Creep and strength testing of frozen saline fine-grained soils

1984 ◽  
Vol 21 (3) ◽  
pp. 518-529 ◽  
Author(s):  
J. F. Nixon ◽  
G. Lem
Keyword(s):  
Shear Strength ◽  
Creep Rate ◽  
Constant Strain Rate ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Saline Soils ◽  
Creep Data ◽  
Creep Tests ◽  
Test Environment ◽  
Fine Grained

Little creep data is available for frozen, fine-grained saline soils. Salinity accelerates the creep rate of a frozen soil under load and reduces its shear strength owing to the higher unfrozen water contents in the pore phase. Creep data for saline fine-grained soils are required by engineers and scientists working in areas of coastal or offshore permafrost. The data are also used in projects involving artificial freezing of saline soils.This paper describes the results of 34 creep tests and 11 time-dependent strength tests carried out on saline soils. The tests were carried out for two different research programs; consequently, two different fine-grained soil types were used. Most of the tests were carried out in a constant stress and constant temperature creep test environment. Some were completed in a triaxial (constant strain rate) test format, in order to extend the data base to an area of higher strain rates. The range of temperatures was −2.3 to −25 °C, the range of stresses in the creep tests was 30–400 kPa, and the salinity was varied from 0–35 parts per thousand (ppt). Particular attention was paid to the lower stresses (30–200 kPa) and intermediate to high salinities (18–35 ppt). A high percentage of the creep tests was completed in the temperature range −5 to −10 °C, as this appears to be a typical ground temperature in coastal permafrost areas in Arctic Canada.Results indicate that the presence of pore fluid with a salinity approaching that of seawater causes a 10- to 100-fold increase in uniaxial creep rate, which can result in significant decreases in shear strength and foundation bearing capacity in saline permafrost areas.Soil resistivity tests were also carried out on frozen samples of different salinities. A strong correlation between resistivity and pore water salinity emerged. This has application in the interpretation of results from electrical resistivity surveys in permafrost. Key words: permafrost, saline, creep, strength, resistivity, fine-grained, offshore permafrost.

Concerning a Creep Surface Derived From a Multiple Integral Representation for 304 Stainless Steel Under Combined Tension and Torsion

1978 ◽  
Vol 45 (4) ◽  
pp. 773-779 ◽  
Author(s):  
R. Mark ◽  
W. N. Findley
Keyword(s):  
Stainless Steel ◽  
Creep Rate ◽  
Integral Representation ◽  
Power Function ◽  
Multiple Integral ◽  
304 Stainless Steel ◽  
Creep Data ◽  
Creep Tests ◽  
Third Order ◽  
Good Agreement

It is shown that a creep surface, defined in terms of a prescribed creep rate, can be determined from the multiple integral formulation representing the creep data. The creep surface for 304 stainless steel was found to be in good agreement with a Mises ellipse. Observed creep rate vectors for this alloy were found to be normal to a Mises ellipse. These results were obtained from creep tests performed on 304 stainless steel under combined tension and torsion at 593°C (1100°F). Creep strains observed for at least 100 hr were adequately represented by a power function of time, the exponent of which was independent of stress. A third-order multiple integral representation together with a limiting stress below which creep does not occur was employed to describe satisfactorily the constant stress creep data.

Strength of frozen saline soils

1995 ◽  
Vol 32 (2) ◽  
pp. 336-354 ◽  
Author(s):  
E.G. Hivon ◽  
D.C. Sego
Keyword(s):  
Water Content ◽  
Fine Particles ◽  
Constant Strain Rate ◽  
Significant Loss ◽  
Time Domain Reflectometry ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Strain Behavior ◽  
Unfrozen Water Content ◽  
The Time Domain

This paper summarizes an extensive laboratory program undertaken to study the influence of soil type, temperature, and salinity on the strength of three different frozen soils under conditions of unconfined constant strain rate tests. Since the effects of temperature and salinity can be unified by studying the variation of unfrozen water content, measurements of unfrozen water at different temperatures were carried out using the time-domain reflectometry (TDR) method. The stress–strain behavior is influenced by the presence of fine particles in the soil, and an increase in temperature and salinity (unfrozen water content) causes a significant loss of strength. For each soil tested, a predictive model of its strength in terms of salinity and temperature (unfrozen water content) is presented. Key words : frozen soil, saline, unfrozen water, strength.

High Temperature Creep of Alpha-2 Ti-34mo1%Al Polycrystals

1994 ◽  
Vol 364 ◽  
Author(s):  
Hiroshi Oikawa ◽  
Toshihiko Fukuda ◽  
Makoto Ohtsuka
Keyword(s):  
Creep Rate ◽  
Minimum Creep Rate ◽  
Single Phase ◽  
Creep Condition ◽  
Primary Creep ◽  
High Temperature Creep ◽  
Creep Tests ◽  
Creep Stage ◽  
Fine Grained ◽  
Equiaxed Grains

AbstractConstant-stress compressive creep tests were carried out on an Al-rich a2 single-phase material, which had equiaxed-grains of 60μim in grain size, at 1050∼1250 K under 100∼500MPa. The type of the primary creep stage and the microstructures developed during creep depend greatly on the creep condition. The minimum creep-rate, however, can be represented by one set of parameters over the whole range of experimental condition. The stress exponent is 5.0±0.2 and the (modulus-compensated) activation energy is 360 ± 10kJ/mol. The Dorn-type plot of the minimum creep rate reveals that the normalized creep strength of fine-grained Ti-34mol%Al is not greatly different from that of disordered solid-solution hardened alloys.

Mathematical descriptions for the behaviour of ice-rich frozen soils at temperatures close to 0 °C

2005 ◽  
Vol 42 (2) ◽  
pp. 431-442 ◽  
Author(s):  
Lukas U Arenson ◽  
Sarah M Springman
Keyword(s):  
Strain Rate ◽  
Creep Strain ◽  
Mechanical Response ◽  
Constant Strain Rate ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Strain Rates ◽  
Frozen Soils ◽  
Apparent Cohesion ◽  
Thermomechanical Behaviour

With the use of creep and constant strain rate (CSR) tests, mathematical formulations were found that describe the thermomechanical behaviour of ice-rich frozen soils. A Glen-type relationship was chosen for the formulation of minimum creep strain rates at temperatures between –4 °C and –1 °C. The shear strength of the material could be described by a Mohr–Coulomb failure criterion. Furthermore, it was possible to compare the creep behaviour with the strength of similar soils under constant strain rates. The minimum creep strain rate increases proportionally as the temperature approaches the melting point of the ice, which can be attributed to the increasing amount of unfrozen water, which strongly influences the mechanical response. Even though only a few tests could be used for the determination of the angle of friction and the apparent cohesion, the trend showed that the volumetric ice content influences both parameters, but only the latter seems to be influenced by the temperature and the applied compression strain rate.Key words: permafrost, frozen soil, creep, strength.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

scholarly journals Assessment for Thermal Conductivity of Frozen Soil Based on Nonlinear Regression and Support Vector Regression Methods

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Fu-Qing Cui ◽  
Wei Zhang ◽  
Zhi-Yun Liu ◽  
Wei Wang ◽  
Jian-bing Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Support Vector Regression ◽  
Nonlinear Regression ◽  
Prediction Accuracy ◽  
Prediction Models ◽  
Frozen Soil ◽  
Support Vector ◽  
Soil Thermal Conductivity ◽  
Fine Grained ◽  
Fine Grained Soil

The comprehensive understanding of the variation law of soil thermal conductivity is the prerequisite of design and construction of engineering applications in permafrost regions. Compared with the unfrozen soil, the specimen preparation and experimental procedures of frozen soil thermal conductivity testing are more complex and challengeable. In this work, considering for essentially multiphase and porous structural characteristic information reflection of unfrozen soil thermal conductivity, prediction models of frozen soil thermal conductivity using nonlinear regression and Support Vector Regression (SVR) methods have been developed. Thermal conductivity of multiple types of soil samples which are sampled from the Qinghai-Tibet Engineering Corridor (QTEC) are tested by the transient plane source (TPS) method. Correlations of thermal conductivity between unfrozen and frozen soil has been analyzed and recognized. Based on the measurement data of unfrozen soil thermal conductivity, the prediction models of frozen soil thermal conductivity for 7 typical soils in the QTEC are proposed. To further facilitate engineering applications, the prediction models of two soil categories (coarse and fine-grained soil) have also been proposed. The results demonstrate that, compared with nonideal prediction accuracy of using water content and dry density as the fitting parameter, the ternary fitting model has a higher thermal conductivity prediction accuracy for 7 types of frozen soils (more than 98% of the soil specimens’ relative error are within 20%). The SVR model can further improve the frozen soil thermal conductivity prediction accuracy and more than 98% of the soil specimens’ relative error are within 15%. For coarse and fine-grained soil categories, the above two models still have reliable prediction accuracy and determine coefficient (R2) ranges from 0.8 to 0.91, which validates the applicability for small sample soils. This study provides feasible prediction models for frozen soil thermal conductivity and guidelines of the thermal design and freeze-thaw damage prevention for engineering structures in cold regions.

An Experimental Study on the Effect of Prior Plastic Straining on Creep Behavior of 304 Stainless Steel

1993 ◽  
Vol 115 (2) ◽  
pp. 200-203 ◽  
Author(s):  
Z. Xia ◽  
F. Ellyin
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Rate ◽  
Creep Behavior ◽  
Test Procedure ◽  
Constant Strain Rate ◽  
304 Stainless Steel ◽  
Creep Model ◽  
Plastic Strain Rate ◽  
Creep Tests

Constant strain-rate plastic straining followed by creep tests were conducted to investigate the effect of prior plastic straining on the subsequent creep behavior of 304 stainless steel at room temperature. The effects of plastic strain and plastic strain-rate were delineated by a specially designed test procedure, and it is found that both factors have a strong influence on the subsequent creep deformation. A creep model combining the two factors is then developed. The predictions of the model are in good agreement with the test results.

Residual shear strength of fine-grained soils and soil–solid interfaces at low effective normal stresses

2015 ◽  
Vol 52 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Hisham T. Eid ◽  
Ruslan S. Amarasinghe ◽  
Khaled H. Rabie ◽  
Dharma Wijewickreme
Keyword(s):  
Shear Strength ◽  
Large Strain ◽  
Laboratory Research ◽  
Normal Stresses ◽  
Interface Shear ◽  
Residual Shear Strength ◽  
Fine Grained ◽  
Solid Interface ◽  
Wide Range ◽  
Shear Area

A laboratory research program was undertaken to study the large-strain shear strength characteristics of fine-grained soils under low effective normal stresses (∼3–7 kPa). Soils that cover a wide range of plasticity and composition were utilized in the program. The interface shear strength of these soils against a number of solid surfaces having different roughness was also investigated at similar low effective normal stress levels. The findings contribute to advancing the knowledge of the parameters needed for the design of pipelines placed on sea beds and the stability analysis of shallow soil slopes. A Bromhead-type torsional ring-shear apparatus was modified to suit measuring soil–soil and soil–solid interface residual shear strengths at the low effective normal stresses. In consideration of increasing the accuracy of assessment and depicting the full-scale field behavior, the interface residual shear strengths were also measured using a macroscale interface direct shear device with a plan interface shear area of ∼3.0 m2. Correlations are developed to estimate the soil–soil and soil–solid interface residual shear strengths at low effective normal stresses. The correlations are compared with soil–soil and soil–solid interface drained residual shear strengths and correlations presented in the literature.

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