本文選題：植被發(fā)育斜坡　切入點：滑坡　出處：《昆明理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：山區(qū)流域植被發(fā)育斜坡的失穩(wěn)往往尾隨強降雨發(fā)生,降雨入滲引起的地下水位上升是導致斜坡失穩(wěn)的主要原因,而飽和滲透系數(shù)是評價土體的滲透特性的主要參數(shù),大孔隙分布規(guī)律及其結(jié)構(gòu)特征是影響土體滲透性的關(guān)鍵因素,因此對植被發(fā)育斜坡土體大孔隙和滲透性展開研究是很有必要的。本文以頭寨溝植被發(fā)育斜坡土體為研究對象,采用現(xiàn)場調(diào)查、現(xiàn)場試驗、室內(nèi)試驗和送樣分析等手段對植被發(fā)育斜坡區(qū)域地質(zhì)特征、氣候特征和土體的物理性質(zhì)等進行全面分析；利用CT掃描技術(shù)和圖像處理技術(shù)獲得該區(qū)土體大孔隙尺寸分布規(guī)律和形狀特征；利用環(huán)刀法測定土體飽和滲透系數(shù),并與毛細管束模型預測的飽和滲透系數(shù)進行對比研究。具體的工作和得到的結(jié)論如下：(1)對試驗點植被發(fā)育斜坡區(qū)域地質(zhì)調(diào)查、氣象監(jiān)測和土體物理性質(zhì)等進行分析。得到結(jié)論：頭寨溝滑源區(qū)較坡腳降雨量偏大,而氣溫偏低；試驗點土體天然密度、干密度和比重較草本植被區(qū)土體偏小,天然含水率和孔隙比卻偏大；試驗點土體有機質(zhì)含量比農(nóng)業(yè)土壤高6-10倍,土體中根系主要分布于表層50cm范圍內(nèi),微生物類型以細菌為主,微生物總量隨深度有遞減的趨勢；試驗點土體粘粒的礦物成分主要是石英、蒙脫石和斜長石等,個別樣品還含有少量高嶺石。(2)運用CT掃描技術(shù)獲得土體大孔隙分布特征和形狀特征。得到結(jié)論：CT掃描技術(shù)用于分析土體大孔隙精度較高；大孔隙度隨深度增加有減小的趨勢,各孔徑級別的大孔隙數(shù)量隨孔徑級別增加呈指數(shù)規(guī)律遞減；隨深度增加土體大孔隙形狀越狹長；大孔隙等效直徑越大其輪廓越粗糙。(3)優(yōu)先流的觀察,飽和滲透系數(shù)的測定以及與預測結(jié)果的對比分析。得到結(jié)論：優(yōu)先流的主要通道為動物洞穴、根土間隙、干縮裂縫和腐爛根系通道等大孔隙；環(huán)刀法測定的飽和滲透系數(shù)隨深度增加呈遞減的趨勢；根據(jù)毛細管束模型預測所得的飽和滲透系數(shù)與實測值存在一定偏差,但兩者在同一數(shù)量級內(nèi)；修正后的毛細管束模型預測值精度明顯提高,修正后的預測值與實測值的均方根誤差由0.64減小到0.41。
[Abstract]:The instability of vegetation development slopes in mountainous areas is often followed by heavy rainfall. The rise of groundwater level caused by rainfall infiltration is the main cause of slope instability, and the saturation permeability coefficient is the main parameter to evaluate the permeability characteristics of soil. The distribution law of macropores and its structural characteristics are the key factors affecting soil permeability. Therefore, it is necessary to study the macroporosity and permeability of soil on the slope of vegetation development. This paper takes the soil mass of Touzhaigou vegetation development slope as the research object. By means of field investigation, field test, laboratory test and sample delivery analysis, the geological characteristics, climate characteristics and physical properties of soil in the slope region of vegetation development are comprehensively analyzed. By using CT scanning technique and image processing technique, the size distribution and shape characteristics of macroporous soil in this area are obtained, and the saturated permeability coefficient of soil is measured by using the annular knife method. And compared with the saturated permeability coefficient predicted by the capillary beam model. The concrete work and the conclusion obtained are as follows: 1) the regional geological survey of the vegetation development slope in the experimental site. The results of meteorological monitoring and physical properties of soil are as follows: the rainfall in Touzhaigou sliding source area is higher than that in the foot of slope, but the temperature is lower, and the natural density, dry density and specific gravity of soil in the test site are smaller than that in herbaceous vegetation area. The content of organic matter in the soil is 6-10 times higher than that in the agricultural soil, the root system of the soil is mainly distributed in the surface layer of 50cm, the microorganism type is mainly bacteria, and the total amount of microorganism is decreasing with the depth of the soil, and the content of organic matter in the soil is 6-10 times higher than that of the agricultural soil. The mineral composition of clay in the soil of the test site is mainly quartz, montmorillonite and plagioclase, etc. Some samples also contain a small amount of kaolinite. 2) the distribution and shape characteristics of macropores in soil are obtained by CT scanning technique. It is concluded that the accuracy of macroporosity analysis is high, and the macroporosity tends to decrease with the increase of soil depth. The number of macropores at each pore size level decreases exponentially with the increase of pore size level; with the increase of depth, the shape of macropore is longer and narrower; the larger the equivalent diameter of macropore is, the rougher the contour is. It is concluded that the main channels of preferential flow are animal caves, root soil gaps, dry shrinkage cracks and rotting root channels. The saturation permeability coefficient measured by the annular knife method is decreasing with the increase of the depth, the saturation permeability coefficient predicted by the capillary bundle model has a certain deviation from the measured value, but both of them are in the same order of magnitude. The precision of the modified capillary bundle model is improved obviously, and the root mean square error between the predicted value and the measured value is reduced from 0.64 to 0.41.
【學位授予單位】：昆明理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P642.2

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