摘要
采用室内试验和理论分析相结合的方法,对有厚度天然结构面的法向循环加载变形特性进行研究。研究的天然结构面属平直稍粗型,厚2~3 mm,层间充填以岩屑为主,夹少量泥,母岩为灰岩。首先,对工程作用下的结构面应力演化过程进行梳理,并根据对结构面法向应力-闭合变形曲线特征的总结,设计了室内试验的法向荷载应力路径。其次,介绍了取样、基本物理和力学特性测试以及试件制备,分别开展了单次和多次法向加、卸载试验,并对试验曲线特征和法向变形力学机制进行分析。然后,对结构面法向循环加载本构关系进行研究,认为当法向应力在20 MPa以内时,分别采用双曲线模型和考虑修正参数的改进双曲线模型,可较好地模拟不同荷载阶段时的结构面法向应力-闭合变形关系;同时,发现当法向应力进入高应力区间后(定义大于20 MPa的应力为高应力,低于20 MPa的应力为中低应力),试验数据呈现新的特点,试验变形值与模型预测值的差距越来越大。最后,分析了造成差异的可能原因,认为在研究高应力条件下的结构面法向变形特征时,采用天然结构面试样是必要的。
This study aims to investigate deformation characteristics of natural structural planes with a certain thickness under normal cyclic loading using laboratory tests and theoretical analysis. The studied natural structural planes are flat and slightly rough with a thickness of 2-3 mm. The host rock is limestone and the infillings are primarily rock fragments with a small amount of mud. Firstly, the variation process of normal stress applied on structural planes under engineering effect is summarized. The loading path for experiments is then designed based on the characteristics of normal stress versus closure deformation curve. Then, we present the sampling operation, experimental results of physical and mechanical properties of samples, and the preparation of testing specimens. The specimens are applied to conduct single cycle and multiple cycles of normal loading and unloading experiments. In addition, we summarize the testing curves and the normal deformation mechanisms of structural planes and study the constitutive relation of structural planes under normal cyclic loading conditions. It is found that, when the normal stress is within 20 MPa, the hyperbolic model and the improved one with the consideration of a modification coefficient can be used to well simulate the relation of normal stress versus closure deformation at various loading stages. Meanwhile, when the normal stress increases up to a high-stress level（i.e., the stress magnitude above 20 MPa is defined as high stress, but below that it is recognised as the range of mediate to low stress.）, new characteristics were observed from testing data. The discrepancies between predicted values and monitored results become increasingly greater. Finally, the probable reasons for new characteristics are analyzed. It is suggested that it is necessary to use natural samples to investigate normal deformation characteristics of structural planes under high-stress conditions.
作者
张雨霆
丁秀丽
邬爱清
卢波
ZHANG Yu-ting DING Xiu-li WU Ai-qing LU Bo(Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Yangtze River Scientific Research Institute, Wuhan, Hubei 430010, China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第10期2865-2872,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51209021
No.51539002
No.51379022)~~
关键词
有厚度天然结构面
法向循环加载
变形特性
本构关系
natural structural planes with certain thickness
normal cyclic loading
deformation characteristics
constitutive relation
