Ice triaxial deformation and fracture

AbstractAn experimental investigation into the mechanical behaviour of polycrystalline ice in triaxial compression has been conducted using conditions generally favourable to brittle fracture and microcracking. Under triaxial stresses at high strain rate, ice failure occurs by abrupt shear fracturing, generally inclined at about 45° to the maximum principal stress. At −20°C, such failure is suppressed by the imposition of a small confining pressure, allowing a transition to ductile-type flow accompanied by distributed microcracking, but at —40°C shear fracture persists under confinement of up to at least 50 MPa. For low confining pressures (< 10 MPa), brittle strength is strongly pressure-dependent; above this it is pressure-independent. Evidence is presented that suggests this may reflect a change from a fracture process influenced by friction to fracture initiated by localized yielding. Ductile yield strength is found to be little influenced by confining pressure despite the inhibition of cracking that leads to greatly contrasting observed crack densities. Flow conforms to the well-known power law for ice withQ= 69 J mol−1andn= 4.2 over the temperature range −20° to −4-5° C Under these conditions, microcracking in ice appears to remain remarkably stable and non-interacting.

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Ice triaxial deformation and fracture

Journal of Glaciology ◽

10.1017/s0022143000007395 ◽

1994 ◽

Vol 40 (135) ◽

pp. 305-318 ◽

Cited By ~ 68

Author(s):

M.A. Rist ◽

S.A.F Murrell

Keyword(s):

Shear Fracture ◽

Triaxial Compression ◽

Confining Pressure ◽

Maximum Principal Stress ◽

Brittle Strength ◽

Independent Evidence ◽

Polycrystalline Ice ◽

Confining Pressures ◽

Pressure Independent ◽

Ice Failure

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Triaxial tests on snow at low strain rate. Part II. Constitutive behaviour

Journal of Glaciology ◽

10.3189/172756503781830890 ◽

2003 ◽

Vol 49 (164) ◽

pp. 91-101 ◽

Cited By ~ 33

Author(s):

Carlo Scapozza ◽

Perry Bartelt

Keyword(s):

Strain Rate ◽

Yield Stress ◽

Power Law ◽

Triaxial Compression ◽

Confining Pressure ◽

Triaxial Tests ◽

Constitutive Behaviour ◽

Fine Grained ◽

Polycrystalline Ice ◽

Confining Pressures

AbstractFine-grained, dry snow with a density range of 190–435 kg m−3 was tested in triaxial compression at −12°C with confining pressures varying between 0 and 40 kPa. The tests were strain-rate controlled, with strain rates ranging between 7.4 × 10−7 s−1 and 6.6 × 10−5 s−1. The analysis of the test results revealed that the relationship between yield stress and viscous strain rate is best given by a power law, similar to polycrystalline ice. However, the power-law exponent n is a function of density and varies between 1.8 (low-density snow, ρ < 200 kg m−3) and 3.6 (high-density snow, ρ > 320 kg m−3). The tests also showed that lower-density snow displays a significant non-linear stress–strain response before yielding. Two further aspects of the constitutive behaviour of snow were identified: (1) the strainrate independence of the post-yield work-hardening behaviour in compression and (2) the independence of the axial yield stress in relation to the confining pressure. The experimental observations are discussed with respect to the mechanical properties of polycrystalline ice, which is the constituent material of the load-bearing ice skeleton.

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Mechanical behaviour of powders using a medium pressure flexible boundary cubical triaxial tester

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1243/095440803322328881 ◽

2003 ◽

Vol 217 (3) ◽

pp. 233-241 ◽

Cited By ~ 11

Author(s):

F Li ◽

V M Puri

Keyword(s):

Shear Modulus ◽

Mechanical Behaviour ◽

Triaxial Compression ◽

Three Dimensional ◽

Volumetric Strain ◽

Confining Pressure ◽

Alumina Powder ◽

Medium Pressure ◽

Mean Pressure ◽

Confining Pressures

A medium pressure (<21 MPa) flexible boundary cubical triaxial tester was designed to measure the true three-dimensional response of powders. In this study, compression behaviour and strength of a microcrystalline cellulose powder (Avicel® PH102), a spray-dried alumina powder (A16SG), and a fluid-bed-granulated silicon nitride based powder (KY3500) were measured. To characterize the mechanical behaviour, three types of triaxial stress paths, that is, the hydrostatic triaxial compression (HTC), the conventional triaxial compression (CTC), and the constant mean pressure triaxial compression (CMPTC) tests were performed. The HTC test measured the volumetric response of the test powders under isostatic pressure from 0 to 13.79MPa, during which the three powders underwent a maximum volumetric strain of 40.8 per cent for Avicel® PH102, 30.5 per cent for A16SG, and 33.0 per cent for KY3500. The bulk modulus values increased 6.4-fold from 57 to 367MPa for Avicel® PH102, 3.7-fold from 174 to 637 MPa for A16SG, and 8.1-fold from 74 to 597MPa for KY3500, when the isotropic stress increased from 0.69 to 13.79 MPa. The CTC and CMPTC tests measured the shear response of the three powders. From 0.035 to 3.45MPa confining pressure, the shear modulus increased 28.7-fold from 1.6 to 45.9MPa for Avicel® PH102, 35-fold from 1.7 to 60.5MPa for A16SG, and 28.5-fold from 1.5 to 42.8MPa for KY3500. In addition, the failure stresses of the three powders increased from 0.129 to 4.41 MPa for Avicel® PH102, 0.082 to 3.62 MPa for A16SG, and 0.090 to 4.66MPa for KY3500, respectively, when consolidation pressure increased from 0.035 to 3.45MPa. In addition, the shear modulus and failure stress values determined from the CTC test at 2.07, 2.76, and 3.45MPa confining pressures are consistently greater than those from the CMPTC test at the same constant mean pressures. This observation demonstrates the influence of stress paths on material properties. The CTT is a useful tool for characterizing the three-dimensional response of powders and powder mixtures.

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Microcracking and the failure of polycrystalline ice under triaxial compression

Journal of Glaciology ◽

10.3189/s0022143000009606 ◽

1992 ◽

Vol 38 (128) ◽

pp. 65-76 ◽

Cited By ~ 1

Author(s):

P. Kalifa ◽

G. Ouillon ◽

P. Duval

Keyword(s):

Triaxial Compression ◽

Peak Stress ◽

Confining Pressure ◽

Triaxial Tests ◽

Strain History ◽

Compression Tests ◽

Brittle Transition ◽

Polycrystalline Ice ◽

Strain Components

AbstractTriaxial and uniaxial compression tests have been carried out at –10°C on granular ice in order to study the role of microcracking on failure in the ductile-brittle transition zone. In the triaxial tests, the effect of confining pressure and strain rate on the crack population, as well as on strength and strain at the peak stress, was investigated. In the uniaxial tests, we measured the evolution of elastic and non-elastic components of deformation with the stress-strain history. The concept of effective stress, with a single scalar damage variable, was used to calculate the effect of microcracking on the strain components.

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The Effect of Confining Pressure on the Mechanical Properties of Sand–Ice Materials

Journal of Glaciology ◽

10.1017/s0022143000031889 ◽

1973 ◽

Vol 12 (66) ◽

pp. 469-481 ◽

Cited By ~ 42

Author(s):

Bernard D. Alkire ◽

Orlando B. Andersland

Keyword(s):

Axial Strain ◽

Triaxial Compression ◽

Confining Pressure ◽

Silica Sand ◽

Creep Tests ◽

Ice Volume ◽

Coulomb Failure ◽

Confining Pressures ◽

Sand Material ◽

Cylindrical Samples

Cylindrical samples containing 0.59 mm to 0.84 mm diameter silica sand at about 97% and 55% ice saturation (the ratio of ice volume to sand pore volume) were tested at a temperature of −12° C in triaxial compression. Both constant axial strain-rate tests and step-stress creep tests provide information on the influence of confining pressure on the shear strength and creep behavior of the sand–ice material. Changes in the degree of ice saturation help show the influence of the ice matrix versus the sand material on the mechanical behavior. Data are discussed in terms of the Mohr–Coulomb failure law and creep theories. It is shown that the cohesive component of strength depends on response of the ice matrix, whereas the frictional component of strength responds in a manner very similar to unfrozen sand tested at high confining pressures. Experimental data show that creep rates decrease exponentially and creep strength increases with an increase in confining pressure.

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Investigation on the relationship between CT numbers and marble failure under different confining pressures

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2021-0070 ◽

2021 ◽

Vol 60 (1) ◽

pp. 846-852

Author(s):

Yang Yan-Shuang ◽

Li Kai-Yue ◽

Zhou Hui ◽

Tian Hao-Yuan ◽

Cheng Wei ◽

...

Keyword(s):

Damage Mechanics ◽

Triaxial Compression ◽

Ct Scanning ◽

Confining Pressure ◽

Triaxial Tests ◽

Compression Tests ◽

Ct Number ◽

Confining Pressures ◽

Loading Tests ◽

Rock Specimens

Abstract Computed tomography (CT) scanning technology is helpful in investigating rock materials as it can demonstrate the micro structure of rock clearly. Conventional triaxial compression tests and the corresponding graded triaxial loading tests were carried out to investigate the complex failure mechanism of the marble at the Jinping Hydropower Station. After that CT-scanning tests were done on the loaded marble specimens. The test results show that (1) the CT numbers of the specimens have a certain statistical regularity, that is, the CT numbers of the specimens under different confining pressures satisfy the Weibull distribution, as the confining pressure increases, the mean values rise while variances decrease; (2) in the two groups of tests, the average CT numbers corresponding to the conventional triaxial tests are higher than those corresponding to the graded loading tests, but the CT number variances are lower than those of the graded loading tests; and (3) according to meso-damage mechanics, the damage variables of the rock specimens were established based on the definition of CT numbers. The calculation results show that the damage variables decrease with the increase in confining pressure, the damage variables of the rock specimens in the graded loading tests are higher than those in the conventional triaxial test, and the differences between the two loading tests have grown with the increase in confining pressure.

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Disturbance Evolution Behavior of Loess Soil under Triaxial Compression

Advances in Civil Engineering ◽

10.1155/2020/4160898 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Yali Xu ◽

Panpan Guo

Keyword(s):

Triaxial Compression ◽

Deformation Modulus ◽

Loess Soil ◽

Confining Pressure ◽

Compression Tests ◽

Structural Effects ◽

Moisture Contents ◽

Confining Pressures ◽

Evolution Behavior ◽

Disturbance Function

This paper presents an investigation into the evolution law of the structural effects of Xi’an loess soil, based on the disturbed state concept. First, a series of consolidated and drained triaxial compression tests were performed on undisturbed and remoulded loess samples prepared at five different moisture contents and tested at four different confining pressures. Second, two disturbance functions with different parameters were proposed to quantify mathematically the structural effects of loess. Finally, the proposed disturbance functions were validated against documented test results by other researchers. The results indicated that the single-parameter disturbance function, with the deformation modulus as its parameter, provides convenience for application but takes no account of the respective contributions of deviatoric stress and mean stress to the disturbance evolution behavior of loess. The double-parameter disturbance function, with the shear and bulk moduli as its parameters, is capable of distinguishing these respective contributions and reflects well the disturbance evolution behavior of loess under various moisture contents and confining pressures. The effects of moisture content and confining pressure on the parameters of the disturbance functions were found to be unsteady. The proposed disturbance functions lay the foundation for establishing a constitutive model for loess accounting for the structural effect.

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IMPACT OF WATER AND CO2 ON THE MECHANICAL PROPERTIES OF LOW PERMEABLE ROCKS

Tyumen State University Herald Physical and Mathematical Modeling Oil Gas Energy ◽

10.21684/2411-7978-2021-7-2-130-146 ◽

2021 ◽

Vol 7 (2) ◽

pp. 130-146

Author(s):

Anatolii A. KISLITSYN ◽

Nikita V. Lipatov

Keyword(s):

Mechanical Properties ◽

Triaxial Compression ◽

Confining Pressure ◽

Strength Properties ◽

Pore Fluid ◽

Co2 Injection ◽

Core Samples ◽

Different Temperatures ◽

Confining Pressures ◽

Temporary Decrease

This article features experiments on triaxial compression of low-permeable dolomite samples with different confining pressures (2-20 MPa), different pore fluids (dry air, water, CO2), and different temperatures (25-150 °C). The authors have studied the effect of confining pressure, pore fluid and temperature on the strength properties of the studied samples. The results show an increase in the strength with grwoing confining pressure. When the confining pressure increases from 2 to 20 MPa, the compressive strength increases from 86 to 370 MPa. Temperature has a significant effect on rock strength under low confining pressure conditions. With the increasing confining pressure reaching 15 MPa, increasing temperature has little effect on the strength of dolomite samples. Under an effective confining pressure of 5 MPa, the temperature weakening occurs on the dolomite specimens when the temperature exceeds 90 °C. During compression, liquid diffusion occurs in the specimens. Higher water viscosity can cause a temporary decrease in effective confining pressure, which can increase the strength of the rock. More prominent fractures are observed in the samples, and more fluid is injected under CO2 injection conditions, which may be useful for increasing the permeability of the geothermal reservoir. Two groups of experiments have been performed on the samples in this study: the first group of experiments investigated the effect of confining pressure on the fracture stress of core samples, without pore fluid injection; the second group of experiments investigated the effect of water or CO2 and temperature on the mechanical properties of core samples.

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Mechanical Properties of Grouted Crushed Coal with Different Grain Size Mixtures under Triaxial Compression

Advances in Civil Engineering ◽

10.1155/2018/9473947 ◽

2018 ◽

Vol 2018 ◽

pp. 1-13 ◽

Cited By ~ 4

Author(s):

Yuhao Jin ◽

Lijun Han ◽

Qingbin Meng ◽

Suresh Sanda ◽

Haizhi Zang ◽

...

Keyword(s):

Grain Size ◽

Triaxial Compression ◽

Confining Pressure ◽

Peak Strain ◽

Compression Tests ◽

Reinforcement Effect ◽

Confining Pressures ◽

Mechanical Behaviours ◽

Ultimate Failure ◽

Different Grain Size

To have a better understanding of the reinforcement effect on the crushed zone after grouting in coal mining extraction work, a self-designed grouting apparatus was used to study the effects of the grain size mixtures (distribution) and the stress state on the mechanical behaviours of grouted crushed coal specimens. From the various grouting tests, triaxial compression tests and scanning electron microscopy (SEM) observations of grouted specimens with different grain size mixtures, it was found that, for the same grain size mixture, the peak (σp) and residual (σr) strengths of the grouted specimens increased with an increase in confining pressure. It was found that the average slope values of the σp-σ3 curves for the grouted specimens with different grain size mixtures were all larger than those of the σr-σ3 curves. It was observed that the peak strain (εp) of the grouted specimens with different grain size mixtures increased overall with increasing confining pressure. For constant confining pressure, the peak and residual strengths both gradually increased approximately linearly as the grain size mixtures varied from small to large, but at higher confining pressures, the influence of the grain size mixture on the peak (or residual) strength increased. These mechanical behaviours of the grouted crushed coal specimens were strongly dependent on the variation in the grain size mixtures and in the confining pressure, which can be explained by the crack evolution process within the grouted specimen under triaxial compression, to a certain extent. Ultimate failure of the grouted specimen occurred just after propagation and coalescence of the cracks through the entire grouted specimen. Moreover, there were three major microscopic diffusion modes for the grouts flowing in most of the crushed coal specimens. Based on these test results, it was found that the reinforcement effect of the grouted specimen related to the splitting grouting mode (occurring in most of the large specimens) seems to be better than that of the penetrating (filling) grouting mode (in most of the small specimens).

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Prefabricated Structures Surface Marble Rheological Tests and Constitutive Model Analysis

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.419 ◽

2014 ◽

Vol 501-504 ◽

pp. 419-425

Author(s):

Qing Xu ◽

Jiang Da He ◽

Hong Qiang Xie ◽

Ming Li Xiao ◽

Jian Feng Liu

Keyword(s):

Mechanical Properties ◽

Rheological Properties ◽

Flow Rate ◽

Axial Stress ◽

Triaxial Compression ◽

Confining Pressure ◽

Rheological Parameters ◽

Structural Plane ◽

High Confining Pressure ◽

Confining Pressures

The mechanical properties of intact rock and rock containing structural plane are very different. From the diversion tunnel of Jinping deep rock site to retrieve the complete block of marble, after a high confining pressure triaxial compression simulation tectonic movements, the formation of structural plane, it represents the mechanical properties of the original rock. On the surface of the marble structure containing triaxial compression creep tests, the results showed: at low confining pressure, the weak marble surface as micro-damage accumulation, the emergence of non-uniform partial destruction, while at high confining pressure, creep curve better continuity and integrity; different confining pressures, marble initial rheology and stability both appear rheological phase, accelerated phase rheological obvious; different confining pressures, the same stage of the axial stress steady flow rate compared with the confining pressure increases, the axial steady state flow rate becomes smaller; marble under test showed the rheological properties, the use of Nishihara model can better demonstrate the rheological properties and determine the rheological parameters for other practical engineering reference.

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