Transforming Robust Design Concept into a Novel Geotechnical Design Tool

在传统的基于安全系数或可靠性的岩土工程设计中，通常首先满足安全要求，然后选择成本最低的设计作为最终设计。然而，如果“噪声因素”（即“难以控制”的因素，如土壤参数）的实际变化大大超过设计阶段假定的变化水平，则最低成本的设计可能会变得不令人满意。如果不能保证设计对噪声因素的“稳健性”，那么成本优化就变得无关紧要了。更合理的方法是实现设计稳健性，从而最终降低成本。为此，将开发一种“坚固的岩土设计”方法，除了成本和安全要求外，还明确考虑坚固性。这个项目将把稳健设计概念转化为一种新颖的、计算机辅助的岩土工程设计工具。稳健设计的目的是尽量减少不确定性对“系统”的影响，而不是真正消除不确定性的来源。本研究的具体目标是：(1)开发一种稳健的岩土设计方法，以实现设计的安全性、稳健性和效率；(2)证明这种新方法在城市地区支撑挖掘中的适用性；(3)向工程专业传播新方法；(4)通过培训岩土工程领域的高素质人才来开发人力资源。鲁棒岩土设计是通过马尔可夫链蒙特卡罗技术在全自动框架中实现的。该项目的智力创新包括开发一种新的岩土设计工具，预计将对岩土工程实践产生广泛的积极影响。除了鲁棒岩土设计的新颖性外，该研究还解决了城市建设中的一个重要需求，即提高支撑开挖的安全性。采用这种新的设计方法，可减少“噪音因素”的影响，从而减少或消除因挖掘失败及/或挖掘对邻近构筑物造成损害而可能对社会及经济造成的不利影响。鲁棒岩土设计方法的开源计算机代码可以为其他研究人员和工程师提供有用的学习和开发援助。如果成功实施，这项研究可以刷新岩土工程解决方案与新开发的鲁棒岩土设计方法。本研究对基坑支护的设计和施工，以及岩土工程设计实践具有积极的影响。改进的设计方法可以消除或减少可能造成不利的社会和经济影响的挖掘失败的机会，从而造福社会。所开发的鲁棒性岩土设计方法可以应用于岩土工程以外的相关领域。通过传播已开发的案例历史数据库、可靠的设计方法、开放源代码的计算机代码、研究成果、将研究和教育结合起来，并特别注意从代表性不足的群体中征聘和培养研究助理，实现了更广泛的影响。

In traditional factor-of-safety-based or reliability-based geotechnical engineering design, safety requirements are first satisfied, and then a design with lowest cost is usually selected as the final design. However, the lowest cost design may become unsatisfactory if the actual variation of "noise factors" (i.e., "hard-to-control" factors such as soil parameters) greatly exceeds the level of variation assumed during the design phase. The cost optimization becomes irrelevant if the "robustness" of the design against noise factors cannot be assured. A more rational approach is to achieve design robustness which can ultimately reduce the cost. To this end, a "Robust Geotechnical Design" methodology will be developed, which considers robustness explicitly, in addition to the cost and safety requirements. This project will then transform the Robust Design concept into a novel, computer-aided geotechnical engineering design tool. Robust design aims to minimize the effect of uncertainty on the "system" without actually eliminating the sources of uncertainty. The specific objectives of this research are to (1) develop a Robust Geotechnical Design methodology to achieve design safety, robustness, and efficiency, (2) demonstrate the applicability of this new methodology in braced excavations in urban areas, (3) disseminate the new methodology to the engineering profession, and (4) develop human resources by training highly qualified personnel for the geotechnical field. Robust Geotechnical Design is implemented in a fully automated framework through the Markov-Chain Monte Carlo technique. The intellectual innovation of the project includes the development of a new geotechnical design tool that is expected to have a broad positive impact on geotechnical practice. In addition to the novelty of Robust Geotechnical Design, the research addresses an important need in urban construction, namely, improving the safety of braced excavations. Adopting this new design methodology can reduce the effects of "noise factors" and thus, reduce or eliminate the possible adverse social and economic impacts caused by excavation failure and/or excavation-induced damages to the adjacent structures. Open-source computer codes for Robust Geotechnical Design methodology can be a useful learning and development aid to other investigators and engineers. If successfully executed, this research can refresh geotechnical engineering solutions with the newly developed Robust Geotechnical Design methodology. This research stands to positively impact the design and construction of braced excavations in particular, and geotechnical engineering design practice in general. Improved design methods can benefit society by eliminating or reducing the chance of excavation failure that may cause an adverse social and economic impact. The developed Robust Geotechnical Design methods can potentially be used in related fields beyond geotechnical engineering. Broader impacts are achieved through dissemination of the developed database of case histories, robust design methodology, open-source computer codes, research findings, integration of research and education with special attention to recruiting and nurturing research assistants from underrepresented groups.