【摘要】：桶形基礎作為一種新型的海洋平臺基礎,不僅在近海油田開發(fā)中有著廣闊的應用前景,而且也能較好的應用在港口碼頭等防波堤工程中。埋置在近海淺灘地區(qū)軟黏土中的桶形基礎不僅受到上部構筑物所引起的豎向荷載(V)作用,還受到風、波浪等引起的水平荷載(H)與力矩荷載(M)的共同作用,在這三種荷載共同作用下的桶形基礎承載力特性直接關系到其在實際工程中的推廣應用。但是由于桶形基礎的特殊性,目前現(xiàn)有的承載力計算方法很難計算出其在三種荷載復合作用下的地基承載力,而地基承載力破壞包絡面方法則是研究復合加載模式下桶形基礎地基極限狀態(tài)的一種行之有效的方法。當荷載組合在破壞包絡面外時則地基處于失穩(wěn)狀態(tài),而在破壞包絡面內時則處于穩(wěn)定狀態(tài)。本文以連云港徐圩港區(qū)的單桶多隔艙基礎防波堤為背景,在將桶形基礎簡化的基礎上,運用ABAQUS大型有限元分析軟件,對軟件中土體模型進行二次開發(fā),研究了桶形基礎在復合荷載情況下的承載力包絡線。本文主要研究內容包括如下幾個方面:1.介紹南水土體本構模型的基本理論,并基于此理論對大型有限元軟件ABAQUS中的土體模型進行二次開發(fā),然后通過與已有研究成果進行對比,驗證了南水模型在分析桶形基礎承載力時的合理性與適用性,接著確定所研究桶形基礎的基本參數(shù),并建立有限元模型。2.對建立好的有限元模型采用位移控制方法進行分析,研究桶形基礎在豎向荷載(V)、水平荷載(H)與力矩荷載(M)三種荷載分量單獨作用下的失穩(wěn)破壞模式和極限承載力特性,并變動參數(shù)進行研究,得出不同桶體埋深比與不同土層相對位置情況下桶形基礎的地基極限承載力的經(jīng)驗計算關系式。3.根據(jù)第二章研究得到的在不同荷載分量作用下桶形基礎的極限承載力,采用Swipe法和常位移比法進行加載,得到桶形基礎在不同荷載組合情況下的地基承載力包絡線,同樣變動參數(shù)進行研究,分析得到不同桶體埋深比與不同土層相對位置情況下桶形基礎的破壞包絡線,并將其進行歸一化分析。4.運用常位移比加載方式,對桶形基礎在豎向荷載(V)、水平荷載(H)與力矩荷載(M)復合作用下的承載力包絡線進行分析研究,歸納得到在豎向荷載不同的情況下桶體埋深比與土層相對位置比之間的關系曲線,為桶形基礎的設計提供參考。
[Abstract]:As a new type of offshore platform foundation, bucket foundation not only has a broad application prospect in offshore oil field development, but also can be used in breakwater engineering such as port and wharf. The bucket foundation buried in soft clay in the coastal shoal area is not only affected by the vertical load (V) caused by the upper structure, but also by the interaction of the horizontal load (H) and the moment load (M) caused by wind, wave and so on. The bearing capacity of bucket foundation under these three loads is directly related to its popularization and application in practical engineering. However, due to the particularity of bucket foundation, it is very difficult for existing methods to calculate the bearing capacity of foundation under the combined action of three kinds of loads. The method of failure envelope surface is an effective method to study the limit state of bucket foundation under composite loading mode. When the load combination is outside the failure envelope plane, the foundation is in a state of instability, while in the failure envelope plane, the foundation is in a stable state. This paper takes the breakwater of single bucket and multi-compartment foundation in Xuwei Port area of Lianyungang as the background. On the basis of simplifying the bucket foundation, using ABAQUS large-scale finite element analysis software, the soil model in the software is redeveloped. The envelope of bearing capacity of bucket foundation under composite load is studied. The main contents of this paper are as follows: 1. This paper introduces the basic theory of the constitutive model of Nanshui soil mass, based on which the soil model in the large-scale finite element software ABAQUS is redeveloped, and then compared with the existing research results. The rationality and applicability of the Nanshui model in analyzing the bearing capacity of bucket foundation are verified. Then the basic parameters of the bucket foundation are determined and the finite element model is established. The displacement control method is used to analyze the established finite element model, and the failure modes and ultimate bearing capacity characteristics of bucket foundation under the three load components of vertical load (V), horizontal load (H) and moment load (M) alone are studied. The empirical formula of ultimate bearing capacity of bucket foundation with different ratio of buried depth of bucket and relative position of soil layer is obtained. According to the second chapter, the ultimate bearing capacity of bucket foundation under different load components is studied. The envelope of bucket foundation bearing capacity under different load combinations is obtained by using Swipe method and constant displacement ratio method. The same variable parameters are studied, and the failure envelope of bucket foundation is obtained under the condition of different ratio of buried depth of bucket and relative position of different soil layer, and the damage envelope of bucket foundation is analyzed by normalization. 4. In this paper, the load envelope of bucket foundation under the combination of vertical load (V), horizontal load (H) and moment load (M) is analyzed and studied by the method of constant displacement ratio loading. The relationship curve between the ratio of buried depth of bucket and the ratio of relative position of soil layer under different vertical loads is obtained, which provides a reference for the design of bucket foundation.
【學位授予單位】：江蘇科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU470

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本文編號：2293030