工程开挖面特征及土壤流失量快速监测方法探讨

工程开挖面是人为水土流失的主要来源之一,准确、快速监测工程开挖面水土流失量具有重要的现实意义。在对全国四大片区不同工程类型开挖面调查的基础上,提出开挖面分类体系,根据下垫面物质分异特征,分均质面和非均质面,根据有无汇水影响,可进一步分为有汇水影响开挖面和无汇水影响开挖面。开挖面下垫面一般紧实度高,干密度大,坡度大多在30°～70°,坡长主要为10 m左右,开挖时间大多在2 a之内。经分析推导,界定开挖面土壤流失量的监测精度为t,水土流失形式主要为沟蚀。综合开挖面特征及水土流失特点,确定工程开挖面土壤流失量监测重点对象为有汇水影响、出现沟蚀、2 a内的开挖面已发生的土壤流失量。在综合比较现有监测技术方法的基础上,提出开挖面土壤流失量快速监测最宜采取三维激光扫描仪。

Discussion on Characteristics of Engineering Excavated Slope and Rapid Monitoring Technology for Soil Loss

Engineering excavated slope is one of the main source of water and soil loss caused by human activity. It is of practical significance to monitor soil and water loss accurately and rapidly. Through investigating different types of engineering excavated slopes in four typical regions, we proposed the classifications of excavated slope. According to the differentiation characteristics of underlying surface, excavated slope is divided into homogeneous surface and heterogeneous surface. And according to the effect of upslope runoff, excavated slope is further divided into surface with upslope runoff and surface without upslope runoff. Generally, the underlying surface of excavated slope has high compactness and bulk density, the gradient varies in the range from 30° to 70°, the length of slope is approximately 10 meters, and the time of excavating is within two years. Through comprehensive analysis, it’s deduced that the soil loss monitoring should be accurate to ton, and the form of soil and water loss is gully erosion mostly. The soil loss monitoring for excavated slope should be focused on slopes affected by upslope surface with gully erosion and excavated within two years. After comparing the existing monitoring technologies, it’s proposed that the best technology for rapidly monitoring the soil loss of excavated slope is 3-D Laser Scanner.