正反向直剪下层状岩体强度和破坏特征模型试验  

Model tests for strength and failure characteristics of forward and reverse shear rock masses

作　　者：刘伟[1] 曾亚武[1] 夏磊[1] 陈曦[1] LIU Wei;ZENG Yawu;XIA Lei;CHEN Xi(School of Civil and Architectural Engineering,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院

出　　处：《武汉大学学报（工学版）》2019年第7期600-609,共10页Engineering Journal of Wuhan University

基　　金：国家自然科学基金项目(编号:41772308,41272342)

摘　　要：通过对不同倾角类层状岩体试样的正、反向直剪试验,深入对比分析了试样在正、反直剪过程中的抗剪强度、强度各向异性、剪胀性质和破坏形态的特征及不同.试验结果表明:1)层状岩体的剪切破坏,具有延性破坏特征;相同试样正、反向直剪的剪切应力与切向位移关系曲线特征点的变化规律一致,但曲线形态并不相同.2)同一法向应力下,相同试样正、反向剪切的峰值强度、残余强度和抗剪强度指标c、φ值均不相同.正向剪切时,30°的抗剪强度最高;而反向剪切时,120°的抗剪强度最高.3)相同层理倾角的试样正向剪切时,剪胀效果显著强于反向剪切时的;而反向剪切时的剪缩效果却比正向剪切时的更加明显.4)各组试样在正、反向剪切下的宏观破坏形态特征完全不同,有较强的剪切方向性.试样的剪切破坏机制可分为4种:滑移、剪断、张拉断裂和张拉滑移复合破坏.最后,通过简化计算模型的对比分析,在理论上解释了60°倾角的试样正、反向直剪时破坏机理的不同.The shear strength, strength anisotropy, dilatancy and failure characteristics of the specimen in the course of the positive and the reverse shear are analyzed by the direct and reverse shear test of different inclinations, and compared their differences. 1) The shear failure of layered rock mass has ductile failure characteristics. The change of shear stress and tangential displacement curve of the same specimen is the same;but the curve shapes are not the same. 2) Under the same normal stress, the peak intensity, residual strength and shear strength of the positive and reverse shear layers of the layered rock are different. In the forward shear, the shear strength is the highest at 30 °. While in the reverse shear, the highest shear strength is at 120 °. 3) When the specimens with the same bedding angle are sheared, the effect of dilatancy is stronger than that in the reverse shear;while the shear effect in the reverse shear is more obvious than that in the forward shear. 4) The macroscopic failure modes of the specimens in the positive and reverse shear are completely different and have strong shear direction. The shear failure mechanism of the specimen can be divided into four types: slip, shear, tension and tension slip. Finally, by simplifying the comparative analysis of the calculation model, the damage mechanism of the 60 ° dip angle is explained theoretically.

关 键 词：岩石力学 层状岩体 直剪试验 剪切方向 抗剪强度 破坏机制 

分 类 号：TU45[建筑科学—岩土工程]