scholarly journals Simulation of Stress Paths Derived from FEM Analysis in Triaxial Tests

2013 ◽  
Vol 59 (1) ◽  
pp. 119-129
Author(s):  
M. Kowalska
Keyword(s):  
Laboratory Tests ◽  
Equivalent Stress ◽  
Fem Analysis ◽  
Stress Path ◽  
Triaxial Tests ◽  
Laboratory Equipment ◽  
Geotechnical Parameters ◽  
Triaxial Apparatus ◽  
Triaxial Extension

Abstract Reliable estimation of geotechnical parameters is often based on reconstruction of a complete loading process of subsoil on a specimen in laboratory tests. Unfortunately laboratory equipment available in many laboratories is sometimes limited to just a triaxial apparatus - the use of which generates difficulties whenever a non-axisymmetric problem is analysed.The author suggests two simple operations that may be done to improve the quality of simulation in triaxial tests. The first one is based on the use of triaxial extension along the segments of the stress path p’-q-θ for which the Lode’s angle values are positive. The second one consists in a modification of the equivalent stress value in such a way that the current stress level in the specimen complies with results of FEM analysis.

A Simple and Practicable Approach on Implementing for the Reduced Triaxial Extension by the Conventional Triaxial Apparatus

2011 ◽  
Vol 250-253 ◽  
pp. 2089-2092
Author(s):  
Rong Jian Li ◽  
Xi An Li ◽  
Gao Feng Che ◽  
Wen Zheng ◽  
Wen Jun Chen
Keyword(s):  
Triaxial Compression ◽  
Stress Path ◽  
Test Results ◽  
Triaxial Apparatus ◽  
Eolian Sand ◽  
Conventional Triaxial Compression ◽  
The Difference ◽  
Shear Behaviors ◽  
The Impact ◽  
Triaxial Extension

Stress path is one of the very important factors of soil strength. It is significant to study the strength and reveal the importance of the impact of sand in different stress path conditions. Firstly, an ameliorating approach on implementing for the reduced triaxial extension by the conventional triaxial apparatus was discussed. Then, In order to study shear behaviors of the eolian sand under different stress path, two monotonic shearing tests with the conventional triaxial compression and the reduced triaxial extension stress path were performed and analyzed. The test results not only indicate that the amelioration on conventional triaxial apparatus is simple, practicable and inexpensive, but also reveal the difference of strength’s parameter between the reduced triaxial extension and conventional triaxial compression stress path. In sum, the stress path has important effect on the strength of the eolian sand.

Quality of laboratory tests as a basic component of treatment effectiveness

2020 ◽  
pp. 38-47
Author(s):  
Tamara Silkina ◽  
Olga Petrova
Keyword(s):  
General Practitioner ◽  
Russian Federation ◽  
Laboratory Tests ◽  
Treatment Effectiveness ◽  
Outpatient Setting ◽  
Basic Component ◽  
The Russian Federation

The article presents analysis of modern laboratory technologies and requirements for the quality of laboratory tests in the Russian Federation. Basic rules that improve the quality of laboratory tests at the preanalytical, analytical and postanalytical stage are studied on the example of tests in the Laboratory Hemotest. The optimal list of laboratory tests used in the practice of a general practitioner and organizational options for performing laboratory tests, the features of the process that affect the speed of obtaining a result by a doctor in an outpatient setting and in hospital, are presented.

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

Effects of Stress Path and Stress History on the Stiffness of Reconstituted London Clay

1986 ◽  
Vol 2 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Stress History ◽  
Strain Behaviour ◽  
Reconstituted Soil ◽  
Path Dependent ◽  
London Clay ◽  
Soil Behaviour

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.

scholarly journals Defining features in the kinetics of sodium carbonate-bicarbonate solution carbonization and the quality of the resulting sodium bicarbonate crystals

2021 ◽  
Vol 4 (10(112)) ◽  
pp. 38-44
Author(s):  
Mykola Porokhnia ◽  
Musii Tseitlin ◽  
Svitlana Bukhkalo ◽  
Vladimir Panasenko ◽  
Tetiana Novozhylova
Keyword(s):  
Carbon Dioxide ◽  
Sodium Bicarbonate ◽  
Sodium Carbonate ◽  
Diffusion Resistance ◽  
Crystal Formation ◽  
Gas Velocity ◽  
Laboratory Equipment ◽  
Gas Consumption ◽  
Kinetics Of

This paper reports a study into the influence of temperature and gas consumption on the carbonization kinetics (saturation with carbon dioxide) of sodium carbonate-bicarbonate solution. The study also examined the quality and speed of crystal formation in this process. This research is predetermined by the environmental problems faced by modern enterprises that produce purified sodium bicarbonate – an insufficient degree of carbonization and, as a result, excessive air pollution with carbon dioxide, which did not participate in the reaction during the process. This study addresses these particular issues. As a result of using specialized laboratory equipment, it was found that an increase in the absorbent temperature from 79 to 85 °C leads to a decrease in the maximum degree of carbonization of the solution from 64 to 59 %. In contrast, the quality of the resulting sodium bicarbonate crystals improves but only in the range from 79 to 82 °C. With a further increase in temperature, the quality stabilizes. It is shown that the carbonization rate increases with increasing specific consumption of the absorbent (carbon dioxide) and is characterized by a negative correlation with the value of oversaturation of the absorbent in terms of NaНCO3. The quality of sodium bicarbonate crystals decreases with increasing gas velocity. Thus, it was reasonable to assume that the established dependence of the kinetics of carbonization of Na2CO3 and NaНCO3 solution on the gas velocity in the apparatus is explained by the inhibition of СО2 absorption, which is caused by the diffusion resistance of sodium bicarbonate crystallization. To improve the quality of crystals and the productivity of carbonization by reducing the supersaturation in terms of NaНCO3, it is recommended to introduce a seed crystal in the zone of binding of crystals in the carbonization columns.

scholarly journals Testing the Impact of Waste from Anaerobic Digestion (Enriched with an Organic Component) on the Quality of Agricultural Land

2017 ◽  
Vol 63 (4) ◽  
pp. 33-38
Author(s):  
Jana Kodymová ◽  
Miroslav Kyncl ◽  
Hana Švehláková ◽  
Magdaléna Bártková
Keyword(s):  
Anaerobic Digestion ◽  
Field Trial ◽  
Laboratory Tests ◽  
Agricultural Land ◽  
Mineral Fertilizer ◽  
Organic Component ◽  
Carbon And Nitrogen ◽  
Macro And Micronutrients ◽  
The Impact

Abstract Waste from anaerobic digestion is considered as a mineral fertilizer and it is usually applied to agricultural land. The aim of our attempt was to enrich this waste from anaerobic digestion (digestate) with an organic component (in our case represented by haylage). For this purpose, we made different mixtures of digestate and haylage in different weight ratios. In the field trial, the effect of these mixtures on the soil, under standard agricultural conditions, was monitored. Selected accessible nutrients (P, K, Mg, Mn, Ca) and the amount of carbon and nitrogen in the soil were monitored. The results of the laboratory tests confirmed that the areas where the sowing and digestate mixtures were applied showed greater amounts of macro- and micronutrients in plant-accessible forms than the surface fertilized only with digestate or areas fertilized only with standard fertilizers.

scholarly journals GEOTECHNICAL CHARACTERISTICS OF EMBANKMENT ALONG THE RAILWAY ROUTE OF ENTITY BORDER OF FEDERATION OF BIH – MAGLAJ, SECTION km 103+500 MAGLAJ

2017 ◽  
Vol 1 (16) ◽  
Author(s):  
Neđo Đurić
Keyword(s):  
European Union ◽  
Laboratory Tests ◽  
Soil Depth ◽  
The Other ◽  
Geotechnical Characteristics ◽  
Time Period ◽  
European Union Countries ◽  
Improvement Measures ◽  
Train Speed

Railway route from entity border to Maglaj is on corridor V of railways that connects Adriatic seawith European Union countries. More precisely, it is on the railway Samac – Sarajevo that was builtduring the fifties. From Doboj to Zenica exist two tracks, one built in 1947. and the other thirty yearslater. In time, the railway worn out, since it was not maintained properly during its exploitation, soallowed train speed is 40 km/h. Reconstruction of railway had previously started on sections with aimto achieve the level of train speed to 120 km/h.Terrain research in order to overview quality of material on which the railway is laid, and immediateenvironment that has effect on railway route, were conducted by sections, from which section km103+500 – Maglaj is one of the most important considering characteristics of the terrain on which theroute passes. Research along railway route were conducted by using research trial pits from both sidesand in between tracks, to depth of entry in basic soil. Depth of research works is different for old andnew track, considering the way of construction in time period of 30 years. Beyond narrow corridor ofrailway route research of characteristics of the terrain were not conducted, because of inability toaccess due to mining. Results of terrain and laboratory tests showed geotechnical characteristics ofmaterial, based on which were given quality improvement measures for deposited materials, and basefor reconstruction of railway.

The strength and dilatancy of sand

1992 ◽  
Vol 29 (3) ◽  
pp. 522-526 ◽  
Author(s):  
Y. P. Vaid ◽  
S. Sasitharan
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Friction Angle ◽  
Stress Path ◽  
Triaxial Tests ◽  
Confining Stress ◽  
Peak Friction Angle ◽  
Loading Direction ◽  
Dilation Rate ◽  
Unique Relationship

The effects of stress path and loading direction in the triaxial test on strength and dilatancy of sand are investigated. It is shown that the unique relationship observed between peak friction angle and dilation rate at peak in conventional triaxial tests is followed regardless of stress path, confining stress at failure, relative density, and the mode of loading (compression or extension). Key words : sand, peak friction angle, dilatancy, stress path, triaxial test.

scholarly journals Creep behaviour of undisturbed London Clay in triaxial stress space

2019 ◽  
Vol 92 ◽  
pp. 05006
Author(s):  
Truong Le ◽  
David Airey ◽  
Jamie Standing
Keyword(s):  
Creep Strain ◽  
Creep Behaviour ◽  
Stress Path ◽  
Triaxial Stress ◽  
Strain Component ◽  
Compression Tests ◽  
Stress Space ◽  
Triaxial Apparatus ◽  
London Clay ◽  
Creep Deformations

The evolution of the creep strain component in triaxial stress space was investigated through performing a series of multistage drained compression tests on London Clay using a specially designed locally instrumented triaxial apparatus. Experiments along specifically defined stress paths showed significant rotation of the local creep strain component as the samples were sheared towards failure. The results indicate a need for a more complex plastic potential function to correctly predict incremental creep strains at different states in triaxial stress space. Creep deformations for stress path controlled drained compression tests were also found to require a reinterpretation of the classic secondary compression behaviour. Creep strain-rates were found to fall well outside the normal power decay function. Test data and previously reported drained creep test results on London Clay have been combined to provide a complete understanding of the incremental creep component. The experiments show how creep behaviour significantly depends on the stress conditions imposed and the approaching strain rate.

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