A method of inverted T cut blasting for super-large cross-section tunnel excavation was put forward.Besides, the formation mechanism of blasting cavity and were studied.Based on the engineering background of Longnan tunnel, the blasting effect of on-site single wedge and inverted T cut blasting are comparative analyzed by numerical simulation.Finally, the blasting effect of the inverted T cut blasting was verified by the field experiments.Results show that the maximum damage zone occurs at the location 1/4 blasthole length from the blasthole bottom and the location is mostly affected by cut blasting.The volume of the blasting cavity formed by the inverted T cut blasting is larger than that by the single wedge cut blasting.And the effective stress under the inverted T cut blasting is four times as large as that under the single wedge cut blasting at the same location except for the free surface.At the location near the free surface, the effective stress under two cut blasting methods is basically same.When the inverted T cut blasting is used for the tunnel blasting excavation, an average utility of 90.2% of the blasting holes can be reached, the specific charge reduces from 0.78 kg/m3 to 0.75 kg/m3 and the smooth blasting effect is improved obviously, which speed up the construction progress and save the construction cost. © 2020, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.
