Experimental Techniques To Reduce Blast Vibration Level, Tourah, Cairo, Egypt

摘要

There are four large limestone quarries, located nearby Cairo metropolitan. Drilling and blasting operations are used to extract limestone for the cement industries. In these quarries, the blast vibration should be kept below a certain limit. One of these quarries is Tourah Portland Cement Company (TPCC) limestone quarry which, lies near important and historical large caves, within Tourah Mountain. Therefore, control of blast vibration level becomes very critical. A series of multi-holes blasts have been performed to answer several questions about the optimum scaled distance that can be used safely to avoid caves damage, what constitutes true timing and initiation system?, and their relation to the blast vibration level?. Four Tri-axial geophones located in a linear array, over a distance of 1.0 km (0.621 miles) from the quarry faces, they have synchronized by means of a GPS timing reference. The data retrieved from the geophones and subjected to different steps of processing and analysis. The field tests showed that there was a significant difference in the blast vibration level between top and bottom initiation systems, containing the same explosive charge per delay intervals. In the upper bench, the results showed that the blast optimization of vibration level requires small delay intervals at distance more than 800.0 m (875 yards), between shot point and caves. This study helped TPCC limestone quarry to remain operating since the government permitted the continuation of blasting operations. In addition, the advantages of using chock tube system in comparison with electrical detonators, could lead to convince the government to raise the permitted explosive charge per day.