scholarly journals Evaluation of Collapsibility of Compacted Loess Based on Resistivity Index

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yongpeng Nie ◽  
Wankui Ni ◽  
Haiman Wang ◽  
Kangze Yuan ◽  
Wenxin Tuo ◽  
...  
Keyword(s):  
Water Content ◽  
New Method ◽  
Dry Density ◽  
Electrical Parameters ◽  
Potential Threat ◽  
Resistivity Index ◽  
Engineering Construction ◽  
Critical Water Content ◽  
Safety And Stability ◽  
Compacted Loess

Recently, a lot of engineering constructions have been carried out in the Loess Plateau of China. However, the collapsibility of compacted loess as a filler poses a potential threat to the safety and stability of buildings. To address this threat, the scientific evaluation of the collapsibility of compacted loess has become a key to engineering construction. This study, therefore, tested the resistivity of compacted loess under varying conditions of water content, dry density, and its collapsibility coefficient under a pressure of 200 kPa. The correlation between collapsibility and electrical parameters was determined, and based on the resistivity, a new method to evaluate the collapsibility of the compacted loess is proposed. The results show that the resistivity of compacted loess decreases with an increase in water content and dry density and that the effect of water content is more significant. There is a critical water content value that causes the resistivity decay rate to slow down. The collapsibility coefficient also decreases with an increase in water content and dry density, and under the same dry density or same water content, the collapsibility coefficient and resistivity are positively correlated. According to the normalized resistivity value ρ / ρ w , the relative collapsibility coefficient δ s /0.015, and the water content ω obtained in the experiment, a collapsibility coefficient prediction model based on the resistivity of compacted loess was established. Using resistivity to evaluate the collapsibility of loess is nondestructive and provides a new method to accurately and quickly evaluate the collapsibility of compacted loess.

Test Investigation on Mechanical of Unsaturated Loess

2012 ◽  
Vol 204-208 ◽  
pp. 22-27
Author(s):  
Yan Zhu ◽  
Yun Xu Chen
Keyword(s):  
Water Content ◽  
Horizontal Plane ◽  
Mechanical Characteristics ◽  
Loess Soil ◽  
Dry Density ◽  
One Dimensional ◽  
Test Investigation ◽  
Unsaturated Loess ◽  
Test Result ◽  
Compacted Loess

Compression and collapse of unsaturated compacted loess are studied by using dry density and water content which easily controlled in engineering, the controlling range of dry density and water content are confirmed respectively. Then the deformation of compression and collapse and the frequency of engineering damager occurrence can be decreased. In addition, the mechanical characteristics of loess in different directions may differ because the loess was consolidated only under the condition of its upper weight of soil and load. The conventional mechanical experiments, including one-dimensional compress and collapse test, were conducted with the specimen of loess soil in different angle from the original horizontal plane. The test result shows that the loess is anisotropic

scholarly journals Prediction of Soil-Water Characteristic Curve of Compacted Loess With Different Dry Densities Based on Nuclear Magnetic Resonance

2021 ◽  
Author(s):  
kangze yuan ◽  
Wan kui Ni ◽  
Xiang-Fei LV ◽  
Xiang-ning Li ◽  
Hai-man Wang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Content ◽  
Soil Water ◽  
Pore Volume ◽  
Dry Density ◽  
Residual Water ◽  
Residual Water Content ◽  
Compacted Loess ◽  
Nuclear Magnetic

Abstract Accurate determination of soil-water characteristic (SWCC) is of great importance for understanding the mechanical properties of unsaturated loess. In this study, the compacted loess columns with different dry densities were prepared. Moisture sensor, water potential sensor and nuclear magnetic resonance (NMR) were used to investigate the SWCC and NMR signals intesity of compacted loess under different dry densities. It has been found that with increasing dry density, the saturated water content and the residual water content gradually decreases, but the decrease in residual water content is smaller, and both can establish a linear relationship with dry density. The NMR results showed that the compacted loess pore volume gradually decreased with increasing dry density. When the dry density increased from 1.45 g/cm3 to 1.55 g/cm3, the pore volume of compacted loess decreased by 14.7%, while when the dry density increased from 1.55 g/cm3 to 1.65 g/cm3, the pore volume of compacted loess decreased by 13.2%. The Van Genuchten (VG) model was used to fit the NMR results and SWCC, and a good corresponding relationship was found between the parameters. Therefore, according to the cumulative NMR intensity parameters, SWCC was predicted under different dry densities and the effect was found very well.

Research on Shear Strength of Compacted Loess

2013 ◽  
Vol 448-453 ◽  
pp. 1284-1288 ◽  
Author(s):  
Juan Juan Wang ◽  
Jun Tao Deng ◽  
Song Lin Wu
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Dry Density ◽  
Dam Foundation ◽  
Direct Shear Tests ◽  
Strength Formula ◽  
Compacted Loess

Compacted loss widely used in the construction, such as embankment, dam, foundation backfill and other projects. Influenced by rainfall factors, the moisture content of compacted loess often vary so the shear strength will also changed. This paper studies the shear strength parameters of compacted loess through direct shear tests. In the dry density under the same conditions, the cohesion, internal friction angle of compacted loess decreases with the increase of water content. Summed cohesion and water content showed a quadratic parabola and internal friction angle and water content was also found quadratic parabola; further considering the effects of water content and dry density of compacted loess got shear strength formula. Shear strength formula.

Determination of water content in municipal sludge by multiple headspace extraction gas chromatography

2021 ◽  
Vol 13 (6) ◽  
pp. 796-800
Author(s):  
Ting Zhao ◽  
Zhanbo Hu ◽  
Xin-Sheng Chai ◽  
Yukai Zheng ◽  
Binxin Xu ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Water Vapor ◽  
Water Content ◽  
New Method ◽  
Municipal Sludge ◽  
Headspace Extraction ◽  
Multiple Headspace Extraction ◽  
Sample Vial

This paper reports a new method for the determination of sludge water content by a multiple headspace extraction gas chromatographic (MHE-GC) method. It is based on the water vapor signals in the sample vial from the first five extractions.

Hydraulic Conductivity of Compacted Tropical Clay Treated with Rice Husk Ash

2011 ◽  
Vol 367 ◽  
pp. 63-71 ◽  
Author(s):  
Adrian O. Eberemu ◽  
Agapitus A. Amadi ◽  
Joseph E. Edeh
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Rice Husk ◽  
Industrial Waste ◽  
Rice Husk Ash ◽  
Waste Product ◽  
Dry Density ◽  
Waste Containment ◽  
Hydraulic Behaviour ◽  
Waste Containment Systems

Laboratory study on compacted tropical clay treated with up to 16% rice husk ash (RHA), an agro-industrial waste; to evaluate its hydraulic properties and hence its suitability in waste containment systems was carried out. Soil-RHA mixtures were compacted using standard Proctor, West African Standard and modified Proctor efforts at-2, 0, 2 and 4% of optimum moisture content (OMC). Compacted samples were permeated and the hydraulic behaviour of the material was examined considering the effects of moulding water content, water content relative to optimum, dry density and RHA contents. Results showed decreasing hydraulic conductivity with increasing moulding water content and compactive efforts; it also varied greatly between the dry and wet side of optimum decreasing towards the wet side. Hydraulic conductivity generally decreased with increased dry density for all effort. Hydraulic conductivity increased with rice husk ash treatment at the OMC; but were within recommended values of 1 x 10-7 cm/s for up to 8% rice husk ash treatment irrespective of the compactive effort used. This shows the suitability of the material as a hydraulic barrier in waste containment systems for up to 8% rice husk ash treatment and beneficial reuse of this agro-industrial waste product.

scholarly journals Thermal Conductivity of Compacted GO-GMZ Bentonite Used as Buffer Material for a High-Level Radioactive Waste Repository

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yong-Gui Chen ◽  
Xue-Min Liu ◽  
Xiang Mu ◽  
Wei-Min Ye ◽  
Yu-Jun Cui ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Radioactive Waste ◽  
Water Content ◽  
Radioactive Waste Disposal ◽  
Dry Density ◽  
Gmz Bentonite ◽  
High Level Radioactive Waste ◽  
Buffer Material ◽  
High Level ◽  
Crucial Parameter

In China, Gaomiaozi (GMZ) bentonite serves as a feasible buffer material in the high-level radioactive waste (HLW) repository, while its thermal conductivity is seen as a crucial parameter for the safety running of the HLW disposal. Due to the tremendous amount of heat released by such waste, the thermal conductivity of the buffer material is a crucial parameter for the safety running of the high-level radioactive waste disposal. For the purpose of improving its thermal conductivity, this research used the graphene oxide (GO) to modify the pure bentonite and then the nanocarbon-based bentonite (GO-GMZ) was obtained chemically. The thermal conductivity of this modified soil has been measured and investigated under various conditions in this study: the GO content, dry density, and water content. Researches confirm that the thermal conductivity of the modified bentonite is codetermined by the three conditions mentioned above, namely, the value of GO content, dry density, and water content. Besides, the study proposes an improved geometric mean model based on the special condition to predict the thermal conductivity of the compacted specimen; moreover, the calculated values are also compared with the experimental data.

Desiccation sensitivity and activities of free radical-scavenging enzymes in recalcitrant Theobroma cacao seeds

1999 ◽  
Vol 9 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Changrun Li ◽  
Wendell Q. Sun
Keyword(s):  
Lipid Peroxidation ◽  
Superoxide Dismutase ◽  
Water Content ◽  
Theobroma Cacao ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Desiccation Sensitivity ◽  
Critical Water Content ◽  
Scavenging Enzymes ◽  
Water Contents

AbstractMature and immature axes of Theobroma cacao (cocoa) seeds tolerated desiccation under a rapid-drying regime to critical water contents of 1.0 and 1.7 g g-1 dw, respectively. These critical water contents corresponded to water contents below which activities of free radical-scavenging enzymes (ascorbate peroxidase, peroxidase and superoxide dismutase) decreased rapidly during desiccation. The decline in axis viability below the critical water content was correlated with sharp increases in lipid peroxidation and cellular leakage. Cotyledon tissues were more desiccation-tolerant than axes, with a low critical water content of 0.24 g g–1dw. Desiccation sensitivity in cotyledon tissues was also correlated with the decrease in superoxide dismutase activity and increased lipid peroxidation products. However, in the cotyledons, no ascorbate peroxidase activity was detected at any water content, and peroxidase activity was gradually reduced as desiccation proceeded. Cocoa embryonic axes contained large amounts of sucrose, raffinose and stachyose but only traces of reducing monosaccharides. Desiccation sensitivity of recalcitrant cocoa axes did not appear to be due to the lack of sugar-related protective mechanisms during desiccation, and it was more likely related to the decrease of enzymic protection against desiccation-induced oxidative stresses.

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