新型半整体式桥台无缝桥梁的工作原理和设计方法研究

Semi-integral jointless bridge has wider application and more prosperity than integral counterpart in both new construction and old renovation, but for its weakness in seismic resistance and integrity. Therefore, it is not suitable for being constructed in strong seismic zones. A brand-new type of semi-integral jointless bridge is proposed here, which is integrated with road by predrilled concrete micro-pile system. The research will be focused on (1) the accommodation mechanism, transfer path and distribution of the deformation (thermal, shrinkage and creep) among the bridge components in service limit state; (2) the structural dynamic characteristics,seismic responses and aseismic mechanism under various earthquake intensities; (3) the horizontal restoring force hysteresis,horizontal movement accommodation and earthquake energy dissipation mechanism of predrilled concrete micro-pile system. Both experimental and theoretical investigation will be carried out on the aforementioned research items. Furthermore, a test-calibrated FEM will be adopted to carry out the main-parameters sensitivity analysis,such as the number of span, structural type, the properties of seismic excitation, soil type and comprehensive rigidity of micro-piles. Eventually, a simplified analysis and calculation model are expected to be established. The research results will provide a new type of bridge for the massive short-medium span of bridges in the seismic regions and also promote the technical innovation and advancement in the development of earthquake-resistant bridges.

桥梁无缝化是现代桥梁的一个发展方向。半整体式桥台无缝桥梁具有比整体式桥台无缝桥梁更广阔的应用范围和前景, 既可用于新桥的建设，又可用于旧桥的改造。但现行半整体式桥台桥梁的抗震和整体性能较差。为此，申请人提出通过在台后填土中设置扩孔微型桩以提高半整体式桥台桥梁抗震性能的概念。本研究将开展应用该概念的详细的试设计，然后以试设计为原型，以混凝土扩孔微型桩的水平恢复力滞回特性、水平位移吸纳和地震能量的耗散机理为重点，开展系统的试验和理论分析。研究主要内容包括(1)在正常使用极限状态下温度等变形的吸纳机理、传递方式和在各构件间的分配关系；(2)在不同烈度地震动作用下结构的动力特性、地震响应及抗震机制；(3)采用室外静力和室内动力模型试验的结果校准有限元分析模型，对主要设计参数进行敏度分析，并建立简化结构分析模型。研究成果可为地震区中小跨径桥梁的建设和改造提供新桥型，推动无缝桥梁设计理论的创新和完善。

半整体式无伸缩缝桥梁具有广阔的应用范围和前景，构造简单，适用于新桥建设以及旧桥的无缝化和整体化改造加固。针对其相对较弱抗震性能和整体性，本项目提出了一种新型带微型桩耗能体系的抗震型半整体式无伸缩缝桥梁，并对它进行了如下内容的试验研究：（1）进行了侧向荷载作用下新型半整体式桥台桥梁台后扩孔微型桩在不同扩孔参数下的室内足尺试验研究，研究了扩孔微型桩的桩顶位移-荷载曲线、桩身内力、桩身位移及桩侧土抗力等变化发展规律，分析了扩孔与否、扩孔内填料密实度、扩孔深度及扩孔孔径对侧向受荷性能的影响。主要结论是“m”法可用于小位移情况下的微型桩侧向受荷计算，但对于p-y曲线法，实测极限位移明显大于API法给定的极限位移。（2）进行了微型桩—土动力相互作用的振动台试验研究，建立了桩土动力p-y曲线，并分析了输入波频率、桩顶质量和加速度峰值等因素对桩土动力p-y曲线的影响。随着桩顶质量或加速度峰值的增加，p-y曲线的滞回环呈逐渐张开的趋向，其耗能效应增加。（3）最后进行了带微型桩的两跨半整体无缝桥梁的振动台试验研究，测出了结构的动力特性（固有频率、振型、周期等），观察到了结构的最终破坏模式，验证并修正了有限元模型精度，对比分析了无缝桥的不同简化计算模型，建立了适合于带微型桩新型无缝桥梁的简化计算分析模型。研究成果可为我国（地震区）大量建造和改造无缝中小跨径桥梁打下理论基础和技术依据，推动抗震型无伸缩缝桥梁的技术创新和进步。