本文選題：沉管隧道 + 減沉樁　； 參考：《東南大學(xué)》2015年博士論文

【摘要】：本文以國(guó)家科技支撐計(jì)劃項(xiàng)目“港珠澳大橋跨海集群工程建設(shè)技術(shù)研究與示范”研究課題——“外海厚軟基大回淤超長(zhǎng)沉管隧道設(shè)計(jì)與施工關(guān)鍵技術(shù)”(項(xiàng)目編號(hào)：2011BAG07B01)為依托,針對(duì)港珠澳大橋沉管隧道底部減沉群樁基礎(chǔ),開(kāi)展了大量文獻(xiàn)調(diào)研,采用了理論分析、室內(nèi)模型試驗(yàn)研究相結(jié)合的技術(shù)路線(xiàn),較全面的研究了沉管荷載作用下鋼管減沉群樁的承載特性。主要研究?jī)?nèi)容包括：帶墊層減沉單樁及群樁沉降、樁土荷載分擔(dān)比計(jì)算理論；基于均勻設(shè)計(jì)以及正交設(shè)計(jì)的沉管減沉樁承載性能模型試驗(yàn)及影響因素統(tǒng)計(jì)學(xué)分析；港珠澳大橋沉管隧道減沉群樁基礎(chǔ)有限元數(shù)值模擬及相關(guān)參數(shù)影響研究；本文減沉樁計(jì)算理論在依托工程實(shí)際設(shè)計(jì)方案中的運(yùn)用與分析。主要工作和結(jié)論如下：1)利用荷載傳遞法,提出了一種考慮了樁頂有無(wú)墊層對(duì)沉管隧道沉降影響的鋼管減沉單樁計(jì)算理論。對(duì)于樁頂無(wú)墊層的工況,通過(guò)預(yù)先指定荷載分擔(dān)比以明確樁土荷載,利用樁分段迭代計(jì)算求得減沉樁沉降。對(duì)于樁頂設(shè)置墊層的工況,提出了等效樁的概念,明確了樁頂與樁間土不同位置墊層的壓縮計(jì)算方法,并基于剛性沉管底不同區(qū)域沉降協(xié)調(diào),利用迭代計(jì)算得到樁土荷載分擔(dān)比和減沉樁基沉降。2)基于荷載傳遞法得到的減沉樁側(cè)摩阻力與端阻力,提出了采用彈性理論計(jì)算群樁沉降的帶墊層減沉群樁混合法。通過(guò)分離樁土彈、塑性位移,提取了樁側(cè)摩阻力彈性段,并對(duì)樁側(cè)摩阻力分布進(jìn)行等效線(xiàn)性化,然后進(jìn)行不同區(qū)域側(cè)摩阻力的Geddes應(yīng)力解的疊加,推得了減沉樁樁端平面以下土層內(nèi)任一深度處的豎向附加應(yīng)力計(jì)算公式。通過(guò)基于群樁相互作用附加沉降與基樁受力協(xié)調(diào)、沉管底不同區(qū)域位移協(xié)調(diào)的原則,得到了適用于計(jì)算帶墊層減沉群樁荷載分擔(dān)比以及沉降的迭代計(jì)算方法。3)采用均勻設(shè)計(jì)方法完成6組初步模型試驗(yàn),同時(shí)考慮了樁長(zhǎng)、樁距、墊層厚度、樁帽等多種因素,每個(gè)因素大跨度的選擇6個(gè)水平,以便覆蓋工程所有可能的取值范圍。通過(guò)試驗(yàn)數(shù)據(jù)分析和數(shù)理統(tǒng)計(jì)分析,得到多種因素共同作用下沉管沉降的基本規(guī)律,為后續(xù)模型試驗(yàn)確定參數(shù),并為工程設(shè)計(jì)方法提供參考。提出經(jīng)濟(jì)性指標(biāo)“單位面積用樁量”的概念,用于在眾多的符合減沉或承載力要求的不同樁基組合中優(yōu)選出最經(jīng)濟(jì)可行的基樁方案。通過(guò)對(duì)回歸模型的反演分析,確定出一組符合沉降控制要求的最優(yōu)減沉樁參數(shù)組合,且與試驗(yàn)結(jié)果吻合較好。4)基于混合正交試驗(yàn)設(shè)計(jì)的18組砂土中3x4群樁模型試驗(yàn),分析了沉管荷載作用下沉管、墊層、鋼管樁、地基土相互作用機(jī)理,揭示沉管底部土壓力分布、不同位置樁身軸力分布及樁土荷載分擔(dān)比等基本規(guī)律,以及它們隨沉管荷載不同的變化規(guī)律。通過(guò)對(duì)沉管沉降和復(fù)合地基承載力做極差分析、方差分析和相關(guān)分析,進(jìn)一步明確了樁距、樁長(zhǎng)、墊層厚度及樁帽對(duì)沉管沉降以及減沉樁承載特性的影響。并通過(guò)單樁承載試驗(yàn)結(jié)果擬合得出荷載傳遞函數(shù),結(jié)合本文提出的減沉樁計(jì)算理論對(duì)室內(nèi)群樁試驗(yàn)的工況進(jìn)行計(jì)算,結(jié)果與試驗(yàn)實(shí)測(cè)值進(jìn)行對(duì)比。5)對(duì)實(shí)際工程三維有限元建模分析,建議減沉樁樁長(zhǎng)采用30m左右；樁頂宜設(shè)置墊層,考慮到墊層過(guò)厚會(huì)增加沉降和成本,針對(duì)本工程建議取1m左右；在樁長(zhǎng)及墊層厚度等參數(shù)確定的情況下,若要控制基礎(chǔ)沉降,可在兼顧經(jīng)濟(jì)性的基礎(chǔ)上適當(dāng)減小樁間距,建議取用6D(D為樁間距)。6)利用本文提出的帶墊層減沉單樁和群樁計(jì)算理論,針對(duì)港珠澳大橋沉管隧道底部減沉樁基礎(chǔ)的某設(shè)計(jì)方案進(jìn)行了單樁受力、群樁相互作用等計(jì)算分析,得到了本工程合理的樁土荷載分擔(dān)比及沉管總剛度。此外,計(jì)算了減沉樁基極限承載力,并與本文提出的減沉樁承載計(jì)算理論所得的減沉樁荷載值進(jìn)行對(duì)比,為工程設(shè)計(jì)施工提供參考。綜上所述,本文針對(duì)港珠澳大橋沉管隧道減沉樁基礎(chǔ)的工程特點(diǎn),深入研究減沉樁沉降以及樁土荷載分擔(dān)比計(jì)算理論,并通過(guò)模型試驗(yàn)對(duì)相關(guān)減沉樁承載影響因素加以研究,以達(dá)到應(yīng)用于實(shí)際工程、解決實(shí)際問(wèn)題的目的。
[Abstract]:Based on the national science and technology support project "the research and demonstration of the technical research and demonstration of the construction of the harbour Zhuhai Macao Bridge across the sea cluster Engineering" - "the key technology of the design and construction of the overlong immersed tube tunnel with thick soft foundation and large back siltation" (project number: 2011BAG07B01), this paper aims at the foundation of the sinking group pile foundation at the bottom of the immersed tunnel tunnel of the Hong Kong Zhuhai Macao Bridge. A large amount of literature survey was carried out. The bearing characteristics of the pile under immersed tube loading were studied comprehensively by the theoretical analysis and the technical route combined with the indoor model test. The main research contents include the theory of calculation of the pile settlement and the load sharing ratio of pile and soil, based on the uniform design and the positive method. The bearing performance model test and the influence factor analysis of the immersed tube sinking pile, the finite element numerical simulation of the sinking group pile foundation of the immersed tunnel of Hong Kong Zhuhai Macao Bridge and the influence of related parameters; the application and analysis of the calculation theory of the settlement of the sinking pile in the actual design of the project. The main work and conclusion are as follows: 1) With the load transfer method, a calculation theory of steel pipe sinking single pile is proposed, which considers the effect of the pile top with or without the cushion on the settlement of the immersed tube tunnel. For the working condition of the pile top without the cushion, the settlement of the settlement of the pile is obtained by the specified load sharing ratio in order to clear the pile and soil load, and the pile subsection iteration calculation is used to set the cushion of the pile top. Based on the concept of equivalent pile, the compression calculation method for different position cushion of pile top and soil is clarified. Based on the settlement and coordination of different regions in the bottom of the rigid immersed tube, the lateral friction resistance and end resistance of the pile under the load transfer method are obtained by the iterative calculation and the load transfer method is used to obtain the side friction resistance and end resistance of the sinking pile based on the load transfer method. The elastic theory is put forward by using the load transfer method. In this paper, the mixing method of pile foundation subsidence reduction group pile is calculated. By separating pile soil elastic and plastic displacement, the elastic section of pile side friction is extracted, and the distribution of friction resistance of pile side is linearized. Then, the superposition of Geddes stress solution of side friction resistance in different regions is superimposed, and any depth in the soil layer below the end plane of the pile sinking pile is obtained. The formula for calculating the vertical additional stress. Based on the principle of coordination between pile group interaction and the stress of pile foundation, the principle of displacement coordination in different regions of the bottom of the immersed tube bottom, a method of calculating the load sharing ratio of pile sinking group piles and the iterative calculation method.3 for settlement is obtained. The 6 sets of preliminary model tests are completed by the uniform design method. A variety of factors such as pile length, pile distance, cushion thickness, pile cap and so on, each factor is selected 6 levels for large span, in order to cover all possible range of value of the project. Through the analysis of experimental data and mathematical statistics analysis, the basic rules of sinking pipe settlement under the joint action of a variety of factors are obtained, and the parameters are determined for the follow-up model test and the engineering design is designed. The concept of economic index "per unit area pile amount" is proposed, which is used to optimize the most economical and feasible foundation pile scheme in a large number of different pile foundation combinations which conform to the requirement of reducing or bearing capacity. It is in good agreement with the test results.4) the 3x4 group pile model test of 18 groups of sand soil based on the mixed orthogonal experimental design, analyses the interaction mechanism of immersed tube, cushion, steel pipe pile and foundation soil under the effect of immersed tube load, reveals the distribution of soil pressure at the bottom of the immersed tube, the distribution of axial force of pile body in different positions and the ratio of pile and soil load, as well as them. The influence of pile spacing, pile length, cushion thickness and pile cap on the settlement of immersed tube and bearing characteristics of sinking piles is further clarified through the difference analysis, variance analysis and correlation analysis on the settlement of immersed tube and the bearing capacity of composite foundation, and the load transfer function is fitted through the test results of single pile bearing. The calculation theory of pile reduction pile calculation in this paper is used to calculate the working conditions of indoor pile group test, and the result is compared with the test measured value.5). It is suggested that the pile length of the pile should be about 30m, and the pile top should be set up. Considering that the cushion is too thick, the settlement and cost will be increased, and the proposal of 1m for this project is taken. In the condition of determining the pile length and the thickness of the cushion, in order to control the foundation settlement, the pile spacing can be reduced properly on the basis of the economy, and it is suggested to use the 6D (D as the pile spacing).6) to use the theory of pile sinking single pile and group pile proposed in this paper, and the foundation of the foundation of the sinking pile foundation at the bottom of the immersed tunnel tunnel of Hong Kong Zhuhai Macao Bridge is given. The design scheme has carried on the calculation and analysis of single pile force, pile group interaction and so on. The reasonable load sharing ratio of pile and soil and the total stiffness of the immersed tube are obtained. In addition, the ultimate bearing capacity of the pile foundation is calculated. It is compared with the load value of the settlement pile of the pile bearing calculation theory proposed in this paper, which provides a reference for the engineering design and construction. To sum up, in view of the engineering characteristics of the sinking pile foundation of the immersed tube tunnel of the Hong Kong Zhuhai Macao Bridge, this paper deeply studies the calculation theory of settlement and load sharing ratio of the pile and soil, and studies the influence factors of the bearing capacity of the related settlement pile through the model test in order to achieve the purpose of applying to the actual engineering and solving the practical problems.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：U459.5
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本文編號(hào)：2078571