本文選題：2.5維有限元 + 地鐵　； 參考：《浙江大學》2013年碩士論文

【摘要】：近幾年來軌道交通的高速發(fā)展引起的環(huán)境振動和路基不均勻沉降問題日益凸顯。過大的環(huán)境振動影響了沿線居民的正常生活,以及沿線一些有精密儀器的實驗室和設(shè)備工廠,另外也可能會破壞沿線的一些不能承受過大振動的歷史性建筑；而列車的長期運營后引起的路基不均勻沉降會使振動加劇。所以軌道交通引起的振動問題和沉降問題被越來越多的學者關(guān)注。 本文首先運用已有的2.5維有限元方法,引入多層阻尼邊界,通過計算帶有一定激振頻率移動矩形荷載下土體中的振動響應(yīng),與半解析解方法進行對比,以驗證本模型在計算動靜荷載下場地振動的正確性。 之后把列車荷載考慮為移動常荷載,再加以一定的激振頻率來分析不考慮車輛和軌道耦合的情況下單輪荷載通過時和整車荷載通過時隧道結(jié)構(gòu)以及周圍土層中的振動響應(yīng)特征。為了表征這一結(jié)果,在地表和土層內(nèi)部分別選擇了若干個觀察點。分析后發(fā)現(xiàn)列車的速度以及激振頻率對場地中的振動響應(yīng)有著重要的影響。當荷載考慮為移動常荷載時,在地表上引起的豎向位移響應(yīng)范圍較窄,而當荷載附加較低激振頻率時,地表上引起的豎向位移響應(yīng)范圍較廣,如果附加的激振頻率較高時,那么地表上的豎向位移響應(yīng)范圍又會變窄。 為了較真實有效地模擬列車通過時引起的振動問題,考慮了軌道的不平順性,并把列車車體和軌道進行耦合。輪軌接觸力通過四分之一車體模型來計算,模型中軌道不平順采用單個余弦不平順。在此種模型下分析了軌道不平順的波長和幅值以及隧道壁厚和埋深對列車荷載引起的振動響應(yīng)的影響。分析后發(fā)現(xiàn)隧道壁厚對地表振動的影響較小,而隧道埋深和軌道不平順的波長和幅值對地表振動的影響跟列車速度有關(guān)。 為了評估浮置板軌道的減振效果,本文進一步建立了2.5維浮置板軌道分析模型,模型中浮置板軌道中的鋼軌和軌道板均采用歐拉梁來模擬,扣件和軌道板下鋼彈簧在沿軌道方向進行均化處理,并采用彈簧-阻尼系統(tǒng)來模擬。浮置板軌道結(jié)構(gòu)的剛度可通過與下面隧道結(jié)構(gòu)接觸的節(jié)點整合到下面有限單元中。文中首先分析了浮置板軌道的減振特性,然后分析了土層和隧道結(jié)構(gòu)參數(shù),浮置板軌道參數(shù)(鋼彈簧剛度和浮置板單位長度質(zhì)量)以及軌道不平順參數(shù)(不平順波長和幅值)對浮置板軌道減振效果的影響。 為了更能真實地考慮軌道不平順性,本文引入美國不平順軌道譜,并通過三角級數(shù)方法展開成不平順的空間分布,這樣軌道的不平順就可認為是由多個余弦不平順組成。通過對由每個余弦不平順下引起的輪軌接觸力進行疊加,可以得到實際不平順軌道下的輪軌接觸力。本文中采用此模型分析了高鐵和地鐵兩種工況,分析過程中考慮了不同的軌道平順性條件以及不同的列車速度。
[Abstract]:In recent years, the environmental vibration and uneven settlement of roadbed caused by the rapid development of rail transit have become increasingly prominent. Excessive environmental vibration affects the normal life of residents along the route, as well as some laboratories and equipment factories with precision instruments along the route, and may also destroy some historic buildings along the route that cannot withstand excessive vibration; The uneven settlement of roadbed caused by long-term operation of train will aggravate the vibration. So more and more scholars pay attention to the vibration problem and settlement problem caused by rail transit. In this paper, the existing 2.5 dimensional finite element method is used to calculate the vibration response of soil under the moving rectangular load with a certain frequency, and the results are compared with the semi-analytical method. In order to verify the correctness of the model under static and dynamic loads of the site vibration. Then the train load is considered as moving constant load, and the vibration response characteristics of tunnel structure and surrounding soil layer are analyzed without considering the coupling of vehicle and track. In order to represent this result, several observation points were selected in the surface and the soil layer respectively. It is found that the speed and exciting frequency of the train have an important influence on the vibration response in the field. When the load is considered as moving constant load, the response range of vertical displacement on the surface is narrower, but when the load is attached with lower excitation frequency, the response range of vertical displacement is wider, if the additional excitation frequency is higher, Then the response range of vertical displacement on the surface will narrow again. In order to simulate the vibration caused by train passing effectively, the irregularity of track is considered, and the train body and track are coupled. The wheel / rail contact force is calculated by the 1/4 car body model, in which the track irregularity is a single cosine irregularity. Under this model, the influence of the wavelength and amplitude of track irregularity, tunnel wall thickness and buried depth on the vibration response induced by train load is analyzed. It is found that the influence of tunnel wall thickness on surface vibration is small, while the influence of tunnel depth and the wavelength and amplitude of track irregularity on the surface vibration is related to the train speed. In order to evaluate the vibration reduction effect of floating slab track, a 2.5 dimensional analysis model of floating slab track is established in this paper. In the model, Euler beam is used to simulate the rail and track slab in the floating slab track. The steel spring under the rail plate and fastener are homogenized along the track, and the spring damping system is used to simulate them. The stiffness of the floating slab track structure can be integrated into the following finite element by the nodes in contact with the tunnel structure below. In this paper, the vibration absorption characteristics of floating slab track are analyzed, and then the parameters of soil layer and tunnel structure are analyzed. The influence of track parameters (steel spring stiffness and unit length mass of floating slab) and track irregularity (irregularity wavelength and amplitude) on the vibration reduction effect of floating slab track. In order to consider the irregularity of orbit more realistically, this paper introduces the spectrum of irregularity orbit in the United States and expands it into the spatial distribution of irregularity by means of trigonometric series method, so that the irregularity of orbit can be considered as composed of several cosine irregularity. By superposing the wheel-rail contact force caused by each cosine irregularity, the wheel-rail contact force under the actual irregularity track can be obtained. This model is used to analyze the two working conditions of high-speed rail and subway. Different conditions of track ride comfort and different train speeds are considered in the process of analysis.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU435;U211.3

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