A case study is
conducted on the entrance section of a highspeed railway tunnel blasting
project to address the challenges expected during excavation by rock blasting,
and multiple groups of hydrostatic and nonhydrostatic
stress loading conditions are set up to numerically simulate the wedge cutting
blasting process and analyze the influence of different ground stress
conditions on the expansion of rockburst cracks. The rationality of the model
parameters is validated by comparison with the measured data. The results reveal
that: (1) The compressive stress component of the stress wave superposition
area is higher because the section being cut is inclined to the free surface,
resulting in greater compressive damage to the rock inside the holes. At the
same time, cracks are generated at a distance from the hole, and part of the
rock between the blast holes that is near the free surface suffers tensile
damage, which is conducive to the blasting of the subsequent auxiliary holes.
(2) Under hydrostatic stress conditions, the evolution of rock blasting damage
is inhibited with an increase in ground stress, while under nonhydrostatic ground stress conditions, the extent of the damaged
region expands along the direction of the maximum principal stress, and the
difference between the lengths of the horizontal and vertical crack of the
groove cavity becomes more pronounced with a decrease in the lateral pressure
coefficient. (3) When the hydrostatic stress is around 20 MPa and the wedge cut
angle is about 60°, the effect of rock blasting is less
affected by the ground stress.
