Effect of internal confinement on compression strength of frozen sand

1990 ◽  
Vol 27 (1) ◽  
pp. 8-18 ◽  
Author(s):  
Branko Ladanyi ◽  
Jean-François Morel
Keyword(s):  
Conceptual Model ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Senior Author ◽  
Test Results ◽  
Compression Tests ◽  
Frozen Sand ◽  
Theoretical Predictions ◽  
The Matrix ◽  
Triaxial Compression Tests

When a dense granular material with a viscoplastic matrix, such as ice, is submitted to uniaxial or triaxial compression, it is considered that one portion of its observed strength is due to the internal confinement resulting from tensile stresses generated in the matrix when it tends to oppose the dilation. Recently, a conceptual model of compression strength behaviour of such dilatant materials was developed by the senior author. This paper presents the model and describes an experimental study intended to check its validity. For this purpose, a series of triaxial compression tests on both frozen and unfrozen sand at carefully controlled densities was performed. The test results give a clear support to the theoretical predictions of the contribution of dilatancy hardening to the strength of a dense frozen sand. Key words: frozen sand, compression strength, triaxial compression tests, pore ice, cavitation, dilatancy hardening, conceptual model.

Behaviors of Xiashu Loess in the Lower Reaches of China’s Yangtze River under Triaxial Compression and the Microscopic Explanations

2016 ◽  
Vol 858 ◽  
pp. 91-97
Author(s):  
Jun Hua Xiao ◽  
Wen Qi Zheng
Keyword(s):  
Mechanical Properties ◽  
Yangtze River ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Processing Technique ◽  
Point Of View ◽  
Image Processing Technique ◽  
Test Results ◽  
Compression Tests ◽  
Triaxial Compression Tests

To investigate the macroscopic mechanical properties of undisturbed structural Xiashu loess in the lower reaches of China’s Yangtze River under triaxial compression, and obtain the intrinsic explanations for the macroscopic mechanical properties from the microscopic point of view, in laboratory, triaxial compression tests were carried out, microstructure images of sheared samples were collected by scanning electron microscope (SEM), and quantitative parameters of microstructure (mainly about particle or pore size, distribution, and alignment) were extracted by digital image processing technique. Based on the test results, the deviator stress-strain relationships of both undisturbed and remoulded Xiashu loess, the structural strength, and the microstructural evolution mechanism about the formation of shear failure zone of Xiashu loess under triaxial compression were analyzed.

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.

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.

Swelling and softening behaviour of La Biche shale

1998 ◽  
Vol 35 (2) ◽  
pp. 206-221 ◽  
Author(s):  
RCK Wong
Keyword(s):  
Electrolyte Concentration ◽  
Triaxial Compression ◽  
Strength Loss ◽  
Test Results ◽  
Compression Tests ◽  
Swelling Behaviour ◽  
One Dimensional ◽  
Failure Theory ◽  
Free Swell ◽  
Triaxial Compression Tests

Free swell, semiconfined swell, and one-dimensional oedometer swell tests were performed on La Biche shale specimens in solutions of different salinities. The swelling behaviour of La Biche shale was found to be highly anisotropic and dependent on electrolyte concentration, stress, and swelling history. Drained triaxial compression tests were conducted on La Biche shale specimens subjected to different degrees of swelling. The test results indicate that the Young's modulus decreases with increasing swelling. The strength loss due to swelling can be explained by the Hvorslev failure theory. A descending power law is proposed to describe the cohesion reduction with the swelling.Key words: shale, salinity, swelling, strength weakening, modulus softening.

Experimental study on variability in mechanical properties of a frozen sand as determined in triaxial compression tests

2015 ◽  
Vol 11 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Ling Ma ◽  
Jilin Qi ◽  
Fan Yu ◽  
Xiaoliang Yao
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Triaxial Compression ◽  
Compression Tests ◽  
Frozen Sand ◽  
Triaxial Compression Tests

Geosynthetic-Encased Sand Column Behavior under Triaxial Test Simulation

2012 ◽  
Vol 594-597 ◽  
pp. 581-584
Author(s):  
Yung Shan Hong ◽  
Cho Sen Wu ◽  
Chiang Sen Sun
Keyword(s):  
Triaxial Test ◽  
Triaxial Compression ◽  
Chamber Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Resistant Material ◽  
Sand Column ◽  
Reinforcing Effects ◽  
Triaxial Compression Tests ◽  
Granular Column

Encasing a cylindrical granular column with tensile resistant material is proven an effective practice to improve granular column strength. Laboratory triaxial compression tests were conducted on encased granular columns to study the tensile resistant material reinforcing effects. This study explores the behavior of geosynthetic-encased sand columns using a converted approach to reduce laborious efforts. The encased column behavior is simulated by applying persistently increased chamber pressure to unreinforced sand column specimens. Three column specimen diameters, 5, 7 and 10 cm, were employed to study the scale effect. The test results indicate that the converted approach simulates larger diameter encased column well.

A Simple Unconsolidated Undrained Triaxial Compression Test Emulator

2015 ◽  
Vol 771 ◽  
pp. 104-107
Author(s):  
Riska Ekawita ◽  
Hasbullah Nawir ◽  
Suprijadi ◽  
Khairurrijal
Keyword(s):  
Triaxial Compression ◽  
Measurement Data ◽  
Radial Strain ◽  
Compression Tests ◽  
Viscous Effects ◽  
Axial Pressure ◽  
Strain Stress ◽  
The University ◽  
And Storage ◽  
Triaxial Compression Tests

An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

scholarly journals Semi-empirical elastic–thermoviscoplastic model for clay

2016 ◽  
Vol 53 (10) ◽  
pp. 1583-1599 ◽  
Author(s):  
David Kurz ◽  
Jitendra Sharma ◽  
Marolo Alfaro ◽  
Jim Graham
Keyword(s):  
Stress Level ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Compression Tests ◽  
One Dimensional ◽  
Load Duration ◽  
Compression Creep ◽  
Overconsolidated Clays ◽  
Semi Empirical ◽  
Triaxial Compression Tests

Clays exhibit creep in compression and shear. In one-dimensional compression, creep is commonly known as “secondary compression” even though it is also a significant component of deformations resulting from shear straining. It reflects viscous behaviour in clays and therefore depends on load duration, stress level, the ratio of shear stress to compression stress, strain rate, and temperature. Research described in the paper partitions strains into elastic (recoverable) and plastic (nonrecoverable) components. The plastic component includes viscous strains defined by a creep rate coefficient ψ that varies with plasticity index and temperature (T), but not with stress level or overconsolidation ratio (OCR). Earlier elastic–viscoplastic (EVP) models have been modified so that ψ = ψ(T) in a new elastic–thermoviscoplastic (ETVP) model. The paper provides a sensitivity analysis of simulated results from undrained (CIŪ) triaxial compression tests for normally consolidated and lightly overconsolidated clays. Axial strain rates range from 0.15%/day to 15%/day, and temperatures from 28 to 100 °C.

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