• The Journal of Engineering Geology
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• v.21 no.4
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• pp.361-367
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• 2011

The uniaxial compressive strength (UCS) is an important factor in the design and construction of surface and underground structures. However, the method employed to measure UCS is time consuming and expensive to apply in the field. Therefore, we developed a model to estimate UCS based on a few properties using linear regression analysis, which is a statistical method. To develop the model, valid factors from the test results were selected from a correlation analysis using a statistical program, and the model was formulated by linear regression based on the relationships among factors. UCS estimates derived from the model were compared with the results of UCS tests, to assess the reliability of the model. The relationship between rock properties and UCS indicates that the factors with the greatest influence on UCS are point load strength and shape facto r. The UCS values obtained using the model are in good agreement with the results of the UCS test. Therefore, the developed model may be used to estimate the UCS of rocks in regions with similar conditions to those of the present study area.

• Journal of the Korean GEO-environmental Society
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• v.7 no.2
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• pp.33-42
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• 2006

Eighteen biotite granites on Andong area and twenty seven igneous rocks(diorite, granite, andesite, rhyolite) on Yeosu area were tested to evaluate the correlations between the uniaxial compressive strength values, as determined by the standard uniaxial compression test, and the corresponding results of the ultrasonic velocity. The variability of test results for each test was evaluated by calculating the coefficient of determination or variation. Results indicate that strong correlations exist between the results of uniaxial compression vs the point load, Schmidt hammer and ultrasonic velocity test. The correlation equations for predicting compressive strength using different methods are presented along with their confidence limits. Ultrasonic velocity test used provide reliable estimates of compressive strength.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.72-96
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• 2018

Accurate estimation of the uniaxial compressive strength of rock is very crucial for the safety of construction activities occurring in the rock mass. However, the uniaxial compressive strength test is expensive and time consuming. Moreover, the uniaxial compressive strength test cannot be performed in the field. In order to solve this kind of problem, many foreign researchers investigated the use of the point load strength test for the estimation of uniaxial compressive strength of rock. However, the result of research obtained for rocks from other countries may not be directly applicable for rocks in Korea. The correlation between the point load strength index and the uniaxial compressive strength for rocks in Korea is suggested in the form of table by using the results of the extensive literature reviews and laboratory tests. The suggested result is expected to be used for the simple and quick estimation of uniaxial compressive strength of rocks in Korea.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.4 s.19
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• pp.29-36
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• 2005

In this study, relations among unconfined compressive strength, strain at maximum strength and depth were compared with each other. Test specimen is marine clay originated from the place near Ga-duck island in Busan city. In addition, influence of impure material contained in specimen and that of total core recovery(TCR) on unconfined compressive strength and degree of disturbance were investigated. As a result of tests, unconfined compressive strength decreases as strain corresponding to maximum strength increases. Also, the deeper the sampling depth and the bigger the TCR, the unconfined compressive strength increases. Especially, as the TCR increases, the unconfined compressive strength Increases and quality of specimen is enhanced.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.53-58
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• 2014

The uniaxial compressive strength and Young's modulus of intact rocks are the most important analytical parameters for design of rock mass structures. But the preparation of the samples for uniaxial compressive test is a hard and time consuming task. By using ultrasonic test, engineers can predict the analytical parameters that is the uniaxial compressive strength and Young's modulus. The uniaxial compressive test and ultrasonic test were carried out 115 samples of igneous rocks, 74 samples of metamorphic rocks and 55 samples of sedimentary rocks and, after regression analysis of the test results, best fit equations for predicting the uniaxial compressive strength and Young's modulus are proposed. In order to obtain a better correlations coefficient between uniaxial compressive strength and P-wave velocity, the P-wave velocity were multiplied by density values. The proposed equations for predicting uniaxial compressive strength and Young's modulus using ultrasonic test provide reliable results.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.215-225
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• 2008

In order to investigate the influence factors to compressive and tensile strength of basalt in Cheju Island, rock samples of Pyosenri basalt, trachy-basalt and scoria were taken from Seoguipo-Si Seongsan-Eup area, and a series of uniaxial compressive strength test and Brazilian test were carried out. Especially, these tests were performed in consideration of the loading speed, the moisture content in rock sample, and the anisotropy of rock strength. The uniaxial compressive strength was increased gradually as the loading speed rose. The increasing quantity of uniaxial compressive strength had a difference in each rock types. Also, the strength was decreased with increasing the moisture contents in rock sample by pore water. As the result of test considering the anisotropy of rock strength, the compressive strength in condition of failure occurred parallel to stratified layer is decreased about 12-26% more than that in condition of failure occurred inclined to stratified layer.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.5-9
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• 2013

In this study, it was examined a strength characteristic of organic acid material that is eco-friendly and low energy as a soil improving material. The object of this study is to analysis of strength changes with observing the clay mixed organic acid material through the unconfined compression strength test and triaxial compression test during 28 days. As a result of the tests, the strength of clay mixed organic acid material is increased when the more ages are prolonged, the more organic acid material mixture ratio growed. Therefore, in grasping the strength improvement effects of clay by organic acid material mixing, it confirmed that organic acid material as soil improving material is effective through unconfined compression strength test and triaxial compression test. Through this test, the definite strength increase is confirmed according to the mixture of the organic acid material and the possibility of soil improvement is also confirmed based on this result. From now on, detailed examination and field test will help closely to definite strength characteristics.

• Journal of the Korean GEO-environmental Society
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• v.9 no.7
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• pp.37-43
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• 2008

The unconfined compressive strength of soil-cement mixed with red mud, an industrial by-product of alumina production, was investigated in the laboratory. The investigation involved laboratory tests under the various conditions such as red mud content, cement content, fly ash content and ratio of soil replacement with sands. The unconfined compressive strength tests were performed at 7, 14 and 21 days after specimen preparation. Results of the study show that the unconfined compressive strength increased as red mud and fly ash content decreased and cement content increased. Increasing the soil replacement ratio with sands had an insignificant effect on compressive strength because the soil had a similar particle size as the replacement sands.

• Tunnel and Underground Space
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• v.10 no.1
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• pp.70-79
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• 2000

We carried out NPT-ensemble (constant-number of particles, pressure, and temperature) Molecular Dynamics (MD) simulations for measuring strength anisotropy under uniaxial compressive stress rotated to the crystallographic axes in $\alpha$-quartz. Uniaxial compressive strengths of a single quartz crystal were measured in directions of the a- and c-axis. Measured uniaxial strength of a single quartz crystal was higher in the direction parallel to the c-axis than that measured in the direction normal to the c-axis. However the reverse was found in calculated uniaxial strengths by MD simulation. The contradictive result of strengths was observed in both cases but was found to be different in origin. Strength anisotropy of defectless $\alpha$-quartz crystal in MD simulation is basically caused by structural difference of quartz. By contrast, anisotropy of measured strength in the uniaxial compression test is related to oriented micro-defects developed during crystal growth.

• Journal of the Korean Geosynthetics Society
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• v.7 no.1
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• pp.13-21
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• 2008

To investigate the engineering properties of basalt in Cheju Island, rock samples of Pyosenri basalt, trachy-basalt and scoria were taken from Seoguipo-Si Seongsan-Eup area. The laboratory tests such as absorption test, specific gravity test, permeability test, Schmidt hammer test, elastic wave test and uniaxial compressive testwere carried out for the collected rock samples. The absorption, the specific gravity, the permeability, the elastic wave velocity and uniaxial compressive strengthwere investigated and analyzed as the results of these tests. As the result of regression analysis for the relationship between the rebound values from Schmidt hammer test and the uniaxial compressive strengths from uniaxial compressive test, especially, estimation equations were proposed using the rebound values from Schmidt hammer test. Therefore, the simple method to estimate the uniaxial compressive strength was provided.