For large cross-section tunnel blasting, the rock mass in the middle of the tunnel face often experiences the phenomenon of “bulging” due to the unreasonable arrangement of the cutting holes. In order to eliminate the “bulge belly” phenomenon in large cross-section tunnel blasting, a new method of “wedge cut+high-energy hole” blast hole layout was proposed. Taking the Gonghe Village Tunnel of the Luqiao Expressway in Yunnan Province as the engineering background, a numerical model of “wedge-shaped cut+high-energy hole” was established using finite element software LS-DYNA. The effective stress at the bottom of the blast hole and dynamic damage of the rock mass were studied and compared with the on-site tunnel cut blasting plan. At the same time, the proposed new method was verified through on-site blasting experiments. The research results indicate that the “wedge cut+high-energy hole” blasting hole layout method can effectively eliminate the “bulge” phenomenon, reduce the number of cut holes and digital electronic detonators, and determine the rationality and applicability of this method. Besides, the stress values generated by measuring points 1, 2, and 3 at the bottom of the main cutting hole are relatively small. As the stress sharply rises to 454.9 MPa, the middle-retained rock mass can be effectively broken after the main cutting hole blasted with the high-energy hole explodes. Using the improved blasting method, the excavation efficiency increased by 16.9%, the average utilization rate of blast holes reached 91.5%, and the explosive consumption reduced by 19.7%. The proposed layout method of “wedge-shaped cutting+high-energy holes” for large cross-section tunnels can not only ensure construction safety, but also achieve the effect of reducing costs and improving construction efficiency.

The multi-body and discrete-body dynamic analysis of demolished reinforced concrete structures in China is based on the multi-body dynamic equation (symbol, function) and the variable mass collapse dynamic equation, and the comprehensive solution of the equation, including an analytical solution, is obtained. Using close-range photogrammetry and dynamic equation inversion, the plastic dynamic and structural dismantling parameters of damaged reinforced concrete materials are obtained. Based on the similarity criterion of dynamic equations solution, similarity criterion formulas of notch for different collapse modes of Various structures are established. Namely, the similarity criterion curve fitting formula (5), it's another formula (6), empirical formula (7) of single-notch for building toppling, the example modification curve C₄ of similarity criterion of inter-span falling, and the forward. Toppling similarity criterion formula (8) of backward-seated buildings with the single notch, the similarity criterion formula (9) of continuous impact collapse between floors of high-rise buildings, the empirical formula (10) of multi-notch in-situ impact collapse of high-rise buildings, the overturning similarity criterion curve of double-notch buildings in the same direction, and other notch-similarity criterion curve families of building structure collapse, etc. Furthermore, the building collapse rules of the demolition matching table of building structure-collapse mode-notch characteristics are put forward by analogy with 46 demolition examples from its notch similarity criterion curve and example diagram in China. The judgment rules of building collapse are determined when the coordinate points [λ (λ₁, λ_p), η_h (η_r)] of the building structure and the incision are near the top of the similarity criterion curve. The cut size of various demolition methods of different building structures can be easily determined, and dimensionless charts can determine the demolition effects. Therefore, a simple and accurate demolition control of blasting demolition can be realized using the multi-body dynamic incision control demolition technology (MBDC).

The blasting dynamic response of the gas pipeline and surrounding soil during the excavation of the cross passage at the entrance and exit C of Jinding Street Station of Beijing Metro Line 11 was analyzed using the finite software LS-DYNA. The numerical model's accuracy was confirmed by comparing it with blast-induced vibration data from on-site surveys. The study focused on the dynamic response of the buried gas pipeline to tunnel blasting, considering factors such as different cutting hole delay times, single hole charge, and soil properties. The results indicated that the peak particle velocity (PPV) from the numerical model was within 20% of the field test data. The PPV and peak effective stress (PES) of the pipeline were highest at the side back of the explosion source. A linear relationship between PPV values of the surface soil and the pipeline was observed when the horizontal distance from the tunnel center exceeded 3m in the axial direction of the gas pipeline. The PPVs and PESs on the cross-section of the gas pipeline did not change significantly with increasing delay times between cutting holes. Furthermore, increasing the charge of the cutting hole from 0.2 kg to 0.6 kg led to an increase of 0.5~2.5 times in PPVs and 0.5~1.5 times in PESs. The soil type around the gas pipeline also influenced the peak combined vibration velocity and effective stress, with silty clay having the greatest impact, followed by clayey silt, and then miscellaneous soil.

This study addresses the blasting demolition of an 18-story oval frame-core tube structure. Systematic analysis revealed that the structure's small height-width ratio and long span contribute to potential instability and collapse, with uneven stress distribution due to irregular shear wall placement within the core tube. To mitigate these challenges, delayed blasting and auxiliary weakening techniques were employed. The approach included pre-treatments such as splitting and cutting to transform the cylindrical structure into a wall-like form, reducing deviation during collapse. The building was divided into four blasting zones with increasing delay times, particularly extending the delay for the last two zones by 1 second to ensure sequential support point failure and prevent incomplete collapse. Additionally, the upper and lower double-incision folding blasting method was utilized to control vibration upon ground impact and enhance overall dissociation. The demolition process, lasting approximately 5 seconds, resulted in the building collapsing primarily along the designed direction with minimal backseat movement and evident structural failures. The sequential floor folding and concentrated pile blasting demonstrated effective demolition.

Drilling and blasting is still the most efficient way to explore deep phosphate mine excavation and mining. There is a severe constraint on the efficiency of phosphate mine digging as its level remained at 70 to 80 meters every month for many years. Therefore, the ore rock blastability classification is critical for the deep phosphate mine working face. The longitudinal wave velocity tests of the rock body in an underground phosphate mine in Yichang, Hubei Province, and measurements of physical and mechanical properties such as rock density, uniaxial compressive strength and tensile strength were carried out. The rock density, uniaxial compressive strength, tensile strength, and rock integrity coefficient were obtained for four types of rocks, namely, dolomitic striped phosphorite, dense striped phosphorite, argillaceous striped phosphorite, and carbon-bearing argillaceous dolomite. To complete the deep phosphorite workings of the mine rock blastability classification, a BP neural network model was established by stochastic functions to generate a large number of learning and testing samples using the Matlab neural network toolbox as taking the pre-measured rock density, uniaxial compressive strength, tensile strength and rock integrity coefficients as inputs and the rock blastability classification as outputs. The grading results show that dolomite-banded phosphorite and mud-banded phosphorite are moderately blastable, and dense-banded phosphorite and carbonaceous mud dolomite are difficult to blast. According to the classification results, the blasting parameters of the stope can be optimized to enhance the blasting effect, reduce the single consumption and the bulk rate of explosives, and improve the safety and economic benefits of deep phosphate mining.

As rock-breaking technology advances, the limitations of traditional explosive methods are increasingly evident. The liquid oxygen energy storage method, a new non-explosive technique, presents an uncertain blasting mechanism and scientific challenges that must be addressed. Field vibration tests were conducted to analyze the variation trends and the decay characteristics of peak vibration velocities in particles to further characterize the liquid oxygen energy storage rock-breaking blasts and address the challenges of applying empirical methods on-site. Additionally, indoor small-scale blasting experiments were performed to identify key parameters for small liquid oxygen charges. The experimental results reveal that the liquid oxygen energy storage effectively fractures rocks while maintaining low dust and noise levels. Peak particle vibration velocities at 3 m, 6 m, and 10 m under single blast conditions were 3.04, 1.24, and 0.62 cm/s, respectively. The small-scale charge tests reveal that for the liquid oxygen charge to detonate successfully and effectively fracture the rock, appropriate inflation time and pressure are required to prevent detonation and other issues. Increased inflation time and pressure lead to more significant adsorption of liquid oxygen by the charge's absorbent, facilitating saturation and enhancing detonation probability. Overall, the liquid oxygen energy storage method stands out due to its low vibration, environmental friendliness, and non-polluting nature, marking a significant potential advancement in engineering blasting.

Smooth blasting is generally used to control tunnel formation, which requires managing the density of the line charge. Conventionally, air-spaced axial uncoupled charges are used and connected by detonating cords. However, detonating cords require a large amount, are expensive and difficult to approve, and cannot achieve uniform dispersion of charges. Currently, bottom-concentrated charging structures are used without using detonating cords in the surrounding holes of tunnel excavation, leading to serious over-excavation and under-excavation. To address this issue, a new type of energy-gathering tube has been designed. This new tube combines a PVC half tube and energy-gathering cover with a fixed ring, enabling precise control of explosive amounts, simplifying the charging process, and ensuring the stability of the entire device. It is not limited by the water environment, providing efficient energy transmission and effectively controlling tunnel over-excavation and under-excavation. To evaluate the blasting effect of the new energy-gathering tube, it was first verified through a sacrificial explosion test. The test showed that with the new tube, multiple sections of the detonated explosive can be stably transmitted at 30 cm intervals with a dosage of 60 g. Numerical simulations also demonstrated the good cutting effect of the new tube. This new energy-gathering tube was applied in the Dongshan Tunnel of the Fenyang Shilou Expressway, achieving smooth blasting without detonating cords with a line charge density of 200 g/m and a half-hole trace rate of 90%, effectively reducing over-excavation and under-excavation.

A reasonable blasting construction method is critical to maintaining caverns' stability and water-sealing integrity. In this study, seismic wave detection and acoustic wave detection were conducted within a water-sealed cavern. The HHT signal analysis method was used to process the seismic wave signals generated by blasting, and both Empirical Mode Decomposition (EMD) and Ensemble Empirical Mode Decomposition (EEMD) were applied to compare and reduce signal mode aliasing, improving the accuracy of signal analysis. The marginal spectrum, instantaneous energy spectrum, three-dimensional energy spectrum, and loose zones in surrounding rock were used to evaluate the influence of different blasting schemes on the water-sealed caverns. The results show that the EEMD-Hilbert analysis method effectively mitigates mode aliasing issues caused by traditional EMD decomposition, producing a smoother and more reliable vibration velocity time-history curve. Marginal spectrum analysis of the reconstructed signal reveals that the frequency band of the double-sided wall heading method ranges from 200 to 380 Hz. In contrast, the frequency band of the single-sided wall guide pit method is narrower, concentrated between 110 and 250 Hz, with relatively lower frequency energy in both conditions. The combined instantaneous energy of the double-sided wall guide method is higher than that of the single-sided wall guide method, with 41.67% and 23.73% of the total instantaneous energy concentrated in the first section of the cutting hole for each method, respectively. The instantaneous energy distribution of the single-sided wall guide method is more uniform and lower than that of the double-sided. The range of loosening rings on both sides of the arch waist in the double-sided wall heading method is about 1.0 to 1.2 m. In contrast, the single-sided wall guide pit method measured 0.8 meters and 1.0 to 1.2 meters on the expanding excavation surface and guide tunnel surface, respectively. A joint analysis of the EEMD Hilbert method and acoustic detection indicates that the single-sided wall guide pit method is more suitable for blasting excavation in water-sealed caverns.

In constructing shield tunnels in a sea area, large-sized boulders and bedrock are often encountered, necessitating pretreatment via blasting. The effectiveness of blasting pretreatment is crucial for the regular excavation of shield machines. Based on Xiamen Metro Line 2 project, a refined blasting pretreatment method for boulders and bedrock in shield tunnels under the sea area is proposed. The method comprehensively considers overburden conditions, blasting fragmentation indexes, and marine biological safety standards. Specific steps include designing blasting parameters, calculating powder factor, determining single-hole charges and average block size, designing charge structures and initiation networks, predicting the distribution of blasting fragments, and optimizing the blasting program to minimize ecological impact. Field application results indicate that post-blasting fragment sizes are within 30 cm, meeting the size requirements for the shield machine. The shield machine could excavate smoothly through the blasting pretreatment section, with excavation parameters similar to those in regular sections. The proposed method achieved a refined, ecological, efficient and safe blasting construction in the sea section containing boulders and bedrock.

The impact of blasting vibration on surrounding buildings has been widely concerned. Based on the deep hole bench blasting project of Changtan Open-pit Coal Mine, the characteristics of the adjacent 11-story frame-shear structure office building are comprehensively analyzed. After several blasting vibration tests, the distribution characteristics of vibration velocity and main frequency in different directions were analyzed. The significance of elevation difference on vibration velocity in various directions was obtained through single-factor analysis. Finally, based on the dimensional analysis method, a vibration velocity prediction model under the influence of multiple factors was studied, proposed, and applied to the blasting safety charge design. The main conclusions are as follows: with the increase of floors, the primary vibration direction changes from horizontal radial (X) to horizontal tangential (Y), and finally to vertical (Z). In most working conditions, the PPV_x and PPV_y are not more than 0.17 cm/s and 0.213 cm/s, respectively, and the elevation has little influence. The PPV_z is concentrated in 0.05~0.41 cm/s, and the elevation amplification effect is significant in 7~11 layers. The maximum charge per delay, total charge amount, and horizontal distance are substantial for the three-axis PPV_s. The elevation difference is not significant for the PPV_x but significant for the PPV_y and PPV_z. The main vibration frequency is concentrated in 3~12 Hz, and some reach 16~30 Hz. Based on the vibration prediction model for the office building, combined with the blasting safety regulations and the blasting parameters under the most dangerous working conditions, the total charge of the bottom blasting should be within 10 267 kg, and the total charge of the deep hole bench blasting should be between 8268~8883 kg.