Predicting ground conditions ahead of the tunnel face by vector orientation analysis

Jeon, Je-Sung; Martin, C. Derek; Chan, Dave; Kim, J.S.

doi:10.1016/j.tust.2005.01.002

Cited by 23 publications

(11 citation statements)

References 2 publications

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“…The estimated length of the advance core depending only on the mechanical characteristics of the ground is 4 to 6 times the value of R (Lunardi, 2000). In a homogeneous ground condition, when a weak zone is placed 1.0 R ahead of the tunnel face, the vertical displacement of the tunnel face changes rapidly (Jeon et al, 2005;Baek et al, 2006). Therefore, the influence range of the hydrological characteristics of the hazardous zone on the stability of the face is greater than that of the mechanical characteristics.…”

Section: Effects Of the Seepage Force Induced By A Hazardous Zone On mentioning

confidence: 99%

“…Schubert and Steindorfer (1998), Jeon et al (2005), and Baek et al (2006) carried out studies of the stability and behavior of tunnels with localized fracture zones such as faults. However, few studies exist regarding the effects of high water pressure on the stability of a tunnel face affected by a fracture zone ahead of the tunnel.…”

Section: Introductionmentioning

confidence: 99%

“…Lunardi's Advance Core Concept(Jeon et al, 2005) Extrusion of the Tunnel Face Induced by the Failure of the Advance Core…”

mentioning

confidence: 99%

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Effect of a front high hydraulic conductivity zone on hydrological behavior of subsea tunnels

et al. 2010

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This study focuses on the hydrological behavior of the ground ahead of a tunnel face. A localized high hydraulic conductivity zone with high water pressure is denoted as a hazardous zone. To analyze the impact of the hazardous zone on the face stability, a new indicator (TSR: the ratio of the driving force to the resisting force) is proposed on the basis of the "advance core" concept (Lunardi, 2000). A series of three-dimensional steady-state seepage analyses are performed to estimate the distribution of the TSR of the ground ahead of the tunnel face. The analyses results show that the hydrostatic pore water pressure acts on the most of the hazardous zones throughout all of the tunnelling stages. When the distance between the tunnel face and the hazardous zone (d h ) value is approximately five times the excavated tunnel radius, the influence of the hazardous zone increases rapidly.

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Section: Effects Of the Seepage Force Induced By A Hazardous Zone On mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of a front high hydraulic conductivity zone on hydrological behavior of subsea tunnels

et al. 2010

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“…The vector orientation technique is used to assess the ground conditions ahead of an advancing tunnel with considerable amount of success (Jeon and Martin 2005). The combination of the vector orientation analysis and the use of GeoFit software (Sellner 2002) allow the detection of deviations from 'normal' system behavior in time.…”

Section: Literature Reviewmentioning

confidence: 99%

Prediction of Ground Conditions Ahead of an Advancing Tunnel Face by Quantification of Vector Orientation

Goswami

Sharma

2014

Tunneling and Underground Construction

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Observation and Measurement of displacements at the crown of the tunnel is an integral part of NATM (New Austrian Tunneling Method) in complex rock masses to verify the construction parameters, support systems and safety requirements. However, the prediction of ground conditions ahead of an advancing tunnel face is also an application, often explored less in the field by site engineers. Literature suggests displacement vector orientation as a good indicator of weak ground or fault/shear zones ahead of the tunnel face. There has been no quantification between the vector orientation and the properties of the weaker ground ahead. An attempt is made to quantify the effect of the properties of the weaker ground on the vector orientation numerically. The model results are initially compared with analytical solutions, followed by benchmarking with the results of other researchers. The factors which affect the vector orientation are the diameter of the tunnel, stiffness ratio of the rocks and insitu stress ratio. The effect of each of these parameters is studied independently. A correlation between the vector orientation and the variation in ground conditions is then established to predict the properties of the weaker ground ahead of the advancing tunnel face.

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“…The influences of the length of a soft zone embedded between stiff ground, as well as the stiffness differences are outlined in [15] and [16]. The results originate from the evaluation of numerical 3D simulations.…”

Section: Displacement Vector Orientationmentioning

confidence: 99%

Analysis of Tunnel Displacements for the Geotechnical Short Term Prediction

Grossauer

Schubert

2008

Geomechanics and Tunnelling

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Measurement of displacements in tunnels is primarily used for the assessment of the stabilization process and the verification of the system behaviour. In addition the displacement data can be used for the prediction of changing ground conditions ahead of the face. For this purpose, the evaluation of displacement vector orientation turned out to be the most appropriate method. Several authors showed the influence of the excavation on the stress and displacement field when tunnelling through zones of different stiffness. One of the main findings was that the displacement vector orientation significantly changes when the excavation approaches ground with different deformability. Hence, it was concluded that the development of the spatial orientation of the displacement vector can be used for the prediction of the ground conditions ahead of the face. The main results of the investigations performed are summarized in this paper. The evaluation of data from three different case histories is shown in order to encourage the use of advanced displacement data evaluation. Die Analyse der Tunnelverschiebungen als Instrument für die geotechnische PrognoseVerschiebungsmessdaten im Tunnelbau werden hauptsächlich für die Beurteilung des Stabilisierungsprozesses und zur Über-prüfung des Systemverhaltens verwendet. Zusätzlich können diese Daten auch für die Prognose von Änderungen in den Gebirgsverhältnissen vor der Ortsbrust benutzt werden. Die Auswertung der Orientierung der Verschiebungsvektoren hat sich dabei als die am besten geeignete Methode herausgestellt. Für einen Vortrieb in einem Gebirge mit Bereichen unterschiedlicher Steifigkeit hat eine Reihe von Autoren den Einfluss auf das Spannungsund Verschiebungsfeld untersucht. Als eine der wichtigsten Feststellungen dabei hat sich erwiesen, dass sich die Orientierung des Verschiebungsvektors mit der Annäherung an einen Gebirgsbereich mit unterschiedlicher Verformbarkeit deutlich ändert. Man kam zum Schluss, dass der Verlauf der räumlichen Orientierung der Verschiebungsvektoren für die Prognose der Gebirgsverhältnisse vor der Ortsbrust herangezogen werden kann. Die wichtigsten Ergebnisse dieser Untersuchungen werden in diesem Beitrag zusammengefasst. Die Anwendung der modernen und weitergehenden Messdatenauswertung wird mit Beispielen der Verschiebungsdaten von drei Fallstudien demonstriert. IntroductionSince nearly twenty years absolute displacement monitoring is an essential part of modern tunnelling. Especially in complex and difficult ground conditions, absolute displacement data provide valuable information on the response of the ground to the excavation process.With the increased use of these data, different displacement data evaluation methods have evolved. Initially rather simple methods such as time-displacement plots were utilized for the evaluation of the tunnel stabilization process Following the table presented in [5], the evaluation of the spatial vector orientation is one of the most appropriate methods in order to predict the ground conditions ahead of the fac...

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Predicting ground conditions ahead of the tunnel face by vector orientation analysis

Cited by 23 publications

References 2 publications

Effect of a front high hydraulic conductivity zone on hydrological behavior of subsea tunnels

Effect of a front high hydraulic conductivity zone on hydrological behavior of subsea tunnels

Prediction of Ground Conditions Ahead of an Advancing Tunnel Face by Quantification of Vector Orientation

Analysis of Tunnel Displacements for the Geotechnical Short Term Prediction

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