Experimental Research On The Development Mechanism Of Rock Crack Under Shock Wave Of Underwater Explosion

Underwater blasting technology has a history of more than 100 years,which is one of the important branches in the field of blasting after entering the 21 st century.In recent years,with the continuous development of China's economy,the construction scale of underwater blasting project is becoming larger and larger,and the construction environment is becoming more and more complex.Rock is also an important object of underwater blasting construction and theoretical research.Compared with the mechanism of rock fragmentation by land blasting,due to the existence of water medium,the impact time of underwater blasting is longer and the peak stress is higher,which also makes the damage of rock stronger by underwater blasting shock wave.So far,people still lack a clear and effective understanding of the rock fragmentation mechanism by underwater blasting.And one of the most important and difficult problems in studying the rock fragmentation mechanism in underwater blasting is to understand the propagation of internal cracks under blasting load.Therefore,this paper will study the propagation of cracks in underwater blasting rock.Through theoretical analysis,the basic failure modes of cracks in specimens are obtained.At the same time,the experimental method is used to change the distance from explosive charge to sample and observe damage effect of the sample at different explosion distances.In order to observe the propagation of internal cracks more clearly and intuitively,CT scanning technology in non-destructive testing is introduced to scan the experimental samples after explosion.The image data of different sections after explosion can be obtained,which can better observe the propagation of internal cracks under explosive load.Meanwhile,the damage effect of rock is measured by combining the ultrasonic measurement technology,so the damage degree can be evaluated by the damage value.The ANSYS/LS-DYNA dynamic analysis software was used to simulate the model under experimental conditions,which supplements and verifies the experiment,the peak pressure of shock wave propagating to the sample at different explosion distances is obtained.Comparing with the peak pressure calculated by empirical formula,it is found that the numerical value is close and the variation law is consistent.The simulation results are in agreement with the experimental results,which shows that the numerical simulation results are reliable and can be supplemented by experiments.