Interlaid rock is an important component in the construction of neighborhood tunnels that supports and reinforces the area between two tunnels. However, the blasting load during excavation can sometimes damage the interlaid rock and threaten the stability of a tunnel’s structure. This paper presents a case study of the small clearance section of the Liantang highway tunnel project in Shenzhen, China, where the minimum distance between the two tunnels involved is only 0.5 m. To reduce the damage to the interlaid rock caused by blasting loads, we proposed a four-part excavation method with a vibrationcushioning rock layer in the following tunnel of neighborhood tunnels. Numerical simulation was used to model the damage prevention mechanism of the vibration-cushioning rock layer and to better understand the propagation of cracks in the interlaid rock. Furthermore, based on the simulation results, combined microseismic controlled-blasting technology was implemented, using innovative blasting patterns combined with different charge structures and blasting equipment designed according to the varying thickness of the interlaid rock. Finally, this implementation succeeded in protecting interlaid rock during blasting operations.

supportedbytheNationalNaturalScienceFoundationofChina(No.51934001)；

1. Introduction
2. Overview of the Liantang tunnel project background
3. Tunnelling method for the following tunnel
3.1. Excavation partition scheme design
3.2. Preliminary blasting pattern in FT-Ⅱ
4. Interlaid rock damage mechanisms under cushioning layer blasting loads
4.1. A constitutive model and the basic mechanical parameters of rock materials
4.2. Calculation of single-hole blast load and its time history in tunnel blasting
4.2.1. Peak pressure of the detonation wave in an ideal state
4.2.2. Peak pressure of the detonation wave for uncoupled charge structures
4.2.3. Time history curve of the single-hole blasting load
4.3. Numerical model of FT-Ⅱblasting
4.4. Simulation results for blasting damage in interlaid rock
5. Controlled blasting design for the following tunnel
5.1. The CMCB technology
5.2. Blasting deigns for FT-Ⅱusing the CMCB technology
5.3. Numerical simulation of the interlaid rock damage caused by the CMCB technology
5.4. Monitoring of blast induced vibration and blasting effects
6. Discussion and conclusions

Xiaodong Wu,Min Gong,Haojun Wu,Guangfeng Hu,Sijie Wang.Vibration reduction technology and the mechanisms of surrounding rock damage from blasting in neighborhood tunnels with small clearance[J].International Journal of Mining Science and Technology,2023,33(05):625-637.