• Proceedings of the Korean Geotechical Society Conference
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• 2001.10b
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• pp.78-97
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• 2001

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.517-528
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• 2009

Statistical analyses of cut-slope stability were performed over approximately 5.7 km section along the National road No. 25, which cross-cuts in NW-SE direction the Cheongwon and Boeun-Gun area, Chungbuk. A measure of slope-stability was established by using direct reinforcement and indirect protection methods in whole section. Orientations(dip/dip direction) of the slopes, foliations(bedding), cleavages and joints were measured in total of 30 slope sites. The results analyzed using stereographic projection indicate that major directions of the slopes come out predominantly in three directions: 1) $58^{\circ}/095^{\circ}$, 2) $60^{\circ}/296^{\circ}$ and 3) $59^{\circ}/212^{\circ}$. In analyses of dip direction and frequency of cut-slopes established by reinforcement and protection methods, slopes with dip direction of $80-120^{\circ}$ and $280-320^{\circ}$ mostly occur. However, slopes with dip direction of $0-80^{\circ}$(N and NW) and $120-160^{\circ}$(SE) are not distributed in the study area. Failure aspects were analyzed for three major directions of the slopes, respectively. The results of failure aspects analyzed indicate that slopes in the study area could generate various failures as the results of intersection and/or intersection combination among joints, foliations(bedding) and cleavages. However, possibility of failure in a slope of major direction No. 3 is statistically very low because of low frequency in total number of slopes with the direction and of formation of small scale-slopes geographically, although the slope might generate all aspects of failure-modes.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.405-414
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• 2008

When we evaluate slope stability, we regard the slope homogeneous and evaluate slope stability at the most dangerous portion of slope. However, since conditions and properties of rock mass/soil are different from one location to another within a single slope, slope stability evaluated by current concept can not represent slope correctly. This also result in over-reinforcement at the portion where reinforcement is not necessary. In order to solve these problems, we suggest a cell unit evaluation method in which we apply small rectangular cells in a slope and regard each cell as a single slope. In this method, slopes are classified into soil slope and rock slope depending on materials. Strength of rock, volumetric joint count, spacing of joints, condition of joints, ground water condition and so on are examined and SMR and condition index values are calculated. Finally, all data and results are presented as contour maps. We apply the cell unit evaluation method into 3 cut slopes. SMR values estimated by the new method are larger than those by current concept at most portions of slope, indicating that the new method suggested by this research represent slope stability more correctly than methods which were used. This method will prevent over-reinforcement at the portion of slope where reinforcement is not necessary.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.55-60
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• 2008

This paper presents how the load transfer mechanism of the ground anchor affects on the stability analysis of anchored slope. The finite element analysis and the conventional limit equilibrium analysis on the anchored slope were performed and compared. The limit equilibrium analysis of the anchored slope is widely used in design practice due to the easiness of the analysis. However, the load transfer mechanism is not considered properly for the analysis. When the failure surface passes through the bonded length of an anchor, the anchor load is disregarded and the factor of safety for the anchored slope is smaller than it should be. In this study, the load transfer distribution was incorporated into the limit equilibrium stability analysis of the anchored slope and the results were compared with those of finite element analysis.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.31-40
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• 2009

This paper presents a new approach of risk evaluation method for the reinforced slopes. In order to perform this study, the existing stability and risk evaluation methods are reviewed and analysed in terms of rainfall, ground condition, and drain conditions. According to the characteristic of the reinforced slopes improved by internal and external reinforcement, the nineteen influence factors are determined in order to develop new risk analysis model based on 'Interaction matrix' approach suggested by Hudson (1991). Using new approach of slope risk analysis model, the weighting values for interaction factors are analysed and determined. Based on new slope risk evaluation approach, the slope risk index, namely SRI (Slope Risk Index) is developed in this study to apply the evaluation of the reinforced slopes. In order to verify the SRI, a total of 15 cases are studied and analysed. The analysed results are compared and evaluated. According to the results, it is deduced that new slope risk evaluation method (SRI approach) IS very useful and practically a reliable method to evaluate the existing slopes.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.207-215
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• 2004

In this study, the upper bound theory is applied to a reinforced slope to develop an limit state analysis method. As processing of this upper bound theory in formulating finite element, the basic idea of numerical method can be obtained from a macroscopic point of view with an anisotropic homogeneous material. The reinforced soil strength reliability depends on properties of reinforcements which consist of the interaction of interfaces between back fill and reinforcements. Both soil's mechanical property and overall behaviour of reinforced soil can be controlled via arranging geometry and relative proportions of reinforced soil. Therefore, the upper bound theory can not only predict the particular limit state action of reinforced soil slope but also is efficiently able to estimate the local plastic failure.

• The Journal of Engineering Geology
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• v.23 no.3
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• pp.283-292
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• 2013

A calcareous rock slope failed during excavation of the slope for construction of a tunnel entrance. The slope is located at the construction site for widening highway in Yeongwol, Korea. Field surveys, laboratory tests, and numerical analyses were performed to determine the reason for the slope failure. The numerical analysis revealed that the safety factor of the slope before construction of the entrance was less than 1, and that this decreased after construction. After construction of the entrance, the sliding zone of the slope increased and slope stability decreased because the shear strain and plastic zone in the slope over the tunnel entrance showed an increase relative to the lower part of the slope. To enhance the stability of the slope for construction of the tunnel entrance, countermeasures such as rock bolts, rock anchors, and FRP (Fiber glass Reinforced Plastic) grouting were adopted in light of the field conditions. Serial field monitoring performed to confirm the reinforcing effects of the adopted countermeasures revealed a small amount of horizontal deformation of the slope soils, most of the elastic deformation that can regain its former value. In addition, the axial forces of the rock bolt and anchor were more strongly affected by slope excavation during construction of the tunnel entrance than by tunnel excavation or the rainy season, and the axial forces tended to converge after excavation of the tunnel. Therefore, we can confirm that the slope is currently safe.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.343-355
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• 2021

Agricultural reservoirs seek human convenience by supplying agricultural water and providing flood damage effects and rest areas at the same time, but preventing them from aging reservoirs and earthquakes is important. The safety of levees is influenced by field material properties such as soil parameter values of the granular materials that make up the levees, but since precision safety diagnosis or general literature values are diverted, the final safety factors are limited to material properties alone. Since safety factors are determined by physical characteristic values and embankment shapes and have a significant impact on safety factors, accurate contemplation is required when examining reinforced cross sections. Therefore, this study analyzed the case of reasonable and economical reinforcement intersections when designing '◯◯reservoir' in Goheung-geun, Jeollanam-do using the GEP-SLOPE program to enable rational economic design of reinforcement intersections through repeated reviews. As a result of reducing and analyzing the first, second, and third seismic reinforcement of the levees, it was confirmed that the safety ratio was secured even with a significantly smaller amount of reinforcement than the first, second, and lower slopes by obtaining design standards of 1.20. In addition, when determining all seismic reinforcement cross-sectional shapes, it was confirmed that the shape that reinforces only the lower side rather than the upper side of the slope and the entire slope was economical with minimized cross-sectional reinforcement.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.407-418
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• 2003

It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure surface resulting from weathering effect and other factors. The FBG(Fiber Bragg Crating) sensor system is used to estimate the correlations between the soil temperature and the slope behavior, and to find a failure surface in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution of the reinforcing materials in an active zone by analyzing the data from the in-situ measurement so that the possible failure surface should be well defined based on the correlation. The zone of high temperature fluctuation can be regarded as one of the possible failure surface due to the weathering effect while the constant temperature depth of the ground, if exists, would not be relatively affected by the weathering process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2794-2802
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• 2009

Soil nailing method is widely used in reinforcing slopes and excavating earth. The analysis of nail-reinforced slopes, generally require complicated computer programs. The purpose of this paper is suggest, Soil stability Chart for nailed slopes which are very useful for pre-design, rapidly design, and final check. Three slope types, three nail lengths and three nail angles are selected for the stability analysis by using limit equilibrium method form Bishop and French. From the above results, this study propose the reinforced design charts for examine the necessity of reinforcement can be examined. The suggested stability chart and Taylor's Slope Stability Chart, showed similar safety factors. This Soil Nailing design charts can provide the solutions for necessity of reinforcement, economical of nail's length ratio and installation angle as well.