# Numerical Simulation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality: A Case Study
###### Abstract
[17] adopted self-made uniform similarity materials and digital image correlation methods and found that with the increase in buried depth, the ground stress exhibited a significant effect on smooth blasting, and the fracture surface tended to be flat with the increase in in situ stress. [PERSON] et al. [18] used the finite element numerical simulation software ANSYS/LS-DYNA to simulate the blasting process of the coupled charge in the peripheral holes in smooth blasting. The results showed that when the peripheral hole spacing was 0.6 m, the surrounding rock stress and spalling were the smallest, which could improve the efficiency of smooth blasting. Besides the studies in field tests, laboratory tests and numerical simulation on the quality improvement of smooth blasting, over- and under-excavation prediction model, random model, and comprehensive optimization control model were used to select the best blasting scheme. Taking the smooth blasting of Koyna Lake Tap Tunnel in India as an example, [PERSON] et al. [19] compared the prediction model calculated by the peak particle velocity (PPV) of blasting particles with the measured overbreak and underbreak. They proposed the overbreak and underbreak BIRD prediction model and calculated the crack development state and the PPV threshold of overbreak and underbreak. Thereafter, [PERSON] and [PERSON] et al. [20] adopted the BIRD prediction method on the basis of the measured data of the tunnel to control the overbreak and underbreak errors of the four tunnels within 10%, thus verifying the feasibility of the BIRD overbreak and underbreak prediction model. [PERSON] et al. [21] proposed a prediction model of overbreak and underbreak on the basis of fuzzy set theory, which controlled overbreak and underbreak by adjusting the four parameters of blockage length, hole depth, charge amount, and hole spacing. [PERSON] et al. [22] established a Monte Carlo stochastic model on the basis of controllable parameter adjustment to predict overbreak and underbreak. [PERSON] [23] et al. proposed the constructing method of tunnel smooth blasting quality control index system and established the smooth blasting quality control index system with levels of geological conditions, explosive properties, borehole parameters, charging parameters, initiation method, tunnel parameters, and construction factors as indices. The predecessors mainly considered the physical and mechanical properties of rock mass, explosive properties, charging parameters, and construction methods in researching the quality of tunnel smooth blasting. However, the influence of the types of rock mass structure on tunnel overbreak and underbreak is not fully considered. Besides, the current research on the influence of rock mass structure on the overbreak and underbreak of tunnel smooth blasting is mostly focused on a single rock mass structure; it rarely involves different rock mass structures. Therefore, on the basis of field tests, this paper adopted the method of orthogonal numerical tests to study the influence of the rock mass structures, such as massive integrity structure, massive structure, layered structure, and cataclastic structure, on the quality of tunnel smooth blasting.