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Study on the Movement Law of Rock Blocks inside the Cavity in Wedge Cut Blasting
(1. Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350116; 2. Institute of Explosion Technology, Fuzhou University,Fuzhou 350116; 3. Fujian Province Traffic Academy Co., Ltd., Fuzhou 350004)
Abstract To study the movement law of rock blocks inside the wedge cut cavity in tunnel blasting and to determine the reasonable delay time for wedge cutting, a theoretical model of the rock block throwing process in wedge cut blasting was established based on reasonable assumptions. The time-history curves of rock block movement inside the wedge cut cavity under different design parameters were solved using the one-dimensional unsteady flow law and Newton's second law. The SPH-FEM coupled numerical simulation was used to verify the rationality of the derived movement law of rock blocks inside the cavity and the throwing process of the rock blocks to be blasted under different hole network parameters, as well as the throwing characteristics and movement law of rock blocks in the cavity. The results indicate that when the first wedge cut depth is 2.0 meters, the reasonable delay time for the second wedge cut hole in soft rocks, medium-hard rocks, and hard rocks is 32.68-35.66 ms, 33.10-36.45 ms, and 34.4-38.22 ms, respectively. The designed delay time for the "two-step" wedge cutting needs to be greater than the above-mentioned cavity formation time.
Abstract：
To study the movement law of rock blocks inside the wedge cut cavity in tunnel blasting and to determine the reasonable delay time for wedge cutting, a theoretical model of the rock block throwing process in wedge cut blasting was established based on reasonable assumptions. The time-history curves of rock block movement inside the wedge cut cavity under different design parameters were solved using the one-dimensional unsteady flow law and Newton's second law. The SPH-FEM coupled numerical simulation was used to verify the rationality of the derived movement law of rock blocks inside the cavity and the throwing process of the rock blocks to be blasted under different hole network parameters, as well as the throwing characteristics and movement law of rock blocks in the cavity. The results indicate that when the first wedge cut depth is 2.0 meters, the reasonable delay time for the second wedge cut hole in soft rocks, medium-hard rocks, and hard rocks is 32.68-35.66 ms, 33.10-36.45 ms, and 34.4-38.22 ms, respectively. The designed delay time for the "two-step" wedge cutting needs to be greater than the above-mentioned cavity formation time.
WU Guobin1,
2 CHEN Bigang3 CHEN Zhihuo3 LIAO Dagang3 LOU Xiaoming1,
2 ZENG Huaheng1 etc
.Study on the Movement Law of Rock Blocks inside the Cavity in Wedge Cut Blasting[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(6): 21-28
2024, Vol. 61 