现代土力学研究的新视野——宏微观土力学

随着岩土工程领域的不断拓展,特别是在深地、深海、深空工程("三深工程")方面需要面对更多复杂的岩土材料和环境条件。基于连续介质和唯象的常规土力学理论与方法在描述岩土材料的非连续性、大变形和破坏等复杂特性以及复杂环境影响上有许多缺陷。宏微观土力学力图从本质上探求岩土材料复杂宏观特性的微细观机理,建立其多尺度分析理论与方法,解决岩土力学与工程中的疑难与关键问题,从而帮助提高工程设计水平。本文回顾了宏微观土力学近40 a的发展历程,从宏微观土力学的研究方法、理论和应用等方面综述了国内外学者的主要研究成果,包括典型土体的微观特性、微观本构理论、宏微观关联、基于微观机制的宏观本构理论等。研究土体包括陆地上黏土、结构性砂土、黄土、深海能源土和太空土(月壤)。重点阐述了宏微观土力学的重要研究手段之一的离散单元法在模拟陆、海、空疑难岩土力学与工程中的应用与拓展,探讨了宏微观土力学研究所面临的各种挑战和重大机遇。通过系统介绍上述研究成果,勾勒了宏微观土力学的基本框架,以期推动该研究方向的加速发展。

New paradigm for modern soil mechanics: Geomechanics from micro to macro

With the continuous advances in geotechnical engineering practice,especially in deep-underground,deep-sea and deep-space areas(engineering of three-deep-area),geo-engineers are faced with increasingly complex geomaterials and geotechnical environment.Based on the continuum mechanics and phenomenological methodologies,the conventional soil mechanics encounters many difficulties in describing the complicated behavior of soils,such as discontinuous response,large deformation and failure,and the impacts of complex environment.Geomechanics from micro to macro(GM3) starts from particle-scale characterization of soils and upscales to its macroscopic behavior.In this way,the microscopic mechanisms can be revealed to understand the complex behavior of problematic soils.Then the multi-scale theories and methodologies established can promisingly solve the key problems in geomechanics and geotechnical engineering and finally upgrade engineering design level.This paper first highlights the main development of GM3 in the past 40 years.The methodologies,theories,applications of GM3 developed by the worldwide researchers are then introduced,including microscopic behavior of typical soils,microscopic constitutive models,micro-macro bridging and macroscopic constitutive models based on the micro-mechanisms.Various soils are discussed,including clays,structured sands and loesses on the earth,deep-sea methane hydrate bearing sediments,and planetary soils(lunar regolith).The focus is put on the applications and extensions of distinct element method(DEM) in the simulations of problematic geomaterial mechanics and geotechnical engineering on and off shore and in the deep-space.Finally,serveral key challenges and opportunities in GM3 are discussed.By systematically reviewing the above achievements,the paper outlines GM3 framework in order to accelerate the development of research in this area.