冻融损伤土体的颗粒破碎及临界状态特性研究

With the purpose to meet the strategic demands for the development of mountainous area of Southwest China and clarify the basic research objectives of mountain hazards of Southwest China, the key study in this project should focus on the characteristics of particle breakage and critical state of soil subjected to the long-term freeze-thaw damage in Tibetan Plateau and its surrounding cold area, which has not been involved in the past studies. By conducting the freeze-thaw cycle tests of soil to produce the freeze-thaw-damaged soil and the laboratory tests of soil subjected to freeze-thaw damage, it is to investigate the characteristics of deformation behavior, particle breakage and mechanical behavior of soil subjected to freeze-thaw damage with proposing a freeze-thaw damage index to quantify the extent of freeze-thaw damage of soil. And the relation of the freeze-thaw damage index and particle breakage would be established in investigation. The characteristics of critical state of soil subjected to freeze-thaw damage would be analyzed in detail with an aim to establish three-dimensional critical state surface and its constitutive model in considering the influence of freeze-thaw damage on soil behavior. In addition, a method would be established to evaluate the stability of soil subjected to freeze-thaw damage. The findings in this study would be invaluable to enrich the theory of soil mechanics with providing the theoretical support and scientific guidance for deformation and failure mechanism of soil subjected to the long-term freeze-thaw damage in Tibetan Plateau and its surrounding cold area.

本项目面向国家西南山区开发战略需求，明确西南山地灾害基础性研究目标，以长期遭受冻融损伤的青藏高原及其周边寒区土体颗粒破碎与临界状态特性为研究核心,且相关研究尚未见报道。本项目，拟通过试样冻融循环试验及冻融损伤后土体的室内试验，提出一种能够全面而精确量化土体冻融损伤程度的冻融损伤因子，揭示遭受冻融损伤土体的变形、破碎及力学特性，构建土体冻融损伤因子与土体颗粒破碎之间的内在关系，分析冻融损伤土体的临界状态力学特性，构建可以考虑冻融损伤效应的三维临界状态面及本构关系，最终建立一套冻融损伤土体的稳定性评价方法。其研究成果将丰富土力学理论，为长期遭受冻融循环的寒区土体变形与破坏机理提供理论支撑与科学指导。

面向国家西南山区开发战略需求，明确西南山地灾害基础性研究目标，以长期遭受冻融损伤的青藏高原及其周边寒区土体颗粒破碎与临界状态特性为研究核心，本项目通过试样冻融循环试验及冻融损伤后土体的试验研究，揭示了冻融损伤土体的强度-破碎特性，阐明了复杂条件下冻融损伤土体的颗粒破碎特性及演化规律，破解了冻融循环的冻融损伤土体的临界状态特性，构建了可以考虑冻融损土体颗粒破碎的三维临界状态面和变形破坏演化规律，破解了颗粒流摩擦-碰撞颗粒破碎机理。相关研究成果将丰富岩土力学与灾害理论，为长期遭受冻融循环的寒区土体变形与破坏机理提供理论支撑与科学指导。