• Geomechanics and Engineering
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• v.24 no.2
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• pp.129-141
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• 2021

The vacuum preloading method has been used in many countries for soil improvement and land reclamation. However, the treatment time is long and the improvement effect is poor for the straight-line vacuum preloading method. To alleviate such problems, a novel combined air booster and straight-line vacuum preloading method for shallow ground treatment is proposed in this study. Two types of traditional vacuum preloading and combined air booster and straight-line vacuum preloading tests were conducted and monitored in the field. In both tests, the depth of prefabricated vertical drains (PVDs) is 4.5m, the distance between PVDs is 0.8m, and the vacuum preloading time is 60 days. The prominent difference between the two methods is when the preloading time is 45 days, the injection pressure of 250 kPa is adopted for combined air booster and straight-line vacuum preloading test to inject air into the ground. Based on the monitoring data, this paper systematically studied the mechanical parameters, hydraulic conductivity, pore water pressure, settlement and subsoil bearing capacity, as determined by the vane shear strength, to demonstrate that the air-pressurizing system can improve the consolidation. The consolidation time decreased by 15 days, the pore water pressure decreased to 60.49%, and the settlement and vane shear strengths increased by 45.31% and 6.29%, respectively, at the surface. These results demonstrate the validity of the combined air booster and straight-line vacuum preloading method. Compared with the traditional vacuum preloading, the combined air booster and straight-line vacuum preloading method has better reinforcement effect. In addition, an estimation method for evaluating the average degree of consolidation and an empirical formula for evaluating the subsoil bearing capacity are proposed to assist in engineering decision making.

• Journal of The Geomorphological Association of Korea
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• v.24 no.1
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• pp.105-116
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• 2017

This article is written in the viewpoint of landscape ecological geography. The coast of South Chung-chong Province will make new characters of region in the development strategies program. This study is to describe geomorphological landscapes of South Chung-chong Province relating with it's environment based on the coast. Although landforms constitute prominent landscape features as tidal flats and rock cliff do, it is nonetheless the features such as beaches, sanddunes, and coastal plains that have various ramifications for human communities. Tidal flats, beaches and coastal sanddunes are special in that their formation is attributable to the combined action of tidal flows, waves and winds. To some extent, the erosion of sand has been a global phenomenon. Human impact are involved. The influence of globalization and expansion of liberal trade appears in regions variously. Individual regions need to secure its competitiveness in the world market. Regions are not value-neutral abstract conception, but must be informal commercialized characters of region. The coast of South Chung-chong Province has experienced rapid and dramatic changes. In industrial times, the middle of west coast Korea turned into a major reclamation at larger scale. Reclaimed land was based on location of industry and mechanized agriculture. The west coast highway and bridges between island and land contributed to the development of west coast transportation. As information society matured, trend and value are changing. Environment and ecology emphasize and rediscover the value of tidal flats and sanddunes. The west coast region now receives attention as eco-tour and sustainable course.

• Geomechanics and Engineering
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• v.34 no.4
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• pp.397-408
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• 2023

Pipe pile walls are commonly used as retaining structures for excavation projects, particularly in densely populated coastal cities such as Hong Kong. Pipe pile walls are preferred in reclaimed land due to their cost-effectiveness and convenience for installation. However, the pre-bored piling techniques used to install pipe piles can cause significant ground disturbance, posing risks to nearby sensitive structures. This study reports a well-documented case history in a reclamation site, and it was found that pipe piling could induce ground settlement of up to 100 mm. Statutory design submissions in Hong Kong typically specify a ground settlement alarm level of 10 mm, which is significantly lower than the actual settlement observed in this study. In addition, lateral soil movement of approximately 70 mm was detected in the marine deposit. The lateral soil displacement in the marine deposit was found to be up to 3.4 and 3.1 times that of sand fill and CDG, respectively, mainly due to the relatively low stiffness of the marine deposit. Based on the monitoring data and site-investigation data, a 3D numerical analysis was established to back-analyze soil movements due to the installation of the pipe pile wall. The comparison between measured and computed results indicates that the equivalent ground loss ratio is 20%, 40%, and 20% for the fill, marine deposit and CDG, respectively. The maximum ground settlement increases with an increase in the ground loss ratio of the marine deposit, whereas the associated influence radius remains stationary at 1.2 times the pipe pile wall depth (H). The maximum ground settlement increases rapidly when the thickness of marine deposit is less than 0.32H, particularly for the ground loss ratio of larger than 40%. This study provides new insights into the pipe piling construction in reclamation sites.

• Journal of Environmental Impact Assessment
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• v.12 no.4
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• pp.291-302
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• 2003

This paper examined the impacts of the regional developments and dwellers behavior on the Seacoast. Seacoast features a variety of landforms which are created by the action of waves and tidal flows. The coastal landforms are found mainly in the interface between land and sea. Although erosional landforms constitute prominent landscape features as sea stack, sea arch, and rock cliff do, it is nonetheless the depositional features such as beaches, tidal flats, offshore bars, deltas, sanddunes, and coastal plains that have various ramifications for human communities. Among these, beaches and coastal sanddunes are special in that their formation is attributable to the combined action of waves, tidal flows, and winds. The main line of discussion in this dissertation is concerned with the transformation of group of beaches sanddunes along the coastline of Chungcheong-Namdo Province. To some extent, the erosion of coastal dunes has been a global phenomenon. The degradation process occurs most actively when the spring tides attack beaches, berms, and foredunes. Also involved in the transformation of coastal dunes are factors of human agency. The extent, speed, and pattern of their morphological changes are a function of land-use pattern. The reclamation of swale and the exploitation of sands as construction material and silica sand, for example, ruin the feature of coastal dunes.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.15-23
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• 2007

This paper presents a shoreline change analysis on a reclaimed land, using a pair of aerial photographs taken before and after the reclamation. Shorelines that are defined by a tide datum, i.e. Approximately Highest High Water Level, were mapped by both analytical and digital photogrammetric methods. The past shorelines were overlapped with digital cadastral map from which areas of retracted and protruded lands were computed. Magnitude of shoreline changes was estimated by calculating areas between the past and present shorelines. Comparisons in terms of areas showed a fairly good agreement between the two methods. However, particularly in the estuary of complex morphology, shoreline mapping by digital photogrammetric method requires images to be scanned at a resolution higher than 1200 dpi.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.4
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• pp.86-94
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• 1993

In this study, a tentative decision-making matrix for village planning in reclaimed land was proposed. The evaluating conditions in the matrix are reclaimed farming acreage and distance. And the indexes for evaluation works are farming acreage required for increasing present farm size to target size in the base of, allowable commuting distance for farming from and effective controlling distance of each village. The village planning strategies are considered into four categories ; upkeep of present village scale, transfer of its superfluous farming acreage to a neighbouring village, enlargement of present village scale and new village construction in reclaimed land. As a case study, the proposed decision-making matrix was applied to 69 villages, which are contiguous to the potential farming area from reclamation works of Yongsan River Basin Comprehensive Development Project Phase Ill and so considered in this study as future farming villages there. From the application results, the following tactics for village planning may be proposed ; principally, upkeep or enlargement of present village scale, but, in an exceptional few cases of standard farming size being 3~5ha, new village construction of normal or satellite scale.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.540-545
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• 2005

Large scale projects of sea-land reclamation have been practiced mainly to enlarge farmland in Korea. Most projects produced estuarine reservoir with dike construction, which might result in water quality problems due to block of natural flowing of stream water to the sea. Applicability of a widely accepted watershed-based water quality assessment tool (BASINS) and its associated watershed model was evaluated on the Hwaong watershed in Korea. BASINS was found to be a convenient and powerful tool for assessment of watershed characteristics, and provided various tools to delineate the watershed into land segments and river reaches, reclassify land use, and parameterize for HSPF simulation. WASP5 is a general purpose modeling system for assessing the fate and transport of conventional and toxic pollutants in surface water bodies. This study involved selection and linkage of available models to be used as a tool in evaluating the effects of BMPs for control on reservoir water quality. Overall,.Linkage of BASINS/HSPF and WASP5 was applicable and found to be a powerful tool in pollutant loading estimation from the watershed and reservoir, and its use is recommended.

• Journal of Korean Society of Rural Planning
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• v.10 no.4 s.25
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• pp.45-54
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• 2004

In this study, the actual states and cases utilizing lake dykes were investigated focusing on large-scale reclamation project in domestic and instances in advanced foreign countries. The attitudes investigation concerning lake dykes utilization was performed to residents in-and-around Saemangeum. According to the research result, in domestic the utilization of lake dyke have not attracted attention because maximizing land use, which was the primary purpose of reclamation project at the early stage, has been emphasized so far. The advanced foreign countries, however, not only make use of farmland, but also develop activities employing lake dykes. According to the result of an analysis for local residents' attitudes, they want to be used Saemangeum lake dykes as a multifunctionality facilities performing a role of environment friendly equipment as well as a breakwater. They also require further investigation and to be introduced new system far utilizing as a multifunctionality facilities. Recently, green tourism is getting attention more and more owing to laying stress on balanced development of country and improvement on life quality of rural residents and launching five days in duty. It is believed that on this favorable trend lake dykes an be employed as a primary tourism resource if its utilization is developed actively.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.185-192
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• 2000

Recently, the hydraulic fill method is commonly used in many reclamation projects due to lack of fill materials. The method of hydraulic fill in reclamation is executed by transporting the mixture of water-soil particles into a reclaimed land through dredging pipes, then the dredged soil particles settle down in the water or flow over an out flow weir with the water. In the present study, practice each three method in order to suggest method of determining the loss rate of the dredged fills. The first sieve and hydrometer analysis were performed with the soil samples obtained before and after dredging and then apply theory of particle breakage, the second compare with the volume of dredged soil between at the dredging area and the target pond and the last compare with weight of dredged soil between before and after dredging at the dredging area and in the target pond for estimating the amount of soil particles residual at the reclaimed area and the loss of soil particles passed through the weir. In addition to compare with the loss ratio between as using Marsal's modified theory of particle breakage and measured weight and volume in the field.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.491-498
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• 2004

In recent years, as an effort to grasp the leading position in the field of maritime trading, new ports and container terminals arc now under construction. Old ports are extended. At the beginning, stones were thrown down to form stone embankments, that is stone-dams, in the outer and inner boundaries of the planned reclamation-land. S.C.P(Sand Compaction Pile) works are often needed to improve the stability of stone-dams, where marine sediments arc relatively thick. Here, interests are centered on the shape of stone body. In this, drilling work won't provide a sufficient resolution. In addition, the result corresponds to only one borehole point information. Thus, the aim of this paper is to introduce an affordable technology, that is, a combined geophysical method(seismic tomography + Televiewer) enables to get the whole information about stone-dam section. The measuring and evaluating procedure is described in detail with an emphasis on dealing with the use of seismic detonator, proper borehole deployment and integrated data analysis. Examples of field experiments at Busan new port are illustrated, which will prove the benefit of combined geophysical method.