• Geomechanics and Engineering
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• 제23권5호
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• pp.481-491
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• 2020

Piles installed in row(s) are used as an effective technique to improve the stability of soil slopes. The analysis of pile-stabilized slopes require a reliable prediction of lateral resistance offered by the piles. In this work, an analytical solution is developed to estimate the lateral resistance offered by the stabilizing piles in sand and c - 𝜙 soil slopes considering soil arching phenomenon. The soil arching in both horizontal direction (between the neighboring piles) and vertical direction (in the active wedge in front of the pile row) are studied and their effects are incorporated in the proposed model. The shape of soil arch is assumed to be circular and principal stress trajectories are defined separately for both modes of arching. Experimental and numerical studies found in literature were used to validate the proposed method. A detailed parametric analysis was performed to study the influence of pile diameter, center-to-center spacing, slope angle and angle of internal friction on the lateral pile resistance.

• Geomechanics and Engineering
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• 제13권4호
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• pp.653-669
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• 2017

By increase in the population and consequently constructions, new structures may be built in vicinity of the soil slopes. Such structures can be regarded as an extra surcharge on the slopes. The intensity and location of the surcharge affects the displacements of the slopes. Few researchers have studied the effect of surcharge on displacements of soil slopes. In this research, using limit analysis method and upper bound theory with non-associated flow rule, displacements of soil slopes in vicinity of a surcharge has been estimated. The authors have improved the technique previously proposed by them and a new formulation is suggested for calculating the permanent displacements of the soil slope in presence of a surcharge for two failure modes, rotational and transitional. A comparison has also been made between the two mentioned modes for various conditions of surcharge and slope. The conditions resulting in the rotational mode to be more critical than the transitional mode have been investigated. Also, the effects of surcharge's intensity, location of surcharge as well as the soil properties have been investigated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.862-869
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• 2005

This study examined 233 cut slopes in Gyeongnam region; evaluated hazards and slope conditions involved in the slope; and determined the priority order for reinforcement. The conclusions are summarized in the following. (1) The slopes that need reinforcement or maintenance are 153, accounting for 65.6% of the entire slopes. Slopes with a length of $0{\sim}200m$ account for 70.9%; slopes with a height of $10{\sim}20m$ account for over 50%. (2) Slopes with slope of more than 1:0.5 account for 70.9% of the entire slopes. The steepness of the slope is owing to more rock slopes than soil slopes. (3) The percentages of rock slopes, soil slopes, complex slopes mixed with rocks and soil, and slopes comprised of igneous rocks are 54.4%, 24.9%, 20.7%, and 54.1%, respectively. (4) In the rock area occurred cave-in, plain failure, wedge failure, and overturning failure, in order. Slopes with volcanic rocks are the most unstable, while sedimentary rocks and metamorphic rocks are relatively stable. (5) When the slope height is over 20m, low grade slopes are more than 80%; leading to the conclusion that the higher the slope height is, the more unstable the slope is.

• 한국환경복원기술학회지
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• 제19권2호
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• pp.121-135
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• 2016

The present study is an analysis of the monitoring results of the four areas that underwent the experimental construction of Straw-net+seedspray, Vegetation media spray method(t=2cm), and Vegetation media spray method(t=3cm), with the purpose of selecting the adequate revegetation of cutting slopes in weathered granite soil. Cutting slopes are mostly designed in the Straw-net+seedspray method, but since weathered granite soil slopes tend to have an infertile soil quality that runs down, it is difficult for seed germination and growth. It is difficult to apply Straw-net+seedspray to weathered granite soil slopes considering the germination rate and coverage rate of the Straw-net+seedspray method, which accompanies erosion and scouring. The final conclusions are summarized as follows. First, Straw-net+seedspray has difficulty recruiting plants to infertile weathered granite soil, which results in a lower coverage rate and fewer species, so it is not adequate construction method. Second, Vegetation spraying methods with wet media are more advantageous in early revegetation. The wet construction methods are faster than the dry construction methods in terms of early germination and its early growth are more excellent. Third, when constructing Vegetation spray methods with dry media, it were more advantageous if the thickness was thicker. When the soil-media is thicker, the soil is resilient to droughts, so the thickness must be flexibly applied according to the soil quality and slant of the weathered granite soil slope. The present study is a monitoring result for some areas of Gangwon-do, so its results may differ from other areas.

• Geomechanics and Engineering
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• 제18권3호
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• pp.315-328
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• 2019

This paper presents an investigation on bearing capacity, load-settlement behavior and safety factor of rock-soil slopes reinforced using geogrid-box method (GBM). To this end, small-scale laboratory studies were carried out to study the load-settlement response of a circular footing resting on unreinforced and reinforced rock-soil slopes. Several parameters including unit weight of rock-soil materials (loose- and dense-packing modes), slope height, location of footing relative to the slope crest, and geogrid tensile strength were studied. A series of finite element analysis were conducted using ABAQUS software to predict the bearing capacity behavior of slopes. Limit equilibrium and finite element analysis were also performed using commercially available software SLIDE and ABAQUS, respectively to calculate the safety factor. It was found that stabilization of rock-soil slopes using GBM significantly improves the bearing capacity and settlement behavior of slopes. It was established that, the displacement contours in the dense-packing mode distribute in a broader and deeper area as compared with the loose-packing mode, which results in higher ultimate bearing load. Moreover, it was found that in the loose-packing mode an increase in the vertical pressure load is accompanied with an increase in the soil settlement, while in the dense-packing mode the load-settlement curves show a pronounced peak. Comparison of bearing capacity ratios for the dense- and loose-packing modes demonstrated that the maximum benefit of GBM is achieved for rock-soil slopes in loose-packing mode. It was also found that by increasing the slope height, both the initial stiffness and the bearing load decreases. The results indicated a significant increase in the ultimate bearing load as the distance of the footing to the slope crest increases. For all the cases, a good agreement between the laboratory and numerical results was observed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.1009-1019
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• 2009

Soil nailing method is widely used in reinforcing slopes and excavating earth. The analysis of nail-reinforced slopes, in order to determine the economical length ratio and nail angle, complicated analytical need to be applied by means of computer programs. Therefor this suggested Soil stability Chart for nailed slopes which may be very useful for pre-design, rapidly design, and final check. Three slope types, three nail length and three nail angles are selected for the stability analysis by using limit equilibrium method of Bishop and French Method. From the above results, this study propose the slope reinforced design charts for dry season and rainy season. This proposed reinforced design charts can check dry season as well as rainy season, also these charts can provide reinforcing requirement, soil nail's economical length ratio and nail angle as well.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.502-513
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• 2007

This paper describes the rainfall-induced slope failures caused by infiltration due to prolonged rainfall. The emphasis was on quantifying the effect of fine-grained contents which are influencing on the infiltration rate in the wetting front of initially unsaturated slopes during rainfall. Suction tests by tensiometer were performed for five mixture specimens with varying fine-grained contents and then, numerical analyses for the stability of unsaturated slopes are carried out for different relative densities and mixture portions based on the soil water characteristic curves obtained by GCTS pressure plate. It is shown that the fines are highly influenced on wetting front suction of unsaturated soil slopes. Based on the results, it is found that until 15% fine content is the limit showing different wetting front suction, beyond which the wetting band depth do not affect considerably the stability of unsaturated slopes.

• 한국지반공학회논문집
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• 제23권3호
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• pp.101-109
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• 2007

국내 풍화토사면의 경우 순수 균질 사면보다는 대부분 점토 및 세립분이 섞인 비균질 상태로 존재하며 이러한 함유비율은 풍화도 및 지역에 따라 다르다. 따라서 세립분함량 변화에 따른 불포화사면에의 분석을 위해, 화강풍화토(SW)에 일정비율의 세립분(CH)을 섞어 성형한 시료를 통해 GCTS pressure plates을 이용한 함수특성곡선 실험을 수행하였다. 실험 및 침투해석결과 강우지속시간에 따른 포화깊이의 증가율은 세립분이 증가할수록 또한 상대밀도가 증가할수록 작아졌다. 또한 침투해석과 포화 및 불포화강도정수를 이용한 사면 안정성 해석결과(SLOPE/W), 전반적으로 세립분함량 $10\sim15%$의 범위까지는 침투깊이 증가에 따른 흡수력 변화가 안전율에 지대한 영향을 미치는 반면 이를 초과하는 경우(>15%)에는 오히려 세립분함량 증가에 따른 강도정수의 변화가 크게 영향을 미침을 알 수 있었다.

• 한국산림과학회지
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• 제29권1호
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• pp.54-101
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• 1976

우리나라 요사방지(要砂防地)에서의 토양침식(土壤侵蝕)의 경과(經過)와 기구(機構)를 토양침식(土壤侵蝕)에 작용(作用)하는 몇가지 주(主) 요인(要因), 즉(即) 토성(土性)(조토(粗土), 세토(細土)), 사면경사도(斜面傾斜度)($10^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$), 강우강도(降雨强度)((50, 75, 100mm/hr), 사면피복방법(斜面被覆方法)(무피복(無被覆), 거적덮기, 새풀덮기, 토양침식방지액제피복(土壤侵蝕防止液濟被覆), 그리고 식생밀도(植生密度)(소(疎), 중(中), 밀(密))등(等)에 관련(關聯)시켜 실험분석(實驗分析)하여 침수(侵蝕)의 내용(內容)을 수량적(數量的)으로 밝히고 각(各) 요인간(要因間)의 상호작용(相互作用)과 영향도(影響度)를 구명(究明)하는 동시(同時)에, 또한 토양침식(土壤侵蝕)과 표면유출(表面流出)에 대(對)한 피복처리(被覆處理)의 효과(効果)를 분석(分析)하여 산지사방공법개발(山地砂防工法開發)에 필요(必要)한 기초자료(基礎資料)를 제공(提供)하고저 인공강우장치(人工降雨裝置)를 이용(利用)한 4개조(個組)의 실내실험(室內實驗)과 자연강우하(自然降雨下)에서 1개조(個組)의 야외실험(野外實驗)을 수행(遂行)하여 연구(硏究)한 결과(結果)는 다음과 같이 요약(要約)될 수 있다. 1. 실험요인(實驗要因)과 표면유출율(表面流出率) 표면유출량(表面流出量)은 토성(土性), 사면경사도(斜面傾斜度), 강우강도(降雨强度), 사면피복처리(斜面被覆處理)에 따라서 그 차이(差異)가 많았다. 자연강우하(自然降雨下)의 야외실험무피복사면(野外實驗無被覆斜面)에서는 경사도(傾斜度)에 따라서 다르지만 대체(大體)로 조토(粗土)에서 약(約) 24.7~27.3%, 세토(細土)에서 약(約) 26.0~28.7%이었으며, 피복사면(被覆斜面)에서는 거적덮기 조토(粗土)에서 약(約) 14.0~15.7%,세토(細土)에서 약(約) 15.0~16.4%이었으며, 토양침식방지액제피복(土壤侵蝕防止液濟被覆) 조토(粗土)에서 약(約) 7.9~8.7%, 세토(細土)에서 약(約) 8.6~9.1%이었고, 새풀덮기 조토(粗土)에서 약(約) 5.6~6.9%, 세토(細土)에서 약(約) 6.0~7.2%로서, 일반적(一般的)으로 조토(粗土)에 비(比)하여 세토(細土)에서 약(約) 1~2%가 많았다. 그리고 인공강우(人工降雨)때에는 특(特)히 강우강도(降雨强度)에 따라서 각(各) 처리별(處理別)로 그 차이(差異)가 크게 나타났다. 2. 표면유출(表面流出)에 작용(作用)하는 주요인(主要因)의 상호작용(相互作用)과 영향도(影響度) 표면유출율(表面流出率)에 작용(作用)하는 주(主) 요인(要因), 즉(即) 토성(土性), 경사(傾斜), 강우(降雨), 피복(被覆), 식생요인(植生要因)에 관련(關聯)한 전(全) 실험(實驗)을 통(通)하여 각(各) 처리(處理)에서 발생(發生)된 표면유출율(表面流出率)의 평균치(平均値)의 차간(差間)에는 토성간(土性間), 경사도간(傾斜度間), 강우강도간(降雨强度間), 피복방법간(被覆方法間), 그리고 식생밀도간(植生密度間)에 각각(各各) 5%의 수준(水準)에서 유의성(有意性)이 인정(認定)되었다. 각(各) 요인간(要因間)의 상호작용(相互作用)은 토성(土性)과 경사(傾斜), 경사(傾斜)와 식생(植生), 토성(土性)과 경사(傾斜)와 강우(降雨), 토성(土性)과 경사(傾斜)와 피복요인(被覆要因)의 상호작용(相互作用)을 제외(除外)한 다른 요인간(要因間)의 상호작용(相互作用)은 각각(各各) 1%의 수준(水準)에서 표면유출율(表面流出率)에 영향(影響)을 미치었다. 인공강우(人工降雨)때에 나지사면(裸地斜面)에서 토성(土性), 경사(傾斜) 및 강우(降雨)의 3요인(要因)이 표면유출율(表面流出率)에 작용(作用)하는 영향도(影響度)는 강우강도(降雨江度)의 영향(影響)이 가장 크고 다음이 토성(土性), 경사(傾斜)의 순(順)이었다. 그리고 피복사면(被覆斜面)에서 토성(土性), 강우(降雨) 및 피복요인(被覆要因)의 영향도(影響度)에서는 피복(被覆), 강우(降雨), 토성(土性)의 순(順)이었으며, 토성(土性), 경사(傾斜), 피복요인(被覆要因)에서는 피복(被覆), 토성(土性), 경사(傾斜)의 순(順)이었다. 식생사면(植生斜面)에서 토성(土性), 경사(傾斜) 및 식생요인(植生要因)의 영향도(影響度)에서는 식생(植生), 토성(土性), 경사(傾斜)의 순(順)으로 작용(作用)하였다. 자연강우(自然降雨)때에 야외실험(野外實驗)에서는 사면피복(斜面被覆)의 영향(影響)이 가장 크고 다음이 토성(土性), 경사요인(傾斜要因)의 순(順)이었다. 3. 실험요인(實驗要因)과 토양유실량(土壤流失量) 토양유실량(土壤流失量)은 토성(土性), 강우강도(降雨强度), 사면경사도(斜面傾斜度), 피복처리(被覆處理)에 따라서 그 차이(差異)가 많았다. 자연강우하(自然降雨下)의 야외실험사면(野外實驗斜面)에서는 조토(粗土)에서 보다도 세토(細土)에서 약(約) 1.1~1.3배(倍)가 더 많았으며, 인공강우하(人工降雨下)의 실내실험(室內實驗)에서는 조토(粗土)에서 보다도 세토(細土)에서 약(約) 1.2~3.3배(倍)가 많았다. 인공강우하(人工降雨下)에서 사면경사도(斜面傾斜度)(log S)와 토양유실량(土壤流失量)(log E)간(間)에는 대체(大體)로 $E=aS^b$ (a, b는 상수(常數))의 관계(關係)가 있으며, b값은 강우강도(降雨强度)가 커짐에 따라서 작어지는 경향(傾向)을 보였다. 그리고 강우강도(降雨强度) (log I)와 토양유실량(土壤流失量) (E)간(間)에서는 대체(大體)로 $E=aI^b$의 관계(關係)가 있으며 b값은 경사도(傾斜度)가 커짐에 따라서 작어지는 경향(傾向)을 보였다. 자연강우하(自然降雨下)에서 토양유실량(土壤流失量)은 나지사면(裸地斜面)에서의 토양유실량(土壤流失量)에 비(比)하여 거적덮기에서 약(約) 38~41%, 토양침식방지액제피복(土壤侵蝕防止液濟被覆)에서 약(約) 20~22%, 그리고 새풀덮기에서 약(約) 14~15% 정도(程度)이었다. 식생사면(植生斜面)에서는 나지사면(裸地斜面)에 비(比)하여 식생밀도(植生密度) 소(疎) 때에 약(約) 7.1~16.4배(倍), 중(中) 때에 약(約) 10.0~17.9배(倍), 밀(密) 때에 약(約) 11.1~28.1배(倍)의 침식방지효과(浸蝕防止効果)가 있었다. 4. 토양침식(土壤侵蝕)에 작용(作用)하는 주요인(主要因)의 상호작용(相互作用)과 영향도(影響度) 토양침식(土壤侵蝕)에 작용(作用)하는 주(主) 요인(要因), 즉(即) 토성(土性), 경사(傾斜), 강우(降雨), 피복(被覆), 식생요인(植生要因)에 관련(關聯)한 전(全) 실험(實驗)을 통(通)하여 각(各) 처리(處理)에서 발생(發生)된 토양유실량(土壤流失量)의 평균치(平均値)의 차간(差間)에는 토성간(土性間), 경사도간(傾斜度間), 강우강도간(降雨强度間), 피복방법간(被覆方法間), 그리고 식생밀도간(植生密度間)에 각각(各各) 고도(高度)의 유의성(有意性)이 인정(認定)되었으며, 각요인간(各要因間)의 상호작용(相互作用)이 있어서도 대체(大體)로 큰 영향(影響)을 미치었다. 인공강우(人工降雨)때에 나지사면(裸地斜面)에서 토성(土性), 경사(傾斜) 및 강우(降雨)의 3개요인(個要因)이 토양침식(土壤浸蝕)에 작용(作用)하는 영향도(影響度)는 강우강도(降雨强度)의 영향(影響)이 가장 크고 다음이 토성(土性), 경사(傾斜)의 순(順)이었다. 그리고 피복사면(被覆斜面)에서 토성(土性), 강우(降雨) 및 피복요인(被覆要因)의 영향도(影響度)에서는 피복(被覆), 강우(降雨), 토성(土性)의 순(順)이었으며, 또 토성(土性), 경사(傾斜), 피복요인(被覆要因)의 영향도(影響度)에서는 피복(被覆), 토성(土性), 경사(傾斜)의 순(順)이었다. 식생사면(植生斜面)에서 토성(土性), 경사(傾斜) 및 식생요인(植生要因)의 영향도(影響度)는 경사(傾斜), 식생(植生), 토성(土性)의 순(順)으로 작용(作用)하였다. 자연강우(自然降雨)때에 야외실험(野外實驗)에서는 사면피복(斜面被覆)의 영향(影響)이 가장 크고 다음이 경사(傾斜), 토성(土性)의 순(順)이었다.

• 한국환경복원기술학회지
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• 제1권1호
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• pp.141-150
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• 1998

This study was conducted to find out the possibility of seeding of Zoysia japonica and woody plants for the revegetation of rock-exposed-cutslopes by Natural Topsoil Restoration Methods (NTRM). The 5cm thick layer of artificial soil was attached at rock-exposed cutslopes for the growth of Zoysia japonica and native woody plants by NTRM. The main results were summarized as follows. 1. Artificial soil attached at rock-exposed-slopes by NTRM was not eroded until recovered by Zoysia japonica and native woody plants. It shows extremely low soil erodibility. 2. One year later after seeding, woody plants show 100% ground coverage. But, in early stage, they grew more quickly at northwest slopes than at southeast slopes. 3. In seeding of Zoysia japonica, it grew more quickly at southeast slopes than at northwest slopes. Also, it grew better at lower part of the slopes than at middle part of the slopes. 4. After one year from seeding, the height of Lespedeza cyrtobotrya and Indigo/era pseudo-tinctoria were longer than any other plants. The next were Albizzia julibrissin, Lespedeza cuneata and wild flowers. The tree height of Rhus chinensis shows 28cm length, so it has enough possibility to be used for roadside revegetation works. 5. Lespedeza cyrtobotrya and Indigo/era pseudo-tinctoria show different importance values according to slope aspect. But, they show tendency to outweigh the other plants at all slope-aspects. 6. Most of the plants seeded by NTRM were germinated well and they covered rock-exposed-slopes so quickly and effectively. Thus it leads to conclusion that the revegetation methods used in this experiment was a very effective methods to recover rock-exposed-slopes by seeding of zoysia japonica and native woody plants.