• 한국지반공학회논문집
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• 제24권12호
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• pp.75-84
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• 2008

순환골재를 이용한 다공질 콘크리트 말뚝(RAPP, Recycle aggregate porous concrete pile) 공법은 연약지반에서 원지반과 다져진 다공질 콘크리트 말뚝이 복합지반을 이루어 연약지반을 개량하는 공법이다. 본 연구에서는 순환골재를 이용한 다공질 콘크리트 말뚝의 강도정수 및 응력-변형을 관계를 조사하기 위하여 현장조건을 재현하여 재성형한 순환골재 다공질 콘크리트 말뚝(RAPP)-점토 혼합토에 대하여 삼축압축시험을 하였다. 삼축압축시험의 공시체는 치환율 15, 35, 60, 100%로 조성, 복합지반의 전단거동 특성을 규명하였다. 또한 현재 연약지반 개량공법 중 모래다짐말뚝(SCP, sand compaction pile)공법과의 비교를 위하여 모래-점토 혼합토의 시험도 실시하였다. 시험결과, RAPP-점토 혼합토의 경우, 내부마찰각은 $18{\sim}34$도의 범위를 나타났으며, 점착력의 경우는 $557.0kPa{\sim}588.0kPa$의 범위를 나타났다. 하지만 모래-점토 혼합토의 강도정수값은 내부마찰각은 $26{\sim}35$도의 범위를 나타났으며, 점착력은 치환율별로 $4.0{\sim}18.0kPa$의 범위로 나타났다.

• 한국철도학회논문집
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• 제20권1호
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• pp.64-75
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• 2017

철도궤도 상부 흙노반은 궤광으로부터 전달된 열차하중을 지지하고 분산하는 기능을 갖는다. 성토체의 일반적인 흙노반은 흙재료를 다짐하여 조성하며 차량 반복하중에 의해 공용중 잔류침하가 발생하는 데 일정부분 기여한다. 흙노반의 잔류침하는 회복불가능한 영구변형이어서 궤도틀림 등 궤도 안전성을 크게 저하시킨다. 그럼에도 불구하고 현재까지 흙노반재료에 대한 역학적 시험을 바탕으로 합리적인 잔류침하 관리기준이 제시된 바 없다. 반면에 흙노반의 현장관리 및 판정기준은 강성평가 또는 현장들밀도시험에 의해서만 이루어지고 있어 불합리하다. 본 연구에서는 흙노반이 경험하는 전단응력비(${\tau}/{\tau}_f$)와 구속압(${\sigma}_3$)을 수치해석을 통해 구하고 이를 반영한 실내 흙노반 영구변형시험방법을 제시하였다. 제시된 시험방법을 이용하여 대표적인 철도건설현장 흙노반 재료로 만든 다짐시편에 대하여 반복삼축시험을 실시하였으며 이로부터 향후 잔류침하의 추정에 활용할 수 있는 기본 영구변형예측모델 모델계수를 구속압 및 전단응력비 수준별로 제시할 수 있었다.

• 한국지반신소재학회논문집
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• 제9권3호
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• pp.29-37
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• 2010

본 연구는 육상과 접해있는 해상에 퇴적된 입자가 매우 균등한 실트섞인 세립질 모래지반의 공학적인 특성을 평가하기 위하여 새만금지역에서 시료를 채취하였다. 채취한 시료에 대하여 상대밀도 시험을 통해 최소 및 최대밀도시험을 하였으며 상대밀도별 사질토의 변형특성과 전단특성을 평가하기 위하여 로우셀압밀시험 및 비배수 삼축압축시험을 실시하였다. 실험결과 상대밀도에 따라서 약간씩 차이는 있지만 새만금지역 해상사질토의 최대 압축 가능한 간극비는 0.88정도이며, 최대 다짐 가능한 상대밀도는 약 71%정도로 평가 되었다. 또한 내부마찰각은 상대밀도의 증가에 따라서 선형적으로 증가하는 양상을 보였으며 기 연구된 군장항에 퇴적된 사질토의 특성과 매우 유사한 전단거동을 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.838-845
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• 2006

Recently construction work in Korea, demands of favorable condition ground had been increased with industrialization acceleration and economic growth. However, because of limited land space, it was so hard to ensure favorable condition grounds that construction work proceeds until soft ground area on plans of road, railroad and industrial complex. In this case, soft ground improvement was required such as a stone column method. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, evaluates the stone columns reinforced by geogrid for settlement reduction and wide range of application of stone columns. Triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate. Then, 3-dimensional numerical analysis were conducted for application of stone column reinforced by geogrid as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on reinforcing depth change of geogrid.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.103-110
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• 2006

When enforced earth is used for the retain wall and four walls, the most important thing would be how to maximize the land utilization. Accordingly, in case of enforced earth, we pile up the minimal height of earth$(20\sim30cm)$ and harden the earth using a static dynamic hardening machine. In this paper, we tried to analyze and. compare the stress transformation characteristics of reinforced weathered granite soil. with geosynthetics when repetitive load is added to the enforced earth structure and when static load is added. The purposes of the study are as follows; 1) To compare and analyze non reinforced weathered granite soil and reinforced weathered granite. soil by executing a unconsolidated-undrained triaxial compression tests. 2) To identify the strength characteristics of weathered granite soil reinforced with geotextile due to the repetitive dynamic loads through comparison of the stress due to the static load and the repetitive dynamic loads.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.362-371
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• 2006

The behaviour characteristics of Granular Compaction Pile(GCP) are mainly governed by the lateral confining pressure mobilized in the matrix soft soil to restrain the bulging failure of the granular compaction pile. The GCP method is most effective in soft soil with untrained shear strength ranging from $15\sim50\;kPa$. However, the efficiency of this method is falling down in the more compressible soil conditions, which does not provide sufficient lateral confinement. In the present study, the GCP method reinforced with uniformly graded permissible concrete is suggested for the extension of application to the soft ground. Also, large triaxial compression tests are conducted on composite- reinforced soil samples for verification of availability of the suggested method and the settlement estimation method of the reinforced GCP is proposed. Further, for the verification of a validity of the proposed method, predicted settlements are compared with results of numerical analyses. Tn addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• 한국지반환경공학회 논문집
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• 제13권9호
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• pp.61-68
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• 2012

본 연구의 주된 목적은 EPS지오폼이 연성포장의 노반재료로 사용될 때 그것의 회복탄성계수를 해석 모델화 하는 것이다. 이 해석모델은 삼축압축 시험으로부터 나온 실험결과를 토대로 만들어졌다. 그리고 이 모델은 원하는 용도에 따라서, 기존의 프로그램을 수정하거나 새로 개발하여 유한요소법을 이용한 연성포장구조를 해석하는데 사용될 수 있다. 또한 본 연구의 결과는 연성포장에서의 현장 연약지반 노상재료의 대체물로서 EPS지오폼은 적합한 것으로 확인되었다.

• Geomechanics and Engineering
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• 제18권5호
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• pp.459-469
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• 2019

It is important to estimate the shear strength of shallow compacted soils as a construction material. A series of constant water content triaxial compression (CWCC) tests under low confining state in this study were performed on compacted geomaterials. For establishing a relationship of the shear strengths between saturated and unsaturated states on compacted geomaterials, the suction stresses were derived by two methods: the conventional suction-measured method and the Suction stress-SWRC Method (SSM). Considering the suction stress as an equivalent confining stress component in the (${\sigma}_{net}$, ${\tau}$) plane, it was found that the peak deviator stress states agree well with the failure line of the saturated state from the triaxial compression test when the SSM is applied to obtain the suction stress. On the other hand, the cavitation phenomenon on the measurement of suction affected the results of the conventional suction-measured method. These results mean that the SSM is distinctly favorable for obtaining the suction value in the CWCC test because the SSM is not restricted by the cavitation phenomenon. It is expected that the application of the SSM would reduce the time required, and the projected cost with the additional equipment such as a pore water measuring device in the CWCC test.

• 한국농공학회논문집
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• 제49권6호
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• pp.87-92
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• 2007

Strain-stress behavior of soil is of importance in dealing with geo-techniques which relate to bearing capacity, slope stability, earth pressure and many geo-technical problems. So understanding mechanism of the behavior and reinforcing soil to the required state has been an issue for many years. This paper presents the possibility of magnetic force in enhancing shear strength. To analyze the reinforcing effect, triaxial compression tests were performed on two sets of steel-sand mixtures, one of which is influenced by permanent magnet, NdFeB. With magnetic force under 50 kPa confining pressure, maximum shear strengths increased according to steel percentages but under 100 kPa, no significant changes in maximum shear strengths occurred. Therefore the analysis by Mohr's circles indicates that magnetic force converts the shearing characteristics of sand into those of clay.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.132-135
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• 2009

In order study, experimental stress-strain relationships were achieved for various suctions by triaxial tests. A failure envelop was occurred on a plane in p-q-$\psi$ space, since the level of matric suction is in the small range. It was found that the failure criteria could be defined uniquely by the Bishop stress and were also independent of matric suctions. At the level of small strain, deformation moduli were evaluated according to matric suctions by fitting to Ramberg-Osgood model. It was found that deformation moduli increase as matric suctions increase.