基于物质组成和冲击特性的泥石流冲击力研究

发布时间：2018-12-28 18:51

【摘要】：目前各国泥石流学者相继发展了各类泥石流模型,使泥石流机理的研究取得了积极进展。但迄今仍没有能使国内外同行所接受的通用的泥石流模型,因此,泥石流机理的研究仍然是今后相当长一段时期内泥石流研究的重点和难点。本文针对泥石流冲击力进行了研究,采用固液两相流理论、非牛顿流体力学、泥沙运动力学泥石流冲击力进行研究,主要从泥石流固相比、泥石流级配条件下固相物质粒径、泥石流容重、泥石流粘度以及泥石流流速几个方面入手,结合泥石流现场观测数据得到泥石流冲击力计算新公式,并以室内模型试验结果和现场观测结果对该式进行实用性修正,得到泥石流冲击力计算新公式。(1)根据水石流、稀性泥石流和粘性泥石流的沉积特性,并且粘性泥石流流体中的固相物质呈逆序结构,分析了对泥石流容重的影响,根据现有的泥石流实验研究数据分析分别得出与固相比、级配条件下固相颗等效粒径以及浆体粘度有关的水石流、稀性泥石流、粘性泥石流的容重计算公式,并且与现有的经典泥石流容重计算公式进行对比分析,得出经典泥石流容重计算值式只考虑了泥石流的固相物质容重及固相比,但未考虑泥石流粘度及固相颗粒级配对泥石流容重的影响。(2)对水石流、稀性泥石流和粘性泥石流的流速计算方法分析,得出相应的流速计算公式,并且与现有的经典泥石流流速计算公式进行对比分析得出:本文的计算结果更贴近实验结果,而流速经典计算公式同常采用的是平均流速,实际泥石流的流速在流通区应该随着时间的增长而变化,并且多数情况下只考虑了泥石流平均流深和泥石流沟床比降。(3)通过对小波消噪方法进行了归纳介绍,本文采用MATLAB中的sym函数分析进行频频分析。泥石流冲击力是一个非均匀稳定的信号,水石流冲击力信号降噪图可以看出水石流的整个冲击过程比较连续,无明波峰,而稀性泥石流冲击过程有波峰的出现,从频谱分析来看,能量主要集中在低频部分,即d7频段和d8频段部分。粘性泥石流冲击过程波峰明显,从频谱分析来看,粘性泥石流冲击力低频部分仍是能量主要部分,并且包含了部分中低频段,即d5频段、d6频段、d7频段和d8频段,说明泥石流冲击过程虽然是一个瞬时过程,但是冲击力的变化比水石流和稀性泥石流的变化更为复杂。(4)水石流主要存在紊动应力和颗粒间碰撞摩擦产生的作用力,属于两相流模型;稀性泥石流与水石流相似,存在紊动应力和粒间作用力,属于结构两相流模型;粘性泥石流根据龙头压胀理论,将粘性泥石流视为可压缩流体从而建立连续方程进行求解,最终分别得出了与泥石流固相比、级配条件下固相颗粒等效粒径、粘度、容重有关的水石流、稀性泥石流和粘性泥石流的冲击力计算方法。(5)通过对比分析,水石流、稀性泥石流和粘性泥石流较计算值普遍比其他公式和实测值高,其原因分别是原因在于实验条件下颗粒的粒径相差不大,而现实中水石流粒径相差较大,并且水石流流体动能较大;稀性泥石流原因在于实验条件下粘度是由化学原料实现而缺失黏粒,黏粒缺失必然造成泥石流浆体容重变化,实际稀性泥石流容重比实验条件下的容重大,粘性泥石流原因在于粘性泥石流运动整体性较强,其粘度影响不可忽略,并且细黏粒含量较多,自身惯性力大,紊动应力小,运动速度也快,因此动能大,导致粘性泥石流冲击力很大。
[Abstract]:At present, various debris flow models have been developed by the country's debris flow scholars, so that the research of the debris flow mechanism has made positive progress. However, there is still no general debris flow model accepted by the domestic and foreign counterparts so far. Therefore, the research on the mechanism of debris flow is still the focus and difficulty of the study of debris flow in a long period of time. Based on the research of the impact force of the debris flow, this paper studies the impact force of the debris flow by using the two-phase flow theory, the non-Newtonian fluid mechanics and the mud-sand movement, mainly compared with the debris flow, the particle size of the solid phase and the volume weight of the debris flow under the condition of the debris flow. Based on the flow velocity of the debris flow and the flow velocity of the debris flow, a new formula for calculating the impact force of the debris flow is obtained by combining the field observation data of the debris flow, and the practical correction is carried out on the type by using the indoor model test result and the on-site observation result, so as to obtain a new formula for calculating the impact force of the debris flow. (1) according to the sedimentation characteristics of the water, the thin-flow and the viscous debris flow, and the solid-phase substance in the viscous debris flow fluid is in a reverse order structure, the influence on the volume weight of the debris flow is analyzed, The calculation formula of the volume weight of the water volume, the dilute debris flow and the viscous debris flow related to the solid phase equivalent particle size and the viscosity of the slurry body under the grading condition is compared and analyzed with the existing calculation formula of the volume weight of the classical debris flow, It is concluded that the calculation of the volume weight of the classical debris flow only takes into account the volume weight and the solid phase of the solid phase of the debris flow, but the influence of the viscosity of the debris flow and the volume weight of the solid-phase particle-level matching debris flow is not considered. (2) The calculation method of the flow velocity of the water, thin-flow and viscous debris flow is analyzed, the corresponding flow velocity calculation formula is obtained, and compared with the existing calculation formula of the flow velocity of the classical debris flow, the calculation results of this paper are closer to the experimental results. The classical calculation formula of flow velocity is the same as the average flow rate, and the flow velocity of the actual debris flow should change with the increase of time in the circulation area, and in most cases only the average flow depth of the debris flow and the ratio of the flow rate of the debris flow are considered. (3) The method of wavelet de-noising is introduced, and the frequency analysis is carried out by using the sym function analysis in MATLAB. The impact force of the debris flow is a non-uniform and stable signal, and the noise reduction diagram of the impact force of the water hammer can be seen that the whole impact process of the water flow is continuous and has no bright peak, and the impact process of the dilute debris flow has the appearance of a wave crest, and the energy is mainly concentrated in the low frequency part from the spectrum analysis. i.e. the d7 frequency band and the d8 frequency band portion. The peak of the viscous debris flow impact process is obvious, and from the spectrum analysis, the low frequency part of the viscous debris flow impact force is still the main energy part, and the low-frequency section of the section is included, that is, the d5 frequency band, the d6 frequency band, the d7 frequency band and the d8 frequency band, Although the impact process of the debris flow is a transient process, the change of the impact force is more complex than that of the water-and lean-flow. (4) the hydrodynamic stress and the acting force generated by the collision friction between the particles mainly exist in the water flow, and belong to the two-phase flow model; the dilute debris flow is similar to that of the water, and is a two-phase flow model of the structure; and the viscous debris flow is based on the tap pressure expansion theory, The viscous debris flow is considered to be a compressible fluid, and a continuous equation is established for solving, and finally, the method for calculating the impact force of the solid-phase particle equivalent particle size, the viscosity and the volume weight of the solid-phase particles under the gradation conditions is obtained respectively, and the calculation method of the impact force of the thin-flow and the viscous debris flow is obtained. (5) Compared with other formulas and measured values, the reason is that the particle size of the particles is not large in the experimental conditions, and the particle size of the water in the reality is relatively large, and the reason of the dilute debris flow is that the viscosity under the experimental conditions is realized by the chemical raw materials, The reason of the viscous debris flow is the strong integrity of the viscous debris flow, the influence of its viscosity is not negligible, and the content of the fine particles is large, the self-inertia force is large, the dynamic stress is small, the moving speed is also fast, and therefore, the kinetic energy is large, resulting in a large impact force of the viscous debris flow.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.23

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