A parameterized hole placement design method for medium-depth holes was proposed to solve the problems of large subjectivity of manual interaction, cumbersome and complex adjustment of hole placement and difficulty in ensuring the uniformity of hole bottom distance. Firstly, a mathematical model in underground mines was constructed using the parameterized hole layout idea combined with the blasting boundary space constraints and blasting parameter requirements. Furthermore, the mathematical model was solved using the operation research method to get the optimal hole design on a digital mining software platform. Finally, the model was used in an underground mine. The result shows that the standard deviations of the bottom distance for the manually laid holes are 0.08 m, 0.10 m, 0.07 m and 0.07 m, respectively, while those for the automatically laid holes with the parameterized method are 0.02 m, 0.03 m, 0.02 m and 0.02 m, respectively. The hole laying time is shortened from 4 hours to 5 min. The proposed method significantly reduces the workload of the designing technicians and maximizes the guarantee of inter-hole laying between holes. It maximizes the uniformity of the bottom distance and avoids the randomness and errorprone nature.

The rock mass joints can affect the propagation of explosive stress waves. The angle between their direction and the surrounding holes and the relative position changes have different effects on the blasting effect. Based on the attenuation law of stress waves at different jointed angles, a method was proposed for zoning the surrounding holes of tunnel blasting in jointed rock masses. The parameters of the surrounding holes are optimized when the angle between the joint and the surrounding hole is 30°, 60°, 90°, and 0° (parallel). The zoning layout method was validated by combining LS-PREPOST numerical simulation and on-site tests regarding rock damage depth and blasting vibration speed. The results show that the rock mass's damage depth and blasting vibration speed under the zoning arrangement of surrounding holes are significantly better than that of the original layout plan of surrounding holes. Based on the geological conditions of the research section of the Bayueshan Tunnel of the Tongliang Anyue Expressway, the angles between the joints and the surrounding holes are set to 30°, 60°, and 90°, respectively. The spacings between the surrounding holes are set to 43 cm, 50 cm, 58 cm, and 60 cm when the joints parallel the surrounding holes. The average over-excavation value can be controlled at 18cm after blasting, and the over-consumption of concrete is controlled within 100% per linear meter.

With the continuous development of precision step blasting technology in open pit mines, the disadvantages of traditional layout methods in layout precision and construction efficiency are becoming more and more prominent. In order to improve the precision and efficiency of hole layout, the theory of hole layout is combined with RTK line lofting technology. According to the designed values of the chassis resistance line, hole spacing and row spacing, the RTK line lofting method is used to measure the size of the chassis resistance line and determine the line coordinates and layout direction of the first row of holes. Then, each row of holes can be laid out for construction by setting parameters such as mileage, mileage increment, deviation and deviation direction in the RTK manual book. Finally, a single person can achieve high-precision and high-efficiency hole laying while recording the hole position and measuring the design hole depth. This paper introduces a construction method of RTK line lofting and hole layout in detail, applies it to the actual construction, and gets a good effect. Applying this method provides a new idea for the precision, standardization and high efficiency of the open-pit bench blasting construction, improves the construction efficiency and precision while saving workforce, and reduces the cost of open-pit blasting.

There are hundreds of blast holes in a tunnel blasting. Since the traditional manual drawing of the blasting scheme is laborious and depends on the experience of blasting engineering, a digital method for the planar and three-dimensional spatial distribution of blast holes was proposed based on formula derivation to study an intelligent design method for tunnel blasting blast holes. Subsequently, the programming of blast hole parameters was achieved by utilizing computer programming techniques, which can lead to the development of an intelligent blast hole design system. The results show that the parametric expression method of tunnel contour, cut holes, peripheral holes and auxiliary holes can realize their rapid creation and meet the needs of tunnel blasting. By establishing a correlation between the coordinates of the blast hole opening and bottom, a refined expression of the spatial distribution of the blast hole can be realized, and intuitive guidance for on-site drilling operations can be provided. Furthermore, a computer programming method can realize an intelligent and fine design of a blast hole layout. After tunnel blasting, the residual marks of the blast holes are complete, the contour of the tunnel excavation is smooth, and the overall excavation effect is good. The research results can improve the efficiency and intelligence of tunnel blast hole design.

For the blasting and demolition project of a 130 m multi-tube sleeve chimney, the LS-DYNA finite element software was used to simulate the blasting incision by unit failure using a separated common-node model. The collapse process of the multi-tube sleeve chimney was numerically simulated, analyzed and compared with the actual blasting effect. The results show that the effective stress is mainly concentrated on the edge of the remaining part of the support when the blasting notch is forming. However, the notch closure stage of the falling speed is different due to the length and slenderness ratio and the nature of the material of the outer chimney and the inner sleeve are different. The simulation shows that the external chimney and the steel inner tube would be collisional at the notch closure stage as the internal and external detonation simultaneously. Choosing the detonation method with a delay of two seconds between internal and external components will achieve the ideal collapse effect.

To investigate the rock mass crack propagation pattern in deep-buried tunnels during drilling and blasting excavation, two combined model tests (labeled as Model 1 and Model 2) consisting of multiple cement mortar blocks were carried out. The dimensions of the models were both 180 cm×80 cm×25 cm (length width height). Among them, the matrix size was 60 cm×80 cm×25 cm, and two sides had single and multiple joints. Furthermore, a thorough analysis was conducted to determine the influence of dynamic loads stemming from nine cumulative explosions on the crack propagation in a matrix by applying various static stresses, particularly on the direction of the applied static loading. The experimental results reveal that cracks emerge on both Model 1 and Model 2 surfaces along the direction of static stress loading when the static stress increases from 0.5 MPa to 5 MPa. The crack propagation direction forms an angle on the loading direction, and the main crack is longer than 60 cm. A blasting funnel contour with about 30 cm diameter is formed on the bottom of Model 1, which does not fall off. In comparison, a funnel with about 52 cm diameter and a 10 cm depth is formed on the bottom of Model 2, which has fallen off. Numerical analysis verified that the static stress has a guiding effect on the propagation direction of blasting cracks, which is consistent with the model test results. The difference was that the length of the main crack calculated by numerical calculation was smaller than that of the model test. Finally, the reason for this deviation was analyzed.

Abstract: A patented technology for bus current acquisition of electronic detonators is introduced, which uses a low-cost hardware solution to achieve high-precision and wide-range current acquisition. This technology is designed to monitor and acquire data related to the working current, communication current, charging current, and detonator bus current load for electronic detonators, thus enabling these devices' status monitoring, data communication, and bus protection. This system focuses on the innovative, low-cost circuit design concept and the methods employed to ensure high-precision, high-resolution, and wide-range current acquisition. The typical working current of the electronic detonator control module ranges between 10~30 uA, and data is transmitted to the detonation controller via a current carrier. The communication current typically falls within the 0.5~2 mA range, and the ignition energy storage capacitor is charged through the bus with a peak charging current of 1~2 mA. The detonation controller determines the working status of the electronic control module by acquiring bus current data, which includes communication and charging status, to determine the module's working condition. In the current acquisition method discussed, low-side resistors are used to sample the current, replacing a differential comparator with three low-cost operational amplifiers. Furthermore, a 12 bit AD converter integrated into the MCU replaces an external 16-bit AD converter, which reduces hardware costs by over 80%. By segmenting the current collection, the system maintains the required accuracy for small current sampling and expands the current sampling range by 30 times, covering the rated current of the bus. The absence of an external AD conversion module significantly improves the sampling efficiency.

The intrinsic mode confusion of empirical mode decomposition (EMD) and the ensemble empirical mode decomposition (EEMD) can only suppress mode confusion to a limited extent, as the white noise added by EEMD cannot be fully neutralized, which compromises the completeness of the original signal. Additionally, both methods fail to avoid interference from endpoint effects. Modal confusion and endpoint effects lead to distortions in the time-frequency analysis results obtained from the Hilbert transforms of EMD and EEMD. A complete ensemble empirical mode decomposition with adaptive noise and endpoint processing (EP-CEEMDAN) is proposed to address these issues. Simulation experiments were conducted to compare EMD, EEMD, and EP-CEEMDAN decomposition results on simulated vibration signals. Through multiscale permutation entropy detection and marginal spectral analysis, it was verified that EP-CEEMDAN has better control over endpoint effects and mode confusion, proving that EP-CEEMDAN is a more effective adaptive algorithm than EMD and EEMD. Finally, EP-CEEMDAN was applied to the processing of measured non-stationary vibration signals, where adaptive white noise was added at the endpoints of the vibration signals during each stage of decomposition. The method successfully generated various intrinsic mode functions (IMF) by calculating a unique residual signal. The EP-CEEMDAN algorithm effectively suppresses IMF endpoint divergence and modal confusion, while the time-frequency spectrum obtained through the Hilbert transform offers high resolution in both time and frequency domains. This result can be used for vibration feature recognition in non-stationary vibration signals.

Abstract: Vibration is a primary detrimental effect generated by blasting operations, and accurately evaluating its impact remains crucial and challenging. Based on the blasting excavation of a tunnel under the Central Yunnan Water Diversion Project, this study combines numerical simulation and field investigation to assess the damage characteristics of buildings affected by various factors. The results show that blasting vibration causes “X-shaped” cracks at the four corners of windows and doorways, while uneven settlement leads to 45° diagonal cracks. Subsequently, time-frequency analysis was performed on vibration data from buildings at varying distances from the blast source. The findings indicate that forced vibration predominates in building foundations, with minimal free vibration and quickly attenuating after the blasting load ends. As horizontal distance increases, the main frequency and blasting vibration energy exhibit a downward trend based on Fast Fourier Transform (FFT) analysis. However, the main frequency is less sensitive to distance changes than energy. Additionally, the sensitivity of energy to distance varies across different frequency bands. Generally, energy in each frequency band rapidly attenuates close to the blast source, with slower attenuation as distance increases. Furthermore, as the distance from the last source increases, there is a shift in energy from higher to lower frequency bands towards lower frequency bands, and the effect of low-pass and high-filter results in distinct variations in energy attenuation within different frequency bands. Finally, the study highlights a significant disparity between human perception of blasting vibrations and building safety standards. Based on this observation, a comprehensive evaluation method is proposed to combine structural damage assessment with considerations of the human settlement environment.

Since uneven stress on the cutter head can easily lead to surface collapse accidents when a shield machine passes through the silt-rock strata, the rock stratum can be blasted and broken by drilling blast holes on the ground surface before the shield machine arrives. However, the seismic waves generated by the blasting would threaten the safe operation of adjacent gas pipelines. In order to study the vibration characteristic of adjacent gas pipelines during blasting in silt-rock strata, the rock breaking project of silt-rock strata in the shield section of Hengqin Station and Hengqin North Station of Zhuhai Metro was selected as the research background. Firstly, the on-site blasting vibration was tested. Then, the ANSYS/LS-DYNA software was used to simulate the blasting process and invert the physical and mechanical parameters of the materials at the blasting site. Finally, the vibration characteristic of the gas pipeline was analyzed. The research results show that the PPV (peak particle velocity) on the pipeline decreases with the increase of the horizontal distance from the explosion source in the axial direction of the gas pipeline. Meanwhile, the maximum PPV position is perpendicular to the center line of the blast holes. Furthermore, the surface PPV above the gas pipeline decreases along the pipeline axis as the horizontal distance from the explosion source increases, and the maximum PPV position is also perpendicular to the center line of the blast holes. Besides, there is a functional relationship between the surface soil PPV₂ along the axial direction of the gas pipeline and the PPV₁on the outer wall of the gas pipeline, which is V₂=0.60V₁+1.29. More importantly, the PPV of the gas pipeline's inner and outer of the gas pipeline are basically the same.