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- Bahrekazemi, Mehdi, et al.
(författare)
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The role of earthquake warning systems
- 2018
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Ingår i: ISRM International Symposium 2000, IS 2000. - : International Society for Rock Mechanics.
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Konferensbidrag (refereegranskat)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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- Bahrekazemi, Mehdi, 1966-
(författare)
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Train-Induced Ground Vibration and Its Prediction
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis based on a series of ground vibrationmeasurements at different sites presents two differentsemi-empirical models for prediction of ground-borne vibrationdue to train traffic. Ground-borne vibration due to train traffic may causeannoyance to people who live nearby the track or interfere withthe operation of sensitive equipment inside the buildings.Therefore despite the fact that ground-borne vibration fromtrain traffic usually do not cause damage to the buildings, theeconomical and environmental aspects of the issue justifycareful assessment of the problem prior to constructing newrailway tracks or upgrading the existing ones for heavier andfaster traffic. It is in this context that a model forprediction of traininduced ground-borne vibration can beuseful. Any model for prediction of ground-borne vibration due totrain traffic must include at least three main components.These three main components, which themselves may include manydifferent parts are the source, propagation path, and thereceiver. Depending on how detailed these three components aredefined, and how accurate the predictions made by the modelare, they can be classified into three different classes, classI, class II, and class III. The first model presented in the thesis is a class Iprediction model that can be integrated into a GIS system inorder to study large areas and thereby choose the best positionof a new railway or determine locations with risk for excessiveground-borne vibration in case of upgrading existing railwaysfor higher axle load and train speed. A class II semi-empirical model is also suggested in thethesis which can be used in order to study the problem in amore accurate way and rather short time at those locations thathave been identified by the first model. This model is based ona library of sub-models corresponding to the source, path andthe receiver. The sub-models can be put together by the user inorder to make a specially made confectionary model suitable foreach specific site and case. Using the measurement data some general conclusions havealso been discussed with respect to the effect of wheel force,train speed, train type, train length, geotechnical conditionsof the site, building’s dynamic characteristics, and somemitigation methods on the ground-borne vibration induced bytrain traffic. Key words:ground vibration, train traffic, predictionmodel, vibration effects, vibration mitigation.
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- With, Christoffer, et al.
(författare)
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Validation of an empirical model for prediction of train-induced ground vibrations
- 2006
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 26, s. 983-990
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Tidskriftsartikel (refereegranskat)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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- With, Christoffer, et al.
(författare)
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Wave barrier of lime-cement columns against train-induced ground-borne vibrations
- 2009
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 29:6, s. 1027-1033
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Tidskriftsartikel (refereegranskat)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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