scholarly journals Evaluation of the Impact of Hydrostatic Pressure and Lode Angle on the Strength of the Rock Mass Based on the Hoek–Brown Criterion

2015 ◽  
Vol 37 (2) ◽  
pp. 85-91
Author(s):  
Halina Marczak
Keyword(s):  
Rock Mass ◽  
Hydrostatic Pressure ◽  
Friction Angle ◽  
Stress Path ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Minimum Principal Stress ◽  
Lode Angle ◽  
The Impact

Abstract Determination of the global uniaxial compressive strength of rock mass on the basis of the Hoek-Brown failure criterion requires knowledge of the strength parameters: cohesion and the angle of internal friction. In the conventional method for the determination of these parameters given by Balmer, they are expressed by the minimum principal stress. Thus, this method does not allow for the assessment of an impact of hydrostatic pressure and stress path on the value of cohesion, friction angle and global uniaxial compression of rock mass. This problem can be eliminated by using the Hoek-Brown criterion expressed by the invariants of the stress state. The influence of hydrostatic pressure and the Lode angle on the strength parameters of the rock mass was analysed.

scholarly journals Determination of Equivalent Mohr-Coulomb Criterion from Generalised Hoek-Brown Criterion

2021 ◽  
Author(s):  
Qingqing Yang ◽  
Fei Cai
Keyword(s):  
Principal Stress ◽  
Least Squares Method ◽  
Method Comparison ◽  
Friction Angle ◽  
Engineering Practice ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Coulomb Criterion ◽  
Minor Principal Stress

Abstract A new analytical solution is presented for determining equivalent Mohr-Coulomb (MC) shear strength parameters over an arbitrary interval of minor principal stress σ3 from the generalised Hoek-Brown (HB) criterion using least squares method. Comparison with several published examples demonstrates that the proposed solution had a capacity to accurately determine equivalent MC parameters over a given interval of σ3, as well as instantaneous MC parameters by using a very small interval of σ3. EMC parameters depended heavily on the interval of σ3, which highlighted the importance of intervals of σ3. A calculation case shows that the equivalent internal friction angle and cohesion over the interval of σ3 from tension cut-off σcut−off to maximum minor principal stress σ3max were approximately 12% smaller and 10.3% larger than those over an interval from tensile strength to σ3max, respectively. The proposed solution offers great flexibility for the application of the HB criterion with existing methods based on the MC criterion for rock engineering practice.

scholarly journals The Influence of Compaction and Water Conditions on Shear Strength and Friction Resistance between Geotextiles and Ash-Slag Mixture

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1086
Author(s):  
Andrzej Gruchot ◽  
Tymoteusz Zydroń ◽  
Agata Michalska
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Saturation ◽  
Friction Angle ◽  
Interaction Coefficient ◽  
Interfacial Friction ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Friction Resistance

The paper presents the results of tests of the shear strength of the ash–slag mixture taken from the landfill located in Kraków (Poland) and the interfacial friction resistance at the contact between the ash–slag mixture and woven or nonwoven geotextiles. The tests were carried out in a direct shear apparatus on samples with and without water saturation. The samples for testing were formed in the apparatus box at the optimum moisture by compacting them to IS = 0.90 and 1.00. The test results reveal that the shear strength parameters of the ash-slag mixture were large. It was stated the significant influence of the compaction, the growth of which has resulted in an increase in the angle of internal friction (from 7% to 9%) and cohesion (from 60% to 97%). Whereas the saturation of the samples reduced the shear strength parameters (from 4% to 6%, of the internal friction angle and 30% to 43% of cohesion). The values of the interfacial friction resistance at the contact between the ash–slag mixture and the geotextiles were large as well, but slightly smaller than the values of the shear strength parameters of the mixture itself. The compaction caused an increase in the angle of interfacial friction (from 1% to 5%) and adhesion (from 31% to 127%). The water-saturation of the samples caused a change in the angle of interfacial friction (from −6% to 3%) and decline in the adhesion (from 22% to 69%). Values of the interaction coefficient were about 0.8–1.0 and they tended to rise with increasing the normal stress. Higher values of this parameter were obtained in tests with water saturation and for non-woven geotextiles.

Gross Error Elimination and Index Determination of Shearing Strength Parameters in Triaxial Test

2013 ◽  
Vol 353-356 ◽  
pp. 152-158
Author(s):  
Fang Wei
Keyword(s):  
Nonlinear Programming ◽  
Solution Process ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Strength Parameters ◽  
Gross Error ◽  
Error Elimination ◽  
Shearing Strength ◽  
Programming Solution

In order to determine shearing strength parameters of triaxial tests(cohesion and friction angle), nonlinear programming solution was suggested based on “minimum square sum of distance”. After proving that the vertical distances between Mohr circles and the regressed strength line are distributed normally, data with gross error would be excluded; moreover, the only strength line, as well as cohesion and friction angle, could be determined. Combining with Matlab, the solution process became rapid, precise and intuitive. Some examples verified the applicability of suggested method finally.

scholarly journals SOIL SHEARING EQUIPMENT AND ACCURACY OF INVESTIGATION RESULTS

1998 ◽  
Vol 4 (2) ◽  
pp. 129-133
Author(s):  
Antanas Alikonis
Keyword(s):  
Soil Structure ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Undisturbed Soil ◽  
Angle Of Internal Friction ◽  
Soil Stress ◽  
Soil Shear Strength ◽  
The Usa ◽  
Constant Shear Rate

Civil engineering works require strength and stability. Soil subbase strength parameters, ie cohesion and the angle of internal friction are used in calculations. They are experimentally determined parameters. Determination of soil strength parameters by shearbox apparatus is being legalised by standards and used along with triaxial equipment in the USA, England, Austria, Russia, Lithuania and many other countries. Accuracy of investigation results depends on the construction of soil shearing apparatus. Soil stress on shearing plane should be registrated during the test, undisturbed soil structure should be preserved before shearing is started, friction between soil and parts of shearing apparatus should be avoided and constant shear rate assured during the whole test. Schemes of shearing apparatus presented in literature and standards show their inability of avoiding all the conditions mentioned above. The report presents ways of improving soil shearing equipment, which leads to a more precise investigation of soil shear strength parameters.

scholarly journals Changes in the Strength Characteristics of Glinistx Soils under the Influence of Dynamic Forces

2020 ◽  
Vol 9 (5) ◽  
pp. 639-643
Keyword(s):  
Internal Friction ◽  
Experimental Studies ◽  
Sharp Decrease ◽  
Friction Angle ◽  
Strength Characteristics ◽  
Clay Soils ◽  
Angle Of Internal Friction ◽  
Dynamic Forces ◽  
The Impact ◽  
Soil Indicators

In order to study in depth the impact of vibration on the strength characteristics of clay soils, as well as to develop methods that increase the strength characteristics and contribute to the elimination of seismic shrinkage deformations of clay soils, we conducted research in the field. In field experimental studies, the svaw-12 trailed, smooth vibration roller, manufactured in Germany, was used. We paid special attention to the further behavior of the soil after the vibration and made observations and measurements of soil indicators for two months. The experiments in the field with vibration column showed an increase of soil deformation with increasing duration of the fluctuations, i.e. there is a linear relationship between the increases in soil density on the duration of oscillations. In the process of vibration, there is a sharp decrease in the force of adhesion and the angle of internal friction, which is apparently associated with a violation of the structure of the soil and its compaction. And then at the end of the vibration process, over time, there is an increase in the adhesion (1.5-2 times) and the internal friction angle (1.2 times) of the soil, obviously as a result of the soil acquiring new strength and compaction under the influence of its own weight. This circumstance is also associated with the humidity state of the soil.

scholarly journals Determination of Mohr–Coulomb Parameters from Nonlinear Strength Criteria for 3D Slopes

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Di Wu ◽  
Yuke Wang ◽  
Yue Qiu ◽  
Juan Zhang ◽  
Yukuai Wan
Keyword(s):  
Optimization Procedure ◽  
Strength Criterion ◽  
Friction Angle ◽  
Strength Parameters ◽  
Strength Criteria ◽  
Engineering Standards ◽  
3D Effects ◽  
Software Codes ◽  
The Stability

Many experimental data have illustrated that the strength envelops for soils are not linear. Nevertheless, the linear Mohr–Coulomb (MC) strength parameters are widely applied for the conventional method, software codes, and engineering standards in the slope design practice. Hence, this paper developed the 3D limit analysis for the stability of soil slopes with the nonlinear strength criterion. Based on a numerical optimization procedure written in Matlab software codes, the equivalent MC parameters (the equivalent friction angle and the equivalent cohesion) from the nonlinear strength envelopes were derived with respect to the least upper-bound solutions. Further investigations were made to assess the influences of nonlinear strength parameters and slope geometries on the equivalent MC parameters. The presented results indicate that the equivalent MC parameters are closely related to the nonlinear strength parameters. As the inclination angle increases, the equivalent friction angle becomes bigger, but the equivalent cohesion becomes smaller. Besides, 3D effects on the equivalent MC parameters were found to be slight. The presented approach for the determination of MC strength parameters is analytical and rigorous, and the approximate MC strength parameters in the provided design tables can be alternative references for practical use.

In situ determination of a rock mass modulus using a high resolution tiltmeter

1996 ◽  
Vol 33 (2) ◽  
pp. 350-355 ◽  
Author(s):  
Bassam Saleh ◽  
Abdallah I Husein Malkawi ◽  
Pierre A Blum
Keyword(s):  
Rock Mass ◽  
High Resolution ◽  
Boussinesq Model ◽  
New Approach ◽  
Structural Work ◽  
Rock Mass Modulus ◽  
Elastic Rock ◽  
The Impact

A very high resolution tiltmeter (10–8 rad, 0.002 s) developed by P.A. Blum, in 1957 was used to establish a new approach to directly evaluate the in situ average elastic rock-mass modulus. Five tiltmeters were installed on the facades of the Louvre museum to study the deformations induced by internal structural work and by the impact of the Paris metro traffic movement. The measured data from the tiltmeter were used to determine the elastic rock modulus of the museum's foundation using the Boussinesq model. The results obtained by the developed approach are consistent with the typical elastic rock-mass modulus for the rock found in the museum's foundations. Key words: rock-mass modulus, tiltmeter, deformation, Boussinesq model.

scholarly journals Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

2020 ◽  
Vol 8 (9) ◽  
pp. 634
Author(s):  
Yang Wu ◽  
Xing Wang ◽  
Jian-Hua Shen ◽  
Jie Cui ◽  
Chang-Qi Zhu ◽  
...  
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Particle Breakage ◽  
Internal Friction Angle ◽  
Capillary Water ◽  
Strength Parameters ◽  
Apparent Cohesion ◽  
The Impact

The effect of capillary water caused by heavy rainfall and groundwater level fluctuations can induce the erosion and collapse of island reef coral sand foundations. Here, the effects of water content (ω) on the shear strength parameters of coral gravelly sand are analyzed at the macro and micro scales by laboratory consolidated-drained triaxial compression and nuclear magnetic resonance tests. Furthermore, particle breakage characteristics of coral gravelly sand under the static load are discussed. With increasing ω, (1) the internal friction angle increases slightly (<1°) then decreases; (2) the apparent cohesion is more sensitive to the change in the ω; (3) with an increase from 5.4% to 21.3%, the bound water content remains almost unchanged; (4) the capillary water content is the main factor impacting the apparent cohesion; (5) the increase in free water content is the internal cause of the decreasing internal friction angle of coral gravelly sand with ω > 11.1%; and (6) the particle breakage increases, and there is an approximately linear relationship between the median particle diameter (d50) and relative breakage index (Br). The established physical model can reflect the influence of water content and plastic work and describe the evolution law of particle breakage.

scholarly journals New Method for Determination of Residual Strength Parameters and Critical Damage Value

2019 ◽  
Author(s):  
Qiao Jiang ◽  
Jianlin Li ◽  
Yanhai Wang ◽  
Zuosen Luo ◽  
Tao Li ◽  
...  
Keyword(s):  
Residual Strength ◽  
Confining Pressure ◽  
Stress Path ◽  
Load Test ◽  
Repeated Loading ◽  
Strength Parameters ◽  
Loading Test ◽  
Time Saving ◽  
Critical Damage

Residual strength and critical damage parameters are worthy to evaluate the stability of engineered rock masses. In this paper, new thinking, repeated load test on a single specimen was proposed to measure the residual strength of the rock. And author proposed to modify the critical damage value based on residual constitutive energy. The test results showed that: (1) the residual strength of rock is mainly controlled by the confining pressure, without a clear relationship with the confining pressure and stress path of the initial loading failure. (2) The residual strength parameters of the rock specimens under repeated loading test are consistent with the conventional triaxial test. Most importantly, the proposed method is relatively less dispersion, cheap, reliable, and time-saving. (3) The corrected critical damage value was reasonable. Relevant test methods can provide a useful reference for the determination of residual strength parameters and critical damage value.

Determination of the Strength Parameters of Pinewood Based on the Non-Destructive Sclerometric Test with a Wood Hammer

2020 ◽  
Vol 30 (1) ◽  
pp. 43-52
Author(s):  
Bartosz Szostak ◽  
Maciej Trochonowicz ◽  
Mateusz Kowalczyk
Keyword(s):  
Compressive Strength ◽  
Nondestructive Testing ◽  
Technical Condition ◽  
Strength Parameters ◽  
The Impact ◽  
Non Destructive ◽  
Structure And Design

AbstractTo assess the technical condition of a structure and design it using existing elements, it is necessary to know its parameters. For existing facilities, it is often not possible to get a sample of material and examine it directly in the laboratory. For this reason, in situ nondestructive testing is very important.The main goal of the paper is to present the issues related to determining the strength parameters of a particular wood based on the non-destructive sclerometric test performed with a wood sclerometric hammer. The study also presents the results of the impact of pinewood density on its compressive strength.

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