Researches on the Effect of Tamping
Yataro SHIMOMURA · Journal of the Mining and Metallurgical Institute of Japan · 1954
It can be shown analytically that both the efficiency of explosives and the stresses in the rocks surrounding the shot hole due to the explosion pressure within the hole would be greatly increased by the.use of good stemming materials.There are two factors to prevent the stemming from being ejected by the explosion.One of these is inertia and the other is the frictional resistance of the stemming, but the effect of the stemming is greatly affected by the latter.It has been found by experiments on the relation between time required to blowing out the stemming from the shot hole by the explosion and the length of the stemming that the dynamic resistance of the stemming is similar to the result by the static experiment. The minimum length of sand stemming necessary for shots is recommended. to be 40cm for soft rocks and 60cm for coal and hard rocks.