• The Journal of Engineering Geology
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• v.13 no.4
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• pp.491-496
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• 2003

본 기술은 암반사면 보강공법에서 철근보강재인 네일(Nail)에 원추형콘(철근 규격에 따라 기울기 $19~23^{\circ}$, 높이 40~45mm, 아랫변 65~70mm)을 일정한 간격으로 다수 장착하여 그라우트재와 원 지반까지 방사입체형으로 힘을 미치게 하는 암반사면 보강공법이다. 본 신기술 공법은 네일링 공사 시 원추형 콘을 장착, 삽입함으로서 부착력과 인발력을 증가시켜 비탈면 보강공사 시에 안전성을 높인 공법이다. 따라서 네일링공법을 사면붕괴 방지공사에 적극 활용할 수 있으므로 네일링 공법의 사용을 활성화 하며, 지진이나 지반변형 등 외력에 의한 사면붕괴를 사전에 방지할 수 있어 사면재해를 미연에 방지하는 효과가 있다. 또한 현재가지 네일링공법은 인발톤수가 적고 네일에 대한 신빙성 결여로 아주 적은 인발톤수를 필요로 하는 현장이외에는 사용을 기피하는 일이 많았다. 그러나 본 원추형 콘네일 공법은 어스앙카, 록앵커, 보강토공법, 지지말뚝공법, 옹벽 등에 대한 대체공법으로 이용할 수 있는 여건이 충족됨으로 사면보강재로서의 사용 확산이 기대된다.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.39-50
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• 2001

In this study, in order to investigate the effects of reinforcement length and vertical spacing on the factor of safety, the road embankment reinforced by geogrid was analyzed using RSS(Reinforced Slope Stability) program based on limit equilibrium analysis. The result by computer analysis showed that the factor of safety for reinforced slope increased with increasing length of reinforcement and with decreasing vertical spacing of reinforcement up to certain limit. Also, numerical analysis by FLAC was performed on reinforced slope to evaluate the horizontal displacement, horizontal stress, and distribution of tensile forces of reinforcements in the cases of several reinforcement length. The results of analysis showed that the critical failure mode was toe failure or slope failure and the effect by the additional reinforcement length on the slope stability was negligible under stabilized condition.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.49-59
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• 2013

Heavy rainfall intensity may cause shallow slope failures and debris flow by rill erosion and scour on land surface. The paper represents the difference between native soil (weathered soil) and reinforced soil, which is mixed by hardening agent with flyash as main material, for investigating experimental findings of rill erosion and erosion. Results obtained from artificial rainfall simulator show that erosion rate of reinforced soil mixed with hardening agent is reduced by 20% because an amount of eroded soil on slope surface is inversely proportional to the increase of soil strength. For example, rainfall of 45mm (at the elapsed time of 25mins in rainfall intensity of 110mm/hr) triggers rill erosion on native soil surface, but the rill erosion on reinforced soil surface does not even occur at 330mm rainfall (at the elapsed time of 3hrs in rainfall intensity of 110mm/hr). As a result of slope stability analysis, it was found that the construction method for reinforced soil surface would be more economical, easy and fast construction technology than conventional reinforcement method.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10b
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• pp.44-58
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• 2001

FRP(Fiberglass Reinforced Plastic)관을 이용한 사면보강은 천공 후 그라우트재에 압력을 가하여 그라우트재의 천공홀 충전뿐만 아니라 지반으로의 침투주입 효과를 일으켜, 전체적인 보강력 증대를 기대하는 공법이다. 이런 특성을 설계에 반영하기 위해서는 구조재료인 FRP관 자체에 의한 지반보강효과 뿐만 아니라 그라우팅에 따른 지반강도의 증진효과를 정량적으로 평가하는 것이 선행되어야 하나 아직까지는 이에 대한 연구가 부족한 실정이다. 따라서 대상지반을 토사와 암반사면으로 구분하여 각각의 보강효과를 확인하고자 현장시험 및 수치해석을 실시하였으며, 이로부터 지반종류에 따른 보강특성과 합리적인 설계를 위한 설계인자를 추출하고자 하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.109-116
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• 2010

Infiltration and the rising level of groundwater caused by rainfall are a major cause of the landslide and sliding. In order to secure the safety factor of slope, the slope stabilization and reinforcement works are used to enhance consistency. Nailing, Slope Drainage method and the surface vegetation measures can be simultaneously applied in the Mass Nail method, which is also environmental friendly reinforcement method. To demonstrate the reinforcement effect of a strengthened slope by Mass Nail, the changes in water contents by rainfall were considered while performing Scale Model Test. As a result, safety factor of reinforced slope was about 1.4~2.3 times increased on the unstrength slope. In the case of increasing water content 10% to 22%, The maximum stress was reduced to 12%~24% at the average rate of 18% on the unstrength slope and the reinforced slope by the Mass Nail Method was reduced to 4%~23% at the average rate of 14%.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.39-52
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• 2011

This paper describes a new numerical analysis technique in stability analysis for a slope reinforced with pressure grouted soil nails. The installing effect of pressure grouted soil nails can be simulated in this method. Shear strength reduction method associated with finite element method is used for slope stability analysis. Factors of safety for a slope reinforced with pressure grouted soil nails are compared with those for a natural slope and a slope reinforced with gravity grouted soil nails in order to investigate their reinforcing effects. More than 50% increase in the factor of safety is obtained when the slope is reinforced with pressure grouted soil nails compared to the one with gravity grouted soil nails. The reinforcing effects of pressure grouted soil nails become obvious with increase in their length. The reinforcing mechanism of the pressure grouted soil nails for the slope stability can be explained by the slope failure surface expanding gradually toward the backfill. The increased stability of the slope reinforced with pressure grouted soil nails results mainly from their improved pull-out resistance.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.297-301
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• 2008

매년 집중호우로 인하여 사면붕괴 및 산사태가 발생하고 있다. 사면 붕괴의 원인은 단순히 한가지의 요소에 의하여 붕괴되지 않고 다양한 요인이 중첩되어 발생된다. 이런 요인들을 사전에 파악하여 붕괴원인을 규명하고 적절한 사면 보강 방안 및 설계를 실시하여야 할 것으로 생각된다. 본 고는 사면붕괴후 설계 보강방안에 대한 자료를 수집하고 분석을 실시하였다. 사면붕괴의 요인으로 생각하는 대표적인 사례를 열거하였다. 사면붕괴로 인해 발생하는 피해를 저감하고 재차 사면 붕괴를 방지하기 위하여 도움이 되었으면 한다.

• The Journal of Engineering Geology
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• v.4 no.3
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• pp.343-356
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• 1994

When most of the industry and social indirect facilities such as the large structure, power plant or road, rail-road are constructed, the new slope may lead to the slope failure. The failure models for slopes have been developed by using the results of in-situ and laboratory tests to investigate the mechanisms and types of the slope failure. The safety factor of a slope may be obtained based on the proposed model and the slope can be reinforced to meet the design criteria. The slope should be reinforced by using the optimum model that properly reflects the site condition, the method of reinforcement includes the increased safety factor either by decreasing a slope angle or by reinforcing the slope.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.189-199
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• 2006

This paper presents a field study of the stability of slope collapsed during road construction and proposes a reasonable countermeasure if the current slope is unstable. As a result of slope investigation, it was found that the slope includes five tension cracks and the sliding surface is started from the tension crack and propagated the surface soil layer through weathered rock layer. The slope stability analyses are conducted in case of dry and rainfall seasons. The results indicate that the slope is unstable status. A reinforcement method of slope failure should be selected according to the scale of failure. That is, the scale of slope failure, which is classified small, middle and large size determines the reinforcement method of slope. Since the slope interested in this study is large size failure slope, the reinforcement method to control slope failure is selected stabilizing piles, and seed spray and drainage of surface waterare also selected to remain the factor of safety. The SLOPILE (Ver. 3.0) program is applied in order to do stability analysis of slope reinforced by piles. As the result of analysis, the slope reinforced by a row of piles shows the stable state. It is clearly confirmed that the stabilizing of piles can improve the stability of slope.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.107-116
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• 2005

Generally, when the stability of the geosynthetic reinforced soil slopes is analyzed, the required tensile forces of each reinforcement layers are calculated from total reinforcement forces which are necessary to retain the equilibrium state of slip mass in which the slip surfaces are assumed to be a linear or bilinear. It is assumed that the reinforcement forces are increased or constant with depth. However, according to the instrumented field data and laboratory model test results, the maximum tensile strain of reinforcement in a reinforced soil slope is developed in a certain elevation, not a bottom of the slope. In the concept of reinforced soil, postulated failure surfaces are the traces of the position in which the reinforcement tensile forces are maximum in the layer, and the reinforcement tensile forces are related to the stress state on the postulated failure surface. Therefore, in this study, based on the distribution of normal stress on the slip surface, a new method for the evaluation of required tensile forces is suggested and a number of the instrumented field data are analyzed by newly suggested method. As a result, it is shown that the newly suggested method produces relatively accurate reinforcement tension forces.