报告题目
滑坡和泥石流中的流体动力学
（Hydrodynamics of landslides and debris flows）
时 间
2018年5月12日下午3:00-5:00
地 点
浙江大学紫金港校区安中大楼一楼
安中报告厅
报告人
斯坦福大学 Ronaldo I. Borja教授
报告简介
降雨和地震可以从多方面减弱边坡抵抗破坏的能力。对非饱和边坡，降雨增加了土体饱和度，破坏了粒间表面间的连接，当入渗量足够大时，会在土体内形成水流，并在土体上施加顺着坡面向下的拖拽力，降低边坡的稳定性。对饱和、或饱和度较高但未达到100%的边坡，地震作用会导致瞬时孔压上升，土体强度降低。此外，地震产生的惯性力也对土体提出了新的要求，即土体应能抵抗该作用力。本讲座将介绍一个可用于地震或降雨诱发边坡破坏的连续介质物理模型，重点阐述边坡破坏的诱发机理、流体特性，以及随后的岩土体运动特点；此外还将探讨有限元法和光滑粒子流体动力学(SPH)的无网格法在研究诱发滑坡、泥石流等机理方面的潜力。
报告人简介
Ronaldo I. Borja教授主要从事固体力学、岩土力学和地球科学等领域的理论研究和数值计算工作。在斯坦福大学，他教授本科生《岩土工程》课程、硕士研究生《力学和有限元法》课程，以及博士研究生《计算塑性力学》和《计算渗流力学》课程。他的研究包括利用强间断和扩展有限元方法研究多尺度不连续裂纹扩展；饱和及非饱和多孔介质中固体变形-流体扩散等多场耦合的求解方法；固/液相互作用和非线性接触力学的稳定有限元方法；以及页岩非弹性变形和断裂性质的纳米尺度表征。Borja教授著有《塑性建模与计算》教材（Springer出版），并担任两个顶级期刊的编辑，分别是Wiley出版的《 International Journal for Numerical and Analytical Methods in Geomechanics》和Springer出版的《Acta Geotechnica》。Borja教授因其在计算渗流力学方面的贡献获得2016年ASCE 莫里斯·比奥（Maurice A. Biot）奖章。
Introduction to the report
Rainfall and earthquakes weaken an earth slope in many ways. In partially saturated slopes, rainfall increases the degree of saturation of a soil, thereby breaking the bonds created by surface tension between soil particles. When the volume of infiltrating water is large enough to mobilize fluid flow inside the soil matrix, a downhill frictional drag is exerted by the fluid on the sediment, creating a destabilizing effect on the slope. In fully saturated slopes, or even when the degree of saturation is not exactly 100 percent in the soil, an earthquake could cause momentary pore pressure buildup and reduce the frictional strength of the soil. Furthermore, the inertia load generated by an earthquake creates an additional demand that could test the capacity of the soil to resist failure. In this talk, he will present a physics-based framework for continuum modeling of slope failure induced either by an earthquake or by rainfall. His talk will focus on both the triggering mechanisms leading to slope failure, and the subsequent flow mechanisms characterizing the movement of earth materials at post-triggering. He will also discuss the potential of the finite element method and a meshless method called smoothed particle hydrodynamics (SPH) for capturing the triggering and post-triggering failure mechanisms in earth slopes, including that of debris flows.
Introduction to the Lecturer
Professor Ronaldo I. Borja works in theoretical and computational solid mechanics, geomechanics, and geosciences. At Stanford University, he teaches an undergraduate course in geotechnical engineering, a graduate course in mechanics and the finite element method, and two doctoral level courses in computational plasticity and computational poromechanics. His research includes the development of multi-scale discontinuity framework for crack and fracture propagation utilizing the strong discontinuity and extended finite element methods; solution techniques for multi-physical processes such as coupled solid deformation-fluid diffusion in saturated and unsaturated porous media; stabilized finite element methods for solid/fluid interaction and nonlinear contact mechanics; and nanometer-scale characterization of the inelastic deformation and fracture properties of shales. Professor Borja is the author of a textbook entitled Plasticity Modeling & Computation published by Springer. He serves as editor of two leading journals in his field, the International Journal for Numerical and Analytical Methods in Geomechanics published by Wiley, and Acta Geotechnica published by Springer. Professor Borja is the recipient of the 2016 ASCE Maurice A. Biot Medal for his work in computational poromechanics.
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浙江大学曾国熙讲座基金会
2018年3月29日