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  本文關(guān)鍵詞： 非飽和黃土 降雨入滲 蒸發(fā) 邊坡 穩(wěn)定性　出處：《蘭州交通大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：黃土大多數(shù)是含水量低的非飽和土,氣候變化對地表附近黃土的含水量影響很大。黃土在受水浸濕作用前處于非飽和狀態(tài),非飽和黃土在降雨作用下極易達(dá)到局部飽和狀態(tài),由此引起抗剪強度快速減小,孔隙水壓力為負(fù)值(由于大部分情況下孔隙氣壓力為零,所以其值等于基質(zhì)吸力),進(jìn)而引起邊坡的安全系數(shù)減小,甚至導(dǎo)致黃土邊坡產(chǎn)生滑坡。通過研究發(fā)現(xiàn),水分滲入是引起滑坡的主要原因,但是人們對于這種關(guān)系的認(rèn)識和理解還不夠充分。在滑坡整治過程中,如果能科學(xué)合理地確定滑坡體所在邊坡的水分場和溫度變化趨勢,這將極大節(jié)省工程投資。本文在學(xué)習(xí)、歸納非飽和黃土邊坡理論研究的基礎(chǔ)上,以蘭州馬蘭黃土為研究對象,結(jié)合室內(nèi)物性試驗和模型試驗,定性與定量分析相結(jié)合,對水氣交換作用下的非飽和黃土邊坡穩(wěn)定性進(jìn)行了系統(tǒng)研究,取得了一些有價值的研究成果。首先,對所選用的非飽和黃土的填土土樣進(jìn)行了室內(nèi)物理特性的測試,測定了其級配曲線、最優(yōu)含水率、最大干密度、液塑限指數(shù)、滲透系數(shù)等,為下一步試驗做好準(zhǔn)備工作。其次,設(shè)計了非飽和黃土邊坡的室內(nèi)模型,通過利用手動噴霧器對坡體進(jìn)行水分入滲和保暖燈模擬日照,進(jìn)行邊坡土體內(nèi)水氣變化及邊坡穩(wěn)定性的試驗研究。模型試驗采用水分測試裝置、溫度測試裝置、位移測試裝置對模型內(nèi)土體進(jìn)行聯(lián)合監(jiān)測,記錄了水分入滲及模擬日照的情況下模型內(nèi)土體的水分、溫度、位移變化過程。對其進(jìn)行了系統(tǒng)詳實研究,旨在研究非飽和黃土邊坡在水分入滲和日照條件下的水分場及溫度場的規(guī)律,對非飽和黃土邊坡地質(zhì)災(zāi)害的形成機制進(jìn)行分析,為邊坡破壞機理提供理論支持,并為在建工程提供設(shè)計依據(jù)。再次,在前述非飽和黃土水氣交換模型試驗的基礎(chǔ)上,通過非飽和滲流軟件SEEP/W模擬了蘭州九州石峽口南部的黃土高邊坡在不同降雨強度和降雨持時條件下的降雨入滲,得出了計算模型不同層位的的孔隙水壓力和體積含水量。最后利用之前的非飽和滲流分析結(jié)果,耦合到SLOPE/W中進(jìn)行邊坡穩(wěn)定性分析,通過對不同降雨強度變化研究,來探討抗剪強度和孔隙水壓力隨深度的變化。
[Abstract]:Loess is mostly unsaturated soil with low water content, and climate change has a great influence on the water content of loess near the surface. The loess is in unsaturated state before being soaked by water, and unsaturated loess is easy to reach local saturation state under the action of rainfall. As a result, the shear strength decreases rapidly, and the pore water pressure is negative (because in most cases the pore gas pressure is zero, so its value is equal to the matrix suction, thus causing the slope safety factor to decrease. Through the research, it is found that water infiltration is the main cause of the landslide, but the understanding of this relationship is not enough. If the water field and temperature change trend of the slope where the landslide body is located can be determined scientifically and reasonably, the project investment will be greatly saved. In this paper, on the basis of studying and summarizing the theoretical research of unsaturated loess slope, taking Ma Lan loess in Lanzhou as the research object, Combined with indoor physical property test and model test, combined with qualitative and quantitative analysis, the stability of unsaturated loess slope under the action of water and air exchange is studied systematically, and some valuable research results are obtained. The indoor physical properties of the unsaturated loess filled soil samples were tested, and the gradation curve, optimal moisture content, maximum dry density, liquid-plastic limit index, permeability coefficient and so on were determined. The indoor model of unsaturated loess slope was designed, and the water infiltration and heat preservation lamp were simulated by manual sprayer. In the model test, the moisture test device, the temperature test device and the displacement test device are used to monitor the soil mass in the model. The changes of soil moisture, temperature and displacement in the model were recorded under the condition of water infiltration and simulated sunshine. The purpose of this paper is to study the regularity of water field and temperature field of unsaturated loess slope under the condition of water infiltration and sunshine, to analyze the formation mechanism of geological hazard of unsaturated loess slope, and to provide theoretical support for the failure mechanism of unsaturated loess slope. And provide the design basis for the project under construction. Thirdly, on the basis of the above unsaturated loess water and gas exchange model test, The infiltration of loess high slope in the south of Shixiakou, Jiuzhou, Lanzhou was simulated by unsaturated seepage software SEEP/W under different rainfall intensity and duration. The pore water pressure and volume water content of different layers of the model are obtained. Finally, using the results of unsaturated seepage analysis before, the slope stability is analyzed by coupling to SLOPE/W, and the variation of different rainfall intensity is studied. To study the variation of shear strength and pore water pressure with depth.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU411;TU444

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本文編號：1524327