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暴雨型滑坡灾害形成机理及预测方法研究 【作者】魏丽 【导师】郑有飞

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暴雨型滑坡灾害形成机理及预测方法研究

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【作者】魏丽导师郑有飞水利论文;f/m4WZ N@"| Z ~W
【作者基本信息】南京信息工程大学,大气物理学与大气环境,2005年,博士水利论文g0xG&] D;N

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!T;\bP+mU0【中文摘要】 本文针对暴雨型滑坡灾害预报预警服务的需要,以江西为研究区域,从暴雨型滑坡灾害形成机理及预测理论入手,通过八个滑坡灾害易发点的监测试验,系统地研究了大气降水对地下水位、孔隙水压力、滑坡土体应力及滑坡稳定性的影响。探讨了植被覆盖与滑坡的关系。根据历史资料,进行了滑坡风险区划和暴雨型滑坡的时空分布特征分析。应用统计学和试验研究相结合的方法,提出了滑坡体发生滑动的临界雨量指标。开发了基于Web-GIS的暴雨型滑坡灾害预报预警业务系统,并进行了业务试验。(1) 揭示了江西省暴雨型滑坡时空分布特征。江西省多为浅层滑坡,结构以整体式滑坡为主;丘陵区滑坡占多数;较陡区滑坡处数、体积最多;滑坡多发生于20~35°的斜坡及海拔100~400m地段;滑坡主要发生在雨季,5~7月发生的滑坡占总数的87%,发生在6月的占70%;日降水量为100~400mm时发生的滑坡占总数的70%;滑坡灾害发生多与降雨同步,少数滞后;年暴雨日在5~6日的区域较易发生滑坡。(2) 提出了用日综合雨量预报暴雨型滑坡的概念和指标。根据1960s年代以来资料统计分析,降水诱发的滑坡不仅取决于当日雨量,而且与前期过程降水量有关,某日降水...更多量对滑坡的作用可持续1~10天。在日综合雨量计算模型中引入了衰减系数的概念,用于计算诱发滑坡的有效雨量。分析了不同降水过程蒸散量的日变化及对日综合雨量的影响。(3) 揭示了降水导致滑坡的动态过程和机理。降水对滑坡的作用是一个动态过程,暴雨期间发生的浅层土质滑坡是受到短时间内强降水的作用,滑坡土体因降雨入渗很快达到饱和状态,导致短期内地面位移加剧,土体应力发生较大变化,使土体饱和度及孔隙水压力上升,降低了斜坡物质的抗滑力,随着时间推移,最终导致滑坡发生。(4) 揭示了不同类型滑坡发生滑动的大气降水临界值,为滑坡灾害预测提供了依据。在江西省滑坡灾害易发区建立8个监测点,其中包括1个重要监测点和7个一般监测点。对各监测点地下水位、孔隙水压力、滑动带土应力以及滑坡体位移等进行实时监测,分析了各监测要素与大气降水的关系。通过大气降水和滑坡稳定性关系研究,初步确定了江西省滑坡灾害预报预警的降水量指标。监测试验结果表明,滑坡是可以预报的。滑坡体发生滑动的降水临界值试验及模拟结果与统计学分析有较好的一致性。 (5)揭示了地下水位变化与大气降水变化一致性特征。地下水位与滑坡稳定度呈负相关。试验表明,地下水位波动一般滞后于降水过程0.51天,每个降水过程对地下水位的影响因滑体本身而异,有的在5天之内即可消除,有的则延长至巧日,越接近地表,地下水位与降水变化在时间上一致性越强。 (6)揭示了滑坡体不同深度孔隙水压力值的变化特征。孔隙水压力是反应滑坡土体水分饱和程度的重要指标,研究表明,在一次降水过程中,随着降水量及强度的增加,孔隙水压力值增大,抗滑力下降,滑坡体稳定性减小。地下水位以下的孔隙水压力与降水过程及强度有很好的一致性;地下水位以上的包气带孔隙水压力在每个过程中有波动,峰值较降雨过程滞后02天,自3月至8月孔隙水压力逐渐下降,至8月中下旬达最低值,以后逐步回升,其变化趋势与蒸发蒸腾作用有关。 (7)揭示了滑坡土体应力变化与滑坡体位移的响应关系。应力监测是反映滑坡体是否发生蠕动的较好指标。试验结果表明,应力监测在反映滑坡体是否发生滑动时比孔隙水压力更为敏感。 (8)提出了植被覆盖对滑坡的影响主要取决于降水强度的观点。植被覆盖度高、生物量多和植被覆盖差、生物量低的中低山区都可能发生滑坡。森林植被对大气降水有截留作用,能减缓水蚀和雨蚀,但当降水强度超过50rnrn时,截留作用减小。同等地质环境条件下,植被覆盖率低,滑坡较易发生,当降水强度较大时,特别是达到诱发滑坡灾害发生的临界值时,由于植被根系分布深度小于浅层滑坡土体深度,植被对滑坡体的重力作用会加重滑坡的发生。但高森林覆盖区发生滑坡的雨量临界值大于覆盖率差的区域。 (9)建立了滑坡灾害预测模型,开发了基于W七b一GIS的滑坡灾害预报预警业务系统,并进行了业务试验。结果表明,2004年5次区域性暴雨过程均导致局地滑坡灾害,预报预警等级与滑坡灾害发生程度一致。关键词:暴雨,滑坡灾害,机理,预测方法,研究  还原水利论文DfsgB;g8@m#b

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【英文摘要】 For meeting the service needs of predicting and warning landslides triggered by extremely heavy rainfall, based on mechanism of landslide induced by torrential rainstorm and its predicting theory, by monitoring and experiment in eight trial grounds, the impacts of rainfall on underground water table, pore water pressure, soil stress and landslides stability are studied. The influence of vegetation coverage on landslide is discussed. With historic data, risk division is researched and the temporal-spatial distribution features of landslide induced by heavy rainfall are analyzed. Combining trail data and statistics method, the precipitation values used to predicting and warning landslides are given. Operational forecasting and warning system of landslide disasters triggered by heavy rainfall on Web-GIS is developed, which has been tested in conventional operation.(1) The temporal-spatial distribution features of landslide induced by heavy rainfall are revealed. Characteristics of Jiangxi...更多 provincial landslides can be described mainly as types of shallow layer. The structure of landslide is expressed mostly in form of integral movement. Landslides happened in hilly land are more than other conditions. Amount and volume of landslides in sharp slope are lager than that of terrain slope relatively and gently. Considering effects of height, large numbers of landslides appear in height between 100 to 400 meters above sea level. Most of landslides take place in raining season. A great of landslides are triggered by heavy rainfall, which takes a proportion of 87% in May to July and especially 70% in June. The times of landslide disasters happened in daily rainfall with 100 to 400mm are 70% on totals. Most landslide disasters occur nearly the same time with precipitation period and minority lags. Regions having 5 to 6 heavy rainfall days general in a year attribute to susceptibility areas of landslides.(2) Daily comprehensive rainfall index to forecast landslides are investigated. By analyzing data since 1960s, precipitation-inducing landslides not only relate to currently rainfall but also lie on previous raining procedure. The influence of daily precipitation on landslide can persist one to ten days. Declined coefficient is introduced into comprehensive rainfall model, which is used to calculate effective rainfall. Daily changes and function of evaportranspiration on the index are studied.(3) The dynamic process and mechanism of landsides triggered by extremely heavy rainfall are revealed. The function of precipitation on landslide is a dynamic process. When raining water impregnate into landslide mass, it can increase water content and volume weight of rock soil mass, intenerate soil, enhance rock soil capacity, and also becomes lubricant while penetrating into bedrock surface under weathering rock mass or layer cutting with water, which diminish anti-slide force and cause landslide. Superficial landslide in torrential rainfall are due to short time function of violent precipitation, in the case, landslide mass quickly arrive to saturation situation that lead to ground displacement sharply, as water penetrate promptly and make ascending of soil saturation degree and pore water pressure, reducing slope substance strength and ending with happening landslide, addressing above as superficial landslide mechanism.(4) Critical values of precipitation to forecast landslides are investgated, which provide bases for predicting and warning landslide disasters. Eight observation grounds in susceptibility areas in Jiangxi province are devised to monitoring changes of water table, pore water pressure, stress of gliding zone, and landslide mass movement. Based on observing data and historic records, the purpose is to study models of landslidesstability and search criterions for predicting or warning landslide disasters. By monitoring and experiment, it is proved that landslide hazards can be predicted. Critical rainfall value to induce landslide acquiring from field trial is in consonance with statistics results.(5) Changes of water tab  还原

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【中文关键词】 暴雨; 滑坡灾害; 机理; 预测方法; 研究
XZ;x2hw~0【英文关键词】 Heavy rainfall; Landslide hazard; Mechanism; Predicting method; Study水利论文,j+KO0Chg?,@

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TAG: 机理 灾害 魏丽 滑坡 郑有飞
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