整体式桥台桥梁的动力特性及参数研究

提出一个模拟土体-结构非线性相互作用的模型,用于整体式桥台桥梁的动力特性分析。在此基础上建立一座整体式桥台桥梁的有限元模型,分析了土体-结构非线性相互作用和整体式桥台桥梁动力特性之间的关系,并讨论了主要参数对整体式桥台桥梁动力特性的影响。研究结果有助于认识整体式桥台桥梁的动力性能。     

温度荷载下整体式桥台桥梁试验分析

文以富裕工业园跨线桥为工程背景,通过对整体式桥台桥梁试验数据的观测与分析,系统分析了在温度荷载作用下整体式桥台桥梁的受力性能.通过实测数据的比较,得到了桥台顶纵向位移与均匀温差的变化关系,主梁控制断面的内力分别在升温温差和降温温差下的变化规律,桥台桩柱内力分别在升温温差和降温温差下的分布与变化规律.论文研究结果为整体式桥台桥梁的研究提供了参考.     

整体式桥台斜梁桥的设计与研究

整体式桥台桥梁作为一种新兴的桥梁结构形式,有许多优点,但受力性能十分复杂,给其推广应用带来了许多难题。文章探讨了整体式桥台斜梁桥设计及研究的重点和难点,介绍了桥长、斜交角的限制,以及简化计算思路,为整体式桥台斜梁桥的设计和研究提供一定的理论基础。     

简支梁桥改造为整体式桥台桥梁的实现

主要介绍了整体式桥台桥梁的发展、构造及受力特点,并介绍了美国由旧简支梁桥改造为整体式桥台桥梁的发展情况,以意大利某一跨线桥改造工程为例说明其可行性,为国内此类桥梁的改造提供经验。     

水平荷载作用下整体式桥台桥梁受力性能研究

整体式桥台桥梁近些年在国内外出现的越来越频繁,相比于传统的桥梁结构,其在提高桥梁的耐久性等方面发挥着极大的优势作用。以实际工程为背景和试验对象,对整体式桥台桥梁的受力性能进行了分析和研究,并通过与桩内应力试验实测值进行分析,得出在制动力的作用下,单侧桥台的受力相似于均匀温差下的受力。结果表明,P-y曲线法在分析整体式桥台桥梁水平荷载下的受力性能方面具有较好的可行性。     

整体式桥台无缝桥梁技术

整体式桥台无缝桥梁是将桥梁的上部结构与桥台结为整体,避免了伸缩缝桥梁常见的水侵蚀和冻害。分析了桥梁伸缩缝装置存在的问题;介绍了国内外无伸缩缝桥梁的工程实践;提出了整体式桥台无缝桥梁应用中存在的问题。     

单跨整体式桥台钢混组合梁桥设计研究

以福州某桥梁工程为例,介绍了桥梁在景观、快速建造等要求下,桥梁的总体几何布置、主梁与桥台的结构选型以及尺寸拟定,并应用有限元分析软件MIDAS CIVIL建立了空间梁格模型,分析了单跨整体式桥台钢混组合梁桥在施工阶段和使用阶段的受力情况,论证了单跨整体式桥台钢混组合梁桥设计的可行性和合理性。     

整体式桥台桥梁极限长度

以目前世界上最长的整体式桥台桥梁Isola della Scala桥为实例建立有限元模型,通过实桥动力测试对模型进行校正;提出整体式桥台桥梁极限长度的简化计算公式,并通过有限元模型验证其精确性;利用该简化计算公式预测不同限制条件下整体式桥台桥梁的极限长度。结果表明:考虑桥墩的转动能力和桥台的承载能力时,极限长度可以达到540m;考虑温度位移产生的疲劳影响时,极限长度可以达到450m;考虑桥头搭板的耐久性时,极限长度可以达到430m。     

整体式桥台后粗粒土填料力学特性的试验研究

和传统的桥相比,整体式桥的桥身与桥台之间没有支座和伸缩缝,而是刚性连接为一体,从而能极大地节省长期运营成本,并具有更好的抗震性能,值得大力推广。但是由于季节性温度波动导致桥身长度变化,桥台随之发生循环位移,桥台后土体也就受到循环加载作用。土压力的变化趋势,以及其最终的大小及分布规律,成为整体式桥台设计的关键因素。本项研究首先对整体式桥台后面土体的受力特点进行了分析,并在此基础上成功研制水平小应变控制循环加载应力路径试验系统。通过对不同密度的砂试件进行水平小应变循环加载试验,发现无论是松砂还是密砂在循环加载过程中,其水平土压力均持续增加,并迫近被动土压力;试件的刚度和机动摩擦角也持续增加。最后,根据试验结果对整体式桥台的设计提出了建议。     

整体式桥台桥梁细部构造措施

以富裕工业园分离立交桥为工程背景,结合整体式桥台桥梁的受力特点,探讨了整体式桥台、台后填土及搭板的构造措施。台帽及台柱身外包PE15Ⅲ型高压聚乙烯泡沫塑料,能减小台后土体因桥台移动而产生的变形,减小升温作用下台后土压力对结构的不利影响。同时,也有效防止降温时台与台后填土间出现缝隙;桥头搭板采用分段的形式可有效释放结构的温度变形。利用具有高粘弹性的橡胶改性沥青填充材料作为变形缝的填料,既能方便施工、缩短工期,又能保证接缝质量,使接缝更加平顺。本文的构造措施为整体式桥台桥梁的细部设计提供参考。     

Mitigation of seasonal temperature change-induced problems with integral bridge abutments using EPS foam and geogrid

Expansion of bridge girders in summer moves integral bridge abutments toward backfill, causing high lateral earth pressures behind the abutment. Some backfill material slumps downward and toward the abutment when the abutment moves away from the backfill due to bridge girder contraction in winter. Placement of geogrids within the backfill can increase stability of the backfill while placement of compressible inclusions (e.g., Expanded Polystyrene (EPS) foam) can reduce lateral earth pressures behind the abutment caused by bridge girder expansion. In this study, six physical model tests were conducted with 30 abutment top movement cycles due to simulated seasonal temperature changes to study the performance of integral bridge abutments with different mitigation measures. The test results showed that geogrid reinforcements caused higher maximum lateral earth pressures at the same abutment movement, but geogrids with wrap-around facing significantly reduced the backfill surface settlements. The combination of the EPS foam and geogrids could minimize lateral earth pressure increase and backfill settlement. The EPS foam reduced the abutment toe outward movement when the abutment top was pushed against the backfill; however, the mitigation effects by the EPS foam was limited due to its small thickness and relatively high elastic modulus in this study.     

桥台台背土压力试验研究

高速铁路桥台台后填土从填料选择、施工控制、质量监测等方面均不同于常规铁路,但是对桥台台背土压力研究并不多见,再加上影响土压力的因素比较复杂,目前的土压力理论还难以准确地反映土压力分布的实际情况。基于此,结合现场试验对高速铁路桥台台背土压力进行长时间观测,根据实测结果分析土压力随时间的变化,土压力随填土高度变化以及填土完成后台背土压力的大小和分布情况。分析结果表明,台背土压力沿桥台深度方向呈非线性分布,土压力随着距离桥台顶部距离的增大而增加,但到达一定深度后随深度的增大土压力反而减小;土压力合力作用点要比理论上的土压力合力作用点有所上移,在0.41倍填土高度处。     

加筋土桥台台背土压力的试验研究

为了对比在桥台填土施工中,铺设土工格栅对减小桥台土压力的作用,在宁淮高速公路东一道跨线桥桥台填土施工中,东侧桥台填土中未铺设土工格栅,西侧桥台填土中铺设土工格栅,对其桥台台背土压力进行长时间观测,分析了土压力随时间的变化、土压力随填土高度的变化以及填土完成后土压力的大小与分布情况。分析结果表明,台背土压力沿桥台深度方向呈非线性分布;土压力随着至桥台顶部距离的增大而增加,但到达一定深度后,随着深度的增加,土压力反而减小;铺设土工格栅能明显降低桥台台背的土压力。     

考虑台后不平衡土压力下整体桥H型钢桩基-土相互作用内力计算方法

在台后填土作用下整体式桥台-H型钢桩-土相互作用和大不平衡土压力下(台后土表面均布荷载增大了3.81 kPa)整体式桥台-H型钢桩-土相互作用拟静力试验研究的基础上,提出了考虑台后不平衡土压力下整体桥桩基-土相互作用的内力计算方法,计算了整体桥台底弯矩和剪力以及桩身弯矩和剪力,并与现有的台后土压力理论和桥梁规范的计算值进行比较。结果表明:正向加载时,采用现有的台后土压力理论和桥梁规范计算得到的台底弯矩和剪力以及桩身弯矩和剪力均与试验结果存在较大偏差; 采用黄-林法可较准确地计算AHP模型的台底弯矩和剪力以及桩身弯矩和剪力; 对于LAHP模型,试验值均与各理论计算值相差较大; 正向加载时,随着位移荷载的增加,AHP和LAHP模型的台底和桩身弯矩均逐渐增大; 台后堆载(大不平衡土压力)对整体桥台底剪力和弯矩以及桩身的剪力和弯矩产生较大的影响,LAHP模型的台底和桩身弯矩整体上均大于AHP模型的,而LAHP模型的台底剪力小于AHP模型的,桩身剪力大于AHP模型的。     

设置EPS柔性垫层的刚性挡土墙土压力研究

建立有限差分数值模型对设置EPS(发泡聚苯乙烯)柔性垫层的刚性挡土墙的土压力进行研究,分别对挡土墙后填土的静止、主动及被动三种位移状态进行了研究,并对不同挡土墙位移时EPS垫层减小土压力的效果进行了分析。研究结果表明:EPS对主动状态所需要的位移影响较小。静止–主动状态时,EPS减小土压力的效果随着位移的增大而减弱;静止–被动状态时,EPS减小土压力的效果随着位移的增大先增强后减弱。     

回填EPS混合土的防滑悬臂式挡墙地震稳定性分析

以一种带防滑齿的"T"型悬臂式挡土墙为对象,采用振动台模型试验揭示了分别回填EPS混合土和天然南京细砂时的挡墙地震稳定性特征。分析并比较了墙–土体系的地震反应以及墙背动土压力分布,重点讨论了试验的防滑悬臂式挡墙位移模式以及回填土性质对墙背动土推力的影响。试验结果表明,回填EPS混合土时,填土地表加速度反应相对更小。回填土的动土推力对墙体转动位移的贡献随激励峰值的增大而增大;墙–土惯性相互作用效应与回填土的动力变形模式密切相关。两种回填料下的墙背动土压力分布形态具有显著差异;砂土–挡墙体系的动土推力与地表峰值加速度间趋向非线性关系,作用点接近2/3墙高。回填EPS混合土时两者更接近线性关系,且动土推力作用点接近1/3墙高。两种体系的动土推力作用点随地表峰值加速度增大均略有下移。基于试验结果与几种经典的解析方法预测结果比较,给出了EPS混合土柔性挡墙抗震分析的几点建议。     

Study of lateral earth pressures on nonyielding retaining walls with deformable geofoam inclusions

This paper proposes a method to predict the lateral earth pressures on nonyielding retaining walls with geofoam inclusions. The previous study of the lateral stress-strain relation of the backfill was extended, and the solution was derived by the iterative method. The proposed solution could be applied without the known value of the compression of the geofoam inclusions. Model tests for nonyielding retaining walls with expanded polystyrene (EPS) geofoam were also conducted to investigate lateral earth pressures. The accuracy of the proposed solution was verified by comparison to test data in the absence of surface loading. The proposed solution was also validated by a previous study of laboratory-scale model tests with surface loading as well as numerical simulations for field-scale applications with a vehicle load. Furthermore, the effect of the density and thickness of EPS on the reduction of lateral earth pressures was discussed, and appropriate design parameters of EPS were suggested for nonyielding retaining walls with EPS geofoam.     

Lateral earth pressure behind an integral abutment

Integral abutment bridges have gained increasing attention in the past few decades. They provide a cost-effective solution to the high maintenance expenses associated with the joints and bearings found in conventional bridges. This paper describes the observed behaviour of granular soil backfill retained behind an integral abutment subjected to cyclic loading. Significant pressure build-up was observed in the soil behind the abutment in most locations. The pressure build-up is attributed to several mechanisms such as sand particle flow and densification due to cyclic loading, and the shearing of dense sand during bridge expansion. Therefore, the applicability of using a linear soil pressure distribution assumed by the classical theories in designing the integral abutment system is discussed. Furthermore, the vertical and lateral distribution of the soil pressure behind the abutment has also been analysed. Results from the data measured show that bridge skew resulted in bigger soil pressures at the obtuse side of the abutment compared to the acute. The conclusions of this paper highlight several new design aspects, which are usually overlooked by the common design methodologies of integral abutments, that more accurately predict the vertical and lateral variation in the soil pressure behind abutments.     

公路土方路基施工要点

从土方开挖、路堤填筑、构造物台背回填、软土地基路基施工等方面介绍了公路土方路基施工的施工要点，从而提高公路工程土方路基施工质量，保证工程整体质量。     

Investigation of soil-geosynthetic-structure interaction associated with induced trench installation

The design of subsurface structures associated with transportation and other underground facilities, such as buried pipes and culverts, requires an understanding of soil-structure interaction. Earth loads on these structures are known to be dependent on the installation conditions. To reduce earth pressures acting on buried structures installed under high embankments, the induced trench method has been recommended and applied in practice for several decades. It involves the installation of a compressible material (e.g. EPS geofoam blocks) immediately above the buried structure to mobilize shear strength in the backfill material. A first step towards understanding this complex soil-geosynthetic-structure interaction and accurately modeling the load transfer mechanism is choosing a suitable material model for the geofoam that is capable of simulating compressive testing results. In this study, an experimental investigation is conducted to measure the changes in contact pressure on the walls of a rigid structure buried in granular backfill with an overlying geofoam layer. Validated using the experimental results, finite element analysis is then performed and used to study the role of geofoam density, thickness and location on the load transferred to the buried structure. Conclusions are made regarding the effect of modeling EPS inclusion as a non-linear material and the role of EPS configuration on the earth pressure distribution around the buried structure.