Aiming at the problem of high boulder yield under different thicknesses of frozen soil in high latitude and alpine region, blasting crater tests were carried out at low temperatures in winter in Unugtushan copper-molybdenum mine. According to the test results, the relationship between the charge parameters and the blasting crater parameters is determined by using the Livingston blasting crater theory. Simultaneously, the deformation energy coefficient of the frozen soil layer is calculated, and the blasting crater characteristic curves of different frozen soil thicknesses are analyzed. When the charging amount is 4 kg, the critical depth of the frozen soil is 1.3 m, the optimal depth is 0.84 m, and the deformation energy coefficient is 1.06. When the charging amount is 8kg, the critical depth of the frozen soil is 1.7 m, the optimal depth is 1.2 m, and the deformation energy coefficient is 1.05. When the charging amount is 12kg, the above parameters are 2.2 m, 1.34 m and 0.95, respectively. According to the similarity law, the optimal charging parameters which are suitable for the frozen soil area on the site are derived, the blasting effect under multiple blasting parameters of different frozen soil thicknesses is compared and analyzed. In addition, the blasting effect is optimized by the principle of “sub-regions and stages”. For weak frozen soil, the blasting effect can be improved with shorter stemming length and longer charge length. For strong frozen soil area, auxiliary holes are added around the main blasting holes to reduce the boulder yield. Furthermore, the optimization scheme of blasting parameters which is suitable for the change of frozen soil layer thickness in Alpine region is summarized. As a result, the blasting effect is significantly improved, which greatly reduces the boulder yield after blasting of the frozen soil layer and improves the ore supply rate.

Prefabricated piers are widely used in the field of bridge construction and are often affected by accidental explosions or terrorist attacks. In order to study the influence law of the damage factors of prefabricated bridge piers under explosion load, a numerical model of the prefabricated bridge piers under near-field explosion load has been established by ANSYS. Based on the residual bearing capacity of bridge piers, the damage parameter D is proposed as the anti-explosion index. The influence of five damage factors, including the explosive equivalent, the distance from the explosion center, the initial prestress, the number of segments and the setting of shear keys, on the damage degree of bridge piers is analyzed. On this basis, grey correlation analysis method is used to measure the degrees of correlation and contribution among the damage factors. The results show that the comprehensive reduction rates of failure parameter D are 32.1% and 29.6% by increasing the initial prestress and setting shear keys between segments, which can effectively reduce the damage of the piers and have a good correlation with the blast resistance of prefabricated piers. However, increasing the shear key height and segment number to 12% and 7.2% has a small effect on pier damage. The order from largest to smallest of the five factors in the correlation degree on the damage of the fabricated bridge piers under blast loading is: TNT equivalent, blast center distance, initial tensile prestress, shear key setting and segment number. In the anti-explosion design of prefabricated bridge piers, the factors of large correlations such as increasing the initial tensile prestress and setting shear keys can be given priority. The grey correlation analysis method has certain reference value for the analysis of damage factors of prefabricated bridge piers under explosive load.

In order to study the crushing energy dissipation characteristics of graphite ore rock under impact loads, ϕ 50 mm diameter split Hopkinson pressure bar (SHPB) test device is used to conduct impact compression tests. The crushing energy dissipation law of the graphite ore rock samples is analyzed under different loading rates with five different impact pressures from 0.2 MPa to 0.6 MPa with a 0.1 MPa interval. The test results show that the dynamic compressive strength of the samples have a strong third-order polynomial relationship with the average strain rate under impact loads. The graphite ore rock has dynamic hardening under impact loads, and its dynamic compressive strength increases nonlinearly with the increase of strain rate, which shows an obvious strain rate effect. In addition, there is an obvious logarithmic relationship between the crushing dissipation energy and the incident energy. With the increase of incident energy, the crushing dissipation energy also increases. However, the proportion of the crushing energy gradually decreases from 0.38 to 0.11. The crushing energy dissipation density of the samples has an obvious strain rate effect, and its value increases with the increase of strain rate. Besides, the average particle size of the broken samples is strongly correlated with the energy dissipation density of the samples. As the energy dissipation density increases, the crushing degree of the sample becomes more severe. Therefore, the average particle size of the crushing fragments can be used to quantitatively describe the crushing degree of the samples.

The blasting fragment size of a mine is required to be less than 0.4 m. However, this area has a geological structure consisting of both hard and soft layers, which makes the traditional blasting method easy to produce boulders, and the blasting quality difficult to meet the requirements. In order to conquer the problem and save the construction cost, blasting tests on square hole layout with both deep and shallow holes were carried out with the middle shallow hole depths of 0 m, 4 m, 5 m, 6 m and 7 m. Firstly, ANSYS/LS-DYNA finite element software was used to carry out numerical simulations with a limestone model with RHT constitutive relation in the upper part and a marl model with HJC constitutive relation in the lower part, forming a hard-soft interlayer structure. Then, numerical tests were conducted to initially obtain more optimal middle hole depths, and the distribution characteristics of rock mass damage and the distribution law of blast effective stress under different test conditions were analyzed. Since ANSYS/LS-DYNA does not take the effect of detonation gas into account, the middle shallow hole depths of 4 m and 5 m were selected for on-site blast tests in order to obtain more accurate experimental conclusions and not to excessively increase explosive consumption. The research results show that it is effective to reduce the blasting boulder yield by square hole layout combining deep and shallow holes. When the depth of the middle shallow hole is 5m, the curvature coefficient Cc and the boulder yield can be reduced. Before the technology optimization, the average boulder yield was about 64.4%, and the rate of fragments larger than 0.4m have been reduced to about 38.1% after the technology improvement, making the blast fragmentation to a favorable level. So, the scheme of 5 m shallow holes has a better effect of reducing boulder yield than the original blasting scheme and the scheme of 4 m middle shallow hole.

In order to select the shaped charge structure with low residual height and small fragmentation after blasting of concrete base, numerical simulation method is used to study the motion characteristics of jet flows formed by 60° and 120° conical liners and explosive formed projectiles (EFP) formed by curved liners with curvature radius of 10.8 cm as well as the vertical penetration process and damage effect on concrete bases under the same explosive charge, outer diameter and shaped charge liner thickness. The results show that: Different shaped charge penetrators have different penetration modes to concrete bases. The head part of the jet flow formed by the 60° conical liner penetrates the concrete base first, and then the pestle part expands the hole. For the 120° conical liner, the pestle body and the jet flow penetrate the concrete base together, while the curved liner mainly penetrates the concrete base by the formed projectile; the crushing capacity of the shaped charge is related to the diameter of penetration hole. The larger the hole diameter is, the stronger the crushing capacity is. The penetration hole diameters of 60° liner, 120° liner and EFP liner are 4.3 cm, 5.2 cm and 7.0 cm, respectively. In addition, the number and width of cracks formed within the penetration depth show an increasing trend; the residual height of the concrete base after blasting is related to the distance between the transverse through cracks and the bottom, while the formation of transverse cracks is related to multiple factors such as penetrator parameters, charge quantity and so on; for the concrete base with a limited size, a shaped charge liner with a large cone angle has a better comprehensive effect with respect to crushing range and degree. Although the penetration ability of EFP liner is the weakest and the residual height of the concrete base after blasting is large, its crushing ability within the penetration depth is the strongest. The study of blasting effect of different shaped charge penetrators on a concrete base can provide a reference for exploring damage mechanism and selecting destruction mode.

As a discontinuous and anisotropic heterogeneous structure, rock mass is randomly distributed with joints, cracks, faults and other structural planes. The existence of structural planes has an important influence on blasting effect. In order to explore the influence of the angles and locations of structural planes on bench blasting effect, LS-Dyna numerical simulation and field experiments were conducted based on Beskuduk open pit coal mine. The numerical simulation results show that when the dip of the structural plane is less than 30 degrees, the peak stress is less affected. When the dip of the structural plane is greater than 30 degrees, the initial peak value of the explosion stress wave increases with the increase of the angle. In addition, the position of a weak interlayer in a bench affects the energy release. Compared to the situation that the weak interlayers are located in the upper area of the bench, the blasting effect when the weak interlayers are located in the middle and lower areas, the energy release is more obvious with a worse blasting effect, therefore a specific blast method is needed to solve the problem. The field practice shows that with the increase of the structural plane angle, the boulder yield presents a decreasing trend. For the situation that the weak interlayers are located in the middle and lower part of the bench, the method of increasing the subdrilling to 0.5 m and adding 3~5 m depth to the inclined holes can effectively reduce the boulder yield, improve the blasting effect and the shovel loading efficiency.

Understanding the classification of rock mass blastability is an important basis for determining reasonable blasting parameters and improving engineering efficiency. Combined with the practice of bench blasting in Weijiamao mining area, the protodyakonov coefficient and the tensile strength of rock samples are obtained according to the engineering geological data of the mining area, on the basis of site investigation and sampling. The density and acoustic wave velocity of the rock samples on the exposed step surface are measured and analyzed by wax sealing density tests and acoustic wave tests. According to the four indexes obtained, the rock mass blastability in the mining area is studied based on the principle of weighted cluster analysis. The research shows that there are coarse sandstone, medium sandstone, fine sandstone, sandy conglomerate and argillaceous sandstone in the Wejiamao mining area. The density of the marl sandstone is the highest, which is 2.75 g/cm³. The density of the coarse sandstone is the lowest, 2.01 g/cm³, while the density of the sandy conglomerate, fine sandstone and medium sandstone lies between the marl sandstone and the coarse sandstone. In the acoustic wave test, the longitudinal wave velocity of the rock in the 1064 platform is the highest, which is 2.615 km/s, while that in the 1096 platform is the lowest, which is 2.029 km/s. According to the distribution of the rock samples at the corresponding platform, the blastability of the rock mass in Weijiamao mining area gradually decreases from 1112 platform to 1064 platform. Among them, the 1112 platform is mainly sandy conglomerate with a medium blastability. The 1096 platform is mainly coarse sandstone with an easy blastability. The 1080 platform is medium sandstone with a medium blastability. The 1064 platform is mainly composed of fine sandstone with a difficult blastability.

A waste fireworks and firecrackers destruction project in Nantong city required the destruction process to be safe and efficient. On the basis of fully understanding the characteristics of the fireworks and firecrackers to be destroyed, the principles of destruction were clarified, and the destruction plan was carefully designed in combination with the specific characteristics of the project. In the open offshore area, a 20 m×20 m site with a depth of 2 m and a maintenance slope of about 5 m was first pre-set as the destruction site. The entering and exiting roads were then arranged reasonably so as to improve the unloading efficiency. According to the traffic conditions between the storage and the destruction site, the transportation route and time were determined. At the same time, in order to ensure the safety of the transportation process, the vehicle speed, loading and unloading, placing and other technical requirements were strictly regulated. According to the size of the destruction site and the location of fireworks to be destroyed, the minimum discharge angle was calculated as 12°. Combined with the maximum height of the fireworks liftoff, the discharge area, escape area and scattered area were determined in the process of destruction, based on which the safety warning range of the destruction was set as 120 m. The joint control measures of warning personnel and UAV were adopted to monitor the destruction process in real time to ensure that the fire hazard was controlled in the initial stage. The destruction was thorough, safe and accident-free with good results.

Field tests of blast vibrations were conducted based on the concept of interference between blast-induced seismic waves for the purpose of reducing blasting vibration intensity and controlling blasting vibration hazards. Three different blast schemes were realized by using electronic detonators, and nonel detonators were used for the fourth blast scheme as comparison. Monitoring points were arranged at the locations of 15 m, 30 m, 45 m and 60 m away from the working face. By studying variation law of the blasting vibration velocity, the optimal delay intervals between holes and rows were selected as those of the third scheme based on the characteristics of accurate timing of electronic detonators. In the third scheme, the cut holes were initiated every two holes from top to bottom with an inter-hole delay of 8 ms. The slashing holes were arranged symmetrically along the center of the working face, and initiated hole by hole with an inter-hole delay of 16 ms and inter-row delay of 100 ms. In addition, the roof holes and bottom holes were initiated with a delay interval of 100ms. This scheme was used to obtain a vibration reduction effect by wave destruction interference. The test results show that the blast parameters are the key to reduce the blast vibration intensity. With the same distance to the blast source, the peak particle velocity when electronic detonators are used is much smaller than that when nonel detonators are used. At the same time, the dominant frequency of electronic detonators is higher than that of the nonel detonators. This engineering technology has achieved significant vibration reduction effect in the blasting construction of the flood discharge tunnel of Luoning pumped-storage power station in Henan Province.

In order to analyze the dynamic response of the shield segments during the blasting excavation of a connecting channel, on-site vibration monitoring has been conducted based on the shield interval project of Qingdao Metro Line 8. The measured blasting vibration data show that the cut holes have the strongest impact on the shield segment vibrations. Then, based on the on-site charge of the cut holes, the MIDAS-GTS NX simulation software is used to establish a three-dimensional model to analyze the vibrations and stresses of the shield segments with 8 different blasting distances from the exit and entry of the connecting channel. Compared with the entry blasting, the impact of the exit blasting on the vibrations of the adjacent shield tunnel is more intense under the same blasting distance, and the peak vibration velocity is 2.9~3.4 times that of the entry blasting. On the other hand, the growing rate of the peak vibration velocity also increases with the decrease of the distance. When the allowable vibration velocity is 20 cm·s^-1, the blasting distance should be greater than 5.0 m at the exit and greater than 1.25 m at the entry. The rocks that have not been excavated are excavated with non-blasting methods. The stress concentration is the most obvious in the opening segments, but the position where the maximum principal stress is generated shifts from the bottom of the rectangular opening through the intersection of transverse and longitudinal seams on the side of the rectangular opening to the top corners of both sides of the upper part of the rectangular opening with the decrease of spacing. Cutting the segments at the intersection of the connecting channel and the shield tunnel will form an incomplete opening structure, which will weaken the maximum principal stress on its inner side under the blasting load, but will cause a small range of stress concentration on its outer side, making it the weakest position of the shield tunnel lining structure.