橋梁H型鋼樁抗震性能研究
發(fā)布時(shí)間：2018-08-16 07:38
【摘要】：目前,H型鋼樁基礎(chǔ),因其截面積相對(duì)較小、貫穿力強(qiáng)、對(duì)土體的擾動(dòng)小、易改變長(zhǎng)度等優(yōu)點(diǎn),而被廣泛應(yīng)用于橋梁工程中。尤其在美國(guó),有上千座橋梁采用H型鋼樁基礎(chǔ)。在正常使用階段,相對(duì)樁基所受的巨大的軸向力,水平力對(duì)H型鋼群樁基礎(chǔ)的影響似乎很小。但是,對(duì)于一些極端情況,如地震、船撞,此時(shí),H型鋼樁基礎(chǔ)將經(jīng)歷非常大的水平變形,水平力對(duì)樁基的影響就顯得至關(guān)重要。眾所周知,單樁的水平受荷反應(yīng)是群樁水平受荷分析的基礎(chǔ),而單樁的動(dòng)力特性研究往往需要其靜力性能作支撐,因而有必要研究在水平荷載作用下橋梁H型鋼單樁的相關(guān)靜力性能。基于以上所述,本文開展了橋梁H型鋼樁抗震性能試驗(yàn)和理論性研究。本文首先對(duì)六十多年來水平受荷樁的試驗(yàn)研究進(jìn)行了詳細(xì)匯總和分類,為今后的相關(guān)理論研究提供全面性的試驗(yàn)數(shù)據(jù)基礎(chǔ)。同時(shí)作者對(duì)水平受荷樁的分析方法進(jìn)行了總結(jié)和歸類,并詳細(xì)闡述了各自優(yōu)缺點(diǎn)。這些理論分析方法為將來出現(xiàn)的新型樁基礎(chǔ)在水平荷載作用下的特性研究提供了全面詳實(shí)的分析基礎(chǔ),同時(shí)也為將來進(jìn)一步研究極端動(dòng)力水平荷載下的樁基特性提供了一個(gè)全面的靜力方法分析基礎(chǔ)。而后本文制定了水平受荷H型鋼樁的試驗(yàn)規(guī)劃。試驗(yàn)分為四個(gè)單樁試驗(yàn),H型鋼樁單調(diào)強(qiáng)軸、弱軸方向水平加載試驗(yàn),以及H型鋼樁循環(huán)往復(fù)強(qiáng)軸、弱軸水平方向加載試驗(yàn)。試驗(yàn)中,H型鋼樁為模型樁,縮尺比例為1/3,采用事先預(yù)埋方式,砂土采用夯實(shí)方式填埋。從試驗(yàn)結(jié)果看出,無論是強(qiáng)軸還是弱軸加載,H型鋼樁在大變形下都具有較為穩(wěn)定的性能。在水平加載的初始階段,即小變形條件下,H鋼樁-土體的滯回曲線呈現(xiàn)捏攏狀,整體特性主要由土體所控制;而在大變形條件下,H鋼樁-土體的滯回曲線較為飽滿,其整體特性主要由H型鋼樁所控制。單調(diào)、循環(huán)往復(fù)加載試驗(yàn)中,彎矩分布形態(tài)較為相似,循環(huán)往復(fù)加載試驗(yàn)中最大彎矩所對(duì)應(yīng)的深度,要大于單調(diào)加載試驗(yàn)中的對(duì)應(yīng)深度,這種差別在強(qiáng)軸方向加載時(shí)表現(xiàn)的尤為明顯,這主要是因?yàn)檠h(huán)往復(fù)加載方式會(huì)導(dǎo)致更深的樁土空隙出現(xiàn)。強(qiáng)、弱軸方向加載下的樁身最大彎矩所對(duì)應(yīng)的位置差別較大,由于樁土相對(duì)剛度的差異,強(qiáng)軸方向的最大彎矩對(duì)應(yīng)深度要大于弱軸方向相應(yīng)深度4倍樁截面邊長(zhǎng)左右。試驗(yàn)中最大土壓力分布位置與最大彎矩對(duì)應(yīng)位置較為一致,土壓力隨加載點(diǎn)位移的曲線變化呈現(xiàn)拋物線型,土體呈現(xiàn)高度非線性。從剛度退化曲線可以看出,對(duì)于強(qiáng)軸方向循環(huán)加載試驗(yàn),其整體剛度最大值所對(duì)應(yīng)的水平位移要大于弱軸方向加載的相應(yīng)值,這主要是由于強(qiáng)軸循環(huán)加載會(huì)使砂土密實(shí)性更好,從而會(huì)使其峰值剛度所對(duì)應(yīng)的水平位移偏大。在試驗(yàn)研究的基礎(chǔ)之上,本文通過建立有限元模型來探討砂土中H型鋼樁的抗震性能。從分析結(jié)果看出,盡管API模型和Reese模型會(huì)低估樁土的抗側(cè)剛度和極限承載力,但從整體來講,兩者都能較為合理的預(yù)測(cè)水平力—位移反應(yīng)。從水平力-位移反應(yīng)和樁身彎矩沿深度分布曲線可以看出,Reese模型對(duì)地基反力模量變化系數(shù)不敏感。考慮到土體的離散性,本文對(duì)API規(guī)范中推薦的p-y曲線進(jìn)行了適當(dāng)修正。修正后的有限元模型能很好的預(yù)測(cè)樁土側(cè)向剛度和極限承載力,同時(shí)運(yùn)用修正后的有限元模型進(jìn)行了一系列的參數(shù)化分析。通過砂土摩擦角、樁頭距離地面高度、樁頭嵌固形態(tài)(自由或固結(jié))、以及軸壓比的變化,探討了其對(duì)水平受荷H型鋼樁性能的影響。最后,本文從樁土相互作用的基本方程出發(fā),引入不同軸壓比下的H型鋼樁截面彎矩-曲率關(guān)系公式,求解得到不同軸壓比下的水平受荷H型鋼樁的反應(yīng),給出了強(qiáng)、弱軸方向加載下,H型鋼樁在砂土中的位移延性系數(shù)和曲率延性系數(shù)的關(guān)系,為今后土體中H型鋼樁的抗震性能研究提供了理論性的參考。
[Abstract]:At present, H-shaped steel pile foundation is widely used in bridge engineering because of its relatively small cross-sectional area, strong penetration force, small disturbance to soil, easy to change the length and so on. Especially in the United States, there are thousands of bridges using H-shaped steel pile foundation. However, for some extreme cases, such as earthquake and ship collision, the H-shaped steel pile foundation will undergo very large horizontal deformation, and the influence of horizontal force on pile foundation is very important. It is necessary to study the related static performance of H-shaped steel single piles under horizontal loads. Based on the above, the seismic performance test and theoretical research of H-shaped steel piles are carried out in this paper. Firstly, the experimental research of horizontal loaded piles over the past sixty years is summarized and classified in detail for the future. At the same time, the author summarizes and classifies the analysis methods of the horizontal loaded piles, and elaborates their respective advantages and disadvantages. These theoretical analysis methods provide a comprehensive and detailed analysis basis for the future research on the characteristics of the new pile foundation under horizontal load. It also provides a comprehensive static analysis foundation for further study of pile foundation characteristics under extreme dynamic horizontal loads in the future. Then the test plan of H-shaped steel piles under horizontal loading is formulated. In the test, H-shaped steel piles are model piles with a scale of 1/3, pre-buried and compacted in sand. It is shown from the test results that H-shaped steel piles have relatively stable performance under large deformation, whether under strong or weak axial loading. The hysteretic curves of H-steel piles and soil are pinched, and the overall characteristics are mainly controlled by the soil. Under the condition of large deformation, the hysteretic curves of H-steel piles and soil are full, and the overall characteristics are mainly controlled by H-steel piles. The depth corresponding to the bending moment is greater than that corresponding to the monotonic loading test. This difference is especially evident when the pile is loaded in the direction of strong axis. This is mainly because the cyclic reciprocating loading will lead to deeper voids in the pile and soil. The maximum bending moment in the strong axis direction corresponds to about 4 times the length of the cross section of the pile in the weak axis direction. It can be seen from the chemical curve that the horizontal displacement corresponding to the maximum global stiffness is greater than that corresponding to the weak axial direction in the cyclic loading test. This is mainly due to the better compactness of the sand under the cyclic loading of the strong axial direction, which makes the horizontal displacement corresponding to the peak stiffness larger. The results show that although API model and Reese model can underestimate the lateral stiffness and ultimate bearing capacity of pile and soil, both of them can reasonably predict the horizontal force-displacement response as a whole. Depth distribution curves show that Reese model is insensitive to the variation coefficient of foundation reaction modulus. Considering the discreteness of soil, the p-y curve recommended in API code is corrected appropriately. The modified finite element model can predict the lateral stiffness and ultimate bearing capacity of pile and soil very well. At the same time, the modified finite element model is used to predict the lateral stiffness and ultimate bearing capacity of pile and soil. A series of parameterized analyses are carried out. The effects of sand friction angle, pile head height from the ground, pile head embedding form (free or consolidated), and axial compression ratio on the performance of H-shaped steel piles under horizontal loading are discussed. Finally, the bending of H-shaped steel piles under different axial compression ratios is introduced from the basic equation of pile-soil interaction. The moment-curvature relation formula is used to calculate the response of H-shaped steel piles under different axial compression ratios. The relationship between the displacement ductility coefficient and the curvature ductility coefficient of H-shaped steel piles in sandy soil under strong and weak axial loading is given, which provides a theoretical reference for the future study of seismic behavior of H-shaped steel piles in soil.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U442.55
，
本文編號(hào)：2185315
[Abstract]:At present, H-shaped steel pile foundation is widely used in bridge engineering because of its relatively small cross-sectional area, strong penetration force, small disturbance to soil, easy to change the length and so on. Especially in the United States, there are thousands of bridges using H-shaped steel pile foundation. However, for some extreme cases, such as earthquake and ship collision, the H-shaped steel pile foundation will undergo very large horizontal deformation, and the influence of horizontal force on pile foundation is very important. It is necessary to study the related static performance of H-shaped steel single piles under horizontal loads. Based on the above, the seismic performance test and theoretical research of H-shaped steel piles are carried out in this paper. Firstly, the experimental research of horizontal loaded piles over the past sixty years is summarized and classified in detail for the future. At the same time, the author summarizes and classifies the analysis methods of the horizontal loaded piles, and elaborates their respective advantages and disadvantages. These theoretical analysis methods provide a comprehensive and detailed analysis basis for the future research on the characteristics of the new pile foundation under horizontal load. It also provides a comprehensive static analysis foundation for further study of pile foundation characteristics under extreme dynamic horizontal loads in the future. Then the test plan of H-shaped steel piles under horizontal loading is formulated. In the test, H-shaped steel piles are model piles with a scale of 1/3, pre-buried and compacted in sand. It is shown from the test results that H-shaped steel piles have relatively stable performance under large deformation, whether under strong or weak axial loading. The hysteretic curves of H-steel piles and soil are pinched, and the overall characteristics are mainly controlled by the soil. Under the condition of large deformation, the hysteretic curves of H-steel piles and soil are full, and the overall characteristics are mainly controlled by H-steel piles. The depth corresponding to the bending moment is greater than that corresponding to the monotonic loading test. This difference is especially evident when the pile is loaded in the direction of strong axis. This is mainly because the cyclic reciprocating loading will lead to deeper voids in the pile and soil. The maximum bending moment in the strong axis direction corresponds to about 4 times the length of the cross section of the pile in the weak axis direction. It can be seen from the chemical curve that the horizontal displacement corresponding to the maximum global stiffness is greater than that corresponding to the weak axial direction in the cyclic loading test. This is mainly due to the better compactness of the sand under the cyclic loading of the strong axial direction, which makes the horizontal displacement corresponding to the peak stiffness larger. The results show that although API model and Reese model can underestimate the lateral stiffness and ultimate bearing capacity of pile and soil, both of them can reasonably predict the horizontal force-displacement response as a whole. Depth distribution curves show that Reese model is insensitive to the variation coefficient of foundation reaction modulus. Considering the discreteness of soil, the p-y curve recommended in API code is corrected appropriately. The modified finite element model can predict the lateral stiffness and ultimate bearing capacity of pile and soil very well. At the same time, the modified finite element model is used to predict the lateral stiffness and ultimate bearing capacity of pile and soil. A series of parameterized analyses are carried out. The effects of sand friction angle, pile head height from the ground, pile head embedding form (free or consolidated), and axial compression ratio on the performance of H-shaped steel piles under horizontal loading are discussed. Finally, the bending of H-shaped steel piles under different axial compression ratios is introduced from the basic equation of pile-soil interaction. The moment-curvature relation formula is used to calculate the response of H-shaped steel piles under different axial compression ratios. The relationship between the displacement ductility coefficient and the curvature ductility coefficient of H-shaped steel piles in sandy soil under strong and weak axial loading is given, which provides a theoretical reference for the future study of seismic behavior of H-shaped steel piles in soil.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U442.55
，
本文編號(hào)：2185315
本文鏈接：http://sikaile.net/kejilunwen/daoluqiaoliang/2185315.html
最近更新
教材專著
