本文選題：非飽和土 + 持水曲線��； 參考：《西安理工大學(xué)》2017年碩士論文

【摘要】：持水和滲透特性是非飽和土領(lǐng)域的核心問(wèn)題。文本在回顧前人的基礎(chǔ)上,利用已有文獻(xiàn)中試驗(yàn)實(shí)測(cè)值及數(shù)值計(jì)算,分別對(duì)壓實(shí)黏土的孔徑分布演化持水曲線模型、斑脫土滯回持水曲線模型、土的非飽和滲透各向異性、以及黏土顆粒液橋演化規(guī)律進(jìn)行了研究,并得到如下認(rèn)識(shí):(1)基于典型持水曲線模型對(duì)壓實(shí)黏土提出一種考慮團(tuán)粒內(nèi)孔隙和團(tuán)粒間孔隙的持水曲線模型,從而對(duì)壓實(shí)黏土建立表征團(tuán)粒結(jié)構(gòu)沿不同水力—力學(xué)路徑演化的持水曲線模型。利用已有文獻(xiàn)中兩種壓實(shí)黏土在不同增、減濕和加載路徑下的孔徑分布實(shí)測(cè)數(shù)據(jù),標(biāo)定持水曲線模型中的參數(shù),基于這些實(shí)測(cè)數(shù)據(jù)可討論不同水力—力學(xué)路徑下與進(jìn)氣值有關(guān)參數(shù)的演化規(guī)律。最后,利用已有文獻(xiàn)中這兩種黏土壓實(shí)至不同干密度土樣的持水實(shí)測(cè)數(shù)據(jù)驗(yàn)證了持水曲線模型在表征壓實(shí)黏土沿不同水力—力學(xué)路徑的水力特性以及模擬團(tuán)粒結(jié)構(gòu)演化過(guò)程的有效性。(2)在分析了已有文獻(xiàn)中高膨脹性土(MX-80斑脫土)的持水試驗(yàn)結(jié)果后,以彈塑性理論和線性各向異性硬化規(guī)律為基礎(chǔ),推導(dǎo)出了考慮孔隙比和團(tuán)粒內(nèi)孔隙結(jié)構(gòu)變化的滯回持水曲線模型,土樣給定壓實(shí)狀態(tài)的掃描持水特性可通過(guò)考慮不同飽和度階段的團(tuán)粒內(nèi)孔隙比變化規(guī)律來(lái)表征。最后,利用已有文獻(xiàn)中斑脫土試樣的滯回持水曲線實(shí)測(cè)值對(duì)受孔隙比和團(tuán)粒內(nèi)孔隙結(jié)構(gòu)演化影響的滯回持水曲線以及掃描持水曲線的有效性進(jìn)行驗(yàn)證。結(jié)果表明:所提模型均能夠較好的預(yù)測(cè)斑脫土滯回持水曲線實(shí)測(cè)值。(3)在Mualem提出的非飽和滲透系數(shù)函數(shù)的基礎(chǔ)上,通過(guò)引入孔隙—連通彎曲參數(shù)推導(dǎo)出了關(guān)于有效飽和度的各向異性系數(shù)表達(dá)式,同時(shí)又根據(jù)該表達(dá)式將非飽和滲透各向異性劃分了9種不同類(lèi)型,研究其在不同條件下的適用性。利用已有文獻(xiàn)中非飽和滲透系數(shù)數(shù)值試驗(yàn)結(jié)果驗(yàn)證了該表達(dá)式的有效性。最后,結(jié)合Van Genuchten-Mualem函數(shù),利用該表達(dá)式定量描述基質(zhì)吸力對(duì)已有文獻(xiàn)中5種土的非飽和滲透各向異性的影響。結(jié)果表明:該表達(dá)式能夠描述各向異性系數(shù)隨基質(zhì)吸力的變化規(guī)律。(4)參考已有文獻(xiàn)中粗顆粒模型的簡(jiǎn)化方法,將黏土顆粒簡(jiǎn)化為一對(duì)相互平行的片狀顆粒,且不考慮其表面粗糙度的影響并將其間水分視為液橋。然后,以Yang-Laplace方程為基礎(chǔ),結(jié)合黏土顆粒間液橋的幾何參數(shù)推導(dǎo)出關(guān)于無(wú)量綱液橋體積與固—液接觸角的無(wú)量綱液橋毛細(xì)力的表達(dá)式。令該表達(dá)式為零,繪制無(wú)量綱液橋體積與固—液接觸角的關(guān)系曲線,并根據(jù)液橋從形成至斷裂整個(gè)過(guò)程將該關(guān)系曲線劃分為三個(gè)區(qū)域。最后,整理已有文獻(xiàn)中的實(shí)測(cè)數(shù)據(jù),并通過(guò)該表達(dá)式分析了液橋形成時(shí)毛細(xì)力與液橋體積和固—液接觸角間的關(guān)系。
[Abstract]:Water retention and permeability are the core problems in unsaturated soils. On the basis of reviewing the previous studies, using the experimental data and numerical calculation in previous literatures, the evolution of pore size distribution of compacted clay, the model of hysteretic retention curve, and the unsaturated permeability anisotropy of the soil are studied, respectively. And the evolution law of clay particle liquid bridge is studied, and the following understanding is obtained: 1) based on the typical water retention curve model, a water retention curve model is proposed for compacted clay, which takes into account the inner and intergranular pores of the compacted clay. Thus, the water retention curve model of compacted clay is established to characterize the evolution of aggregate structure along different hydraulic and mechanical paths. The parameters of the water-holding curve model are calibrated by using the measured data of pore size distribution of two compacted clay soils under different increasing, dehumidifying and loading paths in previous literatures. Based on these measured data, the evolution law of parameters related to inlet air value under different hydraulic and mechanical paths can be discussed. Finally, Using the measured water retention data of the two clay compacted to different dry density soil samples in the literature, the hydraulic characteristics of the compacted clay along different hydraulic-mechanical paths and the evolution of aggregate structure are verified by the water-holding curve model. The effectiveness of the process. (2) after analyzing the water holding test results of the highly expansive soil MX-80), Based on the elastic-plastic theory and the linear anisotropic hardening law, a hysteretic water retention curve model considering the change of void ratio and pore structure in pellets is derived. The scanning water holdup characteristics of soil samples in given compaction state can be characterized by considering the variation of void ratio in aggregates at different saturation stages. Finally, the effectiveness of the hysteresis water retention curve and the scanning water retention curve affected by the porosity ratio and the evolution of the pore structure in the aggregates are verified by the measured values of the hysteresis water retention curve of the spot soil samples in the previous literature. The results show that the proposed models can be used to predict the measured values of hysteresis water retention curve of spot desoiling soil. The proposed model is based on the unsaturated permeability coefficient function proposed by Mualem. The expression of effective saturation anisotropy coefficient is derived by introducing porosity and connected bending parameters. According to the expression, the unsaturated permeability anisotropy is divided into nine different types. Its applicability under different conditions is studied. The validity of the expression is verified by the numerical results of unsaturated permeability coefficient in the literature. Finally, combined with the Van Genuchten-Mualem function, the effect of matrix suction on unsaturated permeability anisotropy of five soils is quantitatively described. The results show that the expression can describe the variation of anisotropic coefficient with the matrix suction. (4) referring to the simplified method of coarse particle model, the clay particle can be simplified into a pair of parallel flake particles. The effect of surface roughness is not considered and the moisture content is regarded as a liquid bridge. Then, based on the Yang-Laplace equation and the geometric parameters of the liquid bridge between clay particles, an expression for the dimensionless capillary force of the dimensionless liquid bridge with the contact angle between solid and liquid is derived. When the expression is zero, the relation curve between the volume of dimensionless liquid bridge and the solid-liquid contact angle is drawn, and the relationship curve is divided into three regions according to the whole process from the formation of the liquid bridge to the fracture. Finally, the measured data in the previous literatures are collected and the relationship between capillary force and the volume of liquid bridge and the solid-liquid contact angle is analyzed by the expression.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TU43

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本文編號(hào)：1933207