發(fā)布時(shí)間：2018-02-12 19:55

  本文關(guān)鍵詞： 拓展的Biot理論 雙重孔隙介質(zhì) 不均勻彈性介質(zhì) 初應(yīng)力　出處：《上海交通大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：雙重孔隙介質(zhì)理論一直是研究土動(dòng)力學(xué),地球物理學(xué)的主要手段之一。通過對地表平面波的研究有助于預(yù)測地表的內(nèi)部結(jié)構(gòu),從而發(fā)現(xiàn)埋藏在地下的自然資源;也可以用來對地震進(jìn)行分析,為降低地震造成的危害提供理論依據(jù)。通過對土層在激勵(lì)下響應(yīng)情況的研究,有助于解決地表沉降和對周邊建筑物的振動(dòng)破壞等問題。由于外部載荷的存在,溫度的變化,重力場的影響,會(huì)導(dǎo)致土層和地殼中有預(yù)應(yīng)力的存在,故研究雙重孔隙介質(zhì)動(dòng)力問題時(shí)需考慮初應(yīng)力的影響。迄今為止,盡管已有大量學(xué)者對單相介質(zhì)和單一孔隙介質(zhì)中的動(dòng)力學(xué)問題做了許多卓有成效的研究工作,但雙重孔隙介質(zhì)中的相應(yīng)問題還少見有研究,有必要進(jìn)一步的探討,尤其是受初應(yīng)力雙重孔隙介質(zhì)中表面波的傳播和動(dòng)力響應(yīng)問題。本文根據(jù)Berryman等基于拓展的Biot理論建立的雙重孔隙介質(zhì)模型,研究了覆蓋于不均勻彈性半空間上的流體飽和雙重孔隙介質(zhì)層中Love波的傳播,與平面應(yīng)變條件下下臥垂向不均勻基巖的有限厚度雙重孔隙地基在簡諧線載荷作用下的動(dòng)力響應(yīng)問題�？紤]有限厚度的流體飽和雙重孔隙地基和半無限不均勻基巖都含有初應(yīng)力。對于Love波問題,本文推導(dǎo)出Love波的頻散方程以及Love波速的上下界限,討論了孔隙率、不均勻性、各向異性和預(yù)應(yīng)力等參數(shù)對Love波傳播速度的影響。對于動(dòng)力響應(yīng)問題,本文通過引入勢函數(shù)和運(yùn)用Helmholtz原理,并利用Fourier變換求解本問題的控制微分方程,得到變換域內(nèi)應(yīng)力、位移和孔隙水壓力的一般解。再結(jié)合邊界條件,利用Fourier逆變換可以得到相應(yīng)的數(shù)值計(jì)算結(jié)果。本文的計(jì)算結(jié)果表明,孔隙介質(zhì)層基質(zhì)孔隙的孔隙率、裂隙孔隙率及基質(zhì)孔隙的孔隙率占總孔隙率的比重越大,Love波的波速越大;隨著不均勻程度的提高及各向異性系數(shù)的增大,Love波的波速增大。無論是在雙重孔隙介質(zhì)層中還是彈性半空間中,預(yù)拉應(yīng)力會(huì)使Love波的波速提高,而預(yù)壓應(yīng)力會(huì)降低Love波的波速。在簡諧激勵(lì)下,豎向位移會(huì)隨載荷頻率,有限層基質(zhì)孔隙,半平面阻尼因子和不均勻系數(shù)的增大而單調(diào)遞減。雙重孔隙介質(zhì)層和半空間所受初應(yīng)力對動(dòng)力響應(yīng)下豎向位移幅值的影響效果相同。初始拉應(yīng)力會(huì)減小豎向位移的幅值,而初始壓應(yīng)力會(huì)增大豎向位移的幅值�；|(zhì)孔隙水壓力和裂縫孔隙水壓力隨著滲透率的減小,頻率的增大而增大。頻率對裂縫孔隙水壓力的影響更大。
[Abstract]:The theory of double pore media has been one of the main methods of studying soil dynamics and geophysics. The study of surface plane waves is helpful to predict the internal structure of the surface and to find the natural resources buried underground. It can also be used to analyze earthquakes and provide a theoretical basis for reducing the damage caused by earthquakes. It is helpful to solve the problems of ground subsidence and vibration damage to surrounding buildings. Due to the existence of external load, temperature change and the influence of gravity field, the existence of prestress in soil layer and crust will be caused. So it is necessary to consider the influence of initial stress when studying the dynamic problem of dual porous medium. Although a large number of scholars have done many fruitful research work on the dynamic problem in single phase medium and single pore medium so far, However, the corresponding problems in dual porous media are rarely studied, so it is necessary to further study them. In particular, the propagation and dynamic response of surface waves in dual porous media subjected to initial stress are discussed. Based on the extended Biot theory of Berryman and others, a model of dual pore media is established in this paper. In this paper, the propagation of Love waves in a fluid saturated dual porous media layer covering an inhomogeneous elastic half-space is studied. The dynamic response of double pore foundation with finite thickness to plane strain under harmonic loading. Fluid-saturated double pore foundation and semi-infinite heterogeneous foundation with finite thickness are considered. All rocks contain initial stress. For Love wave problems, In this paper, the dispersion equation of Love wave and the upper and lower bounds of Love wave velocity are derived. The effects of porosity, inhomogeneity, anisotropy and prestress on the propagation velocity of Love wave are discussed. In this paper, by introducing the potential function and applying the Helmholtz principle and using the Fourier transform to solve the governing differential equation of this problem, the general solutions of stress, displacement and pore water pressure in the transform domain are obtained. The corresponding numerical results can be obtained by using the inverse Fourier transform. The results show that the larger the proportion of porosity, fracture porosity and matrix porosity to the total porosity is, the larger the wave velocity of the wave is. With the increase of the inhomogeneity and the anisotropy coefficient, the wave velocity of Love wave increases, both in the double porous media layer and in the elastic half-space, the pretensile stress will increase the wave velocity of the Love wave. Under harmonic excitation, the vertical displacement will change with the loading frequency and the pore size of the finite layer matrix. The effect of initial stress on the amplitude of vertical displacement under dynamic response is the same, and the initial tensile stress decreases the amplitude of vertical displacement. The initial compressive stress increases the amplitude of vertical displacement. The matrix pore water pressure and fracture pore water pressure increase with the decrease of permeability and the frequency increases.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU435

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本文編號：1506429