Study on Libyan Silt Property and Suggestions on its Application in Subgrade Construction

2014 ◽  
Vol 587-589 ◽  
pp. 1305-1310
Author(s):  
Ze Yu Zhang ◽  
Li Yun Peng ◽  
Jian Ye Wang ◽  
Abobakir Abdulali
Keyword(s):  
Mechanical Properties ◽  
Direct Shear Test ◽  
Shear Test ◽  
Physical And Mechanical Properties ◽  
Soil Improvement ◽  
Liquid Limit ◽  
Direct Shear ◽  
Test Results ◽  
Soil Slope ◽  
Capillary Water

The basic physical and mechanical properties of Libyan soil are analyzed through some experiments, including direct shear test, grading analysis test and compression test. According to the test results, the soil is named as low liquid limit silt featured by weak strength, high compressibility and permeability, which directly influences sub-grade stability, durability and pavement’s usability. In order to solve these problems, measures are discussed from two aspects, namely, soil improvement and construction method. The strength of the soil is apparently increased by the cement and lime adding, and the compressibility is decreased at the same time. And the rising height of capillary water reducing and protection forms for silt soil slope are also proved to be effective in the subgrade construction.

The Research on the Mechanical Properties of the same Curing Agent of Different Soil Dredged Mud

2013 ◽  
Vol 800 ◽  
pp. 181-188
Author(s):  
Xiao Yan Yang ◽  
Wen Bai Liu ◽  
Jia Jun Wang ◽  
Wen Hui Shi
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Compression Test ◽  
Direct Shear Test ◽  
Shear Test ◽  
Silty Sand ◽  
Curing Agent ◽  
Direct Shear ◽  
Confined Compression ◽  
Silty Soil

Through confined compression test and direct shear test, studied the mechanical properties of the same curing agent of different soil dredged mud, compared the difference of the same curing agent of different soil dredged mud. By confined compression test, the compression modulus of clay, silty sand and silty soil dredged mud after curing increases by 603.7%, 529.0% , 603.7% respectively. By direct shear test, the shear strength of clay dredged mud after curing increases to infinity; silty sands shear strength after curing increases by 209.1% in average; silty soils shear strength increases after curing by 147.5% in average. The compression and shear resistance of this kind of special curing agent for clay is best, silty sand second, but for the silty soil only has a little effect.

scholarly journals Study on the Mechanical Properties of Red Clay under Drying-Wetting Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Qi Yanli ◽  
MingZhou Bai ◽  
Hao Zhou ◽  
Hai Shi ◽  
Pengxiang Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Direct Shear Test ◽  
Shear Test ◽  
Strain Curve ◽  
Stress And Strain ◽  
Direct Shear ◽  
Guangxi Province ◽  
Red Clay ◽  
Plastic Hardening ◽  
The Relationship

To study the mechanical properties of red clay under repeated dry and wet cycle test conditions, in this paper, the disturbed red clay in an engineering area in Liuzhou, Guangxi Province, was taken as the research object. By artificially controlling different dry and wet cycles in the laboratory, a direct shear test and triaxial consolidation drainage test were carried out on the red clay samples after different dry and wet cycles. The stress-strain curve and change rule of corresponding c and φ values were obtained. The results showed that, in both the direct shear test and the triaxial test, the shear strength parameters of red clay decreased with an increase in the number of dry and wet cycles and the attenuation was most obvious during the first cycle. With an increase in the number of dry and wet cycles, the attenuation gradually decreased. The constitutive model of the deviatoric stress and strain curve of red clay under dry and wet cycles was a plastic-hardening type. By analyzing the variation in parameters in the P-H model, the relationship between c, φ, and the number of dry and wet cycles n was obtained. The results showed that the parameters had different degrees of attenuation with the action of dry and wet cycles. To explain the above rules, some samples under different drying-wetting cycles were selected for environmental electron microscope scanning, and appropriate assumptions were made based on the microstructure.

Effect of weathering on the compressibility and shear strength of a natural clay

2006 ◽  
Vol 43 (6) ◽  
pp. 618-625 ◽  
Author(s):  
Giovanni Gullà ◽  
Maria Clorinda Mandaglio ◽  
Nicola Moraci
Keyword(s):  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Direct Shear ◽  
Test Results ◽  
Natural Clay ◽  
Standard Equipment ◽  
Overconsolidated Clays ◽  
Weathering Process

In situ, seasonal changes expose soils to frequent wetting–drying–freezing–thawing cycles. Such processes can favour and trigger shallow instabilities controlled by the weathering process. This paper presents an experimental study carried out to investigate the effects of the weathering process, caused by the wetting–drying–freezing–thawing cycles, on the compressibility and shear strength of a natural clay. Several specimens were trimmed from block samples of overconsolidated clays taken from a slope in south Calabria, Italy. Specimens were subjected to wetting–drying–freezing–thawing cycles of different durations and then tested with standard equipment (oedometer and direct shear). Test results show that the wetting–drying–freezing–thawing cycles caused a change in the initial microstructure that produced a decrease in the compression index and an increase in the swelling index. Moreover, the direct shear test results show a decrease in the peak shear strength and demonstrate that a larger reduction occurs in the first month of weathering cycles. The intense cycles performed in the laboratory produced a decay of compressibility and a shear strength approaching reconstituted values. The conclusions are important when choosing the shear strength parameters required when studying shallow landsliding in clay slopes.Key words: weathered clay, structure, cycle of degradation, shallow instability.

scholarly journals Comparative Study in Method of Compaction by Consolidated Drained and Direct Shear Test

2020 ◽  
Vol 78 (2) ◽  
pp. 143-152
Author(s):  
Abdul Samad Abdul Rahman ◽  
N. Sidek ◽  
Juhaizad Ahmad ◽  
N. Hamzah ◽  
M. I. F. Rosli
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Triaxial Test ◽  
Direct Shear Test ◽  
Shear Test ◽  
Void Ratio ◽  
Direct Shear ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behaviour

Soil compaction has been a common practice in the construction of highways, embankments, earth dams and other related structures where the condition of the soil is high in void ratio and therefore having a very low in bearing capacity. Therefore, the soil needs to be compacted in order to minimize the void ratio and in the same time would results in having a very high bearing capacity to sustain load. Nevertheless, only a few researches have been done to investigate the method of compaction using different energy on the behavior of shear strength by consolidated drained and direct shear test. In this research, the effect of different compaction in energy of 25 number of blows compared to 40 number of blows on the stress-strain behaviour of drained triaxial test has been done and findings of the data are to be compared with direct shear test. Results reveal that there is an increase in soil unit weight by using different energy in compaction with an increase of 5% from 1790 kg/m3 to 1880 kg/m3 for 25 and 40 number of blows respectively. However, the stress-strain behaviour of the specimens shows differently when compared between consolidated drained triaxial and direct shear test. The shear strength for direct shear-stress is at higher value compared to drained triaxial test. For drained triaxial test, results reveal that the effective friction angles are increase only about 1% from 37° to 38°. This is due to the soil particles rearranging itself with the different applied pressures thus eliminating the effects of different energy on the shear strength of the specimens. However, for direct shear test, the shear strength increases drastically from 29° to 32°. The increase of the shear strength is more likely influence by the soil particle arrangement due to the impact of the energy of the no of blows to the desired specimen.

scholarly journals Study on Spatial Variation of Shear Mechanical Properties of Soil-rock Mixture

2019 ◽  
Author(s):  
Yanhai Wang ◽  
Jianlin Li ◽  
Qiao Jiang ◽  
Yisheng Huang ◽  
Xinzhe Li
Keyword(s):  
Mechanical Properties ◽  
Spatial Variability ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Three Gorges Reservoir Area ◽  
Direct Shear ◽  
Transverse Slope ◽  
Slope Direction

The soil-rock mixture (SRM) is a kind of special engineering geological material, which has been exposed to the field for a long time and is affected by rainwater seepage, geological force, slope sliding force and human activities, resulting in the spatial variability of its mechanical properties. Taking the SRM distributed on a slope of the Three Gorges Reservoir area as the research object, four test locations were selected along and transverse the slope. First, in-situ large-scale direct shear test was carried out, and then the laboratory large-scale direct shear test, particle sieving test, and water content test were carried out in the undisturbed sample to study the variation of shear mechanical properties of SRM distributed in different spatial locations. The results show that: (1) Under the same normal stress, the peak strength of the SRM decreases at a similar rate along the slope direction and the transverse slope direction. (2) The cohesion of the SRM is continuously strengthened, and the friction angle is continuously deteriorated along the slope from high to low, the cohesion and friction angle are almost no variability along the transverse slope. (3) The mechanism of the above-mentioned variation in the shear mechanics parameters of SRM is that the lower the elevation along the slope, the more fragmented the rock, the lower the rock content. (4) Spatial variability models of cohesion and friction angle of SRM were established, which can provide references for related engineering applications.

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