發(fā)布時間：2018-07-04 09:38

  本文選題：遠場地震 + 環(huán)境振動��； 參考：《上海理工大學(xué)》2014年碩士論文

【摘要】：地震工程科學(xué)在分析地震激勵下土-結(jié)構(gòu)相互作用包括兩個不同的方面:第一,確定場地的自由場反應(yīng);第二,計算在地震環(huán)境下自由場上建有結(jié)構(gòu)后地震動的改變和實際相互作用。遠場地震和環(huán)境振動所引發(fā)的地層振動,主要是由Rayleigh波引起的。作為一種重要的結(jié)構(gòu)形式,樁基礎(chǔ)因其卓越的優(yōu)點被廣泛應(yīng)用于軟土地基中。因此,定量計算Rayleigh波作用下樁基的橫向動力響應(yīng),對樁基的工程設(shè)計具有重要的意義。當(dāng)前,關(guān)于Rayleigh波作用下樁基礎(chǔ)的橫向動力響應(yīng)問題,大多是在均質(zhì)半空間、線粘彈性和頻域內(nèi)完成的,這并不能滿意地描述Rayleigh波作用下樁基礎(chǔ)的動力學(xué)響應(yīng)。本文主要在層狀地基、遲滯非線性和時域內(nèi)研究Rayleigh波作用下樁基礎(chǔ)的橫向動力響應(yīng)。首先,需要確定Rayleigh波作用下層狀地基的自由場反應(yīng)。本文通過引入勢函數(shù)和有限元思想,推導(dǎo)了Rayleigh波在層狀地基中的特征方程,分別建立了解析法和有限元-解析法,這兩種方法各有其鮮明的優(yōu)缺點。根據(jù)特征方程的數(shù)值計算特點,在頻率-波數(shù)域(f-k域)內(nèi)應(yīng)用BISECTION算法,快速、準確地搜索Rayleigh波特征方程的根。進而得到了各種常見地基中Rayleigh波高階模態(tài)的頻散曲線,計算結(jié)果得到了現(xiàn)場實測的頻散曲線的支持。在此基礎(chǔ)上,深入研究了層狀地基中Rayleigh波頻散特性及隨深度的位移衰減特性。其次,選用BWGG模型來模擬樁側(cè)土體的遲滯非線性。通過擬合既有的試驗?zāi)Ｐ秃蛯WGG模型的每個參數(shù)的靈敏度分析,確定了每個參數(shù)有效的取值范圍。再利用室內(nèi)動三軸循環(huán)加載試驗對BWGG模型進行修正,修正后的模型更加簡潔,且能夠反映循環(huán)次數(shù)N對土體剛度和強度弱化的影響。接著,基于動力Winkler地基梁模型和BWGG模型建立了一個新的、能夠考慮各種非線性因素影響的、研究單樁橫向非線性動力響應(yīng)的簡化分析模型。采用Galerkin法對模型的動力方程進行離散,利用Newmark-β法實現(xiàn)對樁-土相互作用系統(tǒng)的時域數(shù)值解和動力非線性響應(yīng)分析,并于試驗解進行了比較,驗證了本文方法的正確性和有效性。最后,將Rayleigh波作用下自由場地的動力反應(yīng)作為邊界輸入施加到樁-土相互作用模型中,研究了單樁在Rayleigh波作用下的橫向非線性動力特性。作為工程應(yīng)用,計算了上海光源工程中單樁在Rayleigh波作用下的橫向非線性動力響應(yīng)。
[Abstract]:The analysis of soil-structure interaction under earthquake excitation in seismic engineering science includes two different aspects: first, determining the free field response of the site; second, The change of ground motion and the actual interaction after the structure of the free field are calculated in earthquake environment. The formation vibration caused by far field earthquake and ambient vibration is mainly caused by Rayleigh wave. As an important structural form, pile foundation is widely used in soft soil foundation because of its outstanding advantages. Therefore, the quantitative calculation of the lateral dynamic response of pile foundation under Rayleigh wave is of great significance to the engineering design of pile foundation. At present, the transverse dynamic response of pile foundation under Rayleigh wave is mostly completed in homogeneous half-space, linear viscoelasticity and frequency domain, which can not satisfactorily describe the dynamic response of pile foundation under Rayleigh wave. In this paper, the transverse dynamic response of pile foundation under Rayleigh wave is studied in layered foundation, hysteretic nonlinear and time-domain. First, it is necessary to determine the free field response of layered foundation under Rayleigh waves. In this paper, the characteristic equations of Rayleigh wave in layered soil are derived by introducing the potential function and finite element method. The analytical method and the finite element analytical method are established respectively. The two methods have distinct advantages and disadvantages. According to the numerical calculation characteristics of the characteristic equation, the BISECTION algorithm is used in the frequency-wavenumber domain (f-k domain) to search the roots of the Rayleigh wave characteristic equation quickly and accurately. The dispersion curves of high order modes of Rayleigh waves in various kinds of foundations are obtained, and the calculated results are supported by the measured dispersion curves in the field. On this basis, the dispersion characteristics of Rayleigh waves and the attenuation characteristics of Rayleigh waves with depth in layered soil are studied. Secondly, BWGG model is used to simulate the hysteresis nonlinearity of soil around the pile. By fitting the existing experimental model and analyzing the sensitivity of each parameter of the BWGG model, the effective value range of each parameter is determined. The BWGG model is modified by indoor dynamic triaxial cyclic loading test. The modified model is more concise and can reflect the influence of cyclic times N on soil stiffness and strength weakening. Then, based on the dynamic Winkler foundation beam model and the BWGG model, a new simplified analysis model for the lateral nonlinear dynamic response of a single pile is established, which can take into account the influence of various nonlinear factors. The Galerkin method is used to discretize the dynamic equations of the model, and the Newmark- 尾 method is used to analyze the time-domain numerical solution and the dynamic nonlinear response of pile-soil interaction system. The numerical results are compared with the experimental results, and the correctness and validity of the proposed method are verified. Finally, the dynamic response of the free site under Rayleigh wave is applied as the boundary input to the pile-soil interaction model, and the transverse nonlinear dynamic characteristics of a single pile under Rayleigh wave are studied. As an engineering application, the transverse nonlinear dynamic response of a single pile under Rayleigh wave in Shanghai Light Source Project is calculated.
【學(xué)位授予單位】：上海理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU435;TU473.1

【參考文獻】

相關(guān)博士學(xué)位論文 前1條

1 劉忠;單樁橫向非線性動力響應(yīng)簡化分析方法研究[D];湖南大學(xué);2005年

，

本文編號：2095646