The Application Research On The Excavation Of Smooth Blasting In Pile Holes

At present the excavation smooth blasting parameters of pile holes mainly rely on engineering analogy, different designers design different blasting parameters because of grasping different blasting theories and experiences and the blasting quality are uneven. Therefore, this thesis is based on related theories about blasting mechanism of seam, fracture mechanics and elastic mechanics to deduce the calculation formula of perimeter blastholes in smooth blasting including the dynamite density and uncoupling factor. At the same time, using BP neural network establish blasting parameters optimization model of pile holes excavation to optimize some smooth blasting excavation parameters of pile holes including design penetration, specific explosive, optical thin film thickness, tao slot pitch, auxiliary distributed spacing and perimeter blastholes spacing. This method not only provide theoretical basis for the parameters design of excavation blasting, but also can use existing empirical data of excavation smooth blasting and the engineering geological conditions, in the meanwhile, using the genetic algorithm GA to optimize the BP network connection weight and threshold value can make up the defects of BP network in order to get a more optimal blasting parameters. Practice shows that the relative error of GA-BP is smaller than BP neural network.Using the calculation formula of dynamite density and uncoupling factor and GA-BP network to design the excavation smooth blasting parameters of slope anti-slide pile hole (UB11) 3.0×2.0 and tower footing pile holes in dadu river bridge on yaan shore, then these parameters were used to excavation blasting experiment in field, supplemented by blasting vibration monitor in real time, the vibration of measuring points in numerical simulation as well as before and after the sound detection of excavation blasting. The results show that the vibration peak of two measuring points in numerical simulation were coincident with the blasting vibration monitoring results and the vibration velocity of measuring point 1 was only 9.71 cm/s, less than the minimum value of the safety procedure 10cm/s; The vibration velocity of measuring point 2 in the first blasting test only reaches 5.79 cm/s, fully satisfied with the safety vibration vibration of slope surface; Before and after the excavation blasting tests of acoustic contrast, results show that the average rate of 8 sound wave measuring points in pile hole excavation blasting arrived at 5.7%, less than 10% of quantitative standard stipulated in the codes, the field test of excavation smooth blasting in anti-slide pile holes and tower footing pile holes. Therefore, in this thesis a combination of theoretical derivation and GA-BP neural network optimization design method of smooth blasting parameters in pile holes excavation can provide reference for similar engineering excavation smooth blasting parameters design.