本文關(guān)鍵詞：流變相物質(zhì)對軟土流變特性影響試驗(yàn)與分析　出處：《華南理工大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 流變相物質(zhì) 軟土 流變特性 強(qiáng)度特性 機(jī)理分析 直剪蠕變試驗(yàn) 壓縮蠕變試驗(yàn) 數(shù)值模擬計算

【摘要】：軟土是一種廣泛分布于沿海、江河、湖泊和濕地等地區(qū)的復(fù)雜天然多孔介質(zhì)，近年來隨著經(jīng)濟(jì)的發(fā)展和城鎮(zhèn)化水平的不斷提高，軟土工程的開發(fā)和利用不斷發(fā)展。大量工程經(jīng)驗(yàn)和研究表明，軟土的變形需要較長時間才可達(dá)到穩(wěn)定。軟土的這種應(yīng)力應(yīng)變隨時間發(fā)展不斷變化的流變特性，可能會使修建在軟土地基上的建(構(gòu))筑物產(chǎn)生不可忽視的工后沉降，并由此帶來安全穩(wěn)定性方面的問題。有鑒于此，本文采用試驗(yàn)與理論研究相結(jié)合的手段，從細(xì)觀角度分析影響軟土強(qiáng)度和流變特性的物質(zhì)因素和作用機(jī)理。 通過不同細(xì)觀參量組合的砂性土和軟土試樣的強(qiáng)度及流變特性試驗(yàn)，分析各細(xì)觀參量與強(qiáng)度和流變特性參數(shù)間的內(nèi)在關(guān)系，探索影響砂性土和軟土強(qiáng)度特性的作用機(jī)制，以范性流變和流質(zhì)流變解釋砂性土和軟土兩者不同的流變特性。最后，在試驗(yàn)分析的基礎(chǔ)上，探索流變相物質(zhì)形狀與分布對流變特性的影響，并通過數(shù)值模擬計算驗(yàn)證相應(yīng)結(jié)論的正確性。 本文開展的研究工作和取得的成果主要有如下幾個方面： (1)研究不同粒度成分、礦物成分和含水量的砂性土和軟土的強(qiáng)度特性�；谠囼�(yàn)分析，認(rèn)為砂性土的顆粒級配是影響其強(qiáng)度特性的重要因素；而對于軟土，不同礦物顆粒之間的吸附與摩擦、膠結(jié)作用是其強(qiáng)度特性的決定因素。此外，顆粒表面結(jié)合水膜厚度與性質(zhì)的變化將改變顆粒之間的吸附與摩擦、膠結(jié)作用機(jī)制，進(jìn)而改變其強(qiáng)度特性。 (2)采用直剪蠕變試驗(yàn)研究土體成分對流變特性的影響。試驗(yàn)結(jié)果表明，粒度成分和應(yīng)力水平對砂性土流變特性會產(chǎn)生較為顯著的影響，同時含水量在一定程度上也會影響其流變特性；軟土中的粘土礦物、氧化物、有機(jī)質(zhì)和結(jié)合水是土體產(chǎn)生流變的重要物質(zhì)因素，且都是通過顆粒表面吸附結(jié)合水來對軟土流變特性產(chǎn)生重要影響的，但不同成分對土體流變特性影響的程度有所不同；結(jié)合水性質(zhì)也會對土樣流變特性產(chǎn)生重要影響，強(qiáng)結(jié)合水對流變性的影響要比弱結(jié)合水顯著。 (3)運(yùn)用四相物質(zhì)流變理論從物質(zhì)組成上解釋砂性土和軟土的流變機(jī)理。將土體流變分為范性流變和流質(zhì)流變，砂性土流變主要受到應(yīng)力水平和粒度成分的影響，變形穩(wěn)定所需時間較短，主要表現(xiàn)為范性流變特征，而軟土流變則主要受到粘土礦物、有機(jī)質(zhì)、氧化物膠體及結(jié)合水等物質(zhì)含量的影響，變形穩(wěn)定所需時間較長，表現(xiàn)為流質(zhì)流變特征。 (4)通過室內(nèi)蠕變試驗(yàn)和數(shù)值模擬計算，分析流變相物質(zhì)形狀與分布對流變特性的影響。試驗(yàn)與數(shù)值計算結(jié)果表明，當(dāng)流變相物質(zhì)的分布較不均勻時，流變相物質(zhì)形狀與分布形式對流變特性的影響較大，但隨著流變相物質(zhì)分布均勻性逐漸增加，流變相物質(zhì)形狀與分布形式的影響逐漸減弱，流變特性逐步過渡到僅與流變相物質(zhì)性質(zhì)和比例相關(guān)，而與其形狀及分布形式無關(guān)。
[Abstract]:Soft soil is a kind of complex natural porous media widely distributed in coastal, river, lake and wetland areas. In recent years, with the development of economy and the continuous improvement of urbanization level. The development and utilization of soft soil engineering. A large number of engineering experience and research show that the deformation of soft soil needs a long time to achieve stability. May cause the building (construction) on the soft soil foundation to produce the after construction settlement which can not be ignored, and thus brings the safety and stability aspect question. In view of this, this article uses the method which the experiment and the theory research unifies. In this paper, the material factors and mechanism influencing the strength and rheological properties of soft soil are analyzed from the point of view of meso. Based on the tests of the strength and rheological properties of sand soil and soft soil samples with different meso-parameters, the relationship between the meso-parameters and the strength and rheological parameters was analyzed. This paper explores the mechanism of influencing the strength characteristics of sandy soil and soft soil, and explains the different rheological characteristics of sand soil and soft soil by norm rheology and fluid rheology. Finally, on the basis of experimental analysis. The influence of the shape and distribution of fluid phase material on rheological properties was investigated and the validity of the corresponding conclusions was verified by numerical simulation. The research work and the results obtained in this paper are mainly as follows: 1) the strength characteristics of sandy soil and soft soil with different particle size composition, mineral composition and water content are studied. Based on the experimental analysis, it is considered that the grain gradation of sandy soil is an important factor affecting its strength characteristics. For soft soil, the adsorption and friction between different mineral particles, cementation is the decisive factor of its strength characteristics. In addition, the change of the thickness and properties of water film on the surface of particles will change the adsorption and friction between particles. The cementation mechanism changes its strength characteristics. 2) the effect of soil composition on rheological properties is studied by direct shear creep test. The results show that the grain size composition and stress level have a significant effect on the rheological properties of sandy soil. At the same time, the water content will also affect its rheological characteristics to some extent. Clay minerals, oxides, organic matter and bound water in soft soil are important material factors to produce rheological properties of soft soil, and they all have important effects on rheological properties of soft soil by adsorption of water on the surface of particles. However, the degree of influence of different components on the rheological properties of soil is different. The properties of bound water also have an important effect on the rheological properties of soil samples, and the effect of strong bound water convection is more significant than that of weakly bound water. 3) the rheological mechanism of sandy soil and soft soil is explained by using the theory of four-phase material rheology. The rheology of soil is divided into normal rheology and fluid rheology. The rheology of sandy soil is mainly affected by the stress level and particle size composition, and the time required for deformation stability is relatively short, mainly showing the characteristics of normal rheology, while the rheology of soft soil is mainly affected by clay minerals and organic matter. The effect of the content of oxide colloid and bound water on the stability of deformation takes a long time and shows the rheological characteristics of fluid. 4) the influence of the shape and distribution of fluid phase material on the rheological characteristics is analyzed by indoor creep test and numerical simulation. The results of experiment and numerical calculation show that the distribution of fluid phase material is not uniform. The shape and distribution of fluid phase matter have a great influence on rheological properties, but with the increasing of the uniformity of fluid phase matter distribution, the influence of flow phase material shape and distribution form gradually weakened. The rheological properties are gradually related to the properties and proportions of rheological materials, but not to their shape and distribution.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU447;TU411

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