国道112线丰宁县城至千松梁段扩建对水土流失的影响及对策

Influences and Countermeasures of Constructing Fengning Line of 112 National Road on Soil and Water Loss

国道 112线丰宁段处于半湿润半干旱的气候条件下 ,当地植被覆盖率低 ,土壤为黄土质母质 ,结构松散 ,黏结力差。该段公路长 5 8 4km ,路线宽度从 6～ 8m扩建为 12m。公路建设只在一定时期内对水土流失有影响 ,且不同部分影响时间不同 ,确定各部分的影响时间为路面 1a ,取土场、弃土场和路基边坡为 5a,临时占地为 3a。根据不同地貌条件下侵蚀模数、面积等计算的原地貌条件下的水土流失量为 748 0t,影响期内的年水土流失量为 145 6 1t。由公路建设引起的水土流失量为 70 8 1t。主要是由于弃土场和公路边坡引起。减轻水土流失的措施对弃土场修建挡渣墙整理后种草植树。

Fengning line of the 112 national road, where the climate belongs to the semi humid and semiarid zone, the vegetation is lower and soil is porous because of its loess parent textile. This road is 58 4 km in length, and 6～8 m in width, which will be reconstructed to 12 m. Constructing road affects the loss of soil and water only in some fixed period, and the affecting time is different in different part of soil, such as it is l a in pavements, 5 a in places where soils were used to road construction, or places where soils were discarded on the road sides and slopes, 3 a in temporary occupied places. According to the erosion modulus and areas under different condition, before the road was constructed, the loss of soil and water from road making is 784 0 t/a, and will be 1 456.1 t/a during constructing period. So, the loss of soil and water from road making is 708.1 t/a, which is mainly resulted from discarded soils, roadsides or slopes. The measure is building walls to block the discarded soils, and plant trees and grasses in them or in the road sides and slopes.