A Comparative Study of Hydromechanical Properties in Saturated and Partially Saturated Conditions of Two Soils from the Runway of Oran Airport

2017 ◽  
Vol 21 ◽  
pp. 319-326
Author(s):  
Mohamed Chikhaoui ◽  
Dashnor Hoxha ◽  
Naima Belayachi ◽  
Ammar Nechnech
Keyword(s):  
Triaxial Compression ◽  
Confining Pressure ◽  
Natural Soil ◽  
Compression Tests ◽  
Partially Saturated ◽  
Laboratory Results ◽  
Pressure Meter ◽  
Statistical Representativeness ◽  
Triaxial Compression Tests

This study concerns the ground soils of the second runway of the Es-Sénia airport in Oran (Algeria). This airport was built on a very complex hydro geotechnical site when underground cavities, following the dissolution of gypsum soil, were found during the before-construction geologic studies. Several, techniques are used in laboratory (Permeability, triaxial compression tests at various confining pressure, and hydric tests in saturated and unsaturated conditions) and for in situ it’s used the results of SPT and pressure-meter tests. A comparison of parameters of two soils identified in saturated and partially saturated conditions by in situ and laboratory tests was performed in order to respond to questions of the similarity of hydro mechanical properties of two soils as well as their statistical representativeness of the in-situ reality. It is found that, in respect to the studied parameters, laboratory results are statistically significant and reconstituted soils is statistically representative of natural soil reconstitution.

scholarly journals Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1943
Author(s):  
Fu Yi ◽  
Changbo Du
Keyword(s):  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Strength Index ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Zhang Model ◽  
Triaxial Compression Tests

To evaluate the shear properties of geotextile-reinforced tailings, triaxial compression tests were performed on geogrids and geotextiles with zero, one, two, and four reinforced layers. The stress–strain characteristics and reinforcement effects of the reinforced tailings with different layers were analyzed. According to the test results, the geogrid stress–strain curves show hardening characteristics, whereas the geotextile stress–strain curves have strain-softening properties. With more reinforced layers, the hardening or softening characteristics become more prominent. We demonstrate that the stress–strain curves of geogrids and geotextile reinforced tailings under different reinforced layers can be fitted by the Duncan–Zhang model, which indicates that the pseudo-cohesion of shear strength index increases linearly whereas the friction angle remains primarily unchanged with the increase in reinforced layers. In addition, we observed that, although the strength of the reinforced tailings increases substantially, the reinforcement effect is more significant at a low confining pressure than at a high confining pressure. On the contrary, the triaxial specimen strength decreases with the increase in the number of reinforced layers. Our findings can provide valuable input toward the design and application of reinforced engineering.

scholarly journals The mechanics of subglacial sediment: an example of new “transitional” behaviour

2010 ◽  
Vol 47 (7) ◽  
pp. 775-790 ◽  
Author(s):  
Fatin Altuhafi ◽  
Béatrice A. Baudet ◽  
Peter Sammonds
Keyword(s):  
Critical State ◽  
Triaxial Compression ◽  
Interesting Case ◽  
Strain History ◽  
Compression Tests ◽  
Specimen Density ◽  
The Difference ◽  
Triaxial Compression Tests ◽  
Normal Compression

A series of isotropic compression tests and drained and undrained triaxial compression tests have been performed on glacial sediment from Iceland. Langjökull sediment, which is well graded, is thought to have reached a critical grading during deposition and transportation. Multiple parallel normal compression lines (NCLs) were found, but a unique critical state line (CSL) could be identified. This is unlike other so-called “transitional” soils, whose grading varies between reasonably well graded to gap graded, which tend to have distinct NCLs and critical state lines depending on the specimen density. It is thought that in the case of the Langjökull sediment studied, its particular strain history that involved incessant shearing during deposition accounts for the difference in behaviour. This provides the interesting case of a soil that has been crushed to a critical grading in situ, which depends on the mineralogy of the grains, which was then sampled and tested. Despite the unique grading, samples with a range of different void ratios can be prepared and the combination of grading and density seems to set a fabric that cannot be changed by compression, resulting in multiple parallel NCLs. At the critical state, however, the fabric has been destroyed and the CSL is unique.

Mechanical Properties of Bentonite-Sand Mixtures Under Triaxial Stress Condition

1994 ◽  
Vol 353 ◽  
Author(s):  
M. Umedera ◽  
A. Fujiwara ◽  
N. Yasufuku ◽  
M. Hyodo ◽  
H. Murata
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Water Content ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Strength Properties ◽  
Compression Tests ◽  
Optimum Water Content ◽  
Triaxial Compression Tests ◽  
Optimum Water

AbstractA series of triaxial compression tests is being conducted under the drained condition on bentonite and sand mixtures, known as buffer, in saturated and optimum water content states to clarify the mechanical properties of the buffer.It was found that the mechanical properties of bentonite and sand mixtures are strongly influenced by water and bentonite contents: shear strength in a saturated state is less than that in an optimum water content state; shear strength decreases rapidly with increasing bentonite content. Strength properties are much dependent on confining pressure.

Experimental Study of Stress-Strain Characteristics of the Fly Ash Blended with Curing Agent

2010 ◽  
Vol 168-170 ◽  
pp. 1934-1942
Author(s):  
Zheng Shen ◽  
Lan Zong ◽  
Xiang Dong
Keyword(s):  
Fly Ash ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Uniaxial Stress ◽  
Curing Agent ◽  
Compression Tests ◽  
Growth Trend ◽  
Stress Strain ◽  
Confining Pressures ◽  
Triaxial Compression Tests

The stress-strain characteristics of the fly ash blended with curing agent was studied using uniaxial and triaxial compression tests. Curing agent JNS-2 was used as the stabilizing agents in sample preparation. Four curing agent JNS-2 contents of 3%, 6%, 9% and 12% were selected for sample preparation. UU triaxial compression tests were conducted in a range of confining pressures from 100 kPa to 300 kPa. The experimental results obtained from the laboratory tests showed that curing age, mixture ratio, compaction degree and confining pressures had significant influence on the shape of curves. Uniaxial stress-strain test results demonstrated that the latter strength and deformation characteristics of the fly ash blended with curing agent grew little and with the increase of curing agent amount and compaction factor, the curve of uniaxial stress-strain changed significantly. On the other hand, triaxial stress-strain test results indicted that the failure strain showed a partial negative growth trend with the increase of curing agent amount, and the failure stress showed a partial positive growth trend with the increase of curing agent amount. When the curve was at high confining pressure, it showed hardening type, when at low confining pressure it showed softening type.

scholarly journals Assessment of strength and deformation of lightweight concrete and its components under triaxial compression, taking into account the macrostructure of the material

2021 ◽  
Vol 264 ◽  
pp. 02015
Author(s):  
Chorikul Raupov ◽  
Ulugbek Shermuxamedov ◽  
Anora Karimova
Keyword(s):  
Lightweight Concrete ◽  
Triaxial Compression ◽  
Experimental Studies ◽  
Confining Pressure ◽  
Hardened Cement ◽  
Compression Tests ◽  
Triaxial Strength ◽  
Pressure Parameter ◽  
Strength And Deformation ◽  
Triaxial Compression Tests

The paper presents the results of experimental studies on the strength and deformations of lightweight concrete, mortar matrix and hardened cement paste under triaxial compression. Tests on samples were carried out using short-term triaxial proportional σ1 > σ2 = σ3 loading (i.e. axial compression + lateral hydrostatic pressure). During the loading, the ratio of the main stresses (both axial and lateral) was kept constant up to the end of tests. The experimental studies were carried out for different low ratios of σ2/σ1. A theoretical estimation has been discussed to approximate experimental results and prediction of triaxial strength values for different types of lightweight concrete. An estimation of the confining pressure parameter K has been done for the used mode of loading.

Analysis on Bolt Supporting Mechanism for Roadways Driving along next Goaf Based on Triaxial Compression Test

2012 ◽  
Vol 594-597 ◽  
pp. 1159-1162
Author(s):  
Sheng Zhong ◽  
Yong Jie Yang ◽  
Min Wang
Keyword(s):  
Mechanical Test ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test System ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Conventional Triaxial Compression ◽  
Strength And Deformation ◽  
Rock Mechanical Test ◽  
Triaxial Compression Tests

Conventional triaxial compression tests of coal specimens are carried out by MTS815 servo-controlled rock mechanical test system, and the strength and deformation characteristics of coal under different confining pressure are analyzed. On that basis, bolt supporting mechanism of surrounding rocks of roadways driving along next goaf is studied.

An Elastoplastic Model for Granular Materials Exhibiting Particle Crushing

2007 ◽  
Vol 340-341 ◽  
pp. 1273-1278 ◽  
Author(s):  
De An Sun ◽  
Wen Xiong Huang ◽  
Dai Chao Sheng ◽  
Haruyuki Yamamoto
Keyword(s):  
Shear Strength ◽  
Granular Materials ◽  
Triaxial Compression ◽  
Model Performance ◽  
Confining Pressure ◽  
Model Parameters ◽  
Compression Tests ◽  
Particle Crushing ◽  
Wide Range ◽  
Triaxial Compression Tests

A practical elastoplastic constitutive model for granular materials is presented. And the model is suitable for description of the material behaviour for a wide range of stresses, including those sufficient to cause particle crushing. With a limited number of model parameters, the model can predict the confining-pressure dependent stress-strain relation and shear strength of granular materials in three-dimensional stresses, especially of variation of shear strength and dilatancy characteristics due to particle crushing under high confining pressure. The model parameters, which have clear physical meanings, can be determined from the results of isotropic compression test and conventional triaxial compression tests. The model performance is demonstrated for triaxial compression tests of a sand for a wide range of the confining-pressure from 0.2MPa to 8.0MPa.

Mechanical Properties of Sandstone under Loading and Unloading Conditions

2014 ◽  
Vol 852 ◽  
pp. 441-446 ◽  
Author(s):  
Xing Xia Wang ◽  
Wen Juan Ma ◽  
Jian Wen Huang ◽  
Zai Yi Liao
Keyword(s):  
Mechanical Properties ◽  
Triaxial Compression ◽  
Deformation Modulus ◽  
Confining Pressure ◽  
Rock Deformation ◽  
Test Results ◽  
Compression Tests ◽  
Triaxial Compressive Strength ◽  
Unloading Confining Pressure ◽  
Triaxial Compression Tests

The mechanical properties of rock mass under unloading conditions are essentially different from that under loading conditions. Triaxial compression tests and unloading confining pressure tests are conducted, and test results show that unloading failure is more brittle, and rock samples suffer more damage under unloading failure. The larger the initial confining pressure is, the easier of unloading failure is occurred. The increasing or decreasing values of rock deformation modulus under unloading conditions are within 10% of rock triaxial compressive strength. Unloading failure leads to deterioration of rock deformation modulus, which decreases gradually with confining pressure decreasing, and the decrease rates get bigger and bigger with unloading ratio of confining pressure increasing. Deformation modulus is only 24-34% of that under loading condition when rock strength goes down to residual strength.

scholarly journals Experimental Investigation on the Deformation, Strength, and Acoustic Emission Characteristics of Sandstone under True Triaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Zhaolin Li ◽  
Lianguo Wang ◽  
Yinlong Lu ◽  
Wenshuai Li ◽  
Kai Wang
Keyword(s):  
Acoustic Emission ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Lateral Strain ◽  
Compression Tests ◽  
True Triaxial ◽  
Shear Slip ◽  
True Triaxial Compression ◽  
Triaxial Compression Tests

The study of deformation, strength, and other mechanical characteristics of sandstone under true triaxial compression is significant for understanding failure mechanisms in rock and evaluating the stability of underground structures. Conventional and true triaxial compression tests for sandstone are conducted for different stress states in this study using the self-developed true triaxial electrohydraulic servo test system combined with acoustic emission (AE) testing. This study presents an in-depth and systematic investigation of deformation, strength, and AE characteristics. The results show significant differences in deformation, strength, and acoustic emission characteristics for the rock under conventional triaxial and true triaxial compression tests, respectively. The peak strength, axial strain, lateral strain, and incremental strain (in unstable crack growth stage) increase with increasing confining pressure under conventional triaxial compression, and the AE count gradually decreases while shear crack proportion gradually increases, indicating that increasing confining pressure gradually inhibits the shear slip effect along fractures, delays perforation of the rock shear fracture surface, and enhances the ability of the rock to withstand deformation and load. Under true triaxial compression, the peak strength increases and then decreases with increasing intermediate principal stress σ2 and the axial strain ε1 and lateral strain ε2 gradually decrease; besides, the lateral strain (expansion) of the rock is mainly in the minimum principal stress σ3 direction, and lateral expansion tends to decrease before increasing. AE events first weaken and then enhance with increasing σ2, and the proportion of shear cracks increases first and then decreases, indicating that the confining pressure gradually changes from the shear slip effect that controls crack offset to the damage effect that promotes crack tension with increasing σ2. In addition, the protective effect of confining pressure improves when σ3 increases.

scholarly journals Effect of drainage and saturation on undrained shear strength for compacted sandy soils

2019 ◽  
Vol 92 ◽  
pp. 07003
Author(s):  
Yukio Nakata ◽  
Tetsuya Tashita ◽  
Hiromu Chibana ◽  
Kenji Matsukata
Keyword(s):  
Triaxial Compression ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Degree Of Saturation ◽  
Compression Tests ◽  
Compacted Soils ◽  
Partially Saturated ◽  
Saturated Condition ◽  
Undrained Strength ◽  
Triaxial Compression Tests

Collapses of embankments have occurred due to heavy rainfall. It is very important to understand the strength properties under various unsaturated, partially saturated and fully saturated conditions of compacted materials. So, a series of unsaturated and saturated triaxial compression tests for compacted soils have been conducted to understand the effects of drainage and saturation on undrained strength. Soil samples were collected from several road embankments to carry out the experiments. The undrained (CU) strength of compacted material decreased with increase in the degree of saturation. Especially, the strength decreased from partially saturated condition to fully saturated condition was remarkable. The decrease of the materials with volume contractive behaviour was appeared clearly.

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