澜沧江上游杂多县城段泥石流形成条件与危险范围预测研究

发布时间：2018-05-23 21:06

本文选题：泥石流 + 形成条件　；参考：《长安大学》2015年硕士论文

【摘要】：研究区澜沧江上游干流—扎曲杂多县城段位于青藏高原腹地,在青藏高原持续隆升的影响下,断裂、褶皱发育强烈,新构造运动活跃,垂直差异性升降运动明显,沟谷发育,地形切割严重,冻融风化剥蚀作用强烈。研究区属高寒大陆性高原气候,降雨集中,雨强较高。致使区内扎曲两侧支沟泥石流极为易发,给当地居民生命财产和建筑设施造成严重威胁和损失,并严重破坏了区内生态环境。因此研究区内泥石流的形成条件、预测其危险范围并提出防治方案不仅能够为该地区的防灾减灾工作提供有效的理论依据,而且对其他地质环境类似地区的泥石流预测研究也具有参考借鉴意义。论文在野外调查的基础上,对泥石流进行分类并分析其形成条件:区内泥石流以暴雨型沟谷泥石流为主,大多为稀性中易发泥石流,多处于旺盛期;主要发育在流域面积小于5km2的“V”字型沟谷,平面形态多呈“漏斗状”,主沟纵坡值较大,两侧沟坡以陡坡为主,流域高差多在100~500m;物源以风化和节理发育的硬岩为主,通过岩石冻融实验发现随着冻融循环次数的增加,岩样的纵波波速、CT数和抗拉强度都呈减小的趋势,致使岩样的整体性变差、强度降低,不断破碎,形成松散堆积物,在重力作用和地表水的作用下,进入到泥石流沟道中,构成了泥石流的主要物源;大气降水和冰雪融水组成了泥石流的水动力条件,其中以降雨为主,冰雪融水作为区内泥石流水动力的一个重要组成部分,对区内泥石流的发育有重要影响。植被对泥石流的形成有抑制和促进的双重作用,但其影响是有限的。通过对研究区泥石流堆积扇形态的野外调查和遥感解译,总结其形状主要有四种:扇形、扫帚形、叠加形和舌形。利用MATLAB软件分析泥石流堆积范围与其影响因子的相关性认为,在地形地貌因子中流域面积和流域相对高差两个因子是泥石流堆积范围预测的关键因子;在物源因子中选择物源总储量代替参与运动的动储量,可以作为泥石流堆积范围预测的关键因子;在水动力因子方面,认为研究区现有泥石流堆积扇是在日最大降雨量21.7mm~37.9mm范围条件下,多年多次堆积形成的;最终在日最大降雨量21.7mm~37.9mm的前提条件下,选取流域面积、流域相对高差、泥石流沟内物源总储量三个作为预测因子,用研究区内29条泥石流沟的相关数据,通过多元回归分析,建立了研究区泥石流最大堆积长度和最大堆积宽度的预测模型,并用这29条沟的数据进行了自检,误差满足初步预测的精度要求。用研究区内另外5条典型泥石流沟数据对建立的模型进行了检验,分析了产生误差的原因,认为该模型预测产生的误差是客观的,也是合理的。说明该计算模型对研究区或与研究区流域环境地质背景相似的其他地区具有一定的适应性和可靠性,可以对这些区域的泥石流堆积范围进行初步的预测。最后对研究区典型泥石流—佐青寺泥石流提出了两种防治方案,运用模糊综合评判方法得出以拦为主,辅以排导的工程防治方案,即:拦砂坝+谷坊坝+单边防护堤+排导槽为较优防治方案。
[Abstract]:Located in the hinterland of the Qinghai Xizang Plateau, the main stream of the upper reaches of the Lancang River in the upper reaches of the Qinghai Tibet Plateau, under the influence of the sustained uplift of the Qinghai Tibet Plateau, the faults and folds develop strongly, the movement of the neotectonic movement is active, the vertical differential movement is obvious, the valley is developed, the terrain is cut seriously and the freezing thawing weathering denudation is strong. The study area belongs to the high cold continental plateau. The climate, the concentration of rainfall and the high intensity of the rain have caused the debris flow of the two sides of the district to be very easy to occur, causing serious threat and loss to the local residents' life, property and building facilities, and seriously destroying the ecological environment in the area. Therefore, the formation conditions of the debris flow in the study area, the prediction of the danger range and the prevention scheme not only can be used for this area. The work of disaster prevention and reduction in the area provides an effective theoretical basis, and is also of reference significance to the debris flow prediction research in other geological environment similar areas. Based on the field investigation, the paper classifies the debris flow and analyzes its formation conditions: the debris flow in the area is mainly the storm and ravine debris flow, most of which are easy to occur in the rarefying. Debris flow is mostly in exuberant period, mainly developed in "V" gully with area less than 5km2, the plane shape is mostly "funnel shape", the main ditch vertical slope is larger, the slope of the two sides is steep, the valley height is more in 100~500m, the source is mainly hard rock with weathering and joint development, and the freezing thawing experiment found with freezing thawing cycle times. With the increase of the number, the longitudinal wave velocity, CT number and tensile strength of the rock samples are decreasing, resulting in the deterioration of the integrity of the rock samples, the decrease of the strength, the continuous fragmentation and the formation of loose deposits. Under the action of gravity and surface water, it enters into the debris flow channel and forms the main source of the mud and rock flow; the atmospheric precipitation and ice snow melt constitute mud. The hydrodynamic conditions of the rock flow are mainly rainfall, and ice and snow melt water is an important part of the hydrodynamic force of the debris flow in the region. It has an important influence on the development of debris flow in the region. The vegetation has a double effect on the formation of debris flow, but its influence is limited. There are four main forms of the survey and remote sensing interpretation. The main shapes are the fan shape, the broom shape, the superposition shape and the tongue shape. The MATLAB software is used to analyze the correlation between the accumulation range of debris flow and its influence factors. It is considered that the two factors of the basin area and the relative height difference in the watershed are the key factors of the debris flow accumulation range prediction. The total reserves of the selected material sources in the subregion can replace the active reserves participating in the movement, which can be used as the key factor for the prediction of debris flow accumulation range. In the aspect of hydrodynamic factors, it is considered that the existing debris flow fan in the study area is formed by many years of heap under the 21.7mm~37.9mm range of the daily maximum rainfall, and the maximum daily rainfall is 21.7mm~37.9mm. Under the precondition, the area of the basin, the relative height of the basin and the total reserves of the debris in the debris flow gully are three as the prediction factors. The prediction model of the maximum accumulation length and the maximum heap width of the debris flow in the study area is established by multiple regression analysis, and the data of the 29 gully are used. The error satisfies the precision requirement of the preliminary prediction. 5 other typical debris flow trench data in the study area are used to test the established model, and the cause of the error is analyzed. It is considered that the prediction error of the model is objective and reasonable. The other areas with similar scenery have certain adaptability and reliability, and the debris flow accumulation range of these areas can be preliminarily predicted. In the end, two prevention and control schemes are put forward for the typical debris flow of the study area, the debris flow of the Zuo Qing temple. Sand control dam + Valley Dam + unilateral embankment + drainage channel is a better control plan.
【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】：P642.23

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