【摘要】：樁基礎(chǔ)作為工程實踐中的基礎(chǔ)部分以其具有的承載能力大、穩(wěn)定性好、沉降量小等特點受到高度重視。樁基礎(chǔ)的穩(wěn)定會影響到整個工程的質(zhì)量。然而由于土體之間的性質(zhì)存在著較大的差異和樁基礎(chǔ)的設(shè)計理念不同,使得樁基礎(chǔ)與土體之間的相互作用變得尤為復(fù)雜。樁-土-承臺之間的相互作用仍有諸多地方需要完善。樁-土-承臺相互作用的數(shù)值模擬分析中較多基于連續(xù)介質(zhì)力學(xué)研究方法。然而土體作為一種離散不連續(xù)介質(zhì),采用基于連續(xù)假設(shè)的分析理論弱化了土體本身所具有的顆粒離散屬性。土體顆粒之間不存在嚴(yán)格意義上的變形協(xié)調(diào),相鄰兩個土體顆粒之間的運動存在一定的差異。而離散元分析方法符合土體的這些屬性。但是當(dāng)針對結(jié)構(gòu)大,顆粒需要細分的情況,離散單元法的不足之處也表現(xiàn)的非常明顯。面對較多的顆粒時程序無法高效地完成計算。采用耦合的方法將離散元與其他數(shù)值方法結(jié)合起來,可以發(fā)揮各自的優(yōu)勢,提高計算效率,擴展離散元法的應(yīng)用范圍。本文主要的研究內(nèi)容如下：(1)簡述了樁基礎(chǔ)的作用、設(shè)計理念和常用的理論、試驗、數(shù)值模擬分析方法,同時對離散元在樁基礎(chǔ)工程中的應(yīng)用和離散-連續(xù)耦合方法的發(fā)展?fàn)顩r做了簡單的概述。(2)對離散元及分析軟件PFC3D的工作原理、基本假設(shè)、分析方法等與本文相關(guān)的方面做了簡單的介紹。(3)采用離散元分析軟件建立不同承臺尺寸、樁截面邊長、樁長的樁基礎(chǔ)模型和不同摩擦系數(shù)、孔隙度的土體模型,分別探討不同的樁基礎(chǔ)模型和土體性質(zhì)的改變對樁-土-承臺之間相互作用的影響。對模型施加豎向荷載,控制沉降速度,分析樁基礎(chǔ)在沉降過程中的樁端阻力、樁側(cè)摩阻力、承臺阻力和施加總荷載的變化規(guī)律,研究荷載在土體顆粒之間的傳遞特點,土體顆粒的運動特點,土體應(yīng)力及孔隙度的變化規(guī)律。(4)采用離散-連續(xù)耦合的方法研究樁基礎(chǔ)的受載沉降過程。
[Abstract]:As the foundation part of engineering practice, pile foundation has been attached great importance for its great bearing capacity, good stability and small settlement. The stability of pile foundation will affect the quality of the whole project. However, the interaction between pile foundation and soil is especially complicated because of the great difference of soil properties and the different design concept of pile foundation. The interaction between pile-soil-cap still needs to be improved. The numerical simulation of pile-soil-cap interaction is based on continuum mechanics. However, as a discrete discontinuous medium, the analysis theory based on continuous hypothesis weakens the discrete properties of soil particles. There is no strict deformation coordination between soil particles, and there are some differences in motion between adjacent soil particles. The discrete element analysis method accords with these properties of soil. But when the structure is large and the particles need to be subdivided, the shortcomings of the discrete element method are obvious. In the face of more particles, the program can not complete the calculation efficiently. Using the coupling method to combine the discrete element with other numerical methods can give play to their respective advantages, improve the calculation efficiency and expand the application scope of the discrete element method. The main contents of this paper are as follows: (1) the function of pile foundation, the design concept and the commonly used theories, tests, numerical simulation and analysis methods are briefly described. At the same time, the application of discrete element in pile foundation engineering and the development of discrete-time continuous coupling method are briefly summarized. (2) the working principle of discrete element and the analysis software PFC3D, the basic assumptions, are given. The analysis methods and other related aspects are briefly introduced. (3) the discrete element analysis software is used to establish the pile foundation model with different pile cap size, pile cross-section side length, pile length and soil model with different friction coefficient and porosity. The effects of different pile foundation models and soil properties on the pile-soil-cap interaction are discussed. The vertical load is applied to the model, the settlement velocity is controlled, and the variation law of pile tip resistance, pile side friction resistance, pile cap resistance and total load applied in the settlement process of pile foundation are analyzed, and the characteristics of load transfer between soil particles are studied. The movement characteristics of soil particles, the variation law of soil stress and porosity. (4) the discrete continuous coupling method is used to study the settlement process of pile foundation under load.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TU470

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