统一框架下的软硬岩土连续-非连续变形分析的关键问题

软硬岩土在变形特性和破坏机理方面都存在巨大的差别：软弱岩土在较低应力水平下就会出现塑性变形，破坏一般是伴随着塑性累积变形而导致的剪切带的生长直至贯穿，破坏前变形明显；硬岩在工程应力范围内呈弹脆性，破坏是为因裂纹的萌生、扩展而导致的断裂，破坏前无明显的征兆。.对于硬岩，弹脆性模型基本上描述了其变形和破坏特征。有成熟的数值方法能够模拟裂纹的萌生、扩展直至断裂，如数值流形法。.对于软弱岩土，将采用剪切带的强间断模型，即将其简化成一个无厚度的位移间断面，这样就可以向硬岩那样实现从连续到非连续变形的统一求解。.将推导闭合位移间断面尖端区域的渐进位移场，建立反映位移间断面演化的变分不等式模型和相应的求解方法；探明应变能和位移间断面上的耗散能之间的竞争机制。最后，通过模型试验加以验证并进行工程实例分析。.研究成果可消除应变软化本构所导致的网格依赖性，完善临界状态土力学的变形分析理论。

Difference in hardness of geomaterials leads to huge discrepancy in deformation features and damage mechanism. Soft geomaterials experience plastic deformation under lower stress level; damage is caused by the growth and penetration of shear bands resulting from accumulated plastic deformation, and considerable deformation can be observed prior to damage. Hard rocks take on elastic-brittle behaviors under the normal stress level; damage is due to fracture caused the initiation and propagation of cracks, with no obvious deformation observed..For hard rocks, an elastic-brittle constitution relationship is basically able to describe features of deformation and damage, there are mature numerical methods, such as the numerical manifold method to be applied in the proposed project, to simulate the initiation, growth till fracture..For soft geomaterials, the strong discontinuity model is applied, where a shear band is simplified a displacement discontinuity. In this way, it can be realized as hard rocks that the analysis from continuous deformation through damage is carried out..In this study, the asymptotic displacement field near the tip of a closed displacement discontinuity is derived. The variational inequality model for the evolution of displacement discontinuities is built and the algorithm for it is developed. The mechanism of competence between strain energy and dissipative energy in displacement discontinuities is ascertained. Finally, the proposed methods are verified using model tests, with applications to practical examples..It is expected that mesh dependency due to the application of strain-softening constitution relationship is resolved, and the deformation analysis based on the critical state soil mechanics is improved.