Addressing the engineering challenge where excessive rock fragmentation in the area near blasting source leads to over 50% energy loss of explosives, this study conducts an in-depth experimental investigation into the mechanism of rock over-fragmentation under ultra-high pressure conditions. Using granite as the research subject, soft-recovery techniques were employed to collect fragmented granite samples from the near-blasting area under varying pressures. Statistical analysis of micron-sized fragment distribution under ultra-high pressure was performed via an interactive machine learning-based image segmentation tool, with a focus on elucidating elastoplastic transitions in granite under different loading pressures and energy distribution during fragmentation. The results reveal that ultra-high pressure in the near-blasting area induces complex fracture phenomena in granite. Experiments demonstrate a shift from stepped fracture patterns to micro-cracking characteristics with increasing pressure, indicating that fragmentation energy accounts for no more than 23.68% of the total impact energy at 5.50 GPa. As impact pressure rises, rock fragment size decreases significantly while the proportion of fragmentation energy declines substantially. This research provides theoretical support and practical guidance for high-fidelity simulation of blasting processes and optimized blast design

High-throughput computing has become a cornerstone of modern materials design and is driving new advances in the study of shock-compressed matter. Central to these efforts is an accurate Hugoniot equation of state (EOS) for mixtures, yet existing mixture models continue to show sizeable scatter. Here we benchmarked two widely used schemes—the volume-additive model (Mod A) and the isothermal-average model (ModⅠ)—against experimental Hugoniot data for binary alloys, ternary alloys and granular mixtures. The Mod A model assumes full thermodynamic equilibrium and neglects the temperature rise of individual constituents under shock compression. The ModⅠ model, by contrast, removes this thermal contribution by deriving the mixture Hugoniot from 0 K isotherms via the Mie-Grüneisen EOS. Systematic comparison between the predicted Hugoniot EOS of binary alloy, ternary alloy, granular mixtures and the experimental data reveals that the ModⅠ model reproduces measured Hugoniot states within about 10% error across the entire pressure range studied, outperforming the Mod A model in both accuracy and robustness. Both approaches exhibit moderately larger discrepancies at low shock pressures, where thermal effects are most pronounced.

In the reconstruction and expansion projects of expressways, a large number of cross-line bridges cannot meet the development needs of modern transportation and are facing demolition and reconstruction. Traditional manual and mechanical demolition methods have drawbacks, including low efficiency, prolonged timelines, and substantial traffic interference. In contrast, blasting demolition-with its inherent benefits of safety, economic viability, and operational efficiency has emerged as the optimal technique for dismantling cross-line bridges on expressways. Based on the reconstruction and expansion project of the section from the Hubei-Henan boundary to Junshan on the Beijing-Hong Kong-Macao Expressway, one-time combined blasting demolition was carried out on five cross-line bridges in the K1018+990~K1048+550 section. Through the quantitative design, fine construction, and multidimensional protection of four types of bridges-such as equal-section catenary hingeless arch bridges, inclined-leg rigid frame bridges, half-through arch bridges, and steel frame arch bridges-the goal of safe and efficient blasting demolition was realized. The practical results show that the collapse mode and disintegration effect of the bridge can be effectively controlled by reasonably designing the blasting cut and initiation sequence. The distributed cooperative detonation system, based on radio communication, overcomes the spatiotemporal coordination problem of synchronously detonating group bridges over a long interval. The protection measures of ‘covered protection+near body protection’ were adopted to control the splash of individual flying debris effectively. The ‘rigid support layer+elastic buffer layer’ protection system effectively prevents the impact damage of the bridge collapse on the high-speed pavement. The engineering practices presented herein demonstrate that through meticulous design, synchronized control strategies, and multi-tiered protective measures, the safe and efficient demolition of cross-line bridge groups across extensive expressway sections in complex environments can be accomplished.

Most of the buildings in the mountain city area are built on leaning the mountains, with the characteristics of uneven terrain, scattered architectural layoutscattered layout of buildings and complex surrounding environment. In a certain area of Chongqing, there are were 10 frame-shear wall structure illegal buildings with a frame-shear structure that need to be demolished. Due to the requirements of construction safety and progress, single incision directional blasting demolition is was determinedadopted. Combined withBased on related the practice experience of blasting demolition project, according to the plane position, spatial distribution characteristics and surrounding environment of 10 illegal buildings, thean corresponding overall blasting scheme is was put forward according to the plane positionlayout, spatial distribution characteristics and surrounding environment of the 10 illegal buildings. And optimizing construction organization, tThe blasting demolition task of this building group is was completed safely and efficiently in three times within 15 days under an optimizding construction organization. In view of the environmental factors such as high and steep rock slopes, valleys and scarps that which affect the collapse of the building and the blasting effect, the directional collapse of the buildings can bewere reliably guaranteed by optimizing the blasting incisions, reserving buffer layers, and rationally designing blasting parameters. Through the rational reasonable design of the partition sections and delay times of firing circuitthe initiation network, and efficient organization of the circuit connection operations, the athe reliable delay initiation of large-scale industrial electronic detonator network is was realized. Finally, the collapse accumulation range and blasting harmful effects of building arewere effectively controlled. The collapse of eEach building is was fully disintegrated, the blasting heap piles fragments arewere concentrated, and all kinds of surrounding protection objects are were safe. The engineering practice results show that the initiation network of industrial electronic detonators initiation network can meet the needs of multi-unit and multi-level large-scale initiation network, which provides an important reference for similar projects.

It is prone to occur dynamic disasters such as roof falling, sidewall slabbing and rock burst under dynamic disturbance of mechanical percussion drilling and explosive blasting in the roadway with hard rock. It is extremely meaningful to investigate the dynamic load effect on roadway deformation and failure mechanism. To understand the mechanical behavior of roadway surrounding rock under dynamic disturbance, a hard rock roadway was simplified as a hole in rock. And then, a series of impact tests were conducted on prismatic sandstone rock specimens with a hole by a modified split Hopkinson pressure bar testing system to explore the influence of hole size and shape on the dynamic mechanical properties, failure mode and energy dissipation characteristics. The results show that the existence of the hole has significant weakening effects on the dynamic strength, dynamic elastic modulus and peak strain. The dynamic mechanical properties of the rock decrease significantly with the increase of hole size. Among the specimens with different hole shapes, the dynamic strength and peak strain of the square-holed specimens are the largest, followed by the horseshoe-holed and the circle-holed specimens, but their elastic moduli show opposite results. In terms of rock failure modes, splitting tensile and tensile-shear failure occur respectively in intact specimens and pre-holed specimens under impact load. Additionally, the energy consumption density and fractal dimension of the horseshoe-holed specimens are the largest, which are 1.94 J/cm³ and 2.11 J/cm³, respectively. It indicates that the failure process is the most intense for the horseshoe-holed specimens, while the fragmentation degree of the circle and square holed specimens is not much different.

In order to investigate the influence mechanism of steel fiber content on the dynamic compression and tensile mechanical properties of concrete, this study conducted dynamic compression and dynamic Brazilian splitting tests on concrete samples with varying impact pressure and steel fiber volume contents(0%C50 element concrete, 2%, 3%, and 4%) using a Hopkinson pressure bar(SHPB) device. Additionally, high-speed photography was employed to reveal the dynamic evolution process of cracks. The test results demonstrate that under the same impact pressure, both the dynamic compressive strength and dynamic splitting tensile strength of steel fiber reinforced concrete samples exhibit a positive correlation with the content of steel fiber. Furthermore, there is also a positive correlation between energy absorption capacity and degree of crushing, indicating that steel fibers effectively inhibit concrete crushing while preventing excessive energy absorption and dissipation in these samples. The upper limit for energy absorption rate in steel fiber reinforced concrete samples ranges from 30% to 36%. Notably, compared to its effect on dynamic compressive strength, steel fibers significantly enhance the dynamic splitting tensile strength of concrete. For applications requiring high-strength or anti-violence characteristics in combination with cost-effectiveness, technical controllability, and test data analysis; incorporating a reasonable range for toughening can be achieved by including 2%~3% steel fiber content into high-strength concrete. Moreover, it is important to note that the action mechanism of steel fibers differs when considering their effects on both dynamic splitting and compression failure in concrete samples. Steel fibers significantly impede crack propagation during dynamic splitting processes; however, separation between the fibers themselves leads to ineffective toughening during dynamic compression."

Reinforced concrete (RC) short beam is the key load-bearing component of buildings. In order to study its dynamic response and failure mechanism under impact load, drop hammer impact tests with different impact mass, impact velocity and impact energy were carried out by combining strain gauge sensor, high-speed photography and digital image technology (DIC). The results show that, the failure forms of the short RC beams under impact loads are arch collapse cracks and overall bending deformation, which are obviously different from those of shallow beams. The axial strain in the mid span of a short RC beam changes from tensile strain to compressive strain. With the increase of impact energy (18 061 J≤E≤49 831 J), the axial peak tensile strain and residual compressive strain in the mid span increase first and then decrease. The short RC beam is in the stage of elastic flexural deformation, elastic-plastic flexural deformation and punching shear failure mode in turn. The crack initiation and propagation process of the short RC beam under impact load is not unidirectional. And the fracture zone is formed by the multidirectional fracture propagation with multiple times, and then the plastic hinge is formed, resulting in the overall short beam failure. The deformation degree of the beam mainly depends on the impact speed rather than the impact energy. Specifically, the peak deflection and residual deflection in the middle span of the beam (26.81 mm≤w_p≤29.85 mm;17.12 mm≤w_r≤21.66 mm) increase with the increase of the impact speed (5.53 m/s≤v≤7.13 m/s) under the same impact energy (30 000 J).