无伸缩缝桥梁研究综述

综述了无伸缩缝桥梁(简称“无缝桥”)技术发展，介绍了无缝桥优点、应用和研究热点，分析了无缝桥纵桥向受力特点、桩-土相互作用、台后土压力与抗震性能，指出了新技术研发与应用的现状与发展方向。分析结果表明:无缝桥技术受到许多国家的重视，已开展了大量的实桥监测和其他研究；在纵桥向受力方面，温度变形是其主因，现有规范中所给出的平均温差与实桥监测结果相差较大，应研究精度更高的计算方法；桩-土相互作用是整体桥受力的特点与研究的难点，在计算土抗力时，m法应限于小位移的无缝桥，位移较大时宜采用p-y曲线法；桥台桩基受力复杂，H型钢桩存在屈服、疲劳、屈曲的破坏可能，混凝土桩则易出现开裂病害；无缝桥温升时台后土压力增大，是研究的热点与难点，它随水平变形量和往复变形次数增大而增大的机理、量值和分布未达成共识，有待今后深入、系统的研究；纵桥向受力分析应建立全桥有限元模型，考虑结构-土相互作用和节点非线性性能；钢主梁受压稳定性和混凝土主梁抗裂性能是研究与设计的关键；引板是无缝桥的病害易发构件，面板式引板应减小板底摩阻力，避免开裂和末端沉降，而斜埋入式引板应控制其末端之上接线路面的隆起和下陷；许多无缝桥新技术已被提出并得到应用，今后还需深入研究，如:新材料与新构造在无缝桥各组成部分、台背、桩基与引板中的应用等；无缝桥具有较强的结构强健性、抗倒塌和防落梁能力，抗震研究已取得可喜的进展，但许多国家尚未形成相关的设计规定，应继续研究，为将来的应用和规范制订提供科学依据。 

Review on research of jointless bridges

The technological development of jointless bridges was reviewed, the advatages, application and research hotspots were introduced, the longitudinal stress characteristics, pile-soil interaction, earth pressure of backfill on the autment and seismic performance were analyzed, and the present situation and development direction of the new technology research and application were pointed out. Analysis results show that the technologies of jointless bridges have been attached to importance in many countries, and a large number of field monitoring projects and other researches have been carried out. The temperature-induced deformation is the main cause of longitudinal stress of jointless bridge, and the average temperature difference predicted by the codes is quite different from the data obtained from field monitoring. Therefore, a preciser calculation method should be developed. Pile-soil interaction is the dominant characteristic of integral bridge and is the emphasis and difficulty of the research. In calculating the soil resistance, the m method should be limited to jointless bridges with small movements, while the p-y curve method should be employed when the movements are larger. The piles of the integral abutments are stressed complexly, H-shaped steel piles may be subjected to yielding, fatigue, and buckling, while RC piles are prone to be damaged by cracking. The high earth pressure behind the abutment induced by temperature rise is a hot spot and difficulty in the research. The mechanism, magnitude, and distribution of the earth pressure increasing with the horizontal movement and reciprocating number have not reached a consensus, and need to be further studied systematically. In analyzing the longitudinal behaviour of jointless bridge, the finite element model should involve the whole structure of the bridge, and considering the soil-structure interaction and the nonlinear performance of the joint. The stability of steel girders under compression and the crack-resistance of concrete girders under tension are the key points in research and design. The approach slab is an important and damage-prone component of jointless bridges. For the grade flat approach slabs, the frictional resistance at the bottom should be reduced, and the cracking and end settlement should be avoided. While for the buried inclined approach slabs, the swell and settlement of approach pavement above their ends should be controlled. Many new technologies for jointless bridges have been proposed, applied, and should be further studied, including the application of new materials and new details in various components, abutments, pile foundations, and approach slabs of jointless bridges. Jointless bridges have higher structural robustness and capability to prevent collapse and unseating of the superstructures. The research on the seismic resistance of jointless bridges has made gratified progress, but the relevant design regulations have not been formed in many countries. It is necessary to conduct comprehensive research to provide a scientific basis for engineering application and the formulation of the specifications in the future.