考虑施工效应时饱和土-薄壁管桩纵向耦合振动机理研究

While the pipe piles more widely applied in various fields of engineering construction,the dynamic interaction characteristics of pipe pile-saturated soil considering construction effect are not clear.Therefore, the vibration mechanism of pipe pile in the saturated soil considering construction effect become the key problem which need to be studied urgently. The vertical vibration mechanisms of uniform cross-section and variable cross-section impedance pipe pile in saturated soil considering construction effect will be studied. Based on the theory of porous medium, saturated soil-pipe pile dynamic model and the saturated soil-variable cross-section impedance pipe pile dynamic model in which construction effect is considered are established. The coupling wave equations will be solved by appropriate mathematical and mechanical methods. After that, the analytical solutions in frequency domain and semi-analytical solution in time domain on the top of pipe pile will be obtained. Then, a comprehensive analysis will be carried on about the influences of construction effect and pipe pile defects. The aim of these study is to reveal the pipe pile vibration mechanism in the saturated soil. Finally, the model test and field test of pipe pile will be carried on. From contrasting the testing datas with the theoretical results, the correctness of the theoretical model will be proved. Furthermore, the research results can provide more complete theoretical guidance for the pipe piles design and dynamic testing.

目前管桩在工程建设各个领域应用越来越广，而对于考虑施工效应时管桩与饱和土的动力相互作用特性尚不明确，因此，考虑施工效应时饱和地基土中管桩的振动机理成为了迫切需要研究的关键问题。本项目研究考虑施工效应时饱和土与均匀截面及变截面阻抗管桩的纵向振动机理。基于多孔介质理论，建立能考虑施工效应的饱和土-管桩动力模型以及饱和土-变截面阻抗管桩动力模型，并采用合适的数学、力学方法求解动力模型的耦合波动方程，获得桩顶频域响应解析解及时域响应半解析解，并全面分析施工效应和桩身质量缺陷对管桩的动力特性的影响，揭示饱和土中管桩的振动机理。展开模型桩和工程桩的现场试验，将实测数据与理论结果进行对比，验证理论模型的正确性，进一步完善管桩振动理论，为管桩的动力设计及动态检测提供更为完善理论指导。

薄壁管桩广泛应用于东南沿海区域，其与饱和土的耦合振动特性研究尚有欠缺，特别是对于考虑施工效应时管桩与饱和土的动力相互作用机理尚不明确，薄壁管桩的动力理论研究还不完善，因此，急需进行考虑施工影响时饱和土-管桩耦合振动机理研究。本项目主要研究了挤密、松弛等施工效应影响下饱和土与均匀截面及变截面阻抗管桩的纵向振动机理，研究了土塞作用对管桩动力响应的影响，并进行了室内模型试验以及数值模型计算。针对施工效应研究，获得了更为合理的均匀薄壁管桩、变截面薄壁管桩与饱和土耦合振动模型，对所得模型进行相应解耦求解，得到了薄壁管桩桩顶频域响应解析解及时域响应半解析解，并全面分析施工效应和桩身质量缺陷对管桩的动力特性的影响，研究表明挤密、松弛效应和土塞作用等施工效应明显影响了饱和土-管桩耦合振动特性，揭示了施工影响下饱和土中管桩的振动机理。研究工作优化了饱和土-管桩振动模型，提升了模型计算的精确度，给出了更加准确的管桩质量无损检测的评判依据。依据各种工况设计了室内模型试验和数值计算模型，充分验证了考虑施工影响下所建立的饱和土-管桩模型的可靠性，为计算模型的工程应用提供保障。项目研究的成果进一步发展和完善了管桩振动理论，能为管桩的动力设计及动态检测等工程应用提供更为完善理论指导。