秦巴山区铁路增建二线的水土流失影响分析

以秦巴山区的3条铁路增建二线工程为例,通过水土流失影响指数评价模型来定量分析、评判山区铁路增建工程的水土流失影响程度.结果表明:襄安线、西康线和安渝线增建二线工程的水土流失影响指数分别为0.240,0.184,0.202,均低于全国铁路建设项目水土流失影响指数的平均值,这说明与新建铁路工程相比,增建二线工程造成的水土流失影响程度相对较小.其主要原因是工程平均占地面积较小(2.54hm²/km)、工程总土石方量(6.99万m³/km)较轻、工程水土流失总量(9 028t/km)不大.在施工过程中,可通过移挖作填、减少弃方、控制施工影响范围、缩短施工期等措施来进一步减弱山区铁路增建工程的水土流失影响,更好地保护山区铁路沿线的生态环境.

Impact of the Railway Constructions of the Second Line on Soil Erosion and Water Loss in Qinling-Daba Mountainous Area

In this study, the impact of constructions of the second line for three railways (i.e. Xiangfan-Ankang railway, Xi’an-Ankang railway, and Ankang-Chongqing railway) on soil and water loss in Qinling-Daba Mountains was quantitatively analyzed and evaluated by using the SWII method. The results showed that the impact indices values of soil erosion and water loss of the foresaid three projects were 0.240, 0.184 and 0.202, respectively, which were lower than the averaged value of impact indices of railways construction projects in China. This also indicated that the railway constructions of the second line would induce less soil and water loss than newly-built railways constructions. The causes for the low indices values of the railway constructions of the second line included less occupation land (2.54hm²/km), little earthwork volume (6.99×10⁴ m³/km), small amount of soil and water loss (9 028 t/km). We could shorten the construction period, reduce wasted excavation and decrease impact area of the construction to mitigate the impact on soil and water loss and protect the eco-environment of mountainous area along the railways.