scholarly journals Study of density and void ratio relation for reconstituted tropical residual soil at varying fines contents

2021 ◽  
Vol 40 (3) ◽  
pp. 371-378
Author(s):  
J.O. Okovido ◽  
E.O. Obroku
Keyword(s):  
Soil Mass ◽  
Coarse Sand ◽  
Degree Of Saturation ◽  
Dry Density ◽  
Residual Soil ◽  
Compression Tests ◽  
Residual Soils ◽  
Fines Content ◽  
Moisture Contents ◽  
Soil Behaviour

Soil behaviour may be hinged on the relative composition and nature of arrangement of the various component fractions embedded in the soil. Whether the component proportions of the fines (silt/clay) are interwoven within the voids of coarse (sand) grains, or that the coarse grains are dispersed within the fines mass would determine sandy or clayey soils characteristics. Density and voids ratio assessments of tropical residual soils were conducted in this study on compacted reconstituted binary blends of fines and coarse soils which were also subjected to cycles of sustained compression loads. The soil was separated into fines and coarse fractions by sieving through a 75μm sieve. Reconstituted soil samples were prepared from these two fractions in varying percentages ranging from zero fines content (0:100) to 100 percent fines fraction (100:0) in 10 percent increment. The results indicate that the moisture contents and changes in density due to moisture movements were insignificant for fines less than 40 percent. Compacted density and voids ratios were optimally maximum and minimum with values of about 2000kg/m3(dry density) and 0.2 respectively at fines contents of 20 percent. An optimal degree of saturation was also obtained at 20 percent fines. Optimum moisture contents were also obtained at about 30 percent with the corresponding optimum dry densities ranging from 2100kg/m3 to 2200kg/m3 from compression tests. The thresholds fines content therefore would depend on the stress state of the soil and may be about 20 or 30 percent for subgrade assessments or geotechnical considerations respectively and beyond the threshold fines content the fines fraction makes up the stress-carrying matrix for the soil mass thus controlling the soil behaviour.

scholarly journals A Simple Thermal Conductivity Model for Unsaturated Geomaterials Accounting for Degree of Saturation and Dry Density

2020 ◽  
Vol 6 (4) ◽  
Author(s):  
Agostino Walter Bruno ◽  
Doaa Alamoudi
Keyword(s):  
Thermal Conductivity ◽  
Coarse Sand ◽  
Degree Of Saturation ◽  
Dry Density ◽  
Conductivity Model ◽  
Thermal Conductivity Model ◽  
Dry Conditions ◽  
Density Factor ◽  
Materials Used ◽  
Different Levels

AbstractThis paper proposes a simple thermal conductivity model for geomaterials accounting for the combined effect of both degrees of saturation and dry density. The model only requires the determination of the thermal conductivity under dry conditions (i.e., at a degree of saturation equal to zero) and as little as two additional measurements of thermal conductivity performed at different levels of degree of saturation and dry density. The model is a function of only two fitting parameters, namely the moisture factor $${m}_{f}$$ m f and the density factor $${m}_{d}$$ m d . Despite its simplicity, the model can correctly predict the thermal conductivity of geomaterials and this has been validated against five sets of experimental data obtained on a very broad range of materials ranging from fine (e.g., bentonite) to coarser soils (e.g., a mix of gravel, coarse sand and silt) tested at different levels of degree of saturation and dry density. The paper also shows that the model can be applied to different engineering contexts such as (a) the thermal behaviour of earth materials used for building construction, (b) the thermal performance of bentonites employed for the storage of nuclear waste and (c) the estimation of the heat exchange in shallow geothermal reservoirs. Finally, the proposed model can be easily implemented in a finite element code to perform numerical simulations to study the heat transfer in unsaturated geomaterials.

scholarly journals Efficacy of Class C Fly Ash as a Stabilizer for Marginal Residual Soil

2020 ◽  
Vol 5 (1) ◽  
pp. 97-104
Author(s):  
M Umar ◽  
H. M. Alhassan
Keyword(s):  
Fly Ash ◽  
Road Construction ◽  
Strength Properties ◽  
Ash Content ◽  
Engineering Properties ◽  
Dry Density ◽  
Residual Soil ◽  
Compression Tests ◽  
Two Samples ◽  
Class C

Two laterites samples known for their deficiency in road construction were used to assess the efficacy of Class C fly ash in improving their engineering properties. The two samples were taken from Danbare and Dausayi localities within Kano Metropolis and the fly ash was sourced from the Nigerian Coal Corporation, Enugu. Preliminary tests on the two samples confirmed their deficiency for use in road construction. The processed fly ash was blended with the laterite samples at 0, 3, 6, 9, 12, 15 and 18%. Hence, the treated soil samples were tested for plasticity, compaction and strength properties. Results obtained revealed reduction in plasticity properties as the fly ash contents increased. Similarly, Maximum Dry Density (MDD) decreased as the fly ash content increased while the Optimum Moisture Content (OMC) of the treated soils increased for the two samples. Peak CBR values of 16 and 35% were obtained at 9 and 15% fly ash contents for samples 1 and 2, respectively. The unconfined compression tests showed considerable improvement in strength properties higher than the values of the natural soils. The peak 7 days strength of 630 and 1410 kN/m2 were observed at 12% and 15% fly ash content for samples 1 and 2, respectively.

Undrained Behavior of Unsaturated Bentonite-Sand Mixture

2012 ◽  
Vol 446-449 ◽  
pp. 1454-1457
Author(s):  
Wen Jing Sun ◽  
De An Sun ◽  
Jin Yi Zhang
Keyword(s):  
Confining Pressure ◽  
Degree Of Saturation ◽  
Dry Density ◽  
Compression Tests ◽  
Shear Tests ◽  
Isotropic Compression ◽  
Sand Mixture ◽  
Mechanical Behaviours ◽  
Undrained Behavior ◽  
Gaomiaozi Bentonite

The strength, deformation and hydro-mechanical behaviours of a compacted unsaturated Gaomiaozi bentonite-sand mixture under undrained condition are studied by conducting a series of isotropic compression tests and triaxial shear tests under constant water content. During undrained isotropic compression testing, void ratio and suction decrease while degree of saturation increases. The stress-strain relations are obtained from undrained triaxial shear tests. The volume contraction and lateral expansion can be observed. The suction decreases with increasing shearing. The net confining pressure and initial dry density affect the initial rigidity, undrained shear strength, volumetric deformation and hydro-mechanical behaviour.

Influence of pressure, saturation, and temperature on the behaviour of unsaturated sand-bentonite

1998 ◽  
Vol 35 (2) ◽  
pp. 194-205 ◽  
Author(s):  
Bradley Wiebe ◽  
James Graham ◽  
Gary Xiangmin Tang ◽  
David Dixon
Keyword(s):  
Elevated Temperatures ◽  
Triaxial Compression ◽  
Saturation Pressure ◽  
Degree Of Saturation ◽  
Dry Density ◽  
Mean Stress ◽  
Compression Tests ◽  
Water Drainage ◽  
Open Drainage ◽  
Unsaturated Sand

Triaxial compression tests were performed on unsaturated sand-bentonite buffer at elevated temperatures and pressures. Air and water drainage lines from the specimen were generally kept closed through (i) heating, (ii) pressuring, and (iii) shearing. The tests can therefore be characterized as undrained-undrained-undrained tests. Effects of open drainage were also explored. Confining pressures ranged from 0.2 to 3.0 MPa at temperatures of 26, 65, and 100°C. Specimens were statically compacted to a constant dry density of 1.67 Mg/m3, and to degrees of saturation between 35 and 98%. Suction - water content relationships were established to determine the initial total suction before testing. Results indicate that undrained strengths increase with decreasing degree of saturation (50 <= Sr <= 100%), with increasing confining pressure, and with decreasing temperature. The normalized compression modulus E50/su does not respond monotonically to changes in saturation, pressure, and temperature. Changes in strength and stiffness have been described in relation to net mean stress and suction in shear strength - net mean stress - suction space.Key words: sand-bentonite, unsaturated, suctions, temperature, strength, stiffness, structure.

Experimental Study on Unconfined Compression Strength of Compacted Granite Residual Soils

2011 ◽  
Vol 250-253 ◽  
pp. 2124-2128
Author(s):  
Dong Xia Chen ◽  
Kai Yang ◽  
Yan Yang
Keyword(s):  
Moisture Content ◽  
Compression Strength ◽  
High Strength ◽  
Degree Of Saturation ◽  
Unconfined Compression Strength ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Residual Soils ◽  
Engineering Structures ◽  
Wetting And Drying

Granite residual soils are often used as compacted soils in engineering structures such as pavement, embankments and backfills in Xiamen. Many geotechnical problems such as bearing capacity, lateral earth pressures and slope stability require an assessment of the shear strength of soil. Since the geotechnical properties of residual soils are impaired in contact with water, a series of unconfined compression tests are carried out on granite residual soils. Results of tests include effects of degree of compaction, moisture content, degree of saturation and cyclic wetting and drying on unconfined compression strength respectively. The increase in degree of compaction and compacting effort increases unconfined compression strength and the former greatly affects the strength. Moisture content of soils is higher than the optimum one of 2.5% for high strength and it is lower than optimum one of 2.5% for good plasticity in Xiamen areas. The degree of saturation of high unconfined compression strength normally ranges from 64% to 76%. In addition, cyclic wetting and drying causes loss of unconfined compression strength and the maximum loss commonly occurs at the first cycle and then is slowed down by the following cycles till the strength remains approximately constant.

Quantitative Study for the Impact of Fines Content on Soil Surface Cracking

2012 ◽  
Vol 594-597 ◽  
pp. 140-147
Author(s):  
Yang Lu ◽  
Ning Sheng Chen ◽  
Li Qun Lv ◽  
Ming Feng Deng
Keyword(s):  
Surface Area ◽  
Soil Surface ◽  
Soil Mass ◽  
Total Surface Area ◽  
Dry Density ◽  
Surface Cracks ◽  
Fines Content ◽  
Surface Cracking ◽  
Small Cracks ◽  
Cracked Soil

Cracking development in soils is of significance for their physical and mechanical properties. The fines content in soils is one of the most important factors in cracking development, leading to it being of great importance to quantitatively study how the cracking development is influenced by the fines content. In this paper, experimental simulations on soil surface cracking were first conducted in the lab with soil from Jiangjia Valley. Digital image processing technology was then applied to investigate cracking in soil with different fines content by describing the surface cracks with crack area density Ac (ratio of all cracks’ area to total surface area of the cracked soil) and crack line density Lc (ratio of all cracks’ perimeters to total surface area of the cracked soil). The conclusions are drawn as follows: 1) Surface cracks increase with fines content going up; specifically, when the soil mass with fines content ranging from 20% to 30%, there is a significant increase in cracks; There is no crack developed in the soil with no fines, comparing to the gradual increase in soils with other fines content. 2) With the loss of water content, Ac and Lc will increase until a constant value is reached. However, small cracks will be closed and big ones will evolve into smaller ones if enough water is added. 3) Soil mass with fines content less than 20% is inclined to have small cracks when it is drying and cracks will be closed if enough water is added; on the other hand, soil mass with fines content more than 20% is inclined to have bigger cracks and they will become smaller when submerged into water. 4) After times of wetting and drying cycles, soil mass shrinks and soil dry density increases, which leads to the decrease of Dc and Lc, which suggests soil with larger dry density will probably have fewer cracks.

Research on Engineering Geology Properties of Residual Diorite in Jinan, Shandong Province, China

2012 ◽  
Vol 594-597 ◽  
pp. 434-438
Author(s):  
Min Shang ◽  
Qiang Xu ◽  
Shu Cai Li ◽  
Lan Xin Zhang
Keyword(s):  
Engineering Geology ◽  
Rock Type ◽  
Physical And Mechanical Properties ◽  
Soil Mass ◽  
Engineering Practice ◽  
Residual Soil ◽  
Residual Soils ◽  
Practice Experience ◽  
The Difference

Residual soils are weathering products of rocks that are commonly found under unsaturated conditions. Residual soil is one of special soils, and its engineering geology property is usually different because of the difference of resource rock type, the geology environment and weathering condition. By the means of analysis of the data attained by the methods of field exploration, laboratory test and testing in-situ, the physical and mechanical properties of the residual diorite in Jinan were studied deeply. It is proved that the stratigraphic section of the soil can be classified as two layers on the perpendicular direction. Considering the inhomogeneity of the residual soil mass and the widely divergence of the value of mechanics properties, the suggestion value of c, Φ , a, Es, fak were put forward for further guiding the engineering practice , on the base of physics and mechanics properties tests and the region practice experience. At the same time, it is pointed out that, at that region, the interlayer and inhomogeneity of the weathering layers should be emphasized in the process of projecting and constructing when the residual diorite acts as the foundation of the construction or one of the geologic layers.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

Macrostructural and Microstructural Properties of Residual Soils as Engineered Landfill Liner Materials

2021 ◽  
Author(s):  
Lee Li Yong ◽  
Vivi Anggraini ◽  
Mavinakere Eshwaraiah Raghunandan ◽  
Mohd. Raihan Taha
Keyword(s):  
Tap Water ◽  
Chemical Precipitation ◽  
Soil Samples ◽  
Residual Soil ◽  
Diffuse Double Layer ◽  
Microstructural Properties ◽  
Residual Soils ◽  
Soil Leachate ◽  
Landfill Liner ◽  
X Ray

ABSTRACT This study assessed the performance of residual soils with regard to their macrostructural and microstructural properties and compatibility with leachate in pursuit of exploring alternative cost-effective and efficient landfill liner materials. A series of laboratory investigations was conducted on three residual soil samples by using tap water and leachate as permeation fluid to achieve the objectives of the study. The zeta potential measurements revealed that the presence of multivalent cations in the leachate decreased the diffuse double layer (DDL) thickness around the soil particles. The reduced DDL thickness caused a decrease in Atterberg limits of soil-leachate samples and changes in the classification of fine fractions. Additionally, the effects of pore clogging attributed to chemical precipitation and bioclogging were responsible for the reduction in measured hydraulic conductivities of soil-leachate samples. These effects can be clearly observed from the field-emission scanning electron microscopy images of soil-leachate samples with the appearance of less visible voids that led to a more compact and dense structure. The formation of new non-clay minerals and associated changes in the Al and Si ratio as reflected in the x-ray diffraction diffractograms and energy-dispersive x-ray analyses, respectively, were attributed to the effects of chemical precipitation. This study concluded that S1 and S2 residual soil samples are potential landfill liner materials because they possess adequate grading characteristics, adequate unconfined compressive strength, low hydraulic conductivity, and good compatibility with leachate. In contrast, the S3 sample requires further treatment to enhance its properties in order to comply with the requirements of landfill liner materials.

Small strain stiffness for granite residual soil: effect of stress ratio

2021 ◽  
Author(s):  
Xianwei Zhang ◽  
Xinyu Liu ◽  
Lingwei Kong ◽  
Gang Wang ◽  
Cheng Chen
Keyword(s):  
Stress Ratio ◽  
Small Strain ◽  
Residual Soil ◽  
Resonant Column ◽  
Residual Soils ◽  
Column Tests ◽  
Small Strain Stiffness ◽  
Deviator Stress ◽  
Granite Residual Soil ◽  
Stress Ratios

Most previous studies have focused on the small strain stiffness of sedimentary soil while little attention has been given to residual soils with different properties. Most studies also neglected the effects of the deviator stress, which is extensively involved in civil engineering. This note considers the effects of the deviator stress on the small-strain stiffness of natural granite residual soil (GRS) as established from resonant column tests performed under various stress ratios. Although increasing the stress ratio results in a greater maximum shear modulus for both natural and remolded residual soils, remolded soil is more sensitive to changes in the stress ratio, which highlights the effects of soil cementation. The data herein offers new insights to understand the stiffness of residual soil and other weathered geomaterials.

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