具有多种断层结构岩样的形变和破裂特征的试验研究

Experimental Study of the Characteristics of Deformation and Fracture of Rock Block with Various Structure of the Fault

在岩石板上切割出多条切缝并以石膏填充,将其分为3个构造特征区:A区(断层交汇区)、B区(左行左列岩桥区)、C区(右行左列岩桥区)。采用双轴加压、定点应变、声发射信息系统和实时全息干涉计量方法(激光)进行观测研究。结果表明:在岩样破坏孕育过程中,各个特征区都出现了特大破裂。每个特大破裂发生前定点应变、激光干涉条纹图(应变场)和声发射信息都出现了特征变化。特大破裂的发生有先后,其前兆特征的出现也有先后,并且各区有各自的特点,某些前兆还可能在各区之间交替出现。研究认为,三个区的断层结构性质不同,这就导致了不同的破裂顺序,甚至产生不同的前兆现象。

V-shaped block boundaries consisting of en echelon faults（slots or prefabricated cracks）were cut in a coarse-grained granite board.The slots were filled with gypsum.According to the structural characteristics,the board was divided into three zones：Zone A（where the faults converge）,Zone B（where the faults form left-lateral and left-stepping rock bridges）,and Zone C（where the faults form right-lateral and left-stepping rock bridges）.An observational study was made by means of biaxial loading,fixed-point strain measurement,AE information system,and real-time holometry（laser）.Results are as the following：All extra-fractures emerge in various structural zones during process of preparing failure of the sample.Before extra-fracturing,the variation characteristics such as the strains at measuring points increased with the increase of stress,message of AE events and fringes are observed by real-time holometry.Extra-fractures occurred in order,and the precursors of the extra-fractures emerged in order too.The three zones had their own characteristics with regard to the fracturing.Some precursors emerge alternately in various zones.When examined from the structural characteristics,it can be seen that the three zones are places where different structures meet and therefore are sensitive sections for events to occur.This has led to different orders of fracture or even resulted in different precursors.