Collaborative Research: Nano-Engineered Superwood for Resilient Foundation Systems

木桩是一种可再生的低成本基础体系。随着钢桩和混凝土桩的发展，木桩的使用逐渐减少，因为木桩的刚度和强度较低，限制了其在轻荷载结构中的应用。本项目旨在为重载弹性民用基础设施开发高刚度、高强度、耐用、高性价比的超级木桩基础系统。最近对基于木材的纳米材料的研究导致了一种被称为超级木材的高性能结构材料，这种材料在民用、汽车、航空航天和制造工程领域的先进应用是理想的。本研究将通过岩土工程和木材复合材料工程研究人员之间的合作，使用实验和建模技术以及生命周期分析来设计和验证超级木桩基础系统。研究团队将通过路易斯安那州立大学（LSU）现有的外展项目，让未被充分代表的少数民族中学生和高中生参与基础和木材复合材料工程的研究。该项目还将有助于路易斯安那州立大学本科生和研究生的培训和教育。超级木是由天然木材部分去木质素，然后通过热压致密生产的致密木材材料。超级木材的生产具有潜在的可持续性和成本效益，因为它避免了与波特兰水泥和钢铁相关的能源密集型制造过程。超级木材的强度和弹性模量不仅优于天然木材，而且可以超过混凝土。超级木材还具有优异的耐久性，可以抵抗湿气引起的腐烂和白蚁等昆虫，强度降低最小。超级木材的显著特性有望使超级木材桩能够(1)减轻当前木材桩的缺点（例如，结构容量低，在硬驱动过程中容易损坏，容易腐烂）；(2)在使用和强度极限状态下超过木材和混凝土桩的性能。本研究的目标是：(1)根据超级木桩的力学性能和抗腐、抗白蚁等耐久性性能，优化超级木桩的生产工艺条件；(2)通过室内试验研究超级木桩的土桩相互作用行为；(3)建立数值模型，预测超级木桩在不同土壤和荷载条件下的响应。(4)通过全寿命周期分析，评估超级木桩的成本和环境影响。这项研究将促进超级木材在岩土工程中的进一步发展，包括地基改善、挡土墙和开挖结构的支撑。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Timber piles are a renewable and low-cost foundation system. With the development of steel and concrete piles, the use of timber piles has steadily declined as timber piles have low stiffness and strength, limiting their applications to lightly loaded structures. This project aims to develop a high stiffness and strength, durable, and cost-effective superwood pile foundation system for heavily loaded and resilient civil infrastructure. Recent research on wood-based nanomaterials has led to a high-performance structural material known as superwood, which is desirable for advanced applications in the fields of civil, automotive, aerospace, and manufacturing engineering. This research will use experimental and modeling techniques and life-cycle analysis to engineer and verify the superwood pile foundation system through collaboration between geotechnical and wood composite engineering researchers. The research team will engage underrepresented minority middle and high school students in research of foundation and wood composite engineering via existing Louisiana State University (LSU) outreach programs. The project will also contribute to the training and education of undergraduate and graduate students at LSU.Superwood is a densified wood material produced by partially delignifying natural wood and subsequent densification through hot-pressing. Superwood production is potentially sustainable and cost-effective as it avoids energy-intensive manufacturing processes associated with Portland cement and steel. The strength and elastic modulus of superwood are not only superior to those of natural wood, but could also exceed those of concrete. Superwood also has excellent durability against moisture-induced decay and insects such as termites with minimal strength reduction. The remarkable properties of superwood are expected to enable superwood piles to (1) mitigate the disadvantages of current timber piles (e.g., low structural capacity, vulnerability to damage during hard-driving, and susceptibility to decay) and (2) to exceed the performance of timber and concrete piles for both service and strength limit states. The objectives of this research are to (1) optimize processing conditions for producing superwood piles in relation to their mechanical properties and durability performance including decay and termite resistances, (2) investigate the soil-pile interaction behavior of superwood piles through laboratory experiments, (3) develop numerical models to predict the responses of superwood piles under different soil and loading conditions, and (4) assess the cost and environmental impacts of superwood piles by performing life-cycle analysis. This research will promote further development of superwood in geotechnical engineering, including ground improvements, retaining walls, and support of excavation structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.