| Highway functions as the junction of the East and the West in terms of the regional economic structure of China. The"5.12" earthquake in wen’chuan has caused tremendous damages to the highways; however, it also provided a valuable opportunity for Chinese seismic researchers to study and improve the technology of seismic highway engineering of China. In order to reveal the mechanism and the law of highway when it has been damaged by earthquakes and to discover the study of the vulnerability of highways respond to earthquakes, we has finished following researches for the paper:We have been sent to the field with researchers after the earthquake to investigate the damages; it has taken us about three months to collect survey data of the damaged Subgrades in more than1,400spots; also, we have taken more than10,000photographs there. We have collected several design data of the classic highways such as G213road (Dujiangyan-Yingxiu) in the wen’chuan earthquake, which provides basis for the coming research.Investigation and statistical results indicate that the mostly damaged embankment distribute in9to11intensity area. When the road’s trend parallel to the fault, the embankment will probably damaged when earthquake happen. The gravity retaining wall had a large number of damage, almost on the soil foundation, especially grouting wall. Flexible retaining structure has the better seismic performance compare with the gravity retaining wall. The main failure types of gravity retaining walls include collapse, deformation and cracks on surfaces, overturning. Compare with filling wall the cutting wall has more complicated failure types and damage number, semi-filling and semi-excavating subgrades damaged more, mostly located in hillside. Subgrades on soil damaged more serious. The main failure types of subgrades include sink and crack, buried by the landslide also seriously. Rock slope happened more damage. Landslides have the highest occurrences and damage rate in the event of the earthquake. Grade of damaged side slope focus on over35°. Proper slop protection is necessary to reduce the damage when the earthquake happens.Based on the investigation data of damages to the highway subgrade from Wenchuan earthquake, we have established some systemically statistical seismic vulnerability models of highway embankment. Depends on the measured record in wenchuan earthquake, we have modified the motion attenuation model, and have estimated the PGA of where the destroyed embankment were locating. Under the condition that the PGA of damaged spots has been known, we can estimate seismic vulnerability models by making the logarithm distribution function of two-parameter reliability as the seismic fragility function. In the end, we taken the lkm road section of the G213road (Dujiangyan-Yingxiu) as a example, then estimated the damage of embankment which was caused by Wenchuan earthquake.To establish the matrix fragility curves is simple and convenient, even though people cannot directly serve it as damaged ratio for establishing, but from the perspective of vulnerability, it has revealed the general law and tendency of semetic damages of embankment including subgrade, retaining wall and slope, in Wenchuan earthquake.The vulnerability model of subgrade which adopt the double parameters logarithmic normal distribution functions can not only estimate the damaged ratio of embankment under seism actions, but also calculate economic loss quickly and continently from the damages of embankement. Continually improving estimating ways can not only offer the government some effective helps to make wisely emergency decisions after earthquakes, but also helps relevant departments for dealing with serious damaged sections rapidly. |
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