• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.23-34
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• 2013

An organic acid material, which can be manufactured by plants extraction, encourages microbe proliferation over time. Microbial activity, which is affected by organic acid, encourages accelerating consolidation with biochemical penetration; soil particles are compacted by microbes and pore water is dissipated quickly. Additionally, $CaCO_3$ for cementation was made by proliferating microbes. Accordingly, tests were conducted to investigate the unconfined compressive strength and permeability of soil samples aged with and without an organic acid. In the 96 days of aging, the strength was generally 1.5~2.5 times greater than those without an organic acid material and permeability was definitely decreased to 74.2~93.1%. SEM analysis showed the change of pore structure and the change of the total bacteria counts revealed the activity of microbes reflecting the engineering characteristics and this material would be an environment-friendly for soil improvement.

• Journal of Conservation Science
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• v.35 no.2
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• pp.177-186
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• 2019

A Termiticide that is applied to the soil treatment method, one of the methods for preventing termites in Korea's wooden cultural properties, will be subjected to the leaching of the effective ingredient in treated soil by the moisture behavior of rain. As a result, termiticide is deteriorated and needs to be reprocessed, but the standards and evaluation methods are nonexistent in korea. Accordingly, a basic indoor evaluation measure was proposed for the evaluation of the effectiveness of the termiticide chamber and the calculation of the reprocessing period. First, avoidance and contact toxicity were assessed at two concentrations of the same termiticide as a method for assessing termiticide suitability. The evaluation of mortality revealed that the soil termiticide used in this experiment was non-repellent, and that death from contact was confirmed. Afterwards, artificial rainfall and soil penetration tests were conducted to determine efficacy of termiticide in soil and the approximate reprocessing period was calculated by comparing the weather data. Persistence evaluation revealed perforation by termites after continuous water exposure of more than about 160 to 170mm of water injection condition. Based on the results, compared with weather data for the last five years, the termiticide of concentration used in this experiment is expected to remain effective for about one year if treated after September. The purpose of this study was to provide basic data for the establishment of a manual for the selection of termiticide for soil treatment by calculating the efficacy for termite mortality and the duration of the leaching effectiveness by water behavior in soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.3
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• pp.207-215
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• 2023

This study was compared the soil environment and growth and yield of onion (Allium cepa L.) treated with non-mulching (NM) and mulching polyethylene film (PEF) and two biodegradable films (BFI and BFII) commonly used in farmhouses. Visual observation confirmed the degradation of BFI and BFII films after 150 days after tansplanting (DAT). BFII increased light penetration into the films and reduced the weight maintenace after 180 DAT, with a high decompostion at 30 days after soil tilling. Soil moisture contents much fluctuated between -14 kP and - 0 kPa in NM plots, increasing the minimum soil temperature of BFI plots. Mulching treatments decreased soil organic matter contents but did not subtantially increase soil mineral nutrients, soil bulk density, and number of bacteria compared to those of NM plots. Onion root growth was increased by PEF and BFI treatments at an early growth stage, 60 DAT, with the most remarkable stem extension observed for PEF and BFI treatments after 150 DAT. PEF and BFI treatments increased the bulb's diameter, length, weight, and lodging at 180 DAT. BFI treatments exhibited a high portion of the "very large" category producing with 55.3 tons ha^-1 based on the classification into bulb size, followed by PE (49.3 tons), NM (9.4 tons), and BFII treatments (2.7 tons) at 230 DAT.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.16-26
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• 2015

To investigate the applicability of physical prospecting technique in soft ground assessment, the resistivity monitoring data of 6 months are acquired. The Multichannel Analysis Surface Wave (MASW) has been additionally performed to identify the shear wave velocity and strength distribution of soft ground. Moreover, by using the Cone Penetration Test (CPT) and laboratory tests of drilling samples, a relationship with the physical prospect data is checked and the reliability of the physical prospect data is increased. Through these activities, the behavior patterns of soft soil are identified by long term monitoring, and the significant relationship between the shear wave velocity and laboratory tests has been confirmed, both of which can be useful in the surface wave exploration to evaluate the strength of soft ground. Finally, using the geostatistical method, 3-dimensional soil base distribution images are obtained about the combined physical prospecting data with heterogeneous data. Through the studies, the nature of entire area can be determined by long term resistivity monitoring for the soft ground assessment in wider area. It would be more economic and reliable if additional exploring and drilling samples can be analyzed, which can reinforce the assessment.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.21-30
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• 2014

In this study, the applicability of the lightweight dynamic cone penetrometer in the domestic slope site was investigated using the weathered granite soil sampled form the Namwon slope site. And then, the lightweight dynamic cone penetration tests according to the change in the degree of compaction and water content were performed and it was analyzed with the correlations between the degree of compaction, the void ratio, the degree of saturation and the value of cone resistance. From the laboratory test results, the cone penetration resistance was rapidly increased in the dry side of the optimum moisture content, and it was largely decreased in the wet side of the optimum moisture content. Moreover, when the degree of compaction and the degree of saturation are large, the cone resistance is increased linearly. And a high correlativity was shown between water content, void ratio, the degree of saturation and the cone resistance. From these results, it is judged that the lightweight dynamic cone penetrometer can be applied to the investigation on the site slope.

• Journal of the Korean Geotechnical Society
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• v.40 no.5
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• pp.7-20
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• 2024

Ground improvement techniques through soil densification are widely used to enhance the cyclic resistance and seismic performance of liquefiable soils. However, most studies have primarily focused on the increase in soil strength before and after ground improvement, with limited investigation into changes in spatial statistical characteristics. This study aims to identify the changes in soil strength and spatial variability due to ground improvement by analyzing data from 19 cases where ground improvement was conducted using timber piles, aggregate piers, and dynamic compaction, with a cone penetration test (CPT) performed pre- and post-improvement. The changes in cone tip resistance were evaluated by comparing cone tip resistance profiles before and after ground improvement, while changes in spatial variability were assessed by examining variations in three parameters of the random field: mean (or trend function), variance, and scale of fluctuation. The results indicate that cone tip resistance generally increased, while inherent variability tended to decrease. The scale of fluctuation, representing spatial autocorrelation, generally increased following ground improvement, with higher initial fluctuation parameters correlating with a greater rate of increase. Furthermore, the probabilistic analysis of liquefaction-induced settlement revealed that changes in the scale of fluctuation due to ground improvement significantly influenced the variability of settlement, underscoring the importance of considering this factor.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.85-97
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• 1999

For a deltaic clay in the mouth of the Nakdong river, OCR was investigated through methods using the results of field measurement, laboratory and field soil tests. As a result, OCRs were obtained around the range of 0.95 to 1.20 by analysis of field measurements, although they were estimated around the values of 0.4 to 0.7 by the results of conventional consolidation tests for the clay. From the dissipation test it was found out that the excess pore pressures scarcely existed in the clay deposit and then the soil was not in the underconsolidated condition. And the OCRs obtained through methods of Mayne(1991) and Cao et al(1996) using the piezocone test and of Mayne & Kemper(1988) using the cone penetration test were in good agreement with those of field measurement.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.1-11
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• 2000

The use of Compaction Grouting evolved in 1950's to correct structural settlement of buildings. Over the almost 50 years, the technology has been developed and is currently used in wide range of applications. Compaction Grouting, the injection of a very stiff, 'zero-slump' mortar grout under relatively high pressure, displaces and compacts soils. It can effectively repair natural or man-made soil strength deficiencies in variety of soil formations. Major applications of Compaction Grouting include densifying loose soils or fill voids caused by sinkholes, poorly compacted fills, broken utilities, improper dewatering, or soft ground tunneling excavation. Other applications include preventing liquefation, re-leveling settled structures, and using compaction grout bulbs as structural elements of minipiles or underpinning. In this paper, on the basis of the case history constructed in this year, a study has been performed to analyze the basic mechanism of the Compaction Grouting. Also, the effectiveness of the ground improvement and the bearing capacity of the Compaction Pile has been verified by the Cone Penetration Test(CPT) and Load Test. Relatively uniform Compaction grouting column could be maintained by planning the Quality Control in the course of grouting. And, the Quality Control Plan has been conceived using grout pressure, volume of grout and drilling depth.

• Journal of the Korean Geosynthetics Society
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• v.14 no.3
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• pp.21-29
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• 2015

An artificial reef is a human-made underwater structure to improve marine environment and to provide a habitat for fish and other ocean wildlife. An artificial reef is placed on the ocean ground. In soft ground like most of the seabed soil, the ground has been settled due to weight of artificial reef. This study investigated the bearing capacity and settlement reduction effect of geosynthetics which were reinforced on the ground in a large size tank. Penetration tests and large soil tank laboratory tests were performed to investigate settlement reduction effect and bearing capacity on artificial reef with different spreading area of geogrid. Laboratory test results indicate that the spreaded geogrid under artificial reef reduce the settlement of ground and increase bearing capacity of ground.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.405-414
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• 1999

The auger and screw piles have known an important evolution during the last decade. Besides the large success of augercast (CFA) piling systems, new systems have been developed combining, to a variable extent, the classical extraction auger with especially designed displacement tools in order to develop screw piles with partial or total lateral soil displacement. These last developments cover the whole range of lateral soil displacement and are more difficult than ever to compare. The authors present the latest evolutions in auger piling systems and compare them with respect to penetration performances, bearing capacities and amount of spoil generated. A special focus is given to a new efficient system: the OMEGA(H) pile in use in Korea since 1997. The results of the Hongcheon site are presented where this R system was applied for a new investment of the Korean National Housing Corporation (KNHC). This first important experience, with the execution of some 1,500 Omega piles with diameter 410 mm, is presented. The piles were installed through loose silty sands down to very dense sands and layers of gravel. The results of full-scale load tests are analysed and show the conformity with requirements of the clients.