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| 4. |
- Bahrekazemi, Mehdi, et al.
(author)
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The role of earthquake warning systems
- 2018
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In: ISRM International Symposium 2000, IS 2000. - : International Society for Rock Mechanics.
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Conference paper (peer-reviewed)abstract
- The fact that each year thousands of people in seismically active parts of the world are killed or injured due to major earthquakes urges for continuous efforts in order to lessen the size of the catastrophe. Technical achievements made in recent years have made it possible to install an Earthquake Warning System (EWS) that can issue alarm a few seconds before the damaging waves reach the area. The main idea behind such systems is to make use of the difference between the propagation velocity of S-waves, and radio waves to issue earthquake alarm before arrival of the destructive part of the seismic waves. As the efficiency of an EWS depends on many factors, each area must particularly be studied in order to determine if such a system would be appropriate or not. In this paper EWS has been studied as a complementary measure against earthquake in Iran a country with more than 100,000 casualties due to earthquakes in recent decades. A simplified method has also been suggested for comparing the costs of the project with the economical advantages of it. Using the suggested method it has been shown that an EWS would be both economical and efficient in some parts of the country.
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| 6. |
- Bodare, Anders
(author)
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Markvibrationer från järnvägstrafik
- 2006
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In: Bygg och Teknik. - : Förlags AB Bygg & teknik. - 0281-658X .- 2002-8350. ; :2, s. 47-52
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Journal article (pop. science, debate, etc.)abstract
- Problem med markvibrationer från järnvägstrafik har funnits sedan järnvägar först togs i bruk. Redan Lord Rayleigh deltog i en kommission som studerade både mark- byggnadsvibrationer i London i början av nittonhundratalet. De senaste tre decennierna sett ett ökat intresse, i hela Europa, för järnvägens vibrationsproblem, en ökning som fortsätter allt snabbare. Stora projekt pågår för närvarande i England, Holland, Frankrike, Tyskland och i viss mån också USA, Italien och Tjeckien, förutom också i de Nordiska länderna, Norge, Finland, Danmark och Sverige. Just nu pågår andra fasen av ett internordiskt projekt kallat NordVib.
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| 7. |
- Bodare, Anders, et al.
(author)
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Planning and Execution of Rock Blasting in Urban Areas
- 2009
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In: Environmental Vibrations. - 9787030257659 ; , s. 784-789
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Conference paper (peer-reviewed)abstract
- Proper management of technical risks during blasting facilitates efficient project management and helps keeping costs and safety at an acceptable level. it is of crucial importance to incorporate the process of risk management in the design and execution of the project. Risk analyses of the environmental effect of blast-induced vibrations are, in many cases, based on crude concepts which do not take into consideration the fundamental nature of vibratory motion. Realistic modeling of wave propagation in soil and rock requires that correct dynamic parameters are considered and appropriate attenuation models are applied. It is possible to apply relatively simple vibration attenuation concepts for prediction of vibrations in soil and rock and their interaction with structures on or below the ground surface.
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| 8. |
- Bodare, Anders, et al.
(author)
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Sub and super seismic train induced ground vibrations-theoretical considerations and test results
- 2005
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In: Environmental Vibrations. - 0415390354 ; , s. 3-10
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Conference paper (peer-reviewed)abstract
- With the introduction of high speed trains in Sweden, high vibration levels were encountered in low embankments founded on soft, cohesive soils. In these cases, it appeared that the maximum amplification occurred when the train speed exceeded a critical value. A series of field tests were therefore carried out at Ledsgard, a site in south western Sweden near Gothenburg, in order to investigate the problem. In these tests, an X2000 high speed train was run at speeds ranging from 10 km/h to 200 km/hr, and a substantial increase of the peak values of the particle displacement and velocity was observed at train speeds of 140-160 km/hr. The shear-wave velocities varied between 40 m/s to 60 m/s in the upper layers of the soil, which means that the tests at higher train speeds were performed with super seismic speeds in relation to the shear wave velocity of the soil. This paper presents theoretical considerations on ground motions in the track environment when a train runs at sub and super seismic speeds. Mathematical expressions are presented along with a conceptual model that illustrates the behaviour. The phenomenon of the "two sources" for super seismic train speeds is explained and displacement and velocity time histories from the model are discussed for various speeds. Recordings from the field measurements are also presented and compared with the results of the conceptual model.
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| 10. |
- Costa, Pedro Alves, et al.
(author)
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Influence of soil non-linearity on the dynamic response of high-speed railway tracks
- 2010
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 30:4, s. 221-235
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Journal article (peer-reviewed)abstract
- The main objectives of this paper are the evaluation of the relevance of the non-linear behaviour of the soil on the track response and the validation of a methodology, which includes these effects through an equivalent linear analysis. The proposed numerical model is based on 2.5D finite/infinite elements method, coupled with an iterative procedure in order to obtain an agreement between the strain levels and the dynamicproperties of the materials. In order to validate the model, the case study of Ledsgard was simulated, and the experimental and numerical results of displacements of the trackwere compared, considering several circulation speeds for the X2000 train. From the results, it is possible to recognize that the stiffness degradation, function of the strain level, plays a relevant role for the case of high-speed railway lines on soft ground. Moreover, the simulations developed with the proposed methodology provided similar results to those observed, independently of the train speed, contrary to what was obtained when the elastic linear model was used.
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| 11. |
- Malmgren, Lars, et al.
(author)
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The excavation disturbed zone (EDZ) at Kiirunavaara mine, Sweden - by seismic measurements
- 2007
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In: Journal of Applied Geophysics. - : Elsevier BV. - 0926-9851 .- 1879-1859. ; 61:1, s. 1-15
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Journal article (peer-reviewed)abstract
- The presence of an excavation disturbed zone (EDZ) around an excavation boundary can significantly affect the overall performance of the excavation and the general safety of men and equipment. Hence, it has been an important subject of research in various rock excavation projects. The EDZ is generally defined as the rock zone beyond the excavation boundary where the physical, mechanical and hydraulic properties of the rock have been significantly affected due to the excavation and redistribution of stresses. For LKAB's Kiirunavaara underground iron ore mine in Sweden, the understanding of the EDZ is essential for optimal design of rock support. With this main objective an EDZ investigation was conducted at the mine using seismic measurement techniques. Cross-hole seismics and spectral analyses of surfaces waves (SASW) were the main techniques used. Borehole Image Processing Systems (BIDS) complemented the seismic measurements. The results show that an EDZ with a thickness of 0.5-1.0 m existed behind the boundaries of the mining drifts being investigated. The magnitude of the Young's modulus of this zone was 50% to 90% of that of the undisturbed rock.
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| 12. |
- Wersäll, Carl, et al.
(author)
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Dynamic response of vertically oscillating foundations at large strain
- 2014
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In: Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014. - : CRC Press. - 9781138001480 ; , s. 643-647
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Conference paper (peer-reviewed)abstract
- A method for calculating the dynamic response of a vertically oscillating foundation on soil with strain-dependent properties is developed. Strain-dependent stiffness and damping are incorporated by an iterative procedure, presenting the response in frequency domain. The calculated dynamic displacement amplitudes are compared to small-scale tests using a vertically oscillating plate. The calculated dynamic quantities agree well with measured amplitudes over a wide frequency range.
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| 13. |
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| 14. |
- Wersäll, Carl, et al.
(author)
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Planning and Execution of Rock Blasting Adjacent to Tunnels
- 2009
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In: Environmental Vibrations. - 9787030257659 ; , s. 749-756
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Conference paper (peer-reviewed)abstract
- Prediction and monitoring of vibrations from rock blasting is of practical importance. Damage to rock tunnels caused by blasting is fundamentally different to that of conventional buildings. Different damage mechanisms are discussed as well as methods to monitor the development of cracks by analysis of frequency content. For the assessment of the damage potential it is essential to understand wave propagation in rock and the dynamic response of cavities to vibration excitation. Vibration frequency and wavelength in relation to the size of the cavity are important parameters. Vibration amplification of a circular tunnel to a plane wave is analyzed and guidelines given for practical design applications. Filtering the vibration signal, which is often required in national standards, car. give misleading results for tunnels in rock.
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| 15. |
- Wersäll, Carl, et al.
(author)
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Vibration Source Localization along Railway Tracks
- 2012
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In: Noise and Vibration Mitigation for Rail Transportation Systems. - Berlin : Springer. - 9784431539261 ; , s. 267-274
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Book chapter (peer-reviewed)abstract
- Ground-borne vibration from railway traffic is an increasing problem in urbanized areas and measures are often needed to minimize its effects on the environment. An important question when dealing with railway problems is to identify the source(s) of vibration emitted along the railway track. Once this information is available, it is often possible to mitigate the problem by improving stiffness of the railway track and/or to upgrade worn-out or damaged rail sections and turnouts. This paper describes a method which makes it possible to determine the locations of track sections which are likely to emit strong ground vibration. A purpose-built track-bound vehicle which can be vibrated continuously at different frequencies can identify track sections having unfavorable dynamic foundation conditions. A theoretical concept is proposed to calculate the potential of energy emission from the vehicle moving along the track. Further, an innovative method is presented which makes it possible to determine the location of vibration sources by measurement of ground vibrations from existing railway traffic. This information can be used to determine the location of track sections where remedial measures are needed. Results are presented, illustrating application of the concepts, which can also be applied to other types of vibration problems.
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| 16. |
- With, Christoffer, et al.
(author)
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Deriving parameters of track and subsoil with a stiffness measurement vehicle
- 2007
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In: Proceedings Of The 3rd International Symposium On Environment Vibrations. - 9789860118506 ; , s. 474-479
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Conference paper (peer-reviewed)abstract
- High speed trains and heavy loaded freight trains can induce strong shaking in track and ground in vicinity of a railway line. Excessive vibration levels in embankment and ground could give rise to serious problems. increasing speed and axle load is causing a growing concern for the authorities. In Sweden, a special measuring car, RSMV, has been developed to investigate the condition of the tracks. The aspect that recently has been put under investigation is if, by simultaneous measurements of an applied force to an axle and its acceleration response, the point flexibility of the track system, can be modeled by a BEK-system. This paper describes the method of derivation of parameters and present results from one site.
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| 17. |
- With, Christoffer, et al.
(author)
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Evaluation of track stiffness with a vibrator for prediction of train-induced displacement on railway embankments
- 2009
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 29:8, s. 1187-1197
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Journal article (peer-reviewed)abstract
- A measuring car, the rolling stiffness measuring vehicle (RSMV), has been developed to investigate track conditions. The investigation described in this paper firstly attempts to understand whether the point flexibility of the track, i.e., the track-embankment-subsoil system, can be obtained by simultaneously measuring the force applied to an axle of the measuring car and the resulting acceleration response. Secondly, it attempts to determine the physical properties of the track by modelling it as a Bernoulli-Euler beam oil a Kelvin foundation. The final part of the paper investigates the possibility of predicting displacements on a railway embankment based oil the physical properties obtained after a train passage. Results from two sites in Sweden, Kumla and Kåhög, have been used. Investigations give encouraging results. However, as seen here, it can be difficult to analyse and obtain parameters if the resonance frequency of the system is low. The peak particle displacement of the ballast on the railway embankment was achieved with fair accuracy for both Kumla and Kåhög using the results from the accelerometer on the RSMV.
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| 18. |
- With, Christoffer, et al.
(author)
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Field test of a semi-empirical model for prediction of train-induced ground vibration
- 2005
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In: Environmental Vibrations. - 0415390354 ; , s. 351-355
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Conference paper (peer-reviewed)abstract
- This paper presents a field test of the semi-empirical model ENVIB-01 in predicting train-induced ground vibrations. The model is meant to be used in an early design phase when the major concern is to locate areas with heightening risk of excessive ground motion or before allowing operators to increase speed and/or load. ENVIB-01 is easy to use and can quickly produce prediction of ground motion at the railway embankment and in the vicinity of the track. Measurements at one site are here presented and the results from the embankment and at distances of up to 30 m from the track are compared to a prediction achieved with the model.
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| 19. |
- With, Christoffer, et al.
(author)
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Identification of effective properties of the railway substructure in the low-frequency range using a heavy oscillating unit on the track
- 2010
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In: Archive of applied mechanics (1991). - : Springer Science and Business Media LLC. - 0939-1533 .- 1432-0681. ; 80:9, s. 959-968
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Journal article (peer-reviewed)abstract
- As the demand for predictions of train-induced vibrations is increasing, it is essential that adequate parameters of the railway structure are given as input in the predictions. Gathering this information can be quite time-consuming and costly, especially when predictions are required for the low-frequency emission. This article presents a procedure for deriving the effective properties of the foundation under the sleepers of a railway track from measurements taken with a heavy oscillating unit on the track. The unit consists of two masses inside a modified freight car that exert a dynamic force in the range 3-30 Hz on one of the two axles. The ratio of force applied on the axle over the resulting response measured with an accelerometer is studied. The foundation of the sleepers is modelled using a frequency-dependent complex-valued dynamic stiffness.
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| 22. |
- With, Christoffer, et al.
(author)
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Prediction of train-induced vibrations inside buildings using transfer functions
- 2007
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 27:2, s. 93-98
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Journal article (peer-reviewed)abstract
- This article presents a study of the use of transfer functions to predict vibrations inside a building due to train-induced ground vibrations. It is proposed that knowing the transfer function of a building, the vibrations inside a similar building can be predicted given a known ground motion outside. A comparison has been conducted between predicted and measured vibrations inside a building in south-western Sweden due to freight and passenger trains. The transfer function was derived by using a stationary vibrating source. The average particle velocity (1 s-r.m.s.) inside the house was calculated with the transfer functions with an average error of -10%, -0.02mm/s. Prediction was achieved with a standard deviation of 23%, 0.06mm/s when no filtering of the data was used. Further work is needed to ascertain the accuracy of this method.
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| 23. |
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| 24. |
- With, Christoffer, et al.
(author)
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Validation of an empirical model for prediction of train-induced ground vibrations
- 2006
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 26, s. 983-990
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Journal article (peer-reviewed)abstract
- This paper presents a validation of EnVib-01, an empirical model to predict train-induced ground vibrations in a preliminary design phase. The model is simple to use and gives a quick assessment of the magnitude and the distribution of the ground motion that can be expected in the vicinity of the track. It can be of use during planning of a new track or before allowing trains to run faster with heavier cargo on an existing railway line. The model has been validated from two field measurements in Sweden. The strengths and weaknesses of the model, which has shown promising results, are discussed.
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| 25. |
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| 26. |
- With, Christoffer, et al.
(author)
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Wave barrier of lime-cement columns against train-induced ground-borne vibrations
- 2009
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 29:6, s. 1027-1033
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Journal article (peer-reviewed)abstract
- This paper presents a comparison between measured train-induced ground vibrations in the free-field before and after countermeasures had been taken at Kahog near Gothenburg in Sweden. A wave barrier of lime-cement columns was constructed parallel to the railway in order to reduce the ground-borne vibrations inside nearby buildings. On top of the barrier an embankment was built to reduce air-borne vibrations. Due to the wave barrier design, part of the energy content of the waves was expected to be reflected by the screen and transmitted energy was expected to be partly scattered. Contribution from the noise-embankment was not thought likely but could not be ruled out due to its fairly large mass and its close proximity to the railway. The effect of the mitigating measures resulted in a 67% reduction of the maximum particle velocity at 30 m and 41% at 60 m from the railway. A simple two-dimensional finite element model has been used to Study the relative importance of the wave barrier and the noise-embankment as contributors to the mitigation recorded of the ground vibrations in the field. It is concluded with respect to ground vibrations that both the barrier and the embankment had a mitigating effect but that the contribution from the barrier dominated. Furthermore, it is seen from the field results as well as the Simulation that the effect of the mitigating action is reduced with increasing distance from the railway.
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