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5.12地震不仅直接引发了大量的崩塌、滑坡,而且降低流域内岩土体的强度,使其更易于受到侵蚀,从而为泥石流的形成提供丰富的固体物质。灾区震后泥石流活动频繁,并造成了较大的损失。泥石流沟的危险度评价是进行灾后重建的必要条件。选择震后固体物质增加量、地震烈度和堰塞坝规模这3个重要参数,提出了基于泥石流设计流量的震后泥石流危险度增加系数的评价方法。该方法通过计算地震后新增加的固体物质方量与通过配方法计算出的一次泥石流冲出物总量的比值,该比值与地震烈度影响系数的乘积及堰塞体蓄水量以流域50年一遇的流量排泄所需要时间3项之和来表达地震后泥石流危险度增加量。经灾区9条典型泥石流沟谷的计算验证,该方法做为一种新的方法,可快速、准确地评价5.12地震后灾区泥石流危险度的增加情况。
The 5.12 earthquake not only triggered a large number of landslides and landslides directly, but also reduced the strength of rock and soil mass in the river basin, making it more susceptible to erosion and providing abundant solid material for debris flow formation. Debris flow after the earthquake strikes frequent and caused greater losses. The risk assessment of debris flow ditches is a necessary condition for post-disaster reconstruction. After selecting the three important parameters of the increase of solid matter, the seismic intensity and the size of damped dam after the earthquake, an evaluation method based on the design flow rate of debris flow to increase the risk of debris flow hazard was proposed. The method calculates the ratio of the amount of newly added solid matter after an earthquake to the total amount of debris outflows calculated by the method of formula and the product of the ratio and the seismic intensity influence coefficient and the water volume of the dam body for 50 years The sum of the three times of traffic excretion in one event expresses the increase of the risk of debris flow after the earthquake. Through the verification of nine typical debris flow valleys in the disaster area, the method is a new method to evaluate the increase of the risk of debris flow in the disaster area after the 5.12 earthquake quickly and accurately.