Stainless steel 06Cr18Ni11Ti and cast steel 20Mn explosive welding composite plates can be used to build bridges in high alpine areas. Two groups of different welding parameters were used to investigate the weld interface characteristics of stainless steel 06Cr18Ni11Ti and cast steel 20Mn. The explosive thickness was 30 mm, the detonation velocity was 2300 m/s, and the stand-off distances were 4 mm and 10 mm, respectively. The morphology of the weld interface was studied using an optical microscope and scanning electron microscope, and the samples were submitted to tensile and flexural testing and hardness tests. Furthermore, the fracture morphology of the weld material was studied using a scanning electron microscope. In the interfacial morphology examination, the sample with a 10 mm stand-off distance had a thicker melting layer than the sample with a 4 mm stand-off distance. The melting layer thickens as the contact corrugation increases. Corrosion was observed on the cast steel 20Mn side of the weld interface enriched with austenite. The 4 mm stand-off samples did not exhibit apparent twins, whereas the 10 mm ones did. The 10 mm stand-off samples had higher interfacial deposition energy and strain rate, making twins more likely to occur. Tensile test findings indicated that all fracture separations occurred on the cast steel's 20Mn side. The shear strength of sample 1 ranged from 383.6 to 394.1 MPa, while that of sample 2 ranged from 394.3 to 408.4 MPa, showing binding strength across the interface greater than that of 20Mn. Both 10mm and 4 mm stand-off samples exhibited ductile fracture. In the 90 bending test, the welded interface shows no delamination or cracks, indicating outstanding bending performance. The hardness test results indicate that the hardness of cast steel 20Mn and stainless steel 06Cr18Ni11Ti after explosive welding are higher than that of the corresponding raw materials. Approaching the weld interface, the hardness increases noticeably. The maximum hardness for samples with a 4 mm stand-off is 413.2 HV, while for samples with a 10 mm stand-off, it is 407.9 HV. Work hardening is more pronounced on the 20Mn side of the sample with a 10 mm stand-off. The effect of hardening is much more noticeable. The fractures of the samples with 4 mm and 10 mm stand-offs display a river-like form in the fracture morphology study.

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.

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.

To investigate the influence of different blast incision central angles and heights on a cooling tower's overall collapse effect, the structure's collapse process was simulated by ANSYS/LS-DYNA finite element software. The original model was modified to explore the effects of various blasting incision's central angles and heights. Five different blasting incision heights (14 m, 15 m, 16 m, 17 m, 18 m) and three blasting incision central angles (190°, 210°, 230°) were selected for orthogonal combination to analyze their impact on the collapse effect. The results indicate that the blasting incision's central angle significantly influences the distribution range of the collapse debris, while the blasting incision height plays a secondary role. The highest point of the pile is generally located along the collapse centerline and near the transverse fracture of the tower wall. The degree of fragmentation and location of fissures on the rear tower wall determine the height and location of the highest point of the debris pile. At a fixed blasting incision height, the vertical touchdown velocity of the structure decreases as the incision's central angle increases. Conversely, at a fixed incision central angle, the vertical touchdown velocity decreases and then increases with increasing incision height. The optimal demolition parameters for the cooling tower are a blasting incision angle of 210° and a blasting incision height of 17 m.

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.

The resistance line, as a core parameter in a blast design, is closely related to rock throwing distance and fragmentation degree, thereby directly affecting the fragmentation effectiveness and the final shape of the blast pile. Due to the significant complexity of an underwater blasting project, the factors affecting the effect of underwater blasting are intricate and complex, so it is essential to explore the impact of resistance line parameters on underwater bench blasting law through both drilling and blasting tests and numerical simulations using the FLUENT-EDEM coupling method. Four resistance line cases (2 cm, 4 cm, 5 cm, and 6.5 cm) were tested. The results indicate that as the resistance line parameter increases, the proportion of adequate energy used for rock fragmentation increases, resulting in a larger blasting funnel volume. However, with further increases in the resistance line, the explosive energy per unit volume of rock decreases, and the stress wave reflection intensity weakens. Consequently, the inhomogeneity of blasting block size first decreases and then increases with the resistance line. Additionally, numerical calculations effectively replicate the model test blasting effects, demonstrating that using the FLUENT-EDEM fluid-solid coupling method to study underwater bench blasting fragmentation is practical and feasible.

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.

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.

The DBDP Hydropower Station, the largest hydropower station under construction in Pakistan, faces challenges related to blasting vibration affecting freshly poured concrete of the proposed intake tower of the diversion tunnel. Finite element calculation parameters were adjusted based on on-site blasting vibration monitoring data to address this issue. A numerical simulation method was utilized to analyze the blasting vibration response of the water intake tower under various blasting conditions and to identify factors influencing peak particle velocity (PPV). The study proposes measures to control blasting vibration. The results indicated that the maximum charge per delay, the delay time between blast holes, the advancing direction, and the detonation position significantly impact the intake tower's vibration. It is recommended that the maximum charge per delay and the delay time between blast holes be controlled to mitigate vibration on the fresh concrete. Additionally, adopting a backward blasting advancing direction and hole-bottom initiation is advisable.

The simulation test of blade loss in an aero engine plays a crucial role in casing containment design. The main challenge lies in controlling the breaking of rotor blades when they reach their maximum allowable speed. To investigate the optimal separation structure for rotor blades with artificial separation, two types of TC4 titanium alloy plates with Ⅴ-shaped grooves, one with a single hole and another with double holes at the center, were designed using explosive separation method. The selected size for the TC4 titanium alloy plate was 100 mm×80 mm×23 mm. The AUTODYN numerical simulation software's Smoothed Particle Hydrodynamics (SPH) algorithm was employed to conduct simulation calculations. Experimental comparisons were made on the damage and additional kinetic energy caused by five different schemes involving these two structures. Results indicated that scheme Ⅱ and Ⅴ failed to break off successfully, while scheme Ⅲ resulted in significant damage to the template. On the other hand, schemes Ⅰ and Ⅳ demonstrated better ability to separate the template. Under identical charge conditions, it was observed that the displacement of double-hole structured plates after fracture was significantly greater than that of single-hole structured plates with Ⅴ-grooves on both sides. Further analysis revealed that the Ⅴ-shaped slotted structure could reduce plate damage, enhance explosive energy efficiency, and minimize additional kinetic energy exerted on the plate. Moreover, compared to double-hole structures, this slotted structure also reduced peak speed by 20% and escape speed by 40%.