시멘트계 결합재가 적용된 지오텍스타일의 접촉면 전단강도 평가

손동건 ( Son Dong-geon ),변용훈 ( Byun Yong-hoon ) 한국농공학회 2022 한국농공학회논문집 Vol.64 No.1

Multi-layered geotextile tubes may have problems on its stability when used as cofferdam. This study presents the shear strength characteristics at the interface between geotextiles and a cementitious binder material to improve the stability of the multi-layered geotextile tubes. In this study, two different types of geotextiles are used. After mixing with a rapid setting cement, fly ash, sand, accelerator, and water, the cementitious binder material is prepared at the interface between two geotextile samples and cured under water for a desired period. The specimen is placed on upper and lower direct shear boxes by using clamping systems. A series of direct shear tests for two different geotextiles are performed along the curing time under three vertical stresses. Experimental results show that the shear strength at the interface between the cementitious binder material and geotextiles is greater than that at the interface between two geotextiles. For two types of geotextiles, apparent cohesion occurs at the interface between the cementitious binder material and geotextiles. In addition, the friction angles for any curing time are improved, compared to the interface between two geotextiles. The cementitious binder material suggested for the interface between two geotextiles may be useful for the reinforcement of multi-layered geotextile tubes.

An Analytical Study on Bearing Mechanism of Very Soft Ground Covered with Geotextile by Effects of Friction between Ground and Geotextile

안동한(Ahn Dong-Han),유승경(You Seung-Kyong) 한국토목섬유학회 2010 한국지반신소재학회 논문집 Vol.9 No.4

일반적으로 초연약지반에서는 건설장비의 주행성 확보 등을 위하여 토목섬유와 같은 표층 보강재를 적용하게 된다. 그러나 최근 토목섬유로 표층 처리된 초연약지반의 거동에 관한 많은 고찰이 수행되어 왔지만 대부분의 연구에서 토목섬유와 지민의 경계조건을 적절히 표현하지 못하고 있는 실정이다. 따라서 본 연구에서는 토목섬유와 지반의 경계조건이 토목섬유로 표층 처리된 초연약지반의 거동에 미치는 영향에 대하여 수치해석적 고찰을 수행하였다. 수치해석에서는 토목섬유와 지반의 마찰에 대한 정제조건을 다양하게 표현하기 위하여 조인트 요소를 적용하였다. 수치해석의 결과는 기존의 실내모형실험 결과와의 비교를 통하여 그 신뢰성을 검증하였으며 파라메트릭 스터디를 통하여 토목섬유와 지반의 경계조건에 따른 초연약지반의 거동을 규명하였다. In general, ground surface strengthening such as using geotextile is needed to secure trafficability of construction equipment. There are many researches for mechanical beha-vior of very soft ground covered with geotextile, however, most of them are under the condition to fix geotextile completely. In this study, numerical analyses were carried out to figure out the effects of restricting conditions of geotextile on bearing mechanism of very soft ground covered with georexrile. In numerical analyses, joint elements were used to figure out the friction properties between ground and geotextile. The results of numerical analyses were compared with the results of model test. In conclusion, the effects of restricting conditions of geotextile on bearing mechanism of very soft ground covered with geotextile became clear.

A Study on Thermally Bonded Geotextile Separator and Properties of Waste Landfill Application of PVA Geotextile/HDPE Geomembrane Composites

Min, Kyung-Ho,Seo, Jung-Min,Hwang, Beong-Bok,Lee, In-Chul,Ruchiranga, Jayasekara Vishara,Jeon, Han-Yong,Jang, Dong-Hwan,Lim, Joong-Yeon The Korean Society for Composite Materials 2008 Advanced composite materials Vol.17 No.3

This paper is concerned with geotextiles bonded chemically with geogrid to form a geocomposite. Geotextiles, thermally bonded and non-woven, play an important role as a separator. Also, this study investigates the resistance to the application environment of geotextile composites. Here, numerous tests have been performed and it was revealed from experimental results that thermally bonded geotextile in geosynthetic composites showed superior characteristics to that manufactured from needle punched non-woven method in terms of tensile strength, tensile strain and high separation performance. It was noted from experiments that the geotextile prepared for separation purpose and manufactured in a thermal bonding method showed relatively low permittivity so that it could be used as a smooth separator. In addition, PVA geotextile/HDPE geomembrane composites were designed and manufactured to investigate the waste landfill related properties. Numerous experiments have been performed and experimental results were summarized to evaluate practical applicability of PVA geotextile/HDPE geomembrane composites. Among the properties of proposed geomembrane composites, evaluation has been focused on the investigation of mechanical properties, AOS (apparent opening size), permittivity and ultraviolet stability.

Bearing capacity of geotextile-reinforced sand with varying fine fraction

Deb, Kousik,Konai, Sanku Techno-Press 2014 Geomechanics & engineering Vol.6 No.1

Use of geotextile as reinforcement material to improve the weak soil is a popular method these days. Tensile strength of geotextile and the soil-geotextile interaction are the major factors which influence the improvement of the soil. Change in fine content within the sand can change the interface behavior between soil and geotextile. In the present paper, the bearing capacity of unreinforced and geotextile-reinforced sand with different percentages of fines has been studied. A series of model tests have been carried out and the load settlement curves are obtained. The ultimate load carrying capacity of unreinforced and reinforced sand with different percentages of fines is compared. The interface behavior of sand and geotextile with various percentages of fines is also studied. It is observed that sand having around 5% of fine is suitable or permissible for bearing capacity improvement due to the application of geosynthetic reinforcement. The effectiveness of the reinforcement in load carrying capacity improvement decreases due to the addition of excessive amount of fines.

Numerical Analysis on Behaviors of Very Soft Ground Improved by Geotextile

안동한(Ahn Dong-Han),유승경(You Seung-Kyong) 한국토목섬유학회 2009 한국지반신소재학회 논문집 Vol.8 No.3

최근 우리나라에서 활발히 진행되고 있는 준설매립 공사에서는 일반적으로 시공 장비의 주행성을 확보하기 위한 표층처리공법으로써 지오텍스타일을 부설하는 경우가 많다. 지오텍스타일이 부설된 초연약점토지반의 지지력의 계산은 기존에 몇 가지 제안되어 있지만 아직 명확히 확립되어있지 않기 때문에 시공실적에 기초한 경험적인 방법이 사용되고 있는 실정이다. 본 논문에서는 지오텍스타일이 부설된 초연약지반의 합리적인 지지력 산정방법 확립의 일환으로 일련의 수치해석을 실시하였다. 수치해석 결과 초연약지반의 표층을 지오텍스타일로 보강함으로써 초연약지반의 항복 후에도 개량된 지반의 지반응력은 증가함을 알 수 있었으며 지요텍스타일에서 발생되는 최대인장응력은 하중이 증가함에 따라 재하 끝단부에서 크게 발생됨을 알 수 있었다. In generally, ground surface strengthening such as using geotextile is needed to secure trafficability of construction equipment. Several calculation methods for bearing capacity for very soft ground improved by geotextile have been proposed already but they are not established yet. In this paper, elastoplastic finite element analysis is carried out to estimate bearing capacity improvement for very soft ground reinforced by geotextile. In conclusion, by reinforcing with geotextile the bearing capacity improvement of very soft ground is increased with the increase of the settlement after yielding. And it is enough that the length of geotextile is about 3~4 times of the loaded width for the effect to the bearing capacity improvement. Finally, the biggest tensile force of geotextile occurs at an edge of the uniform load.

원형토조 시험을 통한 반복하중에 따른 부직포의 침하특성

최찬용(Choi Chan-Yong),이진욱(Lee Jin-Wook),김현기(Kim Hyun-Ki) 한국토목섬유학회 2009 한국지반신소재학회 논문집 Vol.8 No.2

국내 대부분을 차지하고 있는 자갈 도상궤도는 지속적인 열차반복하중에 의해 마모, 노반으로 관입, 노반표면의 불균질 등에 의해 도상자갈의 기능을 상실하게 된다. 이러한 현상이 지속적으로 발생하면 설계 당초 주요 기능이었던 배수기능을 충분히 발휘하지 못하기 때문에 강우가 노반에 체류되고 물로 인해 간극수압이 증가하여 전단강도가 저하되어 점진적으로 노반이 연약화된다. 이 논문에서는 원형모형실험을 이용하여 부직포 3종류에 대하여 0일, 3일, 7일 체수조건으로 하여 반복하중을 재하시킴으로써 부직포의 침하특성과 지지력 변화를 관찰하였다. 실험결과 0일 체수조건에서 토목섬유 보강과 무보강에 따라 최종 변위는 약 1% 차이가 있으며, 지반의 포화도가 증가함에 따라 침하량이 커지는 경향이 있었다. 보강재의 중량이 클수 록 소성침하량이 작게 평가되었으며, 임계 함수비를 초과한 경우에는 부직포의 인장강도와 중량에 따라 침하량의 차이가 발생하였다. 또한 무보강과 비교해 볼 때 부직포에 의한 토압 저감효과는 있으나, 부직포의 중량에 의한 토압저감 효과는 영향이 미미한 것으로 평가되었다. The ballast track, the most common type of conventional railroad track in Korea, is deteriorated by abrasion of ballast, it's penetration into roadbed, and rugged surface of roadbed caused by cyclic loading of train. Persistent occurrence of those phenomena lead to insufficient drain capacity, one of major factors in track design, and it increases pore water pressure and decreases of shear strength under rainfall condition leading to unstable roadbed. In this study, cylindrical model tests are executed for 3 types of geotextile applying cyclic loading in order to observe the characteristics of displacement and bearing capacity of geotextile, and undrained condition has been applied for 0 day, 3 days and 7 days to each geotextiles. The results showed that there was about 1% difference at the final displacement rates between reinforced soils and nature soils and the displacement of the ground surface increases along with the degrees of the saturation. And in case that water contents exceeds the threshold, it is also apparent that weight and tensile strength of geotextile influences displacement of the ground surface. And the larger weight of geotextile is, the smaller plastic displacement. It is evaluated that non-woven fabric comes into effect on reducing the bearing capacity but, the weight of geotextile has little influence on it.

Performance Assessment of PVA Geotextile/HDPE Geomembrane Composites

전한용,홍상진,류원석,Jeon, Han-Yong,Hong, Sang-Jin,Lyoo, Won-Seok Korean Geosynthetics Society 2005 한국지반신소재학회 논문집 Vol.4 No.1

폐기물 매립지 관련 특성을 조사하기 위하여 PVA 지오텍스타일/HDPE 지오멤브레인 복합재료를 제조하였다. PVA 지오텍스타일의 인장특성, 인열 및 파열강도, 유효구멍크기와 투수성 등을 각각 측정하였다. 또한 침출수에 대한 화학저항성과 자외선 안정성도 측정하였으며, 하중조건에 따른 크리프 변형거동과 마찰특성도 측정하였다. 이들 결과로부터 PVA 지오텍스타일/HDPE 지오멤브레인 복합재료는 일반적으로 폐기물 매립지에 적용되는 폴리프로필렌이나 폴리에스테르 지오텍스타일에 비해 우수한 특성을 나타내었다. 끝으로, 감소인자 분석으로부터 PVA 지오텍스타일/HDPE 지오멤브레인 복합재료의 크리프 변형거동도 폴리프로필렌이나 폴리에스테르 지오텍스타일에 비해 안정함을 알 수 있었다. PVA geotextile/HDPE geomembrane composites were made to examine the waste landfill related properties. Tensile properties, tear and bursting strengths, AOS(apparent opening size) and permittivity of PVA geotextiles were evaluated, respectively. Ultraviolet stability and chemical resistance to the leachate was evaluated also. Friction property and creep deformation were tested at various loading condition. From this, it was seen that PVA geotextile/HDPE geomembrane composites have more excellent properties than the typically used polypropylene and polyester geotextiles in waste landfill. Finally, creep deformation behaviours of PVA geotextile/HDPE geomembrane composites were more stable than polypropylene and polyester geotextiles through the reduction factor analysis.

Model Test Study on the Behavior of Geotextile-Encased Sand Pile in Soft Clay Ground

유완규,김병일,조완제 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3

When constructing structures receiving high vertical and horizontal force such as port facilities, caissons and breakwaters on a softground on the sea or seashore, it is very important to increase the strength of the ground and inhibit excessive settlement. Recently,there have been numerous studies on the method of wrapping the outer wall of granular piles with geotextile or geogrid that has acertain level of tensile strength. Since the geotextile increases the strength of granular piles by confinement effects, those confinedgranular piles more advantages than the Conventional Sand Compaction Piles (SCP) in terms of the bearing capacity and settlement. Furthermore, this method consumes less aggregate compared to the conventional Sand Compaction Pile (SCP) or GravelCompaction Pile (GCP) method. This study proposed to determine the characteristics of mechanical behaviors such as bearingcapacity and stress concentration ratio of a composite ground improved using SCPs reinforced with geotextile (Geotextile-EncasedSand Pile, GESP) as an alternative to the conventional SCP method. With this purpose, several loading tests were conducted on theartificially sedimented clay grounds reinforced using conventional SCPs and GESPs with geotextiles of three different tensilestrengths with various replacement ratios. Based on the results of this study, the bearing capacity of the soft clay ground reinforced bythe GESPs is larger than that of the soft ground reinforced by the conventional SCPs and the failure mode of the GESPs is bucklingdifferent from the bulging of the SCPs. The tensile strength of the geotextile has little effect on the bearing capacity in the bucklingfailure of GESPs.

흙-직포간의 접촉면 전단강도 산정

윤주문(Youn Choo-Moon),안현호(An Hyun-Ho),서병욱(Seo Byoung-Wook),이석원(Lee Seok-Won) 한국토목섬유학회 2006 한국지반신소재학회 논문집 Vol.5 No.3

흙 자체의 전단강도와 흙과 직포사이의 접촉면 전단강도를 산정하기 위해서 본 연구에서는 대형직접전단시험기를 사용하였다. 두 종류의 흙(모래와 점토)과 한 종류의 직포를 실험에서 사용하였다. 본 연구에서는 총 9번의 시험을 수행하였다. 그 결과, 모래 자체는 30°의 내부마찰각을 나타내었다. 직포와 모래의 접촉면 마찰각은 26°로 87%의 효율을 나타내었다. 이와 비슷하게 직포와 점토의 접촉면 마찰각은 7.7°를 나타내었다. Large-scale direct shear tests were conducted in order to evaluate both the shear strength of soil itself and the interface shear strength between soil and woven geotextile. Two types of soil (sand and clay) with a woven geotextile were used in the experimental program. Total nine tests were conducted in this study. It has been found from the experimental results that the friction angle of sand itself were 30°. Interface friction angle between woven geotextile and sand showed 26° indicating an efficiency of 87%. Similarly, interface friction angle between woven geotextile and clay showed 7.7°.

쇄석-지오텍스타일간의 접촉면 전단강도 산정

이석원(Lee Seok-Won),윤주문(Youn Choo-Moon),안현호(An Hyun-Ho),서병욱(Seo Byoung-Wook) 한국토목섬유학회 2006 한국지반신소재학회 논문집 Vol.5 No.1

쇄석의 전단강도와 쇄석과 부직포사이의 접촉면 전단강도를 산정하기 위해서 본 연구에서는 대형직접전단시힘기를 사용하였다. 두 개의 서로 다른 쇄석의 단위중량을 한 종류의 직포와 두 종류의 부직포인 총 3가지 형태의 토목섬유에 고려하였다. 본 연구에서는 총 15번의 시험을 수행하였다. 그 결과는 쇄석의 단위중량이 각각 1.4 t/㎥과 1.5 t/㎥일 때 47˚와 57˚익 내부마찰각을 나타내었다. 부직포와 쇄석의 접촉면 마찰각은 쇄석의 내부마찰각에 비하여 A타입에서 39˚로 83%의 효율을 보였으며 B타입은 42˚로 89%의 효율을 나타내었다. 이와 비슷하게 직포와 쇄석의 접촉면 마찰각은 39˚로 83%의 효율을 나타내어 비교적 거칠기가 작은 A타입 부직포와 거의 동일한 결과를 보였다. Large-scale direct shear tests were conducted in order to evaluate both the shear strength of crushed stone itself and the interface shear strength between crushed stone and geotextile. Total three types of geotextile (i.e. one woven geotextile and two nonwoven geotexriles) were used in the experimental program, considering two different values for the unit weight of crushed stone. Total fifteen tests were conducted in this study. It has been found from the experimental results that the friction angles of crushed stone itself were 4r and 5r under the unit weights of crushed stone being 1.4 t/㎥ and 1.5 t/㎥, respectively. Interface friction angle between nonwoven geotextile and crushed stone showed 39˚ for type A indicating an efficiency of 83% and 42˚ for type B indicating an efficiency of 89%. Similarly, interface friction angle between woven geotextile and crushed stone showed 39˚ ndicating an efficiency of 83%.