【作者】 齐娜；

【导师】 王玉杰；

【作者基本信息】 北京林业大学 ， 水土保持， 2010， 硕士

【摘要】 本论文结合“十一五”国家科技支撑项目“重庆北部水源区水源涵养林构建技术试验示范(2006BAD03A 1 802)”,采用实验对比,相关分析和主成分分析等方法研究了重庆缙云山五种典型地类(针阔混交林、常绿阔叶林、楠竹林、灌木林和农地)原状土和扰动土的抗剪强度特征及影响因素,以期为缙云山林地土壤抗侵蚀研究提供科学依据。研究的主要结果为：对五种林分的土壤结构和理化性质分析表明：各林地土壤砂粒含量相对较低,其中楠竹林的物理性粘粒含量最低,为31.33%。林地的团聚体含量大于灌木林地、农地。微团聚体团聚度和各类孔隙度从表层(A层)到底层(C层),均逐渐降低,而土壤容重由A层到C层容重呈增加趋势。各典型林地pH值、有机质含量、阳离子含量、速效氮、速效磷、速效钾、全氮、全磷和全钾含量大小排列各不相同,除pH值、阳离子交换量和全钾含量外,其它各指标随着土壤深度的增加而减小对各典型林地的土壤抗剪强度特征分析表明：原状土的粘聚力值(c)在土壤剖面方向呈增大趋势,其中针阔混交林原状土的的平均c最大(42.09kPa)。内摩擦角((?))基本没有变化,农地原状土的平均(?)最大(27.31。)。对扰动土分别进行三组实验：1)直剪试验；2)不固结不排水试验；3)固结不排水试验。直剪和不固结不排水试验结果表明,这两处理方式下各典型林地土壤的内摩擦角、粘聚力值并无明显规律性,直剪试验中粘聚力的平均值c以灌木林地最大(16.51 kPa),内摩擦角(?)平均值以楠竹林地最大(25.60°)。固结不排水试验结果表明,土壤有效粘聚力与总粘聚力的变化趋势相同,而有效内摩擦角与总内摩擦角的变化趋势具有明显差别。抗剪强度与土壤结构和理化性质指标的相关分析结果表明：1),原状土的理化性质各指标与土壤抗剪强度值之间相关性较好,相关系数为0.824；2),在扰动土直剪、不固结不排水和固结不排水试验,抗剪强度与土壤结构各指标和理化性质指标之间相关性均较高,相关系数在0.9到0.928之间。采用主成分分析法对影响各典型林地土壤抗剪特性的影响因子分析结果表明：1)各典型林地原状土抗剪特性影响因子的平均综合指数为30.34,其排列顺序为灌木林(40.74)>常绿阔叶林(30.63)>针阔混交林(28.78)>楠竹林(28.71)>农地(25.46)；2)对扰动土分析,①.直剪试验中,各典型林地土壤抗剪特性影响因子的平均综合指数为29.08,其排列顺序为灌木林(51.99)>农地(27.57)>针阔混交林(27.46)>常绿阔叶林(24.39)>楠竹林(19.72)。②.不固结不排水试验中,其平均综合指数为23.69,排列顺序为针阔混交林(25.27)>灌木林(24.23)>常绿阔叶林(23.88)>农地(21.92)>楠竹林(21.49)。③.固结不排水试验中,总应力方式下,其平均综合指数为77.57,排列顺序为灌木林(109.91)>常绿阔叶林(74.82)>针阔混交林(72.20)>楠竹林(69.63)>农地(69.37)；有效应力下,其综合指数为24.12,排列顺序为灌木林(52.78)>针阔混交林(29.05)>农地(18.67)>楠竹林(14.45)>常绿阔叶林(]2.84)。更多还原

【Abstract】 This study was supported by the "Eleventh Five-year" National Technology Support Project "Experiment& Demonstration of the Construction Technology of Water-Conservation-Forest in the northern Water Source Area, Chongqing (2006BAD03A1802)". In this thesis, Experiment, Correlation Analysis and Principal Component Analysis were employed to study the shear strength characteristics and affecting factors of the undisturbed soil and disturbed soil from typical Mixed Coniferous forest, Evergreen-Broadleaf forest, Bamboo, Shrub and Farm land, in Jinyun Mountain Area, Chongqing.Analysis on the structure and physical and chemical properties of soil indicated that:the content of sand in soil from the five typical land types is relatively low, while the physical clay content in the soil from Bamboo Land is the lowest, about 31.33%. The content of Aggregates in the soil from forest land is more than Shrub Land and Farmland. The Aaggregate Degree and various types of Porosity decrease, while the Soil Bulk Density increases from the surface layer(A layer) to the bottom layer(C layer). Organic Matter Content, pH, Cation Content, Available Nitrogen, Phosphorus, Potassium, Total Nitrogen, Total Phosphorus and Potassium of the soil form typical forest lands array in different order. All of these indicators, except pH Value, Cation Exchange Capacity and Potassium, are decreasing with the depth of soil.The analysis of shear strength of soil from the five land types showed that:Cohesion Value(c) of undisturbed soil gradually increases with the depth of the soil, while the average c of soil from Mixed Coniferous forest is the biggest, about 42.09KPa. The Internal Friction Angle(φ) of the soil from all the five land types doesn’t change with the depth of soil, andφof soil from Farmland is the biggest, about 27.31°. The c andφof disturbed soil were tested in three conditions, direct shear test, undrained test and consolidated undrained test. In the direct shear test, there is no significant change in c andφfrom A layer to C layer, and the c of soil from Shrub Land andφof soil from Bamboo Land are the largest, about 16.51kPa 25.6°respectively. In the undrained test, there is also no significant regularity in c andφfrom A layer to C layer. In the consolidated undrained test, the trends of the effective soil cohesive force and the total value of the cohesive force are the same, while trends of effectiveφand the total value ofφare different.The shear strength of undisturbed soil is closely related with soil properties indices, the correlation coefficient between them is 0.824. In the direct shear test, undrained test and consolidated undrained test, the correlation coefficient between shear strength of disturbed soil and soil properties indices is very high, between 0.90 and 0.928. Principal Component Analysis showed that:1), the average Comprehensive Index (CI)of the factors which affect the shear characteristics of soil from different land types is 30.34, the order of CI is Shrub Land (40.74), Evergreen-broadleaf forest (30.63), Mixed Forest (28.78), Bamboo Land (28.71) and Farmland(25.46);2)On the disturbed soil analysis:①. In the direct shear test, the average CI is 29.08, the order of CI is Shrub Land (51.99), Farmland(27.57), Mixed Forest (27.46), Evergreen-broadleaf forest (24.39), Bamboo Land(19.72);②. In the undrained test, the average CI is 23.69, the order of CI is Mixed Coniferous (25.27), Shrub forest (24.23), Evergreen-broadleaf forest (23.88),Farmland (21.92), Bamboo Land(21.49);③. In the consolidated undrained test, the average CI under total stress is 77.57, the order of CI is Shrub forest (109.91), Evergreen-broadleaf forest (74.82), Mixed Forest (72.20), Bamboo Land (69.63), Farmland (69.37), while the CI under effective stress is 24.12, the order of CI is Shrub (52.78), Mixed Forest (29.05), Farmland (18.67), Bamboo Land (14.45), Evergreen-broadleaf forest (12.84).更多还原