강우패턴을 고려한 화강풍화토 사면의 침투 및 안정성 분석

이지성,김윤태,Lee. Ji Sung,Kim. Yun Tae 한국방재학회 2013 한국방재학회논문집 Vol.13 No.5

전 세계에서 우기 시 내린 유발강우로 인해 사면파괴가 발생하고, 이러한 사면파괴로 재산 및 인명에 상당한 피해를 주고 있다. 강우로 인한 사면파괴는 불포화 지반에서 모관흡수력의 감소로 인해 얕은 파괴형태로 발생한다. 본 연구에서는 실제 사면파괴 당시의 강우패턴을 산정하여 강우패턴이 화강풍화토 사면의 안정성에 미치는 영향을 분석하고자 하였다. 1999부터 2011년까지 사면파괴가 발생한 화강풍화토 지반을 대상으로 붕괴 유발 강우량을 분석하였다. 취합된 사면붕괴 사례는 총 106개이다. 국내 화강풍화토 사면에서 유발된 사면파괴와 유발강우에 대한 분석을 통해 2개의 사면파괴 유발 강우패턴을 도출하였다: 당일 강우량이 사면파괴에 큰 영향을 미치는 Strong major rainfall(SMR) 패턴과 파괴 하루 전 선행강우가 사면안정성에 영향을 미치는 Strong antecedent rainfall(SAR) 패턴. 또한 비교분석을 위하여 일정강우(Constant rainfall, CR) 패턴을 산정하여 불포화 사면의 침투 및 안정해석을 수행하였다. 해석결과, 사면의 안전율은 강우패턴, 강우강도 및 투수계수에 의존하는 것을 알 수 있다. Many slope disasters occur in many parts of the world during rainy season. Rainfall is one of the significant factors related to the landslides which cause a considerable damage to society. The rainfall-induced landslides in unsaturated slopes generally have shallow failure and are triggered by decrease in matric suction during rainfall. In this paper, effects of rainfall patterns on slope stability of the unsaturated weathered soil were investigated. Landslides inventory consisted of 106 landslides data from 1999 to 2011 was used to induce two rainfall patterns: strong major rainfall(SMR) pattern and strong antecedent rainfall(SAR) pattern. SMR pattern is a rainfall type in which the major rainfall of the landslide event day provides a key role on the landslide occurrence. SAR pattern is that the antecedent rainfall of the 1-antecedent day gives an important role on the landslide occurrence. Constant rainfall pattern was also used for comparison in numerical analysis. Combined seepage and stability analyses were performed to study the stability of slope subjected to various rainfall patterns. The results of numerical analysis indicated that variation of factor of safety of weathered granite slope depended on rainfall pattern, rainfall intensity and soil permeability.

Effect of Rainfall Patterns on the Response of Water Pressure and Slope Stability Within a Small Catchment

Tran The Viet,Giha Lee,Sewook Oh,Minseok Kim 한국지반환경공학회 2016 한국지반환경공학회논문집 Vol.17 No.12

This study aims to assess the influence of rainfall patterns on shallow landslides initiation. Doing so, five typical rainfall patterns with the same cumulative amount and intensity components comprising Advanced (A1 and A2), Centralized (C), and Delayed (D1 and D2) were designed based on a historical rainstorm event in Jinbu. Mt area. Those patterns were incorporated as the hydrological conditions into the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to assess their influences on groundwater pressure and changes in the stability of the slope. The results revealed that not only the cumulative rainfall thresholds necessary to initiate landslides, but also the rate at which the factor of safety decreases and the time required to reach the critical state, are governed by rainfall patterns. The sooner the peak rainfall intensity, the smaller the cumulative rainfall threshold, and the shorter the time until landslide occurrence. Left-skewed patterns were found to have a greater effect on landslide initiation. Specifically, among five rainfalls, pattern (A1) produced the most critical state. The severity of response was followed by patterns A2, C, D1, and D2. Our conclusion is that rainfall patterns have a significant effect on the cumulative rainfall threshold, the build-up of groundwater pressure, and the occurrence of shallow landslides.

Effect of Rainfall Patterns on the Response of Water Pressure and Slope Stability Within a Small Catchment: A Case Study in Jinbu-Myeon, South Korea

Viet, Tran The,Lee, Giha,Oh, Sewook,Kim, Minseok Korean Geo-Environmental Society 2016 한국지반환경공학회논문집 Vol.17 No.12

This study aims to assess the influence of rainfall patterns on shallow landslides initiation. Doing so, five typical rainfall patterns with the same cumulative amount and intensity components comprising Advanced (A1 and A2), Centralized (C), and Delayed (D1 and D2) were designed based on a historical rainstorm event in Jinbu. Mt area. Those patterns were incorporated as the hydrological conditions into the Transient Rainfall Infiltration and Grid-based Regional Slope-stability Model (TRIGRS) to assess their influences on groundwater pressure and changes in the stability of the slope. The results revealed that not only the cumulative rainfall thresholds necessary to initiate landslides, but also the rate at which the factor of safety decreases and the time required to reach the critical state, are governed by rainfall patterns. The sooner the peak rainfall intensity, the smaller the cumulative rainfall threshold, and the shorter the time until landslide occurrence. Left-skewed patterns were found to have a greater effect on landslide initiation. Specifically, among five rainfalls, pattern (A1) produced the most critical state. The severity of response was followed by patterns A2, C, D1, and D2. Our conclusion is that rainfall patterns have a significant effect on the cumulative rainfall threshold, the build-up of groundwater pressure, and the occurrence of shallow landslides.

강우-유출 특성 분석을 위한 자기조직화방법의 적용

김용구(Kim Yong Gu),진영훈(Jin Young Hoon),박성천(Park Sung Chun) 대한토목학회 2006 대한토목학회논문집 B Vol.26 No.1B

강한 비선형성의 경향을 보이고 있는 강우-유출간의 관계를 모형화하기 위한 연구는 다양한 방법론으로 적용되어 활발히 연구되고 있다. 그 중에서 인공신경망을 이용하여 강우-유출간의 관계를 모형화하기 위한 대부분의 연구들은 역전파 학습 알고리즘(back propagation algorithm: BPA), Levenberg Marquardt(LV), radial basis function(RBF)을 이용하였으며, 이들은 강한 비선형성을 나타내는 입ㆍ출력간의 관계를 나타내는데 탁월한 성능을 보이고 있는 것으로 알려져 있고, 자료들의 급격한 변화나 현저한 변화에 대한 뛰어난 적응성을 보여주고 있다. 이러한 인공신경망 이론은 예측뿐만이 아니라 대상자료들의 양상을 분류하여 그 특성을 분석하는 데에도 이용되고 있다. 따라서 본 연구에서는 강우-유출과정의 양상에 따른 분류와 그에 따른 분석을 위해 Kohonen 네트워크 이론에 의한 자기조직화 방법(self-organizing map; SOM)을 적용하였다. 본 연구에서 제시한 방법을 이용한 결과, 강우의 시ㆍ공간적 분포의 불규칙한 변동성을 고려한 강우양상을 분류 할 수 있었으며, 강우-유출간의 특성을 분석한 결과 강한 비선현성을 가지고 있는 강우-유출관계가 SOM에 의해 7개의 패턴으로 구분되었다. Various methods have been applied for the research to model the relationship between rainfall-runoff, which shows a strong nonlinearity. In particular, most researches to model the relationship between rainfall-runoff using artificial neural networks have used back propagation algorithm (BPA), Levenberg Marquardt (LV) and radial basis function (REF). and They have been proved to be superior in representing the relationship between input and output showing strong nonlinearity and to be highly adaptable to rapid or significant changes in data. The theory of artificial neural networks is utilized not only for prediction but also for classifying the patterns of data and analyzing the characteristics of the patterns. Thus, the present study applied self?organizing map (SOM) based on Kohonen's network theory in order to classify the patterns of rainfall-runoff process and analyze the patterns. The results from the method proposed in the present study revealed that the method could classify the patterns of rainfall in consideration of irregular changes of temporal and spatial distribution of rainfall. In addition, according to the results from the analysis the patterns between rainfall-runoff, seven patterns of rainfall-runoff relationship with strong nonlinearity were identified by SOM.

하수관거 통수능 해석을 위한 Huff 모형과 ABM 법의 적용성 분석

현인환,김두일,전승희 대한상하수도학회 2022 상하수도학회지 Vol.36 No.4

The sewer capacity design have been based on the Huff model or the rational equation in South Korea and often failed to determine optimal capacity, resulting in frequent urban flooding or over-sizing. A time distribution of rainfall (i.e., Huff or ABM method) could be used instead of a rainfall hyetograph obtained from statistical analysis of previous rainfalls. In this study, the Huff method and the ABM method, which predict the time distribution of rain intensity, which are widely used to calculate sewage pipe drainage capacity using the SWMM, were compared with the standard rainfall intensity hyetograph of Seoul. If the rainfall duration was 30 minutes to 180 minutes, the rainfall intensity value calculated by the Huff model tended to be less than the rainfall intensity value of the standard rainfall intensity in the initial 5-10 minutes. As a result, more than 10% to 30% of under-design would be made. In addition, the rainfall intensity value calculated by the Huff model from the section excluding the initial 5-10 minutes of rainfall to the rainfall duration was calculated larger than the value using the standard rainfall intensity equation, which would result in an over-design of 10% to 30%. In the case of a relatively long rainfall duration of 360 minutes (6 hours) to 1,440 minutes (24 hours), it showed an lower rainfall intensity of 60 to 90% in the early stages of rainfall, but the problem of under-design had been solved as the rainfall duration time had elapsed. On the other hand, in the alternating block method (ABM) method, it was found that the rainfall intensity at the entire period at each assumed rainfall duration accurately matched the standard rainfall intensity hyetograph of Seoul.

선행강우패턴을 고려한 화강풍화토 비탈면의 안정성 평가

김현기(Hyun Ki Kim),유민택(Min Taek Yoo),배호석(Ho Seok Bae),박승희(Seung Hee Park),고가연(Ga Yeon Ko) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.10

강우경계조건 변화(일정, 증가, 감소, 혼합)와 지표면 침투 수량변화(실효우량 적용)에 따른 비탈면의 안정해석을 수행함에 의하여 강우조건 변화에 따른 화강풍화토 비탈면의 안정성 평가방안을 검토하였다. 해석결과, 강우경계조건에 따라 안전율이 변화하고 있으며, 실효우량을 적용한 선행강우의 영향도 크게 받고 있어, 지역 강우특성을 반영한 강우경계조건 및 실효우량을 적용한 비탈면 안정해석이 요구된다고 판단되었다. Rainfall infiltration is one of the main causes in slope failure. It leads unstable condition of a slope because of increase of soil unit weight, strength reduction, variation of groundwater level etc. Generally the way how to set up a boundary condition of rainfall infiltration is very important to analyze slope stability. In Korea, engineers use IDF curve to set up a boundary condition of rainfall infiltration. It means constant rainfall intensity to be applied in a certain period. But, there is a rare case to consider rainfall patterns and antecedent rainfall. In this study, variations of slope stability under various rainfall patterns and effective rainfall concept are executed by numerical analysis. Factor of safety is affected by boundary conditions of rainfall infiltration and antecedent rainfall by effective rainfall. It is judged that regional rainfall condition and effective rainfall should be considered in slope stability analysis.

감천유역에 대한 강우양상 발생 영향인자의 규명 및 해석

안기홍,조완희,한건연,Ahn,Ki-Hong,Cho,Wan-Hee,Han,Kun-Yeun 한국방재학회 2009 한국방재학회논문집 Vol.9 No.2

우리나라는 기후의 계절적 변화가 뚜렷하며 지역별 시간에 따른 강우발생의 특성이 다양하다. 이러한 계절적, 지역적 강우특성의 반영은 수공구조물의 설계 및 안정성 평가 시 매우 중요하다. 이때 설계 강우량의 선정을 위해 적절한 강우 지속시간, 강우량, 그리고 시간에 따른 강우양상을 결정해야 한다. 일반적으로 수공구조물의 설계 및 신뢰도 평가 시 설계강우에 대한 시간적 강우양상의 결정은 매우 중요하다. 본 연구에서는 강우사상을 분리하여 각 강우사상의 무차원화를 실시하였고 이를 4가지 양상으로 구분하여 감천유역의 시간에 따른 강우발생에 영향을 주는 인자를 규명하고자 하였다. 이 분석은 강우관측소의 지리학적 위치, 강우량, 강우 지속시간, 계절, 태풍 및 장마, 건 우기에 관련된 시간에 따른 강우양상의 발생빈도의 상관관계를 통한 분할표에 의한 군집분석을 통해 실시되었다. 본 연구를 통해 해당 지역에 대한 시간에 따른 강우양상 발생의 영향인자를 파악할 수 있으며 이는 결국 수공구조물의 설계 및 평가뿐 만 아니라 유역의 홍수대책수립 시 매우 중요한 사전자료로 활용될 수 있다. In South Korea, seasonal, local and temporal climatic characteristics are variable in rainfall patterns. To design or assess the reliability of hydrosystem, information about the rainfall event under consideration is important. In this process, the complete description of a design storm involves the specification of rainfall duration, depth, and its temporal pattern. Generally, to use an appropriate temporal pattern for a design storm is of great importance in the design and evaluation of hydrological safety for hydrosystem. For purpose of selecting of factors affecting the occurrence of rainfall patterns, Huff`s dimensionless method was executed and examined by statistical contingency tables analysis through which the inter-dependence of the occurrence frequency of rainfall patterns with respect to geographical location, rainfall duration and depth, and seasonality is investigated. This analysis result can be used to establish flood policies and to design or assess the reliability of hydrosystem.

강우 패턴이 산사태 발생에 미치는 영향: 원주, 춘천을 대상으로

김현욱,김백조 한국자료분석학회 2019 Journal of the Korean Data Analysis Society Vol.21 No.3

Landslide is one of natural disasters that cause land degradation and threaten people's lives and property. In Korea, more than 70% of the land is mountainous, and there is a high risk of landslides due to the residential form close to mountainous areas. Although Wonju-si and Chuncheon-si are urban areas in Gangwon province, except for military areas, they belong to landslide hazard area. In 2011, despite the fact that the total number of severe rain storm and heavy rainfall during summer in Wonju-si was higher than that in Chuncheon-si, more landslide damage occurred in Chuncheon-si. In this study, the correlation between rainfall pattern and landslide occurrence was analyzed using logistic regression analysis for landslide cases of Wonju-si and Chuncheon-si in 2010, 2011 and 2013. As a result, landslides occurred when the severe rain storm was observed continuously for more than 2 hours in both areas. Also, severe rain storm was more sensitive to landslide than 24 hour cumulative rainfall. The possibility of landslide was statistically analyzed to be about 4.64 times when the severe rain storm were continuous and about 1.04 times when the accumulated rainfall of 24 hour increased. Accordingly, it was found that the effects of continuous observation time of severe rain storm and accumulated rainfall of 24 hours on landslide occurrence were important in both areas. 산사태는 국토 황폐화의 원인인 동시에 국민의 재산과 생명을 위협하는 자연재해이다. 우리나라는 국토의 70% 이상이 산지지형이며 산지에 근접한 주거형태로 인해 산사태의 위험성이 높다. 원주시와 춘천시는, 강원도 지역의 도심지임에도 불구하고, 군사지역을 제외하면 산사태 위험지역에 속한다. 2011년의 경우, 원주시가 여름철 총강우량과 집중호우의 발생횟수가 춘천시보다 많았음에도 불구하고 춘천시에 더 많은 산사태 피해가 발생했다. 이 연구에서는 2010년, 2011년, 2013년 원주시와 춘천시의 산사태 사례를 대상으로 강우패턴과 산사태 발생과의 연관성을 로지스틱 회귀분석을 이용해 분석했다. 그 결과, 두 지역 모두 집중호우가 2시간 연속적으로 관측되었을 때 대부분 산사태가 발생했다. 또한 24시간 누적강우량에 비해 집중호우의 발생이 산사태에 더 민감하게 나타났다. 통계적으로 산사태의 발생 가능성은 집중호우가 연속될 경우에 약 4.64배, 24시간 누적강우량이 증가할수록 약 1.04배로 각각 증가하는 것으로 조사되었다. 이에 따라 두 지역의 집중호우의 연속 관측시간과 24시간 누적강우량이 산사태 발생에 미치는 핵심요인임을 알 수 있었다.

WRF 모형의 집중호우사상 시공간적 패턴 재현 능력 평가

이정훈,장수형,김상단 한국방재학회 2015 한국방재학회논문집 Vol.15 No.5

This paper presented a base study for new methodology that uses a physical based regional climate model that can also incorporate the effect of the nonstationarity of atmospheric process. To this end, we examined the capability of the WRF in reproducing the selected historical heavy rainfall events over Korea. WRF used the NCEP FNL reanalysis data, RTG Sea Surface Temperature data and ADP Global Surface Observational Weather data for its initial and boundary conditions. Nine experiments are carried out by changing the physics option (microphysics processes and cumulus parameterization process). Numerical simulation results showed a big variation in rainfall according to initial and boundary condition and cumulus parameterization. In physics option, WRF single-Moment 6-class scheme and New Kain-Fritsch scheme were reasonably reproduced in spatial distribution of rainfall, but the amount was overestimated and dose not reproduce temporal distribution of rainfall. This indicates that a new methodology necessary to WRF for hazard mitigation. 본 연구는 대기 프로세스의 비정상성의 효과를 반영할 수 있는 물리적 기반의 지역 기후 모델을 이용하는 새로운 방법을 제시하기 위한 기반연구이다. 이를 위해 WRF를 이용하여 과거 호우사상을 재현하였고 모의능력을 평가하였다. 모형의 초기조건 및 경계조건을 설정하기 위해서 NCEP의 재분석 자료와 해수면 온도 자료, 지상관측 자료가 사용되었다. 미세물리 과정과 적운 모수화 과정을 변경해가며 총 9개의 수치 실험이 실시되었다. 수치모의 결과는 강수량이 초기조건 및 경계조건과 적운 모수화에 영향을 받는 것으로 나타났다. 물리 옵션 중에서 WRF single-Moment 6-class 방안과 New Kain-Fritsch 방안은 강우의 공간적인 분포는 합리적으로 재현하였지만, 총 발생강수량이 과대 산정되었으며, 시간적인 분포는 재현하지 못했다. 이는 방재분야에 WRF를 적용하기 위해서는 새로운 방법론이 필요하다는 것을 나타낸다.

Estimating Irrigation Requirement for Rice Cropping under Flooding Condition using BUDGET Model

Seo, Mi-jin,Han, Kyung-Hwa,Zhang, Yong-Seon,Jung, Kang-Ho,Cho, Hee-Rae 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.4

This study explored the effect of rainfall pattern and soil characteristics on water management in rice paddy fields, using a soil water balance model, BUDGET. In two sites with different soil textural group, coarse loamy soil (Gangseo series) and fine soil (Hwadong series), respectively, we have monitored daily decrease of water depth, percolation rate, and groundwater table. The observed evapotranspiration (ET) was obtained from differences between water depth decrease and percolation rate. The root mean square difference values between observed and BUDGET-estimated ET ranged between 10% and 20% of the average observed ET. This is comparable to the measurement uncertainty, suggesting that the BUDGET model can provide reliable ET estimation for rice fields. In BUDGET model of this study, irrigation requirement was determined as minimum water need for maintaining water-saturated soil surface, assuming 100 mm of bund height and no lateral loss of water. The model results showed different water balance and irrigation requirement with the different soil profile and indicated that minimum percolation rate by plow pan could determine the irrigation requirement of rice paddy field. For the condition of different rainfall distribution, the results presented different irrigation period and amounts, representing the importance of securing water for irrigation against different rainfall pattern.