基于声子晶体的周期结构埋地管道振动带隙特性与减振方法研究

Buried pipeline is the important underground lifeline engineering. Its safe operation is of great significance. Vibrations caused by low-frequency excitations, such as earthquake, construction, transportation, etc. are the important reasons to lead to the damage of buried pipeline. Therefore, in order to ensure its safe operation, vibrations under low-frequency excitations must be reduced. However, most of the existing vibration reduction methods of buried pipeline just effectively apply to limited low-frequency ranges, and rely too much on external components as well; therefore it is hard to meet the actual vibration reduction requirements, by using these methods. So we will try to establish a new vibration reduction method for buried pipeline, which could effectively aim at the working frequency ranges of various low-frequency excitations. Moreover, the method could be independent of external components. To achieve this purpose, we will introduce the concept of phononic crystals to straight and curved buried pipelines, and obtain band gaps (BGs) characteristics which could reduce vibrations, from periodic construction, by using common pipeline materials. Based on the soil-pipeline-fluid interaction theory, Bloch theorem, finite element method and experimental system we designed, we will study the mechanisms, characteristics and widening methods of the flexural, axial and coupling vibration BGs. On this basis, finally, the feasible vibration reduction method for buried pipeline under various low-frequency excitations will be established by using vibration BGs. The research could give innovative vibration reduction method for buried pipeline, which is of great significance for assuring the safe operation of buried pipeline under vibration environment.

埋地管道是重要的地下生命线工程，其安全运行意义重大。地震、施工、交通等低频激励所致振动是造成其破坏的重要原因。故要确保其安全运行，必须设法广泛抑制其在各低频激励下发生振动。而现有埋地管道减振方法一般低频减振范围有限且过多依赖外部部件，难以广泛满足实际减振需求。为此，本项目将试图建立一种有效针对各低频激励发生频率范围，且不依赖外部部件的埋地管道减振新方法。为实现该目的，本项目将把声子晶体概念引入埋地管道，通过用常见管材对直型、弯型埋地管道进行周期性构造，使其自身产生抑制振动的带隙特性。基于土体—管道—流体相互作用理论、Bloch理论、有限元法及自行设计的实验系统，研究并阐明其弯曲、轴向及耦合振动带隙机理、特性与拓宽方法。在此基础上，最终建立利用振动带隙广泛抑制埋地管道在各低频激励下发生振动的可行方法。研究成果将丰富并创新埋地管道减振方法，对确保埋地管道在振动环境下安全运行具有重要意义。

埋地管道是重要的地下生命线工程。如何减小振动对埋地管道的影响，是确保其安全运行必须解决的关键问题之一。但现有埋地管道减振方法一般低频减振范围有限且过多依赖外部部件，难以广泛满足实际减振需求。为此，本项目将声子晶体概念引入埋地管道，以周期结构埋地管道为对象，研究其振动带隙特性及利用该特性抑制其在低频激励下发生振动的理论与可行方法。.本项目开展了三方面研究，包括直型周期结构埋地管道的弯曲与轴向振动带隙特性；弯型周期结构埋地管道的耦合振动带隙机理与特性；针对低频激励集中发生频率范围的埋地管道周期构造与带隙设计方法。证实了三个关键科学问题，即在低频激励集中发生的频率范围内，周期结构埋地管道存在振动带隙；在弯型周期结构埋地管道中，存在范围及效果叠加的耦合振动带隙；周期结构埋地管道的带隙可涵盖各低频激励集中发生的频率范围。.本项目重要研究工作及结果包括：（1）建立了直型周期结构埋地管道典型模型与振动带隙计算方法。发现其中存在弯曲振动、纵向振动等四种类型振动；使用弹性模量与密度均较小的材料（如PVC）、增大周期长度、减小管径、增大土体刚度等均有助于获取频率更低、范围更宽、带隙振动阻止效果更好的带隙。（2）建立了弯型周期结构埋地管道典型模型与耦合振动带隙确定方法。发现其中弯曲与纵向振动带隙合并范围内的振动均可被减弱，而弯角基本不影响耦合振动带隙的范围和效果；带隙与通带重叠范围，带隙内的振动衰减减弱，但带隙仍然存在消振效果。（3）建立了通过组合不同形式周期结构埋地管道使振动带隙互补拓宽的方法。在系统研究联合振动带隙特性的基础上，确定了通过参数设计拓宽振动带隙的原则。通过两个案例说明了利用带隙特性实现埋地管道有效消振的效果和可行性。.本项目为利用振动带隙有效抑制埋地管道振动提供了科学依据，为埋地管道消振探索出新的可行方法，对于确保埋地管道在振动环境下安全运行，具有重要意义。