Emploi d'une méthode psychrométrique dans des essais triaxiaux sur un limon remanié non saturé

1978 ◽  
Vol 15 (4) ◽  
pp. 501-509 ◽  
Author(s):  
Jean-Claude Verbrugge
Keyword(s):  
Water Content ◽  
Degree Of Saturation ◽  
Breaking Stress ◽  
Triaxial Tests ◽  
Peltier Effect ◽  
Interstitial Pressure ◽  
Experimental Relation

This paper summarizes the results obtained with triaxial tests made on an unsaturated loam. The originality of the tests proceeds from the use of a Peltier effect psychometric probe for the measurements of interstitial pressure. This had made it possible to study the variations of the breaking stress in terms of water content and suction of soil. The coefficient χ of Bishop at rupture was also studied in terms of those variables and of the degree of saturation. An experimental relation between χ and |s| is proposed.

Evaluation of the mechanical anisotropy of lacustrine smectite clays by triaxial test analysis

2022 ◽  
Author(s):  
Jubier Alonso Jiménez-Camargo ◽  
Dora Carreon-Freyre
Keyword(s):  
Water Content ◽  
Mechanical Response ◽  
Clayey Soil ◽  
Mechanical Anisotropy ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Particle Deformation ◽  
Relevant Variable ◽  
Pressure Equalization

Abstract This paper describes the role of fabric anisotropy during clayey soil deformation. A set of triaxial tests was performed on vertical and horizontal specimens of undisturbed smectite lake sediments from Jurica, Queretaro in Mexico. The results allowed to analyze the influence of bedding and discontinuities on the mechanical behavior of Jurica clays after failure. Tests with applied low strain rates allowed pore pressure equalization within specimens with different gravimetric water content and degree of saturation. Shear failure results of undrained tests showed that deformation distributes differently in both horizontal and vertical directions and that stress may be dissipated by pore collapses, fractures and particle deformation. The experimental evidence suggests that microfabric is a relevant variable in the overall mechanical response of clayey sediments that depends on the natural fabric (bedding and discontinuities), mineralogy, and water content. A detailed analysis of Young´s Moduli (E) showed the high variability of this parameter from 108 to 409 kg/cm2 (calculated at 30% of σdmax) and its dependence on the orientation of the specimen and the water content. In addition, p’-q’ graphs illustrate the relevance of considering mechanical anisotropy in clays and provide further insights to understand the role of smectites in progressive shear deformation.

Inclusion of specific water volume within an elasto-plastic model for unsaturated soil

1996 ◽  
Vol 33 (1) ◽  
pp. 42-57 ◽  
Author(s):  
S J Wheeler
Keyword(s):  
Water Content ◽  
Unsaturated Soil ◽  
Critical State ◽  
Constitutive Models ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Water Volume ◽  
Plastic Model ◽  
Elasto Plasticity ◽  
Soil Behaviour

Existing elasto-plastic critical state constitutive models for unsaturated soil provide no information on the variation of water content or degree of saturation. These models cannot therefore, for example, be used to predict unsaturated soil behaviour during undrained loading, when the variation of suction is determined by the requirement that water content remains constant. This problem has been tackled by extending an existing elasto-plastic model to include relationships describing the variation of specific water volume (the volume of water and solids in an element of soil containing unit volume of solids). The proposed form of the variation of specific water volume was based on consideration of the soil fabric, resulting in a coupled form of elasto-plastic behaviour. Predictions from the elasto-plastic model showed good agreement with the experimental results from suction-controlled triaxial tests on unsaturated samples of compacted speswhite kaolin. Normal compression lines for specific water volume at different values of suction were well predicted, as was the variation of specific water volume during wetting. Critical state values of specific water volume were slightly underestimated, but test paths for both drained and undrained shearing were predicted with reasonable success. Key words: compacted clays, constitutive model, critical state, elasto-plasticity, triaxial tests, unsaturated.

Using time domain reflectometry in triaxial testing

2000 ◽  
Vol 37 (6) ◽  
pp. 1325-1331
Author(s):  
J LH Grozic ◽  
M E Lefebvre ◽  
P K Robertson ◽  
N R Morgenstern
Keyword(s):  
Cyclic Loading ◽  
Water Content ◽  
Time Domain ◽  
Void Ratio ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Degree Of Saturation ◽  
Triaxial Testing ◽  
Empirical Correlations ◽  
Static And Cyclic Loading

Time domain reflectometry (TDR) can be used to determine the volumetric water content of soils. This note describes the utilization of a TDR miniprobe in triaxial testing. The TDR performance was examined with a series of tests that not only proved its reliability but also resulted in two empirical correlations. Using these correlations, the degree of saturation and volumetric water content during triaxial testing could be determined. The TDR was then put to use in a laboratory program designed to investigate the response of loose gassy sand under static and cyclic loading. Because of the TDR measurements it was possible to determine the degree of saturation and void ratio of the gassy specimens. The TDR miniprobe proved to be accurate, simple to use, and inexpensive to build.Key words: time domain reflectometry, TDR, triaxial testing, gassy, unsaturated.

Mitigation of liquefaction triggering due to bio-gas-induced desaturation using element tests and the strain energy approach

2021 ◽  
pp. 875529302110416
Author(s):  
Mohammad Hassan Baziar ◽  
Omid Eslami Amirabadi
Keyword(s):  
Pore Water ◽  
Strain Energy ◽  
Water Pressure ◽  
Gas Bubbles ◽  
Energy Approach ◽  
Degree Of Saturation ◽  
Ammonium Ion ◽  
Triaxial Tests ◽  
Treated Sample ◽  
Urease Enzyme

Currently, conventional remediation of liquefaction triggering may have many environmental effects, and this important issue has led researchers to look for more sustainable methods. In this research, one of the new bio-improvement methods (biogas) has been used to generate gas bubbles within a soil, susceptible to liquefaction. Using this method, two bio materials create ammonium ions and carbonate, in which ammonium ion is converted into nitrate due to the presence of bacteria in water, and they are eventually converted to nitrogen gas in an anaerobic condition. The nitrogen bubbles created in water reduce the soil’s degree of saturation, which in effect increases the soil’s resistance to liquefaction occurrence. In this study, two sources of urease enzyme were used to reduce the soil degree of saturation. The effects of various parameters, including the optimum concentration of each substance for optimum time to generate gas bubbles, as well as the effect of the oxygen amount in water were investigated using monotonic triaxial tests. The results illustrated that the addition of the mentioned two substances to the oxab (water with 60 ppm oxygen) or tap water decreased the pore water pressure due to desaturation. Finally, the energy approach was used to test the substance containing the amount of oxab with the highest decrease in pore water generation, here called “optimum selection,” in the cyclic triaxial device, and the results were analyzed to evaluate liquefaction occurrence. The outcome of these results revealed that compared with the strain energy of the non-treated sample, the treated sample had a much higher strain energy; in other words, the treated sample needed a larger amount of loading to trigger liquefaction.

Physical properties, electrical resistivity, and strength characteristics of carbonated silty soil admixed with reactive magnesia

2015 ◽  
Vol 52 (11) ◽  
pp. 1699-1713 ◽  
Author(s):  
G.H. Cai ◽  
Y.J. Du ◽  
S.Y. Liu ◽  
D.N. Singh
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Water Content ◽  
Unconfined Compressive Strength ◽  
Ground Improvement ◽  
Strength Characteristics ◽  
Degree Of Saturation ◽  
Initial Water Content ◽  
Silty Soil ◽  
Reactive Magnesia

Soil electrical resistivity has been used quite extensively for assessing mechanical properties of chemically treated soils in the recent past. One of the most innovative applications of this technique could be in the field of ground improvement wherein carbonated reactive magnesia (MgO) is employed for treating soils. With this in view, a systematic study that targets the application of electrical resistivity to correlate physical and strength characteristics of the carbonated reactive MgO-admixed silty soil is initiated, and its details are presented in this manuscript. To achieve this, reactive MgO-admixed soils were carbonized by exposing them to CO2 for different durations, and subsequently their electrical resistivity and unconfined compressive strength were measured. In this context, the role of a parameter, the ratio of the initial water content of the virgin soil to reactive MgO content (designated as w0/c), has been highlighted. It has also been demonstrated that w0/c is able to correlate, uniquely and precisely, with the physicochemical parameters of the soils (viz., unit weight, water content at failure, porosity, degree of saturation, and soil pH), electrical resistivity, and unconfined compressive strength at various carbonation times. In addition, microstructural properties have been obtained from the X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry analyses. These properties have been used to substantiate the findings related to the carbonation of the reactive MgO-admixed soils.

scholarly journals The Effect of Confining Pressure and Water Content on Energy Evolution Characteristics of Sandstone under Stepwise Loading and Unloading

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Shuren Wang ◽  
Paul Hagan ◽  
Yanhai Zhao ◽  
Xu Chang ◽  
Ki-Il Song ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Water Content ◽  
Elastic Energy ◽  
Strain Energy ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Energy Evolution ◽  
Evolution Characteristics ◽  
Loading And Unloading ◽  
Stepwise Loading

To investigate the mechanical properties and energy evolution characteristics of sandstone depending on the water contents and confining pressure, the uniaxial and triaxial tests were conducted. The test results show that the strain energy was stored in the sandstone samples at the prepeak stage, and that is suddenly released when the failure occurred, and energy dissipation is sharply increased at the postpeak stage. The damage and energy dissipation characteristics of the samples are observed clearly under the stepwise loading and unloading process. The critical strain energy and energy dissipation show a clear exponential relationship. The critical elastic energy decreases linearly as the water content increases. As the confining pressure increases, the critical elastic energy of the samples transforms from linear to exponential. The concept of energy enhancement factor is proposed to characterize the strengthening effect induced by the confining pressure on the energy storage capacity of the rock samples. The energy evolution of the sandstone samples is more sensitive to the confining pressure than that of the water content.

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