黄土地区公路边坡植物根系加筋特性研究

发布时间：2018-05-11 11:51

本文选题：黄土地区 + 公路边坡　；参考：《武汉理工大学》2014年硕士论文

【摘要】：随着交通基础设施建设的推进和交通领域的各项深化改革，黄土地区的高等级公路建设得到了大规模发展，同时建设质量在不断的提高，建设水平在不断的提升。黄土具有特殊的形成过程、成分和性质，在降雨条件下无防护边坡容易冲刷破坏，而过去对边坡抗冲刷稳定性基本上都是从土力学的角度去计算分析，对降雨条件下因雨水降落对坡面的溅击冲刷及雨水渗流对坡体基质吸力的减少，从而导致边坡稳定性降低研究甚少。因此，对黄土地区公路边坡植物根系加筋特性进行深入系统地研究显得十分必要，进一步分析黄土的物理力学性质、土质特性对边坡变形机理及变形规律的影响，不同植物根系对土体变形与强度特性的影响。探索适合黄土地区的植物配置及植物根系固土数学模型，为后续子午岭林区公路生态建设顺利推进提供参考，具有重要的研究价值。本论文以青岛至兰州国家高速公路雷家角（陕甘界）至西峰段生态边坡技术研究实际工程为背景，该公路穿越子午岭自然保护区，子午岭林区位于黄河中游，是黄土高原面积最大、植被最好的水源涵养林和绿色屏障，也是黄土高原最大的天然次生林区。边坡生态防护是公路生态环境建设的重要内容，对公路的建设和营运影响较大。本文针对黄土地区公路边坡植物根系加筋特性展开的主要研究内容如下：首先，对黄土工程特性、植被根系加筋试验、植被作用下坡面水力侵蚀、植物根系的固土理论与模型的国内外研究现状进行综述。在此基础上，叙述了雷西高速公路的边坡特点、地形地貌及环境气候条件，并利用X-射线衍射仪和电子扫描显微镜对子午岭隧道进口边坡土体的矿物成分和微观结构进行了研究。其次，通过植物根系与土体的相互作用分析了植物根系对边坡加固稳定的机理。并实地选取雷西高速公路子午岭隧道进口处边坡植被根系复合原状土样，，通过直剪试验和静三轴固结排水试验研究了无根土、草根、灌木及乔木根系加筋土样的应力-应变及强度特性，从得到的试验数据探讨了在不同植物根系加筋作用下土样抗剪强度指标的变化规律。最后，介绍了公路边坡的冲刷机理，分析了植被茎叶及根系对边坡抗冲刷的影响。接着从土体渗流作用力和临界水力梯度对降雨条件下边坡稳定性破坏的机理进行了详细分析，概述了黄土这种非饱和土边坡稳定性的有限元分析理论，接着运用GEO-SLOPE2007（SEEP/W、SLOPE/W及SIGMA/W耦合）软件进行降雨条件下的根-土复合体边坡稳定性分析，将降雨入渗作为土坡稳定分析的重要因素，得出在降雨条件下，植物根系的加筋作用对坡体稳定性有较大影响。研究表明：黄土地区有着特殊的工程地质特性，植物根系对加固、保护边坡体有可支持的力学依据，植物根系对内摩擦角几乎没有影响，而对粘聚力有较大提高，能够有效的稳定边坡。GEO-SLOPE有限元软件通过渗流、边坡及应力-应变三大模块耦合能很好的模拟降雨条件下植物根系对边坡加筋后的应力-应变及稳定性分析。
[Abstract]:With the promotion of the construction of traffic infrastructure and the deepening of the reform in the transportation field, the high grade highway construction in the loess area has been developed in a large scale. At the same time, the quality of the construction is constantly improving and the construction level is constantly improving. The loess has a special formation process, composition and nature, and the unprotected slope is easy to rush under the condition of rainfall. Brush failure, and in the past, the stability of the slope resistance to erosion is basically calculated from the angle of soil mechanics. In the condition of rainfall, the splash erosion and erosion of the slope surface and the decrease of the matrix suction of the slope are reduced, so that the slope stability is reduced very little. Therefore, the reinforcement of the root system of the slope in the loess area is reinforced. It is necessary to make a thorough and systematic study of the characteristics, and further analyze the physical and mechanical properties of the loess, the influence of the soil properties on the deformation mechanism and the deformation law of the slope, the influence of different plant roots to the deformation and strength characteristics of the soil, and explore the suitable mathematical model of the plant distribution and the root soil fixation in the loess region for the follow-up meridian. It is of great research value to provide reference for highway ecological construction in Ridge Forest Region.
This paper is based on the actual project of the ecological slope technology research of the Qingdao to Lanzhou national freeway (Shaanxi Gansu Province) to the Xifeng section. The highway traverses Ziwuling natural reserve and Ziwuling forest area is located in the middle reaches of the Yellow River. It is the largest water source conservation forest and green barrier in the Loess Plateau, and the largest in the Loess Plateau. Natural secondary forest area. Slope ecological protection is an important content of highway ecological environment construction, which has great influence on the construction and operation of highway. The main contents of this paper are as follows: the main research contents of the reinforcement characteristics of the root system of highway slope in the loess area are as follows:
First, the characteristics of the loess engineering, the reinforcement experiment of the vegetation root system, the hydraulic erosion of the slope surface under the action of vegetation, the theory of soil fixation of plant roots and the current research situation at home and abroad are reviewed. On this basis, the slope characteristics, topography and climate conditions of the Lei Xi expressway are described, and the X- ray diffractometer and electronic scanning display are used. The mineral composition and microstructure of the slope at the inlet of Ziwuling tunnel were studied by micromirror.
Secondly, through the interaction between plant root and soil soil, the mechanism of plant root system for slope stabilization is analyzed, and the complex original soil samples of the roots of slope vegetation at the inlet of Ziwuling tunnel of reisi expressway are selected in the field. The root soil, grass roots, shrubs and arbor roots are studied by direct shear test and static three axis consolidation and drainage test. The stress-strain and strength characteristics of samples are investigated. The shear strength indexes of soil samples reinforced by different root systems are discussed based on the obtained experimental data.
Finally, the mechanism of the scour of the highway slope is introduced, and the influence of the stem and leaf and root of the vegetation on the anti scour of the slope is analyzed. Then the mechanism of the slope stability damage under the soil seepage force and the critical hydraulic gradient is analyzed in detail, and the finite element analysis theory of the stability of the unsaturated soil slope is summarized. The GEO-SLOPE2007 (SEEP/W, SLOPE/W and SIGMA/W coupling) software was used to analyze the stability of the soil complex slope under rainfall, and the rainfall infiltration was taken as an important factor for the stability analysis of soil slope, and the effect of the reinforcement effect on the stability of the slope body was greatly influenced by the effect of the reinforcement effect on the plant roots.
The study shows that the loess area has special engineering geological characteristics. The root system has a supporting mechanical basis for strengthening and protecting the slope body. The root system has little influence on the internal friction angle, and the cohesive force is greatly improved. The effective stability of the slope.GEO-SLOPE is through seepage, slope and stress strain three major models. Block coupling can well simulate the stress strain and stability analysis of plant roots reinforced by slope under rainfall.

【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U417.12

【参考文献】