Damage to Highway Tunnels Caused by the Wenchuan Earthquake
(1 School of Civil Engineering, Fujian University of Technology, Fuzhou 350108; 2 Key University Laboratory of Underground Engineering, Fujian Province, Fuzhou 350118)
Abstract：
Quantitative indicators and a classification system of seismic damages to highway tunnels were developed based on a study of the seismic damage rules for highway tunnels in the Wenchuan seismic area. The results show that: the proportion of tunnel lining crack length is the highest along the total length of tunnel, and the length of secondary lining collapse and inverted arch dislocation goes the second; the proportion of most types of damage in surrounding rock of grade V is higher than that in surrounding rocks of other grades; in the area with Ⅹ & Ⅺ seismic intensities, damage at the fault section is the worst, and the damage at the portal section comes the second; the seismic damage severity decays quickly with increased distance from the epicenter, and the tunnels most seriously damaged are mostly located less than 10 km away from the epicenter, and nearly two-thirds of them are within 20 km;the degree of seismic damage to the tunnel in hard rock decreases with an increase of buried depth, and the relation? ship between the degree of damage and buried depth is unclear regarding tunnels in soft rock; the actual seismic intensities are higher than the fortification intensities specified for the tunnels with serious damage, and as for tunnels with moderate damage, nearly two-thirds of them have higher seismic intensities than the designed ones; seismic damage is serious when the crossing angle between the tunnel axis and the seismogenic fault is 60°~90°, and it is relatively light under angles of 30°~60°; and the primary support and secondary lining can′t work cooperatively during an earthquake because of the waterproof membrane, which increases the risk of seismic damage.
2017, Vol. 54 