• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.1
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• pp.123-134
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• 2014

Identification of methods to optimize the growth of a plant community, including the capacity of the soil to further sequester carbon, is important in urban design and planning. In this study, to construct and manage an urban park to mitigate carbon emissions, soil organic carbon of varying biomass, different park construction times, and a range of vegetation types were analyzed by measuring aboveground and belowground carbon in Seoseoul Lake Park and Yangjae Citizen's Forest. The urban parks were constructed during different periods; Seoseoul Lake Park was constructed in 2009, whereas Yangjae Citizen's Forest was constructed in 1986. To identify the differences in soil organic carbon in various plant communities and soil types, above and belowground carbon were measured based on biomass, as well as the physical and chemical features of the soil. Allometric equations were used to measure biomass. Soil total organic carbon (TOC) and chemical properties such as pH, cation exchange capacity (CEC), total nitrogen (TN), and soil microbes were analyzed. The analysis results show that the biomass of the Yangjae Citizen's Forest was higher than that of the Seoseoul Lake Park, indicating that older park has higher biomass. On the other hand, TOC was lower in the Yangjae Citizen's Forest than in the Seoseoul Lake Park; air pollution and acid rain probably changed the acidity of the soil in the Yangjae Citizen's Forest. Furthermore, TOC was higher in mono-layered plantation area compared to that in multi-layered plantation area. Improving the soil texture would, in the long term, result in better vegetation growth. To improve the soil texture of an urban park, park management, including pH control by using lime fertilization, soil compaction control, and leaving litter for soil nutrition is necessary.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.133-140
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• 2002

Phosphogypsum is a by-product from the phosphoric acid process for manufacturing fertilizers. It consists mainly of $(CaSO_4.2H_2O)$ and contains some impurities such as$(P_2O_5)$, 불소$(F_-)$, and organic substances. The annual world production of this material is up to 150 million tons and is up to 1.57 million tons in Korea. Therefore studies describe application of phosphogypsum to daily and middle cover materials in landfill. For this Purpose, experiments were performed to evaluate the engineering properties of the material by sieve analysis, specific gravity, consistency of soil, compaction, CBR, permeability, mi environmental characteristics of leaching test, reactor test. The results of this study are as follows : The mixing and layer conditions of CBR value are 6.2~6.3%, coefficient of permeability is $\alpha$$\times10_{-5}~10_{-6}cm/sec$. And leaching test results are far below than those of regulatory requirement of Waste Management Act, Soil Environment Preservation Act in Korea and RCRA in USA. Therefore phosphogypsum can be used as daily and intermediate cover materials in landfill.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.33-41
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• 2009

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM (controlled low strength materials) accelerated flow ability. CLSM has already been stage of commercial use in the foreign countries led by power company. In this study, we estimated the behavior of flexible pipe with flowable backfill materials and sand to compare on the DB24 load. The results showed that the deformation of flexible pipe is affected by types of backfill materials. CLSM shows better behavior characteristics than compacting sand. But numerical and analytical results that peformed to compare to the field test results showed big gap with the field results.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.45-53
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• 2012

Hollows are easily made and bearing capacity is lowered near underground structures of concrete pavement because of poor compaction and long term settlement of the ground. Distresses occur and lifespan is shortened because of larger stress induced by external loadings expected than that in the design. In this paper, the distresses of the concrete pavement slab over box culverts were investigated at the Korea Expressway Corporation(KEC) test road. The transverse cracking of the slabs over the culverts was compared between up and down lines with different soil cover depth. The box culvert without soil cover and concrete pavement were modeled and analyzed by the finite element method(FEM) to verify the transverse cracking at the test road. Wheel loading was applied after self weight of the pavement and temperature gradient of the concrete slab at Yeojoo, Gyeonggi where the test road is located were considered. Positions of maximum tensile stress and corresponding positions of the wheel loading were found for each loading combination. Joint position minimizing the maximum tensile stress was found and optimal slab length over the culverts with diverse size were suggested.

• Journal of the Korean GEO-environmental Society
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• v.14 no.6
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• pp.31-38
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• 2013

This study carried out fundamental study on the forest road pavement method of cementing the ground using the compaction equipment after laying by mixing with eco-friendly stabilizer, natural soil and water. Target strength of pavement was set to 2.0MPa and the specimen was produced per mixing ratio of cement, kinds of natural soil and curing period to evaluate the durability and unconfined compressive strength. Unconfined compressive strength test was conducted to compare strength by producing the test specimen mixing environment-friendly cement as well as the test specimen mixing cement with the same mixing ratio. To evaluate the durability, surface abrasion test and water flow resistance test were conducted. In addition, SB and GB tests were conducted using iron marble and golf ball to evaluate the walking satisfaction since it can be used by visitors due to the feature of forest road.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.2
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• pp.43-56
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• 1993

The laboratory tests are performed on how the liquefaction potential of the sea dike structures on the saturated sand or silty sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc. It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magnitude of earthquake(max. surface velocity), N-value(relative density), gradation, consistency(plastic limit), classification of soil(G & vs), ground water level, compaction method, volumetric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefaction potential can be done by the one-dimensional analysis using some geotechnical parameters of soil such as Ip, Υt' gradation, N-value, OCR and classification of soils. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is Fs =0.84 when M = 5.23 or amax= 0.12g. With sea dike structures H = 42.5m and 35.5m on the same site Fs= 3.M~2.08 and Fs = 1.74~1.31 are obtained, respectively. local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

• Geomechanics and Engineering
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• v.17 no.1
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• pp.81-95
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• 2019

Due to the importance of soil reinforcement using geotextiles in geotechnical engineering, study and investigation into long-term performance, design life and survivability of geotextiles, especially due to installation damage are necessary and will affect their economy. During installation, spreading and compaction of backfill materials, geotextiles may encounter severe stresses which can be higher than they will experience in-service. This paper aims to investigate the installation damage of geotextiles, in order to obtain a good approach to the estimation of the material's strength reduction factor. A series of full-scale tests were conducted to simulate the installation process. The study includes four deliberately poorly-graded backfill materials, two kinds of subgrades with different CBR values, three nonwoven needle-punched geotextiles of classes 1, 2 and 3 (according to AASHTO M288-08) and two different relative densities for the backfill materials. Also, to determine how well or how poorly the geotextiles tolerated the imposed construction stresses, grab tensile tests and visual inspections were carried out on geotextile specimens (before and after installation). Visual inspections of the geotextiles revealed sedimentation of fine-grained particles in all specimens and local stretching of geotextiles by larger soil particles which exerted some damage. A regression model is proposed to reliably predict the installation damage reduction factor. The results, obtained by grab tensile tests and via the proposed models, indicated that the strength reduction factor due to installation damage was reduced as the median grain size and relative density of the backfill decreases, stress transferred to the geotextiles' level decreases and as the as-received grab tensile strength of geotextile and the subgrades' CBR value increase.

• Journal of the Korean GEO-environmental Society
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• v.23 no.7
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• pp.5-10
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• 2022

The industrial waste is becoming a big problem in the aspect of spatial and environmental in domestic and international. Therefore, the waste reduction and recycling policy has been being implemented as a way to solve this problem. The engineered stone sludge, which is waste, is generated duing the engineered stone production process. since engineered stone sludge is mostly treated by landfill, an increase in the amount of the sludge leads to an increase in landfill sites and treatment costs. therefore, there is a need for a method of resourcization with engineered stone sludge. So, laboratory tests (Plastic and liquid limits, compaction, unconfined compression and permeability test) were conducted to confirm the possibility of using engineered stone sludge mixed with weathered granite soil as a cover material for landfill in this study. The result shows that the mixed soil material with less that 62.5% of engineered stone sludge can be used as a cover material for landfill.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2C
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• pp.119-131
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• 2010

In this study, beneficial use of ocean contaminated sediments were investigated by laboratory and environmental tests, and their prototypes were released. Dredged material from Ulsan port is used for making cement treated samples and lightweight foamed samples, and various engineering tests were performed to identify the compressibility and stress-strain behaviors. Environmental tests were also performed for the beneficial uses. The values of Cu are a little higher than the suggested standard possible for reusing dredged material and equal to the suggested standard alarming for reusing dredged material, which shows environmental harmfulness for the reuse of construction material. In addition, particle size distribution, compaction test, Atterberg limit tests, specific gravity test, and unit weight test were performed to investigate the use of landfill cover materials. The shear strengths of cement treated soils were found to be enough for reclamation works.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.6
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• pp.19-28
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• 2004

Segmental Retaining Wall(SRW) has been variously applying in Civil and Architecture construction. Recently, the application of environmental element in all type's structures came to essential requirement, and the construction cases of retaining wall using reinforced soil and block are more increased than the past. But, this trend more widely was spread environmental element as landscape work for the backside of reinforced retaining wall as well as block itself. New environmental block, Greenstone Block, developed to apply of this tendency. The retaining wall system using Greenstone can be environmental constructing at both block itself and backside of retaining wall. The material tests, the axial compressive strength test of block and bending test of fiber-pipe, exercised to design and construction of vertical SRW, which were satisfied NCMA standard. Through this procedure, Rewall (ver 1.0) was developed, which can be automation design of SRW including internal stability, external stability and local stability. And these can be considered setback of retaining wall, as well the examples of vertical retaining wall using block presented to satisfying the follows; strength of reinforced geotextile, height of retaining wall, surcharge, types of backfill and groundwater level etc. Many problems investigated on after or before of construction were due to local failure, insufficiency of bearing capacity and groundwater level. Especially, the local failure was many occurred to during compaction or after construction, and the cases of SRW construction is similar to the results of model test on vertical SRW.