Multiscale modeling and analysis of shear response at dam-rock interfaces

魁北克省的《大坝安全法》及其附属法规于2002年4月11日生效，要求大容量大坝的所有者定期评估和监测其在各种荷载作用下的结构行为。在这种背景下，对大坝-岩石相互作用的适当理解对于评估混凝土坝的结构稳定性至关重要。CRD研究方案的主要目的是：(I)开发一个经过实验验证的多尺度数值模型，能够预测大坝-岩石界面的表观粘结强度；(Ii)利用所开发的数值模型进行参数分析，研究不规则坝岩界面的表观粘结强度和膨胀对实际混凝土坝滑动稳定性的影响；(Iii)利用所获得的结果，建立新的本构关系，该本构关系可以在魁北克水电公司目前使用的软件中实现，以根据大坝安全法规的要求进行大坝稳定分析；以及(Iv)如果所获得的结果清楚地表明要考虑坝岩界面处的表观粘结强度，则建议用于大坝安全分析的适当的表观粘结强度值。所开发的数值模型将利用钻井岩心和较大尺度方形样品的剪切试验的现有结果进行验证和校准。还将根据这些结果提出和验证本构关系。为了调查尽可能接近实际坝址条件的坝岩界面，将使用光探测和测距(LiDAR)技术原位扫描实际岩基表面的3D剖面。将使用有限元对四个具有与扫描的基础表面相对应的足迹的重力坝整体进行建模。将对混凝土-岩石界面以及二维和三维大坝-岩石系统进行一系列参数分析。将提供指导方针，以表征规模效应以及接缝粗糙度和表观粘聚力对所研究混凝土大坝结构稳定性的影响。

The Dam Safety Act in Québec and its attendant regulation, which came into effect on April 11, 2002, require owners of high-capacity dams to regularly assess and monitor their structural behaviour under the effect of various loads. In this context, an appropriate understanding of dam-rock interaction is crucial for the assessment of the structural stability of concrete dams. The main objectives of this CRD research proposal are: (i) to develop an experimentally validated multiscale numerical model capable of predicting the values of apparent cohesion strength along dam-rock interfaces; (ii) to use the developed numerical model to carry out parametric analyses investigating the effects of apparent cohesion strength and dilation at irregular dam-rock interfaces on the sliding stability of actual concrete dams; (iii) to exploit the results obtained to develop new constitutive relations which can be implemented in software currently used at Hydro-Québec to conduct dam stability analyses as required by dam safety regulations; and (iv) to propose appropriate apparent cohesion strength values to be used for dam safety analyses if the obtained results clearly demonstrate that apparent cohesion strength is to be considered at dam-rock interfaces. The developed numerical models will be validated and calibrated using available results from shearing tests of drilled cores and larger scale square samples. Constitutive relationships will also be proposed and validated based on these results. In order to investigate dam-rock interfaces as close as possible to real dam site conditions, 3D profiles of actual rock foundation surfaces will be scanned in-situ using Light detection and ranging (LiDAR) technology. Four gravity dam monoliths with footprints corresponding to the scanned foundation surfaces will be modeled using finite elements. A series of parametric analyses of concrete-rock interfaces as well as 2D and 3D dam-rock systems will be conducted. Guidelines will be provided to characterize scale effects and the influence of joint roughness and apparent cohesion on the structural stability of the studied concrete dams.