岷江上游“7·10”泥石流对公路的危害方式及成因

Hazard Characteristics and Causes of “7·10 ” Debris Flow along Highways in the Upper Reaches of Minjiang River

2013-07-10,岷江上游暴发大型群发性泥石流灾害,泥石流以淘刷、冲击、淤塞、压顶、磨蚀等方式对地震灾区公路直接造成严重破坏,其引发的溃决洪水、河床上升增大受灾范围,加重了灾害损失。分析了泥石流对道路工程的成灾方式:对桥梁工程破坏包括淤塞、淘蚀基础、冲毁等;对路面路基工程破坏包括淤埋、淘刷路基、冲毁等;对隧道工程破坏包括堵塞隧道洞口,破坏洞口墙体并引起衬砌支护结构破坏,损毁隧道内附属设施等;对明洞、棚洞工程破坏包括堵塞洞口、冲毁洞口结构,磨蚀洞顶,压顶并引起衬砌支护结构破坏,损毁排水、通风、电力附属设施等。分析了泥石流造成道路严重损失的原因,其中,公路工程选址不当、风险估计不足,桥涵过流净空不足,泥石流防灾措施不完善,泥石流的严重冲刷、冲击作用是主要原因。针对泥石流危害公路的特征和地震区泥石流防治中存在问题,提出了地震山区公路在灾后重建与道路规划中的减灾措施。

On July 10, 2013, debris flows with large-scale simultaneously occurred and directly caused serious damages for highways in the upper reaches of Minjiang River. That debris flow deposited riverbed and induced dambreaking flood increases the affected range and aggravated the loss of highways. This article analyzed the debrisflow damage modes to highway engineering, including： 1 ） depositing bridge clearance, scouring bridge foundation and directly destroying bridges ; 2） burying pavement and subgrade, scouring subgrade, and washing out roads; 3 ） blocking tunnel entrance, destroying tunnel lining structure of the cave wall at tunnel entrance, damage to tunnel＇ s ancillary facilities; 4） blocking the mouth of open tunnel or shed tunnel engineering, impacting tunnel entrance structure of, destroying drainage, ventilation and power ancillary facilities of open tunnel or shed tunnel engineering. Furthermore, according to field observation, a preliminary analysis was used to discuss the causes of serious losses of highways in the upper reaches of Minjiang River. And the major causes induced the improper location and insufficient risk estimates for highway engineering, insufficient clearance of bridge and culvert, an uncompetitive system of debris flow disaster prevention and mitigation, and serious scouring and impacting capability of debris flow. Through analyzing the hazard characteristics of debris flows along highway and the problems of debris flow prevention and control, this study proposed countermeasures for disaster mitigation in post-disaster reconstruction and highway planning.