Identifying mechanisms of environmentally driven long-term crack growth in brittle rocks

在靠近开挖表面或地球表面的岩石中形成的裂缝可能会对现有基础设施造成严重破坏，导致作业中断，并在发生意外故障时造成人员伤亡。即使没有造成严重的破坏，形成的裂缝也会导致安全壳设施的流动通道出现问题。通常，经验和数值设计侧重于损害程度和减轻措施，很少关注长期过程。此外，环境因素对裂纹扩展的影响仍然是研究的前沿。该项目的长期目标是改进工程实践，使环境驱动的长期裂缝增长机制、相关危害和适当的缓解策略都包括在设计中。该项目包括开发现场监测方法，设计反映现场条件的实验室测试方案，并利用这些发现开发和验证危害评估和预测数值工具。在短期内，该研究计划的目标是确定最合适的数值软件来模拟长期裂纹扩展的环境影响，了解热循环对不同尺度下裂纹打开和扩展的影响程度，确定应力脆性岩石中的应力腐蚀是否是比其他已确定的机制更主要的裂纹扩展机制，并评估不同数据源从一个地点到另一个地点的可转移性。用于解决上述目标的方法将包括各种现场，实验室和数值模拟方法。对于实地地点，地质测绘、强度估计和样本收集、先进的摄影测量和空间分析结果将增加监测数据，以解决这些信息到新地点的可转移性问题。在实验室中，标准强度和先进的长期可变气候条件下的测试将用于描述岩石和裂纹行为，并为数值模型开发输入。通过计算模型来对现场和实验室行为进行反向分析，并与从普通工程到先进的多物理场和断裂力学软件的不同方法进行比较。这些发现将导致新的测试程序，监测和利用监测数据的新方法，最重要的是将导致开发急需的数值工具来捕获长期裂纹扩展机制。凭借申请人过去在这些领域的经验，以及HQP团队，该项目将在岩石和断裂力学以及近地表过程研究领域取得重大进展。预计将对土木工程界思考和处理长期裂缝增长的环境影响的方式产生重大影响。

Cracks forming in rock near the surface of an excavation or at the Earth's surface can result in critical damage to existing infrastructure, disruption of operations, and loss of life when unexpected failures occur. Even if critical damage is not caused, the cracks formed can result in problematic flow pathways for containment facilities. Typically, empirical and numerical designs focus on the extent of damage and mitigation measures, with little attention to long-term processes. In addition, the influence of environmental drivers on crack growth remains a frontier of research. To improve engineering practice to the point that environmentally driven long-term crack growth mechanisms, the associated hazards and proper mitigation strategies are included in design is the long-term goal of this program. The program includes developing field monitoring methodologies, designing laboratory testing scenarios that reflect the field conditions, and using these findings to develop and validate hazard assessment and predictive numerical tools. In the short-term, the research program will aim to determine the most suitable numerical software to model environmental influence of long-term crack growth, to understand the influence of thermal cycles on the magnitude of crack opening and growth at different scales, to determine if stress corrosion in stressed brittle rock is a dominate crack growth mechanism over other identified mechanisms, and to evaluate the transferability of different data sources from one field location to another. The methods to be used to address the objectives mentioned above will include a variety of field, laboratory, and numerical modelling approaches. For the field sites, geological mapping, strength estimation and sample collection, advanced photogrammetric and spatial analysis of the results will augment the monitoring data to address the transferability of this information to new locations. In the laboratory, standard strength and advanced long-term tests under variable climates will be used to characterize the rock and crack behaviour and develop inputs for numerical models. Models to back analyze both the field and laboratory behavior will be computed and compared with different approaches from common engineering to advanced multi-physics and fracture mechanics software. These findings will lead to new testing procedures, novel methods of monitoring and utilizing monitoring data, and most importantly will lead to the development of much needed numerical tools to capture long-term crack growth mechanisms. With the applicant's past experience in these areas, along with a team of HQP, the program will make major advances in the areas of rock and fracture mechanics, and near surface process research. Major impacts on the way the Civil Engineering community thinks about and deals with environmental influences on long-term crack growth are expected.