Development of limit state design for rock engineering in fractured rock masses

这项研究将解决岩土工程中重要而及时的问题，即建立用于岩石工程的极限状态设计(LSD)协议。它将通过提供新的工具和技术直接造福于工程师，通过允许更经济和可靠的设计而造福社会，通过发展对裂隙岩体工程性能的更好理解而造福于工程科学。 在土木工程中，LSD原则在提高经济性和可靠性方面带来的许多好处已经被认识到很多年了。在过去的二十年里，这些原理被发展应用于岩土工程中，结果是现在使用极限状态概念对地基和土壤中的斜坡等结构进行了优化设计。然而，对于任何破碎岩石中的工程--无论是公路岩质边坡、运输隧道、地下采矿作业或任何其他目的--LSD的强大应用是不可能的，结果是必须采用次优设计方法。 LSD目前不能应用于岩体的主要原因是与它们包含的裂缝相关的不确定性。这种不确定性包括它们的位置、方向和强度等力学特性，以及它们对岩石中产生的应力和对强度和稳定性的影响等方面的影响。 到目前为止，岩土工程中的LSD假设随机变化--即所谓的任意不确定性--描述了土壤性质的变异性。然而，对于破裂的岩石来说，认知上的不确定性--缺乏信息或知识--是至关重要的。因此，利用应用数学和其他工程领域的持续发展，这项研究将建立一种方法，通过这种方法可以处理裂隙岩体固有的认识不确定性，从而导致从根本上改进设计方法的发展。

This research will tackle the important and timely issue in geotechnical engineering of establishing limit state design (LSD) protocols for use in rock engineering. It will be of direct benefit to engineers by providing new tools and techniques, to society by permitting more economic and reliable designs, and to engineering science through the development of improved understanding of the engineering performance of fractured rock masses. In civil engineering, the many benefits brought by LSD principles in terms of improved economy and reliability have been recognised for many years. Over the last two decades these principles have been developed for application in geotechnical engineering, with the result that structures such as foundations and slopes in soil are now optimally designed using limit state concepts. However, for any engineering in fractured rock -- be it for highway rock slopes, transportation tunnels, underground mining operations or any other purpose -- robust application of LSD is not possible, with the result that sub-optimal design methods have to be employed. The principal reason why LSD cannot currently be applied to rock masses is the uncertainty associated with the fractures they contain. This uncertainty includes their location, orientation and mechanical properties such as strength, as well as the effect they have on aspects such as the stress induced in a rock mass and the affect this has on strength and stability. To date, LSD in geotechnical engineering has assumed that random variation -- so-called aleatoric uncertainty -- describes the variability of soil properties. However, for fractured rocks it is epistemic uncertainty -- a lack of information or knowledge -- that is critical. Thus, and drawing on continuing developments in both applied mathematics and other fields of engineering, this research will establish means by which the epistemic uncertainty inherent in fractured rock masses can be handled, thereby leading to the development of radically improved design methods.