During open-pit bench blasting, the movement trajectory of rock in the bench area is an important factor affecting the accurate mining of open-pit mines, especially for unevenly mineralized ore bodies. In order to solve the difficult problem that the internal movement trajectory of rock during bench blasting in the Wushan Cu-Mo mine is not clear, a tracking algorithm with signal markers was used on bench blasting tests at the Wushan Cu-Mo mine in Manzhouli. Through on-site installation, positioning, monitoring and data analysis of intelligent beacons, the research results showed that: the first row of beacons had a long motion time and fast movement with an average speed of 5.89.8 m/s. The movement distance was between 18.4 m and 29.4 m. Due to constraints and obstruction of the rock mass in the front section of the bench, the motion time, movement speed and distance of the#2 monitoring beacon were significantly reduced, with an average speed of 1.8~4.8 m/s and a movement distance of 5.3~14.2 m. The movement distance and time of the#3 blast hole beacon was the smallest, and the inclination angle of the#3-3 beacon reached about 25°. The inclination angles of#6-1, #6-2 and#6-3 beacons were relatively gentle at about 2°~8°. From the depth perspective, the shallow beacons move forward horizontally during the forward rush period, and there was a significant downward trend in the latter half. The vertical motion distance of the deep beacons was significantly smaller than that of the shallow beacons.

In order to control the forming effect of excavation profile and reduce the disturbance of preserving rock mass caused by blasting, the foundation pit blasting at the Yunnan bank of the large arch bridge across Jinsha river, whose total depth is about 51 m and one-time excavation depth is about 20 m, is taken as the engineering background. Reinforced loose blasting with hole-by-hole initiation was applied to the main blasting holes and smooth blasting was used for the contour holes. A kind of deep hole smooth blasting technology which can be applied to foundation pit excavation of the deep and steep arch bridge is presented. In addition, the action process of gas, the expansion pressure at the hole wall and the damage range of the smooth blasting hole were theoretically calculated and analyzed. The blasting results show that a flat excavation profile, with more than 90% half-hole ratio of relatively intact rock mass and less reserved hole marks of relatively cracked rock mass whose overbreak and underbreak can still be controlled, can be formed by using the deep hole smooth blasting technology, which greatly reduces the stress concentration on the rock wall surface. The crushing zone will not be formed near the charge section in the smooth blasting and the maximum damage range of the reserved rock mass was about 49cm, which fully ensured the rock wall stability and construction safety. In the process of smooth blasting construction, engineering measures were also taken to ensure the reliability, safety and economy, including slowly tilting the excavation surface at the bottom of the bench to the free surface, tying the explosive charge with cotton rope for traction, and setting detonators inside and outside the hole every 5~7 smooth blast holes.

As the main index to evaluate the blasting effect, the rock blasting fragmentation directly affects the subsequent construction objectives and construction costs of water conservancy and hydropower projects. In the process of quarry blasting, it is of great significance to improve the blasting efficiency and quality and meet the demand of good grading curve for the dam aggregates in the construction of water conservancy and hydropower projects. The influence of the number of free surfaces and the delay interval between holes on the rock blasting effect is studied by establishing a two-dimensional finite element numerical model. Firstly, the interaction of stress waves between holes and the reflection mechanism of explosion stress waves on free surfaces are explained theoretically. The conditions for the generation of blasting cracks are also analyzed. Then, with the help of ANSYS/LS-DYNA finite element software, RHT model is used to simulate the rock fracture process under different number of free surfaces and different delay times between holes, and WipFrag is used to analyze the rock grading under different blasting conditions. The numerical simulation results show that the influence of different number of free surfaces on blasting grading is obvious. Compared with no free surfaces, the maximum bulk yields of single free surface, two free surfaces and three free surfaces decreases by 25.9%, 46.5% and 61.8%, respectively. It can be seen that the more the number of free surfaces, the more cracks produced in the rock, the better the blasting fragmentation effect. Compared with simultaneous initiation, delayed blasting is beneficial to improve the rock fragmentation effect, but the interaction between stress waves and holes is not obvious in short delayed blasting.

With the widespread use of mixed emulsion explosives, there exists the situation that the stemming materials penetrate into emulsion explosives in open-pit blasting construction, which indirectly changes the stemming length and reduces the blasting effect. To study the influence of stemming on mixed emulsion explosives, stemming simulation tests, numerical simulation tests and field blasting tests were carried out successively. Firstly, four kinds of PVC pipes with common hole diameters were used to simulate the blasting holes, and the rock chips were used to simulate the stemming materials. They were used to systematically study the infiltration of rock chips into the explosives on top of the explosive column during the filling process of stemming. Secondly, the numerical simulations of single-hole blasting were conducted with the LS-DYNA software, and the influence of the stemming mixture at the top of the explosive column on the explosive power was investigated by observing the changes of stress values at the measurement points. Finally, the stemming filling process was improved by setting physical isolation during the charging process based on the bench blasting in the Jinduicheng open pit mine. And the effect of stemming on the mixed emulsion was analyzed by comparing the blasting effect before and after the physical isolation. The results show that the phenomenon of explosive overflow appears on the top of the explosive column in the explosive charging process. Then, the rock chips gradually infiltrate into the emulsion explosive due to the influence of gravity after the charging is completed, and the infiltration length of rock chips increases with the increase of hole diameter in the same time. The numerical simulation results show that the stresses of different monitoring points have decreased, and the infiltration of stemming reduces the explosive power of the top explosive. The fragmentation analysis of the top rock after improvements shows that the main fragment size distribution of rocks decreases from 20~40 cm to 0~20 cm, and the proportion of rocks over 60 cm decrease from 6.13% to 1.81%, compared with the conventional charging process. In summary, the stemming has a significant impact on the power of emulsion explosive and blasting effect, and it can effectively improve the blasting effect by taking physical isolation to separate the stemming and explosive.

In the field of blasting work, stemming has a significant impact on the effectiveness and safety of blasting operations. To improve the blasting effect and reduce blasting costs, it is essential to determine the optimal length of stemming. This study uses a combination of explosion wave theory, theoretical mechanics, and LS-DYNA numerical simulation to analyze the impact of stemming length on blasting effect, which is then validated through field experiments. The study results indicate that when the blast hole depth is between 0.6 m and 1.4 m, the optimal stemming ratio is between 0.38 and 0.54, and with an increase in blast hole depth, the optimal ratio decreases. When the blast hole depth is between 1.6 m and 2.4 m, the optimal stemming ratio is between 0.36 and 0.38. If the blast hole depth exceeds 1.2 m, and the stemming length equals or exceeds half of the blast hole depth, a detrimental effect may occur. The radial uncoupling coefficient R exerts a significant effect on the optimal stemming length. When R is less than or equal to 1.8, the optimal stemming length decreases with an increase in R. However, when R is greater than 1.8, the optimal stemming length remains unchanged. Additionally, field experiments were conducted at the Wangcun Coal Mine Limited Liability Company 8107 return airway, including tests on 1.2 m and 2.2 m cut holes and a 2.0 m auxiliary hole. The optimal stemming lengths were found to be 50 cm, 90 cm, and 80 cm, respectively, which aligns with the results of theoretical calculation and numerical simulation.

A combined demolition method of directional tilting of main tower and in-situ collapse of bridge beam has been designed for the blasting demolition of a single-tower reinforced concrete cable-stayed bridge in complex environment. An "inverted step" cut with a height of 4 m was designed for the middle tower pillar, and the mechanical pre-processing method was used in the lower tower pillar to form two windows with a width of 1.3 m and a height of 4 m to reduce its strength. The loose blasting was used for the bridge beam at four locations where the cables were anchored on the beam. Decked charge was adopted for the blast holes deeper than 2.1 m and initiated by detonating cords, which effectively dispersed the explosive energy. The middle tower pillar, lower tower pillar and the beam were initiated as 3 stages with nonel detonators. A “rigid + flexible” composite protection method was proposed for the culvert crossing the bridge. Two sandbag damping walls were settled on the touchdown area of the bridge beam to form a "flexible" protection. Meanwhile, a welded steel skeleton and rubber cushion layer were arranged along the direction of the culvert to form the “rigid” protection. Grass curtains, bamboo fences, and steel wire layers were covered on the blasting area. After the blast, the tower toppled on the predetermined direction. And the main beam collapsed in place, divided into several sections which were then processed with mechanical methods. In this project, good blasting results have been achieved without causing flyrock accidents or impact damage to the culvert.

In order to successfully demolish a high pier reinforced concrete aqueduct by blasting between the 75^#~84^# piers of Dongfeng Canal in Yichang City and reduce the impact on the surrounding complex environment, a bidirectional collapse design was adopted. In the design scheme, the aqueducts between the 75^#~76^# piers collapse in a northerly direction perpendicular to the aqueduct trend, and the aqueducts 77^#~84^# piers collapse westward along the aqueduct trend. More precisely, an initiation network of electronic and non-electric detonators with delays of 50 ms and 150 ms was adopted using the 75^# pier as the initiation point. Moreover, the harmful effects of blasting on the environment were controlled by using lifting holes as blast holes, excavating vibration reduction ditches, hanging nets and covering protection layer, storing water in the trench body, and covering soil protection. The results show that the aqueduct collapsed with a 4-minute delay after initiation, and the collapsed pier body was basically decomposed into blocks with intact aqueduct body, with most fragments scattered along the trend within 10 m of the central axis of the aqueduct, and only a few small pieces flying farther than 10 m. The adopted protective measures can effectively control the blasting flying rocks and vibration, and no damage has been found to the inverted siphon of temporary water delivery pipeline and the road pavement. The project was carried out successfully despite the delay in collapse. The possible reasons for the delayed collapse include no incision on outside of the structural column, the delay time interval between pier columns is small, and the blasting incision is small.

A 110 m thin wall reinforced concrete cooling tower has been demolished by controlled blasting. Aiming at the characteristics of large height, thin wall and large bottom diameter of the cooling tower, the blasting scheme of “opening window, breaking steel bar and reserving supporting plate” was adopted. In the pre-demolition process, two simplified directional windows were set up along the edge of the blasting zone by optimizing the blasting incision of the cooling tower. In the blasting area, only the bottom and top of the herringbone column of the cooling tower were blasted, and the blasting incision was divided into 5 blasting areas using the non-electric millisecond delay initiation technology. In order to control the damage effect of blasting, laying buffer soil layer and steel plate in the collapse direction of the cooling tower for double protection effectively reduced the collapse touch vibration. The protective measures combined with mesh and geogrid covering at the blasting incision effectively controlled the flying stones without causing damage to the surrounding structures. The blasting effect shows that setting two simplified directional windows on the edge of the blasting incision not only cuts down the drilling and related workload, reduces the safety hazard and the difficulty of protection, but also improves the structural stability of the pre-treatment part and prevents the blasting incision from falling. Through the simplified design of the directional window, the cooling tower distorts and disintegrates fully in the collapse process, with a concentrated explosion pile and small ground vibration.

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.

The charge parameters are crucial factors affecting the damage effect of RC components under close-in explosion. The study of the influence law of different charge parameters on component damage is of guiding significance for improving warhead design and optimizing fire strike scheme. A cylindrical charge with a length to diameter ratio of 5.5 and a charge of 10 kg was used to carry out near explosion damage tests of the supporting column of a reinforced concrete single-storey stacked structure plant at a proportional distance of , and a comparison test of spherical charge was set up. The experimental results show that the damage effect of a cylindrical charge is stronger than that of a spherical charge, and the reliability of the numerical simulation model is verified by the experimental data. The length to diameter ratio, blast height, charge amount and action distance of cylindrical charge are taken as the research factors, and three levels are determined for each factor. The simulation results of blast damage of reinforced concrete under 9 different charging parameters were designed and obtained by orthogonal simulation test method, and the influence law of cylindrical charging parameters on the damage effect of reinforced concrete columns was analyzed. The amount of the cylindrical charge has the greatest effect on the damage degree, the ratio of length to diameter has the second effect, and the blast height has the least effect on the damage degree. When 4.5≤L/D≤6.5, the damage effect on the component is greater. When the blast height is 1/4, 1/2 and 3/4 column height respectively, the explosion at the 1/4 column height has the best damage effect on the support column.