• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.41-49
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• 2014

Intensive rainfall causes frequent slope failures at the shallow depths of slopes. Because soil layers at shallow depths of slopes usually become dense, and its permeability and soil strength vary according to depth, forensic studies and stability analyses of shallow slope failure need to consider the depth-variant soil properties. In this study, the effect of depth-variant soil properties on surface failure of slopes during rain infiltration is investigated using numerical analysis. Three different cases considering depth-variant soil properties were conducted and the results were compared. For the analysis, undisturbed soils at three different depths were sampled at actual slope failure sites and the properties including strength and permeability characteristics at each depth were obtained. Stability analysis and seepage analysis were conducted using actual rainfall records. The comparison of the results shows that analysis could lead to an erroneous conclusion according to the way of considering depth-variant soil properties. The case in which depth-variant soil properties were considered predicted similar failure times and failure shapes with the actual failure. Therefore it is recommended that the depth-variant soil properties should be considered for the analysis of shallow slope failure during rain infiltration.

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.109-114
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• 2013

This paper describes the global stability of the reinforced earth wall, which was collapsed by heavy rainfall. The seepage analysis was conducted to confirm the change effect of groundwater level on slope with reinforced earth wall. The seepage analysis result confirmed that the change of groundwater level is greatly influenced by rainfall. According to the change of groundwater level, the global stability analysis with reinforced earth wall was conducted based on the results of seepage analysis. The safety factor of the slope was 0.476 when the wall is collapsed firstly. The collapse cause analyzed that soil strength was weaken because the ground was saturated by continuous rainfall. Therefore, the global stability, which is considered heavy rainfall, should be conducted at design and construction of reinforced earth wall.

• Journal of the Society of Disaster Information
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• v.14 no.4
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• pp.421-429
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• 2018

Purpose: This study conducted a slope stability study considering changes in the ground water level due to rain phenomena and the duration of rainfall, that is for the purpose of analyzing the stability of the slope surface of the cut section, seepage numerical analysis is performed by height of slope and rainfall accident, and the characteristics of rainfall was applied reasonably in order to determine the slope change during rain by analyzing rainfall and rainfall pattern due to climate change. Results: As a result of numerical analysis of stability for slope composed of the granite weathered soils according to the characteristics of rainfall(Uniform Rainfall, US Army Corps., Huff's method - 1/4, 4/4), Conclusion: The higher the slope, the smaller the safety factor of the slope, the smaller the elevation of the ground water level as the rainwater seepage does not reach the underground water level. In addition, the ground water level was assessed to be rose significantly in condition of case 3 Huff's method - 1/4, rain pattern with the largest initial rainfall duration, and the safety factor was analyzed to be small.

• Journal of the Korean GEO-environmental Society
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• v.20 no.12
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• pp.49-55
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• 2019

Slope failure analysis entails proper understanding of various factors as well as the characteristics of ground conditions, which are difficult to achieve due to technological limits. Despite a number of past studies to clarify possible factors triggering slope failures, the impact of rainfall characteristics and infiltration rate, which are the key to estimation of slope stability in wet condition, on slope failures still remains unclear. This study has estimated permeability against various unit weights of soil based on constant head permeability tests using Jumunjin standard silica sand. One dimensional infiltration tests were conducted to estimate the infiltration capacity and the amount of infiltration taking into account the permeability and rainfall intensity. The applicability of existing empirical equations for the estimation of infiltration to granular soils was verified on the basis of the test results.

• Geotechnical Engineering
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• v.7 no.1
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• pp.53-68
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• 1991

This paper aims at the investigation of various seepage behavior when rainfall infiltarates into unsaturated ground and understanding of the mechanism for slope instability due to rainfall. For this purpose an experimental study is carried out for model slopes using the test equipment which can simulate various rainfall intensity. In addition, a numerical study is performed for the same dimension and boundary condition as the experimental model. From both the experimental test and numerical analysis the progress of wetting front with time, critical amounts of rainfall, and pore-water pressure development with time are know in detail and their effects on slope stability are described.

• 지반과기술
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• v.7 no.3
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• pp.62-64
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• 2010

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.9-18
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• 2011

This paper described that the failure causes of reinforced slope are analyzed based on the effect of geological and rainfall. The analysis result confirmed that the rainfall has effects on the stability of reinforced slope. Therefore, it was applied to the dewatering method using collector well for slope stabilized, and then the analysis of seepage and slope stability were conducted on slope with the applied method. The results of seepage analysis are corresponded with failure cause by rainfall and the results of slope stability, which is applied to dewatering method, are satisfied with safety factor criterion. Therefore, it confirmed that the dewatering method using collector could be possible to apply in field and reasonable method for slope stabilized during heavy rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.257-257
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• 2011

현업에서 사용하는 유출해석 기본이론은 연속방정식과 운동방정식으로서 운동파가정(kinematic wave analogy)을 기반으로 한 집중수문모형(lumped hydrologic model)에 의하여 수행되고 있지만 집중형 모형은 한 매개변수에 여러 가지의 물리적 과정을 개념화하여 담고 있기 때문에 유출과정에 대한 섬세한 모형화의 제약으로 인하여 유역고유의 매개변수값을 찾기가 쉽지 않은 단점을 가지고 있다. 이에 본 연구에서는 물리적 기반의 2차원 분포형 강우-유출모형을 개발하고자 하며 이는 완전분포형 수문동역학적 모형으로 지표흐름과 침투과정, 기저유출과 관련된 과정을 모의한다. 본 모형은 공간적으로 변화하는 침투량과 소규모 및 대규모의 지형학적 특성을 사용하는 St. Venant 방정식을 사용하고 개발될 모형은 모든 스케일에서의 수심과 유량을 계산할 수 있으며 Richard 방정식(또는 선택적으로 Green-Ampt 방정식 채택)을 이용하여 정밀한 침투량 모의가 가능하다. 또한 레이다등의 고해상도 강우관측자료를 지점자료와 합성하여 입력자료로 사용할 수 있도록하고자 하며 강우-유출모형에 다목적댐이나 보등에서의 유량조절효과를 반영하고, 다목적댐군에서의 연계운영모의가 가능케 함으로서 현업의 운영자들이 실무에서 실질적으로 활용할 수 있는 형태의 모형을 개발하고자 한다. 이는 국내에서의 2차원 분포형 강우-유출모형을 자체 개발함으로서 연구역량을 제고하고, 국내 현업기관에서의 분포형 모형기반의 홍수모니터링 및 전망시스템의 확산에 기여할 것으로 예상된다.

• Journal of the Korean GEO-environmental Society
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• v.11 no.4
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• pp.19-24
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• 2010

Generally, slope behavior is analyzed by 2-dimensional creep model. Creep behavior shows the deformation variation as time goes by without stress increment. Convention 2-dimensional creep analysis does not have the term of stress variation, it means creep analysis could not figure out the relationship of shear strength variation according to the stress variation and displacement. The slope weight and shear strength is directly related and interlocked to the safety variation and displacement of slope, therefore, this phenomenon could be treated and analyzed as combining the hysteresis and creep, the iteration of this process will result in the slope safety. Furthermore, the combined analysis will be the slope analysis considering shear stress, displacement and shear strength with time variation. In real case, because the variation of shear stress and strength happen at the same time, they should be changed into safety factor which is function of them. This paper shows the 3-dimensional variation of unit weight of soil with hybrid analysis considering creep and hysteresis on the seepage and drainage of rainfall, futhermore variations of shear stress and strength which make the safety factor change.

• Journal of the Korean Geotechnical Society
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• v.25 no.2
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• pp.55-66
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• 2009

At the mudstone slope located on the roadside of the Seokri area in Donghae-myeon, Pohang, Gyeongsangbuk-do, this study was performed to analyze the effects of rainfall on the stability of slope through seepage analysis according to the precipitation type of the mudstone slope, referring to the actual case of slope failure. For this, precise geological survey, geophysical exploration and drilling survey for the slope where the failure occurred were performed and followed by analysis of detailed soil layer. For the section where failure surface located, the durability reduction of rocks was measured through slaking/swelling tests and the permeability was measured through in-situ permeability tests for each soil layer. In addition, the change of strength parameter and process of instability were analyzed by back analysis, using Talren 97 and Slope/W programs, in the slope. By applying different precipitation conditions to the geographical conditions of the slope that had actual failure records, the slope stability was analyzed by seepage analysis according to duration of rainfall and rise of groundwater level resulting from the flow of rainfall caused by development of geological structures and the slope surface condition.