本文選題：飽和介質(zhì)　切入點(diǎn)：三維粘彈性人工邊界　出處：《中國水利水電科學(xué)研究院》2015年碩士論文

【摘要】：強(qiáng)震作用下土壩、土體邊坡及其地基會產(chǎn)生液化失穩(wěn)問題,因此對其進(jìn)行抗震安全評價理應(yīng)將土體看作由土骨架和孔隙水兩相材料組成。動力分析不僅要給出土骨架的位移時程還要計算出孔隙水壓力的變化時程。與單相固體結(jié)構(gòu)的人工粘彈性邊界不同,對于飽和土體的人工邊界,除了要處理位移邊界條件外,還要考慮孔隙水壓力在人工邊界的傳播。本文在總結(jié)當(dāng)前國內(nèi)外人工邊界處理方法研究成果的基礎(chǔ)上,建立了具有粘彈性人工邊界的三維飽和介質(zhì)動力學(xué)虛位移原理。同時,基于有限元自動生成系統(tǒng)(FEPG),開發(fā)了具有粘彈性人工邊界的三維飽和介質(zhì)動力固結(jié)方程計算程序。利用該程序討論了沖擊荷載、突加荷載以及地震荷載作用下土體地位移、速度、加速度和孔隙水壓力的擴(kuò)散過程。主要研究內(nèi)容包括：(1)基于辛克維奇(Zienkiewicz)的基本假設(shè),認(rèn)為土是固體骨架和介質(zhì)液組成的兩相體,忽略流體中的壓縮波,以飽和介質(zhì)動力固結(jié)方程的u-p形式為基本方程。按照球面波陣面上的位移和應(yīng)力與人工邊界上的應(yīng)力和位移的等效關(guān)系,推導(dǎo)并給出了三維飽和介質(zhì)粘彈性人工邊界的邊界條件和邊界上的流量公式；(2)基于虛位移原理建立了加粘彈性人工邊界的三維飽和介質(zhì)動力固結(jié)控制方程的積分弱解形式,并對照一般粘彈性人工邊界的地震動輸入,根據(jù)有效應(yīng)力原理給出了飽和介質(zhì)粘彈性人工邊界上的地震動輸入方法；(3)根據(jù)建立的動力固結(jié)控制方程弱解形式,基于有限元自動生成系統(tǒng)編寫腳本文件,開發(fā)了三維飽和介質(zhì)粘彈性人工邊界動力計算有限元程序,通過算例證明了所建立方程的正確性和程序的可行性。本文最后對孔壓吸收邊界和介質(zhì)阻尼對計算結(jié)果的影響,以及地震波作用下的飽和地基位移和孔隙水壓擴(kuò)散進(jìn)行了研究。
[Abstract]:Under the action of strong earthquake, the soil slope and its foundation will cause liquefaction instability problem. Therefore, the seismic safety evaluation should regard soil mass as composed of soil skeleton and pore water. Dynamic analysis should not only give displacement time history of unearthed skeleton, but also calculate the time history of pore water pressure change. The artificial viscoelastic boundaries of solid structures are different. For the artificial boundary of saturated soil, in addition to the displacement boundary condition, the propagation of pore water pressure at the artificial boundary should be considered. The virtual displacement principle of three-dimensional saturated media with viscoelastic artificial boundary is established. Based on the finite element automatic generating system (FEPGN), a three-dimensional saturated medium dynamic consolidation equation calculation program with viscoelastic artificial boundary is developed. By using the program, the earth displacement and velocity under impact load, sudden addition load and earthquake load are discussed. Acceleration and pore water pressure diffusion process. The main research contents include: 1) based on the basic hypothesis of Sinkevich Zienkiewicz), the soil is considered as a two-phase body composed of solid skeleton and medium liquid, and the compression wave in fluid is ignored. Taking u-p form of dynamic consolidation equation of saturated medium as the basic equation, according to the equivalent relation between the displacement and stress on the spherical wave front and the stress and displacement on the artificial boundary, In this paper, the boundary conditions of three-dimensional viscoelastic artificial boundary and the flow rate formula on the boundary are derived and given. Based on the virtual displacement principle, the integral weak solution of the three-dimensional saturated medium dynamic consolidation control equation with viscoelastic artificial boundary is established. According to the principle of effective stress, the input method of ground motion on the artificial boundary of saturated medium is given according to the input of the general viscoelastic artificial boundary, and the weak solution of the governing equation of dynamic consolidation is established. Based on the automatic generating system of finite element, the script file is written, and the finite element program for dynamic calculation of three dimensional viscoelastic artificial boundary in saturated medium is developed. An example is given to prove the correctness of the equation and the feasibility of the program. Finally, the influence of pore pressure absorbing boundary and medium damping on the calculation results, and the displacement of saturated foundation and pore water pressure diffusion under the action of seismic wave are studied.
【學(xué)位授予單位】：中國水利水電科學(xué)研究院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU435

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