Advancing the Capabilities of Adaptive Management Techniques in Geotechnics

提高岩土工程中自适应管理技术的能力

• 批准号: 0928184
• 负责人: Richard Finno
• 金额: $ 45.08万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0928184&HistoricalAwards=false
• 关键词: Advancing; Capabilities; Adaptive; Management; Techniques

Adaptive management techniques provide a means to incorporate advances in sensor development, information technology, and numerical analyses to a variety of problems in geotechnical engineering. If one wants to predict and subsequently evaluate the overall performance of a design, the ?observational method? espoused by Peck is a well-known framework wherein construction and design procedures and details are adjusted based upon observations and measurements made as construction proceeds. Adaptive management techniques allow one to automate the observational approach so that quantitative information can be distributed to interested shareholders in a timely enough fashion to be of use in a number of applications. This methodology has particular application when extending civil infrastructure into the subsurface environment. The increase in population density, as well as new imperatives for infrastructure investment, homeland security, energy conservation and sustainable design, will require major advances in our ability to create underground space more efficiently and safely. Many factors affect the ground movements caused by excavations, including stratigraphy, soil properties, support system details, construction activities, contractual arrangements and workmanship. While numerical simulations have become more common when analyzing ground response to excavations as part of the design process, finite element predictions contain uncertainties related to soil properties, support system details, and construction procedures. These factors are explicitly considered when applying adaptive management methods to the problem, although the methodology has its limitations as subsequently discussed. Stricter limits on allowable ground movements associated with deep excavations are being imposed in many locales by either regulatory agencies or by recognition of adverse effects of excessive ground movements. Excavations in some urban areas are being subjected to movement limitations that are much smaller than even just 5 years ago. For example, excavation-induced ground movements in the Seattle area are limited to 1 inch for cuts at deep as 70 ft. Requirements for excavations in Chicago are now targeted for maximum ground movements of 1-1/2 to 2 inches, down from 4 inches just over a decade ago. These issues are compounded in Chicago by the fact that excavations now are being made to depths of 75 ft, much deeper than the typical depth of 40 ft. Many excavations in the Boston area are limited to 1 inch of ground movement. Given that the subsurface conditions at Boston and Chicago consist of relatively soft clays, these requirements present a challenge in excavation support design and construction. Consequently, the state-of-the-art of predicting ground deformations has reached a point where major advances in practice are required to make accurate design assessments when movements are limited to such small amounts. These advances also are needed to make the adaptive management approach applicable to these types of problems.The purpose of this research is to extend the adaptive management approach so that it applies to a range of problems where ground deformations must be limited to prevent damage to adjacent buildings and other infrastructure. In particular it is proposed to quantify the relative effects of small strain non-linearity of soils, non-linear stiffness of walls and shrinkage of floor slabs used in top-down construction on the deformations associated with excavations. This research will include laboratory experiments on block samples cut from excavations in Chicago and Boston to characterize the constitutive behavior of the soils with emphasis on the small strain responses, detailed field experiments at deep excavations where ground deformation and structural responses of the support system are measured and related to the construction activities at the site, and finite element simulations and after-the-fact adaptive management evaluations using inverse analysis based on observed field observations.

自适应管理技术提供了一种手段，将传感器的发展，信息技术和数值分析的各种问题，在岩土工程。 如果想要预测并随后评估设计的整体性能，那么？观察法？Peck所支持的是一种众所周知的框架，其中，基于在施工过程中进行的观察和测量来调整施工和设计程序和细节。 自适应管理技术允许一个自动化的观察方法，使定量信息可以分发给感兴趣的股东在一个足够及时的方式在一些应用程序中使用。 这种方法在将民用基础设施扩展到地下环境时具有特别的应用。 人口密度的增加，以及对基础设施投资、国土安全、节能和可持续设计的新要求，将要求我们更有效、更安全地创造地下空间的能力取得重大进展。 影响开挖引起的地面移动的因素很多，包括地层、土壤特性、支撑系统细节、施工活动、合同安排和工艺。虽然数值模拟已成为更常见的分析地面响应开挖作为设计过程的一部分，有限元预测包含相关的土壤特性，支撑系统的细节，和施工程序的不确定性。 这些因素被明确考虑时，应用自适应管理方法的问题，虽然该方法有其局限性，随后讨论。在许多地区，由于管理机构或认识到过度地面移动的不利影响，对与深开挖相关的允许地面移动施加了更严格的限制。 一些城市地区的居民受到的行动限制甚至比5年前小得多。 例如，在西雅图地区，挖掘引起的地面移动对于70英尺深的切割被限制在1英寸。 芝加哥的挖掘要求现在的目标是最大地面移动1-1/2到2英寸，而十多年前只有4英寸。 这些问题在芝加哥由于挖掘现在正在进行到75英尺的深度，比典型的40英尺深得多的事实而复杂化。 波士顿地区的许多挖掘都限制在1英寸的地面移动。 鉴于波士顿和芝加哥的地下条件由相对较软的粘土组成，这些要求对开挖支护设计和施工提出了挑战。 因此，预测地面变形的最新技术已经达到了这样一个点，即在实践中需要取得重大进展，以便在运动限制在如此小的量时进行准确的设计评估。 这些进步也需要使适应性管理方法适用于这些类型的problems.The本研究的目的是扩展自适应管理方法，使其适用于一系列的问题，地面变形必须加以限制，以防止损坏相邻的建筑物和其他基础设施。 特别是，它建议量化的相对影响，小应变非线性的土壤，非线性刚度的墙壁和收缩的楼板自上而下的施工中使用的变形与开挖。 这项研究将包括对从芝加哥和波士顿的开挖中切下的块体样品进行实验室实验，以表征土壤的本构行为，重点是小应变响应，在深开挖中进行详细的现场实验，测量地面变形和支撑系统的结构响应，并与现场施工活动相关，以及有限元模拟和使用基于观测到的现场观测的逆分析的事后自适应管理评估。