• Title/Summary/Keyword: Surface slope failure

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Analysis of Slope Stability in Slopes of Failed and not Excavated (붕괴된 사면과 굴착되지 않은 사면의 안정성 검토)

  • 유병옥;김경석;이용희
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.06a
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    • pp.129-144
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    • 2003
  • Generally, investigation methods of cut slope are conducted only geological surface survey to gain engineering geological data of cut slopes. These methods have many problems such as limitations of investigation for a special area. So geophysical investigations such as geotomography, seismic and electrical resistivity methods have been used to search for failure surface in potential failure slopes or failed slopes. But investigation method using the borehole camera is recently a used method and it is thought that this method is more reliable method than other investigation methods because of being able to see by the eyes. Therefore, this paper was conducted investigations of borings and BIPS(Borehole Image Processing System) to search for potential sliding surfaces and was applied to obtain information of discontinuity on failed and potential failure slope in highway. As the results of BIPS, we could decide potential sliding surface in the slope, conducted to check slope stability and decided slope stability measures.

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Experimental Study on the Slope Failure of Embankment (성토사면의 붕괴에 관한 실험적 연구)

  • 강우묵;이달원;지인택;조재홍
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.35 no.3
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    • pp.47-62
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    • 1993
  • The laboratorv model test was carried out to investigate the behavior of pore water pressure, the critical amount of rainfall for slope failure, the pattern of failure, and the variation of seepage line at the slope with the uniform material of embankment by changing the slope angles and rainfall intensities. The results were was summarised as follows : 1.At the beginning stage of rainfall, the negative pore pressure appeared at the surface of slope and the positive pore pressure at the deep parts. But, the negative one turned into the positive one as the rainfall continued and this rapidly increased about 50 to 100 minutes before the slope failure. 2.The heavier the rainfall intensity, the shorter the time, and the milder the slope, the longer the time took to reach the failure of slope. 3.As the angle of the slope became milder, the critical amount of rainfall for slope failure became greater. 4.Maximum pore water pressure was 10 to 40g/cm$^2$ at the toe of slope and 50 to 90g/cm$^2$at the deep parts. 5.In the respect of the pattern of slope failure, surface failure of slope occurred locally at the toe of slope at the A-soil and failure of slope by surface flow occurred gradually at the top part of slope at the B-soil. 6.As the rainfall continued and the saturation zone in the embankment was formed, the seepage line went rapidly up and also the time to reach the total collapse of slope took longer at the B-soil. 7.As the position of the seepage line went up and the strength parameter accordingly down, the safety factor was 2.108 at the A-soil and 2.150 at the B-soil when the slope occured toe failure. Minimum safety factor was rapidly down to 0.831 at the A-soil and to 0.936 at the B-soil when the slope collapsed totally at the top part of slope.

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Static and quasi-static slope stability analyses using the limit equilibrium method for mountainous area

  • Hosung Shin
    • Geomechanics and Engineering
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    • v.34 no.2
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    • pp.187-195
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    • 2023
  • Intensive rainfall during the summer season in Korea has triggered numerous devastating landslides outside of downtown in mountainous areas. The 2D slope stability analysis that is generally used for cut slopes and embankments is inadequate to model slope failure in mountainous areas. This paper presents a new 3D slope stability formulation using the global sliding vector in the limit equilibrium method, and it uses an ellipsoidal slip surface for static and quasi-static analyses. The slip surface's flexibility of the ellipsoid shape gives a lower FS than the spherical failure shape in the Fellenius, Bishop, and Janbu's simplified methods. The increasing sub-columns of each column tend to increase the FS and converge to a steady value. The symmetrical geometric conditions of the convex turning corners do not indicate symmetrical failure of the surface in 3D analysis. Pseudo-static analysis shows that the horizontal seismic force decreases the FS and increases the mass volume at the critical failure state. The stability index takes the FS and corresponding sliding mass into consideration to assess the potential risk of slope failure in complex mountainous terrain. It is a valuable parameter for selecting a vulnerable area and evaluating the overall risk of slope failure.

A new analytical model to determine dynamic displacement of foundations adjacent to slope

  • Varzaghani, Mehdi Imani;Ghanbari, Ali
    • Geomechanics and Engineering
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    • v.6 no.6
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    • pp.561-575
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    • 2014
  • Estimating seismic displacements has a great importance for foundations on or adjacent to slope surfaces. However, dynamic solution of the problem has received little attention by previous researchers. This paper presents a new analytical model to determine seismic displacements of the shallow foundations adjacent to slopes. For this purpose, a dynamic equilibrium equation is written for the foundation with failure wedge. Stiffness and damping at the sliding surface are considered variable and a simple method is proposed for its estimation. Finally, for different failure surfaces, the calculated dynamic displacement and the surfaces with maximum strain are selected as the critical failure surface. Analysis results are presented as curves for different slope angles and different foundation distances from edge of the slope and are then compared with the experimental studies and software results. The comparison shows that the proposed model is capable of estimating seismic displacement of the shallow foundations adjacent to slopes. Also, the results demonstrate that, with increased slope angle and decreased foundation distances from the slope edge, seismic displacement increases in a non-linear trend. With increasing the slope angle and failure wedge angle, maximum strain of failure wedge increases. In addition, effect of slope on foundation settlement could be neglected for the foundation distances over 3B to 5B.

Characteristics of Slope Failure induced by Typhoon and an Examination of a Standard Slope Inclination for Design (태풍에 의한 절개면 붕괴특성 연구 및 경사도 설계기준 검토)

  • Koo, Ho-Bon;Baek, Yong;Kwon, O-Il
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.117-122
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    • 2003
  • Every year in domestic slope failure caused by rainfall is happening frequently. Specially, causable failure accident by localized downpour accompanied when summer rainy season period and produces typhoon gets damage of large scale human life and property. Failure happened at slope of 121 places ranged whole country national highway by No.15 typhoon Rusa that strike whole country during 3 days from August 30, 2002. Slope failure that happen by typhoon are judged for major cause to effect of ground saturation and surface water by localized downpour. In this research, failure characteristic was analyzed to target 20 places attaining site investigation among failure slope. As a result, erosions by surface water was construed for major cause of failure and judged for direct relation in failure slope weathering and topography Also, result that analyze inclination of failure part, in the case of ripping rock, inclination of failure side is forming Incline of the lowest 40$^{\circ}$, because surface failure of depth 4m on or so scale happened, it is require that regulating plan gently design standard inclination of weathered rock and soil layer And it is considered that desirable preparation of design standard about measure that help smooth drainage of surface water and can restrain percolation in ground to reduce failure damage by rainfall.

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Review of Applicability of Analysis Method based on Case Study on Rainfall-Induced Rock Slope Failure (강우에 의한 암반사면 파괴 해석 사례 연구를 통한 해석방법 적용성 검토)

  • Jung, Jahe;Kim, Wooseok
    • The Journal of Engineering Geology
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    • v.27 no.3
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    • pp.267-274
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    • 2017
  • Behavior of rock mass depend on the mechanical properties of intact rock and geometrical property of discontinuity distributed in rock mass. In case of rock slope, particularly, location of slope failure surface and behavior after failure are changed due to discontinuities. In this study, two 3D slope stability analysis methods were developed for two different failure types which are circular failure and planar failure, considering that failure type of rock slope is dependent on scale of discontinuity which was then applied to real rock slope to review the applicability. In case of circular failure, stable condition was maintained in natural dry condition, which however became unstable when the moisture content of the surface was increased by rainfall. In case of planar failure, rock slope become more unstable comparing to dry condition which is attributable to decrease in friction angle of discontinuity surface due to rainfall. Viewing analysis result above, analysis method proved to have well incorporated the phenomenon occurred on real slope from the analysis result, demonstrating its applicability to reviewing the slope stability as well as to maintaining the slope.

Analysis of Influence Factors Related to Failure Characteristics of Excavated Slopes ; A Case of Southern Kyounggi Area along the Nat과l Road (절취 사면의 파괴 특성과 관련된 영향 요인 분석 ; 경기도 남부 국도 사례)

  • 김정환;윤운상;최재원
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.277-284
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    • 1999
  • This study describes the influence factors related to slope failure pattern and dimension in the southern Kyounggi area. Intrusive and metamorphic rocks are distributed in the study area. Geological condition, rainfall property and slope geometry are influence on slope failure characteristics in the study we& Geological factors related to slope failure are rock type, geological structure and weathering condition. Because of deep soil (RS-CW) depth of granite region, circular failure type is major failure pattern in granite region. Almost granite slopes with circular or surface failure pattern are failed during heavy rainfall season. But typical wedge failure type related to geological structure factor is a main failure pattern of metamorphic rock slope. Additionally failure dimension is influenced by geological factors and several factors, i.e. natural slope condition, failure type, rainfall intensity and etc. failure height/width ratio and thickness/length ratio of granite slope are 0.88 and 0.23. But the ratios of metamorphic rock slope are 1.36 and 0.19.

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Stability Analysis and Reinforcement of Large Excavated Slope considering Precipitation Infiltration in Rainy Season (강우침투로 인한 대절취사면의 붕괴안정성검토 및 대책)

  • Chun, Byung-Sik;Choi, Hyun-Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.4 no.1
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    • pp.101-110
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    • 2000
  • In case heavy rainfall is a key factor of slope failure, the failure zone is usually developed within the depth of 3~5m from the ground surface regardless of the location of the watertable. If rainfall is taken into consideration, it is general that the slope stability analysis is carried out under the assumption that the cut slope is saturated to the slope surface or the watertable elevates to a certain height so that ${\gamma}_{sat}$, the unit weight of saturated soil, is used. However, the analysis method mentioned above can't exactly simulate the variation of pore water pressure in the slope and yields different failure shape. The applicability of slope stability analysis method considering the distribution of pore water pressure within the slope with heavy rainfalls, was checked out after the stability analysis of a lage-scale cut slope in a highway construction site, where surface failure occurred with heavy rainfalls. An appropriate slope stabilization method is proposed on the base of the outcome of the analysis.

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Assumption of Failure Surface using Borehole Image Processing System in Failed Rock Slope (Borehole Image Processing System에 의한 붕괴사면의 활동면 추정)

  • Yoo Byung-Ok;Chung Hyung-Sik
    • 한국지구물리탐사학회:학술대회논문집
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    • 1999.08a
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    • pp.217-239
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    • 1999
  • Investigation methods of cut slope are conducted generally only geological surface survey to gain engineering geological data of cut slopes. These methods have many problems such as limitation of investigation for a special area. So geophysical investigations such as geotomography, seismic and electrical resistivity methods have been used to search for failure surface in potential failure slopes or failed slopes. But investigation method using the borehole camera is recently a used method and it is thought that this method is more reliable method than other investigation methods because of being able to see by the eyes. Therefore, this paper was conducted investigations of 4 boleholes and BIPS (Borehole Image Processing System) to search for potential sliding surfaces and was applied to obtain information of discontinuity on failed highway slope. As the results of BIPS, we could decide potential sliding surface in the slope and conducted to check slope stability. And decided slope stability measures.

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Numerical Analysis on Progressive Failure of Plane Slopes (평면 사면의 점진적 파괴에 관한 수치해석)

  • 송원경;권광수
    • Tunnel and Underground Space
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    • v.7 no.1
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    • pp.31-38
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    • 1997
  • Residual shear strength should be taken into consideration as well as peak one when analysing stability of slopes constituted by weathered rock or overconsolidated soils since such materials could be subjected to progressive failure mechanism. When landslide of a slope is related to progressive failure phenomenon, the failure might occur even though shear strength of the slope materials does not reach their residual shear strength over the whole slip surface. Therefore, stability of the slope concerned may be overstimated or underestimated when using only its peak or residual shear srength parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In parameters. Mechanical description for progressive failure phenomenon is given by Bjerrum(1967). In this study, his theory has been extended to estimate the distance of failed zone for a plane slope and the results calculated by this extended equatio has been compared with that obtained by numerical modelling using FLAC. In addition, stress state on the slip surface has been, in detail, analysed to understand failure mechanism when a limited progressive failure occurs. Effects of mechanical and hydraulic factors on progressive failure have also been analysed.

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