Performance of the Explosion Test Under Sand

Two methods may be applied to obtain the volume of the crater. One uses the formula V i = 7T abh/12 

The value of V i derived from a, b and h is generally larger than V s, the measure of the sand used to refill the crater. This may arise from the change in the height of sand around the crater after the explosion. The difference between the two methods is not great and the simple measurement suffice. However if the use of extra charge or insufficient charge results in a non-ellipti crater, the value of the volume derived from the measurements of a, b and h may not be correct Also if the sand under the steel tube is too hard, the conical crater cannot be formed. If the sand becomes hard, the 

The relationship among equivalent depth (d/W 1/3 ) of explosive under the sand, the weight of the explosive (W) and the volume of the crater formed is shown in Fig.3.131. The location of the explosive and the representive shapes of craters are illustrated in Fig.3.130. 

The data in Fig.3.131 show that the volume of the crater is greatest when the equivalent depth is about 0.5m. If 100 g of Airemite is used, a regular cone crater can be formed if the explosive is planted at a depth of 10 30 cm if 50 g, at a depth is 10 20 cm, and if 200 g, at a depth is 20 40 cm. For the 50/60 steel tube test, a depth of 60 cm is reasonable. 

When the explosive mass increases, the depth will become deeper than fitting charge. This is because that the deeper of explosive, the weaker of explosion noise, and the effect of closed extent From these observations the following standard depths are suggested  

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