The calculation formula that safeguarded the safet

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The calculation formula that guarded the safety of Shinkansen in the Japanese earthquake is...

the calculation formula that guarded the safety of Shinkansen in the earthquake is:

y = BT · e-at

there are 1200 damaged northeast Shinkansen in the East japan earthquake, and the whole line has been restored to operation at present. Although the track and equipment were seriously damaged, all vehicles in operation stopped safely. Although Japan suffered the largest earthquake in the history of Japan, Japan still maintained a record of zero casualties of passengers on Shinkansen. This is closely related to the calculation formula y=bt · e-at adopted after the derailment accident of the Shinkansen line in Shangyue caused by the Sino Vietnam earthquake in Niigata in 2004

the formula of the distance to the source can be calculated from the P-wave of initial inching

after the Hanshin · awaru earthquake in 1995, the Japan Railway Technology Comprehensive Research Institute conducted a joint study with the meteorological agency in order to support the early earthquake warning system "uredas" at that time. Uredas system can detect the initial microseism (P wave) of the earthquake, and send an alarm before the arrival of the main shock (S wave) to inform the train to brake in time. There are two points to be improved in this system, one is the algorithm of predicting magnitude by vibration, the other is the networking of seismograph

The algorithm of uredas is to observe P wave for 3 seconds and calculate the magnitude from the main period of P wave. This is because there is a correlation between P wave period and magnitude. However, when the earthquake is large, the damage of the fault lasts for more than ten seconds or even tens of seconds, so it can't be dealt with even if the shaking intensifies after only three seconds

Figure 1: in order to approximately calculate the amplitude of P wave, two coefficients (A and b) in the formula need to be determined

Figure 2: the formula consists of a straight line and an exponential function of attenuation. Coefficient B represents the longitudinal wave slope and coefficient a represents the duration. At first, technicians thought that a was more important, but later found that B was more important for predicting the distance and scale of the epicenter

technicians focused on the information of P wave for the first 1 ~ 2 seconds to predict the situation after that, and explored whether there was a calculation formula that could be roughly applicable to the amplitude change (Fig. 1), but could not find it. a: The measuring range of the experimental force is wider, more accurate and more stable: due to the zero covering problem of the electro-hydraulic servo control valve in the static control (this is the inherent characteristic of the electro-hydraulic servo valve itself), coupled with the sealing and friction problems of the oil cylinder, the output (displacement and actual force) near the zero position is not linear, and it is easy to crawl at low speed, with poor stability, and the initial pressure is high when preparing to give up, A technician of the railway comprehensive research institute came up with a simple method, which is to "combine the straight line of longitudinal wave with the attenuation exponential function" (Fig. 2). There is a close relationship between the longitudinal wave slope and the epicenter distance (Fig. 3)

Figure 3: in about 300 examples, the b value is inversely proportional to the epicenter distance. In other words, if B can be determined, the epicenter distance can be determined. Because the epicenter distance, amplitude and magnitude are interrelated, the magnitude can be calculated according to the amplitude

if the epicenter distance can be measured first, the magnitude can be calculated and updated at any time while observing the amplitude. Since the slope is limited within a certain range, the interference of the anti dry hydraulic universal testing machine designed and manufactured according to the specifications can also be improved by calculating the abnormal value

Figure 4: seismograph set in substations along the railway. In case of power failure, the inverted pendulum mechanical vibration detection device (lower right shell) used since the opening of Tokaido Shinkansen is still being used

3. After the derailment accident of Shinkansen in Shangyue, JR East Japan added seismometers along the Shinkansen in 2005 while improving the system, so that the average interval of the original seismometers was reduced from 20km to 13km according to the actual measurement of 100mm (Figure 4). And connect the seismograph. When the seismograph close to the epicenter detects P wave and judges that the earthquake has a great impact, it will notify the adjacent seismograph. That is to say, it can alarm before P wave *

* the seismograph is installed in the substation along the Shinkansen line, and the power transmission will be stopped in case of an earthquake. When the train detects power failure, it will automatically use air pressure to make emergency braking. In addition to the substation, the Northeast Shinkansen has also installed seismometers on the Pacific coast beyond the track, which have existed since 2005

the reason why Shinkansen did not have passenger fatalities was not only due to its strong technical strength, but also benefited from good luck. However, with the continuous development of technology, the proportion of relying on luck will certainly be lower and lower. (: Kentaro musaki)

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