本文關(guān)鍵詞： 重塑黃土 含水量 三軸試驗(yàn) 強(qiáng)度特性 應(yīng)力-應(yīng)變 體應(yīng)變　出處：《長(zhǎng)安大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：黃土是一種特殊性土，屬于我國(guó)西北地區(qū)一種最常見的土工材料，既可以作為建筑材料使用，又是多種建筑依存的工程環(huán)境。諸多學(xué)者對(duì)黃土的分布、成因、行為特性和變形強(qiáng)度特性等方面的研究和實(shí)踐均取得了顯著成果，但是對(duì)于以初始含水量作為狀態(tài)變量的飽和-非飽和黃土的應(yīng)力-應(yīng)變、體應(yīng)變和強(qiáng)度特性的研究較少。本文在借鑒已有研究成果的基礎(chǔ)上，以陜西省延安市Q2黃土為研究對(duì)象，應(yīng)用改進(jìn)后的非飽和土三軸試驗(yàn)儀，進(jìn)行了控制含水量的飽和-非飽和重塑黃土（ρd=1.6g/cm3）常規(guī)三軸壓縮應(yīng)力路徑（CTC）下的固結(jié)排水剪切試驗(yàn)。分別就不同初始含水量和圍壓狀態(tài)下的應(yīng)變結(jié)果定性進(jìn)行了應(yīng)力-應(yīng)變特性和變形特性分析，就不同初始含水量條件下應(yīng)力結(jié)果定量進(jìn)行了強(qiáng)度特性分析。得出的結(jié)論如下： （1）重塑黃土的應(yīng)力-應(yīng)變曲線隨初始含水量的增大逐漸由應(yīng)變軟化型向穩(wěn)定型和應(yīng)變硬化型轉(zhuǎn)變，相應(yīng)的直線、雙曲函數(shù)和冪函數(shù)對(duì)其分別具有較好的擬合效果；圍壓對(duì)于重塑黃土的應(yīng)力-應(yīng)變形式不產(chǎn)生顯著影響。 （2）重塑黃土在受力時(shí)抵抗變形的能力隨著含水量的增加而降低，產(chǎn)生的體積變化量也與含水量密切相關(guān)，低含水量的土體在剪切過程中發(fā)生“剪脹”現(xiàn)象，高含水量土體在剪切過程中產(chǎn)生“剪縮”現(xiàn)象；土體由膨脹到收縮的體積變化趨勢(shì)還可以通過增加圍壓來實(shí)現(xiàn)。 （3）重塑黃土粘聚力和內(nèi)摩擦因數(shù)均隨含水量的增加非線性降低，存在含水量特殊狀態(tài)點(diǎn)控制著粘聚力與內(nèi)摩擦角的轉(zhuǎn)折和發(fā)展趨勢(shì)，可利用特殊狀態(tài)點(diǎn)將非線性關(guān)系表達(dá)為冪函數(shù)。 本文采用含水量作為狀態(tài)變量，對(duì)非飽和重塑黃土抗剪強(qiáng)度和極限荷載進(jìn)行擬合，該擬合公式形式簡(jiǎn)單，參數(shù)少，，物理意義明確，擬合結(jié)果偏安全，因此，在工程實(shí)用中是一條計(jì)算任意含水量條件下土體強(qiáng)度的簡(jiǎn)便途徑。
[Abstract]:Loess is a kind of special soil, which belongs to the most common geotechnical material in Northwest China. It can be used as building materials, and it is also a kind of engineering environment dependent on many kinds of buildings. Many scholars have studied the distribution and origin of loess. Remarkable achievements have been made in the research and practice of behavior characteristics and deformation strength characteristics, but the stress-strain of saturated-unsaturated loess with initial water content as the state variable has been obtained. There are few studies on bulk strain and strength characteristics. Based on the existing research results, this paper takes Q2 loess in Yanan City, Shaanxi Province as the research object, and applies the improved unsaturated soil triaxial test instrument. Saturated unsaturated remolded loess (蟻 _ d _ (1.6 g / cm ~ (3)) under normal triaxial compression stress path (CTC) was carried out to control water content. The stress-strain characteristics and deformation characteristics of strain results under different initial water content and confining pressure were qualitatively analyzed. The strength characteristics of the stress results under different initial water contents are analyzed quantitatively. The conclusions are as follows: 1) the stress-strain curve of remolded loess changes gradually from strain softening type to stable type and strain hardening type with the increase of initial water content. Hyperbolic function and power function have better fitting effect respectively. Confining pressure has no significant effect on the stress-strain form of remolded loess. (2) the ability to resist deformation of remolded loess decreases with the increase of water content, and the volume change is closely related to water content. The phenomenon of "shear expansion" occurs in the shear process of the soil with low water content, and the phenomenon of "shearing shrinkage" occurs in the shear process of the soil with high water content. The change of soil volume from expansion to contraction can also be achieved by increasing confining pressure. 3) the cohesive force and internal friction coefficient of remolded loess decrease nonlinear with the increase of water content, and there is a special point of water content controlling the turning point and developing trend of cohesion and internal friction angle. The nonlinear relation can be expressed as a power function by using special state points. In this paper, the water content is used as the state variable to fit the shear strength and ultimate load of unsaturated remolded loess. The fitting formula is simple in form, few in parameters, clear in physical meaning and safe in fitting results. It is a simple and convenient way to calculate the strength of soil under the condition of arbitrary water content in engineering practice.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU444;TU411

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