• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1396-1403
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• 2009

The Ministry of Construction and Transportation (MOCT) has been constructing a nationwide soil information DB since 2000, as basic data for the construction of 'underground geographical information,' a project under the 2nd National Geo-spatial Information System (NGIS) master plan. The inputted soil information includes not only underground conditions such as the layer depth, type, color, and groundwater level, but also engineering information that can be applied to construction work design, such as on the standard penetration test and the compression test. It is difficult to use this information in soil analysis and design, however, because only the test results are currently available. A web-based geo-spatial information system was developed in this study to facilitate the effective application of the soil information database (DB). First, the space information, layer information, and engineering test information were loaded from the soil information DB in real time, and the earth volume, bearing capacity, and settlement were calculated to develop a web client that will evaluate the ground softness and liquefaction. It seems that the soil information DB can be actively applied to the planning and design of construction works using this system.

• 한국토양비료학회지
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• 제48권3호
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• pp.194-204
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• 2015

Six study sites in Gumi, Goryeong in Gyeongbuk province and Naju in Jeonnam province were selected to investigate soil properties of poorly drained horizons in paddy soils. The horizons were re-established layers which were parent material layers originated from fluvial deposits. Topsoil layers were differentiated from piled parent materials while soil structure of the topsoil layer was massive with striated microstructure. Compaction at soil re-establishment and a lack of structure and aggregate development in these soils may cause the limitation of vertical water movement and result in poorly drained horizons. Soil samples were taken from paddy fields with top soils of sandy loam, silt loam and silty clay loam and re-established soils of coarse and fine texture. The samples were taken from each horizon for the analyses of soil chemical and mineral properties. Soils with re-established soils of coarse texture had greater amounts of sands from top soil texture distributions, while soils with fine texture had greater amounts of silts. Chemical properties of top soils were analyzed from rice cultivated soils at the time of re-establishments and one year after the re-establishments. The coarse texture of the re-established horizons decreased in EC values from 0.23 to $0.11(dS\;m^{-1})$, available phosphate values from 112 to $54(mg\;kg^{-1})$, and exchangeable Ca values from 6.6 to $4.9(cmol_c\;kg^{-1})$. On the other hand, soils with fine texture showed decrease only in pH and exchangeable Ca values. Especially, organic matter and available phosphate contents showed heterogeneous distributions from each horizon. This result may be caused by mixture of plough layer and subsurface layer during and consolidation. Hydraulic conductivity values were low at the boundaries of top soil and parent material layers except SL/coarse soil. Soil microstructure was massive structure without soil clods or pores and showed striated structure. Therefore, re-established paddy fields with fluvial deposits as parent material layers showed limited vertical movements of soil water because of occurrence of compacted layers and less-development of soil clods and aggregates.

• Earthquakes and Structures
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• 제15권6호
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• pp.655-665
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• 2018

Shield tunnels are widely used throughout the world. However, their seismic performance has not been well studied. This paper focuses on the seismic response of a large scale model tunnel in compacted sand. A 9.3 m long, 3.7 m wide and 2.5 m high rigid box was filled with sand so as to simulate the sandy soil surrounding the tunnel. The setup was excited on a large-scale shake table. The model tunnel used was a 1:8 scaled model with a cross-sectional diameter of 900 mm. The effective shock absorbing layer (SAL) on the seismic response of the model tunnel was also investigated. The thickness of the tunnel lining is 60 mm. The earthquake motion recorded from the Kobe earthquake waves was used. The ground motions were scaled to have the same peak accelerations. A total of three peak accelerations were considered (i.e., 0.1 g, 0.2 g and 0.4 g). During the tests, the strain, acceleration and soil pressure on the surface of the tunnel were measured. In order to investigate the effect of shock absorbing layer on the dynamic response of the sand- tunnel system, two tunnel models were set up, one with and one without the shock absorbing layer of foam board were used. The results shows the longitudinal direction acceleration of the model tunnel with a shock absorbing layer were lower than those of model tunnel without the shock absorbing layer, Which indicates that the shock absorbing layer has a beneficial effect on the acceleration reduction. In addition, the shock absorbing layer has influence on the hoop strain and earth pressure of the model tunnel, this the effect of shock absorbing layer to the model tunnel will be discussed in the paper.

• 지질공학
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• 제31권3호
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• pp.257-267
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• 2021

Constraints on the structure and composition of the active layer are important for understanding permafrost evolution. Soil convection owing to repeated moisture-induced freeze-thaw cycles within the active layer promotes the formation of self-organized patterned ground. Here we present the results of ground penetrating radar (GPR) surveys across a selected sorted circle near King Sejong Station, Antarctica, to better delineate the active layer and its relation to the observed patterned ground structure. We acquire GPR data in both bistatic mode (common mid-points) for precise velocity constraints and monostatic mode (common-offset) for subsurface imaging. Reflections are derived from the active layer-permafrost boundary, organic layer-weathered soil boundary within the active layer, and frozen rock-fracture-filled ice boundary within the permafrost. The base of the imaged sorted circle possesses a convex-down shape in the central silty zone, which is typical for the pattern associated with convection-like soil motion within the active layer. The boundary between the central fine-silty domain and coarse-grained stone border is effectively identified in a radar amplitude contour at the assumed active layer depth, and is further examined in the frequency spectra of the near- and far-offset traces. The far-offset traces and the traces from the lower frequency components dominant on the far-offset traces would be associated with rapid absorption of higher frequency radiowave due to the voids in gravel-rich zone. The presented correlation strategies for analyzing very shallow, thin-layered GPR reflection data can potentially be applied to the various types of patterned ground, particularly for acquiring time-lapse imaging, when electric resistivity tomography is incorporated into the analysis.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.137-144
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• 2005

Seismic responses of a building are affected due to the site soil conditions. In this study, linear time history seismic analysis and nonlinear pushover static seismic analysis were performed to estimate the base shear forces of the 3, 5 and 7-story steel structure buildings considering the rigid and soft soil conditions. According to the study results, the steel structure buildings designed for the gravity loads and wind load showed the elastic responses with the moderate earthquake of 0.11g, and the soft soil layer increased the displacement and the base shear force of a building. Therefore it is more resonable to perform an elastic seismic analysis of a building structure with the moderate earthquakes considering the characteristics of the soft soil layer.

• 산업기술연구
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• 제34권
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• pp.45-52
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• 2014

In this paper the settlement characteristic of shallow foundation on sandy soil overlained by rigid ground was investigated by analyzing results of model tests. For model experiments, model tests were performed with sandy soils sampled from the field, changing the relative density of sandy soil and the ratio of thickness of sandy layer(H) to the width of model strip footing(B). As result of tests, settlement of sandy soils increases as the value of H/B increases, whereas it increases with relative density of soil. Bearing capacity decreases as the thickness of the sand layer relative to the footing width increases. In order to analyze the settlement characteristics of sandy ground, the results of model tests were compared with the predicted values using the empirical formulas proposed by Terzaghi, De Beer and Schmertmann. The method by De Beer was found to be in good agreements with test results.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.316-318
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• 2006

The purpose of this research is to write out vulnerability for western area in Jeju island by using drastic method which is the most frequently utilized among the writing techniques of underground water vulnerability. In case of aquifer, it was divided into two types, gravel layer or not and rated. And soil media was rated two kinds of method. Plan 1 is concerned with only soil class and plan 2 is concerned with soil class and gravels (or rocks), Vadose zone was rated differently according to the ratio of gravel layer. In case of plan 1, the scope of drastic index is from the minimum 77 to the maximum 176, on the other hand, plan 2, the scope of drastic index is from the minimum 79 to the maximum 182. In case of using the water quality data of Nitrate from 1994 to 2004, Pearson correlation coefficient are 0.164(Plan 1) and 0.124(Plan 2) and Spearman correlation coefficient are 0.132(Plan 1) and 0.113.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.423-428
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• 2005

If the load of constructing vehicles during the construction work acts on the road or the ground surface on the soft ground, due to the excess stresses in soils the trafficability of the vehicles influences the constructing efficiency, constructing period and so on. Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research represents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer for its vertical and horizontal stress in (1)homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stress turn out to be different in the value of theoretical and actual measurement after the trial examination of model.

• 한국농림기상학회지
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• 제1권2호
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• pp.110-118
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• 1999

This experiment was conducted to characterize the vertical transport trend of dissolved elements through throughfall, stemflow, effluent from Ao layer, and leachate out of soil profile on Pinus koraiensis stand in Experimental Forest of Kyunghee University, located in Kwangju, Kyunggi province for 12 months from July, 1998 to Jun, 1999. In addition, we investigated the content of dissolved elements and the factors influencing the water chemistry concentrations separately collected from the field. Water movement in the process of throughfall and stemflow from precipitation, and rainfall leached from Ao layer into soil water was governed by concentration of through fall, precipitation, rainfall intensity, seasonal variation, and other factors. Also, smaller changes of pH in soil water than that of dissolved elements in soil water could contribute buffer capacity, as well as balancing the concentration between cations and anions.

• 한국토양비료학회지
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• 제50권6호
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• pp.634-643
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• 2017

No-tillage is an effective practice to save labor input and reduce methane emission from the paddy. Effects of tillage and cultivation methods on carbon accumulation and soil properties were investigated in the treatments of tillage-transplanting (T-T), tillage-wet hill seeding (T-WS), minimum tillage-dry seeding (MT-S) and no-tillage dry seeding (NT-S) of rice. Soil carbon was higher in NT-S and MT-S, compared to T-T and T-WS. In NT-S and MT-S, soil carbon contents were the highest in the top soil (5 cm depth) and decreased with soil depth. In T-T and T-WS, however soil carbon contents showed no significant difference up to soil depth of 15 cm from the top. Carbon content was the highest in the soil particle size under $106{\mu}m$ and decreased as the soil particle size increased. Contents of water-stable aggregates in NT-S and MT-S were higher than those of T-T and T-WS. In NT-S and MT-S, contents of water-stable aggregates were the highest in the top soil and significantly decreased with soil depth while no significant difference up to the soil depth of 15 cm in T-T and T-WS. Available $SiO_2$ contents in the top soil were the highest in NT-S and MT-S while the lowest in T-T and T-WS. It is concluded that minimum or no disturbance of soil in rice cultivation can increase carbon accumulation in the soil, especially in the top layer, and subsequently contribute to the formation of the water-stable soil aggregates.