Current initiation delay settings in high-gas tunnels typically follow fixed intervals (0 ms, 25 ms, 50 ms, 75 ms, and 100 ms), yet the limited number of delay segments (fewer than the blast hole rows) forces auxiliary holes to share delays. This configuration, combined with inadequate cut-hole delay durations, significantly compromises optimal blasting outcomes. To address this issue, a field-programmable digital electronic detonator was implemented. Theoretical analysis determined the complete rock mass fracturing duration in the cutting area to be 40 ms, which was further validated through numerical simulation of rock mass displacement dynamics, establishing this as the optimal delay interval. The study reveals that rock mass displacement in the cutting area progresses through three distinct phases: fracture propagation, volumetric expansion, and rock material ejection. Based on the optimal cutting area delay time, the ideal initiation sequence for blast hole rows was established as 0 ms, 40 ms, 60 ms, 80 ms, 100 ms, and 120 ms, with subsequent field validation conducted in a high-altitude gas tunnel. Statistical analysis of blasting performance demonstrates that implementing the optimized delay sequence (0 ms, 40 ms, 60 ms, 80 ms, 100 ms, and 120 ms) achieves over 90% half-hole preservation and controls linear overbreak within 20 cm, satisfying construction specifications while validating the delay configuration′s efficacy, with direct applicability to analogous tunnel blasting operations.

The Jiangshuiquan Road Station tunnel construction along Jinan Metro Line 4 is located in a highly urbanized area with building proximity constraints, featuring a critical minimum clearance of 3.58 m between the underground excavation zone and adjacent pier foundations. This study consequently established a controlled test section within the subway tunnel project, characterized by lower blasting risk potential, to conduct systematic comparative analyses of three distinct blast initiation network configurations: S-patterned, co-directional, and bilateral-oriented vaults. Under controlled blasting conditions with 50 ms inter-row and 5ms inter-hole, comprehensive monitoring of pavement vibration velocities and waveform characteristics was carried out to evaluate vibration differentials across distinct initiation networks systematically. Concurrent quantitative analysis of rock fragmentation effects revealed that, while maintaining identical blasting parameters, the S-patterned detonation network generated the highest peak particle velocity of 0.87 cm/s, followed by co-directional detonation (0.55 cm/s), with the lowest on both sides (0.41 cm/s). Comparative analysis reveals that co-directional detonation achieves a 37% reduction in peak vibration velocity compared to S-patterned detonation. In comparison, the bilateral crown-oriented detonation demonstrates optimal vibration attenuation, achieving approximately 52% peak reduction. Post-blast fragmentation analysis further indicates that the bilateral-to-center detonation method yields the lowest oversized fragment rate (< 25%) and concurrently the highest fine particle proportion, thereby exhibiting superior overall fragmentation quality. Finally, the bilateral crown-oriented detonation network was implemented in the highest-risk blasting zone adjacent to pier foundations to validate these findings. This study establishes a methodological framework for optimizing initiation networks and controlling blast-induced vibrations in urban subway tunnel construction within a complex environment.

This study employed field tests, numerical simulations, and engineering application methods to investigate the influence of the law of aluminum pharmaceutical-shaped jets with varying cone angles and wall thicknesses during penetration of a concrete target plate at a blasting height of 6D. The structural parameters responsible for producing favorable penetration effects were identified and subsequently implemented to improve the detonation efficiency of the shaped energy spacer charge in practical engineering applications. The results demonstrate that in the field test, the size of the funnel pit initially increases and subsequently decreases as the cone angle varies from 60° to 120°, with the maximum diameter (48.88 mm) and depth (23.54 m) of the funnel pit occurring at a cone angle of 110° and a wall thickness of 2 mm. The numerical simulation and test results align with the variation patterns of funnel pit diameter and depth, exhibiting minimal error, thereby validating the effectiveness and accuracy of the penetration test. The optimized structural parameters of the cover were implemented in the 1# transverse hole of a tunnel, and ten field test cycles confirmed successful detonation without explosion rejection, ensuring operational continuity and blasting safety. These findings offer a reference for tunnel blasting and related engineering applications.

Field tests in a region of the plateau were carried out to study the “poly device+emulsion explosives” in tunnel surface blasting and to achieve the feasibility of peripheral hole air spacing charge and poly device on the explosives detonation distance. A seamless steel tube was used to simulate the tunnel peripheral hole for two or more sections of “emulsion explosives+poly device” detonation. A martyrdom test was implemented with # 2 rock emulsion explosives. The maximum stable detonation and martyrdom distance were obtained through several groups of experiments. The test results show that the maximum stable detonation and martyrdom distance 15 cm length of polymerized explosives and # 2 rock emulsion explosives are respectively 230 cm and 115 cm in the seamless steel tube. The maximum stable detonation distance of multi-section polymerized explosives can reach 80 cm. Due to the radial constraints on the detonation wave of the polymerization device, the front end of the conical metal drug mask explosion formed by the polymerization of energy jets significantly increases the axial and upward shockwave energy, which makes it possible to increase the energy of the shockwave. The emulsion explosives in seamless steel pipe detonation distance increased significantly upward shock wave energy, which can be applied to the tunnel perimeter hole, replacing the detonating cord to achieve air spacing charge and enhance the effect of surface blasting, cost savings, and time savings.

Smooth blasting in tunnel construction needs decked charge in the peripheral holes. However, this charging method has certain limitations and risk of misfire due to the usage of detonating cord together with detonator. So, it is an urgent problem to improve the effect of smooth blasting and ensure tunnel excavation efficiency at the same time. Related research was conducted by field tests, and a new initiation technology of “Shaped device+digital electronic detonator” has been proposed, which was applied to a plateau tunnel. The experimental results show that, compared with the original technology, the powder factor by using the new technology has been reduced by 0.2 kg/m³, the half-hole rate is increased by 5%, and the average charge time is reduced from the original 1.3 h to 1.0 h. The tunnel excavation cycle footage is stabilized, and the cost of consumables is greatly reduced, and it is expected to be widely used in tunnel smooth blasting.