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.

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.

There was a special working face with an ultra-high bench and a large resistance at the 410 platform of a mine in Qingyuan city, which required one-time blasting. This working face had a bench height of 30m, a length of 80 m, and a face angle of 45°~80°. Due to the large bench height, small face angle, and the different face angles of the upper and lower parts, it was difficult to conduct the blasting construction. Before blasting design, the RTK measuring instrument and total station were used to measure the topography of the detailed working face, and then calculate the slope angle of each position of the face according to the topographic map. According to the rock properties, the construction experience and the drilling rig type, the powder factor and blast hole diameter were determined. Based on the above results, the toe burden, drilling angle, depth and spacing of the first row of blast holes were then deigned. Similarly, the burden, drilling angle, depth, spacing of the following rows of holes were also determined. After the hole parameters were determined, the charging structure was designed according to the burden of each row of holes, the rock volume of each hole, powder factor, and the principle of uniform blasting action. Finally, the initiation network was designed by the software of 3Dmine based on the direction of rock movement and the earthquake-proof requirements of the protected objects. During the construction process, the key links such as hole layout, hole depth measurement, drilling, charging, and network connection were strictly controlled, and positive results were obtained after blasting.

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.

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.

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.

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.

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.

To reveal the propagation characteristics of blasting vibrations induced by blasting demolition of a reinforced concrete support beam in a deep foundation support system, the vibration velocities and frequencies in the horizontal and vertical directions of the support system and the response spectrum characteristic of the enclosure structure of the foundation pit are analyzed based on the monitored vibration data. The vibration test lines were laid in the same and the upper layer to the support beam. The results show that the vibration velocity decays rapidly with the increase of distance. The peak vibration velocity at the blasting layer is 5~7 times than that of the upper layer within 50 m of the blasting area. However, the peak vibration velocity of the blasting layer gradually attenuates to 1~2 times than that of the upper layer outside 50 m of blasting area. Besides, there are obvious differences among the components of vibration velocities in three directions in the blasting layer. The radial component has the largest peak value, which is 2~5 times of the vertical component. On the contrary, the three components of vibration velocities in the non-blasting layer are close to each other. Meanwhile, it is high frequency vibration in the support beam, and the vibration frequency of the blasting layer is slightly smaller than that of the non-blasting layer, and both of them have a steep increase phenomenon in the supporting structure of the foundation pit. When the support beam is demolished by blasting, the short-period response spectrum of the enclosure structure of the foundation pit is obviously beyond the designed spectrum, and the blasting vibrations will have a certain influence on the enclosure structure. The related results can provide references for the design of blasting demolition of support beams, vibration control, and the dynamic response analysis of enclosure structure of a deep foundation pit.

In order to realize the blasting demolition of 62.8 m high brick structure chimney in complex environment, various demolition options which fully consider the structure of the chimney and the surrounding environment were compared in the case of insufficient space for collapse on the east, west and north sides. After analysis, one-way and two-way folding blasting options were initially selected to blast and demolish the chimney. The circular angle of the upper and lower notch was designed as 220°. The lower notch was set as 2 m high at 0.5 m from the bottom of the chimney, while 30 m from the bottom of the chimney located the upper notch which parameters need to be simulated and optimized. ANSYS/LS-DYNA finite element analysis software was used to compare the collapse effect of the preliminary scheme, and it was calculated that the one-way folding blasting did not meet the demolition requirements, so the two-way folding blasting was selected. Then the chimney collapse process was simulated with the upper cut height of 1m, 1.5 m and 2 m and the delay times of 0.5 s, 1 s, 1.5 s, 2 s and 2.5 s between the upper and the lower cut. After analyzing the collapse process and the distribution range of the blast pile of the chimney under different working conditions, it was determined that the best folding effect with a small collapse space happened when the upper cut height was 1m and the delay time was 1 s. Furthermore, safety measures which were related to blasting vibration and flyrock protection were designed. The blasting effect showed that the chimney collapsed smoothly according to the designed direction during the blasting process, and no damage occurred to the surrounding buildings (structures). The overall blasting demolition effect was good enough to meet the expected goal. It can provide a reference for related scholars and demolition projects.