Quantitative Observation of the Micromechanics of the Brittle-Ductile Transition in Rocks

破坏机制从脆性断裂到塑性流变的转变对理解构造物理、地壳强度和野外变形方式具有重要意义。最近在三个领域的研究已经对脆性-塑性转变的物理和力学产生了新的见解：获得高质量的力学数据，变形微观结构的系统观察，以及岩石在压缩中破坏的理论模型的进展。定性的微观结构观察提供了各种变形机制运行条件、应变分配估计和裂纹成核机制识别的信息。PI将通过对方解石、钙长石、橄榄岩和辉绿岩等天然和合成岩石进行三轴力学测试，继续研究脆性-韧性转变。定量的微观结构分析是了解变形微观力学的重要组成部分。声发射测量也将在一些选定的实验中进行，并且在测试期间将进行轴向和体积应变测量。

The transition in failure mechanism from brittle fracture to plastic flow is important in understanding tectonophysics, the strength of the crust, and the style of deformation at the field scale. Recent studies in three areas have yielded new insight into the physics and mechanics of the brittle-plastic transition: acquisition of high quality mechanical data, systematic observations of deformation microstructures, and advances in the theoretical modeling of the failure of rocks in compression. Qualitative microstructural observations have provided information on the conditions under which various deformation mechanism operate, estimates of strain partitioning, and identification of crack nucleation mechanism. The PI will continue work on the brittle-ductile transition by performing triaxial mechanical tests on natural and synthetic rocks of calcite, anorthite, peridotite, and diabase. Quantitative microstructural analyses to understand the micromechanics of deformation are an important part of this study. Acoustic emission measurements will also be performed on a selected number of experiments, and axial and volumetric strain measurements will be made during the tests.