The study of damage expansion process of the surrounding rock mass under blasting is of great significance to the blast resistance design of a chamber. In order to explore the damage propagation law of the surrounding rock mass around a chamber under the action of different blasting sources, a numerical calculation model including top explosion, vault side explosion, side wall explosion, bottom side explosion and bottom explosion was established by using the finite element simulation software ANSYS/LS-DYNA. The RHT model was used to analyze the damage propagation process of the chamber surrounding rock mass at different positions. On this basis, 10 vibration velocity monitoring points were set equidistantly from the blast source to the chamber boundary in the model, and the vibration velocity attenuation law from the blast source center to the chamber boundary was studied. The results show the damage point first appears at the shortest distance from the blast source, and is then formed subsequently. The damage zone expands gradually along the boundary of the chamber and finally forms the damage zone. Compared with the decay law of the blasting vibration velocity, the blasting vibration wave is fully reflected in the surrounding rock mass, which makes the blasting vibration velocity appear an amplification effect. At the same time, the damage evolution from the blast source to the surrounding rock mass corresponds to the change law of the peak vibration velocity, which can be used to determine if damage happens.

In order to successfully demolish two brick chimneys and two reinforced concrete chimneys located in the same plant area where is a complex environment by blasting. The overall blasting scheme of “single cut, directional collapse” is determined to demolish the four chimneys at one time, by analyzing the surrounding environmental conditions and the structural characteristics. According to the engineering experience, it is determined that the bottom edge of the chimney cut is at the elevation of+0.5 m, the cut angle is 215°, the cut height, cut length and relevant blasting parameters are calculated by theoretical formula. The cut form is trapezoid like, and the initiation network uses the digital electronic detonator initiation system with higher accuracy to initiate in the way of parallel firing. Considering the different structural composition of the four chimneys, corresponding pretreatment schemes are formulated respectively. Through the safety check of the collapse reliability, blasting vibration and collapse vibration of the chimneys and the effective control of the flying debris and flying stones after blasting, the four chimneys collapse in the design direction and prevent harm to the surrounding protection targets. By using the finite element software LS-DYNA to simulate the collapse process of four chimneys, the results show that the simulated collapse process is almost the same as the actual process, and the collapse completion time is around 14 s. Moreover, by analyzing the displacement and velocity law of the top node, it can be judged that the chimney collapse effect is sufficient and the expected goal is achieved, which further shows a guiding significance of the numerical simulation for engineering practice and can provide reference for similar projects.

In order to determine the degree of impact of blasting vibrations on main haulage roadways and surface buildings near an underground mine, and to control these effects, it is necessary to obtain field test data through industrial experimentation. The Blast-NET blasting monitoring instrument was first used to monitor the radial, tangential, and vertical vibration velocities and frequencies caused by the blasting. According to the Sadovsky formula, the K and α values related to geological conditions were calculated using single-factor regression analysis, and the actual blasting vibration velocity calculation formula was obtained. The reliability of the calculation formula was then verified through continuous vibration monitoring, and optimization experiments were conducted on three different blasting network configurations: row-by-row, segmented, and hole-by-hole. The research results showed that if the protection of surface buildings is considered, the minimum safe distance between the source of the explosion and the protected buildings is 250 meters, 200 meters, and 125 meters respectively for row-by-row, segmented, and hole-by-hole blasting. If the protection of underground haulage roadways is considered, the minimum safe distance between the source of the explosion and the protected roadways is 30 meters, 25 meters, and 25 meters respectively for row-by-row, segmented, and hole-by-hole blasting. Finally, it is concluded that when the predicted vibration velocity meets the requirements of row-by-row or segmented blasting, the mine can use nonel detonators for blasting. If the hole-by-hole blasting network is required, only digital electronic detonators or high-precision nonel detonators can be used.

The average lumpiness of ore rock is an important index to measure the blasting quality. The early research mainly relies on empirical formula summary, rock mechanics model calculation, which have shortcomings such as insufficient accuracy and strong subjectivity. Recently,, machine learning algorithm is applied for prediction, but still have problems such as empirical feature selection, insufficient model prediction stability, and poor generalization ability for the prediction of blasting material fragmentation. Aiming at above shortcomings, an extreme Gradient Boosting (xgboost) blasting fragmentation prediction model based on Feature Engineering is proposed. Taking Yuanjiacun Iron Mine in Taiyuan as the research area, engineering data are collected, Random Forest (RF) and Mutual Information (MI) are used for feature selection respectively, and the two feature subsets are integrated to obtain the best feature subset based on the value of MSE. XGBoost is used to predict the block size on the optimal feature subset, and the evaluation system is composed of two indexes: Mean Square Error (MSE) and Mean Absolute Error (MAE). The proposed method is compared with other traditional machine learning algorithms, and the results show that it is better than others. Furthermore, it can provide scientific guidance for the management and control of blasting.

At present, there are some problems such as inadequate implementation of safety management measures and heavy burden of supervision departments in the special storage for civil explosives in commercial blasting operation units. Thus, the damage and economic burden to the blasting operation unit caused by explosion accidents of civil explosives storage are analyzed and illustrated by case studies. Combined with the new requirements of “fundamentally eliminate hidden dangers of accidents” in the “14th Five-Year Plan for the Safety Development of the Civil Explosives Industry” for the civil explosives industry, it is considered feasible to cancel the commercial blasting operation units owning or renting civil explosive storages that have passed the safety evaluation, from the perspective of the intrinsic safety of the civil explosive industry. Therefore, it is suggested that the Ministry of Public Security to modify or cancel the requirement of the item of 6.2.2.1 "a) (having or renting a civil explosive storage that has passed the safety evaluation) when revising the standard of the Qualification and management requirements for unit of blasting operation (GA990—2012). This measure can improve the safety production management system of the civil explosive industry, reduce the burden of the safety supervision department and the economic burden of the commercial blasting operation units, which is more conducive to the improvement of the intrinsic safety level of the civil explosive industry.

In order to study the reasonable smooth blasting parameters such as smooth blasting range, hole spacing, line charge concentration and charge structure in a fault fracture zone, empirical formula is first used for calculation. Then the blasting effect is compared by field blasts to analyze the influencing factors of smooth blasting in a fault fracture zone, so that to improve the blasting parameters and charging structure. Research results and field applications show that the smooth blasting effect is relatively good when the charge column size is ϕ 60 mm×400 mm with an uncoupled charge structure, the hole spacing is 1.2~1.5 m, the smooth blasting range is 2.5~3.0 m, the linear charge concentration is 1.2~1.4 kg/m, and the air deck length is 0.6~0.8 m. When the charge column size is ϕ 60 mm×600 mm with an uncoupled charge structure, the hole spacing is 1.2~1.5 m, the smooth blasting range is 2.5~3.0 m, the linear charge concentration is 0.7~1.0 kg/m, the stemming length is 1m,, the air deck length under the stemming is 3.0~4.0 m and the normal air deck length is 1.5~2.0 m, the smooth blasting effect is the most ideal with a smooth and stable slope. Moreover, the latter scheme has a better economic return than the former one. The selection of blasting parameters, charge structure and charge column for this smooth blasting technology can provide reference for similar projects.

Since continuous charge structure is adopted in the bench blasting of Heigou open-pit mining area, the boulder yield is high and the secondary crushing workload is large, which seriously affects the operation efficiency of the mine's subsequent production and loading shovel loading process. In order to optimize the open-pit blasting charge structure, the 2DBench module for open-pit mining in the blasting simulation software JKSimBlast is used. Taking the length and the position of the commonly used air decking as the research objects and the boulder yield as the evaluation index, 25 groups of experiments with two factors and five levels are designed with the hole depth of 17.5 m and the charge length of 10 m. The simulation results show that with the same air deck length, the boulder yield decreases first and then increases with the deck position moving down, and thus there is an optimal deck position. With the same deck position, the boulder yield decreases first and then increases with the increase of the air deck length. Furthermore, the optimal air deck length is determined as 2 m and the optimal deck position is 11.5 m from the orifice. Finally, field industrial tests with the optimized structure are carried out in 5 different blasting areas. The blasting muck pile photos before and after optimization in area 3 is selected as the reference group. By comparison, the results show that the optimized charge structure reduces the boulder yield by an average of 9.24% and effectively improves the blasting effect, which provides a useful reference for the selection and optimization of the charge structure in open pit mines.

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 demolition blasting of the tailrace outlet cofferdam of Baihetan hydropower station has obvious characteristics of tight construction schedule, heavy task, complex rock conditions, close proximity to protective objects and high requirements for slag washing by water flow. In view of the important and difficult points in the construction, a phased, partitioned and layered blasting demolition scheme was adopted, and thus the single cofferdam was divided into two phases, three layers and eight zones. By reserving an economic cofferdam and demolishing the part above water in advance, the difficulties of huge engineering quantity and tight construction schedule were overcome. The method of drilling with large-diameter drills and protecting the hole with casing effectively reduced the occurrence of hole collapse under complex geological conditions, improved the construction efficiency and ensured the blasting effect. The design of high powder factor, low single shot, inter-hole segmentation and intra-hole delay not only met the requirements of safety control of vibration velocity, but also ensured that the rock fragmentation after blasting can be washed away by water flow. The engineering application results showed that the peak vibration velocity of blasting under the most unfavorable conditions was 11.85 cm/s, which was less than the allowable safety control standard of 12 cm/s for structural concrete. The measured peak pressure of surge wave was 0.12 MPa, which was also under the allowable value of 0.4 MPa for hydraulic steel gates. The fragmentation after blasting was controlled mostly within 40 cm, and the boulder yield was controlled within 5%. The research results can provide reference for similar projects.

While excavating the rock mass by drilling and blasting method, it is bound to cause a certain degree of damage to the surrounding rock. Therefore, it has an important guiding role for the tunnel support design and longterm stability to make clear the damage characteristics of the surrounding rock during tunnel blasting excavation. Taking the blasting excavation of the Longnan Tunnel of the Ganzhou-Shenzhen High-speed Railway under Class Ⅲ surrounding rock as an example, the cross-hole ultrasonic detection method was used to detect the acoustic wave velocity of the surrounding rock in different parts of the same cross-section of the tunnel, and the distribution characteristics of the acoustic wave reduction rate were analyzed. Based on the analysis, the damage depth of the surrounding rock in different parts of the tunnel was determined, and the relationship between the damage degree and the damage depth of the surrounding rock was revealed. Based on LS-DYNA numerical simulation software, the damage evolution and distribution characteristics of the surrounding rock under 8 cyclic bench blasting under the same working conditions are simulated, which are basically consistent with the damage distribution characteristics evaluated by the acoustic wave test. The analysis results show that the surrounding rock at the foot of the arch at the upper bench has the greatest degree of damage, but with the shallowest damage depth. The maximum depth of damage to the surrounding rock is located at the bottom of the inversion arch. Based on the damage distribution characteristics, and according to the engineering analogy and relevant standards, the length of the initial supporting bolts of the grade Ⅲ surrounding rock of Longnan Tunnel should be 3.5~4 m.