In order to study the energy evolution and fracture characteristics of sandwich composite rocks under impact loads, six sets of sandwich composite rock specimens were created using three materials: sandstone, marble, and granite. Dynamic fracture impact tests were then conducted using the Hopkinson pressure bar system to analyze crack propagation morphology, stress wave waveform characteristics, crack tip stress field, and energy loss relationship. The DLSM simulation results were also used to analyze the propagation law of stress waves and the evolution process of kinetic energy during dynamic fracture processes. The results showed a good fit between the dynamic fracture process captured by high-speed cameras and the crack propagation process simulated by DLSM. It was observed that the occurrence of cracks depends on the failure of weak bedding planes. Under the same impact conditions, the lower the strength of the weak bedding planes, the shorter and more advanced the crack propagation time, and the more energy is used for crack propagation. Additionally, under the same incident energy conditions, using a specimen with higher hardness as the impact end material results in a stronger reflection effect, greater reflection energy, weaker transmission effect, smaller transmission energy, and greater energy dissipation of the specimen. The bedding plane was found to have a significant hindering effect on the propagation of stress waves.

To accurately predict the peak particle velocity (PPV) and effectively reduce the hazards of blasting vibration, a prediction model was built by BP neural network based on the blasting project of Xingguang No. 1 openpit mine. Seven influencing factors as core distance, plugging length, minimum resistance line, explosives unit consumption, maximum single-hole charge, total extension time, and maximum single-delay charge, were selected as input variables, and the correlation between each factor and PPV was evaluated by using the grey correlation analysis method. The Sparrow Search Algorithm (SSA) optimized the BP neural network to predict the three-way peak vibration velocity. By comparing and analyzing the prediction results of the BP neural network model, the average errors of the prediction results of the SSA-BP neural network model were 6.08%, 7.34%, and 1.91%, respectively, and that of the prediction results of the BP neural network model was 22.19%, 54.01%, and 25.29%, respectively. The results show that the SSA-BP neural network model comprehensively considers the influence of multiple blasting design parameters on the peak vibration velocity. The sparrow search optimization algorithm can effectively solve the problem of the traditional BP neural network model, which quickly falls into the local optimum. The prediction results are more accurate, and the vibration velocity monitoring value is more consistent with smaller errors. Meanwhile, it can significantly shorten the learning and training time of the sample data to speed up the convergence speed of BP. Additionally, it can also significantly shorten the training time of sample data and accelerate the convergence speed of the BP neural network prediction model.

Dynamic mechanical tests were carried out on EPS concrete at early ages (12 h、24 h and 36 h). Whereafter, the influences of impact velocity (4.5~6.5 m/s) and age (12 h、24 h and 36 h) on impact resistance of EPS concrete were analyzed in terms of dynamic compressive strength, peak strain, ultimate strain and energy dissipation density. Additionally, the properties of EPS concrete at early ages were compared with that at the age of 28 d. The results show that the dynamic compressive strength, peak strain, ultimate strain, and energy dissipation density of EPS concrete have an impact on the velocity-strengthening effect. With the increase of age, the dynamic mechanical property indicators of EPS concrete and its sensitivity to impact velocity increase. At the age of 28 d, the dynamic compressive strength, peak strain, ultimate strain and dissipation density of EPS concrete are the maximum, and its sensitivity to impact velocity is the strongest. EPS concrete has good deformation and energy absorption characteristics at the early age. At the age of 36 h, the peak strain, ultimate strain and energy dissipation density of EPS concrete can reach 66%~82%, 91%~93% and 72%~78% of that at the age of 28 d, respectively.

Aiming at the problem of reasonable spacing-burden ratio in wide hole spacing blasting technology, laboratory blasting experiments of PMMA plates with the spacing-burden ratios of 1.7, 2.5, 3.5 and 4.5 were carried out based on related rock fragmentation mechanism at home and abroad. Meanwhile, a blasting calculation module was developed to study the crack propagation process and the response law of displacement based on the principle of near-field dynamics of conventional modes. The results show that the radial cracks present the character of branching to the corner of the free face and finally form the main cracks of a funnel shape, affected by the reflected tensile stress wave. Under the condition of fixed minimum resistance line, the stress reduction area gradually increases with the increase of the spacing-burden ratio, and the radial cutthrough cracks between the blastholes in the same row disappeared. An excessive spacing-burden ratio will further cause the disappearance of the cutthrough cracks between two rows of holes, and finally lead to the occurrence of individual hole blasting. The displacement results further confirm the above rule, and the rock ridge left by the front row of holes is just broken by the rear row of holes when the spacing-burden ratio is small. This breaking effect gradually decreases with the increase of the spacing-burden ratio. It is suggested that the spacing-burden ratio should be appropriately adjusted according to the mechanical properties of rock mass, geological conditions and blasting purposes to reduce explosive consumption and boulder yield in practical projects.

In order to explore the blast-induced crack propagation behavior in rock mass with two vertical prefabricated defects, a series of blasting experiments of models with double vertical cracks were carried out based on digital laser caustics. The evolution process of blast-induced crack is shown and the effect of single-hole charge on the crack propagation behavior (crack propagation length, stress intensity factor, propagation velocity, and initiation time, et al) in rock mass with defects was explored. The results show that the crack propagation length, propagation velocity, crack initiation toughness and stress intensity factor at the end of the double vertical cracks increase with the increase of single-hole charge. For crack J_u, the effect of single-hole charge on crack propagation velocity is small, and the limit velocity of crack propagation is about 0.38 times of the shear wave velocity. For cracks D_l and D_r, the initiation time decreases, but the peak stress intensity factor increases with the increase of single hole charge. Besides, the stress intensity factor and propagation length of crack D_r increases significantly compared with crack D_l. The crack D_l starts to crack earlier than the crack D_r when the energy of the blasting stress wave acting on both ends of defect B is enough to cause the crack to propagate on both sides. The increase of charge in a single hole can increase the propagation velocity of crack D_r, but has little effect on the propagation velocity of crack D_l.

The smooth blasting technology is the main means to control the over excavation and under excavation of tunnels at present. In order to explore the influence of the charge structure and charge amount of peripheral holes on the blasting effect, a series of single hole blasting tests were conducted in the silty shale section of Wulong Tunnel. The results show that the best blasting effect for detonating cord initiation can be achieved when a decked peripheral hole is charged with 0.1+0.075 5 kg of explosive. At this time, the residual rate of peripheral holes is 96%, and the average linear overbreak is 15.3 cm. On the other hand, the best blasting effect for detonator initiation happens when the charge amount of a peripheral hole is 0.45 kg, with the residual rate of peripheral holes as 90% and the average linear overbreak as 18.4cm. When a continuous charging structure is adopted for the peripheral holes, the best blasting effect appears as the charging amount is 0.3/0.45 kg. In this case, the residual rate of surrounding holes is 32% and the average linear over excavation amount is 24 cm. The decking charge structure of the peripheral holes can effectively improve the blasting effect, which ensures the residual rate of peripheral holes is more than 50% and reduces the tunnel over-excavation. By comparison, the blasting effect, in the order from best to worst, is ranked as detonating cord with decking, detonator with decking and continuous charge, respectively. And their residual rates of peripheral holes are more than 90%, more than 70%, and less than 50%, respectively. It is proved that both the detonating cord with decking charge structure and the detonator with decking charge structure can be used for surrounding holes to control tunnel over-excavation.

Structural plane is one of the key factors controlling the local stability of rock mass engineering. It is a prerequisite for rock mass stability analysis to find out the occurrence and combination of structural planes. Geological survey is often used at present. However, a high-cost supplementary survey is often needed when there are omissions due to the limitation of this survey means. Therefore, the surface vibration response law of the structural plane model was studied by laboratory tests. The study shows that the amplitude of the particle in front of the structural plane increases for the single structural plane model. For a block model cut by two structural planes, the amplitude-amplification effect exists only in front of the structural plane far from the power input side. Furthermore, the rock mass models with different structural plane dip angles were simulated respectively. The results show that, when the angle θ between the structural plane and the ground in the direction of the explosion source is less than 90°, the particle amplitude in the incident area of the vibration wave in front of the structural plane has an obvious amplification effect, and the particle amplitude behind the structural plane significantly attenuates. With the decrease of the angle θ between the structural plane and the boundary plane, the increase rate of the peak vibration velocity of the particle in front of the structural plane gradually increases, and the amplitude of the wave amplifies 2.8 times when θ=20°.

For the purpose of studyingTo study the influence of hydration rate of static explosives on the mechanical behavior and damage mechanism of coal ore body, numerical simulations of ore body mechanical damage were carried out using a stress-damage coupling model under different hydration rates. The impact of hydration rate on the evolution of stress field and damage zone in the ore body was analyzed, and the mechanism of the effect of drilling arrangement model on hydration rate was revealed. The research results indicate that the development of the damage zone in static blasting can be divided into four stages: compaction stage, micro-damage formation stage, damage zone development stage, and damage zone connection stage. Among them, the stages of damage zone development and connection stages show the most significant stress effects. The stress field and damage zone increaseincreases with the increase in of hydration rate. Specifically, and the influence of hydration rate on the stress field and damage zonesuch kind of influence is relatively small during the initial rapid energy release phase, but becomes significantly different in the later stages. Besides, Tthe borehole arrangement model affects the mechanism of hydration rate. withUnder the single-hole mechanical model, the hydration rate promotes expansion pressure differences, while However, the under the double hole mechanical model, hydration rate promotes stress superimposition forunder the double hole mechanical model. The guided hole arrangement model has the most significant effect, where the initial hydration rate accelerates stress transfer and the later hydration rate promotes stress superimposition, leading to the expansion and connection of the damage zone under the combined effects of time and stress dimensions. In the numerical simulation and field tests scheme of this study, the hydration rate of the static blasting agent was 1.8 MPa/min, the blast orehole diameter was 113 mm, the borehole spacing was 1000 mm, and the reasonable ratio of borehole spacing to diameter (η) was 9. The guided hole arrangement model can effectively fractures the ore body and generatees a large number ofmany damage zones. This research provides a reference basis for improving the fracturing effect and construction arrangement of static blasting technology.

The distribution characteristics of blasting pile is an important index indicator to evaluate blasting effect. In view of the inadequacy of the current direct and indirect methods of measuring fragment size of the blast pile, a spatial distribution measurement method for adaptive stratification of the blast pile is proposed. It uses the GA-LSSVM model to predict the shape parameters α and β of the Weibull function and sets multiple prediction points to predict the three-dimensional blasting pile morphology. By converting and fusing the parameters of the Kuz-Ram fragment prediction model, a distance prediction model of blast pile stratification is established and applied to the Weibull-GA-LSSVM model to achieve an automatic stratification of the blast pile. Through field application, the stratification design is continuously optimized for the best stratification position to realize the adaptive stratification. The results show that: (1) the Weibull-GA-LSSVM model can accurately predict the morphology of the blast pile with a good stability that the average relative error of the prediction results of the maximum forward distance of the blast pile is only 5.6% and the relative error of the prediction results of the looseness coefficient is mostly around 9%. (2) The Kuz-Ram-based blast pile stratification model can reasonably output the layer distance and number before blast, which ensures the shoveling efficiency after blast. (3) The optimal layer distance formula is derived to achieve the adaptive stratification of the blast pile, and the measurement accuracy of the fragment size distribution of the blast pile is significantly improved, which is closer to the overall fragment size distribution.

Most of the buildings in the mountain city area are built on leaning the mountains, with the characteristics of uneven terrain, scattered architectural layoutscattered layout of buildings and complex surrounding environment. In a certain area of Chongqing, there are were 10 frame-shear wall structure illegal buildings with a frame-shear structure that need to be demolished. Due to the requirements of construction safety and progress, single incision directional blasting demolition is was determinedadopted. Combined withBased on related the practice experience of blasting demolition project, according to the plane position, spatial distribution characteristics and surrounding environment of 10 illegal buildings, thean corresponding overall blasting scheme is was put forward according to the plane positionlayout, spatial distribution characteristics and surrounding environment of the 10 illegal buildings. And optimizing construction organization, tThe blasting demolition task of this building group is was completed safely and efficiently in three times within 15 days under an optimizding construction organization. In view of the environmental factors such as high and steep rock slopes, valleys and scarps that which affect the collapse of the building and the blasting effect, the directional collapse of the buildings can bewere reliably guaranteed by optimizing the blasting incisions, reserving buffer layers, and rationally designing blasting parameters. Through the rational reasonable design of the partition sections and delay times of firing circuitthe initiation network, and efficient organization of the circuit connection operations, the athe reliable delay initiation of large-scale industrial electronic detonator network is was realized. Finally, the collapse accumulation range and blasting harmful effects of building arewere effectively controlled. The collapse of eEach building is was fully disintegrated, the blasting heap piles fragments arewere concentrated, and all kinds of surrounding protection objects are were safe. The engineering practice results show that the initiation network of industrial electronic detonators initiation network can meet the needs of multi-unit and multi-level large-scale initiation network, which provides an important reference for similar projects.