| When the water inlet of a hydraulic tunnel is located tens or even hundreds of meters underwater,the application of underwater rock plug blasting technology is usually the best choice to achieve the water inlet penetration.With the advantages of easy vibration control and good penetration effect,rock plug full-row hole blasting method has become a development trend of rock plug blasting.Due to the differences in topography and hydrology,each rock plug blasting project is unique,and the blasting design usually relies on the experience of the technical staff,which makes it difficult to ensure the successful penetration of the inlet.Therefore,it is necessary to conduct rock plug blasting penetration test before formal blasting to test the rationality of blasting design and optimize the blasting design parameters according to the test results.However,there are differences in water pressure,water environment,dip angle and diameter between the test rock plug and the actual rock plug,which may make it difficult for the test penetration results to accurately reflect the actual penetration results.Therefore,the scientific nature of the tunnel test method needs to be studied;meanwhile,the optimization study of the full-row rock plug blasting design is carried out,and the parameter optimization method is proposed to provide reference for similar rock plug blasting projects.This paper combines a rock plug blasting project,using theoretical analysis,numerical simulation and field tests and other research methods,the main research work carried out and the results obtained include:(1)The penetration mechanism of rock plug blasting with full-drilling was analyzed;numerical simulation models of rock plug blasting with full-drilling were established using Hypermesh and LS_DYNA for various conditions with different lengths and rock strengths(characterized by elastic modulus),and it was concluded from the calculation results that:(1)The evaluation index of rock plug penetration effect tends to decrease nonlinearly with the increase of plug length and rock strength;(2)The peak tensile stress and damage degree of the rock body in the middle of the plug are obviously smaller than those in the two ends,and the key to penetration is whether the rock body in the middle can be blown out smoothly.(2)Numerical simulation models of different water pressure,water medium rock plug blasting were established,the calculation results show that within 100 m water pressure on penetration basically no effect,water medium on the rock plug pressure side of the rock fragmentation has an impact,need to increase the unit consumption of explosives(more than 1.7 times)to overcome;Numerical simulation models of different diameter rock plug blasting numerical simulation were established,the calculation results show that the smaller the diameter of the test rock plug,penetration test results are more difficult to reflect the actual;through the analysis of the location of the burst pile,qualitative study of the effect of rock plug inclination on the penetration effect,the results show that the existence of the inclination is conducive to penetration,regardless of the influence of inclination,directly using the tunnel level into the section to carry out penetration tests,horizontal rock plug penetration difficulty increases,can be used as the actual rock plug "penetration affluence factor".If the site conditions allow,the test rock plug with inclination angle can be constructed to get closer to the actual test results.(3)Based on the numerical simulation,a study was conducted to optimize the blasting parameters of full-row rock plug blasting,considering the effect of rock plug penetration and blasting vibration control to determine the reasonable range of explosive unit consumption;considering the superposition of blast stress wave vibration reduction to determine the optimal inter-hole delayed detonation time;considering the effect of rock plug penetration and the damage range of the shell hole to determine the reasonable range of inter-row delayed detonation time;based on a fullrow rock plug blasting project to optimize the reasonable range of explosive unit consumption is 1.17kg/m3<q<1.76kg/m3,the optimal inter-hole delayed detonation time is: ?tk=9ms,and the reasonable range of inter-row delayed detonation time is:50ms<?tp<200ms.(4)Based on the selected parameters,the tunnel method penetration test simulation was successfully carried out and applied to an actual rock plug blasting,which finally achieved a successful penetration of a rock plug,and the parameter optimization method can provide reference for similar projects. |
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