When excavating a tunnel in a gently sloping strata, serious overcut and undercut problems occur in various parts of tunnel blasting construction due to the existence of horizontal weak interlayer. Based on the project of Baoanying tunnel of Chengdu-Kunming Railway which passes through horizontal sand-shale interlayers, LS-DYNA software is used to simulate the blasting effect with different layer thicknesses to propose reasonable blasting control parameters. And the reliability of the parameters is verified by field blasting tests. The main research results are as follows: (1) When blasting excavation in a horizontal rock layer, the damage range of rock mass along the horizontal direction is large with long cracks, especially at the junction of sandstone and shale. On the contrary, the damage range along the vertical direction, with a small explosive energy utilization rate. (2) The blasting effect of horizontal sand-shale interlayered surrounding rock is significantly affected by hole spacing and the thickness of soft shale. When the thickness of shale interlayer is thin, smaller hole spacing should be selected. With the increase of the shale interlayer thickness, the controllable cracks can be effectively generated by arranging the hole spacing and empty holes to achieve a better smooth blasting effect. (3) The optimal hole spacing of the surrounding rock blasting with different thickness of sand-shale interlayer is determined. When the shale thickness is 5 cm, 10 cm, 15 cm, 20 cm and 30 cm, the optimal hole spacing is 42 cm, 46 cm, 50 cm and 54cm, respectively. At the same time, the position of the blast hole must be strictly controlled to reduce the blasting vibration as much as possible.

In order to study the deformation and damage of tunnel surrounding rocks under the coupling action of static and dynamic stresses, a tunnel model under the coupling action of ground stresses and blasting loads is established. Firstly, the JH2 constitutive parameters of surrounding rock are deduced based on the on-site monitoring data of Wenbishan tunnel and the wave velocity of the rock mass. According to the surrounding rock grade, combined with the known parameters and wave equation, a simple method to determine the JH2 constitutive parameters is given, and the damage model of the surrounding rock is established by embedding a subprogram into ABAQUS. In order to make the simulation model closer to the reality, this research first balances the ground stress, takes the soil state at this time as the initial stress state of the blasting simulation, then using the equivalent blasting load method to simulate the tunnel blasting, so as to realize the blasting simulation for large-scale geotechnical engineering under the coupling of static and dynamic stresses on a macro level. The simulation model not only considers the blasting effect on the working face, but also focuses on the impact of blasting on the surrounding rock of the tunnel. The results show that the initial ground stress plays a significant role in the damage and deformation of the surrounding rock during tunnel excavation. The existence of the initial ground stress induces damage propagation. The greater the ground stress is, the greater the damage is. The maximum damage depth of the arch bottom in vertical direction is 2.2 m. At the same footage, the smaller the ground stress is, the greater the deformation is. The maximum deformation of 11.7mm is produced at the arch crown near the excavation face. The horizontal convergence deformation of the surrounding rock is different. The upper part is away from the tunnel, and the lower part points to the tunnel. In addition, the surrounding rock at the boundary between the upper and lower benches is subject to shear load. The damage and deformation of the surrounding rock are closely related to the actual project.

In order to study the blasting vibration prediction and control measures of excavation in urban area under complex environment, the response law of peak particle vibration velocity and main vibration frequency is analyzed based on field blasting tests, and the blasting vibration prediction method is proposed based on the above two factors. The vibration reduction effect of hole by hole initiation and vibration reduction ditch is discussed, so that to obtain the optimal vibration reduction range of the ditch. And the control measures of blasting vibration are also formulated. The results show that the prediction formula of the peak particle vibration velocity and main vibration frequency is realized by considering the actual maximum single-hole charge and the actual total charge. The predicted value is smaller than that solely based on the maximum single-hole charge, and the prediction accuracy is increased by 3.2%. In the aspect of blasting vibration control, the blasting vibration is characterized by low vibration velocity, high frequency and short duration. Among all the measures, the effect of the vibration reduction ditch is remarkable. Considering the peak particle velocity, signal frequency band energy distribution and instantaneous input energy response law, the vibration reduction effect is the best within 1~6 m radius on the side of the ditch opposite to the blast source, and the maximum vibration reduction ratio can reach 77.5% within 1 m radius. For similar projects, the proposed blasting vibration prediction formula can be used for pre-assessment. When the distance of the building from the explosion zone is less than 10 m, it is recommended to implement vibration reduction ditch.

In order to investigate the dynamic response and stability of a steep slope under blasting vibrations from multiple blasts, the displacement, stress, maximum shear strain, safety factor and sensitivity of the steep slope were analyzed by field monitoring, numerical simulation and mathematical methods based on the an open-pit mine in Inner Mongolia. The data fitting results show that the radial vibration velocity has the highest correlation coefficient, with all the coefficients of three directions greater than 0.8. The relative error of the prediction results is larger in the near-blasting area, while smaller in the far area. After a single blast, the horizontal displacement increases rapidly and reaches the maximum value on the right side of the blast hole at 0.05 s. In the vertical direction, the stress increases gradually from top to bottom and the bottom is prone to stress concentration. The overall stress distribution of the slope gradually increases from the slope surface to the slope interior. After multiple blasts, the displacement and horizontal stress of the slope generally continues to increase with the increase of blasting times. The peak value of vertical stress and acceleration are generally oscillating with the increase of blasting times. For a period after the blasting, the acceleration is still not 0, and it takes a long time for the blasting energy to completely dissipate. Multiple blasting vibration will continue to reduce the safety factor of the slope to a certain extent. With the increase of blasting times, the change rate of the safety factor of the slope will gradually increase. Based on the gray correlation coupling analysis of safety factor and orthogonal tests, the sensitivity of each factor is as follows: charge per delay (X₅) > total explosive charge (X₆) > hole spacing (X₃) > blast distance (X₂) > blasting vibration duration (X₄) > hole number (X₁). It is indicated that in actual construction, it is necessary to control the charge per delay and total charge in order to ensure safe production.

In modern blasting engineering research, the matching model of explosive and rock provides a scientific basis for revealing the internal mechanism of blasting process and predicting the economic benefits of blasting system, which has become an irreplaceable important tool. However, due to the diversity and complexity of soil-rock medium and the uncertainty of explosion process, the interaction between explosive and rock is more complex and uncertain, and it is difficult to study the matching of explosive and rock from their interaction process. Earlier studies mainly relied on empirical formulas and field tests for calculation and summary, which often had high eigenvalues and harsh application environment. However, the feature of machine learning is that it only considers the beginning and the result, and does not care about the middle process, which ensures its universality in the study of explosive-rock matching model. The XGBoost algorithm, together with multi-threading, data compression and fragmentation method, has the advantages of high efficiency in the case of largedata amount, and is suitable for training of a large amount of field data. In view of this, a field test was carried out in a mine in Guizhou province, and XGBoost algorithm was used to establish a matching system between explosives and rocks. The network was trained through successful examples, and the trained neural network was applied to practical projects. The results show that the performance of the explosives selected by the matching system based on this method is similar to that of the industrial explosives used at present, and the error is within±10%, which has a high reliability, and further verifies the rationality of the explosiverock matching system based on XGBoost algorithm.

In the teaching of demolition blasting, the structure modeling period and the cost of single experiment are both too excessive, and the experiment cannot be repeated in a short time. In addition, the experiment is transient, irreversible, and dangerous, which is not conducive to close observation and learning. Aiming at the difficult problems of experimental teaching in blasting demolition engineering, a platform of virtual simulation experiment is established for teaching design schemes. Firstly, through the two interactive operation links of “toppling scheme selection” and “cut design”, the learners can master the basis for the selection of toppling scheme and the design method of blasting cut, and understand the design content of blasting cut such as cut shape, orientation window and positioning window. It is easy by the platform for the learners to understand the stress conditions for cut design according to the mechanical principle of chimney toppling. They also should be familiar with the knowledge of tension zone, compression zone and neutral axis, and master the calculation formula of the extreme stress of the cut section and the application of strength conditions. Secondly, the platform system can make the learners participate in the design of powder factor, blast hole parameters and initiation network through “blasting parameter design”, and correctly select the detonators inside and outside hole. Then, through the interactive learning of “safety check” and “arrangement of shock absorption measures”, the learners can master the data collection steps, the safety check methods and measures to control the negative blasting effects. Finally, the learners can experience the on-site blasting operation process by the “blasting site” module, and gradually establish their understanding of the blasting operation process by participating in the design and organizing each construction step. In addition, the experimental system has a knowledge introduction for each module, which is convenient for learners to learn independently. The construction of the virtual simulation experiment platform not only optimizes the teaching methods, but also improves the teaching quality, and enriches the characteristics and innovative ideas of the experiment teaching of engineering blasting.

In response to the high-quality requirements for large-diameter deep-hole blasting, and the traditional stemming material being too long and prone to “blowout”, a new type of blasting hole stemming material was proposed using early strength cement mortar and a bag-like structure. Static mechanical tests and blockage model tests under impact loads were conducted on cement slurry with different admixture contents and ages, and the self-shrinkage performance, compressive strength, and passive confinement pressure of the cement mortar under impact loads were analyzed to determine the dynamic mechanical properties of the early strength cement mortar under passive confinement. The stress characteristics of the stemming material in the blasting hole under the pressure of the blasting gas were also analyzed to provide a reasonable stemming length for large-diameter deep-hole blasting. The results showed that the self-shrinkage of the test piece increased with the increase of admixture content. The compressive strength of the test piece increased with the increase of age and decreased with the increase of admixture content. With the increase of admixture content and age, the expansion pressure increased, resulting in an increase in passive confinement pressure. When the admixture content was 4%, and the age was 16 hours, the expansion pressure reached its peak at each measuring point. Additionally, with the increase of admixture content, the porosity of the slurry increased, the axial compressibility of the blocking material increased, and the acting time of the blasting gas pressure in the blasting hole was prolonged, which improved the stemming quality. Comprehensive on-site test results have shown that the stemming length, reasonably selected based on the derived theoretical formula and combined with on-site production, ensures safe production during the mining period, and achieves good results in deep-hole blasting.

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.

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.

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.