• 제목/요약/키워드: geogrids

검색결과 79건 처리시간 0.026초

지오그리드의 한계 크리프 변형률 해석을 위한 제안 (Suggestion for Interpretation of Limit Creep Strain of Geogrids)

  • 전한용;목문성
    • 한국지반신소재학회논문집
    • /
    • 제6권4호
    • /
    • pp.1-6
    • /
    • 2007
  • 크리프 시험결과 해석을 통하여 한계 크리프 변형률 개념에 의한 크리프 감소인자를 평가하는 새로운 절차를 소개하였다. 지오그리드의 한계 크리프 변형률을 결정하기 위하여, Sherby-Dorm Plots을 적용하였으며 그 결과를 각각 비교, 해석하였다. 이로부터 본 연구에 사용된 지오그리드 시료들의 크리프 감소인자는 1.45임을 알 수 있었다. 10% 임계 크리프 변형률에서의 크리프 감소인자 비교를 통하여 본 연구에 사용된 지오그리드 시료들의 크리프 감소인자의 감소폭은 약 0.06~0.14 범위임을 확인할 수 있었다.

  • PDF

New horizon of earth reinforcement technique - current and future -

  • Otani, Jun
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 2007년 가을학술발표회
    • /
    • pp.514-527
    • /
    • 2007
  • Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

  • PDF

지오그리드의 시공시 손상 및 크리프 복합효과에 대한 실험적 연구 (An Experimental Study on the Combined Effect of Installation Damage and Creep of Geogrids)

  • 조삼덕;이광우;오세용;이도희
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 2005년도 춘계 학술발표회 논문집
    • /
    • pp.561-568
    • /
    • 2005
  • The factors affecting the long-term design strength of geogrid can be classified into factors on creep deformation, installation damage, temperature, chemical degradation and biological degradation. Especially, creep deformation and installation damage are considered as main factors to determine the long-term design strength of geogrid. Current practice in the design of reinforced soil is to calculate the long-term design strength of a reinforcement damaged during installation by multiplying the two partial safety factors, $RF_{ID} and RF_{CR}$. This method assumes that there is no synergy effect between installation damage and creep deformation of geogrids. Therefore, this paper describes the results of a series of experimental study, which are carried out to assess the combined effect of installation damage and creep deformation for the long-term design strength of geogrid reinforcement. The results of this study show that the tensile strength reduction factors, RF, considering combined effect between installation damage and creep deformation is less than that calculated by the current design method.

  • PDF

보강용 복합 지오텍스타일의 장기성능 평가 (Evaluation of Long-Term Performance of Composite Geotextiles for Reinforcement)

  • 정한용;류중재;이수남;안양님;조봉균
    • 한국지반신소재학회논문집
    • /
    • 제2권2호
    • /
    • pp.33-38
    • /
    • 2003
  • 부직포와 결합한 보강용폴리에스터 직포 지오텍스타일을 제조한 다음 크리프 시험결과로 부터 허용인장강도를 구하였다. 설계 및 시공을 고려한 안전율로 부터 장기설계인장강도를 구하였고 보강기능을 조사하기 위하여 지오그리드와 복합 직포 지오텍스타일의 장기거동을 비교하였다. 실험결과로 부터 보강용 직포 지오텍스타일이 지오그리드와 같은 충분한 보강성능이 있음을 확인할 수 있었고, 향후 추가실험을 통하여 복합 직포 지오텍스타일의 우수한 보강성능이 지속적으로 검증되어야 할 것으로 생각된다.

  • PDF

Rainfall induced instability of mechanically stabilized earth embankments

  • Roy, Debasis;Chiranjeevi, K.;Singh, Raghvendra;Baidya, Dilip K.
    • Geomechanics and Engineering
    • /
    • 제1권3호
    • /
    • pp.193-204
    • /
    • 2009
  • A 10.4-m high highway embankment retained behind mechanically stabilized earth (MSE) walls is under construction in the northeastern part of the Indian state of Bihar. The structure is constructed with compacted, micaceous, grey, silty sand, reinforced with polyester (PET) geogrids, and faced with reinforced cement concrete fascia panels. The connections between the fascia panels and the geogrids failed on several occasions during the monsoon seasons of 2007 and 2008 following episodes of heavy rainfall, when the embankment was still under construction. However, during these incidents the MSE embankment itself remained by and large stable and the collateral damages were minimal. The observational data during these incidents presented an opportunity to develop and calibrate a simple procedure for estimating rainfall induced pore water pressure development within MSE embankments constructed with backfill materials that do not allow unimpeded seepage. A simple analytical finite element model was developed for the purpose. The modeling results were found to agree with the observational and meteorological records from the site. These results also indicated that the threshold rainwater infiltration flux needed for the development of pore water pressure within an MSE embankment is a monotonically increasing function of the hydraulic conductivity of backfill. Specifically for the MSE embankment upon which this study is based, the analytical results indicated that the instabilities could have been avoided by having in place a chimney drain immediately behind the fascia panels.

Seismic fragility assessment of shored mechanically stabilized earth walls

  • Sheida Ilbagitaher;Hamid Alielahi
    • Geomechanics and Engineering
    • /
    • 제36권3호
    • /
    • pp.277-293
    • /
    • 2024
  • Shored Mechanically Stabilized Earth (SMSE) walls are types of soil retaining structures that increase soil stability under static and dynamic loads. The damage caused by an earthquake can be determined by evaluating the probabilistic seismic response of SMSE walls. This study aimed to assess the seismic performance of SMSE walls and provide fragility curves for evaluating failure levels. The generated fragility curves can help to improve the seismic performance of these walls through assessing and controlling variables like backfill surface settlement, lateral deformation of facing, and permanent relocation of the wall. A parametric study was performed based on a non-linear elastoplastic constitutive model known as the hardening soil model with small-strain stiffness, HSsmall. The analyses were conducted using PLAXIS 2D, a Finite Element Method (FEM) program, under plane-strain conditions to study the effect of the number of geogrid layers and the axial stiffness of geogrids on the performance of SMSE walls. In this study, three areas of damage (minor, moderate, and severe) were observed and, in all cases, the wall has not completely entered the stage of destruction. For the base model (Model A), at the highest ground acceleration coefficient (1 g), in the moderate damage state, the fragility probability was 76%. These values were 62%, and 54%, respectively, by increasing the number of geogrids (Model B) and increasing the geogrid stiffness (Model C). Meanwhile, the fragility values were 99%, 98%, and 97%, respectively in the case of minor damage. Notably, the probability of complete destruction was zero percent in all models.

지오그리드 매트리스기초에 관한 실험적 연구 (Experimental Study on Geogrid-Mattress Fundation)

  • 주재우
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 1994년도 가을 학술발표회 논문집
    • /
    • pp.182-190
    • /
    • 1994
  • Mattress foundations using geogrids are often used on soil foundations to increase the supporting capability of a mattress-soil foundation system, in which the mattress foundation trasmits a point load applied above to a wider area of the soil foundation underneath. To examine this load dispersion capability of the mattress foundation, model experiments were carried out on lab-floor. Expecially, the effect of the thickness of the mattress and the subgrade modulus of the soil foundation on load dispersion are considered. The load distribution and the tensile force generated on geogrid of the upper part of the mattress are examined in the paper.

  • PDF

전단시험에 의한 토목섬유 보강재의 지반 적용성 평가 (An Experimental Evaluation for Geotechnical Properties of Geosynthetic composites by Direct Shear Test)

  • 조성호;최세환;차동환;류중재;전한용
    • 한국섬유공학회:학술대회논문집
    • /
    • 한국섬유공학회 2003년도 봄 학술발표회 논문집
    • /
    • pp.267-270
    • /
    • 2003
  • 일반적으로 토목 공사에서 구조의 보강 용도로 주로 사용되는 지오그리드(geogrids)는 우수한 인장 탄성계수와 인장강력을 지니고 있어서 하중이 집중적으로 작용하는 토목 구조물에서 보강기능을 원활히 수행하는 보강재료 이지만, 비교적 큰 격자상 외관 구조를 가지므로 지오그리드를 관통하는 각종 물질, 특히 함유 수분과 세립질 토양의 이동이나 유실 등을 효과적으로 제어하지 못한다는 단점도 있어 사용상의 제약이 있다. (중략)

  • PDF

Analysis of Reduction Factors to Creep Deformation of Reinforced Geosynthetics

  • Jeon, Han-Yong;Yuu, Jung-Jo;Mok, Mun-Sung
    • 한국섬유공학회:학술대회논문집
    • /
    • 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
    • /
    • pp.104-104
    • /
    • 2003
  • Geosynthetic Reinforcements - membrane drawn type, warp/knitted type, junction bonded type and composite type geogrids, strip type reinforcement - were used to compare the long-term perfor-mance by total factor of safety with reduction factors during service periods. To evaluate the reduction factors, wide-width tensile property, installation damage, creep deformation, chemical and biological degradation tests were performed. Long-term design strengths of geosynthetic reinforcements were calculated by using GRI standard Test Method GG4.

  • PDF