有限防淹条件下的山洪沟防洪治理

Flood management countermeasures of mountain creeks with limited protection

受山洪沟流域面积小、影响人口较少情况的制约,在现行规范条件下,山洪沟防洪治理不可能采取较高的防洪标准,一般多为10年一遇,建筑物等级为5级。但是山洪的特点为陡涨陡落、流速大、冲击力强,近年来发生的山洪灾害洪水重现期多远超山洪沟治理工程的设防标准(重现期)。在考虑山洪灾害的特点的基础上,提出了在不提高堤顶高程即有限防淹条件下的山洪沟治理思路与具体实施方法:工程措施布局方面,根据山洪沟沿线城镇、集中居民点和重要基础设施的分布合理布置工程措施,形成岸坡防护措施的点状布局;工程措施具体设计方面,在规定的防护构筑物防洪标准和建筑物等级的基础上,局部设计应提高防冲能力,增加基础埋深、提高结构抗滑、抗倾覆安全系数;为了应对超设防标准山洪,山洪沟防洪治理须与山洪沟所在小流域的监测预警系统和群测群防体系等相结合,形成综合防御体系。

For small mountainous watersheds with sparse population, the management of water courses can＇t take high standard under the current specification. These are usually designed with a return period of 10- years and building structure level of grade 5. However, flash flood is characterized by high velocity, strong striking force and severe destruction. In recent years, the return period of flash flood disasters exceed the design standards of flash flood ditch management. Considering the characteristics of flash flood disasters, this paper puts forward the ideas and concrete implementation methods for flood control management of mountain ditches with limited protection.Engineering measures should be laid out according to the distribution of the urban development, concentration on settlements and the important infrastructure in the mountain ditches. Regarding the specific design of engineering measures,local design for protective structures should improve the ability of anti- scour,increase the depth of foundation, improve the structure, and enhance the overturning safety factor against sliding based on flood control standards and regulations on building level. In order to cope with flash floods outside of the design standards, flash flood ditch control management should be combined with the monitoring and early warning system in small watershed. All of the above factors contribute to form an integrated defense system.