本文關(guān)鍵詞： 纖維改良土 凍融循環(huán)試驗 動三軸試驗 靜三軸試驗 導(dǎo)熱系數(shù)試驗 動/靜本構(gòu)模型 熱物理統(tǒng)計模型　出處：《北京交通大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：了解纖維改良土的凍結(jié)行為對寒區(qū)的地基技術(shù)、道路與土方工程至關(guān)重要。本文的主要目的是:研究纖維改良土在數(shù)次凍融循環(huán)下的物理、力學(xué)、熱力學(xué)的性質(zhì),并利用Stefan方程與改進Berggren方程預(yù)測土耳其東部地區(qū)的最大凍深。為了完成這個目標(biāo),對經(jīng)歷凍融循環(huán)后的纖維改良土(隨機摻加玻璃纖維、玄武巖纖維、鋼纖維、粉煤灰、木質(zhì)素)的物理性質(zhì),如:質(zhì)量損失、含水量變化與試樣高度等指標(biāo)進行測量。進一步地,纖維改良土的熱力學(xué)性質(zhì)總結(jié)為與凍融循環(huán)次數(shù)、纖維含量、溫度有關(guān)的函數(shù)。為了驗證試驗結(jié)果,建立一種熱物理統(tǒng)計模型來模擬不同凍融循環(huán)、溫度條件下的纖維改良土。此外,進行了兩大組UU三軸試驗來驗證纖維改良土的力學(xué)性質(zhì),試驗變量包括:①纖維(玻璃、玄武巖)、纖維含量(0,0.5和1%),凍融循環(huán)次數(shù)(0,2,5,10,和15),圍壓(100,200,和300kPa);②纖維與含量(粉煤灰,4和8%;木質(zhì)素,0,0.25,0.5,0.75和1%),凍融循環(huán)次數(shù)(0和15),圍壓(100,200,和300kPa)。使用兩種Duncan-Chang雙曲線模型預(yù)測凍融條件下纖維改良土的靜應(yīng)力-應(yīng)變關(guān)系。此外,進行了動三軸試驗,變量為:纖維(玻璃,玄武巖),纖維含量(0,0.5和 1%),圍壓(300,400 和 500kPa),凍融循環(huán)次數(shù)(0,2,5,10,和 15)。為了驗證凍融條件下纖維改良土的動剪應(yīng)力、動剪切模量,選用Hardin-Drnevich模型和Kondner-Zelasko模型,建立了剪切模量與凍融次數(shù)、纖維含量、圍壓、初始含水量之間非線性關(guān)系。試驗結(jié)果表明,摻加不同含量的纖維有助于提高地基土的工程性質(zhì)(凍融條件下的熱、力參數(shù)),并且不同纖維含量、凍融循環(huán)下的纖維改良土的試驗結(jié)果與數(shù)學(xué)模型擬合效果優(yōu)。
[Abstract]:It is very important to understand the freezing behavior of fiber modified soil for foundation technology, road and earthwork in cold region. The main purpose of this paper is to study the physics and mechanics of fiber modified soil under several freeze-thaw cycles. Thermodynamic properties, and the use of Stefan equation and improved Berggren equation to predict the maximum freezing depth in eastern Turkey. Physical properties, such as mass loss, of fiber modified soils (randomly mixed with glass fiber, basalt fiber, steel fiber, fly ash, lignin) after freeze-thaw cycle were studied. Further, the thermodynamic properties of fiber modified soil were summarized as functions related to the number of freeze-thaw cycles, fiber content and temperature. A thermophysical statistical model was established to simulate the fiber modified soil under different freezing and thawing cycles. In addition, two groups of UU triaxial tests were carried out to verify the mechanical properties of the fiber modified soil. The experimental variables include: 1 fiber (glass, basalt, fiber content: 0. 5 and 1), freezing and thawing cycles: 0, 2, 5, 10, and 15, 2, 100, 200, respectively. And 300 KPA; (2) fibre and content (4 and 8% fly ash); The number of cycles of freezing and thawing is 0 and 15, and the confining pressure is 100 ~ 200. Two Duncan-Chang hyperbolic models were used to predict the static stress-strain relationship of fiber-modified soils under freeze-thaw conditions. In addition, dynamic triaxial tests were carried out. The variables are as follows: fiber (glass, basalt), fiber content (0, 0, 0. 5 and 1), confining pressure, 300, 400 and 500 KPA, freezing and thawing cycles. In order to verify the dynamic shear stress and dynamic shear modulus of fiber-modified soil under freeze-thaw condition, Hardin-Drnevich model and Kondner-Zelasko model are selected. The nonlinear relationship between shear modulus and freeze-thaw times, fiber content, confining pressure and initial water content is established. Adding different content of fiber can improve the engineering properties of foundation soil (thermal and mechanical parameters under freeze-thaw condition, and different fiber content). The experimental results of fiber-modified soil under freeze-thaw cycle fit well with the mathematical model.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TU43

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本文編號：1444214