【摘要】：黃土是一種典型的非飽和土，我國黃土面積分布廣泛，尤其是在西北部地區(qū)。在黃土地區(qū)地質(zhì)災(zāi)害的發(fā)生多數(shù)情況下都與水的作用有關(guān)。因此非飽和黃土的強(qiáng)度參數(shù)測試與選取對評價黃土邊坡的穩(wěn)定性，防災(zāi)減災(zāi)具有重要的意義。本文以Bishop、Fredlund及Lu Ning的非飽和強(qiáng)度理論為依據(jù)，陜西省延安市延煉滑坡非飽和黃土為研究對象，采用不同含水率的常規(guī)試驗——直剪試驗與三軸試驗，，測定了有效穩(wěn)態(tài)強(qiáng)度參數(shù)，又用張力計測定了同一試樣的水土特征曲線。再根據(jù)延煉滑坡恢復(fù)邊坡，進(jìn)行水分入滲數(shù)值模擬，及應(yīng)力與穩(wěn)定性分析，取得了以下成果： （1）取延煉滑坡Q2與Q1層黃土，配制不同的含水率作為原狀土樣，進(jìn)行了固結(jié)慢剪試驗和三軸CU試驗，得到了不同含水率下黃土的強(qiáng)度參數(shù)粘聚力c和內(nèi)摩擦角φ，分析發(fā)現(xiàn)含水率對黃土的抗剪強(qiáng)度有影響，而且對粘聚力的影響較大，對內(nèi)摩擦角的影響不大。有效穩(wěn)態(tài)粘聚力隨含水率增大而降低，當(dāng)含水率低于塑限時，有效穩(wěn)態(tài)粘聚力隨含水率增加顯著降低。當(dāng)含水率大于塑限時，有效穩(wěn)態(tài)粘聚力趨于一穩(wěn)定值，不再減小。有效穩(wěn)態(tài)摩擦角與含水率沒有明顯的相關(guān)性，基本上是一個穩(wěn)定的值，不隨含水率的變化而變化。 （2）根據(jù)基質(zhì)吸力試驗得到黃土的土—水特征曲線，可以看出含水率與基質(zhì)吸力的關(guān)系。基質(zhì)吸力與含水率呈指數(shù)關(guān)系，隨著含水率的增大，基質(zhì)吸力逐漸降低。 （3）結(jié)合非飽和黃土強(qiáng)度參數(shù)與土水特征曲線，可以計算出非飽和土強(qiáng)度理論中Bishop的單變量理論強(qiáng)度參數(shù)χ和Fredlund的雙變量理論φb。又根據(jù)Lu Ning提出的吸應(yīng)力概念，得出了吸應(yīng)力和體積含水率的關(guān)系曲線，即吸應(yīng)力特征函數(shù)。并對這三種非飽和強(qiáng)度理論進(jìn)行對比分析。Lu Ning的非飽和強(qiáng)度直接用吸應(yīng)力函數(shù)表達(dá)，該強(qiáng)度公式回避了測定基質(zhì)吸力的問題，便于在工程實際中推廣。 （4）針對延煉滑坡滑動前地形，通過Geo-studio軟件建立數(shù)值模型，模擬水分入滲時邊坡土體內(nèi)水位線及孔隙水壓力隨時間的變化。再利用非飽和土抗剪強(qiáng)度公式，并結(jié)合本文試驗得出的非飽和黃土公式強(qiáng)度參數(shù)，計算蒸氣冷凝入滲時邊坡滑面上抗剪強(qiáng)度，以及邊坡的穩(wěn)定性。
[Abstract]:Loess is a typical unsaturated soil. Loess is widely distributed in China, especially in northwest China. The occurrence of geological disasters in loess area is mostly related to the action of water. Therefore, the test and selection of the strength parameters of unsaturated loess is of great significance to evaluate the stability of loess slope and to prevent and reduce the disaster. Based on the unsaturated strength theory of Bishop,Fredlund and Lu Ning, the unsaturated loess of Yanlian landslide in Yanan City, Shaanxi Province is taken as the research object. The conventional tests of different moisture content, direct shear test and triaxial test, are adopted in this paper. The effective steady-state strength parameters were measured, and the soil and water characteristic curves of the same sample were measured by the tensometer. According to the slope restoration of Yanlian landslide, the numerical simulation of water infiltration and the analysis of stress and stability are carried out. The following results are obtained: (1) taking the loess of Q2 and Q1 layers of Yan-Lian landslide, different moisture content is prepared as undisturbed soil sample. The consolidation slow shear test and triaxial CU test were carried out, and the cohesive force c and internal friction angle 蠁 of loess strength parameters under different moisture content were obtained. It was found that moisture content had an effect on the shear strength of loess, and had a great effect on cohesion. It has little effect on the angle of internal friction. The effective steady-state cohesion decreases with the increase of moisture content. When the moisture content is lower than the plastic limit, the effective steady-state cohesion decreases significantly with the increase of moisture content. When the moisture content is larger than the plastic limit, the effective steady-state cohesive force tends to a stable value and no longer decreases. There is no obvious correlation between the effective steady state friction angle and the moisture content, which is basically a stable value and does not change with the change of the moisture content. (2) the soil-water characteristic curve of loess is obtained by the matrix suction test, and the relation between the moisture content and the matrix suction can be seen. The matrix suction was exponentially related to the moisture content, and the matrix suction decreased gradually with the increase of the moisture content. (3) combining the strength parameters of unsaturated loess with soil-water characteristic curves, the univariate theoretical strength parameter 蠂 of Bishop and the bivariate theory of 蠁 b of Fredlund can be calculated in unsaturated soil strength theory. According to the concept of absorptive stress put forward by Lu Ning, the curve of relation between suction stress and volume moisture content is obtained, that is, the characteristic function of absorptive stress. The three theories of unsaturated strength are compared and analyzed. The unsaturated strength of. Lu Ning is expressed directly by the absorptive stress function. The strength formula avoids the problem of measuring the suction of matrix and is easy to be popularized in engineering practice. (4) according to the topography of Yanlian landslide before sliding, a numerical model was established by Geo-studio software to simulate the variation of soil water level and pore water pressure with time during the infiltration of water. Then the shear strength formula of unsaturated soil and the strength parameters of unsaturated loess formula obtained in this paper are used to calculate the shear strength on the slip surface of the slope and the stability of the slope.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU444

【參考文獻(xiàn)】

中國期刊全文數(shù)據(jù)庫 前9條

1 王釗,鄒維列,李俠;非飽和土吸力測量及應(yīng)用[J];四川大學(xué)學(xué)報(工程科學(xué)版);2004年02期

2 王志玲,豐土根;非飽和土的抗剪強(qiáng)度理論研究[J];水利水電科技進(jìn)展;2002年04期

3 李靖,黨進(jìn)謙,劉祖典;非飽和黃土中的吸力與有效應(yīng)力[J];西北農(nóng)業(yè)大學(xué)學(xué)報;1997年04期

4 凌華;殷宗澤;;非飽和土強(qiáng)度隨含水量的變化[J];巖石力學(xué)與工程學(xué)報;2007年07期

5 蔣彭年;非飽和土工程性質(zhì)簡論[J];巖土工程學(xué)報;1989年06期

6 沈珠江;;非飽和土力學(xué)實用化之路探索[J];巖土工程學(xué)報;2006年02期

7 林鴻州;李廣信;于玉貞;呂禾;;基質(zhì)吸力對非飽和土抗剪強(qiáng)度的影響[J];巖土力學(xué);2007年09期

8 張常亮;王阿丹;邢鮮麗;王昌業(yè);李同錄;李萍;;侵蝕作用誘發(fā)黃土滑坡的機(jī)制研究[J];巖土力學(xué);2012年05期

9 趙成剛;李艦;劉艷;蔡國慶;ASREAZAD Saman;;非飽和土力學(xué)中幾個基本問題的探討[J];巖土力學(xué);2013年07期

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