软岩料高填方路基工后长期变形宏细观机理研究

Nowadays more and more high embankments, which is mostly composed of soft rock fills, are constructed in West China. However, there is not yet a resonable theory to describe the long-term deformation behavior of soft rock fills. A substantial amount of experimental evidence shows that the long-term deformation of soft rock fills depend upon their internal fabric features, and the classical continuum mechanics is not applicable to represent the inherent behavior of soft rock fills. By means of the indoor test, theoretical investigation and numerical simulation, a research method is applied to study the long-term deformation of high rockfill embankment in the macro-mesoscopic scale in this project. At first, mechanism of particle breakage in soft rock fills will be investigated through a series of rheological tests. And next, a fabric theory and two-scale constitutive model will be constituted by using some theoretical analysis of the test results, and at the same time a discrete-continuum approach will also be developed and incorporate into the finite element analysis (FEA). Finally, the feasibility of the theoretical results will be verified by some experimental evidence and measured results in the field. A large number of numerical simulations will be conducted to explore the mechanism of particle breakage of soft rock fills and the mechanism of post construction long-term deformation of high rockfill embankment. The research results in this project can present theoretical supports to resolve the troublesome problems, such as choice of soft rock fills, optimization of particle grading, prediction of long-term deformation and evaluation of safe operation of high rockfill embankments.

目前，我国西部软岩料高填方路基工程越来越多，然而迄今为止尚未有成熟理论能够全面和合理地描述软岩料长期变形特性。研究表明，仅从宏观层面采用经典连续介质理论，无法反映软岩料长期变形行为决定于内部结构特征的固有特性。本项目采用室内试验、理论研究和数值模拟相结合的研究方法，从宏、细观层面研究软岩料高填方路基长期变形性质。基于室内试验开展软岩料细观破碎机理研究，基于理论分析开展软岩料组构描述方法与两尺度本构模型研究，并开发连续－离散有限元模拟技术。理论成果经过验证后用于实体工程数值仿真分析，全面探讨软岩料颗粒破碎细观机理及其高填方路基工后长期变形一般规律。研究成果可为解决山区高填方路基软岩料选用、级配优化设计、长期变形预测与运行安全评估等关键技术问题提供理论支撑。

当前我国交通建设不断向山区延伸，软岩料高填方已成其路基基本形式。本项目采用室内试验、理论分析和数值模拟相结合的研究方法，从宏/细观两个层面研究了软岩料高填方路基工后长期变形性质。通过室内试验，分析获得了软岩料颗粒破碎演化规律及其与宏观蠕变的内在联系；基于理论分析，构建了反映颗粒破碎对软岩料剪胀、软化和蠕变特性影响规律的弹黏塑性本构模型；通过数值模拟，分析获得了软岩料高填方路基填筑与运营全过程的应力变形时空演化规律；基于机理分析，揭示了软岩料蠕变时间尺寸效应及其高填方路基工后长期变形的细观机理。研究成果丰富了粗粒土工程性质与本构描述研究内涵，在规范化处理后即可用于解决山区高填方路基填料选用、级配优化设计、长期变形预测与运行安全评估等工程技术问题。