In order to forecast and control the damage zone of surrounding rock under blasting load

sound wave tests have been conducted in the construction site of Meihuashan Tunnel in Jiangxi province dragon railway. Based on the change rate of sound wave speed

damage zone size of surrounding rock are obtained. On this basis

a statistics-based damage variable of rockmass has been proposed based on micromechanics. Damage zone size of surrounding rock under blasting load at different in-situ stresses is thus studied by using three-dimensional finite difference software. Calculations show that the numerical simulation results agree well with the site monitoring results. With the in-situ stress increasing

the size of damage zone decreases first

then increases

and increases by a large margin; when the in-situ stress is high

local parts such as tunnel roof

floor damage is more obvious; it is shown that the in-situ stress has significant impact on surrounding rock damage distribution. With the lateral pressure coefficient increasing

the size of damage zone decreases first

then increases

but the growth rate decreases. The results provide foundation for stability analysis of tunnels under high in-situ stress and supporting design of the cracked surrounding rock.