scholarly journals Experimental Study on the Effect of Key Factors on the Soil–Water Characteristic Curves of Fine-Grained Tailings

2021 ◽  
Vol 9 ◽  
Author(s):  
Baofeng Cao ◽  
Yakun Tian ◽  
Rong Gui ◽  
Yong Liu
Keyword(s):  
Moisture Content ◽  
Soil Water ◽  
Dry Density ◽  
Key Factors ◽  
Fine Grained ◽  
Volumetric Moisture Content ◽  
The Matrix ◽  
Van Genuchten Model ◽  
Matrix Suction ◽  
Water Holding

The soil–water characteristic curve (SWCC) is an essential parameter for studying the mechanical properties of unsaturated tailings, and it plays an important role in stability assessment and prediction of unsaturated tailings dams. In this paper, the matrix suction was measured indirectly by a filter paper-based method to investigate the effects of key factors (gradation, temperature, and initial dry density) on the soil–water characteristic curves of fine-grained tailings, and the Van Genuchten model was adopted to obtain the empirical equation of SWCC and to verify the accuracy of experimental results. The results showed the following: 1) the Van Genuchten model fits well the relationship between matric suction and volumetric moisture content of fine-grained tailings, indicating that experimental data determined by filter paper-based method is accurate and appropriate; 2) at the same volumetric moisture content, the matrix suction increased with decreasing average particle size, and the decrease in temperature will increase the matrix suction and water-holding capacity of fine-grained tailings, and the matrix suction of the tailings in summer is 38.3% lower than that in winter under the natural volumetric moisture content (14.0%); 3) when the saturation degree of fine-grained tailings is less than 60%, the greater the initial dry density, the better the water-holding capacity and matrix suction.

Influence of Soil Texture on Soil-Water Characteristic Curves of Different Sandy Loam Layers

2014 ◽  
Vol 955-959 ◽  
pp. 3607-3610
Author(s):  
Li Zhu Hou ◽  
Jochen Wenninger ◽  
Xu Jie Li
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Soil Moisture Content ◽  
Sandy Loam ◽  
Soil Water Storage ◽  
Characteristic Curves ◽  
Van Genuchten Model ◽  
Soil Water Characteristic Curves ◽  
Matrix Suction

Characteristic curves of soil moisture, between water content and matrix suction, are the basis for solving the problems of water flow and solute movement in soils. The soil–water characteristics of five layers of depths, 0–12 cm, 12–24 cm, 24–36 cm, 36–48 cm, and 48–60 cm, were measured for a sandy loam soil from Daxing District of Beijing in the northern part of the North China Plain by a pressure membrane apparatus. Curves were fitted using the Van Genuchten model. The fit between measured data and modeled results was excellent. The soil-water characteristic curves showed the typical Sshape of the Van Genuchten model. Matrix suction decreased with an increase in soil moisture; at low suctions, soil moisture content changed to a greater extent with suction, but at high suction, changes in soil moisture content with changes in suction were small. Clay content was proportional to soil water storage capacity and was inversely related to the speed of dehydration.

Experimental Study on Gravel Soils of Matrix Suction

2013 ◽  
Vol 275-277 ◽  
pp. 310-315 ◽  
Author(s):  
Hong Mei Tang ◽  
Pei Wei Liao ◽  
Lin Feng Wang ◽  
Hong Kai Chen
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Curved Surface ◽  
Soil Water Characteristic Curve ◽  
Content Change ◽  
Two Factors ◽  
The Matrix ◽  
Matrix Suction

Soil-water characteristic curve（SWCC）is closely relevant to two main factors which are structure and moisture content. According to the two factors the values of matrix suction of 45 groups experimental specimens within different moisture content and soil -stone ratio of unsaturated soil are get through filter paper method. Date analysis shows that relation between matrix suction and soil-stone ratio at different moisture states is of different characteristics. Relation between matrix suction and water content is notably nonlinear. Distribution of matrix suction is curved surface in the moisture and soil-stone ration state space which is the function of water content and soil-stone ratio, in which the axial plan is parallel to the axis of soil-stone ratio.At low water content,the matrix suction on the moisture content change is very sensitive, at high moisture content and closed to saturation stage matrix suction hardly changes along with water content and soil-stone ratio change. The curved surface which Located in the middle section ,the matrix suction on the change of water content are more sensitive, reduced with water content increasing; and in this phase the matrix suction is insensitive to the variation of soil-stone ratio. Finally, it is concluded that the saturation to describe the soil water characteristic curve is a bad choice, with moisture to depict the so. In contrast, directly using the water content to describe the soil water characteristic curve is better.

Model for predicting resilient modulus of unsaturated subgrade soil using soil-water characteristic curve

2015 ◽  
Vol 52 (10) ◽  
pp. 1605-1619 ◽  
Author(s):  
Zhong Han ◽  
Sai K. Vanapalli
Keyword(s):  
Moisture Content ◽  
Soil Water ◽  
Resilient Modulus ◽  
Characteristic Curve ◽  
Optimum Moisture Content ◽  
Model Parameters ◽  
Soil Water Characteristic Curve ◽  
Subgrade Soils ◽  
Fine Grained ◽  
Proposed Model

Soil suction (ψ) is one of the key factors that influence the resilient modulus (MR) of pavement subgrade soils. There are several models available in the literature for predicting the MR–ψ correlations. However, the various model parameters required in the existing models are generally determined by performing regression analysis on extensive experimental data of the MR–ψ relationships, which are cumbersome, expensive, and time-consuming to obtain. In this paper, a model is proposed to predict the variation of the MR with respect to the ψ for compacted fine-grained subgrade soils. The information of (i) the MR values at optimum moisture content condition (MROPT) and saturation condition (MRSAT), which are typically determined for use in pavement design practice; (ii) the ψ values at optimum moisture content condition (ψOPT); and (iii) the soil-water characteristic curve (SWCC) is required for using this model. The proposed model is validated by providing comparisons between the measured and predicted MR–ψ relationships for 11 different compacted fine-grained subgrade soils that were tested following various protocols (a total of 16 sets of data, including 210 testing results). The proposed model was found to be suitable for predicting the variation of the MR with respect to the ψ for all the subgrade soils using a single-valued model parameter ξ, which was found to be equal to 2.0. The proposed model is promising for use in practice, as it only requires conventional soil properties and alleviates the need for experimental determination of the MR–ψ relationships.

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.

Use of Time Domain Reflectometry to Estimate Moisture and Density of Unbound Road Materials: Laboratory Calibration and Field Investigation

2017 ◽  
Vol 2655 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Habibullah Bhuyan ◽  
Alexander Scheuermann ◽  
Didier Bodin ◽  
Rolf Becker
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Time Domain ◽  
Voltage Drop ◽  
Base Material ◽  
Field Investigation ◽  
Time Domain Reflectometry ◽  
Pavement Performance ◽  
Dry Density ◽  
Volumetric Moisture Content

Soil moisture content and dry density of unbound granular pavement materials are important properties for compaction control that influence pavement performance under cyclic loading. Under these loading conditions, increasing moisture content can accelerate significant changes in density. Time domain reflectometry (TDR) is a method for measuring the moisture content and density of soils with rod probe sensors. This paper introduces new calibration functions for TDR measurements using these rod probe sensors embedded in the soil. TDR measurements were taken in the laboratory for a typical road base material at two basically different conditions: at constant moisture content with different dry densities and at constant dry density with different moisture contents. In this study, a relationship was developed between the voltage drop occurring for the passage of an electromagnetic wave through the soil and the bulk density. The permittivity of the soil sample obtained from the travel time of TDR signals was used to calculate the volumetric moisture content. Finally, the gravimetric moisture content was obtained from the volumetric moisture content and bulk density relationship. For the validation of the calibration functions, rod probe sensors were installed in a road to obtain in situ moisture content and density under field conditions. Laboratory results indicate that the calibration functions are independent of moisture and density, and the field test shows the applicability of the method. The newly developed calibration functions allow for the monitoring of the long-term pavement performance, leading to a better understanding of the time-dependent evolution of, for example, rutting of roads.

Experimental Study on Compaction and Strength Characteristic of Wetland Fine Grained Soil

2012 ◽  
Vol 256-259 ◽  
pp. 336-339
Author(s):  
Hong Xia Yang
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
High Moisture ◽  
Compacted Soil ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Work Effect

Through indoor the compaction test and unconfined compressive strength of compacted soil samples and CBR strength test, analyzes compaction characteristics of wetland fine grained soil and the change rule of compacted strength with compaction work and moisture content.The results show that under the same compaction work effect, when the soil moisture content is less than optimum moisture content,along with the increase of moisture content, dry density increases, when the soil moisture content is greater than the optimum moisture content, along with the increase of moisture content, dry density decreases and to a larger extent.When the compaction work is bigger, the soil dry density is bigger, the compaction strength is higher and the optimum moisture content is smaller.Strength decreases when under high moisture content condition, CBR value is relatively stable in the wet side of optimum moisture content.

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.

scholarly journals Effect of Growth Factors on the Production of Mycelium-based Biofoam

2021 ◽  
Author(s):  
Noor Idayu Mohd Nashiruddin ◽  
Kai Shin Chua ◽  
Azmi Fadziyana Mansor ◽  
Roshanida A. Rahman ◽  
Jau Choy Lai ◽  
...  
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Moisture Content ◽  
Rice Husk ◽  
Incubation Temperature ◽  
Fungal Mycelium ◽  
Dry Density ◽  
Mycelium Growth ◽  
Promising Alternative ◽  
The Matrix

Abstract Mycelium-based biofoam has the potential to become an alternative to petroleum-polymeric based-foam by utilising fungal mycelium and lignocellulosic material as the matrix and substrate, respectively. The lignocellulosic materials, which were rice husk, sawdust, and sugarcane bagasse, which is crucial for the production of biofoam, were tested as a substrate for Pleurotus ostreatus mycelium growth during the screening procedure. Three growth factors were varied during mycelium-based biofoam production: incubation temperature, spawn loading, and moisture content. In this study, rice husk was the ideal substrate in the production of mycelium biofoam compared to other fungi. The inhibition of P. ostreatus mycelium growth at 30°C incubation temperature was due to decay and contamination. On the other hand, by varying the growth factor of mycelium biofoam on rice husk, the optimum dry density of mycelium-biofoam was observed at 50% (w/w) moisture content (1.07 g/cm3), while the optimum compressive strength was observed at 40% (w/w) spawn loading (1.350 MPa). These results showed that varying the growth factor could influence the mechanical behaviour of the material. The morphology of the biofoam was also observed through a scanning electron microscope (SEM). Short and highly entangled tube-like structures and compact filaments forming a material were seen, responsible for the lightness characteristic of the material. The functional group of the biofoam was also determined using a Fourier transform infrared (FTIR) spectrophotometer. A new band of proteins and lipids was detected at 1633 cm−1 and 3280 cm−1 in the biofoam. It clearly shows that the chemical nature of feeding substrate responsible for the changes of material spectra. Therefore, this study highlighted that the biodegradable mycelium biofoam of P.ostreatus using rice husk as a substrate is a promising alternative to polymeric foam.

scholarly journals Experimental Study on the Effect of Water on the Properties of Cast In Situ Foamed Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wenhui Zhao ◽  
Qian Su ◽  
Wubin Wang ◽  
Lele Niu ◽  
Ting Liu
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Moisture Content ◽  
Water Level ◽  
Immersion Time ◽  
Drying Shrinkage ◽  
Dry Density ◽  
Volumetric Moisture Content ◽  
Foamed Concrete

This study aims to investigate the effect of water on the properties of cast in situ foamed concrete with a dry density of 300–800 kg/m3 (100 kg/m3 is a gradient). Firstly, the shrinkage deformation with the curing time and the volumetric moisture content is studied by the drying shrinkage test and improved drying shrinkage test. Secondly, the influence of volumetric moisture content on mechanical properties is assessed. At last, the effects of immersion time and immersion type on the mechanical properties of foamed concrete are studied by considering the water-level conditions. The achieved results show that the shrinkage deformations increase with the curing time for the drying shrinkage test and the improved drying shrinkage test, while the variations are different. The shrinkage deformation increases with the decrease of volumetric moisture content for six dry densities of foamed concrete. Besides, it gradually changes in the early stage, while it changes fast in the later stage. The compressive strength and elastic modulus decrease with the increase of volumetric moisture content for each density. For the water-level unchanged condition, the compressive strength and elastic modulus initially decrease and then slowly increase with the increase of the immersion time. For the water-level changed condition, the compressive strength and elastic modulus of foamed concrete decrease with the increase of immersion time for each dry density, and the rate of early attenuation is high, whereas the rate of later attenuation is limited.

Experimental Study on Shear Strength of West Sichuan Unsaturated Mixed-Soil

2013 ◽  
Vol 353-356 ◽  
pp. 772-778 ◽  
Author(s):  
Kai Cui ◽  
Bang Wen Huang
Keyword(s):  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Mineral Water ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Cohesive Force ◽  
Dry Density ◽  
Control Matrix ◽  
Matrix Suction

By controlling moisture content to control matrix suction indirectly, three typical unsaturated remolded mixed-soil from west Sichuan are studied by the consolidated untrained triaxial shear test .The test data show that for different kinds of soil samples, the sample with less amount of clay and high content of quartz has bigger internal friction angle relatively, and the sample with hydrophilic mineral and high content of clay has bigger cohesive force. Meanwhile, for the sample without or less hydrophilic mineral, cohesive force is affected mainly by water content, and for the sample with large content of hydrophilic mineral, water content and dry density affect cohesive force together. For a certain sample, the variation of moisture content and dry density affects internal friction angle less, while affects cohesive force more. In addition, the change of internal friction angle resulting from the variation of matrix suction is less, and cohesive force increases as matrix suction increases.

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