To study the influence of different geo-stress levels on the propagation of explosive stress waves in natural environment such as mountains and dams, numerical simulation technology was used to simulate the explosion of concrete specimens under different geo-stress conditions. First, by applying different stresses to the boundary of the concrete specimens, the failure of specimens subjected to explosive load were observed. And then, the peak stress and particle velocity of the four preset measuring points on the specimen were obtained by changing the unilateral ground stress value and keeping the same explosion load on different models. Finally, the influence of geo-stress on the propagation of explosion stress wave was analyzed on different characteristic parameters of explosion wave, such as the peak stress and particle velocity. The results show that the influence of geo-stress on explosion stress wave is mainly manifested as “restraining propagation” and “promoting propagation” under high and low stress level, respectively. During the explosion process, the superposition coupling of explosion stress wave and in-situ stress increases the peak stress intensity of the measuring point. On the contrary, the high ground stress inhibits the displacement of the medium particles, thereby reducing the particle velocity. The research starts from the influence of different ground stress levels on the propagation of explosive stress waves, and creatively analyzes the inhibition of ground stress on stress waves.

To solve the problem of impact danger to the coal pillars in the bearing section of the coal mine caused by rock burst, the stability analysis of the coal pillars was carried out using a theoretical analysis method during the excavation and backfilling periods of the B4328 working face of the Xinglongzhuang coal mine. The reasonable width of the coal pillars was calculated. A numerical calculation model was established using Phase2 to determine the stress distribution of the coal pillars in different mining states. Based on the degree of stress concentration on both sides of the roadway and the floor, a large-diameter borehole pre-pressure relief plan was implemented, and reinforcement measures for the transportation roadway before backfilling were also developed. The research results show that the plastic zone width of the coal pillar on the excavation side after transportation is 4.71 m and 14.45 m on the goaf. It is believed that the coal pillars are only affected by the impact of single-sided mining and the redistribution of drilling stresses, and the 25 m coal pillars are in a relatively stable state. At the same time, the simulation calculation shows that the transportation excavation area is located in the position where the supporting pressure peak drops in the goaf but the value is still relatively high, and the impact danger of the outer side of the coal pillar is greater than the inner side. Therefore, it is necessary to strengthen the support and take pre-pressure relief measures for the elastic area of the coal pillar. Because the coal pillar is less disturbed during the excavation period, and the two sides are basically in a plastic state after pressure relief, the elastic zone starts to produce plastic deformation, the elastic energy is released slowly, and the impact risk is reduced.

Dynamic disturbance scattering such as blasting generates dynamic stress concentration which is an important factor resulting in instability and damage in underground structures. In this paper, a theoretical model of a deeply buried pipeline under plane P-wave incidence is developed based on the wave function expansion method. Fourier transforms and Duhamel integrals were introduced to solve the transient response around a deeply buried circular aqueduct, and the effect of wavelength on the transient response was analyzed. Considering that the ground stress is a non-negligible factor for the destabilization of deep structures, a numerical model was established with the help of LS-DYNA finite element software to analyze the dynamic response mechanism of deeply buried pipelines under the action of the initial stress. The results of the study show that the compressive stress concentration generated by short-wave incidence is greater, and the tensile stress concentration due to long-wave incidence is greater, and the tensile stress concentration is very easy to occur along the direction of incidence. The larger the lateral pressure coefficient, the more pronounced is the suppression of the dynamic response in the presence of initial stresses. In addition, the pipeline and the surrounding rock mass under the initial stress state will experience more drastic fluctuations in the stress state when subjected to dynamic loading. These research phenomena reveal that the dynamic response mechanism of underground pipelines and the impact of the in-situ stress environment, which can be used for the seismic optimization design of deep underground structures.

Electronic detonators are the main initiation method currently used in the field of explosives engineering. However, they cannot be used in classroom or experimental teaching due to their high risk and special control requirements. It is urgent to develop a safe, reliable and reusable simulation device. Based on the STC15 microcontroller technology, a kind of analog electronic detonator for teaching was designed and tested. The simulated electronic detonators can be manufactured by 3D printing technology an they have been successfully applied to detonator detection and detonation network simulation experiments. The analog electronic detonator is mainly composed of power circuits, detonator simulation circuits, and PCB boards. A pair of leads protruding from one end of the detonator are connected to the power supply. Then, the microcontroller control chip, the drive circuit and the acousto-optic simulator are powered by the power supply circuit. After being powered on, the microcontroller control chip can drive the acous-to-optic simulator device according to the written program to simulate the operation of the electronic detonators. Thus, adjustable delay times have been implemented. In addition, the real blasting scene can be simulated, the internal structure can be visually observed, and series parallel stable operation can be realized. Through the experimental teaching, students can understand the structure and characteristics of electronic detonators, master the detonator performance detection method and detonation network connection method. The new analog electronic detonators can fully mobilize students' enthusiasm of learning the “blasting safety” course, give full play to the subjective initiative, and effectively improve their practical ability.

In the process of tunnel blasting excavation, the influence of ground stress and joints on the blasting effect of rock mass is significant, and they are two important factors that must be considered in the layout of tunnel blasting holes. The static and dynamic mechanical parameters of jointed slate were obtained by indoor experiments by taking the Tongan Expressway Bayue Mountain Tunnel as the engineering background. Based on the LS-PREPOST software, a three-dimensional numerical model of jointed rock mass tunnel blasting under different ground stresses (3 MPa, 6 MPa, and 9 MPa) was established to analyze the distribution of effective stress at different locations after blasting. A method for the layout of blasting hole network in jointed rock mass tunnel under different ground stresses was proposed, and the method was verified based on on-site blasting experiments. The results show that ground stress has a restraining effect on crack propagation during jointed rock mass tunnel blasting, and the greater the ground stress, the more obvious the restraining effect. The explosion stress wave will undergo multiple refractions and reflections at the joint location, leading to serious over-excavation. When the hole spacing of the contour holes in the grade IV rock mass was set to 45 cm and the linear charge density was set to 0.375 kg/m, the average over-excavation value was controlled within 20 cm. The designed concrete volume of the research section was 15.1 m³, and the actual concrete consumption in the three on-site tests was 26.4 m³, 23.7 m³, and 25.8 m³, with an average concrete excess consumption of 10.2 m³ and an average excess consumption rate of 67.5%, which were all controlled within 100%.

Smooth blasting is the main method for controlling excavations in hard rock tunnels, but due to the complex mechanism and process of rock fragmentation by blasting, as well as the rough design of blast parameters, it is difficult to achieve a smooth excavation profile for the entire tunnel. This study focuses on the Level Ⅲ hard rock section of the Zhaishan tunnel, and through a large number of blasting tests and investigations, it was found that there were problems such as over-excavation and under-excavation, misfire, and secondary blasting construction around the tunnel profile after the original blasting plan was carried out. Based on relevant specifications and engineering experience, optimization measures were proposed for the blasting parameters, including reducing the spacing between contour holes, increasing the number of relief holes, using water bag as the charge decking and stemming, as well as reducing the amount of explosives loaded in each hole. The results showed that the optimization measures can improve the utilization of explosive energy, achieve uniform fragmentation of the rock mass, and control over-excavation and under-excavation of the tunnel perimeter rock mass. The blast parameter optimization also results in smooth and round tunnel profile with clear blast hole marks, which helps to improve the quality of excavation and accelerate the progress of tunnel construction.

The estimation of equivalent and depth of underwater explosions is an important task of the hydroacoustic monitoring in the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). In order to effectively estimate the equivalent and depth of underwater explosion in near and far-fields, the relationship between the ratio of the first and second periods of the bubble pulsation and the bubble radius and depth was fully used based on the semi empirical formula of bubble pulsation period. The analysis results of near-field underwater explosion show that the average estimated equivalent and depth are about 118 g and 7.96 m, 76 g and 21.4 m, 1.23 kg and 44 m for different actual TNT equivalent values and blasting depths of 100 g and 7 m, 100 g and 25 m, 1 kg and 50 m, respectively. These results show that the depth estimation is more accurate than the equivalent estimation. Furthermore, the proposed method failed for a small explosion equivalent of 100 g and a depth of 50 m, which indicates that the method is limited in explosion depth. Finally, this method was used to analyze the far-field underwater explosions recorded by IMS hydroacoustic stations, and the equivalent and depth estimation results were consistent with the references, which indicated that this method is also suitable for the far-field explosion estimation.

In view of the problem of noise and information loss in the CEEMDAN method in the denoising process of actual measurement blasting vibration signals, the clustering analysis method is considered to have good data processing ability. Based on the idea of decomposition-clustering-reconstruction, CEEMDAN-K-means algorithm for denoising of blasting vibration signals is proposed. Firstly, this method decomposes the blasting vibration signal by CEEMDAN method to obtain IMF components of different quantity levels. Then, the K-means clustering analysis algorithm is used to classify the IMF components into five different categories, and variance contribution rate verification is used. Finally, the IMF components of high frequency noise category are removed and the reconstructed pure blasting vibration signal is obtained. Taking the blasting vibration signals from an open-pit mine as example, the signal denoising performance of the CEEMDAN-K-means algorithm was evaluated by signal-to-noise ratio and root mean square error indexes. The research results show that compared with the CEEMDAN method and the EMD-wavelet threshold method, the CEEMDAN-K-means signal denoising method has the largest signal-to-noise ratio (20.06 dB), which is increased by 1.26 dB and 7.7 dB, respectively, and the smallest root mean square error (0.22 10^-3), indicating that the method not only has good denoising effect, but also has good fidelity. Through the comparison and analysis of the denoising effect of different methods, it is known that on the basis of effectively retaining the real signal component, the CEEMDAN-K-means method can effectively remove the high-frequency components contained in the measured blasting vibration signal, and has practicality and effectiveness in the field of blasting vibration signal denoising.

The shock load of underwater explosion usually includes shock wave load and bubble pulsation load. The structural damage caused by shock wave and bubble load is always a hot topic in ship design. It is generally believed that the impact of shock wave load on the structure is mainly local damage, while the impact of bubble pulsation load on the structure is mainly global damage. The actual damage process of underwater explosion load is often the result of the joint action of the two kinds of loads. However, it is difficult to quantify the contribution of the two kinds of elements to ship damage. In order to study the damage effects of two kinds of loads on ships, a variable section box girder was used to simulate the surface ship structure, and its response process under the impact of underwater explosion was experimentally studied. Both the influence of distance on shock wave and the conditions for utilizing bubble energy were considered in the design of the experiment. The results show that plastic hinge was formed in the box beam structure near water surface under the action of near-field explosion load, and the energy transferred by explosion load to the beam structure was mainly converted into the deformation energy of the plastic hinge. In addition, the dynamic strain response of the structure gradually decreased from the middle to the end of the box beam, and the residual plastic deformation mainly occurred near the middle of the structure. The continuous large opening mode on the upper surface of the box beam resulted in larger plastic deformation of the deck side plate and the upper part than that at the bottom of the hull.

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.