Research on expansion process of blasting stress waves causing cracks in
rocks with filled joints
Abstract
Joints in medium has a significant influence on transmission of blasting
stress waves and expansion of blast-caused cracks. This paper first
carries out an experiment on crack expansion in PMMA medium with
vertically filled joints under blasting load by using the Digital Laser
Dynamic Caustics testing system (DLDC), makes an analysis on beginning,
expanding and ending of wing cracks, studies variation of dynamic stress
intensity factor and crack expansion velocity on crack tip. Then it
makes an effective inversion to stress wave transmission and crack
expansion in the test by using the Distinct Lattice Spring Model(DLSM),
makes a comparison on stress variation at center points on wave heading
side, back side and endpoints of the joint, makes an analysis on
characteristics of stress wave impact. Finally it compares and analyzes
expansion velocity/acceleration difference of wing cracks with different
joint characteristics(filled, open, closed, bedding).