本文選題：浮式平臺 + 水彈簧　； 參考：《湘潭大學(xué)》2014年碩士論文

【摘要】：在深水中建設(shè)橋梁時(shí)，一般采用大直徑鉆孔灌注樁作為橋梁的墩基礎(chǔ)，在施工時(shí)，容易受到水深、洪水、通航等的限制，因此就必須設(shè)置臨時(shí)的施工平臺來排除施工干擾以及解決精確定位等問題。本文針對現(xiàn)有的橋梁深水樁基礎(chǔ)施工平臺，在大型起吊設(shè)備進(jìn)場困難、水流速度較小等條件下，，采用固定式施工平臺或采用船舶等組拼成的浮式施工平臺，已無法滿足施工需求的前提下，對采用小型浮箱組拼成的浮式施工平臺進(jìn)行研究。 首先，回顧了國內(nèi)外對深水樁基礎(chǔ)施工平臺的研究現(xiàn)狀，通過對比固定式施工平臺和浮式施工平臺的優(yōu)缺點(diǎn)，指出了對浮式施工平臺進(jìn)行深入研究的必要性。 然后，以有限元理論為基礎(chǔ)，建立整體浮式平臺的三維梁板分析模型，并將零吃水假定和水彈簧的概念引入分析當(dāng)中，以單箱在自重及偏載情況下采用理論計(jì)算、均布水彈簧剛度及不均勻水彈簧剛度的吃水深度進(jìn)行對比，分析結(jié)果表明采用不均勻水彈簧剛度進(jìn)行計(jì)算可獲得較為精確的結(jié)果。 第三，采用浮箱間剛接、鉸接及半剛接分別計(jì)算浮式平臺在各工況下的位移及應(yīng)力分布。結(jié)果表明，采用剛接、鉸接及半剛接時(shí)，其位移差別不大，其應(yīng)力則相差較大。這主要是由于上部工作平臺的縱梁將浮式平臺連為整體，使得浮式平臺縱向剛度較大。在各靜態(tài)荷載工況下，浮式平臺的各項(xiàng)指標(biāo)均符合規(guī)范要求，浮式平臺整體性能良好。 最后，對浮式平臺在移動及沖擊荷載作用下的動力響應(yīng)進(jìn)行分析。由于浮式平臺整體剛度較大及龍門吊移動速度較小，浮式平臺在移動荷載作用下考慮與不考慮附加水質(zhì)量和水動力阻尼時(shí)，其動力響應(yīng)并不明顯；而在沖擊荷載作用下，浮式平臺考慮與不考慮附加水質(zhì)量和水動力阻尼時(shí)則有較大區(qū)別。不考慮時(shí)，浮式平臺的動力響應(yīng)出現(xiàn)明顯的周期性增強(qiáng)現(xiàn)象，且其峰值也隨著體系振動逐漸衰減；在考慮時(shí)，浮式平臺的動力響應(yīng)也有較微弱的周期性增強(qiáng)現(xiàn)象。
[Abstract]:In the construction of bridges in deep water, large diameter bored cast-in-place piles are generally used as the piers foundation of bridges. In construction, they are liable to be restricted by water depth, flood, navigation, etc. Therefore, it is necessary to set up temporary construction platform to eliminate construction interference and solve the problem of accurate positioning. This paper aims at the existing bridge deep water pile foundation construction platform, under the condition that the large lifting equipment is difficult to enter the field and the flow velocity is small, the fixed construction platform or the floating construction platform composed of ships and so on are adopted. On the premise that the construction demand can not be satisfied, the floating construction platform composed of small floating box group is studied. Firstly, this paper reviews the research status of deep water pile foundation construction platform at home and abroad, and points out the necessity of further research on floating construction platform by comparing the advantages and disadvantages of fixed construction platform and floating construction platform. Then, based on the finite element theory, the three-dimensional beam-plate analysis model of the whole floating platform is established, and the zero-draught assumption and the concept of water spring are introduced into the analysis. The stiffness of uniform spring is compared with that of non-uniform spring. The results show that the stiffness of non-uniform spring can be calculated accurately. Thirdly, the displacement and stress distribution of floating platform under different working conditions are calculated by rigid connection, hinge connection and semi-rigid connection. The results show that the displacement and stress of rigid, hinged and semi-rigid joints are not different. This is mainly because the longitudinal beam of the upper platform connects the floating platform as a whole, which makes the longitudinal stiffness of the floating platform larger. Under various static load conditions, all the indexes of the floating platform meet the requirements of the specification, and the overall performance of the floating platform is good. Finally, the dynamic response of floating platform under moving and impact loads is analyzed. Because the overall stiffness of the floating platform is large and the moving speed of the gantry crane is small, the dynamic response of the floating platform is not obvious when the additional water mass and hydrodynamic damping are considered and not considered under the moving load, but under the impact load, the dynamic response of the floating platform is not obvious. The floating platform is different from that without additional water mass and hydrodynamic damping. When the dynamic response of the floating platform is not considered, the dynamic response of the floating platform appears obvious periodic enhancement phenomenon, and its peak value gradually attenuates with the system vibration, and the dynamic response of the floating platform also has the weak periodic enhancement phenomenon when considering the dynamic response of the floating platform.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U445.3

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