Mathematical, experimental, and computational modelling of failure, instabilities, and degradation in geomaterials

岩土材料被赋予了一种微结构，这使得建模变得困难，但由于它们在应力-应变行为中表现出的丰富性，研究起来很有趣。对这些行为的研究表明，岩土材料的破坏是由粒级(微结构)机制以及材料不稳定和退化等现象主导的。例如，砂体中强烈的粒间滑移和覆盖形式的材料不稳定可能导致局部剪切带内的大塑性变形局部化，该剪切带在砂体中传播，最终导致机制，从而破坏，如滑坡所见。这项拟议的研究开发了一种多尺度公式，通过纯粹的微观机械分析，深入到中观尺度上的颗粒活动细节，并回到宏观尺度上。其结果是一个嵌入了微观结构信息的本构模型，因此具有比连续介质塑性理论更高的分辨率。除了数学和数值方面的发展外，研究建议还将涉及广泛的物理模型和数值模型，以通过基准问题来验证建议的理论。最终结果是一个现代地质力学框架，在其中开发了一种计算工具，以高度自信地处理从周期性加载的桥台墙到遭受地质灾害的地质结构等广泛的岩土应用，在这些地质灾害中，材料不稳定和退化显然是破坏的先兆。

Geomaterials are endowed with a microstructure that makes it difficult to model, but yet interesting to study due to the richness that they display in their stress-strain behaviours. The study of such behaviours shows that the failure of geomaterials is dominated by grain level (microstructural) mechanisms as well as phenomena such as material instability and degradation. For example, material instability in the form of intense inter-granular slip and overriding in sand may lead to the localization of large plastic deformations inside a localized shear band that propagates in the sand mass to ultimately cause a mechanism, and hence failure as seen in landslides. The proposed research develops a multi-scale formulation that penetrates right down to details of grain activity at the meso-scale and back to the macro-scale through a purely micromechanical analysis. The result is a constitutive model that embeds microstructural information, and therefore has a much higher resolution than that offered by continuum plasticity theory. Besides mathematical and numerical developments, the research proposal will also involve extensive physical modelling in concert with numerical modelling for the validation of the proposed theory by using benchmark problems. The end result is a contemporary geomechanics framework within which a computational tool is developed to address, with a high level of confidence, a wide array of geotechnical applications ranging from cyclically loaded bridge abutment walls to geo-structures subjected to geohazards where material instabilities and degradations are clearly precursors to failure.