• Coupled systems mechanics
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• 제11권5호
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.963-970
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• 2010

In this study, a series of thermal numerical analysis was conducted through the ground condition and the length and shape of the energy pile. In order to investigate the effect of the thermal properties of ground condition, grout and pile type on heat transfer efficiency in the U-type heat exchanger in energy pile, thermal numerical analysis was done by using ABAQUS. ABAQUS, a finite element analyzing program, was employed to evaluate the temperature distribution on the cross section of energy pile system incorporating HDPE - grout - pile - Ground condition which consists of clay, sand, rock type soil and ground water.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 가을학술발표회 논문집
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• pp.137-144
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• 1992

This paper reports a case study of dynamic consolidation. The objective of the study is to evaluate the effectiveness of ground improvement at the site for Hyundai Petrochemical Compound constructed at Daesan-Myeon, Seosan-Gun in the western shores of Korea. The site ground was prepared by filling on the existing soft marine deposit which consists of a loose granular soil layer and a medium stiff clay layer. For the stabilization of site ground, the compaction was executed in three different procedures with same pounder weigh, drop height and imprint spacing. The post investigation showed that the object was successfully achieved indicating a significant increase of bearing capacity of the treated ground. In this study the effectiveness of dynamic consolidation is evluated for various factors the applied energy, temping sequences, the radial distance from the imprint location and the depth of bed rock.

• 대한토목학회논문집
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• 제34권2호
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• pp.529-536
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• 2014

점토-시멘트 혼합토의 물리적 특성인 함수비, 비중, 단위중량과 간극비 등은 혼합토의 강도, 압축성, 압밀거동 예측 등에 적용되는 주요한 인자이다. 기존에는 혼합토의 물리적 특성을 복잡한 실내시험 및 시공 후 확인조사를 통해 이루어 졌다. 본 연구는 점토 함수비 90~170%, 시멘트 함유율 5~25%와 재령기간은 3~90일 조건으로 실내시험을 수행하였으며, 양생 후 혼합토 함수비, 비중, 단위중량과 간극비 등에 대한 변화를 분석하였다. 시험결과를 이용하여 원지반 점토 함수비, 시멘트 함유율과 재령기간 등의 역학적 관계를 바탕으로 혼합토의 함수비, 비중과 단위중량에 관한 물성 예측식을 제안하였다. 혼합토의 물성 예측식을 지반공학 분야에서 일반적으로 사용하는 간극비 산출식에 대입하여 혼합토의 간극비 예측식을 도출하였으며, 방콕 점토를 대상으로 간극비에 대한 실험결과와 본 연구에서 제안한 예측식을 검증하였다.

• Elastomers and Composites
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• 제24권4호
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• pp.276-289
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• 1989

This study deals with both effects of inorganic fillers to vulcanized rubbers such as NR, CR, EPDM, NBR & SBR and inorganic characteristics of domestic fillers in comparision with hard clay produced in the USA. The results were as follows. 1. Main ingredient of domestic clay "Ha-dong clay" was Halloysite, "No-ha Island" was Pyrophyllite with $\alpha$-Quartz, and both of "Hard clay" & "Hwa-soon clay" were proved to be Kaolinite by XRD, DT-TGA and chemical analysis by XRF. 2. Tensile strength value of SBR compounded with these fillers, was Hard clay $146kg\;f/cm^2$, Kaolinite $123kg\;f/cm^2$, Pyrophyllite $82kg\;f/cm^2$, Halloysite $80kg\;f/cm^2$, precipitated $CaCO_3\;27kg\;f/cm^2$, and ground $CaCO_3$ was $21kg\;f/cm^2$. These results showed the increase of seven times according to filler species. 3. The physical properties of non-crystalline rubbers, such as SBR, NBR & EPDM, compared with NR & CR, have been considerably changed according to crystalline phase, particle size, shape and surface structure of fillers. Especially, tensile strength value in case of SBR & EPDM, was differentiated about 1.5 times by the particle size of fillers. 4. In SBR, physical properties of rubber compounded with Kaolinite which was surface treated with fatty acid and silane, almost approach to the value of hard clay. 5. Delayed cure time of Kaolinite and decrease of rubber properties by $CaCO_3$ can be improved by blending kaolinite & $CaCO_3$ in the ratio of 2:1.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.583-590
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• 2000

The installation of vertical drains by using a mandrel causes significant disturbance of the subsoil. Thus a smear zone may be developed with reduced permeability and increased compressibility. In this paper the extent of smear zone developing ground disturbance with the installation of mandrels are analysed by field smear zone test. The extent and the consolidation characteristics of smear zones around the mandrels is compared with the shape, the size of mandrel and penetration speed and is evaluated from the field smear test results. (circular, sqare, rectangle and oval type)

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.329-332
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• 2002

In the present study, in order to apply a cyclic viscoelastic-viscoplastic constitutive model to multi-layered ground conditions during large earthquake, the numerical simulations of the 1995 Hyogoken Nanbu Earthquake at Port Island, Kobe, Japan, were performed by the seismic respons analysis. From the seismic response analysis, it was verified that a cyclic viscoelastic-viscoplastic constitutive model can give a good description of the damping characteristics of clay accurately during large event which induces plastic deformation in large strain range.

• Geomechanics and Engineering
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• 제8권5호
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• pp.707-726
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• 2015

This paper investigates the time dependent behaviour of Haarajoki test embankment on soft structured clay deposit. Half of the embankment is constructed on an area improved with prefabricated vertical drains, while the other half is constructed on the natural deposit without any ground improvement. To analyse the PVD-improved subsoil, axisymmetric vertical drains were converted into equivalent plane strain conditions using three different approaches. The construction and consolidation of the embankment are analysed with the finite element method using a recently developed anisotropic model for time-dependent behaviour of soft clays. The constitutive model, namely ACM-S accounts for combined effects of plastic anisotropy, interparticle bonding and degradation of bonds and creep. For comparison, the problem is also analysed with isotropic Soft Soil Creep and Modified Cam Clay models. The results of the numerical analyses are compared with the field measurements. The results show that neglecting effects of anisotropy, destructuration and creep may lead to inaccurate predictions of soft clay response. Additionally, the numerical results show that the matching methods accurately predict the consolidation behaviour of the embankment on PVD improved soft clays and provide a useful tool for engineering practice.

• 한국지반공학회논문집
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• 제19권4호
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• pp.75-81
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• 2003

초연약 고소성의 준설해성점토를 보강하기 위하여 Micro-Fiber(MF)재를 혼합하여 다양한 실내시험을 수행하였다. 준설점토의 함수비를 3종으로 조정하고 각각의 시료에 MF를 길이와 혼합율을 변화시키면서 일축압축 및 삼축압축 시험을 통하여 보강특성을 검토하였다. 또한, 양생일수벽로 강도증가 경향을 평가하였으며, 폐석회(Waste Lime, WL)의 추가혼합이 보강기능을 증대시키는지 여부를 검토하였다. 실험결과, MF를 혼합함에 따라 준설점토의 강도가 자연함수비에 무관하게 약 50% 증가하였으며, MF의 길이가 길수록 보강효과가 크게 나타났다. 또한, 합리적인 MF의 혼합율은 2% 정도이며, 추가적으로 폐석회를 약 10% 혼합할 경우 중장비주행이 가능한 보강효과가 나타나는 것을 확인하였다.

• 한국지반공학회지:지반
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• 제14권5호
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• pp.77-88
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• 1998

본 논문은 동해안의 지형발달 및 해수면 변화와 관련하여 포항지역이 옹기되고 있는 증거를 제시하고, 해성점토의 분포와 공학적 특성을 규명한 것이다. 지금부터 약 10,000년 전 동해안의 해수면은 현해수면보다 약 25.0m 아래에 존재한 것으로 추정되며, 지각변동으로 인하여 포항시의 해수면 아래에서 퇴적된 해성점토층은 주로 해수면 위에서 발견된다. 포항시 두호1동 및 장성동의 해성점토는 GL-7.8m 이하에서 과압밀비가 0.77이하이며 5./P:비가 0.14이하인 것으로 판단해 볼 때, 미압밀상태인 것으로 추정된다. 그러나 미압밀상태를 확인하기 위해서는 보다 정확한 측정과 해석이 필요하다.