Study On Test Methods Of Blasting Stress Wave In The Cement Mortar Test Block

Testing the explosion stress wave in rock is a important way of the transmission feature of stress wave in rock. In recent decades, some researchers constantly explore the law of the stress wave in rock. Because of the test methods and other reasons, it is hard to find the process of rocks damaging completely and objectively. To cognize the methods of stress wave measurement comprehensive, optimizing cement mortar test block experiment, using the achievement to the real life, we research these issues in-depth. First of all, this article introduce ways of stress wave measurement, including dynamic photoelastic, moire interferometry, PVDF piezoelectric thin film and resistance strain gauge. Comparing these methods, then we choice ultra-dynamic strain test system. By means of summarize literature and the experimentation of explosion in cement mortar test block, we can conclusions are as following:Firstly, Methods:dynamic photoelastic only can be used as model, lacking in strength to solve practical problems; The high frequency grating in moire interferometry is costly; PVDF can not be used to test wave form of stretching strain.So we choice esistance strain gauge to launch the experiment.Secondly, it's put forward a new way of strain brick creating and installing under the base of predecessors. The advantage of this way reduce the difficulties of experiment, and it cut down the influence of explosion stress wave spreading because of the cement mortar test block layered.Thirdly, the signal of numerical value is positive when the resistance strain gauge is subjected to tension; the signal of numerical value is negative when the resistance strain gauge is under pressure.Fourthly, the voltage, strain, and strain rate of testing point decrease along with the bigger distance from explosive source, moreover, the rate of change decrease.Secondly, the testing point has a large numerical value on voltage, strain, and strain rate which closed to the center of explosion.Fifthly, the strain rate decreased with the increasing of distance from blasting center. It explain that the testing point the further distance form blasting center,the harder to be destroy.Sixth, the stress wave roughly similar which blocks have same diameter; the stress wave in rock has a better accordance degree with theoretical which cement mortar test block has a bigger diameter.