Aanalysis of Interaction of Stress Waves Between Column Charges for Presplit-cushion blast

On the basis of actual parameter of wall control blast in Nanfeng mine, China, the process of dynamic stress changing between two column charges was studied for the presplit-cushion blast by a recent holographic photoelasticity. In the experiment model, two holes are simultaneously detonated from both ends (four ignition points), the bottom of the holes are loaded more than other parts (heavy charge). Under the condition, four consecutive isochromatic fringe patterns at different time are aquired in one loading run. characterstics of the stress distributions are compared at different place and time in the holes. It is found that interaction types of stress wave are various along the holes. The stress wave which is formed by the interaction of earlier producing P wave and later S wave along a distributed line charge is most important part in all stress waves. Research indicates that heavy charge in the bottom of the holes is crucial to produce pres-plit-cushion effect of the bottom, "End Effect" doesn't affectt on strength of stress along linking line between the bottoms. chief field of the "End Effect" are also explained.