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

Study on the Clay Mechanical Characteristics of “Ripping Up the Bottom” in the Yellow River

2012 ◽  
Vol 212-213 ◽  
pp. 108-112 ◽  
Author(s):  
Wen Sheng Dong ◽  
Xiu Fang Jiang ◽  
Xian Feng He ◽  
Ying Ying Zai
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Mechanical Strength ◽  
Water Content ◽  
Critical Condition ◽  
Mechanical Characteristics ◽  
Yellow River ◽  
The Yellow River ◽  
Dry Density ◽  
The Relationship

Aim to the high sandy river “ripping up the riverbed” phenomenon, by experiment, analyzing the relationship between clay dry density, water content, plasticity index and its shear strength, and its mechanical properties. Create the conditions for studying clay mechanical strength and the critical condition of “bottom tearing scour”.

Influences of Change of Plasma on CBR of Eolian Sand

2011 ◽  
Vol 250-253 ◽  
pp. 3120-3127 ◽  
Author(s):  
Chang Ning Jin ◽  
Yu Hong Zhang
Keyword(s):  
Water Content ◽  
Clay Particle ◽  
Dry Density ◽  
Mechanism Analysis ◽  
Particle Content ◽  
Clay Particles ◽  
Eolian Sand ◽  
Cbr Test ◽  
Saturated Water Content ◽  
Test Result

The plasma in the eolian sand, included silt particle and clay particle, change easily and hugely. For studying their influences on the strength property of eolian sand, mixed silt particles and clay particles in different proportion into the eolian sand to carry out CBR test. The test result indicates that, along with the increase of silt particle and clay particle content the CBR value also increases within a certain range, which indicates the increase of silt particle and clay particle content can firstly improve the gradation of eolian sand; after the gradation is improved can obtain large compaction dry density, and at the same time also can enhance the earth strength, included the CBR value. The range of silt particle and clay particle content made the CBR value increase is also very large: ≤40% when formed under dry state, and ≤45% when formed under optimum or saturated water content; if the water content in forming could be retained at all times, the former could be ≤55% and the latter still ≤45%. The mechanism analysis further indicates that, when there were no excessive silt particles and clay particles, in the large range of silt particles and clay particles changing from small to large, the engineering nature of eolian sand will be improved due to the improvement of gradation, which is advantageous to the extensive application of dry compaction process; but the eolian sand formed by dry compaction is defective on microstructure, and so the requirements for silt particle and clay particle content should be more strict in practical works.

scholarly journals Analisis Sandcone Test (AASHTO T 191 dan ASTM D 1556 64) Pada Peningkatan Jalan Jepara – Kedungmalang – Pecangaan

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Yayan Adi Saputro ◽  
Khotibul Umam ◽  
Shiska Fauziah
Keyword(s):  
Water Content ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
Building Structure ◽  
The Road ◽  
Central Java ◽  
Maximum Water ◽  
The Difference ◽  
Test Result ◽  
Maximum Water Content

Concrete road works on the improvement of the Jepara - Kedungmalang - Pecangaan road are the activities of the Publick Works Department of Highways in Central Java Province. Quality control in a building structure work is very important to support the strength of the structure. In planning the road structure, it is necessary to have density of soil and foundation layers that meet the requirements. To get the value of the degree of density that is from the sandcone test where in the sandcone test there are several standart methods or references for example from AASHTO T 191 and ASTM D 1556 - 64. In this study the aims is to obtain the value of the degree of density, how big is the difference between the AASHTO T 191 standart and ASTM D 1556 - 64, and know the water content. From the test result, the optimum moisture content value is 6.5%, dry density is 2.17gr/cm3, the value of the degree of density mostly ranges from ">100%, and the minimum water content value is 5.00% maximum water content is 6.7%.

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.

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.

scholarly journals Experimental Study on Main Physical Parameters Controlling Shear Strength of Unsaturated Loess

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Wen-tong Tian ◽  
Jian-hua Dong ◽  
Jun-jie Sun ◽  
Bo Yang
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Quartz Sand ◽  
Clay Content ◽  
Friction Angle ◽  
Dry Density ◽  
Physical Parameters ◽  
Sandy Silt ◽  
Unsaturated Loess

It is particularly important to study the strength of unsaturated loess, and its accurate determination is crucial to the stability analysis of soil slope and foundation and calculation of earth pressure. In order to reveal the control mechanism of physical parameters on the shear strength of unsaturated loess, the intact and remolded loess were used as the research object; sandy silt, quartz flour, and quartz sand were used as contrast; the systematic direct shear tests of unsaturated loess, sandy silt, and quartz sand under different conditions of water content, dry density, and clay content were carried out. The results show that the cohesion, internal friction angle, and shear strength of unsaturated loess piecewise functionally decrease with the increase of water content, its shear strength increases linearly with the increase of dry density, and its internal friction angle shows an upward quadratic function relation with the increase of clay content. The law results of comparing sandy silt, quartz flour, and quartz sand with loess considering water content and dry density are the same; therefore, the equation of shear strength of unsaturated loess is proposed for practical engineering reference, and by the first derivative analysis of the equation, it is feasible to determine the control proportion of the three parameters on the shear strength of unsaturated loess. A stage-like difference between the three control proportions is observed, depending on the combination variations of water content and clay content.

scholarly journals Effect of clay content on strength and permeability of plastic loess-cement

2019 ◽  
Vol 48 (2) ◽  
pp. 25-30
Author(s):  
Boriana Tchakalova
Keyword(s):  
Water Content ◽  
Soil Stabilization ◽  
Clay Fraction ◽  
Clay Content ◽  
Loess Soil ◽  
Liquid Limit ◽  
Engineering Properties ◽  
Natural Soil ◽  
Dry Density ◽  
Maximum Dry Density

Plastic soil-cement is a type of soil stabilization used for the treatment of natural soil to improve its engineering properties. It is a hardened material prepared by mixing soil and Portland cement at a water content higher than optimum, usually near the liquid limit, without compaction at optimum water content to maximum dry density. In Bulgaria, this soil stabilization technique has been applied in foundation works in collapsible loess ground in order to replace a part of the collapsible layer, to increase the bearing capacity of the soil base and/or to isolate the geoenvironment from migration of pollutants. The aim of the current paper is to examine the effect of the clay content of the loess soil on the strength and permeability of plastic loess-cement. Results from the investigation indicate that the mechanical and hydraulic properties of the plastic loess-cement highly depend on the presence of clay fraction.

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.

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