| For nearly 10 years, basic engineering constructions which have the rapid development, such as highway, railway, municipal roads and so on, form a large number of loess cutting slopes which damage the local ecological environment in different degree in the loess area. There are many vegetation protection technologies used to protect loess cut slope, which work in prevention and treatment of loess hillslope erosion and scour significant effect, effectively ensure the stability of the slope shallow, and improve the expressway environment, through continuously explore of researchers in the field of soil and water conservation and the field of highway.According to site conditions of the slope vegetation restoration, protection forms of Highway slope can be divided into three categories: direct vegetated slope revetment technology; reconstruction slope form of vegetation protection technology; vegetation and engineering of integrated slope technology, and their protective effects and the advantages and disadvantages are analyzed, through detailed investigation of vegetation protection loess cutting slopes of many highways which have opened 5-10 years. At the same time, the survey found that many slope vegetation protection technologies have the different degree of degradation in the late, mainly due to the large slope, reducing soil moisture content, and appearing "soil dry layer". Therefore, the soil moisture is the key factor influencing the loess cutting slope vegetation restoration. Based on this, choosing typical loess cutting slope vegetation protection in South Third Ring Road, Park Road and Beltway of Xi’an, Shaanxi Province as test point, it can be found that gradient, slope direction, slope position, vegetation type and protection mode are the main factors influencing the slope soil moisture through the indoor moisture content. Soil moisture content of gentle slope is greater than the steep slope. Soil moisture of shady slope is greater than sunny slope. Soil moisture of middle slope is greater than downhill position and Soil moisture of downhill position is larger than the uphill position. Soil moisture of creeping vegetation is greater than the standing vegetation. Through the double-ring permeability test in the field, determine the permeability coefficient of Malan loess in third platform and Lishi loess in second platform, and analyze the regularity of rainfall infiltration of different soils. Through soil temperature and humidity meter, determine the surface soil moisture in the field and analyze the influence law of rainfall on surface soil moisture. Selecting the roots of crown vetch, we remodel soil-root composites in different conditions and take indoor direct shear tests. The results show that root density, root diameter, moisture of soil-root composites, fibrous content and mainly root distributed manners are the main factors affecting the root soil composite shear strength. These factors have no obvious impact law on vivo friction angle of soil-root composites, but have a greater impact on cohesion. With the increasing of taproot density, the shear strength of soil-root composites increases. With the root diameter increases, the shear strength of the soil-root composites exhibits trend of first increase and then decrease. With the increasing of moisture, the shear strength of soil-root composites decreases. With the increasing content of fibrous roots, the shear strength of soil-root composites first increases and then decreases. When the number and diameter are same, the shear strength of soil-root composites shows the law: the vertical roots> the declining roots > the horizontal roots. The research results provide important guidance and reference for the cut slope vegetation protection of Shaanxi Province even in western loess in the future. |
PDF Full Text Request