Determination of the friction angle of soils in triaxial-compression apparatus and shear devices

1985 ◽  
Vol 22 (3) ◽  
pp. 105-111
Author(s):  
A. L. Kryzhanovskii ◽  
Yu. S. Vil'gel'm ◽  
S. V. Medvedev
Keyword(s):  
Triaxial Compression ◽  
Friction Angle

scholarly journals Numerical Experiments on Triaxial Compression Strength of Soil-Rock Mixture

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yanxi Zhao ◽  
Zhongxian Liu
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Data Statistics ◽  
Nonlinear Hardening ◽  
Properties Of Soil

Soil-rock mixture is a kind of unfavorable geologic material, and it is composed of low-strength soil particles and high-stiffness rock blocks. Mechanical properties of soil-rock mixture were controlled by the internal mesoscopic medium, thus resulting in great difficulties of determination of mechanical parameters. In this paper, influences of rock content, mesoscopic features, and random distribution of mixture in soil-rock mixture on its shear strength were discussed through discrete element numerical simulation of the laboratory triaxial test. Results demonstrated that, with the increase of rock content, the internal friction angle of soil-rock mixture increased continuously, while the cohesion of soil-rock mixture decreased firstly and then increased. The stress-strain curve belonged to a nonlinear hardening type, which was close to soil characteristic. However, the shear strength was affected by mesoscopic medium of mixture particles significantly, resulting in the strong discreteness of strength, and only by large amounts of data statistics can we get a better regularity of strength. The research results can provide references to determine mechanical parameters of soil-rock mixture.

scholarly journals LABORATORY INVESTIGATION ON THE CORRELATION BETWEEN THE FRICTION ANGLE OF ROCK JOINTS AND THE CONSTANT MI OF THE HOEK AND BROWN CRITERION

2017 ◽  
Vol 50 (2) ◽  
pp. 987
Author(s):  
A. Tsikrikis ◽  
T. Papaliangas ◽  
V. Marinos
Keyword(s):  
Triaxial Compression ◽  
Rock Fracture ◽  
Rock Joint ◽  
Friction Angle ◽  
Intact Rock ◽  
Rock Joints ◽  
Direct Shear ◽  
Compression Tests ◽  
Rock Types

A correlation between the non-dilational friction angle (φm) of rock discontinuities and the constant mi of the Hoek and Brown criterion for intact rock is investigated, using the results of a focus oriented laboratory program. The program consisted of two types of laboratory tests: a series of triaxial compression tests on intact rock samples for the determination of the constant mi and an independent series of direct shear tests on tensile fractures of the same rock types for the determination of the rock joint friction angle φm. Four typical rock types from Northern Greece were used: a granite, a sandstone, a limestone and a marble, covering a range of mi between 8 and 34, and an unconfined compressive strength between 60 and 120 MPa. Apart from the certain range of parameters that is presented for this specific rocks, the experimental results show that the non-dilational friction angle of the rock fracture determined by direct shear testing (φm) decreases logarithmically with the value of the constant mi.

scholarly journals Field and Laboratory-based Approach for the Determination of Friction Angle of Geological Discontinuities of Malaysian Granites

2011 ◽  
Vol 28 (2) ◽  
pp. 151 ◽  
Author(s):  
R. A Ghani ◽  
T. L Goh ◽  
A. M Hariri ◽  
Y. N Baizura
Keyword(s):  
Friction Angle ◽  
Roughness Coefficient ◽  
Average Value ◽  
Peak Friction Angle ◽  
Maximum Value ◽  
Wide Range ◽  
Discontinuity Surfaces ◽  
Geological Discontinuities ◽  
Range Of Values

The basic friction angle, Φb for artificially sawn discontinuity planes for fresh granite, as determined by tilt testing, has an average value of 30º. For the natural rough discontinuity surfaces, a wide range of values have been determined for the peak friction angle, Φpeak ranging from 47º to a maximum value of 80º, depending on the joint roughness coefficient (JRC). The average values of the friction angles for the different degrees of roughness were as follows: JRC 2–4 = 58°; JRC 6–8 = 60°; JRC 8–10 = 47°; JRC 12–14 = 60°; JRC 14–16 = 71° ; JRC 18–20 = 80°.

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 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.

Ecological Highway Slope Stability Analysis by Inversion Method

2011 ◽  
Vol 250-253 ◽  
pp. 2161-2166
Author(s):  
Jun Zhao Gao ◽  
Guo Feng Xiao ◽  
Hai Qiang Miao
Keyword(s):  
Slope Stability ◽  
Soil Mechanics ◽  
Friction Angle ◽  
Inversion Method ◽  
Time Inversion ◽  
Long Time ◽  
Main Factors ◽  
Reinforcement Design ◽  
Rock And Soil

Side slop losing stability is one of the main factors which greatly influences freeway expedite construction, especially after side slop losing stability the determination of rock and soil mechanics parameter may take a long time. Inversion method to analyze slope stability can preferably solve the problem. During the treatment of the ecological freeway landslide, we can not obtain important Parameters due to great disparity of sample Parameters of landslide. However, using inversion method to get cohesion and internal friction Angle, and anglicizing its sensitivity during calculation of stability can identify reliable Parameters. According to slope stability calculus, the ecological reinforcement design scheme come into effect.

scholarly journals Sensitivity Analysis in the Estimation of Mechanical Parameters of Engineering Rock Mass Based on the Hoek–Brown Criterion

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Zhiqiang Li ◽  
Guofeng Liu ◽  
Shuqian Duan ◽  
Shufeng Pei ◽  
Changgen Yan
Keyword(s):  
Rock Mass ◽  
Triaxial Compression ◽  
Damage Zone ◽  
Surrounding Rock ◽  
Geological Strength Index ◽  
Sensitivity Factor ◽  
Mechanical Parameters ◽  
Compression Tests ◽  
Disturbance Factor

Geological strength index GSI, disturbance factor (D), material constant mi, and uniaxial compressive strength σci of the intact rock are essential input parameters IPs of the Hoek–Brown H−B criterion. Mechanical parameters MPs of the engineering rock mass, including elastic modulus E, cohesion c, and internal friction angle φ estimated by the H–B criterion, and the predicted excavation response of surrounding rock, including the displacement and excavation damage zone EDZ based on the MPs, are of high relevance with the four IPs of the H–B criterion. In this paper, the deep and huge underground cavern excavated in basalt from a hydropower station under construction in the southwest of China is used to analyse the sensitivity of the IPs on the MPs, the displacement, and EDZ of the surrounding rock mass. Firstly, the H–B criterion is applied to estimate the MPs, among which the IPs are obtained from a series of in situ and laboratory tests, including borehole camera observation, wave velocity test, uniaxial and triaxial compression tests, and so on. Secondly, the sensitivity relationships between IPs, MPs, and prediction results of displacement and EDZ are established and described quantitatively by the sensitivity factor (si). Results show that the MPs of the rock mass are more sensitive to GSI and D⋅GSI and σci are high-sensitivity parameters affecting the displacement and EDZ. Finally, the variations in the estimated MPs and associated prediction results concerning excavation response, which are caused by the uncertainties in the determination of the IPs, are further quantified. This study provides a straightforward assessment for the variability of the rock mass parameters estimated by the H–B criterion. It also gives a valuable reference to similar geotechnical engineering for the determination of rock mass parameters in the preliminary design.

scholarly journals Confidence and Accuracy in Determination of the Critical State Friction Angle

2009 ◽  
Vol 49 (3) ◽  
pp. 391-395 ◽  
Author(s):  
Mohsen Ghafghazi ◽  
Dawn Shuttle
Keyword(s):  
Critical State ◽  
Friction Angle
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