汶川地震映秀岩浆岩地区坡面型泥石流成因模式及运动特征研究

发布时间：2018-07-29 17:28

【摘要】：研究区地处龙门山中段,山高谷深、岸坡陡峭,且地质构造复杂,新构造运动强烈。大量分布着花岗岩、花岗闪长岩等高强度岩石,这些岩石裂隙发育,岩体破碎,在遭受强烈震动以后,引发了不同规模的崩塌和滑坡,大量崩滑堆积体堆积在斜坡的不同部位,改变了斜坡的微地貌特征,影响震后斜坡的汇水条件,导致研究区形成了多种成因模式和运动特征不尽相同的坡面型泥石流。给灾区人民的生命财产和交通安全造成严重的影响。因此,开展对震后坡面型泥石流的研究,对减灾防灾有重要意义。论文取得的成果及结论如下:(1)、地震以后坡面型泥石流的活动增强,临界降雨量降低,表现出明显的高频性、群发性和类型多样性,具有突发性强、破坏性大、季节性强的特点。(2)、根据物源的类型和物源堆积状况的不同,将研究区的坡面型泥石流分为以下7类:1)、高位滑坡堆积体-揭底-侧蚀型:①、高位滑坡堆积体以中、小型滑坡堆积体为主,堆积位置较高。②、沟道纵比降相对较大,呈“陡-缓-陡”的阶梯状。③、泥石流运动速度快、冲击力大、破坏性强、运移距离远。④、侵蚀方式为:揭底侵蚀+侧向侵蚀。2)、大型滑坡堆积体-冲切-溯源侵蚀型:①、滑坡堆积体大多分布在坡脚处,多为厚层或巨厚层堆积体。②、整个滑坡堆积体稳定性较好,浅表层固体物质松散,稳定性较差。③、泥石流的动能较小,运动速度较低。④、侵蚀方式为:拉槽冲切+溯源侵蚀。3)、坡脚崩塌堆积体侵蚀型:在暴雨作用下,崩塌堆积体浅表松散物质呈片状启动。泥石流流速较慢,侵蚀能力较弱,沟道宽且浅。4)、高位崩塌堆积体侵蚀型:崩塌堆积体堆积部位较高,以中、小型堆积体为主,稳定性较差。物源具有一定的隐蔽性,流体运动速度快、破坏力强、危害性大。5)、沟内高位崩塌堆积体侵蚀型:泥石流具有间歇性期,在非暴雨期间,固体物质累积在沟道高处缓坡平台处;在暴雨期间,坡面径流冲刷松散固体物质形成泥石流。泥石流运动速度快,破坏力强,规模较小,爆发频率高。6)、滑坡型坡面型泥石流:①、多为小型浅层溜滑。②、滑坡体的位能是泥石流转化过程中主要动力来源。③、滑坡转化形成为泥石流是一个连续快速的过程,中间没有间断。④、流体运动过程中运动阻力较大。7)、崩塌型坡面型泥石流:可以分为两类:①、崩塌体直接转化为坡面型泥石流,过程如下:岩体崩塌撞击碎屑化流动堆积。②、崩塌体运动过程中扰动堆积体形成泥石流,过程如下:崩塌碰撞侵蚀流动堆积。③、物源多为震裂岩体,没有明显的汇水区域、流体容重大、规模较小、沟道细长,纵比降大、运动速度快。(3)、本文建立了以立方体为稀性坡面型泥石流粗颗粒的基本模型,提出了立方体模型的滑移、翻转(包括绕边翻转、绕支点翻转及嵌固绕边翻转)等启动方式。并推导得出了粗颗粒启动平均流速公式,采用陈奇伯的实验数据加以验证,计算结果较吻合。(4)、采用能量守恒定理和动量守恒定理,讨论不同质量的粗颗粒之间的碰撞过程,并以此分析流体运动过程中粗颗粒的运动特征。(5)、结合水力学基本原理和粗颗粒启动条件研究内容,探讨了泥石流粗颗粒启动条件与降雨强度之间的关系,为坡面型泥石流的监测提供一定的理论基础。
[Abstract]:The study area is located in the middle section of the Longmen mountain. Yamadaka Tani is deep, the bank slope is steep, and the geological structure is complex and the new tectonic movement is strong. A large number of high strength rocks, such as granite and granodiorite, are distributed in large quantities. These rocks are fractured and rock masses are broken. After the strong vibration, different scales of landslides and landslides are triggered, and a large number of landslide deposits are stacked in slanting. The different parts of the slope change the microgeomorphic features of the slope and influence the water confluence of the post - earthquake slope, which leads to the formation of a variety of genetic patterns and different slope type debris flows in the study area. The results and conclusions obtained in this paper are as follows: (1) after the earthquake, the activities of the slope debris flow are enhanced and the critical rainfall is reduced, showing obvious high frequency, group and type diversity, with sudden strong, destructive and seasonally strong characteristics. (2) according to the type of source and the accumulation of material sources In the same way, the slope debris flow in the study area is divided into 7 categories: 1), the high landslide accumulation body and the bottom side erosion type: (1) the high landslide accumulation body is mainly the small landslides accumulation body, and the accumulation position is high. The erosion mode is: exposure erosion + lateral erosion.2), large landslide accumulation - scouring and traceability erosion type: (1) most of the landslide deposits are distributed at the foot of the slope, mostly thick layer or thick layer accumulation body. 2. The stability of the whole landslide accumulation is good, the shallow surface solid material is loose and the stability is poor. The movement speed is low. (4) the erosion mode is the erosion pattern of the slotting and the traceability erosion.3) and the slope foot collapse accumulation. Under the action of the rainstorm, the shallow surface loose material of the collapse accumulation is flaky. The debris flow velocity is slow, the erosion ability is weak, the channel wide and the shallow.4), the high collapse accumulation body erosion type: the accumulation part of the collapse accumulation body is higher in the middle, The small accumulation body is mainly, the stability is poor. The source has a certain concealment, the fluid movement speed is fast, the destructive force is strong, the dangerous.5), the debris flow has the intermittent period, during the non rainstorm, the solid substance accumulates in the high slope platform of the channel height, and the sloping runoff scour loose solid during the rainstorm. Debris flow is formed by debris flow. Debris flow has fast speed, strong destructive force, small scale, high frequency of.6), and landslide type slope debris flow: (1) small and shallow skating. (2) the potential energy of the landslide body is the main source of power in the process of debris flow transformation. The collapse type slope type debris flow can be divided into two types: (1) the collapse body is divided into two types: (1) the collapse body is transformed directly into the slope type debris flow, and the process is as follows: rock mass collapse and debris flow accumulation. The main source is the rock mass, and there is no obvious area of the rock mass, there is no obvious water area, the fluid volume is important, the size is small, the channel is slender, the longitudinal ratio decreases and the movement speed is fast. (3) the basic model of the coarse particles with the cube as the lean slope is established in this paper, and the slip of the cube model is put forward, including the reversal of the winding, the reversal of the branch point and the embedding. The formula of starting average velocity of coarse particles is derived, and the formula of average velocity of starting of coarse particles is derived. The results are verified by Chen Qibo's experimental data. (4) the energy conservation and momentum conservation theorems are used to discuss the collision process between coarse particles of different mass and to analyze the transport of coarse particles in the process of fluid motion. (5) the relationship between the starting condition of the coarse particles and the rainfall intensity is discussed in accordance with the basic principle of hydraulics and the starting condition of coarse particles, which provides a theoretical basis for the monitoring of the sloping debris flow.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.23

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