地震区公路隧道洞口山洪泥石流受灾分析及启示

Analysis of a Flash-Flood Induced Debris Flow at a Highway Tunnel Portal in a Seismic Region

高烈度地震特重灾区隧道如何抵御泥石流等次生灾害是震区隧道工程设计、施工的重要问题。文章通过对映秀至汶川高速公路隧道洞口在"7.9"山洪泥石流中损害情况进行的实地调查和系统分析,认为"5.12"震后造成的山体松动损伤、明洞回填材料刚度和厚度不足,以及隧道明洞段地基抗冲刷能力不够是隧道洞口受损的主要原因,由此提出了相应的设计思路:强化震后(潜在)灾害评估,建立超预期设计理念;重视隧道明洞回填质量和效果;借鉴桥式基础,预留泥石流途经通道,可以起到防灾减灾和减少国家财产损失的作用。

Resisting secondary disasters like a debris flow is critical during the design and construction of tun- nels in regions with high seismic intensity. Based on the field survey and system analysis of the flash-flood in- duced portal damage to the Yingxiu-Wenchuan highway tunnel on July 9th, 2013, this paper concludes mountain loosening by the Wenchuan earthquake, stiffness and thickness insufficiencies of the backfilling material, and poor anti-erosion of the foundation in the cut-and-cover section of the tunnel are the main reasons for portal damage. It also puts forward relevant design ideas which can prevent and reduce disasters and minimize state asset losses, such as strengthening the evaluation for post-seismic potential hazards, designing beyond expectation, emphasizing quality and effectiveness of backfilling, and providing bridge-type channels for potential debris flOWS.