• Title/Summary/Keyword: Composite ground effect

Search Result 117, Processing Time 0.022 seconds

A Study on Composite Ground Effects of Sand Piles (샌드파일 설치지반에서의 복합지반효과)

  • 천병식;여유현
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2001.03a
    • /
    • pp.397-404
    • /
    • 2001
  • Sand pile is one of the widely used ground improvement methods. Sand pile improved ground will have composite ground effects, even though the primary purpose is the accelerated consolidation. However, the consolidation of sand pile improved ground as a composite ground is substantially under developed. This study investigate the effect of composite ground for relatively low volume displacement sand piles. Plate bearing tests and earth pressure cell measurements are performed. It turned out that the contribution of sand pile as a load bearing mechanism is not substantial. However the bearing capacity of the surrounding clayey soil is increased by sixty percent, and it cause the stiffness change during consolidation. Therefore it is expected that, the effect of increased stiffness of sand pile improved ground is influenced by change of ground stiffness.

  • PDF

Smear Effect on Consolidation Behaviors of SCP-improved Ground (SCP 개량지만의 압밀거동에 대한 스미어 효과)

  • Kim, Yun-Tae
    • Journal of the Korean Geotechnical Society
    • /
    • v.20 no.2
    • /
    • pp.59-66
    • /
    • 2004
  • Sand compaction pile (SCP)-improved ground is composite soil which consists of the SCP and the surrounding soft soil. When a surcharge load is applied to composite ground, time-dependent behaviors occur in the composite soil due to consolidation according to radial flow toward the SCP. In addition, stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground that was conducted to investigate smear effect on consolidation behaviors of SCP-improved ground. The results showed that the smeared zone of soft clay had a significant effect on effective stress-pore water pressure response, stress transfer mechanism and stress concentration ratio of composite ground. Amount of stress transfer between the clay and the SCP was maximum in depth of z/H=0.25, and decreased with depth. Stress concentration ratio of composite ground was not constant, but depended on consolidation process. It was also found that the value of stress concentration ratio in soft clay with smeared zone was larger than that in soft clay without smeared zone.

Analysis of Stress Transfer Mechanism of SCP-Reinforced Composite Ground (SCP 복합지반의 응력전이거동 해석)

  • Kim, Yun-Tae;Park, Hyun-Il;Lee, Hyung-Joo;Kim, Sang-Kyu
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2004.03b
    • /
    • pp.227-234
    • /
    • 2004
  • Sand compaction pile (SCP) method is composed of compacted sand pile inserted into the soft clay deposit by displacement method. SCP-reinforced ground is composite soil which consists of the SCP and the surrounding soft soil. When a surcharge load is applied on composite ground, time-dependent behavior occurs in the soft soil due to consolidation according to radial flow toward SCP and stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground that was conducted to investigate consolidation characteristics and the stress transfer mechanism of SCP-reinforced composite ground. The results show that the consolidation of soft clay has a significant effect on the stress transfer mechanism and stress concentration ratio of composite ground

  • PDF

Composite Ground Effects on Small Area Replacement Ratio of Sand Piles (면적치환비가 작은 샌드파일 설치지반에서의 복합지반효과)

  • Chun, Byung Sik;Yeoh, Yoo Hyeon
    • Journal of the Korean GEO-environmental Society
    • /
    • v.2 no.3
    • /
    • pp.57-69
    • /
    • 2001
  • Sand pile is widely used as a ground improvement method. Although the primary purpose of constructing sand pile is accelerating consolidation, composite ground effect also can be gained by constructing sand pile. This study was accomplished to understand composite ground effect on the ground improved by sand piles which were applied as vertical drainage material when area replacement ratio was small relatively. For determining bearing capacities of origin ground and sand piles and analysing interaction between embankment and origin ground, bearing tests and earth pressure monitoring are performed. From the results, it turned out that the contribution of sand pile as a load bearing mechanism is not substantial. However, the bearing capacity of sand pile was increased to sixty percentages when compared with origin ground. The increasement of bearing capacity could be caused the change of consolidation characteristics during the process of consolidation by overburden load. Therefore, the composite ground effects depending on stiffness increasement of sand pile would be estimated as a factor decreasing consolidation settlement.

  • PDF

Evaluation of Composite Ground Improvement at Structural Foundation Ground by Super Injection Grouing (SIG공법에 의한 구조물기초지반에서의 복합지반개량 평가)

  • 김종국;손형호;이호관;성기광
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2002.03a
    • /
    • pp.347-354
    • /
    • 2002
  • In this paper, when structures are constructed in the soft ground with poor bearing capacity at Incheon International Airport(railroad area), as for the grouting columns built In soft ground by high pressure jet grouting with Triple tube rod(super injection grouting), the effects on reinforcement and bearing capacity of ground are investigated. A unconfined compressive strength tests has been performed on the specimens sampled from the grouting columns and a mass plate bearing test has been performed on a grouting column. The test results show that super injection grouting has a sufficient effect on composite ground improved of foundation ground and reatraint of settlement of structure.

  • PDF

A Study on Conceptual Structural Design of Wing for a Small Scale WIG Craft Using Carbon/Epoxy and Foam Sandwich Composite Structure

  • Kong, Chang-Duk;Park, Hyun-Bum;Kang, Kuk-Gin
    • Advanced Composite Materials
    • /
    • v.17 no.4
    • /
    • pp.343-358
    • /
    • 2008
  • This present study provides the structural design and analysis of main wing, horizontal tail and control surface of a small scale WIG (Wing-in-Ground Effect) craft which has been developed as a future high speed maritime transportation system of Korea. Weight saving as well as structural stability could be achieved by using the skin.spar.foam sandwich and carbon/epoxy composite material. Through sequential design modifications and numerical structural analysis using commercial FEM code PATRAN/NASTRAN, the final design structural features to meet the final design goal such as the system target weight, structural safety and stability were obtained. In addition, joint structures such as insert bolts for joining the wing with the fuselage and lugs for joining the control surface to the wing were designed by considering easy assembling as well as more than 20 years service life.

Evaluation of the Low Replacement Reinforced Ground Using Laboratory Tests (실내시험을 이용한 저치환 보강지반의 평가)

  • Bae, Woo-Seok
    • Journal of the Korean Society of Safety
    • /
    • v.23 no.6
    • /
    • pp.131-137
    • /
    • 2008
  • SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

The Study on The Numerical Analysis Method for Ground Improved by Cement Mixing Method (시멘트혼합처리공법이 적용된 지반의 수치해석 방법에 관한 연구)

  • Kim, Byung-Il;Hong, Kang-Han;Kim, Young-Seon;Han, Sang-Jae
    • Journal of the Korean Geosynthetics Society
    • /
    • v.17 no.4
    • /
    • pp.41-52
    • /
    • 2018
  • Since the composite ground design method is easy to apply for calculation or numerical analysis, it is applied to the design of cement mixing methods. However, the comparison studies between analysis and actual results such as a trial test and construction for the cement mixing method are few because the composite ground design method was developed for the compaction pile (SCP, GCP) methods. In this study, the results of various analysis methods, such as the composite ground analysis method (1 case) and the individual pile method (3 cases), were compared with actual measurements through a two-dimensional finite element numerical analysis. In case of the surface settlements, the results of study show that the individual plate method was larger than the actual measurements, while other methods are similar. The settlements at the under ground of the improved area is overestimated in all analysis methods. When comparing numerical analysis results for the horizontal displacement, and ground reaction forces, the individual pile method in equivalent wall concept was found to be the most similar to the measurements. The composite ground method was not able to predict the behavior of stress transfer (Arching effect) and it turned out that the prediction of horizontal displacement was too large.

Inter-lamina Shear Strength of MWNT-reinforced Thin-Ply CFRP under LEO Space Environment

  • Moon, Jin Bum;Kim, Chun-Gon
    • Composites Research
    • /
    • v.30 no.1
    • /
    • pp.7-14
    • /
    • 2017
  • In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum ($2.5{\times}10^{-6}torr$), atomic oxygen (AO, $9.15{\times}10^{14}atoms/cm^2{\cdot}s$), ultraviolet light (UV, 200 nm wave length) and thermal cycling ($-70{\sim}100^{\circ}C$) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature ($27^{\circ}C$), high temperature ($100^{\circ}C$) and low temperature ($-100^{\circ}C$) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thin-ply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.

Study on settlement characteristics of stone column reinforced in Sabkha through in-site loading test and numerical analysis (현장시험과 수치해석을 통한 암염층(Sabkha)에 보강된 스톤컬럼의 침하거동에 관한 연구)

  • Kim, Se-Won;Yang, Jeong-Hun;Kim, Ki-Ho;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2009.09a
    • /
    • pp.1214-1223
    • /
    • 2009
  • In this study, a composite behavior of stone columns reinforced in soft ground, Sabkha, have been evaluated by a series of field measurements and numerical analysis. Field loading tests were performed to verify the effect of the composite ground reinforced by stone columns in Kayan, Saudi. The settlement measured in the field test was compared with the settlement calculated by the Priebe method and the numerical analysis using ABAQUS. It is found that the settlement estimated using the Priebe method significantly overestimated the settlement measured in the field test. In addition, it is confirmed that consideration of confinement effect exerted by surrounding stone columns in a numerical simulation is indispensable to estimate the settlement of composite ground.

  • PDF