Field research study of three-sided precast structures

涵洞被用来通过堤坝输送水、公用设施或行人，它们被认为是所有社会城市基础设施的战略组成部分。作为箱形涵洞的替代方案，三面涵洞越来越受欢迎，因为它们的优点包括：安装迅速；施工容易；与箱形涵洞相比，成本较低；对水环境的影响最小。它们目前是按照钢筋混凝土的惯例设计的，假定土压力分布为箱形涵洞，这导致设计过于保守。因此，本研究的目的是：了解三边涵洞的受力性能及其影响因素，确定其实际受力条件，并在足尺实测的基础上为其设计制定专门的准则。预制混凝土三面结构与周围土体的相互作用受多种因素的影响，如涵洞形状、结构刚度、埋深、基础刚度等。这些因素将影响施加在结构构件上的土荷载(垂直和横向)以及推力、剪力和弯矩，从而影响其设计。预计这项研究将建立一种稳健而简化的三面涵洞设计方法，并检验当前三面涵洞实践设计方法标准的适用性和局限性。这项研究的结果将导致可靠且具有成本效益的三面涵洞设计。美国交通运输中使用的预制混凝土产品价值20亿美元(弗里多尼亚集团，2018)，加拿大市场约为2亿美元。

Culverts are used to convey water, utilities, or pedestrians through embankments and they areconsidered as a strategic part of the urban infrastructure for all societies. Three-sided culverts are gaining popularity as an alternative to box culverts owing to their advantages, including: quick installation; ease of construction; reduced cost compared to box culverts; and minimal impact on the aquatic environment. They are currently designed in accordance with common practice of reinforced concrete with assumed earth pressure distribution as box culverts, which leads to an overly conservative design. Therefore, this research aims to: understand the behavior of three sided culverts and the factors that affect their behavior, establish their actual loading conditions and develop special guidelines for their design based on full scale field measurements. Many factors are expected to influence the interaction of precast concrete three-sided structures with the surrounding soil, such as: culvert shape, structure stiffness, embedment depth, and foundation rigidity. These factors will affect the applied earth loads (vertical and lateral) as well as thrusts, shear forces and bending moments applied to the structural elements and consequently their design. It is expected the research will establish a robust, yet simplified design method for three sided culverts and examine the applicability and limitations of the current standard of practice design methods of three sided culverts.The findings from this research will result in reliable and cost effective design of three-sided culverts.The precast concrete products used in transportation in the USA amount to $2.0B (Freedonia Group, 2018) with the Canadian market is approximately $200M.