【摘要】：隨著高速鐵路的發(fā)展,橋梁結(jié)構(gòu)得到了廣泛應(yīng)用。高速鐵路橋梁與一般鐵路橋梁相比,其橫橋向剪跨比較小,有可能伴隨剪切破壞。由于高速鐵路橋梁設(shè)計(jì)主要受剛度控制,因此通過(guò)增大橋墩截面的尺寸,使其屈服強(qiáng)度增大從而提高其剛度。此設(shè)計(jì)在地震作用下,可能造成橋墩在橫橋向的抗剪能力高于樁基礎(chǔ),而在強(qiáng)震作用下,無(wú)法保證塑性鉸只出現(xiàn)在墩底,樁基礎(chǔ)會(huì)先進(jìn)入塑性狀態(tài)而發(fā)生破壞。由于現(xiàn)行規(guī)范未考慮樁基在強(qiáng)震作用下的屈服破壞,因此本文主要對(duì)橋墩在橫向地震作用下的破壞機(jī)理、單樁的破壞模式以及群樁結(jié)構(gòu)的抗震穩(wěn)定性評(píng)估方法進(jìn)行了研究。 本文以京滬高鐵沿線簡(jiǎn)支梁橋橋墩為試驗(yàn)原型,設(shè)計(jì)了2個(gè)縮尺比為1／5的橋墩模型,對(duì)橋墩橫橋向進(jìn)行了低周期反復(fù)荷載試驗(yàn),主要研究?jī)蓚�(gè)橋墩的破壞機(jī)理,計(jì)算橋墩模型的位移延性,骨架曲線并與SAP2000數(shù)值模擬結(jié)果進(jìn)行對(duì)比,驗(yàn)證有限元分析的可行性,分析橋墩破壞模式,并對(duì)橋墩模型的抗剪能力進(jìn)行驗(yàn)算,為進(jìn)一步研究樁基的抗震性能提供依據(jù)。 應(yīng)用Pushover分析方法對(duì)單樁的破壞機(jī)制及影響因素進(jìn)行了研究。樁基采用分布塑性鉸單元模擬,樁土相互作用采用p-y曲線法模擬。采用高速鐵路橋梁常用的兩種直徑(1.25m和1.5m)單樁進(jìn)行分析,并選取直徑1.5m的單樁改變其土參數(shù),得到不同土參數(shù)對(duì)結(jié)構(gòu)的影響程度。 群樁部分比較上部結(jié)構(gòu)、群樁基礎(chǔ)和整體結(jié)構(gòu)在順橋向和橫橋向的抗震能力,得到不同方向整體破壞形態(tài),并基于折減系數(shù)譜對(duì)其穩(wěn)定水平進(jìn)行評(píng)估。在考慮群樁效應(yīng)的基礎(chǔ)上,對(duì)五組群樁基礎(chǔ)施加Pushover水平荷載,得到樁基破壞基本形式,樁頂與承臺(tái)連接處為抗震設(shè)計(jì)重點(diǎn)考慮部分。 本文通過(guò)對(duì)高速鐵路橋梁地震作用下樁基失效機(jī)制的研究,得到橋梁樁基在地震作用下的危險(xiǎn)區(qū)域以及不同地震作用方向下橋梁樁基的破壞形式,這對(duì)完善國(guó)內(nèi)樁基抗震設(shè)計(jì)起到了指引作用。
[Abstract]:With the development of high speed railway, the bridge structure has been widely used. Compared with the general railway bridge, the high speed railway bridge is smaller than the general railway bridge, and it may be accompanied by shear failure. As the design of the high-speed railway bridge is mainly controlled by the stiffness, the size of the pier section is increased to increase its yield strength and improve its stiffness. Under the action of earthquake, the shear ability of the pier may be higher than that of the pile foundation. Under the action of strong earthquake, the plastic hinge can not be guaranteed only at the bottom of the pier, and the pile foundation will be damaged in the advanced plastic state. The failure mechanism of single pile under transverse earthquake, the failure mode of single pile and the evaluation method of seismic stability of pile group structure are studied.
Taking the pier of simple supported beam bridge along Beijing-Shanghai high-speed railway as experimental prototype, 2 pier models with scale ratio of 1 / 5 are designed. Low cyclic cyclic loading tests on bridge piers are carried out. The failure mechanism of two pier is mainly studied. The displacement ductility of the pier model is calculated, and the skeleton curve is compared with the results of SAP2000 numerical simulation. The feasibility of the finite element analysis is used to analyze the failure mode of the pier and to check the shear capacity of the pier model, which provides the basis for the further study of the seismic performance of the pile foundation.
The failure mechanism and influence factors of single pile are studied by Pushover method. The pile foundation is simulated with distributed plastic hinge unit. The interaction of pile and soil is simulated by p-y curve method. Two kinds of diameter (1.25m and 1.5m) single pile used in high speed railway bridge are analyzed, and the single pile with diameter 1.5m is selected to change its soil parameters. The influence of the same soil parameters on the structure.
The group pile part is compared with the upper structure, the pile group foundation and the whole structure are in different direction as a whole, and the stability level is evaluated in different directions. Based on the group pile effect, the Pushover horizontal load is applied to the five groups of group pile foundations to get the basic form of the pile foundation failure. The connection between pile top and pile cap is the key part of aseismic design.
Through the study of the failure mechanism of the pile foundation under the earthquake action of the high speed railway bridge, the damage form of the bridge pile foundation under the earthquake action and the different direction of the earthquake action is obtained. This plays a guiding role in improving the seismic design of the domestic pile foundation.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U442.55;U443.15

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