• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.253-262
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• 2019

This paper described the evaluation results on unconfined compressive strength characteristics of CLSM with paper sludge ash, in order to develop a CLSM that can prevent sewer pipe damage. The flowability test and the unconfined compressive strength test were performed according to mix design condition of CLSM. The flowability test result showed that the water content, which can satisfy the flowability criteria, was 24% to 32% according to the mix design condition. The results of unconfined compressive strength test showed that the strength incremental ratio was high between 1 and 7 days of curing time, and the strength at this time was more than about 50% of the strength at 28 days of curing time. The strength of CLSM was greatly influenced by fly ash. However, it was analyzed that the mixture of paper sludge ash is required when the reference strength of CLSM is considered. Although the strength of the high cement ratio was higher than that of the low cement, a cement ratio of 5% would be a reasonable mix design condition of CLSM.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.3
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• pp.2003-2012
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• 1970

In order to the influence of grain size distribution on compressive strength and coefficient of permeability, unconfined compression test and permeability test were performed for seventy samples that have various grain-size distributions. Its results are as follows: 1. Maximum unconfined compressive strength appears at the dry side of optimum moisture content. 2. Unconfined compressive strength is proportional to the increase of percent passing of No. 200 sieve. 3. Precent of deformation in failure increases in proportion to the increase of percent passing of No. 200 sieve, and modulus of No. 200 sieve, and modulus of deformation also increases in proportion to percent passing of No. 200 sieve. 4. Unconfined compressive strength increases in proportion to uniformity coefficient, liquid limit and plastic index, but it decreases gradually according to the increase of coefficient of grading and classification area. 5. Maximum dry density decreases according to the increase of void ratio. 6. Coefficient of permeability decreases according to the increase of percent passing of No. 200 sieve, and when percent of No. 200 sieve, and when percent passing of No. 200 enlarged more than 40%, it becomes less than $10^{-6}cm/sec$ which is the limit of coefficient of permeability of core material for earth dam proposed by Lee. 7. Coefficient of permeability increases according to the increase of coefficient of grading, classification area and index of Talbot formula r, but it was rather decrease by the increase of uniformity coefficient. 8. Coefficient of permeability seems to depend on the size and the shape of the flow path which is a series of void to be concerned by the size and the proprton of soil grain, even though void ratios are same.

• Geomechanics and Engineering
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• v.23 no.4
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• pp.339-349
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• 2020

This study investigates the feasibility of using the results of the UPV (ultrasonic pulse velocity) test to assess the UCS (unconfined compressive strength) of unsaturated soil. A series of laboratory tests was conducted on samples of unsaturated lateritic soils of northern Taiwan. Specifically, the unconfined compressive test was combined with the pressure plate test to obtain the unconfined compressive strength and its matric suction (s) of the samples. Soil samples were first compacted at the designated water content and subsequently subjected to the wetting process for saturation and the following drying process to its target suction using the apparatus developed by the authors. The correlations among the UCS, s and UPV were studied. The test results show that both the UCS and UPV significantly increased with the matric suction regardless of the initial compaction condition, but neither the UCS nor UPV obviously varied when the matric suction was less than the air-entry value. In addition, the UCS approximately linearly increased with increasing UPV. According to the investigation of the test results, simplified methods to estimate the UCS using the UPV or matric suction were established. Furthermore, an empirical formula of the matric suction calculated from the UPV was proposed. From the comparison between the predicted values and the test results, the MAPE values of UCS were 4.52-9.98% and were less than 10%, and the MAPE value of matric suction was 17.3% and in the range of 10-20%. Thus, the established formulas have good forecasting accuracy and may be applied to the stability analysis of the unsaturated soil slope. However, further study is warranted for validation.

• Journal of the Korean GEO-environmental Society
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• v.15 no.7
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• pp.31-38
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• 2014

For analysis of mechanics properties of soil cement, unconfined compressive strength has been proposed by existing case studies. In this study, mechanical changes with water content of silt, curing time and cement content were analyzed through unconfined compressive strength test. In addition, the changes for B factor by Abrams were compared with existing case studies after the prediction equations could be proposed about the unconfined compressive strength of admixed cement soil. Especially, the B constant factor was changed with soil characteristics and curing time. For analysis results of appropriateness status and unconfined compressive strength, consideration of variable form was titrated. The prediction equations at low plasticity silt admixed using the uniaxial compressive strength with applying Abrams's equation and considering cement content, curing time is proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.18-25
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• 2020

The unconfined compressive strength of lightweight treated soils strongly depends on mixing ratio. To characterize the relation between various LTS components and the unconfined compressive strength of LTS, extensive studies have been conducted, proposing normalized factor using regression models based on their experimental results. However, these results obtained from laboratory experiments do not expect consistent prediction accuracy due to complicated relation between materials and mix proportions. In this study, deep neural network model(Deep-LTS), which was based on experimental test results performed on various mixing conditions, was applied to predict the unconfined compressive strength. It was found that the unconfined compressive strength LTS at a given mixing ratio could be resonable estimated using proposed Deep-LTS.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.42-49
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• 2008

Recently many countries have become interested in the development of cold or arctic regions. The construction of engineered structures in those regions demands an understanding of the deformation characteristics of frozen soil. However, an understanding of frozen soil behavior poses difficult problems owing to the complex interaction between the soil particles and the ice matrix. In this research, a series of laboratory tests was performed to investigate the variations in the unconfined compression strength and split tensile strength of weathered granite soil and mixed soil (standard sand and kaolinite) in 15 degrees below zero environments. In the frozen soil tests, specimens were prepared with various water and clay contents, and then the interrelationships between four factors (water content, clay content, unconfined compression strength, split tensile strength) were analyzed. The test results were summarized as follows; as the water content was increased, the unconfined compressive and split tensile strengths also increased in frozen soil. However as the clay content was increased, the unconfined compressive and split tensile strengths were lowered. In the case of frozen soil that contained little clay content, the strength decreased rapidly in mixed soil (standard sand and kaolinite) when the frozen specimen was broken. On the other hand, in the cases of mixed soil that contained a high clay content and weathered granite soil, the strength decreased relatively slowly.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.5-11
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• 2021

The compacted bentonite buffer is one of the most important components in an engineered barrier system (EBS) to dispose of high-level radioactive waste (HLW) produced by nuclear power generation. The compacted bentonite buffer has a crucial role in protecting the disposal canister against the external impact and penetration of groundwater, so it has to satisfy the thermal-hydraulic-mechanical requirements. Even though there have been various researches on the investigation of thermal-hydraulic properties, few studies have been conducted to evaluate mechanical properties for the compacted bentonite buffer. For this reason, this paper conducted a series of unconfined compression tests and obtained mechanical properties such as unconfined compressive strength, elastic modulus, and void ratio of Korean compacted bentonite specimens with different water content and dry density values. The unconfined compressive strength and elastic modulus increased, and the Poisson's ratio decreased a little with increasing dry density. It showed that unconfined compressive strength and elastic modulus were proportional to dry density. However, there was not a remarkable correlation between mechanical properties and water content.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.37-44
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• 2006

This paper investigates strength characteristics and stress-strain behaviors of geogrid mixing reinforced lightweight soil. The lightweight soil was reinforced with geogrid in order to increase its compressive strength. Test specimens were fabricated by various mixing conditions including cement content, initial water content, air content and geogrid layer and then unconfined compression tests were carried out. From the experimental results, it was found that unconfined compressive strength as well as stress-strain behavior of lightweight soil was strongly influenced by mixing conditions. The more cement content that is added to the mixture, the greater its unconfined compressive strength. However, the more initial water content or the more air foam content, the less its unconfined compressive strength. It was observed that the compressive strength of reinforced lightweight soil increased reinforcing effect by the geogrid for most cases. Stress-strain relation of geogrid mixing reinforced lightweight soil showed a ductile behavior rather than a brittle behavior. In reinforced lightweight soil, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of geogrid.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.91-100
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• 2008

This study proposes the equations evaluating the shear strength of cemented sand by analytical interpretation based on Mohr-Coulomb failure criteria, and verifies them using the results of triaxial and unconfined compression tests. The internal friction angle of cemented sand is identical to that of uncemented one regardless of the stress level, while the cohesion intercept of cemented sand is constant before the breakage of cementation bonds. Therefore, the shear strength of cemented sand can be represented as a summation of the shear strength of uncemented sand and the unconfined compressive strength of cemented sand. In addition, the cohesion intercept of cemented specimen can be expressed as a function of unconfined compressive strength and friction angle. In the transition zone, assuming a constant shear strength, the equations to evaluate shear strength and cohesion intercept of cemented sand are also represented. It is observed that the predicted values using these solutions agree well with the experimental results. The experimental results also show a linear relationship between the unconfined compressive strength and the breaking point of cementation bonds.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.64-70
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• 2003

For the unconfined vapor cloud explosion(UVCE) accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated by TNT equivalency model with two estimation methods, such as UVCE I model based on a constant release time and UVCEII model based on a real travel time of vapor by dispersion and analyzed with various release conditions. As a simulation result the simple, easy, and correct method of evaluation of consequences of the UVCE accident was proposed by using consequences of UVCE I model and correlation equations for differences of overpressures between UVCE models, so that this evaluation method could be used easily in the small and medium size enterprises without using the dispersion model.