Research on Roadway Surrounding Rock Loose Circle Change Law Under Multiple Blasting Vibrations

In order to explore the roadway surrounding rock loose circle change law under multiple blasting vibrations, we measure the surrounding rock loose circle range by single-hole ultrasonic testing technology after each blast. According to the results of the test, we determined that the loosing circle size after the blasting of the eight times increased 2.25% averagely compared to that before the blasting. The final scope of roadway surrounding rock loose circle is about 1.14 meter. Results indicate that: under the action of the repeated blasting vibration wave in the cycle, loose circle are rising. However, it is not every blasting vibration can cause the change of the surrounding rock loose circle. Meanwhile, for far from center of explosion, the influence of loose blasting vibration on the measuring point circle is random, which has no correlation with distance from center of explosion.