選題：泥石流　視角：平衡坡度　引自：《成都理工大學(xué)》2017年碩士論文

【摘要】：泥石流是我國(guó)西南山區(qū)常見(jiàn)的地質(zhì)災(zāi)害之一,具有爆發(fā)突然、運(yùn)動(dòng)快速、能量巨大、沖擊力強(qiáng)、破壞性大等特點(diǎn),沖和淤是其主要危害。泥石流的平衡坡度是指泥石流在運(yùn)動(dòng)過(guò)程中,泥石流的表面流速在溝床內(nèi)達(dá)到一個(gè)定值,泥石流對(duì)溝床的影響為不沖不淤狀態(tài)時(shí)的溝床坡度。泥石流排導(dǎo)槽是泥石流災(zāi)害治理的主要工程手段之一,排導(dǎo)槽的坡度是排導(dǎo)槽設(shè)計(jì)的重要指標(biāo)。排導(dǎo)槽的設(shè)計(jì)坡度就是泥石流的平衡坡度:當(dāng)排導(dǎo)槽的坡度大于泥石流的平衡坡度時(shí),泥石流對(duì)排導(dǎo)槽的影響為沖刷,將縮短排導(dǎo)槽的使用壽命;當(dāng)排導(dǎo)槽的坡度小于泥石流的平衡坡度時(shí),泥石流將在排導(dǎo)槽內(nèi)淤積,達(dá)不到排導(dǎo)效果。所以,進(jìn)行泥石流平衡坡度的研究將對(duì)泥石流排導(dǎo)槽坡度的設(shè)計(jì)具有指導(dǎo)作用。泥石流的平均流速是對(duì)泥石流評(píng)估和防治最重要的參數(shù)之一。在野外觀測(cè)中,泥石流的平均流速難以獲得,而表面流速的獲得相對(duì)容易,通過(guò)兩者的關(guān)系可以將表面流速換算成平均流速。所以,進(jìn)行泥石流平均流速與表面流速之比的研究也很重要。前人對(duì)泥石流平衡坡度和平均流速與表面流速之比的研究,考慮的影響因素主要集中在泥石流的性質(zhì)或運(yùn)動(dòng)特征上,忽略了泥石流溝床對(duì)泥石流平衡坡度及平均流速與表面流速之比的影響,研究成果較難滿足復(fù)雜多變的野外情況。針對(duì)前人研究的不足之處,本文結(jié)合理論分析、選取研究的重要參數(shù)、采用控制變量法進(jìn)行泥石流平衡坡度和平均流速與表面流速之比的室內(nèi)水槽實(shí)驗(yàn)研究,得到以下結(jié)論:(1)泥石流屈服應(yīng)力(τ)、流深(H)和容重(γ)是影響泥石流平衡坡度的重要參數(shù)。無(wú)量綱化的屈服應(yīng)力(τ*)包括泥石流的屈服應(yīng)力、泥石流流深和容重,τ*=τ/(γgH)。屈服應(yīng)力τ*越大,粘性越大,內(nèi)部阻力越大,泥石流的平衡坡度越大;反之,屈服應(yīng)力τ*越小,粘性越小,內(nèi)部阻力越小,泥石流的平衡坡度越小。(2)泥石流運(yùn)動(dòng)溝床粗糙率是影響泥石流平衡坡度的重要參數(shù)之一,泥石流運(yùn)動(dòng)的底床粗糙率對(duì)流動(dòng)中的泥石流底部產(chǎn)生阻力,泥石流運(yùn)動(dòng)的底床粗糙率越大,需要克服泥石流運(yùn)動(dòng)的阻力越大,所需要的驅(qū)動(dòng)力越大,所需的平衡坡度也就越大;相反,泥石流運(yùn)動(dòng)的底床粗糙率越小,需要克服泥石流運(yùn)動(dòng)的阻力越小,所需要的驅(qū)動(dòng)力越小,所需的平衡坡度也就越小。(3)通過(guò)控制變量法,實(shí)驗(yàn)研究得出泥石流運(yùn)動(dòng)的底床粗糙率(n)和無(wú)量綱的屈服應(yīng)力(τ*)與泥石流平衡坡度的關(guān)系式為tana=0.0093e18.39n+30τ/(γgH)。(4)泥石流屈服應(yīng)力(τ)、容重(γ)和流深(H)是泥石流平均流速與表面流速之比的重要參數(shù)。無(wú)量綱化后的屈服應(yīng)力(τ*)包括泥石流的屈服應(yīng)力、容重和流深,τ*=τ/(γgH)。屈服應(yīng)力τ*越大,粘性越大,內(nèi)部粘性阻力越大,平均流速與表面流速的比值就越小;反之,屈服應(yīng)力τ*越小,粘性越小,內(nèi)部粘性阻力越小,平均流速與表面流速的比值就越大。(5)泥石流運(yùn)動(dòng)的底床粗糙率是泥石流平均流速與表面流速之比的重要參數(shù)之一。泥石流運(yùn)動(dòng)的底床粗糙率越大,阻力越大,對(duì)底部速度影響區(qū)域越大,平均流速越小,平均流速與表面流速之比也就越小;相反,泥石流運(yùn)動(dòng)的底床粗糙率越小,阻力越小,對(duì)底部速度影響區(qū)域越小,平均流速越大,平均流速與表面流速之比也就越大。(6)通過(guò)控制變量法,實(shí)驗(yàn)研究得出泥石流運(yùn)動(dòng)的底床粗糙率(n)和無(wú)量綱的屈服應(yīng)力(τ*)與泥石流的平均流速與表面流速之比的關(guān)系式為Vm/Vs=(17.17n2-3.41n+0.6)[τ/(γgH)]-0.07。
[Abstract]:Debris flow is one of the common geological disasters in the southwest mountainous area, with a sudden movement, fast, powerful, strong impact, destructive, impulse and silt is the main hazard. Equilibrium slope debris flow refers to debris flow in the process of movement, the surface debris flow velocity reaches a fixed value in the ditch in the bed, on the influence of debris flow gully bed for the silt stable state of the slope of the gully bed. Debris flow channel is one of the main means of debris flow control, drainage trough slope drainage is an important indicator of groove design. Design of slope slope balance slot is: when the balance of debris flow slope drainage groove slope is greater than the impact of debris flow, debris flow drainage groove for erosion, will shorten the service life of the drainage groove; when the equilibrium slope drainage groove slope is less than the debris flow, debris flow in the drainage groove within the deposit, not up To the drainage effect. Therefore, the research of debris flow equilibrium slope will play a guiding role in the design of debris flow drainage groove slope. The average velocity of debris flow is one of the most important evaluation and prevention of debris flow parameters. In the field observation, the average velocity of debris flow is difficult to obtain, and the surface velocity is relatively easy to obtain, through both the relationship can be converted into the mean velocity of surface flow velocity. So, it's also important to study on the debris flow average velocity and surface velocity ratio. The previous study on debris flow equilibrium slope and the mean velocity and surface velocity ratio, the affecting factors are mainly concentrated in nature or movement characteristics of debris flow, ignoring the debris flow the influence of debris flow equilibrium slope and mean velocity and surface velocity ratio. The research results are difficult to meet the complex field situation. According to the former research not The shortage of this paper combines the theory analysis, the important parameters selection, the flume experiments were carried out to study the debris flow balance slope and the mean velocity and surface velocity ratio of the control variable method, we get the following conclusions: (1) the debris flow yield stress (tau), flow depth (H) and bulk density (R) is an important influence the parameters of debris flow equilibrium slope. No yield dimensionless stress (t *) including debris flow yield stress, flow depth of debris flow and bulk density, t / R * = (gamma gH). The yield stress is greater the greater the *, viscosity, the greater the internal resistance of debris flow, the greater the degree of balance of slope on the other hand, the yield stress; t * is smaller, the smaller the viscosity, the internal resistance is small, the balance of slope of debris is small. (2) the debris flow gully bed roughness is one of the important parameters of debris flow equilibrium slope, debris flow bed roughness of debris flow in the bottom of the flow resistance, debris flow the 搴曞簥綺楃硻鐜囪秺澶，

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