土质浅层边坡的草本植物防护加固效应分析

发布时间：2018-08-28 14:43

【摘要】：近年来,随着我国西部大开发战略的实施,大量铁路、公路、水利水电等工程项目的施工不可避免开挖出大量的工程边坡。对于这些工程边坡不仅要采取必要的支挡措施保证边坡稳定性,而且还应对边坡绿色防护进行进一步研究,以有效的恢复自然生态环境。本文主要探讨草本植物根系固坡的力学机理,评价植物根系对土质浅层边坡土体的加固效果,为植物护坡工程提供充分的理论依据。由于植物根系有一定的影响范围,一般小于2m,因此植物护坡主要是防护浅层不稳定边坡。本文以草本植物香根草根系为研究对象,探讨加入根系后土体的力学特性,分析根系对边坡稳定性的影响。建立含根系土体的基本力学模型,并利用有限元方法对含根系土体的直接剪切试验和抗压试验进行了大量的数值模拟,详细研究了含根系土体内部各力学参数的变化规律,包括不同根系长度、根系分布密度、根系倾斜角度。并对含不同根系形态的土体粘聚力和内摩擦角,与无根系土体的粘聚力和内摩擦角进行了对比分析,发现根系垂直分布于土体中且根系数量越多、长度越长对土体的加固效果越好。通过对粘聚力和内摩擦角值的变化规律研究得到不同根系形态对土体增加的抗剪强度的影响规律,以及不同根系形态下的根-土复合弹性模量的变化规律。最后将前面对含根系土体的参数研究应用到实际边坡中,采用强度折减法对含不同根系形态边坡的稳定性进行分析,进一步探讨含不同根系形态土体的力学参数变化对边坡稳定性的影响规律。发现坡体中含有的植物根系的长度越长、数量越多,则边坡稳定性越高;根系倾斜角度越大,则边坡稳定性越差。通过对含不同根系形态的土体模型的基本力学性能探讨,详细研究了植物根系护坡的作用机理,并对根系加固边坡表层土的实际效果进行了分析,为生态护坡提供了一定的理论依据。因此,开展植物护坡技术的研究和应用具有相当重要的意义。
[Abstract]:In recent years, with the implementation of the western development strategy, a large number of railway, highway, water conservancy and hydropower projects inevitably excavated a large number of engineering slopes. For these engineering slopes, not only the necessary retaining measures should be taken to ensure the slope stability, but also the green protection of the slope should be further studied in order to effectively restore the natural ecological environment. In this paper, the mechanical mechanism of herbaceous root system is discussed, and the reinforcement effect of plant root system on soil mass of shallow soil slope is evaluated, which provides sufficient theoretical basis for plant slope protection project. Because the plant root system has a certain influence range, generally less than 2 m, so plant slope protection is mainly to protect shallow unstable slope. In this paper, the root system of vetiver grass was studied, and the mechanical properties of soil were studied, and the influence of root system on slope stability was analyzed. The basic mechanical model of the soil with roots was established, and the numerical simulation of the direct shear test and compression test of the soil containing root was carried out by using finite element method. The variation of mechanical parameters in the soil containing root was studied in detail. It includes different root length, root distribution density and root tilt angle. The cohesive force and internal friction angle of soil with different root forms were compared with those of non-root soil. It was found that the root system distributed vertically in soil and the number of root system increased. The longer the length, the better the reinforcement effect of soil. The influence of different root forms on the increased shear strength of soil and the variation of root-soil composite elastic modulus under different root forms were obtained by studying the change of cohesion and internal friction angle. Finally, the research on the parameters of the soil with roots is applied to the actual slope, and the stability of the slope with different root forms is analyzed by the strength reduction method. The influence of mechanical parameters of soil with different root forms on slope stability was further discussed. It is found that the longer the length and the more the number of the plant roots contained in the slope, the higher the slope stability and the worse the slope stability is. Based on the discussion of the basic mechanical properties of soil models with different root forms, the mechanism of plant root slope protection is studied in detail, and the actual effect of root system reinforcement on the surface soil of slope is analyzed. It provides certain theoretical basis for ecological slope protection. Therefore, the research and application of plant slope protection technology is of great significance.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948;TU43

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