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 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.

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.

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.

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.

In-situ collapse blasting demolition technology is a new blasting demolition technology which can break through the condition of serious shortage of collapse space for towering chimneys. The difficulty of this technology is to set up efficient operation platforms at multiple locations at hundreds of meters to quickly complete drilling, charging, stemming and networking, thus forming multiple ring blasting cuts. According to the requirements, a variable diameter hanging basket as a construction platform is developed. The overall design idea of the new operation platform is as follows: The core function of the platform is defined based on the analysis of the operation process, and the variable section basket platform with a sliding plate is selected by comprehensively considering various factors such as efficiency, reliability, adaptability and cost. A parametric model is established to determine the optimal values of the length and included angle of the fixed section and the sliding plate of the hanging basket for different chimney dimensions, which is according to the adaptability of the platform to the overall dimension of the chimney. The technical schemes of the telescopic structure are compared and selected, and finally the steel wire rope traction scheme together with the resistance reduction scheme by tetrafluoroethylene plate is selected. On the basis of the above technical scheme, the structural scheme, safety guarantee scheme, adaptive design scheme, installation, disassembly and using scheme of the platform are determined. In order to verify the reliability of the structural design, the stress analysis of the structure under various working conditions is carried out by using the finite element software. Meanwhile, a special test frame is set up, and a series of tests including functional test, load test and reliability test are carried out on the first test prototype to verify the safety and functional reliability of the platform structure. The test results show that all the functions of the platform reach the design expectations, and the structural safety and functional reliability meet the requirements. The platform can meet the needs of in-situ collapse of towering chimneys by blasting demolition, and can also be used as a construction platform for the demolition of other high-rise structures with variable cross-sections.

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 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.

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.

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.