RUI: Pervious Concrete Piles: An Innovative Ground Improvement Alternative

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。渗透性颗粒桩（即压砂桩、石柱和夯集料墩）通常用于在受静力和地震载荷的软或松散土壤上建造的结构和公路设施。透水颗粒桩虽然增加了固结的时间速率，降低了液化潜力，提高了承载力和稳定性，减少了贫瘠土壤的沉降，但这些桩的刚度和强度都很低，这取决于周围土壤的性质。因此，颗粒桩在非常软的粘土和粉砂，以及有机和泥炭土中使用有限。本研究的重点是开发一种新的地面改善替代方案，使用透水混凝土桩来提供高渗透性以及与周围土壤特性无关的高刚度和强度。与颗粒桩的性能相比，透水混凝土材料的渗透性相当，强度提高了十倍以上，模量提高了两个数量级。透水混凝土具有较高的弹性模量和强度，改善了桩的荷载传递和承载能力，同时又不影响高渗透性的好处。使用透水混凝土材料最终会降低所需的面积替换率，从而大大减少施工时间和成本。透水混凝土桩具有强度和刚度特性，不依赖于周围土壤提供的约束，将为非常软的粘土和淤泥以及有机和泥炭土提供有效的地基改善方法。此外，可在透水混凝土桩上加装纵向防腐钢筋，提高透水混凝土桩在地震荷载作用下的延性和性能。研究目标集中于开发用于地基改善应用的透水混凝土混合物，并通过实验表征几种施工程序对土和桩特性以及土-桩相互作用的影响。使用仪器和先进传感器的小规模实验室实验旨在了解安装程序对单个透水混凝土桩和透水混凝土桩组在垂直、隆起、横向和路堤荷载条件下的行为的影响。分析工作的重点是开发计算模型，通过三个阶段准确预测透水混凝土桩系统的行为：桩安装、固结和在役荷载。分析模型将使用实验室材料和桩荷载测试的结果进行校准，并将开发供研究人员使用的复杂分析方法和向执业工程师推荐的简化分析工具。拉斐特学院的土壤-结构相互作用设施，最近得到了国家科学基金会的资助？主要研究仪器计划，将用于进行实验和分析研究。这项研究将大大受益于地质基金会公司在设计和实施实验计划方面的合作。该研究项目团队由来自拉斐特学院的教师和学生组成，这是一个本科非博士学位。资助机构和geoier基金会公司的工程师。该项目每年将资助两名本科生。另外两名学生将通过拉斐特学院获得资助？EXCEL学者计划，该计划支持优秀学生和教师之间的合作研究。研究小组还将与宾夕法尼亚STEM倡议和来自宾夕法尼亚州伊斯顿地区学区的丰富/天赋支持专家和教师合作，开展几个外展项目。通过这些活动形成的伙伴关系支持宾夕法尼亚？该计划旨在大幅增加P-20学生（尤其是女性、少数族裔和代表性不足的学生）在科学、技术、工程和数学领域的人数。项目团队将与PA STEM东北区域网络合作，与几个地区K-12学校（总计约4000名学生）的学生和教师一起工作。具体来说，参加年度研讨会和？项目领导？让学生参与高中工程预科课程和基督教女青年会？年代?科技Gyrl ?通过发展计算机技能来增强中学女生能力的项目将使学生和他们的老师接触到在贫瘠土壤上设计支撑结构的挑战。通过专业委员会的工作和服务，会议发言，期刊论文，以及参加CMMI年会；pi和学生将在国内和国际上传播这项研究工作产生的数据、方法和工具。

This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5).Permeable granular piles (i.e., sand compaction piles, stone columns and rammed aggregate piers) are commonly used to support structures and highway facilities constructed on soft or loose soils subjected to static and seismic loading. Although the use of permeable granular piles increases the time rate of consolidation, reduces liquefaction potential, improves bearing capacity and stability, and reduces settlement of poor soils, these piles have a low stiffness and strength that depend on the properties of surrounding soil. Therefore, granular piles have limited use in very soft clays and silts, and in organic and peat soils. This research focuses on developing a new ground improvement alternative using pervious concrete piles to provide high permeability coupled with high stiffness and strength that are independent of surrounding soil properties.When compared to the properties of granular piles, pervious concrete materials provide comparable permeability, more than ten times the strength, and an increase of two orders of magnitude in modulus. The higher elastic modulus and strength of pervious concrete improves the load transfer and load-carrying capacity of the piles without compromising the benefits of high permeability. Using pervious concrete material will ultimately result in reducing the required area replacement ratio, which will significantly reduce construction time and cost. Pervious concrete piles, which have strength and stiffness properties that do not depend on confinement provided by surrounding soil, will provide an effective ground improvement method for very soft clays and silts, and in organic and peat soils. In addition, pervious concrete piles can be reinforced with longitudinal corrosion-resistant steel rebars to improve their ductility and performance when subjected to seismic loading.The research objectives focus on developing pervious concrete mixtures for ground improvement applications and on experimentally characterizing the effects of several construction procedures on soil and pile properties and on soil-pile interaction. Small-scale laboratory experiments using instrumentation and advanced sensors are designed to understand the effects of installation procedures on the behavior of single pervious concrete piles and groups of pervious concrete piles subjected to vertical, uplift, lateral,and embankment loading conditions. The analytical work focuses on developing computational models that accurately predict the behavior of pervious concrete pile systems through three stages: pile installation, consolidation, and in-service loading. The analytical models will be calibrated using the results of the laboratory material and pile load tests and both sophisticated analytical methodologies for use by researchers and simplified analytical tools recommended for practicing engineers will be developed. The Soil-Structure Interaction Facility at Lafayette College, which was recently funded by the National Science Foundation?s Major Research Instrumentation Program, will be used to conduct the experimental and analytical studies. The research will benefit significantly from the collaboration of the Geopier Foundation Company in the design and conduction of the experimental program. The research project team consists of faculty and students from Lafayette College, which is an undergraduate non-Ph.D. granting institution, and engineers from Geopier Foundation Company. Two undergraduate students will be funded by the project each year. Two additional students will be funded through Lafayette College?s EXCEL Scholars Program, which supports collaborative research between high-performing students and faculty. The research team will also collaborate with the Pennsylvania STEM Initiative and an enrichment/gifted support specialist and teacher from the Easton Area School District, PA, in several outreach programs. The partnerships formed through these activities support the Pennsylvania?s STEM Initiative to dramatically increasing the number of P-20 students (especially females, minorities and the underrepresented) in Science, Technology, Engineering and Mathematics careers. The project team, in collaboration with the Northeast Regional Network of PA STEM, will work with students and teachers in several area K-12 schools (total ~4000 students). Specifically, participating in yearly workshops and ?Project Lead the Way? that engage students in high school pre-engineering programs and the YWCA?s ?Tech Gyrl? program that empowers middle school girls by developing computing skills will expose students and their teachers to the challenges associated with designing structures supported on poor soils. Through professional committee work and service, conference presentations, journal papers, and participating in the CMMI annual meeting; the PIs and students will disseminate the data, methods, and tools produced by this research effort nationally and internationally.