摘要
采用卸载状态岩石的力学参数和相应的强度准则,描述卸荷岩体的力学性质可能存在一些不足之处。为了能够从理论上更准确地分析卸荷岩体的力学性质,从弹性应变能出发对卸荷岩体力学性质的演化进行了探讨,研究了岩体的开挖卸荷与卸荷试验中试样初始损伤程度的不同之处和弹性应变能、应力偏量第二不变量、应力张量第二不变量和泊松比内在关系,简要地分析了现有强度准则在描述卸荷岩体力学性质方面的不足之处。以弹性应变能为基础采用加载状态的岩石力学参数,对岩石的卸荷力学特性进行了理论分析与试验验证。结果表明,现有的大多数强度准则难以描述试样卸荷破坏时强度特征,且可能存在不满足能量守恒定律的情况;基于弹性应变能强度准则既可得到表征卸荷破坏时岩石的强度提高,又可以描述强度的减小。文中分析了产生上述结果的本质机理。
The mechanical features based on unloading mechanical parameters are not accordant with the mechanical characteristics of rock under unloading condition; in order to construct strength criterion which is widely used and accordant with characters of unloading rock, the work and results are carried out as fellows. Firstly, different initial damage levels between unloading experiment of rocks and underground engineering under excavation unloading conditions are discassed. Secondly, the internal relations between elastic strain energy, the second invariant of stress deviator, the second invariant of stress tensor and Poisson's ratio are explored. Thirdly, the internal relations between elastic strain energy and strength criterion are also explored. Lastly, based on elastic strain energy, the mechanical features of rocks under unloading condition are studied by using loading mechanical parameters. The experiment results show that existed strength criterion is possible to violate the first thermodynamic law or the law of conservation of energy. It is suitable to increase or decrease for the limited bearing loads of rock under the range of unloading condition based on elastic strain energy, and the mechanism of above-mentioned result is analyzed.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第S2期123-130,共8页
Rock and Soil Mechanics
基金
国家自然科学基金创新群体基金(No.50921063)
贵州省科学技术基金项目(No.黔科合J字[2015]2037号)~~
关键词
卸荷力学特性
弹性应变能
泊松比
应力张量第二不变量
unloading mechanical characteristics
elastic strain energy
Poisson's ratio
second invariant of stress tensor
