To study the dynamic damage and fracture of metamorphic limestone under explosive load and the stability of the surrounding rock, the stress-strain curve, fracture morphology, and energy dissipation characteristics of metamorphic limestone in the Dahongshan mining area under different strain rates were studied by the Hopkinson pressure bar (SHPB), stress wave analysis, and fractal theory. The experimental results show that the crushing form and degree are significantly affected by the loading strain rate. There are several typical failure modes. When the strain rate is 17.56 s⁻¹, there is no obvious failure except corner cracks. When the strain rate is between 26.92 s⁻¹ and 56.18 s⁻¹, the failure mode of the specimen is axial splitting failure, and when the strain rate is 67.34 s⁻¹, splitting and shearing failure occur. With the increase of the strain rate, the growth rate of the dynamic compressive strength slows down. Compared with static compressive strength, the strength factor increases from 1.15 to 4.19. Also, the fractal dimension shows a gentle increase. When $Df$ is in the range of 1.82~2.24, there is a sudden change in fragmentation when the strain rate is in the range of 34.70 s⁻¹~56.18 s⁻¹. Energy dissipation density increases logarithmically with the strain rate. The results reveal the dynamic breaking and energy consumption laws of metamorphic limestone under impact loads with different strain rates and could provide some reference value for the safe and efficient construction in the Dahongshan mining area and similar engineering projects.

This article aiming at the lack of research on the influence of rock clamp production on cutting blasting under high in-situ stress conditions and the lack of rock damage criteria for RHT constitution in numerical simulation. Combined with the critical rock damage criterion and the embedded function of RHT constitution, the criterion for determining the critical damage of rock in RHT constitutive was studied, and the mechanical parameters of Metamorphic sodium lava were substituted to obtain the critical damage threshold of rock in numerical simulation. The smooth particle hydrodynamics (SPH) method was used to numerically simulate and analyze the influence of different rock clamping coefficients on the rock damage range and the cavity area in the cutting blasting. The stress state applied by the numerical simulation was inversely deduced by the field test scanning results to simulate the rock clamping coefficient K_r at the corresponding depth. The relationship between the cavity area S_c and the free surface distance D_f is analyzed and established. The results show that the rock clip production has an inhibitory effect on the development and propagation of blast-induced cracks. The stress applied in the numerical simulation affects the range and development degree of cracks, and the cracks generated by the explosion are mainly circumferential cracks. The larger coefficient of rock clip production, the more obvious the inhibitory effect on cut blasting, the less the blast-induced cracks and the smaller the rock damage circle. The fitting results show that the curve fitting degree is about 0.94, which proves the accuracy of S_c-D_f curve, and provides important reference value for the design of one-time completion blasting of upward blind shaft.

Precise control of casting velocity and effective throwing kinetic energy conversion efficiency in blasting engineering are challenges. To provide a theoretical basis and reference for the implementation plan and fine construction of the cast blasting project, we study the problems of casting velocity and energy consumption ratio of broken rock under the impact load of explosions in this manuscript. The calculation methods of casting velocity and throwing energy of broken rock under two blasting modes of spherical charge and cylindrical charge are established by using the theory of dimensional analysis and rock breaking by blasting. A large number of model tests are carried out by using high-speed photography. The results indicate that the casting velocity of broken rock after explosive initiation has two evident stages: instantaneous acceleration to a certain value and subsequent fluctuation; the velocity presents an ordinary distribution law with the step height, and the fitting correlation of high-speed photography results is more than 91%. With the minimum burden increasing from 0.12 m to 0.2 m, the energy consumption decreases from 1306.88 J to 747.49 J and the proportion of energy consumption decreases from 14.77% to 8.45%.

Cutting blasting is the principal construction method for roadway and shaft excavation, but the studies on the damage mechanism of cutting blasting affected by the volume effect of empty holes under high ground stress are not insufficient. During cutting blasting, different damage zones are formed. In this paper, combined with the rock damage criterion and RHT constitutive function, the ranges of these damage zones are determined. The smooth particle hydrodynamics method is used to study the influence of high in-situ stress on rock blasting damage from the perspective of the number of empty holes and the production coefficient of rock clamp. The accuracy of the determined damage zone range is verified by supplemented field tests. The research results show that in the process of rock clamp production, the propagation of blasting stress wave is inhibited, especially the tensile stress wave which is more obviously inhibited. The empty holes reduce the inhibitory effect of rock clamp production. With the increase in the production coefficient of rock clip, the blasting damage radius is reduced by 39.7%, 35.1%, 30.5%, 26.7%, and 22.9% compared with the theoretical value, respectively, while its influence on the radius of crushing zone is small. The three-dimensional scanning results were used to inverse calculate the production coefficient of the rock clip. The fitting degree between the numerical simulation and the field test scanning results is about 94.5%, which proves the accuracy of the RHT constitutive parameters and the reliability of the determination range. The mathematical relationship between the production coefficient K_r for rock clip and the relative height H of the wellhead and the area S_c of the cross-section cavity is fitted based on the data of several upward cutting blasting field tests.

How to achieve high-precision detection and real-time deployment of the lithology intelligent identification system has significant engineering implications in the geotechnical, geological, water conservation, and mining disciplines. In this study, a lightweight lithology intelligent identification model is proposed to overcome this problem. The MobileNetV2 model is utilized as the basic backbone network to decrease network operation parameters. Furthermore, channel attention and spatial attention methods are incorporated into the model to improve the network’s extraction of complicated and abstract petrographic elements. In addition, based on the findings of network training, computing power performance, test results, and Grad-CAM interpretability analysis and comparison tests with Resnet101, InceptionV3, and MobileNetV2 models. The training accuracy of the proposed model is 98.59 percent, the training duration is 76 min, and the trained model is just 6.38 megabytes in size. The precision (P), recall (R), and harmonic mean (FI-score) were, respectively, 89.62%, 91.38%, and 90.42%. Compared to the three competing models, the model presented in this work strikes a better balance between lithology recognition accuracy and speed, and it gives greater consideration to the rock feature area. Wider and more uniform, strong anti-interference capability, improved robustness and generalization performance of the model, which can be deployed in real-time on the client or edge devices and has some promotion value.

In order to prevent rockfall caused by open‐pit blasting on the high and steep slope and ensure that the passive protective net structure has sufficient impact resistance, the mechanism of blasting flyrock causing rockfall is analyzed by using ANSYS/AUTODYN to establish the model of rockfall and passive protective net; at the same time, the influences of protective net size, rockfall kinetic energy, and rockfall size to the protective effect were also studied. The results show that under the condition of the same rockfall kinetic energy and rockfall size, the larger the size of the protective net, the longer the buffer time, and the impact force that net can sustain is greater; by assuming the protective net size and rockfall size to be a constant, the greater the rockfall kinetic energy, the less the interaction time between rock and net, and the greater the impulse force that net can suffer; similarly, by keeping the protective net size and the kinetic energy of rockfall to be a constant, it is found that the larger the size of the rockfall, the larger the interaction area and longer interaction time with the net, and the less net will be disrupted; the protective net used in the mine can intercept the rockfall caused by flyrock in blasting process effectively and ensure the safety of villager at the foot of the mountain.