干热河谷区泥石流活动特征及对交通干线的危害——以峨汉高速为例

摘要

干热河谷区泥石流活动可能性高,对重大交通干线沿线工程存在严重的威胁.根据野外调查,结合遥感解译,采用泥石流运动参数常用计算方法,探讨了峨汉高速段泥石流的活动特性,以及泥石流对峨汉高速的危害及防治模式.研究显示:① 峨汉高速所在的干热河谷区地形条件复杂,高差大,满足泥石流形成的势能条件;降雨集中且丰富,干热条件加剧了泥石流的形成;该段娃娃沟、板洋沟、大旋沟三条沟物源总量分别为690.98万,160.39万,150.19万m3,有效动储量分别为131.63万,31.48万,22.02万m3,为泥石流的形成提供了丰富的松散堆积物质.② 区域泥石流流速快,3条沟最大流速达5.85 m/s;流量较大,最大为娃娃沟,其100 a一遇、50 a一遇泥石流峰值流量分别为545.64,401.52 m3/s;泥石流大石块冲击力大,最大达到1797.01 kN.③ 区域泥石流对峨汉高速的危害表现为泥石流对桥墩的冲刷、掏蚀及大石块撞击的危害;其防治措施为加宽桥梁桥墩跨沟宽度、修筑排导工程、进行坡面及柱面防护.%The debris flow activity is highly possible in dry-hot valley area, which poses a potential threat to major traffic trunk line project. Based on field investigation and remote sensing interpretation,this paper discusses the characteristics of debris flow activities in the E-Han highway section and the hazards of debris flow to the highway and the prevention and control model using debris flow parameters calculated by the commonly used methods. The results show that: ① The dry-hot valley area, where the E-Han highway located,has complex topographic conditions and great elevation difference,which are potential energy conditions for debris flowing. In the time and space,the rainfall is concentrated and rich,and the dry heat condition intensifies the formation of debris flow;the total material sources in Wawa gully,Banyang gully and Daxuan gully are 690.98×104,160.39 ×104,150.19×104m3,the effective dynamic reserves are 131.63×104,31.48×104,22.02×104m3, respectively, which provide abundant loose accumulative material for the debris flow formation. ② The debris flow velocity in the region is fast,the maximum flow velocity of the three gullies is 5.85 m/s. The debris flow discharge is large,among 3 gullies,Wawa gully is the largest and its debris flow discharges of 100-year return period and 50-years return period are 545.64,401.52 m3/s,respec-tively. The impact force of large rock in debris flow is great,maximum reaching 1797.01kN. ③The hazards of the debris flow to the E-Han highway is the pier scouring,erosion by debris flow and pier collision by big stones. The prevention measures are as follows:widening bridge pier span,constructing training and releasing project,protecting the slope and pier column.