Experimental Study On Attenuation Law Of Blasting Stress Wave In Columnar Charge Of Jointed Rock Mass

The blasting technology used in the construction of subway in Guiyang City is used as the engineering background to study the attenuation law of blasting stress wave in jointed rock mass.By studying wave theory,similarity theory and dimensional analysis theory,this paper determines the similarity criterion of karst geomorphic jointed rock mass,and then based on model test,and finds suitable similar model materials according to similar criteria,and makes5 different ratios.A similar model of cement mortar,in the process of making the model,the pore structure in the original rock is simulated by placing uneven ice cubes in the cement mortar,and then the static test is carried out on the different proportions of the cement mortar samples and the original rock test.From the results of the mechanical test,the appropriate cement mortar ratio is cement:sand:water=1:2:0.4.The blasting sample is prepared on the basis of the ratio,and the placement method of the strain brick is optimized to reduce the interference of the operating factors on the test.The super-dynamic strain gauge is used to test the blasting stress wave,and the relationship between the stress peak value and the blasting distance of the test data is analyzed,and the propagation law of the blasting stress wave in the radial direction of the blasthole under the coupled charge is better studied.Blasting vibration,the attenuation index?and the field coefficient k in the Sadowski formula are corrected.The main findings are as follows:?1?The similarity criterion of jointed rock mass with karst geomorphology is studied,and a similar model is made according to the similarity criterion.?2?After the columnar drug pack is exploded in the center of the cement mortar test block,the peak value of the stress wave decreases with the distance source,and the closer to the source,the faster the stress peak decays;?3?The stress wave data of different distances of the model under the explosive charge of the cylindrical drug pack are fitted and analyzed.The propagation attenuation characteristics of the blasting stress wave in the radial direction of the blasthole are obtained.The peak value of the stress wave and the linearity of the explosion source are different.Relationship:?r=4836.30712?R₀/R?^1.63.