基于数字图像处理技术的溶蚀岩体细观变形破坏机制模拟研究

Simulation on mesoscopic deformation and failure mechanism of dissolved rock mass using digital image processing technology

通过数字图像处理技术对广泛发育于岩溶地区的溶蚀岩体的溶蚀特征进行提取,构建离散元溶蚀岩体模型,并模拟单轴压缩试验研究溶蚀岩体的细观变形破坏机制,以分析溶蚀岩体的变形破坏特征和裂隙演化规律。结果表明:溶蚀岩体模型能够很好地表征岩体的溶蚀特征,对真实的溶蚀形态具有较好的还原作用;溶蚀岩体的累计破坏数曲线呈现“S”型变化特征,即分为裂隙不发育阶段、稳定发育阶段和不稳定发育阶段,溶蚀岩体的破坏具有累进性特点;由于溶蚀孔洞的存在,使得溶蚀岩体接触力力链表现出各向异性特征,随着加载的进行,岩体骨架为抵抗外部荷载的作用,导致接触力在岩体骨架内集中,表现为接触力力链线条变粗;随着应变的增加,试样发生起源于溶蚀孔洞周围的破坏,破坏区域发生卸荷作用,接触力力链被淡化,最终试样发生破坏,力链消失,溶蚀岩体应力应变关系是试样内部接触力变化规律的宏观表现。

The dissolved rock mass is widely distributed in southwest China,of which deterioration of the mechanical properties can cause geological hazard in special conditions.Due to the particularity of its material composition and structural characteristics,it is difficult to collect samples of dissolved rock mass and conduct laboratory tests.To solve this problem,taking a project slope in Guizhou Province as an example,this work extracts dissolution information from this rock mass using the digital image technology.Firstly,the morphological characteristic parameters of the dissolved rock mass are obtained by digital image processing technology,and then the discrete element model of the dissolved rock mass is constructed on the basis of parameter calibration,finally,the deformation and failure characteristics and fracture evolution law of the dissolved rock mass are analyzed by the uniaxial compression numerical test.The results show that the stress-strain curve of dissolved rock can be divided into three stages,elastic deformation stage,stable deformation stage and failure stage.The stress-strain relationship of dissolved rock mass is the macroscopic manifestation of the change law of the contact force inside the specimen.The failure of dissolved rock mass is progressive.Because of the existence of dissolved holes,the contact force chain of the dissolved rock mass shows anisotropic characteristics.As the load increases continuously,the external load is mainly borne by the rock skeleton,which shows that the range of contact force chain increases continuously.With the increase of strain,the failure began to occur around the dissolved hole of the specimen,and then the failure area continued to expand,and the contact force chain scope continued to decrease,eventually,the failure occurred in the specimen and the force chain disappeared.The model of dissolved rock mass based on digital image processing technology can well represent the characteristics of dissolved rock mass.Moreover,the mesoscale deformation and failure mechanism of dissolved rock mass is of great guidance and practical significance to the study of geological disasters such as karst collapse and rock avalanche.