本文選題：泥石流 + 松散堆積體�。� 參考：《成都理工大學(xué)》2017年碩士論文

【摘要】：四川汶川“5.12”大地震震后在地震重災(zāi)區(qū)引發(fā)了多種次生地震災(zāi)害,其中尤其以泥石流影響最為嚴(yán)重。地震中以及震后大量的崩塌、滑坡都會(huì)在溝道中形成大量松散堆積體的累積,這也為泥石流在爆發(fā)后運(yùn)移過程中規(guī)模的不斷擴(kuò)大提供了豐富的物質(zhì)條件。本文在資料查閱、野外現(xiàn)場(chǎng)勘察的基礎(chǔ)上,以震后溝道松散堆積體為研究對(duì)象,采用室內(nèi)水槽模擬實(shí)驗(yàn),對(duì)泥石流底部侵蝕作用的相關(guān)影響因素進(jìn)行研究。通過大量物理實(shí)驗(yàn),獲得泥石流對(duì)溝道底部侵蝕作用與初期泥流漿體濃度、溝道坡度及初始含水率等因素的關(guān)系,主要研究成果如下:(1)泥漿流經(jīng)鋪滿松散砂料的溝槽時(shí),可以形成挾帶大量顆粒并在前端有明顯陡立的龍頭,且龍頭速度遠(yuǎn)小于后續(xù)流體流速。這一現(xiàn)象隨坡度、泥漿濃度的改變而改變。當(dāng)坡度較大時(shí),泥漿沖刷作用明顯,流體前峰會(huì)有明顯隆起的龍頭,且龍頭內(nèi)固體顆粒含量較高;當(dāng)坡度較小,或泥漿濃度較大時(shí),泥流前峰不會(huì)形成龍頭,且前峰中幾乎不含固體顆粒。(2)實(shí)驗(yàn)過程中,泥漿入流初期,漿體動(dòng)能較大,在實(shí)驗(yàn)槽上部的松散堆積體中迅速?zèng)_蝕,被泥漿沖刷帶走的固體顆�；烊霛{體繼續(xù)向下運(yùn)動(dòng),進(jìn)而在后續(xù)運(yùn)移沖刷過程中表現(xiàn)為下切侵蝕。整個(gè)模式表現(xiàn)為逐漸侵蝕加劇,所形成的泥石流容重不斷增加。(3)漿體濃度、溝槽坡度可以影響泥石流的入滲能力和侵蝕速率。僅考慮漿體濃度的影響時(shí),隨著漿體濃度的增加,泥石流在溝道松散堆積物的入滲能力降低,侵蝕速率減小,侵蝕量也隨之減小;僅考慮坡度的影響時(shí),坡度不僅會(huì)影響泥石流起動(dòng)的臨界流量,也會(huì)顯著影響泥石流作用于溝床底部的侵蝕作用。坡度越大,漿體對(duì)松散堆積體的侵蝕速率越大,泥石流的后期規(guī)模也會(huì)越大。(4)除了漿體濃度、溝床坡度外,溝道松散堆積體的初始含水率也會(huì)顯著影響泥石流流經(jīng)溝道時(shí)的流動(dòng)性和入滲能力,從而影響泥石流的侵蝕速率,相對(duì)于含水率較高的松散堆積物,干性砂料更容易被漿體吸附并隨泥漿運(yùn)移;漿體內(nèi)的細(xì)小固體顆粒會(huì)進(jìn)入松散堆積體的原生骨架并與其結(jié)合形成級(jí)配較好的相對(duì)穩(wěn)固的堆積體,這會(huì)使泥漿的侵蝕能力降低。
[Abstract]:After the May 12 earthquake in Wenchuan, Sichuan Province, it caused many secondary earthquake disasters, especially debris flow. During and after the earthquake a large number of collapses and landslides will form a large number of loose accumulations in the channel which provides abundant material conditions for the continuous expansion of the scale of debris flow in the process of migration after the eruption. Based on the reference of data and field investigation, this paper takes the loose accumulation body of channel after earthquake as the research object, and uses the indoor flume simulation experiment to study the influence factors of debris flow bottom erosion. Through a large number of physical experiments, the relationship between the erosion of debris flow to the bottom of the channel and the initial mud slurry concentration, channel slope and initial moisture content is obtained. The main research results are as follows: 1) when the mud flows through the channel filled with loose sand, A large number of particles can be formed with a sharp front end, and the faucet velocity is much smaller than that of the subsequent fluid flow rate. This phenomenon changes with the change of slope and mud concentration. When the slope is high, the mud scour is obvious, and there is a clear bulging faucet at the pre-fluid summit, and the solid particle content in the tap is higher; when the slope is low or the mud concentration is high, the faucet does not form at the mudflow front peak. In the process of the experiment, the kinetic energy of the slurry is larger at the initial stage of the mud flow, and the slurry is rapidly eroded in the loose accumulations in the upper part of the experimental tank, and the mixed solid particles removed by the mud continue to move downward. And then in the course of subsequent migration erosion, it is shown as undercutting erosion. The whole model is characterized by gradually increasing erosion and increasing bulk density of debris flow. The slope of groove can affect the infiltration capacity and erosion rate of debris flow. Considering only the effect of slurry concentration, the infiltration ability of debris flow in the channel loose accumulation decreases, the erosion rate decreases, and the erosion amount decreases with the increase of slurry concentration. The slope will not only affect the critical flow of debris flow starting, but also affect the erosion of debris flow at the bottom of trench bed. The larger the slope, the larger the erosion rate of the slurry to the loose accumulation, and the larger the scale of debris flow in the later stage. The initial moisture content of the channel loose accumulation also significantly affects the fluidity and infiltration ability of debris flow through the channel, thus affecting the erosion rate of debris flow, relative to the loose accumulation with higher water content. Dry sand is more easily adsorbed by the slurry and transported with the slurry, and the fine solid particles in the slurry will enter the primary skeleton of the loose accumulation and combine with it to form a relatively stable accumulation with better gradation, which will reduce the erosion ability of the slurry.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P642.23

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