In view of the rockfall impact threat faced by buried pipelines in high-risk areas of geological disasters, this study systematically investigated the dynamic response characteristics of buried pipelines through a combination of scale model test and numerical simulation to further explore its dynamic response characteristics and dig deep into their intrinsic mechanisms. A test model with a geometric scale ratio of 1∶10 was constructed. Meanwhile, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipeline burial depth, wall thickness, impact parameters, pipeline parameters, and soil properties (including soil elastic modulus and pipe-soil friction coefficient) on buried pipelines were explored. The test results show that at the same impact height, the peak strain decreases as the pipeline’s burial depth and wall thickness increase. Under eccentric drop hammer impacts, the influence on the upper and lower cross-sections of the pipeline diminishes as the impact point deviates from the pipeline center. Additionally, a higher impact height corresponds to a greater peak strain in the middle section of the pipeline.The numerical simulation results indicate that the maximum stress and strain of the pipeline are positively correlated with pipeline diameter, internal pressure, and impact velocity, while negatively correlated with impact eccentricity, soil elastic modulus, and pipeline burial depth. Moreover, the increase in the pipe-soil friction coefficient has a limited impact on pipeline stress and strain, and this effect becomes negligible when it exceeds 0.3. Based on Pearson correlation analysis, the order of influence degree of each parameter is impact eccentricity, pipeline internal pressure, pipeline diameter, soil elastic modulus, and pipe-soil friction coefficient. Among them, pipeline internal pressure, pipeline diameter, and pipe-soil friction coefficient are positively correlated with strain, while soil elastic modulus and impact eccentricity are negatively correlated with strain. The rockfall impact eccentricity and pipeline internal pressure have a moderate to strong correlation with the impact response of buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.

In response to the existing problems in the temperature monitoring of boreholes in high-temperature fire areas of open-pit coal mines, this study proposed an intelligent temperature monitoring and early warning system by integrating fiber Bragg grating (FBG) temperature measurement with wireless communication and developing an automatic water injection cooling (failure) module. Based on similarity theory, we established a physical model for the rock strata of the fire area, and built a laboratory simulation system to simulate the temperature field distribution in the high-temperature fire area. Temperature at multiple points in the boreholes was monitored in real time by FBG sensors, and the temperature measurement data were transmitted via wireless communication. The reliability of this scheme was verified. Results show that compared with traditional thermocouple temperature measurement, FBG temperature measurement exhibited higher stability and measurement accuracy in high-temperature environments and could monitor and transmit temperature data in the boreholes in real time. Under varying initial temperature, when the heat release rate of the heat source was equal to the heat dissipation rate, the system automatically stopped water injection with the equilibrium temperature as the dynamic threshold. The cooling (failure) module could trigger water injection when the borehole temperature reached the corresponding high-temperature threshold (80, 90, 104 ℃), and the temperature dropped rapidly below the low-temperature threshold (60, 70, 90 ℃). The sensors near the borehole mouth showed temperature fluctuation attenuation of about 18% due to heat dissipation. The system thus forms a closed-loop solution featuring precise temperature measurement, intelligent early warning and rapid cooling.

When using the blasting caving method to treat goaf, the collapsing ore and rock can cause shock disturbances to the roof of the lower stope, which may lead to stability risks. This study takes the goaf treatment project of Baiyinnuoer No.1 ore body for analysis to protect the stability of the lower stope roof. Specifically, HJC constitutive parameters were calibrated using the physical and mechanical parameters of the ore and rock; SHPB tests were conducted to investigate the dynamic constitutive behavior of the ore and rock, and the reliability of the HJC constitutive model was verified through simulation results. Using LS-DYNA and HJC constitutive parameters, the inter-row delay time was simulated and optimized for insulating pillar blasting caving. Results show that under low impact air pressure, the dynamic stress-strain curves of both types of ore exhibit hysteresis effects. At identical impact pressure, the insulating pillar specimen shows limited damage, while the ore in the lower stope roof experiences more severe fragmentation. In the simulation under different inter-row delay times, the 100 ms working condition yields significant stress superposition effect, extensive disintegration of the insulating pillar, through-going cracks at the top, and failed unit of 998 m³. The collapsed insulating pillar after blasting forms an effective buffer layer in the goaf, isolating the open-pit mine from the underground space, and preventing the instability of the lower stope roof caused by shock disturbances. The peak particle velocity at the tunnel blasting vibration measurement point was 0.64 cm/s, much lower than the allowable lower limit of 15.0 cm/s.

During drilling and blasting of open-pit mining in high and cold regions, water inrush or freezing often occurs on the borehole inside. This phenomenon creates a decoupled charge structure with water and ice, affecting the blasting effect and the rock-breaking mechanism under decoupled conditions. To determine the geometric parameters of the blasting crater and analyze the blasting effect under three types of decoupling medium in the high-cold area, a series of tests were conducted on the blasting effects of different decoupling charges in the Karma open-pit mining in Tibet. Based on the Livingston curve fitting results, the blasting parameters were optimized and applied to on-site engineering blasting. The results indicated significant differences between the visible volumes of the blasting crater and the crushed funnel at burial depths of 1.09~1.49 m. However, these volumes resembled burial depths of 1.49~1.69 m. Compared to the air-deck decoupling, the peak particle velocities under water and ice decoupling were reduced by 25.33% and 11.24%, respectively. The critical charge depths varied among the three decoupling materials, with water decoupling having the most significant critical depth, ice decoupling charge, and air-deck decoupling having the shallowest. The charge weights required for water and ice decoupling and ice decoupling were 18.9% less than those for air-deck decoupling. In multi-hole bench blasting, the explosive factor for water and ice decoupling was reduced by 18.2% compared to air-deck decoupling, and the rate of large fragments decreased from 8.9% to 4.3%. This indicated that water and ice decoupling charges made the energy distribution of explosives more uniform.

In order to analyze the failure characteristics and strain evolution law of reinforced concrete columns after blasting under different amount of explosives per unit area and section stresses, blasting tests of 12 reinforced concrete columns were carried out by using a self-developed test system with uniaxial inertial dynamic loading model, which is based on the theory of elastic mechanics. When the upper section stress of the reinforced concrete columns was 0 MPa, the corresponding amounts of explosives per unit area were 0.11 kg/m², 0.23 kg/m², 0.27 kg/m², respectively. When the upper section stress was 2 MPa, the corresponding amounts of explosives per unit area were 0.13 kg/m², 0.18 kg/m², 0.23 kg/m², respectively. When the upper section stress was 3 MPa, the corresponding amounts of explosives per unit area were 0.18 kg/m², 0.23 kg/m², 0.32 kg/m², respectively. When the upper cross-sectional stress was 4 MPa, the corresponding amounts of explosives per unit area were 0.13 kg/m², 0.18 kg/m², 0.23 kg/m², respectively. In addition, numerical simulation software was used to analyze the impact of different section stresses on blasting effect. The longitudinal central axis crushing distance is defined to describe the crushing range of the column after blasting, and the central axis crushing distance and strain evolution law are analyzed under different influencing factors through theoretical deduction, field experiment and numerical simulation. The analysis results show that with the increase of section stress, the greater the coupling tangential stress close to the central axis, and the coupling tangential tensile stress which is perpendicular to the loading direction is relatively reduced. When the amount of explosive per unit area is less than 0.15 kg/m², the crushing range of the central axis of the column decreases with the increase of the section stress. When the amount of explosive per unit area is more than 0.15 kg/m², with the increase of section stress, the crushing range continues to increase. The peak of tangential tensile strain shows an upward trend, and the absolute value of the peak radial compressive strain gradually decreases. When the section stress is fixed, the crushing range of the column increases with the increase of the amount of explosive per unit area, but the growth rate decreases with the increase of the amount of explosive per unit area. Meanwhile, the peak of the tangential tensile strain of the column increases, and the absolute value of the peak radial compressive strain also shows an upward trend. With the increase of section stress, the crushing range in the column damage cloud is increasing, and the crack tends to extend axially with the load, which further verifies the correctness of the test conclusions.

The building to be demolished was a framework-tube structure with high structural strength and good stability. It was located in a densely populated area with a complex surrounding environment. To determine a reasonable blasting demolition plan, the “three-dimensional gradual detonation” method was proposed, which was a way of detonation that achieves spatial delay by differentiating the delay time of adjacent blasting column holes in the horizontal and vertical planes of the blasting notch. Then, ANSYS/LSDYNA finite element software was used to simulate and analyze three different blasting schemes: V-shaped detonation, symmetrical detonation, and “three-dimensional gradual detonation” with a delay time of 0.50 s. By comparing the shape and range of blasting muck pile, and energy changes when the structure touches the ground, the blasting scheme “three-dimensional gradual detonation” with a delay time of 0.50 s was finally determined. The results showed that compared with symmetrical detonation, the “three-dimensional gradual detonation” reduced the kinetic energy when the structure touched the ground by 50% and increased the internal energy by 47%.Compared with V-shaped detonation, the kinetic energy when the structure touched the ground was reduced by 36%, and the internal energy was increased by 31%. The use of “three-dimensional gradual detonation” reduces the collapse vibration of the structure and completely disintegrates it, reducing the range of the blasting muck pile. When the delay time is 0.50 s, the width and length of the blasting muck pile and the collapse vibration of the structure are smaller than when the delay time is 0.25 s. The numerical simulation time for the upper part of the structure touching the ground was 3.8 s, while the actual time was 4.0 s. The final formation of the blasting muck pile was at 6.0 s, and the numerical simulation of the building collapse process and the range of the blasting muck pile was in basic agreement with the actual blasting effect.