Career: Geosynthetic-Reinforced Soil Structures Subject to Strong Earthquake Loading

这一行动是在美国国家科学基金会教师早期职业发展(CALEAR)计划(NSF00-)范围内采取的，以支持一个研究/教育职业项目，该项目使用土工合成材料加筋土结构来抵御强烈地震震动。土工合成材料为许多土木工程结构的加筋土技术提供了一种经济有效的解决方案。它们作为土工合成材料加筋土挡墙(GRS-RW)得到了广泛的应用，尤其是模块砌块GRS-RW因其美观而广受欢迎。但在结构上，土工合成材料的这些用途和其他用途在抵御地震活动方面发挥了更为关键的作用。虽然这种土工合成材料加筋土在常规(静态)荷载下的性能良好，甚至在小地震下也表现良好，但最近的经验表明，需要提高对其在强烈地震震动下的反应的认识和性能。在1999年的台湾地震中，产生了很大的加速度，同时也产生了很大的垂直分量，几个土工合成加筋土体结构倒塌了。显然，现有的分析和设计程序没有考虑到如此严重的动态加载。这一研究和教育计划解决了这一缺陷。该项目建立在先前的实验和数值研究基础上，并与日本的研究人员进行了国际合作。为了更好地了解模型的破坏模式，利用日本最先进的振动台设备，在包括竖向加速度在内的复杂动态载荷条件下对模型进行试验。其结果是改进了对土壤、土工合成加筋及其相互作用的表征。额外的参数研究将导致一个简化的程序，使GRS-RW能够基于永久位移进行设计。除了对设计界的技术价值外，该研究计划还提供了一个有价值的教育工具。讨论了两个具体的教育应用程序。首先，土工合成废料控制和土工地震工程的课程将直接使用这些结果，已经介绍了PI当前研究的基于网络的主页也将使用这些结果。此外，还将开发一个基于网络的软件包(Java Geotech)，并将加入目前活跃的本科生地球科学技术论坛。其次，该项目涉及目前具有吸引力的抗震和环境修复领域的应用，将有助于鼓励高中生，特别是少数民族学生，继续与这些领域相关的学习。这将通过哥伦比亚大学的两个相关项目来实现，以鼓励少数民族对科学和工程的兴趣：双重发现中心和萨尔瓦多教育中心。通过这些中心的工作，关于加固土结构和废物控制系统的教学模块可以通过高中的讲座和实验室演示以及实地考察来介绍，例如到目前正在扩建的肯尼迪国际机场和哥伦比亚的生物圈。

This action is taken within the NSF Faculty Early Career Development (CAREER) Program, NSF 00-89, to support a research/education career project in the use of geosynthetic-reinforced soil structures to resist strong earthquake shaking. Geosynthetics provide a cost-effective solution in reinforced soil technology for many civil engineering structures. They have been applied widely as geosynthetic-reinforced soil retaining walls (GRS-RW), especially modular block GRS-RW that has gained wide popularity because of its pleasing esthetics. But structurally, these and other uses of geosynthetics serve a much more critical purpose in resisting seismic activity. While the performance of such geosynthetic-reinforced soils under routine (static) loads, and even minor earthquakes, has been good, recent experience indicates that improved knowledge and performance is needed regarding their response under strong earthquake shaking. In the 1999 Taiwan earthquake that produced large acceleration together with a large vertical component of that acceleration, several geosynthetic-reinforced soil structures collapsed. Clearly, available analysis and design procedures did not account for such severe dynamic loading. It is this shortcoming that is addressed in this research and education program.The project builds upon prior experimental and numerical research, and international cooperation with researchers in Japan undertaken by the PI. State-of-the-art shaking table facilities in Japan are used to test models under complex dynamic loading conditions, including vertical acceleration, in order to understand better the failure modes. The result is an improved characterization of the soil, the geosynthetic reinforcement, and their interaction. Additional parametric studies will result in a simplified procedure that enables GRS-RW to be designed based on permanent displacement.In addition to the technical value to the design community, this research program also provides a valuable tool for education. Two specific educational applications are addressed. First, the courses on geosynthetic waste containment and geotechnical earthquake engineering will use the results directly, as will the web based home page that already presents the PI's current research. In addition, a web based software package (Java Geotech) will be developed, and will join the currently active Geotech Forum for undergraduates. Second, this project, which involves applications in currently appealing areas of earthquake resistance and environmental remediation, will serve to encourage high school students, and especially minority students, to pursue studies relating to these areas. This will be accomplished through two Columbia University related programs to encourage interest in science and engineering among minorities: the Double Discovery Center and the Salvadori Education Center. Working through these Centers, teaching modules on reinforced soil structures and waste containment systems can be presented through lectures and laboratory demonstrations in high schools and through field trips, such as to JFK International Airport that is currently undergoing expansion, and to Columbia's Biosphere.