- Email: [email protected]
Monitoring of Transport Tunnel Deformation at the Construction Stage
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 189 (2017) 417 – 420
Transportation Geotechnics and Geoecology, TGG 2017, 17-19 May 2017, Saint Petersburg, Russia
Monitoring of transport tunnel deformation at the construction stage M.Y. Bryna, D.A. Afonina, N.N. Bogomolovaa,*, A.A. Nikitchina a
Moskovskiy pr., 9, St.Petersburg 190031, Russia
Abstract The analysis of normative documents related to geodetic support of transport tunnel construction showed that for now there are no integral monitoring methods providing surface tunnel structure observation. Therefore, the authors substantiate a new technological scheme of geodetic monitoring of portal parts of a tunnel under construction. To collect data about displacements of tunnel portal structures it is suggested that control points should be fixed by reflective tape or rotating prisms, and their coordinates should be located in an object’s coordinate system. It is suggested that an original geodetic base should be fixed as geodetic points of forced centering out of zone of virtual deformations. Deformation control benchmarks heights should be measured by trigonometric leveling. It is shown that RMS error in measuring the heights of points of geodetic monitoring network should not exceed 4mm. It is found that required accuracy in network building can be provided by III class leveling. To collect data about the depth of weak soils, located close to tunnel portals, as well as the borderlines of their sliding, it is for the first time suggested that surveys should be conducted using borehole inclinometer. The research proves that on pre-portal sites boreholes should be placed close to the group of deformation control benchmarks. © 2017 The Authors. Published by Elsevier Ltd. © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and (http://creativecommons.org/licenses/by-nc-nd/4.0/). Geoecology. Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and Geoecology Keywords: geodetic monitoring, transport tunnels.
Introduction Tunnels are considered to be the most complicated and highly-priced long-life transport engineering structures. According to [1] railway and motorway tunnels should be referred to I high level of structure responsibility, failures of which may lead to severe economic, social and environmental consequences. *
Tel.: +7-921-889-69-27. E-mail address:[email protected].
1877-7058 © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and Geoecology
doi:10.1016/j.proeng.2017.05.066
418
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
Nowadays transport tunnel construction is, as a rule, attended by the need of organizing research-technical support of tunneling works. It is supposed to provide work safety by means of deformation monitoring, which is especially up-to-date in restrained urban conditions. While constructing and operating tunnels the following deformations should be considered: x Of a construction object itself; x Deformations of buildings and structures located in the area of an underground structure influence; x Deformations of retaining walls and adjoining soil mass In general, the term “deformation” means change in the shape of an observed object. In geodetic practice deformation is considered as change of an object location with relation to an original one. Modern geodetic surveys over structure control points displacements are performed establishing coordinates and heights of deformation benchmarks, fixed as tape reflectors or rotating prisms [2]. Structure control points change their location after the structure and are situated in places of possible deformation of a structure. In tunnels such places may be joints between cuts while concreting a tunnel lining, zones of carst cavities or harsh hydrogeological conditions, top of a tunnel arch part etc [3]. At the daylight surface such areas are expansion joints of portal structures, corners of buildings of surrounding development, property lines of soils having different strength properties etc. Deformation benchmarks together are geodetic deformation network, best reflecting behavior of deformation processes while constructing a tunnel. Depending on the kind of determined deformation, deformation benchmarks can be plan benchmarks, height benchmarks and plan-height benchmarks. Let’s analyze the stages of the proposed methods. While constructing a tunnel geodetic monitoring requires making a geodetic control network, points of which must be fixed securely. In each case it is necessary to make a preliminary calculation of the accuracy of deformation benchmarks and control network points location [4]. Tunnel structure displacements are supposed to be obtained with the use of high-accuracy total station and system of reflecting tapes, fixed on tunnel critical structures (piles, capping grillage, temporary supports, final tunnel lining). To determine the state of temporary supports and tunnel permanent lining we propose to measure tunnel contour displacements caused by rock pressure, hydrostatics and temperature action. Measuring transverse and horizontal distances between benchmarks by coordinate method, such kinds of deformation as compression, longitudinal and transverse displacement (Fig.1). After analyzing graphical and numerical results of measurements it is possible to estimate the state of tunnel structures.
Fig. 1 Location of deformation benchmarks on tunnel temporary supports С1, С2, С3, С4, СV – deformation benchmarks; L1-L6 – measured distances between deformation benchmarks.
419
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
Deformations in soil massive, cut by a tunnel, may be caused by not only mining works, but also landslide processes. That’s why within geodetic monitoring of daylight surface together with high-accuracy geodetic equipment it is efficient to use borehole inclinometers, giving necessary information of mass layer-by-layer movements in the area of tunnel mine allotment. The inclinometer – is an instrument which determines the inclination and direction of a drill-hole to control its spatial position [6]. An inclinometer usually consists of inclinometer sonde and data output device. Inclinometers are widely-used in gas and oil industry where they are used for borehole curving control. The result of inclinometric survey is information about soil slide boundary and values of horizontal displacements of rock formations. Boreholes are proposed to be placed evenly along the whole length of a tunnel. At near-entrance sites inclinometric borehole should be placed close to the group of deformation benchmarks (5-6 pcs.). After collecting field-survey information it is necessary to conduct a statistical analysis of the measured data [7]. At the first stage we propose to exclude rough mistakes using analysis for monotonicity of measurement series. At the second stage in order to determine the accuracy of measured values and directions it is efficient to use correlation analysis of inclinometric measurements results and measurements taken with total station. Examining correlation relationships between displacements G of deformation benchmarks and O of inclinometric borehole, positioned close to group of benchmarks, makes it possible to evaluate the reliability of measurements and draw a conclusion about the quality of field works [8,9]. Direct correlation shows that there are no rough mistakes in measurements, in correctness of choice of deformation benchmarks and inclinometric boreholes positioning. Positive coefficients of correlation rGO close to 1, not only confirm reliability in determining values and directions of displacements, but also provide the basis for forecasting [11,12]. As G variable we propose to take displacement value, obtained after tacheometric measurements (for each measurement cycle G 'x2 'y2 , where 'x , 'y – motions of reflective tape in x and y respectively in mm), as O variable – motions, taken by inclinometer sonde (mm). Pair coefficient of correlation can be calculated by: rGO
¦
n
i 1
¦
n
i 1
(G i G )(Oi O )
(G i G ) ( 2
¦
n
i 1
(Oi O )
,
(1)
2
where G i – results of measurements using total station; G – average in first sample; Oi – results of measurements using borehole inclinometer; O – average in second sample. Monitoring involves deformation behavior forecasting. To select a suitable forecast model we propose to take measurement results as time series with their following decomposition into components. As a rule, the simplest mathematical model, describing a time series, is a sum [13]: (2) X T M T ST YT , where M T – systematic component, describing the law of variation of process in time, trend; ST – regular composition oscillating about trend (seasonality); YT – random component. Trend reflects main tendency of variation of deformation dimensions in time. The most preferable practical method of selection of a suitable polynomial degree is the selection by the smallest sum of squared deviations of a theoretical curve from an empirical one. Herewith the following condition should be fulfilled: ( yi yi ) 2 o min , (3)
¦
where yi – values of time series, obtained during experiment, yi – theoretical values, obtained by calculation. Along with trend component a time series contains seasonal and random components [14]. While examining regular seasonal component in the context of tunnel deformation monitoring, it is clear that in order to develop this component part one should have observations of at least one-year period, because oscillation period is one year. This condition contradicts principal tasks of monitoring: to have a reliable picture of deformation process state at the time of tunneling and to have a possibility to make a reliable several stages forecast. Hence, it does not seem possible to find seasonal factor while analyzing tunnel deformations at the time of its construction. Furthermore, after distinguishing the trend time series decomposition comes down to the analysis of distribution law of series random component. If normalcy of distribution of residues is confirmed, one should make a forecast and
420
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
assess it. Monitoring results are important to estimate tunneling dimensions (speed, tolerance for final lining lag) at the time of tunnel construction [15]. Consequently, forecast, based on monitoring results, should consider main tendencies of deformation processes and have a short-term lead period. Within these monitoring methods in order to make a short-term forecast of deformations we suggest using extrapolation of time series by tendency. Conclusions During construction an engineering company, consulting the results of geodetic monitoring, takes a decision if they should continue work within typical cross-section of a tunnel, confirmed by the project, or choose an another section under the influence of conditions of a real situation, which had not been found at the stage of engineering survey and because of that reason were not reflected in design documents. While tunneling in cohesive soils deformation processes go slowly, steadily and are characterized by constantly increasing size. Continuous analysis of temporal and spatial development of these processes makes it possible to optimize planning of actions which should be carried out in the area of bottom-hole front and in tunneling way itself to prevent a construction process from emergencies and to increase drilling speed.
References [1]. Construction codes and regulations «Motorway and railway tunnels». SNiP 32-04-97, p.6. М.: Gosstroy, 1997. [2]. Bezrodniy, K.P. An advanced underground imaging radar / K.P. Bezrodniy, V.B. Boltinzev, V.M. Efanov, V.N. Iljakhin, M.G. Tolstobrov / Proceedings of the World Tunnel Congress '99. –Norway, Oslo, 1999. – P. 31-34. [3]. Chapman, D. Introduction to tunnel construction / D. Chapman, N. Metje, A. Stärk / New York: Spon Press, 2010. – P. 417. [4]. Gairns, C. Development of a semi-automated system for structural monitoring using a reflectorless total station: thesis for the degree of master of science. Department of geodesy and geomatics engineering, University of New Brunswick, Canada 2008, 117 p. [5]. Kuang, S. L. Geodetic network analysis and optimal design: concepts and applications / S. L. Kuang. – Chelsea, Michigan: Ann Arbor Press, Inc., 1996. – 368 p. [6]. Schofield, W. Engineering surveying / W. Schofield, M. Breach / Oxford: Linacre House, 2007. – P. 367. [7]. Schäfer, T. Deformation measurement using terrestrial laser scanning at the hydropower station of Gabeikovo / T. Schäfer // INGEO 2004 and regional central and eastern european conference on engineering surveying, Bratislava, Slovakia, Novermber, 11-13, 2004. [8]. Schneider, D. Terrestrial laser scanning for area based deformation analysis of towers and water damns 3rd IAG / D. Schneider // 12th FIG Symposium, Baden, May 22-24, 2006. [9]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geodetic works for construction of the second stage of the Mariinsky theatre in St. Petersburg // Safety of train traffic: Proceedings of the 12th international conference. – Мoscow, 2011 P. 20-21. [10]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geodetic works for construction of the underground part of the second stage of the Mariinsky theatre in St. Petersburg // Proceedings of the Mining Institute. – St. Petersburg, 2012. Vol. 199. P. 329-333. [11]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geoinformational monitoring for construction of the second stage of the Mariinsky theatre in St. Petersburg // The latest achievements in geodesy, geomatics and land development – European experience: Proceedings of the 8th international conference. – Chernigov, 2012. #8. P. 190-193. [12]. М. Kendall, А. Stewart Multivariate statistical analysis and time series, М. : Nauka, 1976. P. 506. [13]. G.А. Medvedev, V.А. Morozov Computer practicum on time series analysis [Electronic resourse]: Manual. Minsk.: «Electronic book BSU», 2003. P. 18.
ScienceDirect Procedia Engineering 189 (2017) 417 – 420
Transportation Geotechnics and Geoecology, TGG 2017, 17-19 May 2017, Saint Petersburg, Russia
Monitoring of transport tunnel deformation at the construction stage M.Y. Bryna, D.A. Afonina, N.N. Bogomolovaa,*, A.A. Nikitchina a
Moskovskiy pr., 9, St.Petersburg 190031, Russia
Abstract The analysis of normative documents related to geodetic support of transport tunnel construction showed that for now there are no integral monitoring methods providing surface tunnel structure observation. Therefore, the authors substantiate a new technological scheme of geodetic monitoring of portal parts of a tunnel under construction. To collect data about displacements of tunnel portal structures it is suggested that control points should be fixed by reflective tape or rotating prisms, and their coordinates should be located in an object’s coordinate system. It is suggested that an original geodetic base should be fixed as geodetic points of forced centering out of zone of virtual deformations. Deformation control benchmarks heights should be measured by trigonometric leveling. It is shown that RMS error in measuring the heights of points of geodetic monitoring network should not exceed 4mm. It is found that required accuracy in network building can be provided by III class leveling. To collect data about the depth of weak soils, located close to tunnel portals, as well as the borderlines of their sliding, it is for the first time suggested that surveys should be conducted using borehole inclinometer. The research proves that on pre-portal sites boreholes should be placed close to the group of deformation control benchmarks. © 2017 The Authors. Published by Elsevier Ltd. © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and (http://creativecommons.org/licenses/by-nc-nd/4.0/). Geoecology. Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and Geoecology Keywords: geodetic monitoring, transport tunnels.
Introduction Tunnels are considered to be the most complicated and highly-priced long-life transport engineering structures. According to [1] railway and motorway tunnels should be referred to I high level of structure responsibility, failures of which may lead to severe economic, social and environmental consequences. *
Tel.: +7-921-889-69-27. E-mail address:[email protected].
1877-7058 © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the International conference on Transportation Geotechnics and Geoecology
doi:10.1016/j.proeng.2017.05.066
418
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
Nowadays transport tunnel construction is, as a rule, attended by the need of organizing research-technical support of tunneling works. It is supposed to provide work safety by means of deformation monitoring, which is especially up-to-date in restrained urban conditions. While constructing and operating tunnels the following deformations should be considered: x Of a construction object itself; x Deformations of buildings and structures located in the area of an underground structure influence; x Deformations of retaining walls and adjoining soil mass In general, the term “deformation” means change in the shape of an observed object. In geodetic practice deformation is considered as change of an object location with relation to an original one. Modern geodetic surveys over structure control points displacements are performed establishing coordinates and heights of deformation benchmarks, fixed as tape reflectors or rotating prisms [2]. Structure control points change their location after the structure and are situated in places of possible deformation of a structure. In tunnels such places may be joints between cuts while concreting a tunnel lining, zones of carst cavities or harsh hydrogeological conditions, top of a tunnel arch part etc [3]. At the daylight surface such areas are expansion joints of portal structures, corners of buildings of surrounding development, property lines of soils having different strength properties etc. Deformation benchmarks together are geodetic deformation network, best reflecting behavior of deformation processes while constructing a tunnel. Depending on the kind of determined deformation, deformation benchmarks can be plan benchmarks, height benchmarks and plan-height benchmarks. Let’s analyze the stages of the proposed methods. While constructing a tunnel geodetic monitoring requires making a geodetic control network, points of which must be fixed securely. In each case it is necessary to make a preliminary calculation of the accuracy of deformation benchmarks and control network points location [4]. Tunnel structure displacements are supposed to be obtained with the use of high-accuracy total station and system of reflecting tapes, fixed on tunnel critical structures (piles, capping grillage, temporary supports, final tunnel lining). To determine the state of temporary supports and tunnel permanent lining we propose to measure tunnel contour displacements caused by rock pressure, hydrostatics and temperature action. Measuring transverse and horizontal distances between benchmarks by coordinate method, such kinds of deformation as compression, longitudinal and transverse displacement (Fig.1). After analyzing graphical and numerical results of measurements it is possible to estimate the state of tunnel structures.
Fig. 1 Location of deformation benchmarks on tunnel temporary supports С1, С2, С3, С4, СV – deformation benchmarks; L1-L6 – measured distances between deformation benchmarks.
419
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
Deformations in soil massive, cut by a tunnel, may be caused by not only mining works, but also landslide processes. That’s why within geodetic monitoring of daylight surface together with high-accuracy geodetic equipment it is efficient to use borehole inclinometers, giving necessary information of mass layer-by-layer movements in the area of tunnel mine allotment. The inclinometer – is an instrument which determines the inclination and direction of a drill-hole to control its spatial position [6]. An inclinometer usually consists of inclinometer sonde and data output device. Inclinometers are widely-used in gas and oil industry where they are used for borehole curving control. The result of inclinometric survey is information about soil slide boundary and values of horizontal displacements of rock formations. Boreholes are proposed to be placed evenly along the whole length of a tunnel. At near-entrance sites inclinometric borehole should be placed close to the group of deformation benchmarks (5-6 pcs.). After collecting field-survey information it is necessary to conduct a statistical analysis of the measured data [7]. At the first stage we propose to exclude rough mistakes using analysis for monotonicity of measurement series. At the second stage in order to determine the accuracy of measured values and directions it is efficient to use correlation analysis of inclinometric measurements results and measurements taken with total station. Examining correlation relationships between displacements G of deformation benchmarks and O of inclinometric borehole, positioned close to group of benchmarks, makes it possible to evaluate the reliability of measurements and draw a conclusion about the quality of field works [8,9]. Direct correlation shows that there are no rough mistakes in measurements, in correctness of choice of deformation benchmarks and inclinometric boreholes positioning. Positive coefficients of correlation rGO close to 1, not only confirm reliability in determining values and directions of displacements, but also provide the basis for forecasting [11,12]. As G variable we propose to take displacement value, obtained after tacheometric measurements (for each measurement cycle G 'x2 'y2 , where 'x , 'y – motions of reflective tape in x and y respectively in mm), as O variable – motions, taken by inclinometer sonde (mm). Pair coefficient of correlation can be calculated by: rGO
¦
n
i 1
¦
n
i 1
(G i G )(Oi O )
(G i G ) ( 2
¦
n
i 1
(Oi O )
,
(1)
2
where G i – results of measurements using total station; G – average in first sample; Oi – results of measurements using borehole inclinometer; O – average in second sample. Monitoring involves deformation behavior forecasting. To select a suitable forecast model we propose to take measurement results as time series with their following decomposition into components. As a rule, the simplest mathematical model, describing a time series, is a sum [13]: (2) X T M T ST YT , where M T – systematic component, describing the law of variation of process in time, trend; ST – regular composition oscillating about trend (seasonality); YT – random component. Trend reflects main tendency of variation of deformation dimensions in time. The most preferable practical method of selection of a suitable polynomial degree is the selection by the smallest sum of squared deviations of a theoretical curve from an empirical one. Herewith the following condition should be fulfilled: ( yi yi ) 2 o min , (3)
¦
where yi – values of time series, obtained during experiment, yi – theoretical values, obtained by calculation. Along with trend component a time series contains seasonal and random components [14]. While examining regular seasonal component in the context of tunnel deformation monitoring, it is clear that in order to develop this component part one should have observations of at least one-year period, because oscillation period is one year. This condition contradicts principal tasks of monitoring: to have a reliable picture of deformation process state at the time of tunneling and to have a possibility to make a reliable several stages forecast. Hence, it does not seem possible to find seasonal factor while analyzing tunnel deformations at the time of its construction. Furthermore, after distinguishing the trend time series decomposition comes down to the analysis of distribution law of series random component. If normalcy of distribution of residues is confirmed, one should make a forecast and
420
M.Y. Bryn et al. / Procedia Engineering 189 (2017) 417 – 420
assess it. Monitoring results are important to estimate tunneling dimensions (speed, tolerance for final lining lag) at the time of tunnel construction [15]. Consequently, forecast, based on monitoring results, should consider main tendencies of deformation processes and have a short-term lead period. Within these monitoring methods in order to make a short-term forecast of deformations we suggest using extrapolation of time series by tendency. Conclusions During construction an engineering company, consulting the results of geodetic monitoring, takes a decision if they should continue work within typical cross-section of a tunnel, confirmed by the project, or choose an another section under the influence of conditions of a real situation, which had not been found at the stage of engineering survey and because of that reason were not reflected in design documents. While tunneling in cohesive soils deformation processes go slowly, steadily and are characterized by constantly increasing size. Continuous analysis of temporal and spatial development of these processes makes it possible to optimize planning of actions which should be carried out in the area of bottom-hole front and in tunneling way itself to prevent a construction process from emergencies and to increase drilling speed.
References [1]. Construction codes and regulations «Motorway and railway tunnels». SNiP 32-04-97, p.6. М.: Gosstroy, 1997. [2]. Bezrodniy, K.P. An advanced underground imaging radar / K.P. Bezrodniy, V.B. Boltinzev, V.M. Efanov, V.N. Iljakhin, M.G. Tolstobrov / Proceedings of the World Tunnel Congress '99. –Norway, Oslo, 1999. – P. 31-34. [3]. Chapman, D. Introduction to tunnel construction / D. Chapman, N. Metje, A. Stärk / New York: Spon Press, 2010. – P. 417. [4]. Gairns, C. Development of a semi-automated system for structural monitoring using a reflectorless total station: thesis for the degree of master of science. Department of geodesy and geomatics engineering, University of New Brunswick, Canada 2008, 117 p. [5]. Kuang, S. L. Geodetic network analysis and optimal design: concepts and applications / S. L. Kuang. – Chelsea, Michigan: Ann Arbor Press, Inc., 1996. – 368 p. [6]. Schofield, W. Engineering surveying / W. Schofield, M. Breach / Oxford: Linacre House, 2007. – P. 367. [7]. Schäfer, T. Deformation measurement using terrestrial laser scanning at the hydropower station of Gabeikovo / T. Schäfer // INGEO 2004 and regional central and eastern european conference on engineering surveying, Bratislava, Slovakia, Novermber, 11-13, 2004. [8]. Schneider, D. Terrestrial laser scanning for area based deformation analysis of towers and water damns 3rd IAG / D. Schneider // 12th FIG Symposium, Baden, May 22-24, 2006. [9]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geodetic works for construction of the second stage of the Mariinsky theatre in St. Petersburg // Safety of train traffic: Proceedings of the 12th international conference. – Мoscow, 2011 P. 20-21. [10]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geodetic works for construction of the underground part of the second stage of the Mariinsky theatre in St. Petersburg // Proceedings of the Mining Institute. – St. Petersburg, 2012. Vol. 199. P. 329-333. [11]. D.А. Afonin, N.N. Bogomolova, M.Y. Bryn et al. Geoinformational monitoring for construction of the second stage of the Mariinsky theatre in St. Petersburg // The latest achievements in geodesy, geomatics and land development – European experience: Proceedings of the 8th international conference. – Chernigov, 2012. #8. P. 190-193. [12]. М. Kendall, А. Stewart Multivariate statistical analysis and time series, М. : Nauka, 1976. P. 506. [13]. G.А. Medvedev, V.А. Morozov Computer practicum on time series analysis [Electronic resourse]: Manual. Minsk.: «Electronic book BSU», 2003. P. 18.