高速公路边坡植物固土力学特性试验研究

发布时间：2018-07-04 09:36

本文选题：高速公路 + 植被护坡　；参考：《中南林业科技大学》2017年硕士论文

【摘要】：高速公路修筑过程中不可避免存在高填深挖,这不仅严重破坏当地生态环境,且容易引起水土流失、塌方、泥石流等地质灾害,对车辆和人身安全造成了很大的威胁。传统的工程护坡技术不仅工程量浩大,耗材多,造价高,形式比较单一,而且永久性的破坏了生态环境,因此,边坡的有效治理是高速公路工程建设中亟待解决的问题。本文依托国家林业局948项目“深路堑边坡景观恢复关键技术引进”(项目编号为101-9968)和大岳高速第八合同段边坡实体工程,以种植的多花木兰和刺槐两种灌木作为研究对象,通过对植物根系分布特征进行分析,对根-土复合体进行剪切和拉拔试验,研究了植物根系的分布形态规律和根-土复合体的力学特性,研究工作的主要创新成果如下。1、通过植物根系形态分布研究发现,刺槐和多花木兰两种灌木的根系形态存在一定的差异,刺槐的主根系作用不明显,水平根系和其上着生出的斜根系较多,相互交织成网状,有利于增强边坡土壤的整体性,多花木兰主根系和副根系比较发达,在护坡中主要起锚杆作用,维系边坡的稳定。2、通过对多花木兰和刺槐根-土复合体室内直剪试验研究发现,植物根系能有效提高土体的抗剪强度。通过对试验数据进行分析和处理,得出根-土复合体的抗剪强度符合库伦定律,根据库仑定律得到多花木兰和刺槐的黏聚力c和内摩擦角φ;在相同条件下,多花木兰根-土复合体的抗剪强度略大于刺槐根-土复合体抗剪强度;3、在相同条件下,混合布根方式的抗剪强度最高,全部斜交布根的抗剪强度次之,全部垂直布根的抗剪强度最小;在相同根系数量和布根方式条件下,随着根系直径的增大,根-土复合体的抗剪强度先增大后减小,当根系直径在1.0mm～1.2mm时,根-土复合体的抗剪强度达最大值。4、通过对多花木兰和刺槐对根-土复合体进行三轴剪试验研究,得到了不同条件下素土和根-土复合体应力-应变曲线;在不同围压和含水率条件下,当轴向应变小于等于2%时,无根素土和根-土复合体应力-应变曲线大多呈线性增加,当轴向应变大于2%时,主应力差增加缓慢,试样呈硬化破坏,最后曲线趋于平稳,主应力差达到最大值。5、通过对多花木兰和刺槐两种植物单根系拉拔试验研究,得到了在相同条件下,多花木兰根系的拉拔强度要比刺槐根系的拉拔强度大;在相同密度不同含水量条件下,多花木兰和刺槐根系的最大拉拔力随含水量的增大呈先增大后减小的趋势,含水量为21.4%左右时,根系拉拔力达最大值;在相同条件下,多花木兰和刺槐根系的最大拉拔力随土样密度的增大而增大,随有效根系的增长而增大。以上研究为探索多花木兰和刺槐两种灌木根-土复合体的力学特性,为这两种植物应用于高速公路边坡综合防治具有重要的参考价值。
[Abstract]:High fill and deep excavation is inevitable in the process of highway construction, which not only seriously damages the local ecological environment, but also easily causes geological disasters such as soil erosion, landslides, debris flow and so on, which poses a great threat to the safety of vehicles and human beings. The traditional engineering slope protection technology not only has a large amount of engineering quantity, many consumables, high cost, but also has a single form, and permanently destroys the ecological environment. Therefore, the effective treatment of slope is an urgent problem to be solved in highway engineering construction. Based on the 948 project of State Forestry Administration, "introduction of key techniques for the restoration of deep cutting slope landscape" (project number 101-9968) and the slope entity engineering of the eighth contract section of Dayue Expressway, this paper takes two kinds of shrubs planted as research objects: multiple Hua Mulan and Robinia pseudoacacia. Based on the analysis of plant root distribution characteristics and the shear and pull-out experiments of root-soil complex, the distribution morphology of plant root system and the mechanical properties of root-soil complex were studied. The main innovative achievements of the research are as follows: 1. Through the study of plant root morphological distribution, it is found that there are some differences in root morphology between Robinia pseudoacacia and multiple Hua Mulan shrub, but the main root function of Robinia pseudoacacia is not obvious. The horizontal root system and the oblique root system on the slope are more, intertwined with each other to form a network, which is beneficial to enhance the integrity of the slope soil. The multiple Hua Mulan main root system and the secondary root system are more developed, which play the role of anchor in the slope protection. In order to maintain the stability of slope, it is found that plant roots can effectively improve the shear strength of soil by direct shear tests of multiple Hua Mulan and Root-soil complex of Robinia pseudoacacia. By analyzing and processing the experimental data, it is concluded that the shear strength of root-soil complex conforms to Coulomb's law. According to Coulomb's law, the cohesive force c and internal friction angle 蠁 of multiple Hua Mulan and Robinia pseudoacacia are obtained. The shear strength of multiple Hua Mulan root-soil complex is slightly higher than that of Robinia pseudoacacia root soil complex. Under the same conditions, the shear strength of mixed brucan is the highest, and the shear strength of all oblique cloth root is the second. The shear strength of all vertical roots was the lowest, and the shear strength of root soil complex increased first and then decreased with the increase of root diameter under the same root number and root style, when the root diameter was 1.0mm~1.2mm, the shear strength of root soil complex increased firstly and then decreased with root diameter increasing. The shear strength of root-soil complex reached the maximum value of .4.The stress-strain curves of root soil and root soil complex under different conditions were obtained by triaxial shear test on root soil complex with multiple Hua Mulan and Robinia pseudoacacia. Under different confining pressure and moisture content, when the axial strain is less than or equal to 2, the stress-strain curves of rootless soil and root-soil complex increase linearly, and when the axial strain is greater than 2, the principal stress difference increases slowly. The specimen showed hardening failure, and the final curve tended to be stable, and the principal stress difference reached the maximum value of .5.Through the experimental study on the single root system of two kinds of plants, multiple Hua Mulan and Robinia pseudoacacia, it was obtained that under the same conditions, The pull-out strength of multiple Hua Mulan roots was higher than that of Robinia pseudoacacia roots, and under the same density and different water content, the maximum pull-out strength of multiple Hua Mulan and Robinia pseudoacacia roots increased first and then decreased with the increase of water content. When the water content was about 21.4%, the root pull-out force reached the maximum value, and under the same conditions, the maximum pull-out force of multi-Hua Mulan and Robinia pseudoacacia roots increased with the increase of soil density and with the increase of effective root system. These studies are of great value for exploring the mechanical properties of multiple Hua Mulan and Robinia pseudoacacia shrub root-soil complexes and for the application of these two plants to the comprehensive control of freeway slope.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.14

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