• Geomechanics and Engineering
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• 제33권2호
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• pp.133-140
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• 2023

Soil erosion can cause scouring and failures of underwater structures, therefore, various soil improvement techniques are used to increase the soil erosion resistance. The microbially induced calcium carbonate precipitation (MICP) method is proposed to increase the erosion resistance, however, there are only limited experimental and numerical studies on the use of MICP treatment for improvement of surface erosion resistance. Therefore, this study investigates the improvement in surface erosion resistance of sands by MICP through laboratory experiments and numerical modeling. The surface erosion behaviors of coarse sands with various calcium carbonate contents were first investigated via the erosion function apparatus (EFA). The test results showed that MICP treatment increased the overall erosion resistance, and the contribution of the precipitated calcium carbonate to the erosion resistance and critical shear stress was quantified in relation to the calcium carbonate contents. Further, these surface erosion processes occurring in the EFA test were simulated through the coupled computational fluid dynamics (CFD) and discrete element method (DEM) with the cohesion bonding model to reflect the mineral precipitation effect. The simulation results were compared with the experimental results, and the developed CFD-DEM model with the cohesion bonding model well predicted the critical shear stress of MICP-treated sand. This work demonstrates that the MICP treatment is effective in improving soil erosion resistance, and the coupled CFD-DEM with a bonding model is a useful and promising tool to analyze the soil erosion behavior for MICP-treated sand at a particle scale.

• 한국해안·해양공학회논문집
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• 제29권5호
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• pp.269-277
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• 2017

최근, 해변모래의 침식을 방지하기 위해 잠제를 설치하고 있다. 잠제설치는 모래 침식의 손실을 최소화하기 위해 만들어졌다. 이런 이유로, 잠제를 무분별하게 전국적으로 계획하여 건설하고 있다. 그러나 해안선 유지를 위해 설치된 잠제는 상당히 문제가 있는 방법이다. 고가의 건설비, 해양공간이용, 해수수질, 해안선 변화 등의 단점도 있다. 특히, 해양 레저를 즐기는 이용자들은 해상공간이 단절되기 때문에 이를 좋아하지 않는다. 광안리와 같은 해수욕장은 인위적으로 양빈모래를 공급하여 해수욕장을 유지하는 곳이다. 연성공법이란 양빈모래의 유실방지를 위해 수중에 잠재를 대신하여 유동성 재질로 폭 넓은 연성구조물을 설치하는 공법을 말한다. 본 연구는 해변 침식을 완화할 수 있는 연성공법의 일환으로 cell group을 설치하였다. 즉, 양빈모래의 유실을 막기 위해 잠제 대신에 cell group을 사용하여 사빈침식의 정도를 완화 할 수 있는 공법을 적용한 것이다. 2차원 고정상 실험에서 cell group의 설치로 인한 파고감소효과 및 저반사율을 제시하였고, 이동상 수리모형실험에서, cell group 설치로 인한 양빈모래의 포착률과 양빈 모래의 침식방지율을 제안하였다. 따라서 수리모형실험의 결과에 의하면 침식해안의 사빈에 cell group을 설치하면 파고감소효과, 저반사율과, 양빈사의 침식방지율, 양빈사의 높은 포착률에 의해 양빈사의 유출이 방지되어 안정된 해안을 유지할 수 있었다.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1175-1184
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• 2000

Effects of porous wind fences on the wind erosion of particles from a triangular sand pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Flow visualization was carried out to investigate the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the particle size, fence porosity $\varepsilon$ and the height of sand pile. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity $\varepsilon$=30% was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles. With increasing the sand particle diamter, the threshold velocity was also increased. When the height of sand pile is lower than the fence height, threshold velocity is enhanced.

• 한국해양공학회지
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• 제1권1호
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• pp.84-93
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• 1987

A beach nourishment method can be used as one of the beach erosion protection methods which may keep coastal environments whithout constructing coastal structures on the HAE UN DAE beach. The beach nourishmens is affected by a natural condition and artificial condition;a natural condition includes conditions of bottom slope, diameter of bottom materials and waves, and artificial conditions include deposit position, method, diameter and quantity of the nourishing sand. It has accomplished to obtain the deposit position and the best diameter of the nourishing sand from a two-dimensional hydraulic model test, which simulates the erosional HAE UN DAE beach. In this study, the protection of the beach erosion can be maximized when the nourishing sand of 3.3mm in diameter, which is about 5.5.times of the bottom materials in diameter, is deposited layerly in front of the breaker zone which has a water depth of 4.6m.

• 한국환경복원기술학회지
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• 제20권6호
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• pp.35-50
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• 2017

This study is to see the recovery effect of the Deltacon method by investigating the amount of sand deposition, the topographical cross section and the vegetation structure; and to derive the effective recovery method of coastal erosion area. The target areas of this study include Jinri coastal dune, Bajireum coastal dune and Seopori coastal dune in Deokjeok-do Island, Ongjin-gun, Incheon. In order to assess the current status of the coastal erosion area recovery, the soil profile structure map was prepared on the site and then the amount of sand deposition within 1m was calculated indoors. The vegetation recovery status of the costal erosion area was assessed via the analyses of the topographical profile structure and the plant community structure, and we aim to derive the effective recovery plan of the Deltacon method with the results. With the Deltacon method, structures with ductile material, special non-woven fabric bags filled with soil and vegetation can be performed therefore the structuralstability and prevention of sand erosion can be achieved. The amounts of sand deposition of Bajireum coastal dune, Seopori costal dune and Jinri costal dune were calculated $0.98{\sim}2.54m^3$, $1.02{\sim}2.96m^3$, and $0.27{\sim}0.75m^3$, respectively, and it is considered that the costal erosion recovery is actively performed for Bajireum costal dune and Seopori costal dune. The analysis results of vegetation structures by topography show that the installation of the send collecting net in steep areas has been highly effective and the Deltacon-constructed target areas have been restored to vegetation and the costal dune, which is similar to the natural dune. The investigation of the plant community structure in Deokjeok-do Island costal dune, Incheon displayed similar research results of the existing costal dune flora and confirmed the emergence of Lathyrus japonicus, Carex kobomugi, Elymus mollis, Vitex rotundifolia, and Calystegia soldanella and others. In order to carry out further effective recovery with the Deltacon method, improvements to rootage of herbaceous vegetation are needed in areas without foredune herbaceous vegetation, and continuos maintenance & management monitoring of connected windbreak forest to costal dunes are also necessary.

• Geomechanics and Engineering
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• 제25권1호
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• pp.49-58
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• 2021

The resistance of soil to the tractive force of flowing water is one of the essential parameters for the stability of the soil when directly exposed to the movement of water such as in rivers and ocean beds. Biopolymers, which are new to sustainable geotechnical engineering practices, are known to enhance the mechanical properties of soil. This study addresses the surface erosion resistance of river-sand treated with several biopolymers that originated from micro-organisms, plants, and dairy products. We used a state-of-the-art erosion function apparatus with P-wave reflection monitoring. Experimental results have shown that biopolymers significantly improve the erosion resistance of soil surfaces. Specifically, the critical shear stress (i.e., the minimum shear stress needed to detach individual soil grains) of biopolymer-treated soils increased by 2 to 500 times. The erodibility coefficient (i.e., the rate of increase in erodibility as the shear stress increases) decreased following biopolymer treatment from 1 × 10-2 to 1 × 10-6 times compared to that of untreated river-sands. The scour prediction calculated using the SRICOS-EFA program has shown that a height of 14 m of an untreated surface is eroded during the ten years flow of the Nakdong River, while biopolymer treatment reduced this height to less than 2.5 m. The result of this study has demonstrated the possibility of cross-linked biopolymers for river-bed stabilization agents.

• 아시안잔디학회지
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• 제8권3호
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• pp.149-165
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• 1994

This report was investigated on the soil and mineral nutrient erosions in comparison among the vegetation floors of M isranthus sisensis, Arternisia stelleriana, Rhododendron mucronula turn, Zoysia ja-ponira and Pinus deusitlora communities and the naked soil on Mt. Keum-hak in Cheolwon-Koon, The erosion of clay, silt, fine sand and coarse sand of the surface soils under the Z. japonira grass-land was far less then those of M. sinensis, A. stelleriana, R. murronulatum and P. densiflora com-munities and the naked soil, The loss of mineral nutrients due to the soil erosion was the lowest level in the Z. japonira grassland and the highest level in the P. densiflora forest and the naked soil, respectively.

• 한국지리정보학회지
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• 제9권3호
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• pp.82-92
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• 2006

국내 해빈지대는 인위적 개발과 기상학적 현상, 특히 태풍의 영향으로 다량의 모래가 유실되고 있어, 장기적 측면에서 침식이 지속적으로 발생하는 해빈지대의 모니터링이 요구되며, 해빈침식 방지를 위한 종합대책 수립 및 시행 작업이 필요하다. 그러나 현재까지 정확한 측량이 이루어지지 않은 채, 모래 유실에 관한 문제 제기나 일시적 대책 마련에 급급하고 있다. 그러므로 본 연구에서는 해운대 사빈지역을 대상으로, GPS 기법을 이용하여 해안지대의 정확한 공간자료 구축 방법을 제시하고, GIS 기법을 활용하여 태풍 Nabi로 인한 사빈지형 변화를 정량 정성적으로 탐지하고 분석하였다. 연구결과, 태풍 후, 사빈 평균고도는 1.95 m, 총면적은 53,441 $m^2$, 총체적은 104,639 $m^3$로, 호안벽의 영향으로 사빈고도는 0.06m 가량 증가하였으나, 강풍과 북북동의 정온입사파 영향으로 해빈면적은 3,096 $m^2$, 체적은 2,320 $m^3$ 가량 침식하였다. GPS GIS 기법을 통합하여 해안지대의 정확한 공간 DB를 구축하고 해안지형 변화를 정량 정성적으로 분석한다면, 국내 해안침식에 대한 체계적이고 효과적인 대책을 고안할 수 있을 것으로 사료된다.

• 한국환경복원기술학회지
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• 제17권6호
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• pp.1-15
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• 2014

A dredging on erosion control dam has been enforced without evaluation the factors that affect the dredging. In addition, there is the negative effect much more than positive effect by dredging on erosion control dam. Therefore, this study was carried out to develop evaluation indicators and to suggest fieldbook in order to determine whether sand deposits at erosion control dam should be dredged up or not. The most important six evaluation indicators that can decide to dredge up at erosion control dam were obtained from three round delphi technique and were selected in the following order: the current sand deposit ratio(0.339), existence of cultivated land and house downstream(0.276), the slope of streambed(0.162), the amount of movable soil and gravel(0.118), the history of any disasters(0.063), the basin area(0.043). The weighted score for each evaluation indicator were acquired from AHP analysis with respect to the degree of importance and then the modified weighted score for actual measurements were classified as three categories: large(2.53), medium(1.60) and small(1.01). Based on delphi technique, erosion control dam dredging evaluation fieldbook introduced the four evaluation indicators out of the total six evaluation indicators and two low effected evaluation indicators were excluded. This results showed that the values for reliability analysis and consistency ratio were acceptable.

• 한국토양비료학회지
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• 제14권3호
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• pp.104-109
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• 1981

자연강우하(自然降雨下)에서 modified Ellison Cup에 의(依)해 Splash Erosion 양(量)을 각(各) 토성별(土性別) 작촌체계별(作付休系別)로 측정(測定)하였으며 Splash Erosion 양(量)과 강우인자(降雨因子)(R), 토양인자(土壤因子)(K), 작물인자(作物因子)(C)와 비교검토(比較檢討)한 결과(結果) 1. 콩-보리 재배시간중(裁培時間中) Splash Erosion 양(量)은 토성(土性)이 미세(微細)할수록 적었으며 식양토(埴壤土) 7.0ton, 양토(壤土) 9.7ton, 사양토(砂壤土) 9.0ton, 양질사토(壤質砂土) 12.6 ton/10a/년(年)이었다. 2. Splash Erosion 양(量)은 강우인자(降雨困子)(R치(値))와는 정(正)의 상관(相觀), 토양인자(土壤因子)(K치(値))와는 부(負)의 상관(相觀)이 있었다. 3. 작물인자(作物因子)에서 피복도(被覆度)가 50% 이내(以內)에서는 Splash Erosion과 강우인자(降雨因子) 사이에 상관(相觀)을 보였으나 피복도(被覆度)가 증가(增加)할수록 감소(減少)하고 90% 이상(以上)에서는 상관(相觀)이 없었다. 연간(年間) Splash Erosion 양(量)은 10~15ton/10a/년(年) 범위(範圍)이었다. 4. Splash Erosion에 의(依)하여 이동(移動)된 토양(土壤)의 입도(粒度) 분포(分布)는 원토양(原土壤)과 비슷하였으나 세사(細砂) ($250{\sim}100{\mu}$)가 가장 많이 비산(飛散)되었다.