• Title/Summary/Keyword: 터널내 탄성파탐사

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Development and application of 3D migration techniques for tunnel seismic exploration (터널내 탄성파 탐사의 3차원 구조보정기법 개발 및 현장적용)

  • Choi, Sang-Soon;Han, Byeong-Hyeon;Kim, Jae-Kwon;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.3
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    • pp.247-258
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    • 2004
  • Two 3-dimensional data processing techniques to predict the fractured zone ahead of a tunnel face by the tunnel seismic survey were proposed so that the geometric formation of the fractured zone could be estimated. The first 3-dimensional data processing technique was developed based on the principle of ellipsoid, The input data needed for the 3D migration can be obtained from the 2-dimensional tunnel seismic prediction (TSP) test where the TSP test should be performed in each sidewall of a tunnel. The second 3-dimensional migration technique that was developed based on the concept of wave travel plane was proposed. This technique can be applied when the TSP is operated with sources in one sidewall of a tunnel while the receivers are installed in both sidewalls. New migration technique was applied to an in-situ tunnelling site. The 3-dimensional migration was performed using measured TSP data and its results were compared with the geological investigation results that were monitored during tunnel construction. This comparison revealed that the proposed migration technique could reconstruct the discontinuity planes reasonably well.

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Application of seismic reflection method in the tunnel of Youngdong railroad (Mt. Dongbaek~Dokye) (영동선 동백산-도계간 터널내 반사법 탄성파탐사 적용사례)

  • Kim, Yong-Il;Cho, Sang-Kook;Yang, Jong-Hwa;Kim, Jang-Soo;Lee, Nai-Yong
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.1
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    • pp.89-100
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    • 2003
  • Seismic Reflection Methods (TSP, HSP) have been applied in the junction between 2nd Adit and Main Tunnel (Solan Tunnel) of Youngdiong Railroad (Mt. Dongbaek~Dokye). In this paper, methods and case study will be introduced to predict discontinuties in the tunnel before excavation by the Seismic Reflection Methods (TSP, HSP)and secure construction stability of the tunnel in blasting and excavation.

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Prediction and Evaluation of Rock Mass Condition by Seismic Profiling Method in Tunnel (터널내 탄성파 탐사를 이용한 전방 지질 예측 및 평가)

  • Lee, Jong-Man;Kwak, Hyun-Joon;Kim, Young-Geun;Baek, Ki-Hyun;Cho, Chul-Hyun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.3 no.3
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    • pp.45-56
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    • 2001
  • It is very important to survey in construction for acquiring informations about geological structure which influence the tunnel construction. Usually, TSP(Tunnel Seismic Prediction) one of the seismic survey method in tunnels in Korea has been used for prediction of geological condition ahead of tunnel face, but in this study HSP(Horizontal Seismic Profiling) was used. As a result of field application, we predicted that there exist rock discontinuity such as fault, joints and bedding planes. In addition, RMR value from rock mass evaluation coincided with that from seismic survey for rock condition. We compared with rock classifications and evaluation results for proving.

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A Field Application of Crosshole Seismic Survey to the Detection of Tunnel (터널위치 규명을 위한 시추공 탄성파탐사 현장 응용)

  • 김중열;김유성
    • The Journal of Engineering Geology
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    • v.7 no.1
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    • pp.27-36
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    • 1997
  • This paper shows that crosshole seismic survey allows to detect even a small size of underground tunnel (about 2m$\times$2m). Such a small tunnel (e.g. infiltration tunnel) causes diffraction, as the seismic wave propagates, which results in distinctive variations of traveltime and amplitude of the first arrivals. This effect (or tunnel effect) is a typical indicator for the existence of tunnel and thereby an information about the tunnel location can be obtained. It was shown that the tunnel effect illustrated by numerical modeling (FDM) could be also observed in field measurements. The depth and shape of the tunnel were determined by a simplified processing method based on the use of amplitude variation of the first arrivals. The estimated location of the tunnel was well matched to that of the real tunnel.

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2 Dimensional TSP Modeling Using Finite Element Method (유한 요소법을 이용한 2차원 TSP 모델링)

  • Lee, Hong;Suh, Jung-Hee;Shin, Chang-Soo
    • Geophysics and Geophysical Exploration
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    • v.6 no.1
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    • pp.13-22
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    • 2003
  • TSP (Tunnel Seismic Profiling) survey is a technique for imaging and characterizing geological structures ahead of a tunnel face. The seismic modeling algorithm and the synthetic data could be helpful for TSP surveys. However, there is few algorithm to describe the propagation of the elastic waves around the tunnel. In this study, existing 2-dimensional seismic modeling algorithm using finite element method was modified to make a suitable algorithm for TSP modeling. Using this algorithm, TSP modeling was practiced in some models. And the synthetic data was analyzed to examine the propagation characteristics of the elastic waves. First of all, the modeling for the homogeneous tunnel model was practiced to examine the propagation characteristics of the direct waves in the vicinity of the tunnel. And the algorithm was applied to some models having reflector which is perpendicular or parallel to the excavation direction. From these, the propagation characteristics of the reflected waves were examined. Furthermore, two source-receiver arrays were used in respective models to investigate the properties of the two arrays. These modeling algorithm and synthetic data could be helpful in interpreting TSP survey data, developing inversion algorithm and designing new source-receiver arrays.

3D analysis of fracture zones ahead of tunnel face using seismic reflection (반사 탄성파를 이용한 터널막장 전방 파쇄대의 3차원적 예측)

  • Lee, In-Mo;Choi, Sang-Soon;Kim, Si-Tak;Kim, Chang-Ki;Jun, Jea-Sung
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.4 no.4
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    • pp.301-317
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    • 2002
  • Recently, a geophysical exploration technology is frequently utilized in the civil engineering field as well as in the resource exploration. It might be important for civil engineers to understand the fundamental theory of seismic survey and limitation of the technique when utilizing these techniques in the civil engineering field. A 3-dimensional migration technique based on the principle of ellipsoid to predict the fractured zone ahead of tunnel face utilizing the tunnel seismic survey was proposed so that the geometry of the fractured zone can be estimated, i.e. the angle between tunnel axis and discontinuity zone, and the dip. Moreover, a numerical analysis technique to simulate the TSP (Tunnel Seismic Prediction) test was proposed in this paper. Based on parametric studies, the best element size, the analysis time step, and the dynamic characteristics of pressure source were suggested to guarantee the stability and accuracy of numerical solution. Example problems on a hypothetical site showed the possibility that the 3-dimensional migration technique proposed in this paper appropriately estimate the 3D-geometry of fractures ahead of tunnel face.

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Application of linear-array microtremor surveys for rock mass classification in urban tunnel design (도심지 터널 암반분류를 위한 선형배열 상시진동 탄성파 탐사 적용)

  • Cha, Young-Ho;Kang, Jong-Suk;Jo, Churl-Hyun
    • Geophysics and Geophysical Exploration
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    • v.9 no.1
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    • pp.108-113
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    • 2006
  • Urban conditions, such as existing underground facilities and ambient noise due to cultural activity, restrict the general application of conventional geophysical techniques. At a tunnelling site in an urban area along an existing railroad, we used the refraction microtremor (REMI) technique (Louie, 2001) as an alternative way to get geotechnical information. The REMI method uses ambient noise recorded by standard refraction equipment and a linear geophone array to derive a shear-wave velocity profile. In the inversion procedure, the Rayleigh wave dispersion curve is picked from a wavefield transformation, and iteratively modelled to get the S-wave velocity structure. The REMI survey was carried out along the line of the planned railway tunnel. At this site vibrations from trains and cars provided strong seismic sources that allowed REMI to be very effective. The objective of the survey was to evaluate the rock mass rating (RMR), using shear-wave velocity information from REMI. First, the relation between uniaxial compressive strength, which is a component of the RMR, and shear-wave velocity from laboratory tests was studied to learn whether shear-wave velocity and RMR are closely related. Then Suspension PS (SPS) logging was performed in selected boreholes along the profile, in order to draw out the quantitative relation between the shear-wave velocity from SPS logging and the RMR determined from inspection of core from the same boreholes. In these tests, shear-wave velocity showed fairly good correlation with RMR. A good relation between shear-wave velocity from REMI and RMR could be obtained, so it is possible to estimate the RMR of the entire profile for use in design of the underground tunnel.

Use of the Tunnel Seismic Prediction Method for Construction of Spillways at Juam Dam (터널 내 탄성파탐사(TSP)기법의 주암댐 보조여수로 적용 사례 연구)

  • Bae, Jongsoem;Chang, Chandong
    • The Journal of Engineering Geology
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    • v.23 no.1
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    • pp.67-77
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    • 2013
  • We conducted a Tunnel Seismic Prediction (TSP) survey in a spillway tunnel at Juam Dam to predict the locations of major discontinuities ahead of the tunnel face. We compared the results of the TSP survey with those from pre-construction inspections (including a surface resistivity survey and borehole investigations) as well as with direct tunnel-face mapping during excavation. The TSP method predicted the locations of major fracture zones that were unnoticed in the pre-construction inspections. The reinforcement patterns planned on the basis of pre-construction inspections were changed on the basis of the TSP results. The results demonstrate that TSP surveys are a cost-effective and reliably accurate method of predicting the locations of fracture zones. Although the TSP method has some limitations, these results suggest that the method is generally useful for predicting geological conditions prior to tunnel face construction.

Application of Seismic Reflection Method in the tunnel of Youngdong Railroad(Mt. Dongbaek~Dokye) (영동선 동백산-도계간 터널내 반사법 탄성파탐사 적용사례)

  • 김용일;윤영훈;조상국;양종화;김장수;이내용
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.696-708
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    • 2002
  • Seismic Reflection Methods(TSP, HSP) have been applied in the junction between 2nd Adit and Main Tunnel (Solan Tunnel) of Youngdiong Railroad(Mt. Dongbaek∼Dokye). In this paper, methods and case study will be introduced to predict discontinuties in the tunnel before excavation by the Seismic Reflection Methods(TSP, HSP)and secure construction stability of the tunnel in blasting and excavation.

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