植物纤维毯道路边坡防护技术综合效益评价

为系统评价植物纤维毯水土保持作用对不同雨强的响应以及改良土壤的作用,开展了人工模拟降雨试验和野外小区监测,在模拟降雨试验中,设计4个雨强,测试3种植物纤维毯,降雨历时均为60min。在降雨过程中以5min为间隔收集径流泥沙,并测定径流量和侵蚀泥沙量。在野外小区监测中,通过2007,2010,2013年施工的稻草毯小区,以及2014年施工的椰丝毯、椰丝稻草混合毯和稻草毯小区,评价土壤理化性质对植物纤维毯铺设年限和类型的响应差异。结果表明:在47mm/h及以上雨强下,椰丝毯、椰丝稻草混合毯和稻草毯均能有效减少侵蚀和产流,平均减蚀效益分别为94.92%,86.06%,83.42%,平均减流效益分别为31.59%,45.02%,52.44%,减蚀效益显著优于减流效益。3种植物纤维毯均在47mm/h雨强下减蚀效益和减流效益达到最高,其中最高减蚀效益为椰丝毯(97.54%),最高减流效益为椰丝稻草混合毯(88.26%)。随着雨强增大,减蚀效益和减流效益均不同程度降低,且减流效益降低更快。随着植物纤维毯铺设年限延长,土壤理化性质逐渐改善;铺设1年后,椰丝稻草混合毯改土效果最佳。

Comprehensive Benefit Evaluation on the Protection Technique of Plant Fiber Blanket on the Road Side Slope

In order to systematically estimate the effects of plant fiber blanket on soil and water conservation under different rainfall intensities and on soil amelioration, simulated rainfall experiments and filed monitoring were conducted. In the simulated rainfall experiments, four rainfall intensities were set up and three types of plant fiber blankets were tested. The designed rainfall duration was 60 min. During the rainfall, runoff and sediment were collected every 5 min, of which the runoff volume and sediment yield were measured. In the field monitoring, three plots covered with straw blanket which were constructed in 2007, 2010 and 2013, respectively, and another three plots covered with coir blanket, mixed coir-straw blanket and straw blanket, respectively, which were constructed in 2014, were used to estimate the effects of the plant fiber blanket type and the time after constructed on soil''s physical and chemical properties. The results showed that under 47 mm/h and above rainfall intensities, coir blanket, mixed coir-straw blanket and straw blanket could effectively reduce erosion and runoff, and the average soil loss reduction benefit was 94.92%, 86.06% and 83.42%, respectively, and runoff was reduced by 31.59%, 45.02% and 52.44%, respectively. This indicated that the efficiency of erosion reduction was apparently better than that of runoff reduction. The three kinds of plant fiber blankets had the highest effect of reducing erosion and runoff under 47 mm/h rainfall intensity. The highest erosion reduction efficiency was coir blanket (97.54%), and mixed coir-straw blanket had the highest runoff reduction efficiency (88.26%). With the increasing of rainfall intensities, both the efficiencies of erosion reduction and runoff reduction decreased, and the efficiency of runoff reduction decreased faster. As time after plant fiber blanket constructed prolonged, the physical and chemical properties of the soils covered with plant fiber blanket were gradually improved. Among the three types of plant fiber blankets, mixed coir-straw blanket was the best in soil amelioration after one year''s conduction.