【摘要】：云南作為紅土高原,區(qū)域性紅土廣泛分布,作為一種資源優(yōu)勢(shì),已經(jīng)廣泛運(yùn)用在各種基礎(chǔ)工程設(shè)施中。但是由于自然和人為因素的影響,再加上水位升降及水庫(kù)蓄水引起的干濕循環(huán)過(guò)程和浸泡,常常導(dǎo)致庫(kù)岸失穩(wěn),嚴(yán)重影響了工程安全運(yùn)行和持續(xù)運(yùn)行,且縮短了工程壽命。針對(duì)這一客觀實(shí)際,本文以云南紅土型水庫(kù)庫(kù)岸為研究對(duì)象,采用理論研究與試驗(yàn)研究相結(jié)合的方法,對(duì)云南紅土型庫(kù)岸進(jìn)行穩(wěn)定性研究。通過(guò)開(kāi)展土工試驗(yàn)、干濕循環(huán)試驗(yàn)、微結(jié)構(gòu)試驗(yàn),設(shè)置不同初始干密度、不同初始含水率、不同加砂比例等條件,研究庫(kù)水位升降及浸泡作用下庫(kù)岸紅土宏微觀特性。通過(guò)開(kāi)展室內(nèi)模型庫(kù)岸試驗(yàn),研究庫(kù)岸紅土遷移特性以及典型特征點(diǎn)的孔隙水壓力、土壓力的變化規(guī)律。采用有限元法、極限平衡方法,結(jié)合概率論、土力學(xué)等學(xué)科研究紅土型庫(kù)岸失穩(wěn)的臨界條件,在綜合試驗(yàn)研究和理論研究的基礎(chǔ)上,揭示了庫(kù)水位升降及浸泡作用下紅土型庫(kù)岸失穩(wěn)機(jī)理,這對(duì)有效預(yù)測(cè)和防治紅土型庫(kù)岸失穩(wěn)具有實(shí)際意義。庫(kù)岸紅土宏微觀特性對(duì)庫(kù)岸穩(wěn)定性的影響在于:在整個(gè)干濕循環(huán)過(guò)程中,不同初始干密度、不同初始含水率、不同加砂比例紅土的內(nèi)摩擦角、粘聚力及抗剪強(qiáng)度均隨著循環(huán)次數(shù)的增加而呈下降趨勢(shì),并在循環(huán)10次左右趨于穩(wěn)定。針對(duì)不同初始干密度紅土,在整個(gè)干濕循環(huán)過(guò)程中,內(nèi)摩擦角降幅與初始干密度大小成正相關(guān)關(guān)系,粘聚力、抗剪強(qiáng)度降幅均與初始干密度大小成反相關(guān)關(guān)系;針對(duì)不同初始含水率紅土,在整個(gè)干濕循環(huán)過(guò)程中,內(nèi)摩擦角、粘聚力及抗剪強(qiáng)度降幅最小的是初始含水率為26.5%的紅土,降幅最大的是初始含水率為30.5%的紅土;針對(duì)不同加砂比例紅土,在整個(gè)干濕循環(huán)過(guò)程中,內(nèi)摩擦角、粘聚力及抗剪強(qiáng)度降幅最小的是加砂10%的紅土,降幅最大的是加砂15%的紅土。庫(kù)岸地形地貌對(duì)庫(kù)岸穩(wěn)定性的影響在于:隨著庫(kù)岸坡角的增加,庫(kù)岸安全系數(shù)越來(lái)越小,其中在坡角為45°～50°區(qū)間時(shí),安全系數(shù)降幅最大,在實(shí)際工程中應(yīng)盡量避免處于此危險(xiǎn)區(qū)間的坡角。庫(kù)水升降幅度及速率對(duì)庫(kù)岸穩(wěn)定性的影響在于:庫(kù)水上升階段,坡高的60%為相對(duì)危險(xiǎn)水位,此時(shí)庫(kù)水速率對(duì)庫(kù)岸穩(wěn)定性影響程度相對(duì)較小。庫(kù)水下降階段,坡高的70%為相對(duì)危險(xiǎn)水位,此時(shí)庫(kù)水速率越大,庫(kù)岸安全系數(shù)降幅也就越大,庫(kù)岸越不穩(wěn)定。紅土型庫(kù)岸失穩(wěn)的臨界條件理論研究表明:在水庫(kù)運(yùn)行的第12年,紅土型庫(kù)岸處于失穩(wěn)的臨界狀態(tài),應(yīng)該根據(jù)實(shí)際的工程情況及時(shí)對(duì)水庫(kù)庫(kù)岸進(jìn)行加固處理。庫(kù)水位升降及浸泡作用下紅土型庫(kù)岸失穩(wěn)機(jī)理,實(shí)質(zhì)上是庫(kù)水對(duì)紅土物理、化學(xué)、力學(xué)等多方面共同作用結(jié)果。其中物理作用包括:顆粒的軟化、泥化作用,庫(kù)水對(duì)坡內(nèi)紅土顆粒的遷移作用。化學(xué)作用包括:礦物質(zhì)電離水解、水化作用。力學(xué)作用包括:地下水、孔隙靜水壓力及孔隙動(dòng)水壓力、庫(kù)水浮托力對(duì)庫(kù)岸紅土顆粒作用。
[Abstract]:Yunnan, as a red earth plateau, is widely distributed in the region. As a resource advantage, Yunnan has been widely used in various infrastructure projects. However, due to the influence of natural and human factors, coupled with the rise and fall of water level and the process and immersion of the dry-wet cycle caused by reservoir impoundment, it often leads to the instability of the reservoir bank, which seriously affects the safe operation of the project. In view of this objective reality, this paper takes the Bank of Yunnan laterite reservoir as the research object, and studies the stability of Yunnan laterite reservoir bank by combining theoretical research with experimental research. The macroscopic and microscopic characteristics of laterite in reservoir bank under the action of water level fluctuation and immersion are studied under the conditions of dry density, initial water content and sand ratio. Combining probability theory and soil mechanics, the critical condition of laterite reservoir bank instability is studied. On the basis of comprehensive experimental study and theoretical study, the mechanism of laterite reservoir bank instability under the action of water level fluctuation and immersion is revealed, which is of practical significance for effective prediction and prevention of laterite reservoir bank instability. The influence of stability is that the internal friction angle, cohesion and shear strength of laterites with different initial dry densities, initial water content and sand ratio decrease with the increase of cycling times, and tend to be stable about 10 cycles. During the whole dry-wet cycle, the decrease of internal friction angle is positively related to the initial dry density, and the decrease of cohesion and shear strength is inversely related to the initial dry density. For different proportion of sanded laterite, the lowest reduction of internal friction angle, cohesion and shear strength is 10% sanded laterite, and the greatest reduction is 15% sanded laterite. With the increase of the angle, the safety factor of the reservoir bank becomes smaller and smaller. When the slope angle is between 45 degrees and 50 degrees, the safety factor decreases the most. In practical engineering, the slope angle in this dangerous zone should be avoided as far as possible. The stability of the reservoir bank is less affected by the rate. At the stage of the reservoir downhill, 70% of the slope height is the relative dangerous water level. The larger the rate of the reservoir water, the greater the decrease of the safety factor of the reservoir bank and the more unstable the reservoir bank will be. The failure mechanism of laterite reservoir bank under the action of water level fluctuation and immersion is essentially the result of physical, chemical and mechanical interaction between reservoir water and laterite. Migration of particles. Chemical processes include mineral ionization and hydrolysis, hydration. Mechanics include groundwater, pore hydrostatic pressure and pore hydrodynamic pressure, and reservoir water buoyancy on laterite particles.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TV223

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本文編號(hào)：2238116