成昆铁路泥石流防治工程效益综合分析

SYNTHETIC ANALYSIS ON THE EFFECTIVENESS OF PROTECTION ENGINEERING FOR DEBRIS FLOW ALONG CHENGDU-KUNMING RAILWAY

成昆铁路泥石流防治工作已历时２０余年，投资达２亿余元，共防治了２００余条泥石流沟。为考察已建工程的效益，总结经验教训，加强防治，笔者于１９９２－１９９３年选择了４０条泥石流沟的防治工程进行回访调查。这些工点包括不同类型与不同严重程度的泥石流沟及各类防治工程，具有较好的代表性。调查评估结果为：安全效益良好（Ａ级）的工点２８个，占７０％；一般（Ｂ级）的工点９个，占２２．５％；待改进（Ｃ级）的工点３个，占７．５％。经分析计算，回访工点上所建工程取得的直接减灾效益对工程投入之比达１０．８，证明工程减灾效益远高于投入，投资效益良好。

Since 1972, a great amount of protection engineerings have been built along ChengduKunming Railway which spended over 200 million yuan. These engineerings include chiefly drainge ditches, check dams. bypassing strutures and anti-slide piles. Through paying a systematic return visit and investigation for these engineerings. we found that most of them have made the investment yield well so as to promote the safety of railway operation.In this paper. the debris flow disasters and its protection engineerings along ChengduKunming Railway have been outlined. In order to understand the working situation ofthem. we chose the engineerings in 40 debris flow gullies to be surveyed and analysed by return visit in 1992. Among them. there are 5 debris flow gullies in which the aqueducts were tuilt (taking the proportion of 12. 5% in total) .32 debris flow gullies in which the drainage ditches were constructed (80%) . 17 debris flow gullies in which the check dams were erected (42. 5%) and 3 debris flow gullies in which the anti-slide piles were constructed (7. 5%). Then. We assess the engineerings on the basis of the assessment means which we have formulated and the field investigetion results. Finally the following outcomes have been gained.(1)The effect of the engineerings in 28 debris flow gullies is tetter, whose proportion in total is 70%.(2)The effect of the enginetrings in 9 debris flow gullies is general. whose proportion is 22 .5%.(3)The effect of the engineerings in 3 debris flow gulles is worse, whose proportion is 7. 5%Besides, we draw the tffect of the engineerings from the trend that the debris flow disasters reduce year after year and affirm that the ecnomic tenefit of the protection engineerings is remarkable with their investment.