• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.259-264
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• 2002

In this study the shear strengths of a poorly grad ed rock material(d/sub max/≤50.8mm, C/sub u/=1.86) were determined by large direct shear test and large triaxial test. The obtained stress-strain curves by the above large shear tests for the rock materials are similar to the loose sand's or normally consolidated clay's curve, in which the peak strength does not appear obviously. And for the uniformly graded rock material the shear strength by large direct shear test may be overestimated around 1.54∼1.70 times that of large triaxial test.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.281-288
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• 2000

In this study, we tried to determine failure criteria for joints of soft rock using ring shear test machine. The residual stress fellowing shear behavior was determined by the result of ring shear test and direct shear test. Ring shear test with the specimens which cover a large deformation range was adapted to measure a residual stress, and was possible to present the peak stress to present the peak stress to the residual stress at the same time. Residual stress is defined a minimal stress of specimens with a large displacement and the result of the peak residual stress is shown by a size of displacement volume. Therefore, the residual stress in soil was decided by shear stress of maximum shear stress - shear displacement(angle) based on the test result of a hyperbolic function ((equation omitted), a, b ＝ experimental constant). In this study, it was proved that the residual stress of rock joint can be determined by using of this method.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.25-34
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• 2009

Since the particle sizes of the coarse materials used in dam or harbor constructions are much larger than those of typical soils, it is desirable that large shear testing apparatuses are used when performing shear tests on the coarse materials to obtain as accurate results as possible. Two large-scale shear testing apparatuses, large direct shear testing apparatus and large triaxial shear testing apparatus, are commonly used. Currently in Korea, however, there have not been many cases in which shear tests were done using the large apparatus due to mainly difficulties in manufacturing, diffusing, and operating them. In present study, both large direct shear tests and large triaxial shear tests were performed on the coarse materials, which are used as dam fill materials, for 6 test cases in which particle sizes, specimen sizes, vertical pressure (confining pressure) conditions were little different, and then, the shear strength characteristics of the materials were compared with the two different shear tests. The test results showed that, by the Mohr-Coulomb failure criterion, overall the shear strength obtained by the large direct shear tests was larger than that by the large triaxial shear tests. Moreover, the shear strength under the normal stress of 1,000 kPa was about 10 to 70% larger for the large direct shear tests than for the large triaxial shear tests, revealing the larger differences in the coarse materials, compared to typical soils.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.35-41
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• 2000

Residual stress is defined as a minimum stress with a large displacement of specimens and the residual stress after peak shear stress appears with displacement volume but there is no provision to select the residual stress. In the previous study, residual stress was recorded when the change of shear load is small in the condition of the strain more than 15%. But, in this study, hyperbolic function((No Abstract.see full/text), b=experimental constant) of soil test is adapted to joint of rock and the propriety is investigated. In a landslide and landsliding of artificial slope, wedge failure of tunnel with a large displacement, tests are simulated from peak stress to residual stress for safety analysis. But now. direct shear stress and triaxial compressive tests are usually performed to find out characteristics of shear stress about joint. Although these tests get a small displacement, that data of peak stress and residual stress are used for safety analysis. In this study, we tried to determine failure criteria for joints of rock using ring shear test machine. The residual stress following shear behavior was determined by the result of ring shear test and direct shear test. In conclusion, after comparing the results of the two test, we found that cohesion(c) and internal friction angle(ø) of ring shear test are 30% and 22% respectively of those of the direct shear test.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.169-176
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• 2024

Purpose: In this paper, an experimental study was conducted to analyze the difference in shear strength caused by the problem of excluding coarse particles due to the size of the test specimen in the direct shear test. Method: A large-scale direct shear test was conducted on three weathered soils containing coarse aggregates with a maximum diameter of 50mm. In addition, a small-scale direct shear test was performed using a sample with a maximum diameter of 5 mm, excluding coarse aggregates. Result: In the case of the small-scale direct shear test, compared to the results of the large-scale direct shear test containing large particles, the internal friction angle was about 2.3% smaller, and there was no significant difference. In terms of cohesion, compared to the large-scale direct shear test, the small-scale direct shear test derived about 80.3% smaller value, showing a relatively large difference. Conclusion: In the large-scale direct shear test, it was analyzed that the coarse particles had a greater impact on the cohesion than the internal friction angle. Therefore, granite weathered clay containing coarse particles is judged to have the same shear strength as the cohesive force that is not affected by vertical stress. In this study, it was analyzed that the small-scale direct shear test, which excludes the coarse particles that are commonly used, provides results on the safety side by excluding the effect of coarse particles.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.5-14
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• 2008

Shear characteristics of quarry blasted rocks were compared using large scale direct shear tests and triaxial tests. For comparison purpose, similar test conditions were simulated as much as possible and three types of relative density (50%, 70%, 90%) were employed for the test. Results indicate that stress-strain behavior shows the same trend for two tests, but the measured shear strengths differ for the different test ms and depends on the relative density. At low relative density, the internal friction angles from direct shear test are smaller than those from triaxial tests. However, at high relative density, this phenomenon is reversed.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.590-596
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• 2019

Purpose: An experimental study was conducted on the sand samples for the size effect of the test specimens, one of the problems of the direct shear test. Method: Jumunjin standard sand, a representative sand of Korea, was used as sand sample. The large direct shear test was performed to analyze the shear strength at 50%, 60%, 70%, and 80% relative density, and then the comparative results were compared with the test results of the small direct shear test. Result: It was analyzed that the internal friction angle of the small shear tester tended to be relatively large in the dense region. It was analyzed that the results of the large shear tester tend to be relatively large in the region of medium relative density. Conclusion: The size effect on the samples in the direct shear test on sandy soil was analyzed to be relatively small.

• Steel and Composite Structures
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• v.36 no.1
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• pp.103-118
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• 2020

The static behavior of grouped large-headed studs (d = 30 mm) embedded in ultra-high performance concrete (UHPC) was investigated by conducting push-out tests and numerical analysis. In the push-out test, no splitting cracks were found in the UHPC slab, and the shank failure control the shear capacity, indicating the large-headed stud matches well with the mechanical properties of UHPC. Besides, it is found that the shear resistance of the stud embedded in UHPC is 11.4% higher than that embedded in normal strength concrete, indicating that the shear resistance was improved. Regarding the numerical analysis, the parametric study was conducted to investigate the influence of the concrete strength, aspect ratio of stud, stud diameter, and the spacing of stud in the direction of shear force on the shear performance of the large-headed stud. It is found that the stud diameter and stud spacing have an obvious influence on the shear resistance. Based on the test and numerical analysis results, a formula was established to predict the load-slip relationship. The comparison indicates that the predicted results agree well with the test results. To accurately predict the shear resistance of the stud embedded in UHPC, a design equation for shear strength is proposed. The ratio of the calculation results to the test results is 0.99.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.529-532
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• 1999

This paper presented the characteristics of shear strength of domestic municipal wastes including S landfill wastes. A series of large direct shear tests were peformed with waste specimens sampled from S landfill located in middle area of domestic land. Investigated items were cohesion and internal friction angle of shear strength parameter. The test result was compared with existing test data. The research results showed that cohesion 0.1296∼0.1340kg/$\textrm{cm}^2$ and angle of friction 22.1$^{\circ}$∼25.3$^{\circ}$for S landfill wastes, cohesion 0∼0.381kg/$\textrm{cm}^2$ and friction angle 22.1$^{\circ}$∼41.3$^{\circ}$ for domestic landfill wastes.

• Steel and Composite Structures
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• v.49 no.2
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• pp.197-213
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• 2023

To investigate the static properties of large high strength bolt shear connector in hybrid fiber-reinforced concrete (HFRC) and normal concrete (NC), eight push-out test specimens with single/double nut and HFRC/NC slabs were designed and push-out tests were conducted. A fine 3D nonlinear finite element (FE) model including HFRC constitutive model was established by using ANSYS 18.0, and the test results were used to verify FE models of the push-out test specimens. Then a total of 13 FE models were analyzed with various parameters including fiber volume fractions of HFRC, bolt diameter and thickness of steel flange. Finally, the empirical equations considering the contribution of polypropylene fiber (PF) and steel fiber (SF) obtained from the regression of the test results and FE analysis were recommended to evaluate the load-slip curve and ultimate capacity of the large high strength bolt shear connector embedded in HFRC/NC.