In order to study the blasting technology of the in-situ collapse of a cooling tower, the incision was analyzed by finite element software. Furthermore, a high-definition camera was used to collect the deformation data of the cylinder body and lambdoid stand columns. Then detailed analysis was carried out for the deformation time of the cylinder, the collapse speed, the change of the incision closure, and the collapse range after the distortion and deformation of the cylinder. The practice results show that the incisions for the in-situ collapse of the cooling tower cannot be designed as four equal parts as convention. It is easy for four equally distributed parts to cause the bottom part not to collapse. The perimeter of the fourth area (the last initiated part) is slightly larger than that of the first area by a quarter. The in-hole delay times in the four areas are MS4, MS8, MS8 and HS3, respectively, and the out-hole delay time is MS2. Through the finite element simulation, it takes 1 second to generate the collapse trend of the cylinder, 3 seconds to close the incisions of the cylinder, and 6.8 s for the cylinder to squeeze, twist in the air and touch the ground. The deformation of each area must be completed within a reasonable time. By image analysis and calculation after the explosion, the above simulated times are the same as the actual times.90% of the in-situ collapsed cylinder is within the pool, and the upper ring beam is thrown out of the pool by about 6 meters, which does not affect the surrounding hydrogen production station, circulating water pump room, steel gate and other facilities. After measurement, the peak vibration velocity the natural gas pipe is only 2.095 cm/s, indicating no impact on the buried gas pipe 23 meters away. The research shows that the in-situ collapse blasting technology can effectively control the collapse touch-down vibrations and the collapse throw distance of the cylinder.

Nayong Weima stone arch bridge and the new simply supported beam bridge have a 41° diagonal crossing in the horizontal direction, with a total length of 68 m. It passes 28.5 m below the fifth span of the new bridge, and is only 0.8 m away from the #4 column of the new bridge. In order to ensure the successful blasting demolition of the old stone arch bridge, the in-situ buffer collapse control blasting technology is adopted to ensure the safety of the adjacent new bridge. Considering the damage to the surrounding environment caused by the blasting demolition of the stone arch bridge, especially the damage to 4# column and the pier foundation, the horn blasting notches is used based on the structural characteristics of the stone arch bridge and the analysis of blasting and collapse vibrations. At the same time, the blasting notch of the East-West arch foot is moved to the second abdominal arch, and the crushing notch close to #4 column is added. For the initiation network, the sequence of "west to east and south to north" is adopted. Other methods include adjusting the resistance line of the blast hole close to the #4 column and taking different powder factors for different blasting notches, etc. All those measures are taken to make the stone arch bridge tends to collapse to the south with a minimum collapse size and reduce the impact of blasting on the surrounding environment. Furthermore, the reliability and safety of the blasting demolition of the stone arch bridge are ensured by the safety protection measures such as stacking of slag and soft soil to cushion dikes and setting up protective shelving. According to the collapse vibration formula, the vibration velocity of the bridge deck corresponding to the #4 column of the new bridge is calculated to be 3.9~5.2 cm/s, which is close to the maximum vibration velocity of 3.879 cm/s measured by the vibration meter. It is verified that the design idea of the blasting demolition of the stone arch bridge and the selection of the relevant parameters are scientific and reasonable. The blasting demolition has achieved ideal results, which could provide reference for similar blasting demolition projects.

Rock foundation excavation plays an important role in the entire project of hydraulic structures. The key and difficult point of the blasting excavation is how to reduce the damage of the rock mass on the foundation surface under the premise of ensuring the excavation of the structural foundation to the specified elevation. In this paper, ANSYS/LS-DYNA finite element software is used to numerically simulate the blasting damage of the rock mass 40 m underwater. The blasting and excavation simulation of composite energy dissipation structure, flexible cushion and traditional charge structure is carried out in a 24.5 cm×24.5 cm×30 cm rock mass model, respectively. Fluid-structure coupling algorithm is used in the simulation process, and 0.4 MPa water pressure is added to simulate the 40 m water depth environment. The simulation results found that the damage depth of the basement, the energy transfer of the retained bedrock and the damage degree of the retained bedrock can be reduced by 38.89%, 30.52%, and 30.90% respectively by using the composite energy dispassion blasting technology under the same conditions. The results also show that the energy dissipation structure can effectively control the damage form and scope of the rock mass retained on the foundation surface, which can be applied to the protection of foundation surface of underwater rock excavation.

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.

The stability calculation is the key to prevent and control the geological disaster of dangerous rock collapse, which is of great practical and prediction significance. However, the quasi-static method cannot depict the influence of factors as the shape and geometric size of the dangerous rock mass, the frequency and initial phase on the actual blasting vibration load. Based on conventional pseudo-static analysis and the slice method, a blasting dynamic stability analysis method considering size effect is established. This calculation program is compiled by using MATLAB. The results indicate that the calculated minimum stability coefficients of dangerous rock mass vary periodically with the initial phase of the blasting seismic waves. For a given calculation with specific parameters, the coefficients are proximate to those calculated by conventional quasi-static analysis. The relative difference of these two calculations is between 5.1% and 8.2%, which indicates the calculation method and program are reasonable and effective. When the number of slices is 1, the calculated results of the program are equivalent to those calculated by traditional quasi-static method. The method proposed in this study provides a reference for dynamic stability analysis and evaluation for dangerous rock mass.

Field detection of surrounding rock damage range is cumbersome. In order to obtain the surrounding rock damage range simply and accurately, a major underground cavern project to be built is taken as the research background. Theoretical analysis and numerical simulation are adopted according to the blasting design scheme to establish the cumulative damage calculation model of multi-stage delay blasting with different charges. By using equivalent blasting load method and LS-DYNA complete restart technology, the blasting vibration data and the cumulative damage range of surrounding rock under multi-stage delay blasting loads are obtained. The cumulative damage effect of surrounding rock of the underground cavern is analyzed and the correlation between blasting vibrations and the cumulative damage range of surrounding rock is studied. The results show that the induced damage of surrounding rock of the underground cavern is mainly caused by blasting of the second circle holes and the surrounding hole, and the damage range of surrounding rock of the cavern vault (2.21 m) is significantly larger than that of the surrounding rock of the arch waist (2.05 m). The peak value of the blasting vibration curve is within the delay time range of cutting holes, which is not consistent with the blasting stage that causes the damage of surrounding rock. Therefore, the correlation between the peak particle vibration velocity and the damage range of the surrounding rock should be studied within the delay time which has great influence on the damage of surrounding rock. The quantitative relationship between the cumulative damage range of surrounding rock and blasting charge, blasting center distance and peak particle vibration velocity is established, and the functional relationship between the cumulative damage range of surrounding rock can be deduced from the peak particle vibration velocity at any blasting center distance. It provides a basis for controlling the blasting damage of surrounding rock and has practical significance for guiding the safety of blasting construction on site.

In order to study the influence of blasting vibration on the stability of permanent slopes in an open-pit mine, this paper takes three pits in the Kamoya-Kazibizi mine as the research object, and compares the effects of blasting vibrations on the stability of the slopes with different rock characteristics. By collating the measured blasting vibration data, the maximum charge per delay and the distances from the measuring points to the center of the blast source, the blast vibration attenuation law and curve are obtained by regression analysis with a power function, which can be used to predict future blasting vibrations. In order to obtain the influence of the distance from the measuring point to the center of the blast source and the maximum charge per delay on the vibration velocity, the distance and charge are taken as the influence factor, and the blasting vibration velocity is taken as the dependent variable. Based on the vibration velocity calculated according to the fitted blasting vibration formula of each pit, nine groups of experimental schemes are designed. Using SPSS software to carry out variance analysis, it is concluded that the distance between the measuring point and the center of the blast source is highly sensitive to the blasting vibration velocity, and has a greater impact on the mine slope vibration. Therefore, for the soft rock slopes of Kazibizi mine and East No.2 mine, 2~3 rows of holes are reserved as a non-blasting area, and mechanical excavation is used to trim the slopes. For the medium hard rock slope of South No.2 mine, pre-split blasting is used to reduce the impact of blasting vibration on the slope stability. The research results have reference and application value for other open-pit copper-cobalt mines in Congo.

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.

The dynamic response of the lining structure of an existing tunnel during the blasting construction of a new tunnel is studied based on the Bogongao No.1 tunnel project which belongs to one of the level 1 risk tunnels of Ganzhou-Shenzhen high-speed railway. The numerical model of the test section is established by using ANSYS/LSDYNA finite element software. By comparing the field measured with the model calculated vibration velocities, the reliability of the numerical simulation is verified with the inversed surrounding rock mass parameters. Furthermore, based on the parameters of the test section, a numerical model of the intersection of the two tunnels is further constructed, which is used to analyze the vibration attenuation law of the existing tunnel lining structure in the intersection, and put forward vibration reduction measures under the worst cases at the intersection. According to the research results, the largest vibration velocity appears at the vault of the existing tunnel and the smallest vibration velocity is at the floor. Within 30 m from the front and back of the intersection, the vibration velocity at the vault is about 2.0~2.3 times that at the side wall closer to the blast. For the whole section of the existing tunnel, the controlled vibration velocity of 1.6 cm/s. However, for the side wall, the early warning value of vibration velocity should be 0.8 cm/s. When the cut holes are bottom initiated, most of the explosion energy is transmitted to the unexcavated area, which contributes to a higher attenuation rate of vibration velocity from the excavated area of the new tunnel than from the unexcavated area. The blasting scheme of the test section is no longer applicable to the cross affected section. On the premise of considering both the work efficiency and blasting effect, the vibration velocity of the secondary lining in the existing tunnel can be controlled within the safe range after the footage is shortened to 1.0 m and the cut hole charge is reduced to 9.86 kg.

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.