堆載作用下既有橋梁群樁基礎(chǔ)承載特性分析
發(fā)布時(shí)間：2018-09-03 11:02
【摘要】：隨著我國(guó)鐵路、公路建設(shè)規(guī)模的持續(xù)發(fā)展,鐵路、公路橋梁的總里程不斷增加,但由于施工條件和環(huán)境等各種因素的限制,經(jīng)常會(huì)出現(xiàn)天然沖填土及施工中的棄方填土在橋下樁基周圍大面積堆積的情況。堆填上荷載作用的結(jié)果主要表現(xiàn)在兩個(gè)方面,一方面使樁周上產(chǎn)生水平位移,引起橋梁樁基產(chǎn)生彎曲變形,從而造成上部結(jié)構(gòu)偏移甚至無法正常運(yùn)營(yíng)；另一方面使樁周土體進(jìn)一步固結(jié),上體與樁身發(fā)生相對(duì)位移,樁周產(chǎn)生較大的負(fù)摩阻力,進(jìn)而降低樁基的承載力并產(chǎn)生不均勻沉降。可以看出,堆載作用對(duì)橋梁樁基礎(chǔ)承載力及變形產(chǎn)生的不利影響對(duì)鐵路運(yùn)輸及人民生命財(cái)產(chǎn)安全構(gòu)成了嚴(yán)重的威脅,因此考察堆載作用下既有橋梁群樁基礎(chǔ)承載特性及變形規(guī)律,評(píng)價(jià)其是否滿足設(shè)計(jì)承載力及變形的要求是十分必要。木文在總結(jié)國(guó)內(nèi)外近年來偏載作用對(duì)橋梁樁基承載特性的影響分析的基礎(chǔ)上,由彈性理論推導(dǎo)出了在不同堆載等級(jí)、堆載距離下樁基承載力的理論計(jì)算公式;與理論計(jì)算相對(duì)應(yīng),建立了三維有限元模型,分析了隨著堆載等級(jí)及距離變化單樁和群樁樁基承載力及變形的發(fā)展規(guī)律；在此基礎(chǔ)上,建立了群樁基礎(chǔ)三維有限元固結(jié)分析模型,研究了樁基沉降及內(nèi)力隨時(shí)間的變化規(guī)律,并與現(xiàn)場(chǎng)橋梁樁基礎(chǔ)沉降實(shí)測(cè)數(shù)據(jù)進(jìn)行了對(duì)比分析,驗(yàn)證了理論分析和數(shù)值計(jì)算的正確性。本文的主要研究成果如下：(1)調(diào)研了堆載作用下橋梁樁基礎(chǔ)承載特性及變形的理論計(jì)算及分析方法,介紹了堆載作用下樁基受力特性及其復(fù)雜性,為本文的研究奠定了理論基礎(chǔ)。(2)基于彈性理論中半無限空間表面上作用一豎向集中力F時(shí),半空間內(nèi)任一點(diǎn)的應(yīng)力和位移的彈性力學(xué)解,針對(duì)應(yīng)力及位移問題求解的復(fù)雜性,借助Matlab編程構(gòu)建了相應(yīng)的計(jì)算程序,推導(dǎo)出堆載狀態(tài)下樁周土任一點(diǎn)的應(yīng)力和位移,從而推導(dǎo)出任意堆載等級(jí)、堆載距離下單樁基礎(chǔ)承載力的解析解；根據(jù)理論計(jì)算模型,建立了三維數(shù)值計(jì)算模型,研究了隨堆載等級(jí)及距離變化,單樁及群樁基礎(chǔ)的承載力及群樁效應(yīng)系數(shù)的發(fā)展規(guī)律,與理論計(jì)算進(jìn)行了對(duì)比分析,提出了不同堆載距離對(duì)應(yīng)的安全堆載等級(jí)的計(jì)算公式。(3)以大麗線深厚軟土區(qū)大區(qū)域堆載導(dǎo)致橋梁梅花樁群基礎(chǔ)病害典型工點(diǎn)為背景,建立了梅花樁群基礎(chǔ)三維有限元固結(jié)模型,研究了全堆載作用下群樁基礎(chǔ)的沉降及受力特性隨時(shí)間的變化規(guī)律。在此基礎(chǔ)上,建立了橋梁現(xiàn)場(chǎng)梁梅花樁群基礎(chǔ)及其上部結(jié)構(gòu)沉降變形自動(dòng)化監(jiān)測(cè)系統(tǒng),分析了各橋墩基礎(chǔ)沉降變形變化規(guī)律,評(píng)估了其服役狀態(tài)；為服務(wù)線路運(yùn)營(yíng)安全發(fā)揮了重要的指導(dǎo)作用。
[Abstract]:With the continuous development of railway and highway construction scale in China, the total mileage of railway and highway bridges is increasing, but due to the construction conditions and environment and other factors, Natural fill and abandoned fill are often accumulated in large area around pile foundation under bridge. On the one hand, the horizontal displacement around the pile causes the bridge pile foundation to bend and deform, which results in the displacement of the superstructure and even the normal operation of the superstructure. On the other hand, the soil around the pile is further consolidated, the upper body and the pile body have relative displacement, and the pile circumference produces greater negative friction resistance, thus reducing the bearing capacity of the pile foundation and producing uneven settlement. It can be seen that the adverse effects of heaps on the bearing capacity and deformation of the bridge pile foundation pose a serious threat to the safety of railway transportation and people's lives and property. Therefore, it is necessary to investigate the bearing characteristics and deformation law of existing bridge pile group foundation under the action of surcharge, and to evaluate whether it meets the requirements of design bearing capacity and deformation. On the basis of summarizing the influence of eccentric loads on the bearing characteristics of bridge pile foundation at home and abroad in recent years, the paper deduces the theoretical calculation formula of pile foundation bearing capacity under different heap-load grades and heap-load distance by elastic theory. Corresponding to the theoretical calculation, a three-dimensional finite element model is established, and the development law of bearing capacity and deformation of single pile and group pile foundation with the change of heaped load grade and distance is analyzed. The three-dimensional finite element consolidation analysis model of pile group foundation is established, and the variation law of pile foundation settlement and internal force with time is studied, and compared with the measured data of bridge pile foundation settlement on the spot. The correctness of theoretical analysis and numerical calculation is verified. The main research results of this paper are as follows: (1) the theoretical calculation and analysis methods of bearing characteristics and deformation of bridge pile foundation under heaped load are investigated, and the mechanical characteristics and complexity of pile foundation under surcharge are introduced. (2) based on the elastic theory, when a vertical concentrated force is applied on the surface of a semi-infinite space, the elastic solution of stress and displacement at any point in the semi-infinite space is obtained, and the complexity of solving the stress and displacement problem is discussed. With the help of Matlab programming, the corresponding calculation program is constructed, and the stress and displacement of soil around the pile at any point in the state of pile load are deduced, and the analytical solution of the bearing capacity of the pile foundation under any heaped load grade and the heap-load distance is derived, and the model is calculated according to the theoretical model. A three-dimensional numerical calculation model is established, and the development law of bearing capacity and pile group effect coefficient of single pile and pile group foundation are studied with the change of heap-load grade and distance, and compared with theoretical calculation. In this paper, the calculation formula of safety heap-load grade corresponding to different heap-load distance is put forward. (3) based on typical site of foundation disease caused by overburden in deep soft soil area of Dalian Line, a three-dimensional finite element consolidation model for foundation of Plum Blossom pile Group is established. The variation law of settlement and stress characteristics of pile group foundation with time under full surcharge is studied. On this basis, an automatic monitoring system for settlement and deformation of bridge site beam and Meihua pile group foundation and its superstructure is established, and the variation law of settlement and deformation of each pier foundation is analyzed, and its service status is evaluated. It plays an important role in guiding the operation safety of service lines.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U443.15
本文編號(hào)：2219795
[Abstract]:With the continuous development of railway and highway construction scale in China, the total mileage of railway and highway bridges is increasing, but due to the construction conditions and environment and other factors, Natural fill and abandoned fill are often accumulated in large area around pile foundation under bridge. On the one hand, the horizontal displacement around the pile causes the bridge pile foundation to bend and deform, which results in the displacement of the superstructure and even the normal operation of the superstructure. On the other hand, the soil around the pile is further consolidated, the upper body and the pile body have relative displacement, and the pile circumference produces greater negative friction resistance, thus reducing the bearing capacity of the pile foundation and producing uneven settlement. It can be seen that the adverse effects of heaps on the bearing capacity and deformation of the bridge pile foundation pose a serious threat to the safety of railway transportation and people's lives and property. Therefore, it is necessary to investigate the bearing characteristics and deformation law of existing bridge pile group foundation under the action of surcharge, and to evaluate whether it meets the requirements of design bearing capacity and deformation. On the basis of summarizing the influence of eccentric loads on the bearing characteristics of bridge pile foundation at home and abroad in recent years, the paper deduces the theoretical calculation formula of pile foundation bearing capacity under different heap-load grades and heap-load distance by elastic theory. Corresponding to the theoretical calculation, a three-dimensional finite element model is established, and the development law of bearing capacity and deformation of single pile and group pile foundation with the change of heaped load grade and distance is analyzed. The three-dimensional finite element consolidation analysis model of pile group foundation is established, and the variation law of pile foundation settlement and internal force with time is studied, and compared with the measured data of bridge pile foundation settlement on the spot. The correctness of theoretical analysis and numerical calculation is verified. The main research results of this paper are as follows: (1) the theoretical calculation and analysis methods of bearing characteristics and deformation of bridge pile foundation under heaped load are investigated, and the mechanical characteristics and complexity of pile foundation under surcharge are introduced. (2) based on the elastic theory, when a vertical concentrated force is applied on the surface of a semi-infinite space, the elastic solution of stress and displacement at any point in the semi-infinite space is obtained, and the complexity of solving the stress and displacement problem is discussed. With the help of Matlab programming, the corresponding calculation program is constructed, and the stress and displacement of soil around the pile at any point in the state of pile load are deduced, and the analytical solution of the bearing capacity of the pile foundation under any heaped load grade and the heap-load distance is derived, and the model is calculated according to the theoretical model. A three-dimensional numerical calculation model is established, and the development law of bearing capacity and pile group effect coefficient of single pile and pile group foundation are studied with the change of heap-load grade and distance, and compared with theoretical calculation. In this paper, the calculation formula of safety heap-load grade corresponding to different heap-load distance is put forward. (3) based on typical site of foundation disease caused by overburden in deep soft soil area of Dalian Line, a three-dimensional finite element consolidation model for foundation of Plum Blossom pile Group is established. The variation law of settlement and stress characteristics of pile group foundation with time under full surcharge is studied. On this basis, an automatic monitoring system for settlement and deformation of bridge site beam and Meihua pile group foundation and its superstructure is established, and the variation law of settlement and deformation of each pier foundation is analyzed, and its service status is evaluated. It plays an important role in guiding the operation safety of service lines.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U443.15
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