高速公路建设中不同类型弃土场的土壤流失特征

Soil loss characteristics in different types of dump during expressway construction

以沪蓉西高速公路(上海至成都高速公路西段)湖北宜长段(宜昌至长阳县)弃土场为研究对象,通过观测天然降雨、土壤、植物和土壤流失量等因子,探讨不同类型弃土场的土壤流失特性。结果表明:1)降雨量与降雨强度的乘积(PI)和次降雨造成的单位面积土壤流失量(E)之间,表现出较好的一元正线性相关关系。在不考虑影响坡面土壤流失的其他因素的前提下,随着降雨量和降雨强度乘积的增加,土壤流失量逐渐加大。2)采取工程措施和生物措施综合防护,可以有效减少弃土场的土壤流失量。3)弃土场表土物质组成对土壤流失起着重要作用,表土受雨水冲刷,砾石含量会逐渐增大,土壤流失量逐渐减小。

Taking the Yichang part of the Hurongxi expressway as an example for studying the characteristics of soil loss of dump, the factors, such as prepicitation, soil, plant and amount of soil loss were observed. The results showed that ： 1） The relation between amount of soil loss and product of prepicitation and railfall intensity was found to be a better linearity. While taking no account of other factors in affecting the soil loss of slope, with the PI increaing, the amount of soil loss gradually enlarged. 2） Comparing the dump taken on the bio-measure and engineering measure with the unprotected one, soil loss of protected dump is reduced more than the unprotected dump. 3） Physical composition of dump surface affects the amount of soil loss. When the dump surface damaged by rain, the content of gravel became bigger, and then the amount of soil loss would become smaller gradually.