本文選題：吸力式沉箱 + 水平荷載　； 參考：《東南大學(xué)》2015年碩士論文

【摘要】：21世紀(jì)社會(huì)經(jīng)濟(jì)發(fā)展的強(qiáng)大推動(dòng)力離不開(kāi)對(duì)海洋石油資源和海上風(fēng)能的大規(guī)模開(kāi)發(fā)利用,但由于深水條件下的海洋環(huán)境與地質(zhì)條件的復(fù)雜性,傳統(tǒng)的重力式基礎(chǔ)、樁基礎(chǔ)等基礎(chǔ)形式在技術(shù)難度和施工難度上都遇到極大困難。吸力式沉箱基礎(chǔ)作為一種新型的基礎(chǔ)形式,具有適用于深水和軟弱土質(zhì)等優(yōu)點(diǎn),可能會(huì)成為海洋平臺(tái)或風(fēng)電場(chǎng)基礎(chǔ)的一個(gè)新選擇。目前,針對(duì)水平荷載作用下吸力式沉箱基礎(chǔ)承載特性研究中很少有考慮軟土流變效應(yīng)的研究現(xiàn)狀,有必要對(duì)長(zhǎng)期水平荷載作用下吸力式沉箱基礎(chǔ)承載特性展開(kāi)相關(guān)試驗(yàn)研究和理論計(jì)算分析。本文通過(guò)室內(nèi)模型試驗(yàn)和理論分析,對(duì)吸力式沉箱基礎(chǔ)在長(zhǎng)期水平荷載作用下的承載特性進(jìn)行了研究,主要內(nèi)容和結(jié)論如下：1.通過(guò)一組短期模型試驗(yàn),確定了吸力式沉箱基礎(chǔ)的極限承載力。試驗(yàn)中模型采用鋼制沉箱,其沉箱壁和頂板厚均為20mm,沉箱外直徑為500mm,高為800mm。2.采用宏細(xì)觀方法對(duì)長(zhǎng)期水平荷載作用下的半模型試驗(yàn)進(jìn)行了分析,利用PIV技術(shù)研究了吸力式沉箱基礎(chǔ)前側(cè)土體流變效應(yīng)。試驗(yàn)表明在長(zhǎng)期水平荷載作用下,模型試驗(yàn)中特征點(diǎn)的水平位移持續(xù)增加,在加載前期位移增加較快,后期增加趨勢(shì)逐漸變緩。3.通過(guò)兩組不同水平荷載作用下的長(zhǎng)期模型試驗(yàn),對(duì)吸力式沉箱基礎(chǔ)隨時(shí)間的位移變化規(guī)律與土壓力分布規(guī)律進(jìn)行了分析。隨著加載時(shí)間的持續(xù),土面水平位移、轉(zhuǎn)角以及土壓力不斷增大,前期位移增加較快,后期逐漸趨于穩(wěn)定,而土壓力沿深度方向類似呈拋物線分布。4.為考慮土體的流變效應(yīng)對(duì)基礎(chǔ)承載特性的影響,通過(guò)建立理想彈塑性p—y曲線法中的土抗力系數(shù)k與時(shí)間變量t的關(guān)系,并對(duì)沉箱基礎(chǔ)底部抵抗矩與側(cè)摩阻力的影響進(jìn)行了修正,提出了考慮土體流變效應(yīng)的吸力式沉箱基礎(chǔ)長(zhǎng)期性能分析方法。采用該方法對(duì)全模型試驗(yàn)結(jié)果進(jìn)行分析,理論計(jì)算結(jié)果與試驗(yàn)結(jié)果相差10%左右。最后結(jié)合某工程懸索橋方案的中塔吸力式沉箱基礎(chǔ)進(jìn)行計(jì)算,預(yù)測(cè)了長(zhǎng)期水平荷載作用下位移與時(shí)間的變化規(guī)律,可為工程設(shè)計(jì)提供參考。
[Abstract]:The powerful driving force of social and economic development in the 21st century cannot be separated from the large-scale exploitation and utilization of offshore oil resources and offshore wind energy. However, due to the complexity of the marine environment and geological conditions under deep-water conditions, the traditional gravity basis, Pile foundation and other foundation form meet with great difficulty in technical difficulty and construction difficulty. As a new type of foundation, suction caisson foundation has the advantages of being suitable for deep water and weak soil, and may become a new choice for offshore platform or wind farm foundation. At present, the research status of rheological effect of soft soil is seldom considered in the study of load characteristics of suction caisson foundation under horizontal load. It is necessary to study the bearing characteristics of suction caisson foundation under long term horizontal load and to carry out theoretical calculation and analysis. In this paper, the bearing characteristics of suction caisson foundation under long term horizontal load are studied by laboratory model test and theoretical analysis. The main contents and conclusions are as follows: 1. Through a group of short-term model tests, the ultimate bearing capacity of suction caisson foundation is determined. The steel caisson is used in the test, the thickness of the caisson wall and roof is 20mm, the diameter of the caisson is 500mm and the height is 800mm. 2. The semi-model test under long-term horizontal load was analyzed by macroscopical method, and the rheological effect of soil in front of suction caisson foundation was studied by PIV technique. The experimental results show that the horizontal displacement of the characteristic point in the model test increases continuously under the long-term horizontal load, increases rapidly at the early loading stage, and slows down gradually at the later stage. Based on two groups of long-term model tests under different horizontal loads, the law of displacement and earth pressure distribution of suction caisson foundation with time are analyzed. With the continuous loading time, the horizontal displacement, rotation angle and earth pressure of the soil surface increase continuously, the early displacement increases rapidly, and gradually tends to stabilize at the later stage, and the earth pressure is parabola distribution along the depth direction. In order to consider the influence of rheological effect of soil on the bearing characteristics of foundation, the relationship between soil resistance coefficient k and time variable t in the ideal elastoplastic p-y curve method is established. The influence of resistance moment and side friction on the bottom of caisson foundation is modified, and the long-term performance analysis method of suction caisson foundation considering soil rheological effect is put forward. This method is used to analyze the experimental results of the whole model, and the difference between the theoretical results and the experimental results is about 10%. Finally, combined with the calculation of the mid-tower suction caisson foundation of a suspension bridge project, the variation law of displacement and time under long-term horizontal load is predicted, which can be used as a reference for engineering design.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU476

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