本文選題：移動(dòng)荷載　切入點(diǎn)：Biot理論　出處：《浙江大學(xué)》2017年碩士論文

【摘要】：鐵路高速化已成為當(dāng)今世界交通運(yùn)輸?shù)陌l(fā)展趨勢(shì),在高鐵規(guī)�？焖贁U(kuò)大的同時(shí),高鐵運(yùn)行速度也得到了極大的提高。已有文獻(xiàn)指出,當(dāng)列車低速運(yùn)行時(shí),其在地基中引起的動(dòng)力響應(yīng)較小,與按靜力方法得到的結(jié)果差距較小。然而,隨著列車運(yùn)行速度的增加,下部結(jié)構(gòu)的振動(dòng)水平以及車輛-軌道結(jié)構(gòu)的動(dòng)力相互作用都將隨之加劇,威脅列車的運(yùn)行安全。且在我國(guó)經(jīng)濟(jì)發(fā)達(dá)的東南沿海地區(qū),廣泛分布著飽和軟土地基。由于軟土中Rayleigh波的傳播速度較小,這些地區(qū)高速列車較易超過(guò)地基的Rayleigh波速而產(chǎn)生劇烈的地基振動(dòng),不僅影響鐵路的安全運(yùn)營(yíng)和旅客的舒適性,還將對(duì)周邊環(huán)境帶來(lái)不可忽視的影響。因此,非常有必要開(kāi)展對(duì)高速列車荷載作用下飽和軟土地基的動(dòng)力響應(yīng)的研究。本文首先研究了均質(zhì)飽和地基的動(dòng)力響應(yīng),基于Biot理論與歐拉-伯努利梁理論,建立了飽和多孔介質(zhì)半空間上覆單位寬度無(wú)限長(zhǎng)度梁模型。為確保在施加垂向荷載時(shí),梁與半空間之間可以緊密貼合不會(huì)脫離,在梁與半空間的界面處使用了一種改進(jìn)的光滑接觸條件。在將等效剛度的表達(dá)式由圍道積分解析得出后,計(jì)算了不同工況下的等效剛度,從而得出三種體波(P1波,P2波與S波)的Rayleigh極點(diǎn)與散布枝點(diǎn)。而后畫出了不同土體滲透系數(shù)條件下Rayleigh極點(diǎn)與分枝點(diǎn)的軌跡,研究了梁-半空間界面上連續(xù)性條件與土體滲透系數(shù)對(duì)等效剛度的影響。其次,本文將均質(zhì)飽和地基推廣為成層飽和地基,建立了一個(gè)三維成層飽和地基模型,通過(guò)在水平方向使用傅里葉變換和正交變換從而將飽和地基Biot動(dòng)力公式化為L(zhǎng)ove和Rayleigh模態(tài)方程。在豎直方向使用薄層法將地基劃分為數(shù)個(gè)單元,得到單個(gè)薄層單元的控制方程后通過(guò)組裝獲得模型總體控制方程,最終推導(dǎo)出了三維成層飽和土地基的頻域動(dòng)力Green函數(shù)。數(shù)值計(jì)算時(shí)通過(guò)將每?jī)蓪右曌饕粋�(gè)周期結(jié)構(gòu)單元,研究了 Love模態(tài)與Rayleigh模態(tài)在不同激振頻率與土體參數(shù)下的彌散特性,從而得到了波在周期飽和軟土地基中的通帶和禁帶,并研究了周期結(jié)構(gòu)單元數(shù)對(duì)通帶與禁帶分布規(guī)律的影響。最后,在第二部分中已建立的三維層狀飽和地基模型的基礎(chǔ)上建立了鐵路高架橋的三維數(shù)值模型。該模型為無(wú)碴軌道模型,其部件包括無(wú)限長(zhǎng)的鐵軌、鐵軌扣件、不連續(xù)的軌道板及其墊層和架設(shè)于無(wú)限多跨彈性支撐梁上的混凝土底座。地基模型使用了已建立的三維層狀飽和地基模型,樁則離散為歐拉-伯努利梁。使用一系列移動(dòng)簡(jiǎn)諧點(diǎn)荷載模擬了列車荷載。通過(guò)數(shù)值計(jì)算,首先研究了飽和土地基中群樁基礎(chǔ)的阻抗,其次研究了不同速度下地表振動(dòng)速度與孔壓的空間分布規(guī)律以及列車速度的變化對(duì)地表最大振動(dòng)速度與地下最大孔壓的影響,最后研究了荷載激振頻率對(duì)地基動(dòng)力響應(yīng)的影響。以上研究為鐵路高架橋引起的地基振動(dòng)提供了理論分析模型和方法,可豐富飽和土體波動(dòng)理論,對(duì)鐵路高架橋周邊建筑的設(shè)計(jì)與施工具有重要的指導(dǎo)意義。
[Abstract]:High speed railway has become the development trend of world transportation, high-speed rail in the rapid expansion of the scale at the same time, high-speed rail running speed has been greatly improved. It has been pointed out that, when the train is running at low speed, the dynamic response of the smaller caused in the foundation, according to the gap with the static method results in smaller. However, with the increase of train speed, the dynamic substructure vibration level and vehicle track structure interaction will be intensified, a threat to the safe operation of the train. And in China's economically developed southeast coastal areas, widely distributed in saturated soft soil. Because of the transmission speed of the smaller Rayleigh wave in soft soil these areas, high-speed trains more easily than Rayleigh wave velocity of the foundation caused severe ground vibration not only affects the safe operation, and the railway passenger comfort, will not bring to the surrounding environment Ignored. Therefore, it is necessary to carry out research on the power of the high-speed train load response of saturated soft soil. This paper studies the dynamic response of homogeneous saturated soil, Biot theory and Euler Bernoulli beam based on the theory of saturated porous media was established with unit width of half space infinite length beam model. Ensure the applied vertical load, between the beam and the half space can be tightly not out, at the interface in the beam and a half space using an improved smooth contact conditions. The formula of equivalent stiffness by contour integral analysis, equivalent stiffness calculation under different working conditions, so that three kinds of body waves (P1 wave, P2 wave and S wave) Rayleigh pole and branch point spread. And then draw the different permeability coefficients of soil under the condition of Rayleigh pole and branch point trajectory of beam - half space interface. The continuity conditions and soil permeability coefficient affecting equivalent stiffness. Secondly, the foundation for the promotion of homogeneous saturated layered saturated soil, a three-dimensional layered saturated soil model, by using Fourier transform and orthogonal transformation in the horizontal direction and the saturated soil Biot dynamic formula for Love and Rayleigh modal equations. Using the thin layer method in the vertical direction the foundation is divided into a plurality of units, the governing equations are obtained by assembling the single layer unit model overall control equation, we deduced the three-dimensional domain layer saturated soil dynamic Green function. Numerical calculation by each of the two layer as a periodic structure unit, dispersion characteristics study on the Love mode and the Rayleigh mode in different vibration frequency and soil parameters, thus obtained the periodic wave in saturated soft soil in the passband and stopband, and study The number of units through periodic structure influence and the band gap distribution. Finally, the foundation has been established in the second part of the three-dimensional layered soil model was established on the three-dimensional numerical model of railway viaduct. The model for ballastless track model, its components including infinite rail fastening, discontinuous rail plate and cushion and erected in the infinite multi span concrete base beam on elastic support. The foundation model uses the established three-dimensional layered saturated soil pile model, discrete Euler Bernoulli beam. The train load was simulated using a series of harmonic moving point load. By numerical calculation, firstly studies the impedance of pile group foundation of saturated soil in the medium, then the speed speed and the hole surface vibration pressure distribution and train speed variation of the maximum vibration velocity of surface and underground maximum pore pressure. Effect of sound, finally studied the response of vibration frequency on the foundation. The above research foundation for vibration induced by railway viaduct provides a theoretical model and analysis method that can enrich the soil wave theory, which has important guiding significance to the design and construction of the railway viaduct surrounding buildings.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U211;TU435

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