本文關(guān)鍵詞： Vajont滑坡 DDA 穩(wěn)定性 高速運(yùn)動(dòng) 強(qiáng)度衰減　出處：《西南交通大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：大型滑坡,由于體積龐大,能以極高的運(yùn)動(dòng)速度向前滑移,通常會(huì)給沿途民居聚居地帶來(lái)毀滅性的災(zāi)難。發(fā)生在意大利的Vajont滑坡,是大型高速滑坡中的典型,引起了大型高速滑坡的研究熱潮。Vajont滑坡從開始潰滑到完全停積,歷時(shí)不足1分鐘,最大滑移速度達(dá)到了驚人的20m/s～30m/s,沖向水庫(kù)的巖石滑體激起了約平均100m高的涌浪,淹沒(méi)了下游五個(gè)村鎮(zhèn),2000多人因?yàn)榇舜螢?zāi)難失去了生命。目前針對(duì)Vajont滑坡的數(shù)值方法研究中,存在巖體參數(shù)取值不統(tǒng)一的問(wèn)題。另外,滑帶摩阻力降低被認(rèn)為是導(dǎo)致滑坡高速運(yùn)動(dòng)的原因,現(xiàn)階段研究多為探討滑帶強(qiáng)度衰減對(duì)滑坡運(yùn)動(dòng)能力的影響,而對(duì)于滑體強(qiáng)度衰減引起滑坡運(yùn)動(dòng)能力改變的研究較為缺乏。本文以Vajont滑坡為例,針對(duì)上述問(wèn)題,利用DDA方法分析了 Vajont滑坡在穩(wěn)定階段及運(yùn)動(dòng)階段的特征,根據(jù)滑坡特征反演探討了強(qiáng)度衰減對(duì)滑坡運(yùn)動(dòng)能力的影響,得出如下結(jié)論:(1)基于位移突變準(zhǔn)則建立了一種求解斜坡臨界態(tài)強(qiáng)度的方法,經(jīng)與傳統(tǒng)強(qiáng)度折減法驗(yàn)證,證實(shí)了其可靠性。具體在本文計(jì)算中,即在程序中每隔固定步數(shù)對(duì)滑面初始強(qiáng)度自動(dòng)進(jìn)行一次折減,當(dāng)斜坡特征點(diǎn)位移發(fā)生突變時(shí),對(duì)應(yīng)的強(qiáng)度即為臨界強(qiáng)度。(2)節(jié)理巖體摩擦角、滑面粘聚力和靜水位高度等對(duì)斜坡穩(wěn)定狀態(tài)的影響較大。節(jié)理巖體摩擦角每升高5°,維持斜坡穩(wěn)定的滑面臨界摩擦角則相應(yīng)減小0.5°;當(dāng)水庫(kù)水位升高至計(jì)劃最高蓄水高度時(shí),斜坡的安全系數(shù)約降低了 11.9%,由于降雨等導(dǎo)致斜坡內(nèi)部水位線非水平分布時(shí),斜坡的安全性有一定程度的降低;滑面粘聚力只有達(dá)到與法向應(yīng)力同一量級(jí),對(duì)穩(wěn)定性的影響則變得較為明顯,考慮到Vajont滑坡滑面區(qū)為粘土夾層,粘聚力較小,因此穩(wěn)定性分析時(shí),將粘聚力作用等價(jià)轉(zhuǎn)化為摩擦角作用或不考慮。(3)當(dāng)Vajont滑坡沿著完整滑裂面啟動(dòng)時(shí),滑面及滑體的強(qiáng)度都有相當(dāng)程度的降低,這是造成滑坡加速高速下滑的原因。同樣程度的衰減,滑坡運(yùn)動(dòng)距離對(duì)滑帶強(qiáng)度的降低,表現(xiàn)的更加敏感,而滑體強(qiáng)度的變化是在此基礎(chǔ)上促進(jìn)了滑坡前緣塊體的爬升能力。
[Abstract]:Large landslides, which can slip forward at a very high speed because of their large size, usually bring devastating disasters to settlements along the way. The Vajont landslide occurred in Italy. Vajont landslide is typical of large high speed landslide, which caused the research upsurge of large high speed landslide .Vajont landslide from the beginning to complete collapse to stop production, which lasted less than 1 minute. The maximum slip rate reached an astonishing 20 m / s / s, and the rock slide that rushed towards the reservoir caused a surge of about 100 m high, flooding five villages and towns downstream. More than 2 000 people lost their lives as a result of the disaster. In the current numerical study of Vajont landslide, there is a problem that the parameters of rock mass are not uniform. The reduction of sliding zone friction is considered to be the cause of landslide high speed movement. At this stage, most of the research is to discuss the influence of slip zone strength attenuation on landslide movement ability. However, the study of landslide movement ability caused by strength attenuation of sliding body is relatively scarce. This paper takes Vajont landslide as an example, aiming at the above problems. The characteristics of Vajont landslide in the stable stage and the movement stage are analyzed by using DDA method, and the influence of intensity attenuation on the landslide movement ability is discussed according to the inversion of landslide characteristics. The conclusion is as follows: 1) based on the displacement catastrophe criterion, a method for calculating the critical strength of slope is established, which is verified by the traditional strength reduction method. In the program, the initial strength of sliding surface is automatically reduced once every fixed number of steps. When the displacement of slope characteristic point changes, the corresponding strength is critical strength. 2) the friction angle of jointed rock mass. The cohesive force of sliding surface and the height of static water level have great influence on the stable state of slope. The friction angle of jointed rock mass increases by 5 擄, and the friction angle of sliding face to boundary decreases by 0.5 擄for maintaining slope stability. When the water level of the reservoir rises to the planned maximum water storage height, the slope safety factor decreases by 11.9. due to rainfall and other factors, the water level of the slope is not horizontal distribution. The slope safety is reduced to a certain extent; The cohesive force of sliding surface is only the same as normal stress, and the influence on stability becomes more obvious. Considering that the slip surface area of Vajont landslide is clay intercalation, the cohesion force is small, so the stability analysis. When the Vajont landslide starts along the whole slip surface, the strength of the sliding surface and the sliding body will be reduced to a certain extent. This is the cause of the landslide to accelerate the high-speed slide. The same degree of attenuation, landslide distance to reduce the strength of the slide zone, performance is more sensitive. On the basis of the change of slide strength, the climbing ability of landslide front block is promoted.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P642.22

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