• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.4 no.1
• /
• pp.16-23
• /
• 2001

This study was conducted to analyse the relation between physical characteristics of soil surface and wild plants occurrence. Lots of natural occurrence on loamy soil and a little of natural occurrence on perlite. Those were used to observe the wild plants occurrence through the duration. Natural occurrence of wild plants were observed on uniform sand, perlite, loamy soil and 2cms loamy soil layer above the perlite. Uniform sand was compared with different height of drain ditch. The results of analysis were as followed. 1. Wild plants germinated on the uniform perlite layer, they did not grow larger. Because water in large pores of perlite surface drained rapidly and evaporated easily, therefore surface remained low moisture contents. 2. A lot of weed grew on 2cms loamy layer on perlite which stratified above the perlite layer. Because perlite had plenty of soil moisture and soil moisture moved easily from perlite to loamy soil layer. 3. Uniform loamy soil had similar occurrence on the uniform perlite. It was nearly same at surface moisture distribution but lower than layered loamy soil on perlite, and the vertical distributions at soil moisture was totally lower than 2cms loamy soil layer on perlite. 4. Wild plants were grew on uniform sand on different height of drain ditch. In this case, much more wild plants were grew on which had more higher drainage ditch. The number of wild plants occurred when it was affected by soil surface moisture, drain ditch and natural occurrence of wild plants. This could be controlled by layered soil at surface moisture. Therefore weed occurrence can control in planting ground, where soil layer would not be disturbed.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.7
• /
• pp.17-28
• /
• 2017

This paper presents the investigation of dynamic behavior of a single pile in dry sand based on 1g shaking table tests. The natural frequency of soil-pile system was measured, and then a range of loading frequency was determined based on the natural frequency. Additionally, the studies were performed by controlling loading accelerations, pile head mass and connectivity conditions between pile and cap. Based on the results obtained, relatively larger pile head displacement and bending moment occur when the loading frequency is larger than the natural frequency of soil-pile system. However, the slope of the p-y curve is smaller in the similar loading frequency. Also, it was found that inertia force like input acceleration and pile head mass, and relation of the natural frequency of soil-pile system and input frequency have a great influence on the slope of dynamic p-y curve, while pile head conditions don't.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.9 no.1
• /
• pp.1-13
• /
• 2006

The recent environmental protection issue has diminished the supply of sand for soft ground improvements so much that the prices of sand have shown a sudden rise. Plastic material is one of substitutes for sand material, but plastic is nonperishable and doubtable if it has potential environmental hormone disrupting substances. Moderate-priced natural fiber drain board made with coconut coir and jute filter are in the spotlight recently as an alternative material for sand and plastic drain board etc. Natural fiber drain has not only competitive price but also a characteristic of assimilation into the soils after finishing of its own function. Discharge capacity of the fiber drain board evaluated by triaxial type discharge capacity test was relatively lower than that of plastic drain board. Nevertheless, settlement and pore pressure dissipation behaviors of the fiber drain board and the plastic drain board which were installed in the clayey soil during the composite discharge capacity test were almost similar. It was also found that biodegradation of the fiber drain board was in progress until 18 month after installation in the clayey soil, but they had still enough engineering properties to use at field.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.773-784
• /
• 2008

Even if the exploitation of copper slag produced during the smelting process of copper as aggregate for construction purpose has been permitted since 2004 in Korea, the lack of sufficient data enabling to evaluate its long-term stability that is its durability has to date impeded its application. This study intends to investigate experimentally the durability characteristics of 18 and 27 MPa-class commercial concretes in which natural sand (fine aggregates) has been partially replaced by copper slag through accelerated and exposure tests so as to provide bases promoting the application of copper slag concrete. The experimental results revealed insignificant difference of the durability characteristics in most of the mix proportions in which 30% of natural sand was replaced by copper slag. In the case where crushed sand was adopted, tests verified similar characteristics for replacement ratio of 50%. Particularly, the results of the exposure test conducted during 8 years demonstrated that equivalent level of durability was secured compared to the case using natural sand. In the case of 18MPa-class lower grade concrete, exposure test verified also that the physical lifetime similar to 50 years could be secured until carbonation reaches cover depth of 20 mm.

• Journal of The Geomorphological Association of Korea
• /
• v.25 no.2
• /
• pp.63-80
• /
• 2018

The purpose of this study was to investigate the physicochemical characteristics and formation age of sand dunes in the Okjukdong and Dajindong, Daecheong Island. As a result, most of the sand deposited in Okjukdong were composed of medium sized sand with moderately well sorted. The $SiO_2$ and $Al_2O_3$ accounted for a very high proportion of these deposits. There were some differences in characteristics between the sands in the dune and beach, whereas similar characteristics were observed among the materials (OJ-B, OJ-C and OJ-D) in the dune. In case of Dajindong, heterogeneous geochemical characteristics were found in the lower point. It was estimated that this was due to the influence of Daejin-dong black beach. Age dating results showed that uncovered dunes in Okjukdong were deposited $0.44{\pm}0.02$ ~ $0.50{\pm}0.02ka$, and sand depositsin Dajindong were formed $0.16{\pm}0.01$ ~ $0.18{\pm}0.01ka$. In both Okjukdong and Dajindong, sand deposits estimated to be formed 70 years ago, therefore it can be estimated that sand movement was active throughout the area from about hundred years ago. In this study area, the growth of sand dunes has been active in recent several decades or hundred years. It seems that there were different regions where deposits predominated over time. The source of dune sand was also different from time to time. Since the windbreak forest was established, the natural growth of sand dunes was limited, and sand nourishment was carried out by period. Therefore, in order to protect and continuously utilize coastalsand dunesin Daecheong Island, it is necessary to prepare conservation plan.

• KIEAE Journal
• /
• v.6 no.2
• /
• pp.51-57
• /
• 2006

With people's awareness of environment-friendly buildings recently increasing, there is a need to develop environment-friendly construction materials to reduce indoorair pollution levels. Thus, efforts to develop loess finishing materials that can replace the finishing materials currently being used (e.g., gypsum boards and chemical products) are underway. An analysis of the characteristics of domestic loess products,however, revealed that the cracks on loess products can be lessened and their strength can be improved by adding chemical ingredients to them. Thus, this research sought to use 100% natural materials and to develop loess finishing materials. In the experiments that were conducted in this study, appropriate mixture ratios of loess and sand/silica sand were found, and cracks and contraction ratio changes in samples were analyzed by differentiating the ratios of natural ingredients, such as lime, fine jute threads, gypsum, and jute cuttings. Loess'particle size distribution was found to have a high correlation with loess decoration, and it was discovered that the mixture of lime and fine chute threads could improve the contraction ratio. Through this study, which made use of natural ingredients, environment-friendly construction materials that can exercise the original function of loess were developed.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.1
• /
• pp.201-207
• /
• 2003

In this paper, the utilization of waste foundry sand produced in the molding process is studied as a backfill material for underground electric utility systems such as concrete box structures and pipe lines for power supply. The physical, chemical and thermal properties for waste foundry sand are investigated far mechanical stability, environmental hazard and power transmission capacity Also its properties are compared with those of the natural river sand. The test results show that waste foundry sand can be utilized for underground concrete box structures as a backfill material; however, it can not be applied to underground pipe lines due to high thermal resistivity or low power transmission capacity.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1407-1414
• /
• 2009

In this study, a Jeju sand, which contains both siliceous and calcareous materials, was sampled from a beach in Jeju Island. It is observed that the Jeju sand has high extreme void ratios due to the angularity of grains and the intra-particle voids of hollow particles. From cone penetration test using calibration chamber system, it is found that the cone tip resistance($q_c$)-relative density(Dr)-vertical effective stress(${\sigma_v}'$) relation of Jeju sand almost matches to that of high compressible quartz sand. However, this correlation overestimates the relative density of a coastal sediments in Jeju Island maybe due to the cementation effect of this area. From analysis of the results of cone penetration and SPS tests at a coastal area in Jeju Island, it seems reasonable to assume that the coast of Jeju Island is a natural cemented sediments.

• Geomechanics and Engineering
• /
• v.1 no.1
• /
• pp.1-15
• /
• 2009

Many aspects of the behavior of sands are affected by the content of non-plastic fine particles and these various aspects should be included in a constitutive model for the soil behavior. The fines content affects maximum and minimum void ratios, compressibility, shear strength, and static liquefaction under undrained conditions. Twenty-eight undrained triaxial compression tests were performed on mixtures of sand and fine particles with fines contents of 0, 10, 20, 30, 50, 75, and 100% to study the effects of fines on void ratio, compressibility, and the occurrence of static liquefaction. The experiments were performed at low consolidation pressures at which liquefaction may occur in near-surface, natural deposits. The presence of fines creates a particle structure in the soil that is highly compressible, enhancing the potential for liquefaction, and the fines also alter the basic stress-strain and volume change behavior, which should be modeled to predict the occurrence of static liquefaction in the field. The void ratio at which liquefaction occurs for each sand/fines mixture was determined, and the variation of compressibility with void ratio was determined for each mixture. This allowed a relation to be determined between fines content, void ratio, compressibility, and the occurrence of static liquefaction. Such relations may vary from sand to sand, but the present results are believed to indicate the trend in such relations.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.5
• /
• pp.195-207
• /
• 2002

The domestic, quantity of copper slag as a by-product at copper smelting process reaches 700,000 tons annually while its application is limited. Therefore, the secure disposal plan of copper slag is urgently required. For this reason, in this study, copper slag was used as a substitute for sand in Sand Compaction Pile that is one of the improvement methods of soft ground because the particle size distribution of copper slag ranges from 0.15mm to 5m(coarse state) and it maintains stable glassy state environmentally. The geotechnical characteristics of copper slag were evaluated through laboratory model tests and the field application of copper slag was compared with generally used sand by pilot tests. From these experimental results, copper slag's material characteristics, bearing capacity, settlement reduction and improvement effects of surrounding ground were found to be superior to generally used sand. The copper slag can be used as a substitute far sand in the Sand Compaction Pile method and as recycling material of industrial by-product with high econonical and environmental value when natural resources are being exhausted.