Reliability-based geotechnical design

我们发现结构的地面是所有工程材料中最可变和最不确定的之一，因此非常适合概率处理。由于土力工程师往往须处理地盘现有的土地，因此，任何土力工程设计的一个关键问题便变成“我们应如何设计我们的土力系统，以达致可接受的安全水平？“这个问题涉及到其他一些重要的问题，例如：我们如何减少对地面工程特性的不确定性？我们对自己的预测和设计模型有多大信心？我们应该如何调整我们的设计，以考虑不同的失败后果？而且，最重要的是，设计规范应该如何实施，以解决所有这些问题，并仍然达到社会可接受的安全水平？ 这项研究建议着眼于具体的可靠性为基础的岩土工程设计规范的发展。现有的岩土工程设计规范几乎完全是经验性的-基于过去经验的校准，特别是传统的工作应力设计方法。拟议的研究将集中在确定设计阻力和后果因素，以实现可接受的安全岩土系统的不同程度的现场理解和故障后果。结果将直接输入下一版的加拿大公路桥梁设计规范。 有几个显著的优势，提供编码的阻力系数，随着现场的理解沿着后果因素，随着故障的严重程度而变化。首先，它们为岩土工程师提供了证据，证明更好的现场理解可以带来设计上的经济效益。另一方面，它们允许适当分配有限的基础设施预算。最后，他们为所有岩土工程师提供指导，说明现场理解和故障后果应如何影响最终设计。以可靠性为基础的岩土工程设计规范的制定将是一个重大的进步，并将在未来几年内大大节省基础成本。

The ground on which we found our structures is one of the most variable and uncertain of all engineering materials and is therefore highly amenable to a probabilistic treatment. Since geotechnical engineers must often make do with the existing ground at a site, a key question in any geotechnical design then becomes "How should we design our geotechnical system so as to achieve an acceptable safety level?" The question involves a number of other important issues such as: How can we reduce our uncertainty about the ground's engineering properties? How confident are we in our prediction and design models? How should we adjust our designs to account for differing failure consequences? And, most importantly, how should design codes be implemented in order to address all of these issues and still arrive at societally acceptable levels of safety? This research proposal looks specifically at the development of a reliability-based geotechnical design code. Existing geotechnical design codes are almost entirely empirical -- based on calibration with past experience, particularly with traditional working stress design methodologies. The proposed research will concentrate on determining design resistance and consequence factors necessary to achieve acceptable safety in geotechnical systems for various degrees of site understanding and failure consequence. The results will feed directly into the next edition of the Canadian Highway Bridge Design Code. There are several significant advantages to providing codified resistance factors that vary with site understanding along with consequence factors that vary with failure severity. For one, they provide geotechnical engineers with evidence that better site understanding leads to economies in design. For another, they allow limited infrastructure budgets to be properly allocated. Finally, they give guidance to all geotechnical engineers on how both site understanding and failure consequence should affect the final design. The development of a reliability-based geotechnical design code will represent a substantial step forward and will lead to significant savings in foundation costs in the years to come.