• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.261-266
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• 1997

• 토지주택연구
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• 제3권4호
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• pp.389-397
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• 2012

In this study, crosshole seismic test, donwhole seismic test, SPT uphole test, and suspension PS logging (SPS logging) were conducted and the shear wave velocities of these tests were compared. The test demonstrated the following result: Downhole tests showed similar results compared to those of crosshole tests, which is known to be relatively accurate. SPS logging showed reliable results in the case of no casing, i.e. in the rock mass, while, in the case of soil ground, its values were lower or higher than those of other tests. SPT-uphole tests showed similar results in the soil ground and upper area of rock mass compared to other methods. However, reliable results could not be obtained from these tests because SPT sampler could not penetrate into the rock mass for the tests.

• 지질공학
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• 제12권2호
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• pp.127-135
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• 2002

시추공영상자료와 시추조사에서의 RQD자료 및 완전파형음파검층에 의해 측정된 탄성파속도를 이용하여 각 암상에서의 탄성파속도와 RQD와의 상관관계를 검토하였다. 탄성파속도와 절리틈과의 상관관계는 유성일대의 화강암과 팔당일대의 호상 편마암에서 높은 상관성을 보인 반면, 사북일대 퇴적암에서 상관성이 없는 것으로 나타났다. 사북지역의 퇴적암에서는 상관성이 없고, 특히 누적 절리틈이 0∼20mm구간에서 탄성파속도 분포의 분산이 크게 나타나며, 이는 탄질 세일의 파쇄구간이 넓게 분포하여 절리틈 크기의 측정에 무리가 있었을 것으로 추측된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.84-90
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• 2009

An integrity testing for stone columns was attempted using crosshole S-wave logging. The method is conceptionally quite similar to the crosshole sonic logging (CSL) for drilled piers. The critical difference in the logging is the use of s-wave rather than p-wave, which is used in CSL, because s-wave is the only wave sensing the stiffness of slower unbounded materials than water. An electro-mechanical source, which can generate reversed S-wave signals, was utilized in the logging. The stone column was delineated from the S-wave travel times across the stone column, and taking S-wave velocities of the crushed stone and surrounding soil into account. The volume calculated from the diametrical variance delineated is very close to the actual quantity of the stone filled.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 암반역학위원회 학술세미나 논문집
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• pp.119-137
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• 2003

Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity Is widely used In determination of rock quality in road and railway tunnel design. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test In laboratory, such as uniaxial compressive strength(UCS), P wave velocity, Young's modulus and electrical resistivity. We correlate each test results and we found out that electrical resistivity has exponentially related to UCS and P wave velocity and linearly related to Young's modulus. And we accomplished electrical resistivity survey in field site and carried out electrical resistivity togging at In-situ area. Also we performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to rock classification results. We found out that electrical resistivity logging data are highly correlate to RQD, Q and RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RQD, Q and RMR.

• 한국지반공학회논문집
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• 제20권6호
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• pp.51-59
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• 2004

공학적 물성치로서의 저변형율에서의 전단탄성계수의 결정은 다양한 토목분야에서 매우 중요하다. 본 논문에서는 저변형율에서의 전단탄성계수를 결정하기 위하여 개발된 HWAW(Harmonic Wavelet Analysis of Wave)방법을 이용한 지반조사기법의 실제 현장에서의 타당성을 검증하기 위하여 두 곳의 현장에 HWAW방법을 적용하였다. HWAW방법을 검증하기 위하여 동일한 현장에서 수행된 SASW시험과 PS-Suspension Logging 실험의 결과와 비교하였다. 이를 통하여 HWAW방법이 배경잡음과 지반의 횡방향 불균일성에 의한 오류를 기존 방법에 비하여 최소화 할 수 있으며, 국부적이며 정밀한 대상지반의 실제 전단파 속도 주상도를 매우 효과적으로 결정할 수 있음을 확인할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.352-359
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• 2005

In this study, seismic refraction survey and MASW at dam crest and down-hole test and cross hole test in the boring holes located in dam crest through the core are performed to fin out dynamic material properties, are needed to evaluate dynamic safety of rockfill dam using dynamic analysis method. From the field test and geophysical exploration, applied such as above, p-wave and s-wave velocity profile of each layer of dam body. Dynamic material properties, such as elastic modulus, shear modulus, poissong's ration, are obtained from p-wave and s-wave velocity profile and density profile from formation density logging test.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1415-1426
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• 2008

Stone columns, locally called "GCP (granular compaction pile)" can be used to improve strength and resistance against lateral movement of a foundation soil like rigid piles and piers. Also installation of such a discrete column facilitates drainage, and densifies and reinforces the soil in the sense of ground improvement. The integrity of the GCP has been indirectly controlled with the records of each batch including depth and the quantity of stone filled. An integrity testing was attempted using crosshole S-wave logging. The method is conceptionally same as the crosshole sonic logging (CSL) for drilled piers. The only and critical difference is that S-wave should be used in the logging, because P-wave velocity of the stone column is less than that of ground water. The crosshole sonic logger does not have the capability to measure S-wave propagating through the skeleton of crushed stone. An electro-mechanical source, which can generate either P- or SH-waves, and a 1-D geophone were used to measure SH-waves. Two 76mm diameter cased boreholes were installed 1 meter apart across the nominal 700mm diameter stone column. At every 10cm of depth, shear wave was measured across the stone column. One more borehole was also installed 1 meter outward from the one of the above boreholes to measure the shear wave profile of the surrounding soil. The diametric variation of the stone column with respect to depth was evaluated from the shear wave arrival times across the stone column, and shear wave velocities of crushed stone and surrounding soil. The volume calculated with these variational diameters is very close to the actual quantity of the stone filled.

• 한국지반공학회논문집
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• 제24권10호
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• pp.161-174
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• 2008

국내 점성토 지반 및 풍화토 지반의 전단파속도 특성을 파악하기 위하여 표준관입시험(SPT), 부유형 PS 속도검층(SPS) 및 다운홀 등의 시험을 수행하였으며, SPT와 SPS 속도검층 결과로부터 지층별 전단파 속도를 분석하였다. 본 연구대상 지역에서 측정된 전단파 속도를 점성토와 풍화토로 나누어 분석하여 지반강도와 전단파속도와의 상관관계로부터 경험식을 제안할 수 있었는데, 점성토에서는 여러 학자들에 의하여 기존에 제안된 경험식과 유사한 결과를 나타내었으나 풍화토에서는 기존 경험식에 의한 값과 연구대상 지역에서 측정한 실측값과는 다소 차이가 있음을 확인하였다. 아울러 연구 대상지역에 대한 전단파 속도의 깊이에 따른 영향을 제시하였고 이 결과를 Ohta 등(1978)의 경험식과 비교, 검토하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.656-665
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• 2010

Shear modulus has been recognized as one of the important soil properties in dynamic analysis of ground and can be calculated from in situ measurement of shear wave velocity. Field seismic tests are the most accurate but expensive methods to investigate dynamic ground characteristics. Due to that reason, empirical equations for estimating the shear wave velocity are widely used rather than conducting in-situ tests. The most common equations are based on the N value obtained in conjuctions with a standard penetration test. In this paper, the field datas of standard penetration test and suspension PS logging measured in 126 sites of Korea were summarized and the correlation equations between N value and shear wave velocity are suggested.