植被发育斜坡非饱和带优先流及根—土环隙流研究

发布时间：2018-04-30 18:37

本文选题：植被发育斜坡 + 滑坡　；参考：《昆明理工大学》2016年博士论文

【摘要】：上个世纪中期以来,受全球变暖趋势强力驱动,极端异常天气事件及其引爆的山区流域天然植被发育斜坡群发性失稳地灾事件不仅发生频率越来越高,而且威胁人们生命财产安全及破坏生态环境,因此深入研究该问题具有重大的现实意义。既有关于降雨型滑坡研究侧重于间接关系的降雨与滑坡和直接联系的地下水与滑坡方面,居于重要基础性地位的降雨向地下水转化过程研究被边缘化。尽管人们已经开始注意到优先流对天然斜坡降雨入渗的影响,但研究水平仍然不高,研究机制有待进一步深入和完善。因此,本文基于室内外试验、理论分析及解析解计算等方法,进行了植被发育斜坡非饱和带优先流路径及根-土环隙流研究。全文开展的主要工作和获得的主要成果如下：1、对头寨沟和段家营试验区5个试验点的天然植被发育斜坡非饱和带土体物理、化学和水理特性进行了野外现场和室内试验,结果表明：头寨沟试验区土体容积含水率、孔隙比、渗透系数、容水度、给水度均大于段家营试验区,而天然密度、干密度、比重、持水度、粘粒及砾粒含量则反之；2种土体均属高压缩性疏松土和酸性土,前者属膨胀土,收缩率空间变异大,且更倾向于有机质土；马卡山土体风化程度低于李凹山。2、从有效大孔隙视角,制作室内大孔隙物理模型,模拟现场染色示踪试验,基于颗粒堆积理论和勾股定理,对大孔隙下限尺度进行了试验界定,得出结论：提出一种较为简便的测试土体大孔隙下限尺度的方法—粒径反算法,并定量计算初步获得了大孔隙的一个下限尺度值为32.46μm;大孔隙功能、亚甲基蓝理化性质、有机质、矿物质均影响大孔隙界定过程；受研究方法、目的和试验仪器设备等条件的约束,大孔隙界定的争议仍然存在。3、采集段家营试验区高盖度玄武岩斜坡典型植被云南松和狗牙根土体,基于水分穿透法,采用方差分析、回归分析方法,进行了对滑坡孕育及发生有显著影响的土体优先流路径特征研究,分析得出结论：植被类型并不能控制土体大孔隙水分运动的整体发展规律,但影响水分穿透曲线的振幅及稳定时间；云南松土体各层大孔隙量大于狗牙根,且2种植被土体均存在大直径大孔隙量小,小直径大孔隙量大的特征；大孔隙尺寸范围受控于植被类型,而尺寸分布受其影响较小；大孔隙特征对不同植被土体水流速率的影响程度不同；有机质和根系含量对不同植被土体大孔隙特征有不同程度影响；颗粒分布对云南松和狗牙根土体各层参量无显著功效；得到大孔隙的又一个下限尺度值为600μm。4、保留坡面原始状态,模拟降雨过程,开展亚甲基蓝染色示踪试验,结合水分穿透法,采集高精度染色剖面图像,基于图像处理、差方分析、回归分析等方法研究了降雨过程中披覆植被斜坡土体优先流分布模式及其影响因素。分析得出结论：木本植被群落土体剖面大孔隙流分布范围更大,连续性程度更低,分化程度更高,染色模式更复杂；高盖度斜坡土体降水更趋于顺坡向垂直入渗；2种植被群落染色覆盖率和染色路径数量均值均随深度增大而减小,且均表现为土体表层和底层的两极分化；团聚体颗粒本身可存在根系通道；活根形成的孔隙系统并不稳定,死根在不同阶段会形成不同的根系通道；根系对木本土体大孔隙流分布的影响程度大,而有机质对草本土体大孔隙流分布的影响程度大;根系尺度并非控制大孔隙尺寸的唯一因素；与植被有关的根系和有机质对大孔隙的形成及规模有积极贡献；大孔隙分布特征显著影响大孔隙流分布特征。5、基于一系列假设,结合套管物理及数学模型,在小雷诺数条件下(层流状态)进行了不同植被群落斜坡土体中根土环隙导流特性研究,并分析了根系对斜坡土体降水入渗影响。得出结论：木本和草本植被群落土体根土环隙尺寸及体积均随土体深度增大而减小：前者土体各层环隙尺寸均小于后者,环隙体积则反之：根系及环隙尺寸的差异造成水分流速最大值发生空间变异；相同环隙流道数量及雷诺数条件下,平均流速、最大流速及环隙贡献率均随深度增加而增大,流量则反之,且前者土体各层流速、流量及贡献率均大于后者；植被类型、植株形态及根系长度、尺寸、数量、体积、生态位等均是影响土体根通道导流特性的重要因素；由根系形成的大孔隙具有小含量大送水量的特征。
[Abstract]:Since the middle of the last century, it has been strongly driven by the trend of global warming. Extreme abnormal weather events and the natural vegetation development slope of the mountain basin, which are detonated, are not only more and more frequent, but also threaten the safety of people's life and property and destroy the ecological environment. Therefore, it is very important to study the problem in depth. There are both rainfall and landslides and direct related groundwater and landslides which focus on the indirect relationship of rainfall and landslides. The research on the process of precipitation into groundwater is marginalized. Although people have begun to notice the effect of preferential flow on rainfall infiltration of natural slopes, the level of research is still However, the research mechanism needs further deepening and improvement. Therefore, based on the indoor and outdoor experiments, theoretical analysis and analytical solution calculation, the study on the preferential flow path of the unsaturated zone and the root soil annular flow in the vegetation development has been carried out. The main work and the main achievements of the full text are as follows: 1 The soil physical, chemical and water characteristics of the natural vegetation development slope of 5 test sites were carried out in field and laboratory tests. The results showed that the soil volume water content, pore ratio, permeability coefficient, water tolerance and water content of the pilot area of the head Zhai Gou test area were greater than those in the family camp test area, while natural density, dry density, specific gravity, water holding degree, The content of clay and gravel is the opposite, and the 2 kinds of soil belong to high compressibility unconsolidated soil and acid soil. The former belongs to expansive soil, and the spatial variation of shrinkage rate is larger and more inclined to organic soil. The weathering degree of the soil is lower than that of.2. The physical model of large pore space in the room is made from the effective macroporous perspective, and the field dyeing tracer test is based on the simulated field. The particle accumulation theory and the Pythagorean theorem are used to define the lower limit scale of the macropores. It is concluded that a simple method for measuring the size of the large pore size of the soil - particle size inverse algorithm is put forward, and the quantitative calculation has preliminarily obtained a lower limit of 32.46 mu m, the macropore function and the physicochemical properties of methylene blue. Organic matter and minerals all affect the process of defining macropores; under the constraints of research methods, purposes and testing instruments and equipment, there is still.3 in the dispute defined by macropores. The typical vegetation of the high coverage basalt slope in the collection section of the household test area is Yunnan pine and the soil of the dog root, based on the water penetration method, the analysis of variance, and the regression analysis. The method, study on the characteristics of the soil preferential flow path which has significant influence on the landslide breeding and occurrence. The conclusion is that the vegetation type can not control the overall development law of the mass pore water movement of the soil, but affects the amplitude and the stability time of the water penetration curve; the large pore volume of the Yunnan loose soil is larger than the dog root, and 2 plants are planted. The large pore size is small, small diameter and large pore volume, and the size range of macropore is controlled by the vegetation type, and the size distribution is less influenced by its size; the characteristics of macropore have different influence on the water flow rate of different vegetation soil, and the organic matter and the root content have different characteristics on the large pore characteristics of different vegetation soil. The particle distribution has no significant effect on the parameters of the soil layers of the Yunnan pine and the dog root. Another lower limit of the large pore is 600 mu m.4, the original state of the slope is preserved, the rainfall process is simulated, the methylene blue staining tracer test is carried out, the high precision dyeing section image is collected with the water penetration method, and the image processing is based on the image processing. Differential analysis, regression analysis and other methods have been used to study the distribution pattern of soil preferential flow in the claped vegetation and its influencing factors during the rainfall process. It is concluded that the distribution of large pore flow in the profile of the woody vegetation community is larger, the degree of continuity is lower, the degree of differentiation is higher, the dyeing model is more complex, and the precipitation of high coverage slope soil is more than that of the soil. The average dyeing coverage rate and the number of dyeing paths of 2 plant communities decreased with the increase of depth, and both showed the polarization of the surface and the bottom of the soil. The aggregate particles could have root channels, the pore system formed by the living roots was not stable, and the dead roots would form different roots at different stages. The root system has a great influence on the distribution of large pore flow in woody soil, and the influence of organic matter on the distribution of large pore flow is great; the root scale is not the only factor to control the size of the macropores; the root and organic matter related to the vegetation have a positive contribution to the formation and scale of the macropores; the distribution of macropores is obvious. Based on a series of assumptions, based on a series of hypotheses, combined with the physical and mathematical models of the cannula, the flow characteristics of the soil annular gap in the slope soil of different vegetation communities were studied under the small Reynolds number condition (laminar flow state), and the effect of root system on the infiltration of slope soil was analyzed. Conclusions: Woody and herbaceous vegetation communities were concluded. The size and volume of soil annular gap decreases with the increase of soil depth: the gap size of each layer in the former is smaller than that of the latter, and the volume of the annular gap is the opposite: the difference in the size of the root and the ring gap causes the spatial variation of the maximum water flow velocity, and the average velocity, the maximum velocity and the annular gap in the same annular channel number and the Reynolds number condition. The contribution rate increased with the depth, and the flow rate was opposite, and the flow rate, the flow rate and the contribution rate of the soil layers were all larger than the latter. The vegetation type, the plant morphology and the root length, the size, the quantity, the volume and the ecological niche were all important factors affecting the conductivity of the soil root channel, and the large pore formed by the root system had small content and large water supply. The characteristics of the quantity.

【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P642.22

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