寨头村黄土边坡包气带水分运移规律研究
发布时间：2019-01-26 09:40
【摘要】：本文依托国家重点基础研究发展计划(973计划)黄土重大灾害成灾机理及灾害链演化规律课题,通过室外渗水试验和室内渗透试验及土壤水分特征曲线测定试验,根据非饱和渗流理论,结合有限元软件模拟室外渗水试验及黄土边坡包气带内水分的运移变化,研究在不同外界因素影响下黄土包气带内水分运移规律。室外渗水试验场地位于陕西省寨头村黄土边坡。根据试验观测数据,分析黄土包气带内水分运移变化。黄土边坡坡面上开挖探槽,深度为1m,并采用环刀进行原位取样。所取土样进行室内渗透试验和土壤水分特征曲线测定试验,得到黄土饱和渗透系数和黄土土壤水分特征曲线。根据试验结果,运用非饱和渗流理论,得到黄土饱和渗透系数与非饱和渗透系数之间的关系,为下一步数值模拟提供模型参数。运用非饱和渗流理论,对寨头村黄土边坡包气带进行水文地质条件概化,建立铅直柱面二维非稳定非饱和渗流数值模型,模拟渗水试验过程中黄土包气带内水分运移变化,并根据实际渗水试验结果对模型进行拟合,分析试验过程中黄土包气带内水分运移分布特征。根据试验结果和模型运行结果,可知渗水试验过程中黄土包气带浅层土壤含水率发生变化,且竖直方向变化范围大于水平方向变化范围,变化深度小于4m。黄土边坡包气带水分运移受三种影响因素:降水条件、蒸发条件和黄土边坡临空面坡度条件。降水影响因素分为持续性小雨(降水时间为24h,降水强度为3mm/h)、短时暴雨(降水时间为2h,降水强度为36mm/h)和无降水;蒸发影响因素分为强蒸发(蒸发强度为0.5mm/h)和弱蒸发(蒸发强度为0.05mm/h);黄土边坡临空面坡比分为1:1、1:0.67和1:0.33。三种影响因素共同作用,共设计18种研究方案。根据非饱和渗流理论,将黄土边坡包气带内水分的运移概化为铅直平面二维非稳定非饱和渗流,结合有限元软件建立相应的数值模型。在不同研究方案下,模型运行结果进行对比、分析,并根据模型结果研究黄土边坡包气带内水分运移变化规律。根据模型运行结果和分析,得到以下结论:1、本次室外渗水试验黄土包气带土壤含水率变化影响范围小于4m。2、黄土包气带深层土壤含水率无明显变化,但仍然存在水分运移。3、持续性小雨(持续时间为24h,降水强度为3mm/h)与短时暴雨(持续时间为2h,降水强度为36mm/h)相比,持续性小雨更易于降水入渗。4、蒸发强度越大,黄土边坡包气带土壤含水率影响变化深度越深,水分运移变化影响作用越明显。5、黄土边坡临空面坡度缓,利于降水入渗补给和蒸发排泄,临空面坡度陡,不利于降水入渗和蒸发排泄。
[Abstract]:In this paper, based on the National key basic Research and Development Program (973 Plan), the mechanism of major loess disasters and the evolution law of the disaster chain are discussed. Through the outdoor seepage test, the indoor permeation test and the soil moisture characteristic curve determination test, According to the theory of unsaturated seepage, combined with the finite element software to simulate the outdoor seepage test and the water migration change in the loess slope aeration zone, the water migration law in the loess aeration zone under the influence of different external factors is studied. Outdoor seepage test site is located in the Loess Slope of Zhai Tou Village, Shaanxi Province. Based on the experimental data, the water migration in loess aeration zone is analyzed. The depth of the trench on the slope of loess slope is 1 m, and the loop knife is used to sample in situ. The saturated permeability coefficient of loess and the characteristic curve of soil moisture of loess were obtained by indoor permeation test and soil moisture characteristic curve measurement. Based on the experimental results, the relationship between the saturated permeability coefficient and the unsaturated permeability coefficient of loess is obtained by using the unsaturated seepage theory, which provides the model parameters for further numerical simulation. By using unsaturated seepage theory, the hydrogeological conditions of unsaturated zone in loess slope of Zatoucun are generalized, and a two-dimensional unsaturated seepage numerical model of vertical column is established to simulate the change of water migration in loess aerated zone during seepage test. The model was fitted according to the actual seepage test results, and the characteristics of water migration and distribution in the loess aeration zone during the test were analyzed. According to the test results and model operation results, it can be seen that the moisture content of shallow soil in the loess aerated zone changes during the seepage test, and the variation range of vertical direction is larger than that of horizontal direction, and the depth of variation is less than 4 m. There are three influencing factors on water transport in aeration zone of loess slope: precipitation condition, evaporation condition and slope condition of loess slope. The influencing factors of precipitation are continuous light rain (precipitation time is 24 hours, precipitation intensity is 3mm/h), short term rainstorm (precipitation time is 2 hours, precipitation intensity is 36mm/h) and no precipitation. The factors affecting evaporation include strong evaporation (evaporation intensity is 0.5mm/h) and weak evaporation (evaporation intensity is 0.05mm/h), and the score of loess slope is 1: 1: 1: 0.67 and 1: 0.33 respectively. A total of 18 kinds of research schemes were designed by the interaction of three kinds of influencing factors. According to the theory of unsaturated seepage, the migration of moisture in the aerated zone of loess slope is generalized to two-dimensional unsaturated seepage in a vertical plane, and the corresponding numerical model is established with the finite element software. Under different research schemes, the results of model operation are compared and analyzed, and according to the model results, the variation of water migration in aeration zone of loess slope is studied. According to the results and analysis of the model, the following conclusions are obtained: 1, the influence range of soil moisture content in loess aeration zone is less than 4m.2, but there is no obvious change in deep soil moisture content in loess aeration zone. But there is still water migration. 3. Persistent light rain (duration is 24 hours, precipitation intensity is 3mm/h) and short term rainstorm (duration is 2 hours, precipitation intensity is 36mm/h), persistent light rain is easier to precipitation infiltration. The greater the evaporation intensity, the deeper the influence of soil moisture content in the aerated zone of loess slope is, and the more obvious the effect of water migration is. 5, the slope of loess slope is slow, which is conducive to precipitation infiltration, recharge and evaporation discharge, and the slope is steep. It is unfavorable to precipitation infiltration and evaporation and excretion.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P641.2
本文编号：2415361
[Abstract]:In this paper, based on the National key basic Research and Development Program (973 Plan), the mechanism of major loess disasters and the evolution law of the disaster chain are discussed. Through the outdoor seepage test, the indoor permeation test and the soil moisture characteristic curve determination test, According to the theory of unsaturated seepage, combined with the finite element software to simulate the outdoor seepage test and the water migration change in the loess slope aeration zone, the water migration law in the loess aeration zone under the influence of different external factors is studied. Outdoor seepage test site is located in the Loess Slope of Zhai Tou Village, Shaanxi Province. Based on the experimental data, the water migration in loess aeration zone is analyzed. The depth of the trench on the slope of loess slope is 1 m, and the loop knife is used to sample in situ. The saturated permeability coefficient of loess and the characteristic curve of soil moisture of loess were obtained by indoor permeation test and soil moisture characteristic curve measurement. Based on the experimental results, the relationship between the saturated permeability coefficient and the unsaturated permeability coefficient of loess is obtained by using the unsaturated seepage theory, which provides the model parameters for further numerical simulation. By using unsaturated seepage theory, the hydrogeological conditions of unsaturated zone in loess slope of Zatoucun are generalized, and a two-dimensional unsaturated seepage numerical model of vertical column is established to simulate the change of water migration in loess aerated zone during seepage test. The model was fitted according to the actual seepage test results, and the characteristics of water migration and distribution in the loess aeration zone during the test were analyzed. According to the test results and model operation results, it can be seen that the moisture content of shallow soil in the loess aerated zone changes during the seepage test, and the variation range of vertical direction is larger than that of horizontal direction, and the depth of variation is less than 4 m. There are three influencing factors on water transport in aeration zone of loess slope: precipitation condition, evaporation condition and slope condition of loess slope. The influencing factors of precipitation are continuous light rain (precipitation time is 24 hours, precipitation intensity is 3mm/h), short term rainstorm (precipitation time is 2 hours, precipitation intensity is 36mm/h) and no precipitation. The factors affecting evaporation include strong evaporation (evaporation intensity is 0.5mm/h) and weak evaporation (evaporation intensity is 0.05mm/h), and the score of loess slope is 1: 1: 1: 0.67 and 1: 0.33 respectively. A total of 18 kinds of research schemes were designed by the interaction of three kinds of influencing factors. According to the theory of unsaturated seepage, the migration of moisture in the aerated zone of loess slope is generalized to two-dimensional unsaturated seepage in a vertical plane, and the corresponding numerical model is established with the finite element software. Under different research schemes, the results of model operation are compared and analyzed, and according to the model results, the variation of water migration in aeration zone of loess slope is studied. According to the results and analysis of the model, the following conclusions are obtained: 1, the influence range of soil moisture content in loess aeration zone is less than 4m.2, but there is no obvious change in deep soil moisture content in loess aeration zone. But there is still water migration. 3. Persistent light rain (duration is 24 hours, precipitation intensity is 3mm/h) and short term rainstorm (duration is 2 hours, precipitation intensity is 36mm/h), persistent light rain is easier to precipitation infiltration. The greater the evaporation intensity, the deeper the influence of soil moisture content in the aerated zone of loess slope is, and the more obvious the effect of water migration is. 5, the slope of loess slope is slow, which is conducive to precipitation infiltration, recharge and evaporation discharge, and the slope is steep. It is unfavorable to precipitation infiltration and evaporation and excretion.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P641.2
【参考文献】
相关期刊论文 前9条
1 谭文清;孙春;胡婧敏;马力;赵彦宁;;GMS在地下水污染质运移数值模拟预测中的应用[J];东北水利水电;2008年05期
2 张茂省;李同录;;黄土滑坡诱发因素及其形成机理研究[J];工程地质学报;2011年04期
3 雷宇;谢锋涛;朱学坤;;沥青路面渗水试验检测方法分析与改进[J];山西建筑;2007年09期
4 孙从军;韩振波;赵振;范宇;;地下水数值模拟的研究与应用进展[J];环境工程;2013年05期
5 阿米娜·毛力提别克;;沥青路面渗水问题及渗水试验方法探析[J];交通标准化;2014年04期
6 郝治福;康绍忠;;地下水系统数值模拟的研究现状和发展趋势[J];水利水电科技进展;2006年01期
7 任印国;柳华武;李明良;许建廷;刘超;;石家庄市东部平原FEFLOW地下水数值模拟与研究[J];水文;2009年05期
8 戚国庆,黄润秋,速宝玉,胡云进,詹美礼;岩质边坡降雨入渗过程的数值模拟[J];岩石力学与工程学报;2003年04期
9 蔡燕霞;申爱琴;郭寅川;王德强;;沥青混合料动水破坏行为与动力渗水试验模拟[J];长安大学学报(自然科学版);2015年02期
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