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A Simulation Study of Controlled Coyote Blast with Column and Strip-shaped Charge and Its Application in Highway Subgrade

Author: LiJianHua
Tutor: ChenShouRu
School: Central South University
Course: Mining engineering
Keywords: column and strip-shaped charge coyote blasting displacement Field stress Field subgrade
CLC: U416.1
Type: PhD thesis
Year: 2005
Downloads: 725
Quote: 2
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Since the 1980s, conspicuous achievements have been gained in the construction of the infrastructure, such as highways and high-speed railways, thus they effectively promoted the development of the economy and society in our country. Especially in the recent three years, such infrastructure has exhibited its infinite vitalityUndoubtedly, numerous problems concerning the rock blasting of the subgrade will arise in the process of the construct of the highways and high-speed railways. A lot of researches have been done on the coyote blasting with the column and strip-shaped charge by the scholars from home and abroad. However, no substantial breakthrough has been gained in the studies of the experiment and theory of the coyote blasting with the column and strip-shaped charge due to the defects of experimental methods and mathematical models. Therefore, the application and spread of the coyote blasting with the column and strip-shaped charge have been limited.Based on the practice of the blasting of the subgrade in the highways and high-speed railways, this paper is entitled as "A simulation study on the controlled coyote blasting with the column and strip-shaped charge and its application in the subgrade of the highway and high-speed railway". It has devoted itself to the controlled coyote blasting with the column and strip-shaped charge by adopting the laser technology including dynamic holophotoelasticity and holographic interference method, meanwhile, the ANSYS-DYNA software is applied for the analysis of the computer numerical simulation. The main outcomes are as follows:1) On the basis of the existing studies, the formula Q = e·K·f(n)·W~3·η for the controlled coyote blasting with the column and strip-shaped charge in subgrade has been established, indicating that Q is linear with η on the condition that the basic parameters like e,K, n, W are fixed.2) An experimental system of blast model of three-dimensional dynamic astigmatic photo-elasticity has been established by using the ruby pulse laser apparatus. By detonated the column and the strip-shaped charge at one end, two ends and mid-point, four dynamic stress fringe patterns of the three group models at four separate moments have been got. Comprehensively considering of intensity and homogeneity of the total stress field, the blasting effect when the column and strip-shapedcharge was detonated simultaneously at two ends is the best of all; at mid-point takes the second place, then at one end.3) A laser experiment adopting holographic interference method has been made on the equal proportion model of the blasting of subgrde, and three sets of dynamic displacement fringe patterns in a group model have been drawn, the conclusion from the analysis of the displacement field shows that the extremum displacement on the perpendicular bisector of the column and strip-shaped charge, and the maximum value of the displacement field, are three times more than the values on other section, as well as the average isosurface displacement.4) By applying ANSYS-DYNA2D program, a numerical simulation study had been made on the condition that the column and strip-shaped charge is detonated at one end, two ends and mid-point respectively with three different exploding speeds, i.e. low speed ( v = 800 m/s ) , mid-speed (v = 3600 m/s) and high-speed (v = 6100 m/s ) . The rule for the stress field as well as the displacement field of the column and strip-shaped charge at different speed and in different detonating points has been gained accordingly, meanwhile, the effect of blasting detonated simultaneously at two ends with mid-speed is the best.By using ANSYS-DYNA3D program, a three-dimensional numerical simulation research has been done for the equal proportion model of the road-cutting slope of highway with the controlled blasting for the column and strip-shaped charge. The rule for stress field as well as the displacement field of the column and strip-shaped charge detonated at two ends under various ratio of length to burden has been obtained. Meanwhile, the ratio of length to burden as 0.9-1.25 is the best.Considering much of the effect of blasting vibration of the column and strip-shaped charge on superior isosurface displacement, using the mid-speed explosive and adopting the way to detonate simultaneously at two ends, the outcomes of the research have been applied in the blasting of the subgrade of one highway The blasting negative effects such as shake and slungshot have been effectively controlled, and the blocks are well-proportioned. A breakthrough has been made for the limitation of massive explosion applied in the subgrade construct criterion. The project was accomplished half a year ahead of the schedule, with the profit up to 5 million Yuan (RMB). During the three years after the road was open to traffic, no damage of the subgrade and slope has been find yet, and proved the feasibility of the theoretical analysis, model experiment and numerical simulation in the research

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CLC: > Transportation > Road transport > Road works > Roadbed, pavement engineering > Subgrade
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