粉砂岩峰后破坏区应力脆性跌落的试验和本构方程研究  

Theoretical and Experimental Study on Siltstone Brittle Stress Drop in Post-Failure Region

作　　者：张黎明[1] 王在泉[1] 李华峰[1] 孙辉[1] 

机构地区：[1]青岛理工大学理学院,青岛266033

出　　处：《实验力学》2008年第3期234-240,共7页Journal of Experimental Mechanics

基　　金：国家自然科学基金资助项目(50674059);山东省教育厅资助项目(J07YB01)

摘　　要：对粉砂岩试样进行常规三轴压缩试验,得到了其在不同围压下的应力-应变全程曲线。结果表明,岩样应力-应变曲线峰前(破坏前区)部分的力学性质较为稳定,其力学行为可用经典强度理论进行描述;应力-应变曲线峰后(破坏后区)部分,岩样处于非稳定状态,其力学行为难以用经典强度理论来描述,而脆塑性模型恰好可以描述试验岩样的应力非连续变化特征。岩石的应力脆性跌落是有条件发生的,应力脆性跌落系数是围压的函数,并给出应力脆性跌落系数与围压的关系。对完整岩样而言,使用弹性-线性软化-残余塑性三线性非理想脆塑性模型可以描述岩样的本构特征,而对含有节理岩样而言,采用双线性弹性-线性软化-残余塑性四线型非理想脆塑性模型与试验更为相符。Complete stress-strain curve of siltstone specimens under different confining pressures were obtained through conventional tri-axes compression tests. Results show that the pre-failure region of specimens represents a stable mechanical response, which is well defined by classic strength principle. However, the post-failure region of specimens represents an instable mechanical response, which is difficult to describe by classic strength principle. To afurn, it can be described by brittle-plastic model. Results show that the coefficient of brittle stress drop is a function of the confining pressure. Relation function between the brittle stress drop and the confining pressure of siltstone was obtained. For intact siltstone, the linear elastic-linear strain softening-residual plastic model is well adapted. For jointed siltstone specimens, the bilinear elastic-linear strain softening-residual plastic model is even better adapted.

关 键 词：破坏后区 脆塑性 应力脆性跌落 

分 类 号：TU452[建筑科学—岩土工程]