【作者】 郭颖；

【导师】 单炜；

【作者基本信息】 东北林业大学 ， 森林工程， 2013， 博士

【摘要】 近100年来,全球气候变化进程不断加快,从而引发许多工程地质问题。在黑龙江省,随着高等级公路建设快速发展,公路路堑边坡失稳现象不断出现。寻求与路域生态环境建设相结合的合理的边坡防护方式、方法,完善土质路堑边坡防护理论与防护方法,成为寒区公路建设亟待解决的问题。在我国东北高纬度季节冻土地区,土质路堑边坡浅层水温条件变化剧烈,直接影响边坡稳定。护坡植物根系吸水和蒸腾作用,能够调节坡面浅层土体含水率；同时,根系深入土中,与土壤形成复合体,改变了坡面浅层土体力学参数,进而对边坡稳定系数产生影响。另外,从植物生理特性和地域环境适应性角度,采用多种方法研究,选择抗逆性强、又能有效护坡、美化路与环境的护坡植物,也是本文内容之一本文依托黑龙江省科技攻关项目《东北季节冻土地区高等级公路土质路堑边坡植物防护体系研究》(GZ07C401)、国际滑坡研究计划项目《Research on vegetation protection system for highway soil slope in seasonal frozen regions》(IPL-132)、黑龙江省交通厅重点科技项目《高等级公路植物稳定边坡与绿化研究》确定选题,并开展相关研究工作。通过对同三高速公路佳木斯至哈尔滨段路堑边坡病害调查,选择确定研究区和试验研究路段；通过现场取样和室内实验,得到边坡土体容重、密度、渗透系数、颗粒组成、界限含水率等基本物理指标；通过室内三轴实验,得出素土和含根土体粘聚力、内摩擦角、变形模量随密度、含水率、冻融次数的变化规律。结果表明：未冻融无根土体和含根土体粘聚力、内摩擦角、变形模量均随土体密度增加而增大；土体含水率小于最佳含水率时,粘聚力随含水率增加而增大,土体含水率大于最佳含水率时,粘聚力随含水率增加而减小；土体内摩擦角随含水率增加而减小；土体变形模量随含水率增加而减小。经历冻融过程的无根土体、含根土体的力学参数变化与未经历冻融无根土体规律相近,但在不同状态下各参数变化幅度不同；通过对胡枝子、紫穗槐、草皮护坡边坡土体含水率沿深度变化数据,结合植物生理学、气象学、土壤物理学理论,得出护坡植物根系在边坡土体中的分布规律及植物根系和冻融共同作用下边坡土体中水分迁移和分布规律。结果表明：采用灌木植物护坡,通过植物根系吸水和叶面蒸腾,可有效降低边坡土体浅层含水率,胡枝子、紫穗槐根系对局坡面以下1OOcm范围内土体含水率有显著影响；通过对胡枝子、紫穗槐和沙棘的根系形态分析,结合素土、紫穗槐、胡枝子根系复合土现场直剪试验,揭示植物根系固土护坡的力学机理。结果表明：在距坡面60cm范围内,选定护坡灌木根系复合土抗剪强度是无根系土抗剪强度2倍左右；通过春融期边坡土体轻型贯入试验,结合边坡土体温度测量数据,得到土体温度场和强度场分布,结合土力学理论和土体力学指标室内三轴试验结果,得到土体抗剪强度与含水率变化关系；运用土壤物理学、传热学理论,结合对研究路段边坡土体温度、含水率变化监测数据分析,得出冻融过程中不同滑坡植物覆盖条件下、不同深度边坡土体含水率随温度变化规律。结果表明：在土体冻结过程中,未冻水分会向冻结区迁移,在冻结区局部分凝成冰。在春融期,冻结土体从坡面和土体冻结层以下两个方向开始融化,坡面浅层土体融化水分不能及时下渗导致春融期坡面浅层土体含水率迅速升高；通过基于有效应力法的春融期季节冻土地区土质路堑边坡稳定安全系数公式推导,进一步分析了土体物理、力学参数和边坡几何参数对边坡稳定性的影响；通过基于强度折减有限元模拟计算,求得不同覆盖条件下监测断面最不利季节边坡稳定安全系数。结果表明：在春融期,采用草皮护坡,监测断面边坡均处于临界失稳状态,采用胡枝子护坡,监测断面边坡处于稳定状态；通过边坡土体饱和不排水环剪试验和残余强度环剪试验,研究边坡滑动过程中土体力学参数变化规律。结果表明：边坡土体表观摩擦角为22.2。,残余强度下表观摩擦角为7.6。；结合研究区滑坡实例分析,验证了分析方法的正确性和分析结果的准确性；基于遥感数据和气象数据,通过对植被指数与气象因子关系的研究,分别建立气温、降水量和日照等气象因子与植被指数的数学关系模型,反演气象因子,结合地形高程数据和植物生长特性,建立紫穗槐、胡枝子和沙棘等植物生长适应性的评价指标体系,并进行空间适应性评价。结果表明：选定护坡植物在黑龙江省具有良好生长适应条件。更多还原

【Abstract】 For nearly100years, the process of global climate changing continues to accelerate, which cause many engineering geological problems. In Heilongjiang Province, With the rapid development of highway construction, the instability of cutting slope continue to emerge. It is urgent problems to be solved to seek reasonable method of slope protection which could combinate with the ecological environment of the road region, and to give a clear answer on the theory and practice.In high-latitude seasonal frozen areas of Northeast China, water temperatures in shallow slope change largely, which could impact on slope stability directly. Root absorbent and transpiration of slope protection plant not only could be able to adjust the moisture of shallow slope but also could improve the mechanical parameters of the soil for the reason of its roots penetrating into the soil and forming root-soil complex. In addition, from the respects of physiology and adaptability in geographical environment, using kinds of methods, selecting protection plants which both has strong resistance, also can protect beautify the slope is also one of content in this article.Relying on the research project of Heilongjiang provincial Science and Technology Department (GZ07C401), the Key project of Heilongjiang provincial Transportation Department "Highway Slope Stability and Greening by Vegetation in Cold Regions", and the project of International Program on Landslides" Research on vegetation protection system for highway soil slope in seasonal frozen regions"(IPL-132), this article determined its topics, and began to carry out research work.Through the survey of instability cutting slope along the Tongsan Highway from Jiamusi to Harbin, study area and study section was selected. Through on-site sampling and laboratory experiments, the basic physical indicators of the soil, such as density, permeability coefficient, particle composition were obtained. Through triaxial test, for soil and root-soil, the variation of the cohesion, internal friction angle, deformation modulus varing with density, moisture, freezing-thawing cycles was got. The results show that:Both for unfrozen soil and for unfrozen root-soil, their cohesion, internal friction angle, deformation modulus are all increased with the increase of soil density; when soil moisture is smaller than optimum moisture, the cohesion is increased with the increase of soil moisture; when soil moisture is bigger than optimum moisture, the cohesion is decreased with the increase of soil moisture; The internal friction angle and the deformation modulus of the soil is decreased with the increase of soil moisture; After freezing-thawing cycles, both for the soil and root-soil, their mechanics parameters is similar with unfrozen soil, just not have the same changing size. For three kinds of plant:turf, Lespedeza, Amorpha, through the data analysis of the moisture in different depth, using the theory of plant physiology, meteorology, soil physics, both the distribution of root system in cutting slope and the law of moisture migration and distribution under the joint action of plant roots and freeze-thaw was got. The results show that:Through absorbent root and leaf transpiration, shrubby plants (lespedeza, Amorpha)on the slope can effectively reduce the shallow moisture of the slope, especially for the soil boby within the scope of100cm below the surfface. Through shape analysis of root combining with site direct shear tests of root-soil, the mechanical mechanism of plant roots protecting the slope was got. The results show that:shear strength of root-soil within60cm is about2times of shear strength of the soil. Through light penetration testing, combined with temperature measurement data, field distribution of slope body’s temperature and shear strength were got, combining with soil mechanics theory and triaxial test results, the relationship between the shear strength and soil moisture was got. Using the the theory of soil physics, heat transfer, combining with the monitoring data of slope body’s temperature and moisture, in diferrent plant cover condition and different slope depth, the law of moisture distribution changing with the temperature was got. The results show that:During the soil freezing process, unfrozen water will migrate to a frozen zone, and part of them become into ice. During the spring melt period, frozen soil layer began to melt from two directions:the surrface and deep unfrozen soil, the melt water in shallow slope can not penetrate in time, result in the moisture in the shallow layer is very hight. Through the derivation of slope’s safety factor, which is based on the effective stress, the impact of physical, mechanical and geometry parameters on slope stability was analized furtherly. Based on strength Less finite element, the safety factor under different coverage conditions and in the most unfavorable season was got. The results show that:In the melting period of spring, if the turf served as protecting slope plant, two monitoring sections of the slope are all in critical state of instability state, if Lespedeza served as protecting slope plant, they are in stable state Through saturated undrained ring shear test and residual strength ring shear test, the variation of physical parameters in sliding process was studied. The results show that:view friction angle of the slope body is22.2°, view friction angle of the slope body in residual strength is7.6°. Combining with landslide case analysis, correctness of the analysis method and analysis results was verified. Based on remote sensing data and meteorological data, through the study of relationship between vegetation indices and meteorological factors, mathematical model between vegetation index and temperature, precipitation and sunshine was built, then meteorological factors was anti-derivated.Combinning with the terrain elevation data and plant growth characteristics, for Amorpha, Lespedeza and sea buckthorn, evaluation system of plant adaptive growth was established, and conduct space adaptability evaluation. The results show that:in Heilongjiang Province. the selected plants have good growth adaptation.更多还原