本文選題：大直徑鋼管樁 + 剛度衰減��； 參考：《浙江大學(xué)》2013年碩士論文

【摘要】：海上風(fēng)電機(jī)組的樁基礎(chǔ)在其正常工作的年限中,將承受來(lái)自強(qiáng)風(fēng)荷載、波浪沖擊等水平荷載的長(zhǎng)期作用,這些低頻的循環(huán)荷載將造成樁基礎(chǔ)的永久側(cè)向變形。當(dāng)樁身轉(zhuǎn)角超過(guò)0.5。,可能造成風(fēng)力發(fā)電機(jī)無(wú)法正常運(yùn)作。因此,研究風(fēng)機(jī)樁基礎(chǔ)在波浪等長(zhǎng)期水平循環(huán)荷載作用下的側(cè)向累計(jì)位移就顯得尤為重要。 目前,最普遍用于分析樁基礎(chǔ)側(cè)向變形的方法莫過(guò)于由API建議的p-y曲線(xiàn)分析法。該法所建議的p-y曲線(xiàn)是基于小口徑樁基礎(chǔ)的現(xiàn)場(chǎng)試驗(yàn)曲線(xiàn)來(lái)對(duì)樁身位移作預(yù)測(cè),但越來(lái)越多的研究表明,p-y曲線(xiàn)法會(huì)嚴(yán)重低估大直徑樁在長(zhǎng)期受荷時(shí)的累積位移。對(duì)于大直徑海上風(fēng)機(jī)樁基礎(chǔ)而言,還缺少簡(jiǎn)單有效的方法來(lái)分析其在長(zhǎng)期水平循環(huán)荷載下的變形特性。本文的主要目的就是找到一種合適的評(píng)價(jià)方法來(lái)分析大直徑鋼管樁在長(zhǎng)期水平循環(huán)荷載作用下的側(cè)向累積位移,主要工作如下： (1)研究了無(wú)粘性土在長(zhǎng)期荷載作用下的的變形規(guī)律,對(duì)各種累積塑性變形模型進(jìn)行分析比較,采用基于室內(nèi)動(dòng)三軸試驗(yàn)的剛度衰減模型來(lái)評(píng)價(jià)無(wú)粘性土的長(zhǎng)期動(dòng)力特性,并對(duì)現(xiàn)有的剛度衰減模型進(jìn)行了改進(jìn)。 (2)分析砂土室內(nèi)動(dòng)三軸試驗(yàn)的數(shù)據(jù),得到了剛度衰減模型的回歸參數(shù),然后對(duì)有限元軟件ABAQUS進(jìn)行二次開(kāi)發(fā)以實(shí)現(xiàn)土體剛度的衰減,并將數(shù)值計(jì)算的結(jié)果與室內(nèi)單元體試驗(yàn)結(jié)果進(jìn)行了對(duì)比,最后分析評(píng)價(jià)了模型各個(gè)參數(shù)對(duì)計(jì)算結(jié)果的影響。 (3)建立了大直徑單樁基礎(chǔ)的三維有限元模型,將土體剛度衰減模型嵌入其中,研究單樁基礎(chǔ)在長(zhǎng)期水平循環(huán)荷載作用下的側(cè)向位移發(fā)展情況,重點(diǎn)分析了大直徑樁的樁徑、嵌入深度、循環(huán)次數(shù)、荷載頻率及荷載大小等對(duì)單樁基礎(chǔ)水平位移的影響,得到了一些規(guī)律性的結(jié)論。并與室內(nèi)模型樁試驗(yàn)結(jié)果進(jìn)行對(duì)比,驗(yàn)證了剛度衰減模型的有效性。
[Abstract]:In the normal working life of offshore wind turbine the pile foundation will bear the long-term action of horizontal load such as strong wind load wave impact and so on. These low-frequency cyclic loads will cause permanent lateral deformation of pile foundation. When the rotation angle of the pile is greater than 0.5, the wind turbine may not work properly. Therefore, it is very important to study the lateral accumulative displacement of fan pile foundation under the action of wave and other long-term horizontal cyclic loads. At present, the most popular method for analyzing lateral deformation of pile foundation is the p-y curve analysis method recommended by API. The p-y curve proposed by the method is based on the field test curve of the small diameter pile foundation to predict the displacement of the pile body. However, more and more studies show that the p-y curve method will seriously underestimate the cumulative displacement of the large diameter pile under long-term loading. For large diameter offshore fan pile foundation, there is a lack of simple and effective method to analyze its deformation characteristics under long-term horizontal cyclic load. The main purpose of this paper is to find a suitable evaluation method to analyze the lateral cumulative displacement of large diameter steel pipe piles under long-term horizontal cyclic loading. The main works are as follows: (1) the deformation law of cohesive soil under long-term load is studied, and various cumulative plastic deformation models are analyzed and compared. The stiffness attenuation model based on indoor dynamic triaxial test is used to evaluate the long-term dynamic characteristics of cohesive soil, and the existing stiffness attenuation model is improved. (2) the data of indoor dynamic triaxial test of sandy soil are analyzed. The regression parameters of the stiffness attenuation model are obtained, and then the finite element software Abaqus is developed twice to realize the soil stiffness attenuation, and the numerical results are compared with the results of the indoor element test. Finally, the influence of various parameters of the model on the calculation results is analyzed and evaluated. (3) the three-dimensional finite element model of large diameter single pile foundation is established, and the soil stiffness attenuation model is embedded in the model. The development of lateral displacement of single pile foundation under long term horizontal cyclic load is studied. The influence of pile diameter, embedded depth, cycle number, load frequency and load on the horizontal displacement of single pile foundation is analyzed. Some regular conclusions are obtained. The validity of the stiffness attenuation model is verified by comparing with the results of indoor model pile test.
【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】：2013
【分類(lèi)號(hào)】：TU473.1

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