陕西公路黄土路堑边坡植被防护效应研究

发布时间：2018-03-28 08:17

本文选题：陕西　切入点：黄土边坡　出处：《长安大学》2015年硕士论文

【摘要】：近十多年来,黄土地区快速发展的公路、铁路、市政道路等基础工程建设,加快了当地的经济社会发展,同时形成了大量的黄土路堑边坡,使得当地生态环境不同程度地遭到破坏。通过水土保持界和公路界研究者的不断探索,黄土地区路堑边坡已发展了众多的坡面植被防护技术,有效地防治了坡面侵蚀和冲刷,保证边坡浅表层的稳定性,并改善了路域生态环境。作者通过对陕西省及周边地区通车5~10年的多条高速公路黄土路堑边坡植被防护的详细调查,依据坡面植被恢复的立地条件将其分为三类:坡面直接种植植被护坡技术;改造坡面形态的植被护坡技术;综合护坡技术(植被与工程防护结合),并分析了各自的防护效果及优缺点。同时,调查发现许多坡面植被防护技术的在后期均发生了不同程度的退化,主要是由于边坡坡度(坡比)过大,土壤含水量减少,出现“土壤干层”而造成的。因此,土壤水分是影响黄土路堑边坡植被恢复和重建的关键因素。基于此,论文选择陕西省西安市南郊三处典型黄土路堑植被防护边坡为试验点,通过现场调查、室内外土壤含水率测试等,研究结果表明路堑边坡的坡度(坡比)、坡向、坡位、植被类型和防护模式等是影响边坡土壤含水率的主要因素。其中中坡位大于下坡位,下坡位大于上坡位;陡坡(53°)小于缓坡(29°);阴坡大于阳坡;贴地植被大于直立植被;草灌结合防护模式小于灌木单一防护模式。通过原位双环渗透试验,测定边坡平台离石黄土(Q22eol)和马兰黄土(Q3eol)的渗透系数,分析了不同土体的降雨入渗规律。同时,利用土壤温湿度计,测定了边坡表层土壤的体积含水率,分析了降雨对表层土壤水分的影响规律。以草本植被-小冠花根系为例,配置根土复合体以研究了植被根系与边坡浅表层土壤的相互作用机理。结果表明:影响根土复合体抗剪强度的主要因素有根系密度、根系直径、含水率、须根含量及根系主要分布方式等。植被根系对根土复合体内摩擦角的影响未呈现出规律性,而对粘聚力的影响较大。即主根密度越大,根土复合体的抗剪强度越大;随着根系直径的增大和须根含量增加,根土复合体的抗剪强度呈现出先增大后减小趋势;随着土体含水率的增加,根土复合体的抗剪强度逐渐减小;在数量和直径相同的情况下,根土复合体在受到剪切作用时,垂直根系作用斜生根系水平根系。上述研究成果,对今后陕西省甚至西部黄土地区路堑边坡植被防护具有重要的指导和借鉴意义。
[Abstract]:In the past decade or so, the rapid development of roads, railways, municipal roads and other basic projects in the loess region has accelerated the local economic and social development, and at the same time formed a large number of loess cutting slopes. The local ecological environment has been destroyed to varying degrees. Through the continuous exploration of soil and water conservation and highway researchers, many slope vegetation protection techniques have been developed in the loess region, which has effectively prevented slope erosion and erosion. The stability of the shallow surface layer of the slope is guaranteed and the ecological environment of the road area is improved. The author makes a detailed investigation on the vegetation protection of loess cutting slope of several highways in Shaanxi Province and its surrounding areas, which are open to traffic for 5 to 10 years. According to the site conditions of slope vegetation restoration, it can be divided into three categories: slope protection technology by planting vegetation directly on slope surface, vegetation slope protection technology by transforming slope form. The comprehensive slope protection technology (the combination of vegetation and engineering protection), and the analysis of their respective protective effects and advantages and disadvantages. At the same time, it is found that many slope vegetation protection techniques have been degraded in different degrees in the later stage. It is mainly caused by the slope gradient (slope ratio) is too large, the soil moisture content is reduced, and the "soil dry layer" appears. Therefore, soil moisture is the key factor to affect the vegetation restoration and reconstruction of loess cutting slope. In this paper, three typical loess cutting vegetation protection slopes in the southern suburb of Xi'an, Shaanxi Province are selected as test sites. The results show that the slope of the cutting slope (slope ratio, slope direction, slope position) is measured by field investigation and indoor and outdoor soil moisture content test. Vegetation type and protection model are the main factors affecting soil moisture content of slope, in which the middle slope is larger than the downhill position, the downhill position is larger than the upper slope position, the steep slope is 53 掳) less than the gentle slope, the shade slope is larger than the sunny slope, the vegetation is larger than the vertical vegetation. The combined protection model of grass and irrigation is smaller than the single shrub protection model. The permeability coefficients of slope platform Lishi loess Q22eoland Ma Lan loess Q3eol) are measured by in situ double-ring permeation test, and the rainfall infiltration laws of different soils are analyzed. The volumetric moisture content of the surface soil of the slope was measured by soil temperature and humidity meter, and the effect of rainfall on the surface soil moisture was analyzed. The root system of herbaceous vegetation-small crown flower was taken as an example. The mechanism of interaction between vegetation root system and slope shallow surface soil was studied by collocation of root soil complex. The results showed that root density, root diameter and moisture content were the main factors influencing the shear strength of root soil complex, and the main factors affecting the shear strength of root soil complex were root density, root diameter and moisture content. The content of fibrous root and the main distribution of root system, etc. The influence of vegetation root on the angle of internal friction of root-soil complex is not regular, but the influence on cohesion is greater. That is to say, the more density of main root, the greater the shear strength of root-soil complex; With the increase of root diameter and fibrous root content, the shear strength of root soil complex increased first and then decreased, and the shear strength of root soil complex gradually decreased with the increase of soil moisture content. Under the condition of equal number and diameter, the root soil complex acted on horizontal root system with oblique roots when shearing. It has important guidance and reference significance for the protection of cutting slope vegetation in Shaanxi Province and even the loess region in the west of China.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U417.1

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