【摘要】：當(dāng)天然地基承載力較差，無法滿足建筑物的要求時，就必須對地基進行處理或采用樁基礎(chǔ)來提高承載能力。通過增強或置換部分土體而形成的復(fù)合地基實現(xiàn)了由天然土體和增強體共同承擔(dān)荷載，是一種較好的地基處理方式。隨著地基處理技術(shù)的提高以及復(fù)合地基理論的發(fā)展，近年來出現(xiàn)了一種新型的復(fù)合地基形式，即剛-柔性樁復(fù)合地基。 剛-柔性樁復(fù)合地基結(jié)合使用了剛性樁和柔性樁，再加上樁間土體的作用，共同來承受建筑物的荷載。土體相對較軟，承載能力小，柔性樁可以補償樁間土承載力的不足，提高原有土體的承載能力，剛性樁不僅對柔性樁起到護樁作用，，而且承受了較大的荷載并起到了控制沉降的作用。剛-柔性樁復(fù)合地基可以充分發(fā)揮各部分的承載能力以及減少工程造價，因而有著較強的應(yīng)用前景。 本文首先介紹了筏板基礎(chǔ)下剛-柔性樁復(fù)合地基的組成以及各自的作用特點，討論了荷載作用下樁、土的應(yīng)力以及荷載分擔(dān)情況，并比較分析了復(fù)合地基的復(fù)合模量的計算方法，進而求解沉降值。然后通過討論筏板的分析模式、樁土的相互作用等關(guān)系，建立了筏板基礎(chǔ)與復(fù)合地基共同作用的基本方程。為了研究在共同作用下各個組成部分參數(shù)對復(fù)合地基承載特性的影響，利用ANSYS有限元軟件建立了筏板基礎(chǔ)剛-柔性樁復(fù)合地基的模型進行計算分析。通過對比分析計算的結(jié)果數(shù)據(jù)，討論各個參數(shù)對復(fù)合地基承載特性的影響程度，并據(jù)此探討如何進行剛-柔性樁復(fù)合地基的優(yōu)化設(shè)計分析。 通過本文的研究工作得出，剛性樁模量對于沉降值影響不大但改變了應(yīng)力分布；柔性樁模量的增大減少了差異沉降，可以改善各部分的荷載分擔(dān)比；筏板基礎(chǔ)模量對沉降及應(yīng)力分布影響較小基本可以忽略，但其厚度增大提高了抗彎能力，減小了差異沉降；褥墊層的設(shè)置改善了應(yīng)力的分布，其模量的提高減小了沉降但使剛性樁承擔(dān)了更多荷載。在實際工程中可以利用這些規(guī)律，根據(jù)建筑物對承載力和沉降的要求，合理地采取布樁形式及選取參數(shù)，使這種復(fù)合地基得到更好的應(yīng)用。
[Abstract]:When the natural foundation bearing capacity is poor and the requirements of the building cannot be met, the foundation shall be treated or the pile foundation shall be used to improve the bearing capacity. The composite foundation, which is formed by strengthening or replacing part of the soil, is a kind of good foundation treatment method to bear the load jointly by the natural soil body and the reinforcement. With the improvement of the foundation treatment technology and the development of the composite foundation theory, a new type of composite foundation, that is, the rigid-flexible pile composite foundation, has appeared in recent years. The rigid pile and the flexible pile are used in combination with the rigid-flexible pile composite foundation, and the action of the soil body between the piles is combined to bear the load of the building. The soil body is relatively soft and has small bearing capacity, and the flexible pile can compensate the deficiency of the bearing capacity of the soil between the piles, improve the bearing capacity of the original soil body, The composite foundation of the rigid-flexible pile can give full play to the bearing capacity of each part and reduce the project cost, so it has a strong application In this paper, the composition of the rigid-flexible pile composite foundation under the raft foundation and its function characteristics are introduced in this paper. The stress and load sharing of the pile and soil under the load are discussed, and the calculation method of the composite modulus of the composite foundation is also analyzed. The foundation of the raft and the foundation of the composite foundation are set up through the discussion of the analysis mode of the raft and the interaction of the pile and soil. In order to study the effect of various component parameters on the characteristics of the composite foundation, the model of the foundation of the raft-plate-rigid-flexible pile composite foundation is established by using the finite element software of ANSYS. The effect of each parameter on the characteristics of the composite foundation is discussed, and the optimization of the rigid-flexible pile composite foundation is discussed. The results of this paper show that the modulus of the rigid pile does not affect the settlement value but the stress distribution is changed, the increase of the modulus of the flexible pile reduces the differential settlement, and the parts can be improved. The load-sharing ratio; the influence of the base modulus of the raft plate on the settlement and the stress distribution is small and can be neglected, but the thickness of the raft plate improves the bending resistance and reduces the differential settlement; the arrangement of the mattress layer improves the distribution of the stress, the increase of the modulus reduces the settlement, but the rigid pile More load can be used in the actual project. According to the requirements of the building to the bearing capacity and the settlement, the form of the pile and the selection of the parameters can be reasonably adopted, so that the composite foundation can be obtained
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU470

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