|
|
Strain energy characteristics of surrounding rock under blasting load and transient release of geostress during excavation of circular tunnel |
FAN Yong1,JIANG Lu1,LU Wenbo2,ZHOU Yihong1,ZHAO Chunju1,YAN Peng2 |
(1. College of Hydraulic and Environmental Engineering,China Three Gorges University,Yichang,Hubei 443002,China;
2. State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan,Hubei 430072,China)
|
|
|
Abstract During the excavation of deep tunnel in rock mass,the energy release and dissipation are the important factors which lead to the damage of surrounding rock. The blasting excavation of deep circular tunnel was studied theoretically to investigate the variation of strain energy in surrounding rock under the blasting load with multi-micro-second delays,the repeated disturbance of transient release of geostress,and the coupling effect of these two dynamic loads. The damage range was calculated based on the elastic strain energy criterion. Results show that the strain energy in surrounding rock under the blasting load increases firstly,then decreases and stabilizes finally. The strain energy under the transient release of geostress decreases firstly,then increases and stabilizes finally. The dynamic adjustment of strain energy is greatly influenced by the coupled effect of blasting and geostress release. This effect is reflected most obviously in the two rings of stope holes and a ring holes near the excavation boundary. The blasting load causes mainly the tensile failure of the surrounding rock,while the transient release of geostress results mainly in the compression-shear failure. The existence of the geostress restrains the damage caused by blasting and reduces the damage range of surrounding rock. At last,the correctness of the theoretical method is verified by the measured damage range of diversion tunnels in Jinping II hydropower project.
|
|
|
|
|
[5] |
COOK N G W,HOEK E,PRETORIUS J P G,et al. Rock mechanics applied to the study of rockbursts[J]. Journal of the South African Institute of Mining and Metallurgy,1966,66(10):436-528.
Your browse does not support frame! | | | |