Optimization Research Of Hole Network Parameters In Underwater Drilling Blasting

In recent years, the exploitation of marine resources in our country is increasing,the underwater drilling blasting technology has been used widely in the underwater reefblasting engineering, but the complexity of underwater environment makes underwaterdrilling blasting more complex than land drilling blasting. The optimization research ofhole network parameters in underwater drilling blasting has great significance to makethe blasting construction design and save the economic cost.The paper is based on reef blasting in Xiamen port second phase project, startingfrom the study of underwater drilling blasting rock breaking mechanism, discusses themain influencing factor of the underwater drilling blasting, combining the blastingoptimization model, the numerical simulation technology and field experiment toresearch the optimization of underwater drilling blasting engineering networkparameters, obtains the following conclusions:Firstly, comprehensively analysize the rock breaking mechanism and thecharacteristics of underwater drilling blasting, and concludes the underwater drillingblasting rock breaking mechanism, at the same time, analyzes the main influencingfactors of the underwater drilling blasting，such as water depth, rock mass structure androck mass property.Secondly, the network parameters optimization model is proposed based on theclassic Zhong Hanrong model, according to the statistical data, using the mathematicalstatistics method and the equation of the broken blocks, obtaines the specific functionexpression of this project optimization model, and in the case of constraint function andconstraint conditions, concludes the optimal blasting hole net parameters.Thirdly, using ANSYS/LS_DYNA dynamic finite element analysis software set upeight kinds underwater drilling blasting models with different hole spacing, row spacingand the block length, analysizing the stress nephogram and the stress time history curveof the same model with the middle or bottom of hole detonation initiation, finds therock burst produced by blasting loads mainly depends on the tangential tensile stress,and the latter can produce the uniform stress field, this is beneficial to decrease the rateof large rock. Finally, On the basis of the small hole net parameter model, by comparing themodel of rock unit tangential tensile stress, can conclude that the blasting model withthe optimal hole network parameters which can achieve the broken target and save thecost.The results showed that the optimal network parameters of the xiamen port secondphase reef blasting engineering is that the hole spacing is2.5m, the row spacing is2.2m, the near coefficient is1.130, the block length is1.5m, specific charge is1.75kg/m3.Using the optimized parameters for the construction, the large rate is reduced by30%on average, the shallow point rate is dropped to2%, greatly shorten the constructionperiod and reduce the construction cost, it can provide a reference for similarunderwater drilling blasting projects.