density and water content.

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