發(fā)布時(shí)間：2018-05-17 06:21

  本文選題：降雨 + 邊坡穩(wěn)定性　； 參考：《上海交通大學(xué)》2015年碩士論文

【摘要】：滑坡是一種具有突發(fā)性和災(zāi)難性的地質(zhì)災(zāi)害,降雨是誘發(fā)滑坡災(zāi)害的主要原因。天然斜坡在沉積、風(fēng)化等作用下呈現(xiàn)粗細(xì)夾雜的地層條件,具有顯著的空間變異特性。在降雨入滲作用下土坡內(nèi)細(xì)顆粒會(huì)隨滲流發(fā)生運(yùn)移產(chǎn)生潛蝕作用。因此,揭示降雨作用下土體潛蝕機(jī)制,研究滲流潛蝕對(duì)土坡穩(wěn)定性的影響規(guī)律,具有重要的理論意義和工程實(shí)踐價(jià)值。本文以無(wú)限邊坡為研究對(duì)象,基于多孔介質(zhì)動(dòng)力學(xué)和非飽和土力學(xué)理論,采用數(shù)值分析的方法,進(jìn)行了有限元模擬分析,探討了潛蝕作用對(duì)雨水入滲和邊坡穩(wěn)定性的影響規(guī)律。主要研究?jī)?nèi)容和成果如下:1.通過(guò)聯(lián)立顆粒運(yùn)移方程與非飽和土滲流方程,結(jié)合非飽和土水力特性方程、土體潛蝕本構(gòu)關(guān)系以及土壤轉(zhuǎn)換函數(shù),建立了滲流潛蝕耦合的邊坡穩(wěn)定性分析模型。2.利用COMSOL軟件建立均質(zhì)無(wú)限邊坡有限元模型,對(duì)強(qiáng)降雨條件下邊坡土體內(nèi)細(xì)顆粒運(yùn)移和潛蝕進(jìn)行了模擬,研究了滲流潛蝕對(duì)孔壓分布和邊坡穩(wěn)定性的影響,探討了飽和滲透系數(shù)、進(jìn)氣值和潛蝕本構(gòu)模型參數(shù)對(duì)滲流潛蝕的影響。結(jié)果表明:潛蝕主要發(fā)生在濕潤(rùn)鋒范圍內(nèi)淺層土體,潛蝕加速了濕潤(rùn)鋒下行速度,進(jìn)一步降低邊坡穩(wěn)定性;飽和滲透系數(shù)、進(jìn)氣值是影響滲流潛蝕作用的主要因素;當(dāng)降雨入滲強(qiáng)度大于飽和滲透系數(shù)時(shí),飽和滲透系數(shù)越大,潛蝕對(duì)入滲和邊坡穩(wěn)定性的影響越顯著;進(jìn)氣值越小,潛蝕作用對(duì)入滲和邊坡穩(wěn)定性的影響越顯著。3.對(duì)四種不同顆粒成分土坡算例進(jìn)行了滲流潛蝕模擬,引入基于非飽和土特性參數(shù)的土壤轉(zhuǎn)換函數(shù),考慮滲流潛蝕過(guò)程中顆粒成分動(dòng)態(tài)變化的影響,分析了不同顆粒成分情況下,潛蝕作用對(duì)降雨入滲和邊坡穩(wěn)定性的影響規(guī)律。結(jié)果表明,當(dāng)細(xì)顆粒含量大于30%的情況下,潛蝕作用對(duì)滲流和邊坡穩(wěn)定影響不明顯;細(xì)顆粒含量小于30%的情況下,滲流潛蝕對(duì)邊坡的穩(wěn)定性有顯著的影響。4.采用隨機(jī)場(chǎng)模擬土的空間變異性,對(duì)土性參數(shù)進(jìn)行離散化,生成空間各點(diǎn)土性參數(shù)樣本。對(duì)不同類型非均質(zhì)性土坡的滲流潛蝕進(jìn)行了有限元分析模擬,揭示了非均勻性對(duì)潛蝕發(fā)展過(guò)程及局部和整體穩(wěn)定性的影響規(guī)律。5.對(duì)試驗(yàn)配備的土樣進(jìn)行了土柱滲流潛蝕試驗(yàn)研究,觀察潛蝕現(xiàn)象的發(fā)生,分析了土體滲流潛蝕的發(fā)展規(guī)律。觀測(cè)結(jié)果表明:滲流速度與細(xì)顆粒流失累計(jì)量成非線性關(guān)系,隨著滲流速度的增大,細(xì)顆粒會(huì)持續(xù)流出,但是流出量逐漸減小;累計(jì)流失質(zhì)量是增加的,但其增加速率逐漸減小。
[Abstract]:Landslide is a sudden and catastrophic geological disaster, and rainfall is the main cause of landslide disaster. The natural slopes show thick and fine stratigraphic conditions under the action of sedimentation and weathering, and have remarkable spatial variation characteristics. Under the effect of rainfall infiltration, the fine particles in the soil slope will move with the seepage to produce the latent erosion. Therefore, it is of great theoretical significance and practical value to reveal the underlying erosion mechanism of soil under rainfall and to study the influence of seepage erosion on the stability of soil slope. Based on the dynamics of porous media and the theory of unsaturated soil mechanics, finite element simulation analysis of infinite slope is carried out by means of numerical analysis, and the influence of latent erosion on Rain Water infiltration and slope stability is discussed in this paper. The main research contents and results are as follows: 1. Through simultaneous particle transport equation and unsaturated soil seepage equation, combined with unsaturated soil hydraulic characteristic equation, soil latent erosion constitutive relation and soil transformation function, the slope stability analysis model of seepage and erosion coupling is established. The finite element model of homogeneous infinite slope is established by using COMSOL software. The fine particle migration and subsurface erosion in slope soil under heavy rainfall are simulated. The influence of seepage erosion on pore pressure distribution and slope stability is studied, and the saturated permeability coefficient is discussed. The influence of intake value and constitutive model parameters of latent erosion on seepage erosion. The results show that the subsurface erosion mainly occurs in shallow soil within the range of the wetting front, which accelerates the downward velocity of the wetting front and further reduces the slope stability, the saturation permeability coefficient and the intake value are the main factors affecting the seepage potential erosion. When the rainfall infiltration intensity is greater than the saturation permeability coefficient, the larger the saturation permeability coefficient, the more significant the influence of the latent erosion on the infiltration and slope stability, and the smaller the intake value, the more significant the influence of the latent erosion on the infiltration and slope stability. In this paper, four examples of soil slope with different particle composition are simulated. The soil transformation function based on the characteristic parameters of unsaturated soil is introduced, and the influence of the dynamic change of particle composition in the process of seepage erosion is considered, and the different particle composition is analyzed. The influence of latent erosion on rainfall infiltration and slope stability. The results show that when the content of fine particles is more than 30%, the effect of subsurface erosion on the seepage flow and slope stability is not obvious, and when the content of fine particles is less than 30%, the seepage erosion has a significant effect on the slope stability. The random field simulation of soil spatial variability is used to discretize soil parameters and to generate samples of soil parameters at various points in space. The seepage potential erosion of different types of heterogeneous soil slopes was simulated by finite element analysis, and the influence of heterogeneity on the development process and local and global stability of subsurface erosion was revealed. The experimental study of soil column seepage latent erosion was carried out on the soil samples, the occurrence of latent erosion phenomenon was observed, and the development law of soil seepage latent erosion was analyzed. The results show that the seepage velocity has a nonlinear relationship with the cumulative loss of fine particles. With the increase of the seepage velocity, the fine particles will continue to flow out, but the outflow volume will gradually decrease, and the cumulative loss mass will increase. But its increasing rate gradually decreased.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P642.22

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