本文關(guān)鍵詞：循環(huán)荷載下海上風(fēng)電樁基水平承載特性研究　出處：《中國海洋大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 單向循環(huán)荷載 單樁 樁身彎矩 p-y曲線 飽和粉質(zhì)土

【摘要】：海上風(fēng)電作為一種新型清潔能源，在21世紀(jì)越來越受到人們的青睞。黃河三角洲作為中國第二大中國石油基地，又具有豐富的海上風(fēng)能資源，因此在黃河三角洲地區(qū)粉質(zhì)土的地質(zhì)概況下樁基礎(chǔ)的穩(wěn)定性越來越受到關(guān)注。 由于樁基礎(chǔ)所受荷載的復(fù)雜性，以有機玻璃管模擬樁體，在飽和粉質(zhì)土地基中進行了單樁水平靜力和單向循環(huán)加載室內(nèi)模型試驗，通過應(yīng)變采集系統(tǒng)和位移計測得兩種設(shè)樁方式和加載方式下的樁身應(yīng)變和樁身位移。并通過數(shù)學(xué)運算推出靜力加載和單向循環(huán)加載下單樁的樁身彎矩、樁體位移、樁周土反力等數(shù)據(jù)。通過分析得到如下成果： （1）水平靜力加載下，對于兩種不同的設(shè)樁方式，隨著荷載的增大，樁周土的變形和樁身彎矩都增大。由于樁周土體開始產(chǎn)生塑性屈服，從而對樁的側(cè)向約束能力下降，最大樁身彎矩位置有所下降，始終處于距離泥面3至6倍樁徑，而打入樁最大樁身彎矩值較預(yù)埋樁大。 （2）水平靜力加載下，設(shè)樁方式對樁周土反力的的主要影響是，通過改變原土體應(yīng)力狀態(tài)在深度上的分布，降低了土抗力零點位置，這種效應(yīng)隨著深度的增大而減小，因此對于Y50修正值是隨著深度增大呈增大的趨勢。 （3）通過預(yù)埋樁和打入樁在靜力加載下推算的p-y曲線發(fā)現(xiàn)，對于接近泥面處的樁土綜合剛度，打入樁較預(yù)埋樁小，這種現(xiàn)象隨著深度的增大而減弱。 （4）API中軟粘土的p-y曲線模型并不適用于粉質(zhì)土，由于其對極限土抗力的計算偏保守，因此文中Y50相對于文獻中的取值較大。 （5）單向循環(huán)加載下，對于兩種設(shè)樁方式，通過擬合發(fā)現(xiàn)，幅值和峰值應(yīng)變下最大樁身彎矩之間都呈線性增大關(guān)系，而其斜率又與周期的大小相關(guān)。因此峰值應(yīng)變下最大樁身彎矩是與幅值和周期相關(guān)的函數(shù)。樁身最大彎矩的位置隨著幅值的增大向下移動，并一直處于距離泥面4至5倍樁徑處。 循環(huán)荷載的幅值與最大樁周土反力和測點位移之間依然呈正相關(guān)，隨著幅值的增大，，樁周上部土體變形增大，荷載向更深層的土體傳遞，因此土抗力零點位置也向下移動。 （6）預(yù)埋樁和打入樁的單向循環(huán)加載下，循環(huán)周期對最大彎矩、土反力最大值、測點位移的影響是復(fù)雜多變的。 （7）對于兩種設(shè)樁方式，循環(huán)次數(shù)與峰值應(yīng)變下樁身最大彎矩、土體位移之間都呈正相關(guān)，并通過擬合給出了兩種設(shè)樁方式下函數(shù)中相關(guān)參數(shù)建議值。其次由于循環(huán)弱化作用，循環(huán)次數(shù)與最大樁周土反力之間呈負相關(guān)性，并通過擬合也給出了兩種設(shè)樁方式下相關(guān)參數(shù)的取值。 （8）由兩種設(shè)樁方式下動力p-y曲線峰值變化趨勢顯示，樁周最大土抗力與循環(huán)次數(shù)之間的關(guān)系取決于一個臨界深度，在臨界深度以上最大樁周土抗力與循環(huán)次數(shù)呈負相關(guān)，而在臨界深度下兩者呈正相關(guān)。
[Abstract]:As a new clean energy, offshore wind power has been more and more popular in 21th century. The Yellow River Delta is China's second largest oil base, and has abundant offshore wind energy resources. Therefore, the stability of pile foundation is paid more and more attention under the geological condition of silty soil in the Yellow River Delta area. Due to the complexity of pile foundation load, the laboratory model tests of single pile under horizontal static and unidirectional cyclic loading were carried out in saturated silty soil foundation by using PMMA pipe to simulate pile body. The strain and displacement of pile body are obtained by strain acquisition system and displacement meter, and the bending moment of pile under static loading and unidirectional cyclic loading is deduced by mathematical calculation. The results are as follows: (1) the displacement of piles, the reaction of soil around piles, and so on. 1) under horizontal static loading, with the increase of load, the deformation of soil around pile and bending moment of pile body increase with the increase of load, and the soil around pile begins to produce plastic yield. As a result, the lateral restraint capacity of the pile is decreased, the position of the maximum bending moment of the pile body is decreased, and the maximum bending moment of the driven pile is larger than that of the embedded pile, which is 3 to 6 times of the diameter of the pile from the mud surface. 2) under horizontal static loading, the main effect of pile setting on soil reaction around pile is to reduce the 00:00 position of soil resistance by changing the distribution of stress state of original soil in depth. This effect decreases with the increase of depth, so the correction value of Y50 increases with the increase of depth. 3) through the p-y curves calculated under static loading, it is found that the pile-soil stiffness near the mud surface is smaller than that of the embedded pile, which weakens with the increase of depth. The p-y curve model of soft clay is not suitable for silty soil. Because the calculation of ultimate soil resistance is conservative, the value of Y50 in this paper is higher than that in the literature. 5) under unidirectional cyclic loading, it is found that the maximum bending moment of pile under peak strain and amplitude increases linearly. Therefore, the maximum pile bending moment under the peak strain is a function related to the amplitude and the period. The position of the maximum bending moment of the pile body moves downward with the increase of the amplitude. It has always been 4 to 5 times the diameter of the mud surface. The amplitude of the cyclic load is still positively correlated with the maximum soil reaction force around the pile and the displacement of the measuring point. With the increase of the amplitude, the deformation of the upper soil around the pile increases and the load is transferred to the deeper soil. Therefore, the position of the earth resistance at 00:00 also moves downward. 6) under the unidirectional cyclic loading of the embedded pile and the driving pile, the influence of the cycle period on the maximum bending moment, the maximum soil reaction force and the displacement of the measuring point is complex and changeable. 7) for the two kinds of pile setting methods, there is a positive correlation between the number of cycles and the maximum bending moment of the pile body and the displacement of the soil under the peak strain. By fitting, the suggested values of the relevant parameters in the function are given. Secondly, due to the weakening of the cycle, the number of cycles is negatively correlated with the maximum soil reaction around the pile. The values of related parameters under two kinds of pile setting methods are also given by fitting. According to the change trend of peak value of dynamic p-y curve under two kinds of pile setting modes, the relationship between the maximum soil resistance around pile and the number of cycles depends on a critical depth. The maximum soil resistance around the pile is negatively correlated with the number of cycles above the critical depth, but it is positively correlated with the soil resistance at the critical depth.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：P752

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