Characteristics of strain rate and strain energy during blasting unloading of high stress rock mass

CHEN Yang; WU Liang; CHEN Ming; XIANG Xiaorui; YANG Deming

doi:10.11883/bzycj-2018-0225

Volume 39 Issue 10

Oct. 2019

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CHEN Yang, WU Liang, CHEN Ming, XIANG Xiaorui, YANG Deming. Characteristics of strain rate and strain energy during blasting unloading of high stress rock mass[J]. Explosion And Shock Waves, 2019, 39(10): 103202. doi: 10.11883/bzycj-2018-0225

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CHEN Yang, WU Liang, CHEN Ming, XIANG Xiaorui, YANG Deming. Characteristics of strain rate and strain energy during blasting unloading of high stress rock mass[J]. Explosion And Shock Waves, 2019, 39(10): 103202. doi: 10.11883/bzycj-2018-0225

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Characteristics of strain rate and strain energy during blasting unloading of high stress rock mass

doi: 10.11883/bzycj-2018-0225

CHEN Yang^{1, 2
,},
WU Liang^{1, 2
,
,},
CHEN Ming³,
XIANG Xiaorui^{1, 2},
YANG Deming^{1, 2}

1.
Department of Engineering Mechanics, School of Science, Wuhan University of Science and Technology, Wuhan 430065, Hubei, China
2.
Blasting Technology Research Center, CRPCE-WUST, Wuhan 430065, Hubei, China
3.
State Key Laboratory of Water Resource and Hydropower Engineering Science, Wuhan University, Wuhan 430072, Hubei, China

Received Date: 2018-06-21
Rev Recd Date: 2019-06-11

Available Online: 2019-09-25

Publish Date: 2019-10-01

Abstract

Abstract

To explore the unloading of blasting excavation in highly-stressed rock masses for hydropower stations, an axial loading and unloading test platform was independently developed. The dynamic strain and strain rate data of rock bars during the blasting process were experimentally obtained. The measured data indicate that the strain rates in the rock bars are all above 10⁻¹ s⁻¹ during the blasting loading and unloading and the initial stress unloading near the excavation face. It is verified that the unloading of blasting excavation in the highly-stressed rock mass is a dynamic process. A one-dimensional mechanical model for the initial stress unloading was established, and the propagation mechanism of the unloading wave was revealed. By analyzing the temporal and spatial distribution characteristics of the strain energy density in the blasting unloading process, the relationship between the strain energy density and the strain rate rule in various stages of blasting was established. Based on the measured data, the implicit-explicit sequential solution method was applied to further analyze the variation of strain rate along the rock bar in different stages of the loading and unloading in deep rock mass. The results show that the average strain rate and the decay rate decrease gradually in the loading stage of the blasting. And the average strain rate in the unloading stage of the blasting decreases along the bar, while the strain energy induced by the initial stress can release steadily, and the corresponding average strain rate has no attenuation trend.
- rock mass,
- strain rate,
- strain energy,
- ground stress,
- dynamic unloading

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References(20)

References

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