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.     

整体式桥台桥梁台后土压力的季节性变化研究

建立了整体式桥台与土共同作用的有限元模型,计算分析了季节性温度变化下台后土压力的分布曲线.以三跨连续混凝土板桥为工程实例,提出并验证台后设置EPS压缩层和置换轻填土两种方案,同时配合台后土体加筋,为整体式桥台设计提供理论依据.     

Study of the behavior of mechanically stabilized earth (MSE) walls subjected to differential settlements

The limit equilibrium (LE) analysis has been used to design MSE walls. Presumably, the deflection of MSE walls can be limited to an acceptable range by ensuring sufficient factors of safety (FOSs) for both external and internal stabilities. However, unexpected ground movements, such as movements induced by excavations, volume changes of expansive soils, collapse of sinkholes, and consolidations of underlying soils, can induce excessive differential settlements that may influence both the stability and the serviceability of MSE walls. In this study, a numerical model, which was calibrated by triaxial tests and further by a specially-designed MSE wall tests, investigated the behavior of an MSE wall as well as the influence of various factors on the performance of the MSE wall when the wall facing settled relatively to the reinforced zone. The numerical results showed that the differential settlement would cause substantial vertical and horizontal movements for the MSE wall, as well as an increase in lateral earth pressure and geosynthetic reinforcement strain. The maximum horizontal movement and increase of the lateral earth pressure occurred at about 1.0 m above the toe. The differential settlement resulted in a critical plane that coincided with the plane of 45°+?/2. The maximum increase of the strain for each geogrid layer occurred in that plane, and the bottom layer had the greatest strain increase among all layers of reinforcement. The study further indicated that the surcharge, backfill friction angle, tensile stiffness of geogrid, reinforcement length and MSE wall height had noticeable influences on horizontal and vertical movements, and strain in geosynthetics. According to the results, the MSE wall that had a higher factor of safety would have less movements and geosynthetic strain increase. In contrast, only the friction angle, tensile stiffness and MSE wall height showed some degree of influence on the lateral earth pressure due to differential settlements.     

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。     

高填涵洞采用EPS泡沫塑料减小埋涵土压力

通过具体涵洞施工实践，分析了高填涵洞采用EPS泡沫塑料减小埋涵土压力的原理，介绍了其施工过程及控制要点，总结了其使用效果，指出了今后该技术的研究方向。     

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。     

不平衡土压力对整体式桥台-H型钢桩-土体系力学性能影响试验

为研究不平衡土压力对整体式桥台-H型钢桩-土体系力学性能的影响,在已开展的不平衡土压力下整体式桥台-H型钢桩-土相互作用拟静力试验研究基础上,进一步开展了更大不平衡土压力(台后土表面均布荷载增大了3.81 kPa)下整体式桥台-H型钢桩-土相互作用拟静力试验研究,对比分析了更大不平衡土压力对桩身水平变形、桩侧土压力、应变和弯矩等方面的影响。结果表明:在试验条件下,更大不平衡土压力对桩身水平变形、土抗力、应变和弯矩的分布规律无影响; 正向加载时,更大不平衡土压力使得桩身累积变形的位置更深,桩侧最大土抗力和桩身弯矩增大; 负向加载时,更大不平衡土压力也使得桩身累积变形的位置更深和弯矩增大; 正向加载时,更大不平衡土压力使得累积变形减小,负向加载时则相反; 正向加载时LAHP模型的桩侧土抗力、应变和弯矩显著大于负向加载时的,正向加载时的最大桩侧土抗力和弯矩分别为负向加载时的2.2倍和2.1倍。     

用土压力增量比分析加筋对桥台土压力的影响

在宁淮高速公路东一道跨线桥桥台填土施工中,为了研究加筋对减小桥台土压力的影响,进行了现场试验。通过试验得出,桥台土压力沿桥台高度的分布并非光滑的二次曲线,而是不规则的S型曲线。为了消除施工现场各种因素对测试精度的影响,查找测量误差的原因,提出用土压力增量百分比ξ来表示土压力随填土高度增加的变化,以达到反映土压力变化趋势的目的。     

EPS材料在软基桥台加固中的应用

以广东某软基桥台为例,通过对桥台的病害成因以及EPS材料特性的分析,提出了可行的病害解决方案和施工方法,解决了软土地区高填土桥台常见的病害问题,避免了桥头跳车的发生。     

某桥台位移倾斜的原因分析与建议

通过某桥台的位移倾斜的原因分析 ,提出加固方案及在设计与施工中的一些建议。     

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。     

高压旋喷技术在桥台加固中的应用

以太旧高速公路龙门5号桥桥台加固治理工程为例，分析了水泥混凝土路面脱空的原因及对路面的影响，提出了高压旋喷桩的处理技术措施，并对其加固治理效果进行了阐述。     

无外露穿墙螺栓重力式桥台模板加固技术

简单介绍了如何采用14a号槽钢桁架进行钢筋混凝土重力式桥台模板加固,具体阐述了该技术的施工方法,从而使重力式桥台外露部分无穿墙螺栓,确保重力式桥台的混凝土外观质量,同时为重力式桥台施工提供了实践经验。     

聚乙烯检查井埋地实验及数据分析

本文简述了两个聚乙烯检查井埋地实验的基本情况和实验基础资料,整理出了埋地实验的实验数据,并对实验数据进行分析,总结了检查井埋地后的变形和井体上土侧压力的特点,供工程技术人员参考。     

Applied bearing pressure beneath a reinforced soil foundation used in a geosynthetic reinforced soil integrated bridge system

Geosynthetic reinforced soil integrated bridge system (GRS-IBS) design guidelines recommend the use of a reinforced soil foundation (RSF) to support the dead loads that are applied by the reinforced soil abutment and bridge superstructure, as well as any live loads that are applied by traffic on the bridge or abutment. The RSF is composed of high-quality granular fill material that is compacted and encapsulated within a geotextile fabric. Current GRS-IBS interim implementation design guidelines recommend the use of design methodologies for bearing capacity that are based around rigid foundation behavior, which yield a trapezoidal applied pressure distribution that is converted to a uniform applied pressure that acts over a reduced footing width for purposes of analysis. Recommended methods for determining the applied pressure distribution beneath the RSF for settlement analyses follow conventional methodologies for assessing the settlement of spread footings, which typically assume uniformly applied pressures beneath the base of the foundation that are distributed to the underlying soil layers in a fashion that can reasonably be modeled with an elastic-theory approach. Field data collected from an instrumented GRS-IBS that was constructed over a fine-grained soil foundation indicates that the RSF actually behaves in a fairly flexible way under load, yielding an applied pressure distribution that is not uniform or trapezoidal, and which is significantly different than what conventional GRS-IBS design methodologies assume. This paper consequently presents an empirical approach to determining the applied pressure distribution beneath the RSF in GRS-IBS construction. This empirical approach is a useful first step for researchers, as it draws important attention to this issue, and provides a framework for collecting meaningful field data on future projects which accurately capture real GRS-IBS foundation behavior.     

整体桥台桥梁应用及有限元分析

介绍了整体桥台桥梁的特点、存在的问题和有限元分析方法,并对一座单跨整体桥梁进行了三维有限元分析,给出了在桥梁整体升温和桥面板局部升温两种荷载模式下整体桥台桥梁的荷载效应。     

高填方双管涵洞减荷试验研究

为解决高填方涵洞受力过大的问题,在一双管涵洞上铺设不同密度、不同厚度的单层或双层可发性聚苯乙烯板(EPS板)进行减荷试验,并与未减荷段进行对比,结果表明:涵顶铺设EPS板可以大大减小涵洞受力,涵顶竖向土压力仅为未减荷段的1/3、土柱压力的1/2;同时,EPS板铺设越厚,减荷效果越好,但其效果随板厚的增大而递减,双层叠加...