Study On The Initiation And Propagation Rules Of Unequal Multiple Cracks In Rock

The original cracks in rock mass is a crack system coexist with multi-scale andinteraction cracks, the interaction between different scales crack affect the stabilityand wreck of rock mass. The initiation and propagation rules of crack and theinteraction between main crack and minor crack are studied by using of theoreticalanalysis, rock-like material test, Digital Speckle Correlation Method (DSCM) andnumerical simulation, the influence of crack angle, the length of rock bridge andminor crack on the rules of crack propagation and coalescence are gained. By using ofhigh-speed video system, the initial crack initiation point in rock-like materials isidentified during the experimental process. Based on the fracture mechanics, thestrength expression of I-II mixed mode unequal length crack initiation under tensioncondition is established. Through the analysis of the strength expression, the influenceof the rock bridge length, minor crack length and crack angle on crack initiationstrength are gained.