Field research study of three-sided precast structures

涵洞用于通过堤防输送水、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。三面涵洞作为箱形涵洞的替代方案越来越受欢迎，因为它们的优点包括：安装快速；易于建造；与箱形涵洞相比成本降低；对水生环境的影响最小。目前它们的设计是按照钢筋混凝土的一般做法，假设土压力分布为箱涵，这导致了过于保守的设计。因此，本研究旨在：了解三面涵洞的行为和影响其行为的因素，建立其实际加载条件，并在全尺寸现场测量的基础上制定其设计的专门指南。影响预制混凝土三面结构与周围土体相互作用的因素有：涵洞形状、结构刚度、埋置深度和基础刚度。这些因素将影响施加的土荷载（垂直和横向），以及施加在结构元件上的推力、剪力和弯矩，从而影响其设计。期望本研究能够建立一种稳健而简化的三面涵设计方法，并检验现行三面涵设计实践方法标准的适用性和局限性。本研究结果将有助于设计可靠且具成本效益的三面涵洞。美国运输中使用的预制混凝土产品价值20亿美元（Freedonia Group， 2018年），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.