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2013-07-10四川省汶川县岷江干流沿线群发性泥石流(简称“7·10”泥石流)对都(江堰)汶(川)公路(G213线)和都汶高速桥梁、路基、隧道造成重大破坏,G213线和都汶高速共16处中断,尤以G213线破坏严重。苏坡店沟毛家湾大桥是“7·10”泥石流冲毁桥梁、造成交通中断的典型模式。在野外调查、采样和数据分析的基础上,确定苏坡店“7·10”泥石流的重度18.5 k N/m2,流速9.3 m/s,峰值流量232.5 m3/s,剪应力13.3 k Pa。高速、大流量泥石流沿陡峻的主沟排泄过程中,强烈侵蚀和起动沟床,左侧桥基基础强烈淘蚀悬空,形成1.65 m宽的临空面;在泥石流的作用下,桥基沿主沟发生5 m位移变形,导致桥梁垮塌,交通中断。经计算,桥墩下部土体支撑面积为42.8 m2,基底最大压力达545 k Pa,大于规范规定允许承载力,并且从抗倾覆角度计算也超出了规范要求,处于失稳状态。针对跨越高陡泥石流沟的桥梁,建议加强泥石流沟排导、预设足够的桥下净空高度、增加桥梁防护等措施来减少桥梁的破坏。
2013-07-10 Massive debris flows along the Minjiang River in Wenchuan County, Sichuan Province (abbreviated as “7.10” debris flow) affect both the Wen-Chuan Highway (G213 line) and the Du-Wen high-speed bridges, subgrade and tunnels Causing significant damage. The G213 line and Duong Van Expressway had a total of 16 disruptions, especially the G213 line. Supo shop ditch Maojia Bay Bridge is “7.10 ” debris flow destroyed the bridge, resulting in a typical mode of traffic disruption. On the basis of field investigation, sampling and data analysis, the severe 18.5 kN / m2 debris flow in Supo shop was determined, the flow rate was 9.3 m / s, the peak flow was 232.5 m3 / s and the shear stress was 13.3 kPa . During the discharge of high-velocity and large-flow debris flow along the steep main channel, the trench bed is strongly eroded and started. The foundation of the left abutment foundation is strongly scavenging and vacant to form a 1.65 m wide free surface. Under the action of debris flow, Ditch 5 m displacement deformation, resulting in the collapse of the bridge, traffic interruption. After calculation, the supporting area of the soil beneath the piers is 42.8 m2, and the maximum pressure of the foundation reaches 545 kPa, which is larger than the allowable bearing capacity of the code, and the calculation from the anti-overturning angle also exceeds the specifications and is in an unstable state. Aiming at the bridge spanning the high and steep debris flow ditch, it is suggested to reduce the damage caused by the bridge by strengthening the draining guide of debris flows, presetting sufficient headroom under the bridge and increasing the protection of bridges.