Analysis of the influence of lately excavated tunnel blasting on the vibration of early excavated tunnel in small-space tunnel

Abstract

In order to study the impact of the blasting construction of lately excavated tunnel of the large-section tunnel with small spacing on the early excavated tunnel, the propagation law of vibration velocity of initial support of early excavated tunnel under blasting load is analyzed by combining field test and numerical simulation based on the Mongol Road Tunnel of the Zamalong-Daotanghe Highway Reconstruction and Expansion Project in Qinghai Province; The results show that the radial vibration velocity in the initial support of early excavated tunnel is obviously greater than the vertical vibration velocity and tangential vibration velocity in the blasting construction of lately excavated tunnel with large section and small spacing. The radial vibration velocity of the blasting side of the tunnel is obviously greater than that of the back side, and the maximum is found at the arch waist of the blasting side. The peak value of the radial vibration velocity of the initial support of early excavated tunnel is the maximum at the same section position as the blasting excavation face, and gradually decreases with the increase of the blasting center distance. Compared with the vibration velocity of the initial support before and after the excavation face, the peak attenuation rate of the vibration velocity in front of the blasting excavation face is slightly less than that behind the excavation face.