冰碛补给型泥石流启动试验研究

发布时间：2018-06-18 02:52

  本文选题：泥石流启动试验 + 冰碛土　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：本次研究以发育在贡嘎山东坡磨西河流域内冰碛补给型泥石流为原型,应用地质学和水力学的相关理论方法,采用野外调查、室内模拟试验、现场试验及数理统计分析等手段,在深入调查区域内泥石流地形地貌特征、地质构造特征、水文气象特征和冰川活动特征的基础上,完成了对相关试验方案的设计,并先后在四川大学水力学与山区河流开发保护国家重点试验室和贡嘎山东坡磨西河流域内开展了冰碛土启动形成泥石流的室内水槽试验和野外现场试验。通过理论分析和试验相结合,初步查明了高寒山区冰碛补给型泥石流物源汇集模式及其对泥石流行程的影响,通过对比分析不同试验条件下冰碛土启动形成泥石流所需的水力学参数特征差异现象,揭示了冰碛土在不同径流条件作用下启动行程泥石流的过程机制,深入研究了沟道径流对冰碛土的入渗、侵蚀及启动的连续过程,初步建立了基于泥石流的启动时间(y)与物源粗化过程持续时间(x)关系的数学模型,为高寒山区冰碛补给型泥石流的形成机理认识及预测预报提供了科学依据。研究主要取得了以下一些认识:1.冰碛补给型泥石流沟道内物源汇集模式:是重力作用汇集、支沟泥石流汇集和冻融作用汇集的综合,并以后两种汇集方式为主。冻融作用汇集模式包括3类循环冻融方式:循环式冻融汇集、季节性冻融汇集、坡向式冻融汇集。循环冻融作用汇集模式维持了沟道内冰碛土物源“非粗化层”的特点,使冰碛补给型泥石流具有与一般水力类泥石流不同的启动机制。2.冰碛补给型泥石流的启动过程:物源表层粗化过程沟道径流形成过程粗颗粒启动过程。沟道径流形成过程是物源表层遭受深度侵蚀破坏的结果,为粗颗粒的启动提供有利条件。粗颗粒启动标志着泥石流启动,以侧向侵蚀和垂向掏蚀的方式侵蚀物源来不断增强泥石流流量。3.冰碛土物源的大规模侵蚀破坏,是作为粗颗粒固体物质基底的细颗粒物质被掏空的结果。径流在粗颗粒组成的径流通道内汇流后侵蚀能力更强,导致了细颗粒物质优先启动,而未启动的粗颗粒暴露程度增加并失去基底支撑并随着持续径流冲刷而启动。4.泥石流对物源的侵蚀过程中流体水深面和侵蚀面在纵截面上一直维持着波状形态,两者波峰和波谷的位置并不是固定,却表现出形态几乎一致的协同变化的特点。对沟床的侵蚀主要集中在渗透强度高的波谷,整个过程表现为“先渗透先侵蚀”的特征。随着泥石流侵蚀强度的增加,水深面和侵蚀面的波高和波长也加大。5.冰碛补给型泥石流的启动时间(y)与物源粗化过程持续时间(x)数学关系模型:y=3.5x。这表明虽然物源颗粒分布情况和泥石流启动水动力条件不同,但是在某一次特定启动条件下,泥石流启动时间始终受物源粗化阶段持续时间的控制,两者之间存在着一定的函数关系。
[Abstract]:In this study, based on the development of moraine recharge debris flow in the Moxi River basin on the east slope of Gongga Mountain, using the relevant theoretical methods of geology and hydraulics, field investigation, indoor simulation test, field test and mathematical statistical analysis, etc. On the basis of in-depth investigation of the landform and geomorphological characteristics, geological structure characteristics, hydrometeorological characteristics and glacier activity characteristics of debris flow in the region, the design of the relevant test scheme has been completed. In the state key laboratory of hydraulics and river development and protection in Sichuan University and in the Moxi River basin on the east slope of Gongga Mountain, the indoor flume test and field test on the initiation of debris flow by moraine soil were carried out. Through the combination of theoretical analysis and experiment, this paper preliminarily found out the collecting model of debris flow source of moraine recharge type in alpine mountainous area and its influence on the debris flow travel. By comparing and analyzing the characteristics of hydraulic parameters of debris flow caused by the initiation of moraine soil under different experimental conditions, this paper reveals the mechanism of the process of starting debris flow under different runoff conditions. The continuous process of infiltration, erosion and start-up of moraine soil by channel runoff is studied in depth. The mathematical model of the relationship between the starting time of debris flow and the duration of material source coarsening process is established preliminarily. It provides a scientific basis for the understanding of formation mechanism and prediction of the recharge debris flow in alpine mountainous areas. The research mainly obtained the following understanding: 1. The collection model of material source in debris flow channel of moraine recharge type is the synthesis of gravity action collection, branch gully debris flow collection and freeze-thawing process collection, and the latter two kinds of collecting modes are the main. There are three types of freezing and thawing patterns: cyclic freezing and thawing, seasonal freezing and thawing, slope freezing and thawing. The circulation freeze-thaw gathering model maintains the characteristics of the "non-coarse layer" of the source of moraine soil in the channel, which makes the recharge debris flow of the moraine have a different starting mechanism from that of the general hydrodynamic debris flow. The starting process of moraine recharge debris flow is: the coarsening process of the surface layer of the material source, the course of channel runoff formation and the starting process of coarse particles. The formation process of channel runoff is the result of deep erosion on the surface of the material source, which provides favorable conditions for the initiation of coarse particles. The start of coarse particles marks the start of debris flow, which increases the debris flow by lateral erosion and vertical erosion. The massive erosion of moraine soil is the result of the hollowing out of fine granular material as the substrate of coarse granular solid material. The erosion ability of runoff in the runoff channel composed of coarse particles is stronger, which leads to the primacy of fine particle material, while the exposure degree of coarse particles that is not started increases and loses the base support and starts up with continuous runoff scouring. In the process of debris flow erosion to the source, the water depth and erosion surface of the fluid always maintain the wave shape on the longitudinal section. The position of the wave peak and trough is not fixed, but they show the characteristics of almost consistent and synergistic change. The erosion of trench bed is mainly concentrated in the trough with high permeability, and the whole process is characterized by "infiltration first and erosion first". With the increase of debris flow erosion intensity, the wave height and wavelength of water depth and erosion surface also increase. The relation between the starting time of moraine recharge debris flow (y) and the duration of material source coarsening process (x) is: y = 3.5x. This indicates that although the distribution of the source particles is different from the hydrodynamic conditions of the debris flow starting, the starting time of the debris flow is always controlled by the duration of the material source coarsening stage under a certain starting condition. There is a certain functional relationship between the two.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.23
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本文编号：2033696