考虑表面形貌特征的岩体结构面蠕变特性

工程岩体开挖会遇到各种复杂应力条件,岩体在荷载作用下随时间会产生流变现象,这种“累进性破坏”导致工程岩体常出现滑坡、塌方、大变形和支护困难等问题.为解释天然岩体结构面的流变现象,以天然红砂岩结构面为研究对象,基于结构面三维形貌扫描试验、结构面分级加载剪切蠕变试验,对天然岩体结构面的剪切蠕变特性进行系统研究.研究发现,岩体结构面蠕变变形量与蠕变应力和结构面三维形貌特征指标正相关;岩体结构面蠕变曲线可分为3个阶段,即过渡蠕变、稳态蠕变和加速蠕变阶段,当法向应力一定时,结构面三维形貌特征指标越大,发生的蠕变破坏越剧烈;基于结构面剪切蠕变曲线与剪切蠕变速率曲线特征,建立了参数物理意义明确的岩体结构面剪切蠕变经验模型. 

Shear Creep Characteristics of Red Sandstone Discontinuities Considering Different Morphologies

Engineering rock excavation will encounter a variety of complex stress conditions, and the rock will produce rheological phenomena over time under a loading effect. The "progressive damage" leads to landslides, collapses, large deformations and support difficulties in the engineering rock. In order to explain the rheological phenomena of natural rock discontinuities, the shear creep characteristics of the discontinuities of red sandstone are systematically studied based on the three-dimensional morphological scanning test and the graded loading shear creep test. It is found that the amount of creep deformation of the discontinuities is positively correlated with the creep stress and the three-dimensional morphological parameters of the discontinuities. The creep curve of the discontinuities can be divided into three stages, i. e. transition creep, steady-state creep and accelerated creep stage. When the normal stress is certain, the larger the three-dimensional morphological parameters of the discontinuities, the more intense the creep damage occurs. Based on the characteristics of shear creep curve and shear creep rate curve of the discontinuities, an empirical model of shear creep of the discontinuities is established with clear physical meaning of parameters.