• Title/Summary/Keyword: Crosshole

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A Fast Crosshole Electromagnetic Tomography Using Localized Nonlinear Approximation

  • Kim, Hee-Joon;Lee, Ki-Ha;Mike-Wilt
    • Proceedings of the KSEEG Conference
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    • 2003.04a
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    • pp.150-153
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    • 2003
  • High-resolution imaging of electrical conductivity has been the subject of many studies in crosshole tomography using electromagnetic (EM) fields (Zhou et al., 1993; Wilt et al., 1995; Alumbaugh and Morrison, 1995; Newman, 1995; Alumbaugh and Newman, 1997). Although the theoretical understanding and associated field practices for crosshole EM methods are relatively mature, fast and stable imaging of crosshole EM data is still a challenging problem. (omitted)

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Logging for a Stone Column Using Crosshole Seismic Testing (크로스홀 탄성파 시험을 이용한 쇄석다짐말뚝의 검측)

  • Kim, Hak-Sung;Park, Chul-Soo;Lee, Tae-Hee;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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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.

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Development and Application of a Source for Crosshole Seismic Method to Determine Body Wave Velocity with Depth at Multi-layered Sites (다층 구성 부지에서의 깊이별 실체파 속도의 결정을 위한 시추공간 탄성파 탐사 발진 장치 개발 및 적용)

  • Sun, Chang-Guk;Mok, Young-Jin
    • Geophysics and Geophysical Exploration
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    • v.9 no.3
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    • pp.193-206
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    • 2006
  • Among various borehole seismic testing techniques for determining body wave velocity, crosshole seismic method has been known as one of the most suitable technique for evaluating reliably geotechnical dynamic properties. In this study, to perform successfully the crosshole seismic test for rock as well as soil layers regardless of the groundwater level, multi-purposed spring-loaded source which impact horizontally a subsurface ground in vertical borehole was developed and applied at major facility sites in Korea. The geotechnical dynamic properties were evaluated by determining efficiently the body wave velocities such as shear wave velocity and compressional wave velocity from the horizontally impacted crosshole seismic tests at study sites, and were provided as the fundamental parameters for the seismic performance evaluation and seismic design of the target facilities.

Logging for Diametric Variation of Granular Compaction Pile Using Crosshole Seismic Tests (크로스홀 탄성파 시험을 이용한 쇄석다짐말뚝의 시공직경 검측)

  • Park, Chul-Soo;Jung, Jae-Woo;Kim, Hak-Sung;Kim, Eun-Jung;Mok, Young-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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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.

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A Comparative Study on Borehole Seismic Test Methods for Site Classification

  • Jung, Jong-Suk;Sim, Youngjong;Park, Jong-Bae;Park, Yong-Boo
    • Land and Housing Review
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    • v.3 no.4
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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.

Borehole Seismics: Review and Its Application to Civil Engineering (시추공 탄성파탐사 및 이의 토목공학적 응용)

  • Chang Hyun-Sam;Lim Hae-Ryong;Hong Jae-Ho
    • 한국지구물리탐사학회:학술대회논문집
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    • 1999.08a
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    • pp.176-201
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    • 1999
  • Principles, data acquisition, data processing of four frequently used borehole seismic methods, i.e., downhole seismic, vertical seismic profiling(VSP), crosshole seismic, and seismic tomography, are reviewed briefly. Field data examples are presented and their application to civil engineering area was also discussed.

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Mechanical Characteristics of Railway Subgrade Materials Experiencing Mud-Pumping (분니가 발생한 철도 노반토의 역학적 특성)

  • 목영진;황선근;이성혁
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.415-422
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    • 1999
  • A series of crosshole tests was conducted to evaluate the mechanical characteristics of railway subgrade materials which has been experiencing mud-pumping. The shear wave velocity profiles of mud-pumped sites were compared with those of adjacent intact sites. The shear wave velocities of mud-pumped layers are less than 150 m/sec.

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Evaluation of Dynamic Soil Properties Using Dynamic Tests (동적시험에 의한 동적지반특성 평가)

  • Lee, Myung Jae;Shin, Jong Ho;Kang, Ki Young;Chon, Chun Su
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.10 no.2
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    • pp.91-102
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    • 1990
  • The representative tests in this study are performed at a selected site which has the soil layers to analyze the safety and economy of the dynamic analysis for the variable soil conditions. Crosshole test and downhole test of small strain level tests and triaxial test of large strain level test are performed in the soil layers, and in the rock layers, crosshole test and downhole in-situ tests and laboratory sonic test are performed to measure the dynamic shear modulus, damping ratio, and Poisson$\acute{s}$ ratio of the soil and the rock. The correlations between the dynamic soil properties from the tests and the basic soil properties are determined through the regression analysis. The representative design value of the soil is determined by probability analysis of the test results. It is determined from the nonlinear stress-strain model in soils, and the value at small strain level is computed in rocks according to the distribution of the type of soils and the affecting variables. The constitutive value is systematized to be utilized in the analysis of the test results, and computation of the input soil data.

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Logging for a Stone Column Using Crosshole Seismic Testing (크로스홀 탄성파 시험을 이용한 쇄석말뚝의 검측)

  • Kim, Hak-Sung;Mok, Young-Jin
    • International Journal of Highway Engineering
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    • v.12 no.4
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    • pp.139-145
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    • 2010
  • 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 swave is the only wave sensing the stiffness of slower unbounded materials than water. An electro-mechanical source, which can generate reversed Swave signals, was utilized in the logging. The stone column was delineated using the S-wave travel times across the stone column, the S-wave velocity profile of the crushed stone($V_{cs}$-profile) and that of surrounding soil($V_s$-profile). In the calculation of $V_{cs}$-profile of the crushed stone, its friction angle and Ko (coefficient of lateral earth pressure at rest) are recommended to be used. The calculation of the column diameter is not much affected by the values of friction angle and Ko.