冻融循环作用下主控结构面强度渐进劣化机理

The major controlling structural plane play critical role in rock slope stability analysis. Especially under freezing-thawing cycle effect, its strength is deteriorating progressively, which can induce series of geological hazards such as landslides and rock collapses. Using transfixion and non-transfixion controlling structural plane under the effect of freezing-thawing cycle as our main research objects, their geometrical characteristics are extracted and the generalized models are established. Duplicating the climate features in field as our lab experimental environment, a series of freezing-thawing cycle experiments, mechanical tests and micro-damage tests are designed in order to acquire the freezing-thawing deterioration regularity of the peak strength, freezing-thawing evolution of geometrical morphology characteristics, and micro-damage of both rock walls and bridges, of the major controlling discontinuities. Through the analysis of the experimental results, the mathematical model of freezing-thawing deterioration of discontinuity peak strength is established. The structural plane strength criterion under freezing-thawing cycle effect is determined, the damage evolution procedure of non-transfixion discontinuities is revealed and the rock bridge fracture initiation criterion under freezing-thawing cycle is investigated. Numerical modeling and field application will both be conducted in order to verify and revise the research results. Finally the system of progressive deterioration mechanism of the strength of major controlling structural plane under freezing-thawing cycle effect will be worked out. This research result will have important theoretical significances to slope stability analysis, slope design and geological disaster prevention and control in cold region. It can also provide technical supports for the plenty of cold region rock engineering projects in Western Development.

主控结构面是岩质边坡稳定性的重要决定因素，在冻融循环作用下易导致其强度渐进劣化，诱发滑坡和崩塌等地质灾害。本项目针对受冻融循环作用的寒区岩质边坡，选取主控结构面中贯通性结构面、非贯通性结构面为研究对象，进行几何特性提取和模型概化；以现场气候特征为试验条件，进行冻融循环试验、力学试验和细观损伤测试，获得主控结构面峰值强度冻融劣化规律、几何形态冻融演化特征、壁岩及岩桥细观损伤特点；通过对试验结果的理论分析，建立结构面峰值强度冻融劣化数学模型，确定冻融作用下结构面强度判据，揭示非贯通性结构面冻融损伤演化过程，建立岩桥冻融起裂判据；通过数值试验和现场应用进行成果的检验和修正，最终形成冻融循环作用下主控结构面强度渐进劣化机理的理论体系。研究成果对寒区边坡稳定性分析、工程设计和灾害防治具有重要的理论意义，能为国家西部大开发战略中涉及的大量寒区岩体工程建设提供理论指导和技术支持。

主控结构面力学性能是岩质边坡稳定性的重要决定因素，冻融循环作用下易导致其强度渐进劣化，诱发滑坡和崩塌等地质灾害，因此，探讨冻融循环条件下主控结构面的力学行为对分析寒区边坡工程稳定性具有重要的科学意义。项目以寒区岩质边坡为工程背景，在结构面特征统计分析与模型概化的基础上，综合采用室内外试验、理论分析和数值模拟等方法和手段，围绕冻融循环作用下主控结构面强度渐进劣化机理的相关问题展开研究。.研究首先通过试验在比较几类岩石抗冻性特点基础上，选择砂岩为研究对象，获取不同冻融次数下完整岩样的物理力学参数和破坏特征，借助数字图像技术和分形理论，揭示红砂岩的力学性能劣化规律、宏观破坏特征及其断口表面分形维数变化规律和损伤劣化机理，建立了冻融砂岩单轴压缩分形损伤本构模型；在此基础上，以砂岩为对象，进行了类砂岩材料的配比方案及冻融特性研究，设计了不同相似材料的配比方案，测定冻融前后类岩石物理力学参数，分析类岩石和原岩的冻融劣化机理，确定与砂岩抗冻性近似的相似配比；研发制备砂岩贯通性结构面的劈裂工具，制备结构面并完成定量表征。采用力学实验与三维激光扫描技术，获得了贯通结构面峰值强度冻融劣化规律及其几何形态冻融演化特征，通过数据统计及理论分析，揭示贯通结构面峰值强度冻融劣化规律，建立峰值强度冻融劣化数学模型，探讨强度劣化机理并修正巴顿经典强度公式，建立结构面冻融强度判据；制备单一裂缝的非贯通性结构面，进行了冻融循环试验和冻胀力实时测试，获取了冻融过程中冻胀力变化曲线，研究了冻胀力随温度变化规律，结合CT扫描，分析了冻胀变形机理，以及裂缝随冻融循环扩展贯通的规律。.项目研究成果对寒区边坡工程设计和灾害防治具有重要的理论意义和学术价值，能为国家援疆、援藏和西部大开发战略中涉及的寒区岩体工程建设提供理论指导和技术支持。