• 한국지반신소재학회논문집
• /
• 제15권2호
• /
• pp.13-24
• /
• 2016

얕은 토층의 무한사면 파괴가 예상되는 지역에서 안전율 계산에 영향을 주는 지역적 특징인 뿌리점착력을 고려하지 않은 무한사면 안전율은 뿌리점착력을 적용한 무한사면 안전율 보다 낮은 수치로 해석되는 경향이 있다. 따라서 합리적인 무한사면의 안전율을 계산하기 위하여 지역적 특징을 반영한 안전율 해석이 필요하다. 본 연구에서는 수목의 뿌리와 수관밀도가 무한사면의 안전율에 미치는 영향을 분석하기 위하여 기존 무한사면 안정해석 방법에 수관밀도를 고려한 뿌리 점착력 이론을 적용하여 안전율의 변화를 비교 분석하였다. 해석결과 뿌리점착력의 효과로 인하여 안전율이 증가하지만, 사면의 경사에 따라서 안전율의 증가량이 다른 것으로 분석 되었으며, 뿌리점착력의 보강 효과는 완만한 경사의 사면일수록 커지는 것으로 나타났다.

• Geomechanics and Engineering
• /
• 제30권2호
• /
• pp.123-138
• /
• 2022

Present study computes the ultimate bearing capacity of an embedded strip footing situated on the rock slope subjected to seismic loading. Influences of embedment depth of strip footing, horizontal seismic acceleration coefficient, rock slope angle, Geological Strength Index, normalized uniaxial compressive strength of rock mass, disturbance factor, and Hoek-Brown material constant are studied in detail. To perform the analysis, the lower bound finite element limit analysis method in combination with the semidefinite programming is utilized. From the results of the present study, it can be found that the magnitude of the bearing capacity factor reduces quite substantially with an increment in the seismic loading. In addition, with the increment in slope angle, further reduction in the value of the bearing capacity factor is observed. On the other hand, with an increment in the embedment depth, an increment in the value of the bearing capacity factor is found. Stress contours are presented to describe the combined failure mechanism of the footing-rock slope system in the presence of static as well as seismic loadings for the different embedment depths.

• Geomechanics and Engineering
• /
• 제28권1호
• /
• pp.77-87
• /
• 2022

Many geotechnical analyses require the investigation of water flow within partially saturated soil zone to incorporate the effect of climatic conditions. It is widely understood that the hydraulic properties of the partially saturated soil should be included in the transient seepage analyses. However, the characteristics of dual porosity soils with dual-mode water retention curve are normally modelled using single-mode mathematical equation for simplification of the analysis. In reality, the rainwater flow can be affected significantly by the dual-mode hydraulic properties of the soil. This paper presents the variations of safety factor for dual porosity soil slope with dual-mode water retention curve and dual-mode unsaturated permeability. This paper includes the development of the new dual-mode unsaturated permeability to represent the characteristics of soil with the dual-mode water retention curve. The finite element analyses were conducted to examine the role of dual-mode water retention curve and dual-mode unsaturated permeability on the variations of safety factor under rainfall loading. The results indicate that the safety factor variations of dual porosity soil slope modelled using the dual-mode water retention curve and the unsaturated permeability equation are lower than those of dual porosity slope modelled using single-mode water retention curve and unsaturated permeability equations.

• 한국지반공학회논문집
• /
• 제24권11호
• /
• pp.5-16
• /
• 2008

국내현장에서 수집된 9개소 안벽구조물의 측방이동 실측자료에 대한 분석을 통해 연약지반상 안벽의 측방이동을 평가할 수 있는 방안을 제안한다. 잔교식 안벽 등과 같이 말뚝이 시공되어 있는 호안 안벽구조물의 측방이동 가능성을 효과적으로 판정하기 위해서는 말뚝의 사면안정 기여효과를 반영한 사면안정해석을 수행해야 하며, 측방이동을 방지하기 위해서는 말뚝의 사면안정효과 고려시 최소 1.6 이상의 사면안전율을 확보하여야 한다. 한편, 케이슨식 안벽과 같이 말뚝이 시공되지 않은 연약지반상 호안구조물의 안정을 위한 소요 사면안전율은 1.3 이상으로 규정하는 것이 바람직하다.

• 농업과학연구
• /
• 제39권1호
• /
• pp.97-110
• /
• 2012

This study was carried out for safety evaluation, the practical application and improvement of design method of the agricultural reservoir embankment according to backside extension. Seepage analysis, slope stability analysis and finite element analysis were performed for steady state and transient conditions. Also, the pore water pressure, seepage quantity, safety factor and stress-strain behavior according to high water level and rapid drawdown were compared and analyzed. The pore water pressure at contact region between backside extension and old embankment was kept high after rapid drawdown. Therefore, backside extension is recommended that design method is required to be improved and reinforced more than the others raising embankment. The hydraulic gradients before and after backside extension showed high value at the base of the core, but they showed stable state at the upstream slope and downstream slope. The seepage quantity per 1 day and the leakage per 100 m for the steady state and transient conditions appeared to be safe against the piping. The safety factor of slope stability showed high at the steady state, and transient conditions did not show differences depending on the rapid drawdown. The safety factor was appeared high at the upstream slope before backside extension and downstream slope after extension. The excess pore water pressure for steady state and transient conditions showed negative(-) at the upstream slope, it was small at the downstream slope. The mean effective stress (p') showed high at the base of the core and to be wild distribution after the extension. The displacement after extension showed 0.02-0.06 m in the upstream slope, the maximum shear strain after extension was smaller than that before extension.

• 지질공학
• /
• 제15권1호
• /
• pp.9-17
• /
• 2005

본 연구는 전라남도 장성군 일대의 석회암지대에서 강우로 인해 파괴된 절개사면을 대상으로 시료를 채취하여 물리적ㆍ역학적 특성을 파악하고 강우로 인한 사면 안정 해석을 통해 사면구배의 변화에 따른 안전율의 변화를 규명하였다. 연구지역 석회암 풍화토는 석영, 정장석, 깁사이트, 침철석 등으로 구성되어 있고 비중은 2.73, 통일분류상 SC에 해당되며 모암에서 풍화가 진행되면서 칼슘성분이 현저하게 감소하였다. 투수계 수는 2.56×10/sup -4/ cm/ sec 로서 실트 성 점토의 투수계수와 비슷한 값을 보였고 전단시험결과 불포화토에서 포화토로 변할수록 점착력은 3.0 t/㎡에서 0.72 t/㎡로 현저하게 줄어들며 내부마찰각 Φ 값도 감소하는 경향을 보였다. 강우로 인한 사면안정 해석시 강우강도를 고려한 침투심도를 구하는 것이 합리적이며 사면안정해석결과 침투심도가 클수록 사면의 안전율은 낮아져서 불안정하게 되고 침윤선을 고려한 절토사면의 최소안전율 1.5와 비교 시 강우를 고려한 석회암 풍화토의 절토사면 구배는 1 ： 1.2이상 되어야 안전율을 만족하는 것으로 나타났다. 또한, 불포화토에서 포화토로 변할수록 점착력의 감소는 사면의 안전율감소에 많은 영향을 미침을 알 수 있었다.

• 대한지질공학회:학술대회논문집
• /
• 대한지질공학회 2003년도 정기총회 및 학술발표회
• /
• pp.153-158
• /
• 2003

Traditionally, the statistical methods has been used to analyze the relationship between landslide occurrence and related factors(soil depth, soil strength, slope angle, vegetation, etc.) in GIS technique. However, the method have no mechanical meaning. Therefore, the mechanical model is suggested in this research. The method analyzes the mechanical equilibrium of a potential slide block and then calculates a slope safety factor. Since this method is able to consider the balance of forces applied to the slope and is a more reasonable method for an individual site. In this research, the spatial data is obtained, managed and analyzed using GIS technique, and the infinite slope model is used to evaluate factor of safety and analyze the slope stability.

• 한국추진공학회지
• /
• 제3권3호
• /
• pp.16-24
• /
• 1999

다른 윗면 경사각을 가진 사다리꼴 휜 들에 대한 성능 해석이 3차원 해석적 방법에 의하여 조사된다. 단지 경사요소 값을 조정함으로써 한가지 식으로 다른 경사각을 가진 사다리꼴 횐 들을 해석할 수 있는 것이 보여진다. 나머지 변수들을 임의로 고정하였을 때 휜들의 성능들이 무차원 휜 길이, 휜 폭, Biot 수 그리고 경사요소에 대한 함수로 보여진다. 하나의 결과로서 Biot 수가 0.1 이하의 경우에서는 Biot 수, 무차원 휜 폭 그리고 경사요소가 감소함에 따라, 반면에 무차원 길이가 증가함에 따라 휜 유용도는 증가 하나 더 큰 Biot 수에서는(즉, Bi=0.3) 유용도에 대한 횐 형상의 효과의 변화 경향은 다소간 불규칙적이다.

• Geomechanics and Engineering
• /
• 제31권5호
• /
• pp.453-460
• /
• 2022

It is essential for geotechnical engineers to conduct studies and make predictions about the stability of slopes, since collapse of a slope may result in catastrophic events. The Gaussian process regression (GPR) approach was carried out for the purpose of predicting the factor of safety (FOS) of the slopes in the study that was presented here. The model makes use of a total of 327 slope cases from Iran, each of which has a unique combination of geometric and shear strength parameters that were analyzed by PLAXIS software in order to determine their FOS. The K-fold (K = 5) technique of cross-validation (CV) was used in order to conduct an analysis of the accuracy of the models' predictions. In conclusion, the GPR model showed excellent ability in the prediction of FOS of slope stability, with an R² value of 0.8355, RMSE value of 0.1372, and MAPE value of 6.6389%, respectively. According to the results of the sensitivity analysis, the characteristics (friction angle) and (unit weight) are, in descending order, the most effective, the next most effective, and the least effective parameters for determining slope stability.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.736-744
• /
• 2009

The abrupt failure of slope caused by a concentrated rainfall would be a disaster in this country. Specially, the soil slope may be collapsed by the rainfall seepage, however, there is not much information for the mechanism of slope failure during rainfall. As analyzing the stability of slope by rainfall, the conventional method is to put the ground-water level on the surface of slope. However, it may provide the over-reinforcement for the slope stability. Futhermore, although over-reinforcement for the slope was fulfilled, the possibility of potential slope failure still exists. In this study, the slope stability by the conventional design method and the causes of unstable slope during rainfall were investigated. To analyze the slope stability by rainfall, the computer program SEEP/W for the analysis of seepage was used. As changing the intensity and duration of rainfall in SEEP/W, the analysis were performed. After completion of analysis, the porewater pressure data from SEEP/W was applied to SLOPE/W. As a results of this analysis, it is not reasonable that the groundwater level is going up to the surface of slope during rainfall. Therefore, the conventional reinforcement for the slope stability is not obvious to satisfy the criterion safety factor during rainfall. The reasonable counterplan is to install drainage hole on the surface of slope in order to prevent erosion and debris flow.