scholarly journals Triaxial Strength Criteria in Mohr Stress Space for Intact Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Baohua Guo ◽  
Long Wang ◽  
Yizhe Li ◽  
Yan Chen
Keyword(s):  
Tensile Strength ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Stress Space ◽  
Failure Envelope ◽  
Limit Values ◽  
Strength Criteria ◽  
Triaxial Strength ◽  
Failure Envelopes ◽  
Exponential Equations

Conventional triaxial strength criteria are important for the judgment of rock failure. Linear, parabolic, power, logarithmic, hyperbolic, and exponential equations were, respectively, established to fit the conventional triaxial compression test data for 19 types of rock specimens in the Mohr stress space. Then, a method for fitting the failure envelope to all common tangent points of each two adjacent Mohr’s circles (abbreviated as CTPAC) was proposed in the Mohr stress space. The regression accuracy of the linear equation is not as good as those of the nonlinear equations on the whole, and the regression uniaxial compression strength (σc)r, tensile strength (σt)r, cohesion cr, and internal frictional angle φr predicted by the regression linear failure envelopes with the method for fitting the CTPAC in the Mohr stress space are close to those predicted in the principal stress space. Therefore, the method for fitting CTPAC is feasible to determine the failure envelopes in the Mohr stress space. The logarithmic, hyperbolic, and exponential equations are recommended to obtain the failure envelope in the Mohr stress space when the data of tensile strength (σt)t are or are not included in regression owing to their higher R2, less positive x-intercepts, and more accurate regression cohesion cr. Furthermore, based on the shape and development trend of the nonlinear strength envelope, it is considered that when the normal stress is infinite, the total bearing capacity of rock tends to be a constant after gradual increase with decreasing rates. Thus, the hyperbolic equation and the exponential equation are more suitable to fit triaxial compression strength in a higher maximum confining pressure range because they have limit values. The conclusions can provide references for the selection of the triaxial strength criterion in practical geotechnical engineering.

EMPIRICAL STRENGTH ENVELOPE FOR SHALE

2016 ◽  
Vol 78 (7-3) ◽  
Author(s):  
Mohd For Mohd Amin ◽  
Nur‘Ain Mat Yusof ◽  
Rini Asnida Abdullah
Keyword(s):  
Failure Criterion ◽  
Sedimentary Rock ◽  
Triaxial Compression ◽  
Compression Tests ◽  
Failure Envelope ◽  
Rock Samples ◽  
Failure Envelopes ◽  
Project Site ◽  
Coulomb Criterion ◽  
Triaxial Compression Tests

Effectively, strength envelope describes behavior of rock when subjected to common stresses in construction, i.e. compressive, triaxial and tensile stresses. This study is aimed at investigating the strength envelope for shale, a sedimentary rock obtained from dam project site in Baram, Sarawak. Series of triaxial compression tests were carried out to obtain the strength envelope for the rock samples. For verification of failure criterion, uniaxial compression and Brazilian tests were also conducted on the rock samples. Results from the relevant tests were analysed using RocData software to obtain the strength envelope. Subsequently, Mohr-Coulomb and Hoek-Brown failure criterion are used to determine failure envelop for the rock samples. Based on the failure envelopes and the related strengths (i.e. compressive and tensile strength), suitability of both approach, in defining strength envelope for shale, is verified. The study shows that for highly laminated sedimentary rock like shale, Hoek-Brown criterion gave a more representative failure behaviour. The failure envelope clearly shown all the strength limits when the rock is subjected to triaxial, uniaxial and tensile stress, which is not clearly shown in the Mohr-Coulomb criterion. Therefore, Hoek-Brown criterion is a more appropriate method for describing strength envelope, as it able to show the limiting stresses when rock samples are subjected to common stresses in construction.

scholarly journals Properties and Structure of Concretes Doped with Production Waste of Thermoplastic Elastomers from the Production of Car Floor Mats

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 872
Author(s):  
Malgorzata Ulewicz ◽  
Alina Pietrzak
Keyword(s):  
Tensile Strength ◽  
Production Process ◽  
Compression Strength ◽  
Physical And Mechanical Properties ◽  
Thermoplastic Elastomer ◽  
Thermoplastic Elastomers ◽  
Production Waste ◽  
Fine Aggregate ◽  
Freezing And Thawing ◽  
Average Decrease

This article presents physical and mechanical properties of concrete composites that include waste thermoplastic elastomer (TPE) from the production process of car floor mats. Waste elastomer (2–8 mm fraction) was used as a substitute for fine aggregate in quantities of 2.5, 5.0, 7.5, and 10% of the cement weight. For all series of concrete, the following tests were carried out: compression strength, bending tensile strength, splitting tensile strength, absorbability, density, resistance to water penetration under pressure, frost resistance, and abrasion resistance, according to applicable standards. Moreover, SEM/EDS analysis was carried out on the surface microstructure of synthesized concrete composites. It was proven that the use of production waste from the production process of car floor mats in the quantity of 2.5% does not influence the change of the concrete microstructure and it does not result in the decrease of the mechanical parameters of concrete modified with waste. All concrete modified with the addition of waste meet standards requirements after carrying out 15 cycles of freezing and thawing, and the average decrease in compression strength did not exceed 20%. Adding waste in the quantity of 2.5% allows for limiting the use of aggregate by about 5%, which is beneficial for the natural environment.

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.

Behaviour and simulation of sedimentary rocks

1967 ◽  
Vol 2 (4) ◽  
pp. 307-316 ◽  
Author(s):  
D W Hobbs
Keyword(s):  
Tensile Strength ◽  
Elastic Properties ◽  
Triaxial Compression ◽  
Sedimentary Rocks ◽  
Model Material ◽  
Scale Model ◽  
Dimensionless Analysis

Investigations on the elastic properties and strength of sedimentary rocks in uniaxial and triaxial compression and on the tensile strength of sedimentary rocks are described. A brief account is given of the application of dimensionless analysis to scale-model roadway tests and of the properties of a scale-model material.

Ultimate Tensile Properties of Elastomers. II. Comparison of Failure Envelopes for Unfilled Vulcanizates

1964 ◽  
Vol 37 (4) ◽  
pp. 792-807 ◽  
Author(s):  
Thor L. Smith
Keyword(s):  
Natural Rubber ◽  
Elevated Temperatures ◽  
Cross Sectional Area ◽  
Chemical Degradation ◽  
Sectional Area ◽  
Failure Envelope ◽  
Cross Sectional ◽  
Failure Envelopes ◽  
The Moment ◽  
Styrene Butadiene

Abstract The tensile stress-at-break σb (based on the initial cross-sectional area) and the corresponding ultimate extension ratio λb of unfilled vulcanizates of silicone, hydrofluorocarbon (Viton B), butyl (both sulfur-cured and resin-cured), and natural rubber were determined at many strain rates and temperatures; the latter ranged from slightly above the glass transition temperature Tg, up to a temperature somewhat below that at which chemical degradation affected the results. For each vulcanizate except natural rubber, data obtained over an extended temperature range superposed to give a time- and temperature-independent failure envelope on a plot of log (σb273/T) vs log (λb−1), where T is the test temperature in °K; for natural rubber, data obtained between 90° and 120° C superposed, but those at lower temperatures did not because of strain-induced crystallization. For each vulcanizate, data at elevated temperatures gave, or tended toward, a line of unit slope on a plot of log (λbσb273/T) vs log (λb−1), where λbσb is the breaking stress based on the cross-sectional area at the moment of rupture. The position of each line corresponded to the equilibrium modulus Ee derived from stress-strain curves. Failure envelopes previously obtained for two styrene—butadiene vulcanizates, which had different crosslink densities, superposed to give a master failure envelope on a plot of log (λbσb273/T) vs logEe(λb−1). On this type of plot, failure envelopes for all the vulcanizates except silicone and natural rubber were found to be essentially identical. At a given value of λbσb, silicone had a smaller λbλb and natural rubber a somewhat larger λbλb than the vulcanizates of the three other rubbery polymers.

The Study on Mechanical Properties of POSS Hybrid PVA Hydrogels

2014 ◽  
Vol 1022 ◽  
pp. 30-33
Author(s):  
Yi Chen ◽  
Jun Hong Yang ◽  
Wen Yong Liu ◽  
Guang Sheng Zeng
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compression Strength ◽  
Water Soluble ◽  
Polymer Chains ◽  
Hybrid Nanocomposite ◽  
Nanocomposite Hydrogels

A novel POSS hybrid nanocomposite hydrogels were synthesized by introducing water-soluble Oa-POSS into the PVA hydrogels. The mechanical properties are obviously dependent on the composition of gels. With the increase of Oa-POSS, the tensile strength and modulus increases significantly while the elongation break decreases. The gels exhibit higher compression strength than pure PVA hydrogels. This phenomenon is attributed to the effective entanglement of polymer chains around nanoparticles and enhanced interaction between PVA chains.

A strain-based tensor polynomial failure criterion for anisotropic materials

1988 ◽  
Vol 23 (4) ◽  
pp. 179-186 ◽  
Author(s):  
W Zhang ◽  
K E Evans
Keyword(s):  
Epoxy Resin ◽  
Plane Stress ◽  
Failure Criterion ◽  
Maximum Stress ◽  
Failure Criteria ◽  
Anisotropic Materials ◽  
Maximum Strain ◽  
Stress Space ◽  
Failure Envelope ◽  
Stress Maximum

A strain-based tensor polynomial failure criterion for anisotropic materials is proposed with explicit derivations given in both strain and stress space. The physical distinction between this strain-based criterion and the current stress-based tensorial criterion of Tsai and Wu, is clarified. The viability of the proposed criterion is shown by its application to a graphite—epoxy resin lamina under plane stress. The allowed loadings and failure envelope of this lamina are predicted. Comparison is made with existing failure criteria (both stress-based and strain-based), in particular the maximum stress, maximum strain, and Tsai-Wu criteria.

On New Modifications of Some Strength Criteria for Anisotropic Materials

2016 ◽  
Vol 724 ◽  
pp. 53-57 ◽  
Author(s):  
S.L. Shambina ◽  
F.V. Rekach ◽  
Y.V. Belousov
Keyword(s):  
Limit State ◽  
Strength Criterion ◽  
Material Strength ◽  
Small Element ◽  
Exact Results ◽  
Strength Condition ◽  
Stress Space ◽  
Strength Criteria ◽  
State Of Stress ◽  
The Moment

The strength criterion is the strength condition for a small element of the construction’s material. Strength criterion is analytical interpretation in stress space the allowable boundaries of stress state, within these boundaries the material can work under these conditions without breaking. Since analytical interpretation of the experimental data may be performed in different ways, therefore many different strength criteria exist. Properly chosen strength criterion allows determining the moment when the material is destroyed while it is working under various tense conditions. Also it gives an opportunity to assess the limit state of stress in the most loaded points of the structure. This paper suggests new modifications of some well-known strength criteria which are more comfortable for practical use and can help to achieve more exact results.

Seafloor Polymetallic Sulfides Mechanical Property Test

2014 ◽  
Vol 1015 ◽  
pp. 316-319
Author(s):  
Zhong Hua Huang ◽  
Shao Jun Liu ◽  
Ying Guang Xu ◽  
Wang Hu
Keyword(s):  
Compressive Strength ◽  
Internal Friction ◽  
Uniaxial Compressive Strength ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Method ◽  
Dry Density ◽  
Average Value

Seafloor polymetallic sulfide specimens were developed according to engineering rock test method standard (GB/T 50266-2013). Seafloor polymetallic sulfide wet density and dry density were tested. Uniaxial compressive strength and triaxial compression strength of seafloor polymetallic sulfide were tested using rock mechanics test system MTS 815. Elasticity modulus and Poisson's ratio of seafloor polymetallic sulfide were calculated based on specimens stress-strain curves. Cohesion and internal friction angle were calculated based on specimens triaxial test Mohr stress circle. Test results show that seafloor polymetallic sulfide dry density average value is 2.6 g/cm3, wet density average value is 2.94 g/cm3. Uniaxial compressive strength and triaxial compression strength of seafloor polymetallic sulfide are unstable. Average value of the uniaxial compressive strength is 10.243MPa. Average value of triaxial compression strength test peak load is 47.166KN. Cohesion is 2.447MPa and internal friction angle is 38.04o.

Sign in / Sign up

Export Citation Format

Share Document