Experimental Study On Crack Propagation Characteristics Of Rock-like Material Containing Two Flaws Under Biaxial Compression

The rock mass is a geological structure composed of rock blocks and discontinuous joints(crcak).The rock mass exhibits obvious discontinuity,heterogeneous and anisotropism under the influence of various discontinuities on different scales,and its mechanical properties are quite complex.Under the geologic environment and engineering disturbance,the adjacent joint crcak propagation and mutual coalescence are the main failure modes of the engineering rock mass.Based on the study of rock-like material containing two flaws under biaxial compression,this paper studies the factors,stress characteristics and penetrating mechanism on the process of crack initiation,propagation and coalescence.The main research contents are as follows:(1)First,make two kinds of rock-like material containing two flaws,one with the flaw inclination angle of 15 °,30 °,45 °,60 °,75 °and the other with the inclined angle of 15 °,30 °,45 °,60 °,75 °,90 °,105 °,120°.Try to classify eight coalescence mode(T-1type,T-2type,T-3type,S-1type,S-2type,TS-1 type,TS-2 type,TS-3 type).(2)Based on the biaxial compression test of rock-like material containing two flaws,the effects of lateral pressure,flaw inclination angle and rock bridge liagament angle on the crack coalescence mode and specimen breaking rule are studied.(3)The stress characteristics of crack propagation in each rock bridge crack coalescence mode are studied respectively for 8 different rock bridge crack pass modes.The crack initiation stress(SI)crack coalescence stress(SC)and peak strength(Sp)are used to describe the corresponding stress value in the process of crack propagation,So as to study the propagation law of different crack types under biaxial compression.(4)Based on the strain measurement of the strain concentration at the tip of the pre-existing flaws,the mechanism of the initiation?propagation?coalescence of the T-type crack coalescence mode and the S-type crack coalescence mode crack is further analyzed.That is,by introducing the concept of “strain concentration coefficient” to quantitatively analyze the mechanism of the initiation?propagation?coalescence of different crack type.