Abstract: To investigate and determine the effect of excavation blasting on the characters of the weak intercalation in the layered rock slope is the prerequisite for correctly carrying out the slope stability analysis and its retaining structure design The authors, in combination with the site short-hole lamination blasting test,  investigated the change in the weak intercalation characters during short-hole blasting by LS-DYNA3D simulation, discussed the displacement distribution, compactness and change law of the weak intercalation at positions with different distances away from the blasting source, and deduced the critical displacement value (0.1mm) leading to the lamination breakage by blasting and the approximate calculation formula for the compactness.Furthermore, based on the simulation of the lamination breakage effect of long-hole blasting under the same geological conditions, the difference between and causes of long-hole and short-hole blasting in the effects on weak intercalation characters were analyzed.The investigation results show that short-hole blasting forms near-round blasting cavities with about 28.7cm radius that are slightly projecting in upper, lower, left and right directions, while in the case of long-hole blasting, the near-round blasting cavity behind the charge has a radius (89.1cm) that is far smaller than that ( 138.7 cm) of the cavities in the other three directions and the upper and lower surfaces of the weak intercalation strongly backward curves.With the increase of the distance to the blasting source, the displacement of the weak intercalation is gradually decreased and when the distance is smaller than 40 cm in short-hole blasting and 100 cm in long-hole blasting, the displacement decreases very rapidly with the decrease of the distance.The compactness of weak intercalation is high near the blasting source and decreases rapidly and with the distance increase, the compactness decreases gradually.

Key words: Layered slope, Bench blasting, Numerical simulation, Characters of weak intercalation