At present, mining method is widely used in tunnel construction. The influence of blasting vibration on surrounding rock and supporting structure in tunnel and its disaster control are always hot issues. In order to study the propagation law of blasting vibration inside a tunnel, the vibration signals of simultaneous detonation and detonation at three benches were monitored on site based on the engineering background of a tunnel with soft surrounding rock. The nonlinear regression of Sadovski formula and Fourier transform method were used to analyze and study the test data. The results show that for the same section of the tunnel, the vault has the characteristics of large vibration velocity, high vibration frequency and slow attenuation rate. When 100 ms delay blasting is used between the three steps, the blasting energy can be discretely distributed in time and space, and the vibration superposition effect can be significantly weakened. A single hole blasting test was set in the middle of the cut area, and the single hole vibration waveform was obtained by setting the delay between the test hole and the entire blast as 100 ms. Based on the principle of linear superposition, the delay time was optimized by investigating vibration waveforms synthesized by cut blasting. The results show that when the delay time between holes is 4~7 ms, the peak vibration velocity caused by cut blasting decreases sharply, and the effect of interference is obvious. After the delay time exceeds 7 ms, the peak vibration velocity has no significant difference.

To explore the destructive forms of bridge damage caused by explosions of hazardous materials in vehicles and the distribution of explosion load pressures on the bridge deck, a refined numerical model was established using AUTODYN software. The study analyzed the regional distribution characteristics of the bridge load pressure field under various explosion conditions with different shapes and sizes of steel plates, and determined the critical dimensions at which the steel plates play a blocking role against shock waves. In response to the challenges of conducting bridge explosion experiments, which involve high risks and large expenses, the research referred to a detailed inspection report of a real bridge after an explosion accident and inferred its explosion damage process. Based on the least squares method, a polynomial curve fitting was applied to numerous of numerical calculation results, and the traditional calculation formula for explosion shock wave pressure in the free air domain was modified. A prediction formula for the peak overpressure on the bridge deck under the explosive effects from the vehicle-borne cargo, taking into account the blocking of carriage steel plates, was proposed. The load pressure distribution calculated by this formula corresponded well to the damaged areas on the bridge deck as reported in the real bridge inspection report.

The slope stability is bound to be affected in the blasting process of open-pit mine, especially when the slope is in the karst area. In order to study the influence of karst on slope stability under blasting and based on Tangya limestone mine slope project, this paper takes the exposed karst at the 1014 m platform of the mine as the research object, and uses ANSYS/LS-DYNA finite element analysis software to conduct numerical simulation. Considering the effect of blasting vibration, the stress distribution of the surrounding rock is obtained, and the effects of blasting on slope stress, vibration velocity, rock damage and effective stress of slope with or without karst cave are compared. The results show that the force of the bench changes and stress concentration occurs for several times due to the existence of karst caves, but the stress value generated by the bench loads is only 7.6 MPa, which still cannot reach the degree of rock mass destruction. For monitoring points at different spatial locations, the difference of vibration velocity becomes larger due to the existence of karst caves, and the vibration velocity in the vertical direction changes more than that in the horizontal direction. In particular, the spatial locations of the monitoring points near the slope edge are more sensitive to this situation. The vibration velocity difference of the monitoring points on the slope edge is about 1 cm/s at most, which does not exceed the allowable vibration velocity. In the process of increasing blasting times, the damage inside the rock mass is also gradually increasing, and the damage is more obvious under the influence of karst caves. The larger the radius of karst area, the more blasting times, the more serious the damage. Compared with previous uniaxial compressive strength experiments, it is found that although the existence of karst caves will cause the change of stress value and stress concentration phenomenon, the peak effective stress generated is far lower than the uniaxial compressive strength of rock mass. In view of the influence of blasting process on slope stability, the support treatment measures of slope in karst area are put forward.

Reinforced concrete (RC) short beam is the key load-bearing component of buildings. In order to study its dynamic response and failure mechanism under impact load, drop hammer impact tests with different impact mass, impact velocity and impact energy were carried out by combining strain gauge sensor, high-speed photography and digital image technology (DIC). The results show that, the failure forms of the short RC beams under impact loads are arch collapse cracks and overall bending deformation, which are obviously different from those of shallow beams. The axial strain in the mid span of a short RC beam changes from tensile strain to compressive strain. With the increase of impact energy (18 061 J≤E≤49 831 J), the axial peak tensile strain and residual compressive strain in the mid span increase first and then decrease. The short RC beam is in the stage of elastic flexural deformation, elastic-plastic flexural deformation and punching shear failure mode in turn. The crack initiation and propagation process of the short RC beam under impact load is not unidirectional. And the fracture zone is formed by the multidirectional fracture propagation with multiple times, and then the plastic hinge is formed, resulting in the overall short beam failure. The deformation degree of the beam mainly depends on the impact speed rather than the impact energy. Specifically, the peak deflection and residual deflection in the middle span of the beam (26.81 mm≤w_p≤29.85 mm; 17.12 mm≤w_r≤21.66 mm) increase with the increase of the impact speed (5.53 m/s≤v≤7.13 m/s) under the same impact energy (30 000 J).

Ground blasting vibration control is one of the key contents in the blasting construction of subway tunnels in complex urban environment, and cut blasting is the key to determine the blasting vibration intensity. Combined with the actual project of the north extension line of WuHan Metro Line 7 (Qianchuan Line), an optimization design was carried out on the basis of the original blasting cut method. The numerical simulation and field vibration test verification methods were used to calculate and compare the blasting vibration effects of single wedge cutting, burn cut with four holes and double wedge cutting. Then, the optimization method of cut blasting was proposed. The results show that single wedge cutting, burn cut and double wedge cutting have similar propagation rules of blast vibrations along the axis of tunnel excavation. The peak vibration velocity along the x direction (horizontal radial) decreases with the increase of the distance from the working face in the range of 0~-5 m. When distance exceeds 5 m, the peak vibration velocity increases first and then decreases. The excavated area of the upper bench of the left pilot tunnel has an amplification effect on the surface vibration velocity, which is referred as a “cavity effect”. The distribution of the x-direction (horizontal radial) peak vibration velocity on the left and right sides of the tunnel is roughly similar, and gradually decreases with the increase of the horizontal absolute distance from the origin along the direction perpendicular to the axis of tunnel excavation. The upper bench of the left pilot tunnel has a free face, which makes the peak vibration velocity along the x direction (horizontal radial) on the left side of the tunnel bigger than that on the right side. Due to the delayed initiation, the peak vibration velocity along the x direction (horizontal radial) by double wedge cut blasting is the minimum. The surface vibration velocity of the excavated area is 1.35~2.02 times than that of the unexcavated area ahead during the tunnel blasting construction, due to the “cavity effect”. Compared with other cutting methods, the “cavity effect” of the double wedge cutting is weaker. The comparative analysis of blasting vibration intensity of the three kinds of cutting modes shows that the order of advantages and disadvantages of the three kinds of cutting modes is: double wedge cutting > single wedge cutting > four straight hole cutting.

In order to improve the quality of tunnel blasting and reduce the disturbance to surrounding rock during blasting construction, it is necessary to carry out optimization research on the original blasting scheme. Taking the parallel guide tunnel of a railway project as the engineering background, more reasonable blasting parameters are determined by using the empirical formula to calculate the powder factor, the number of holes and the parameters of each hole, aiming at the problems such as serious over-under excavation, poor working environment and slow construction progress. The number of medium and large diameter empty holes in the original blasting scheme is changed from 8 to 2, and the layout of cut holes is adjusted to provide better free surface for subsequent holes. At the same time, the orifice of the charging structure is blocked by water bags, which reduces the concentration of dust and harmful gases in the tunnel after explosion. The results show that the average linear over excavation can be reduced from 0.2~0.4 m to 0.15 m with smooth working face and bottom by using the optimized blasting scheme. At the same time, compared with the original scheme, the number of holes and the amount of explosives used in each cycle can be reduced by 37 and 49.2 kg, respectively. In addition, the construction time can be saved by 1.1 h and the cost is about 800 yuan, which has a relatively significant technical effect and economic value, and also verifies the feasibility of the optimized blasting scheme.

Using traditional continuous charge blasting method in Zijin Mine is easy to produce powder near the crushing circle of the hole, resulting in substandard ore gradation and waste of resources. Therefore, in order to improve the ore gradation and increase the aggregate products, a blasting test was carried out under the conditions of 0 m, 1 m, 1.2 m, and 1.5 m in the middle of the air-decked charge blasting technology. Firstly, a limestone model using HJC constitutive relation was established to simulate the actual geological by ANSYS/LS-DYNA finite element software. And then, the damage distribution characteristics of rock mass under different spacing distance conditions were analyzed, and the relatively optimal air spacing charge length was obtained. Finally, the 1.2 m and 1.5 m middle air decking are selected to control the blasting powder rate. The field blasting tests and the comparison of rock gradations under different conditions show that it is effective to reduce the powder rate by adopting the intermediate air decked charge. When the air decking length is 1.5 m, the non-uniformity coefficient Cu and the blasting powder rate can be reduced. Before the technical transformation, the average powder ore rate is about 15.94%, and after the technical transformation, the powder ore rate below 4.75 mm can be reduced to about 9.37%, making the grading to a good level.

In order to solve the existing problems in the explosive welding technology of clad metal plate, such as low utilization rate of explosive energy, environment harm and potential safety hazard, a simple closed explosive charging process, namely a production method of energy-saving explosive welding of clad metal plate, was designed. More precisely, an isolation plate with a thickness about 2 mm was placed on the surface of ordinary explosive, and a 10~12 mm height emery sands layer was laid on the isolation plate. Then, experimental research was conducted to verify the difference of the mechanical properties between the energy-saving explosive welding and the ordinary explosive welding. Non-destructive testing and mechanical properties tests showed that the interface binding strength, binding rate and mechanical properties of clad metal plates produced by the energy-saving explosive welding technology could meet or exceed the technical requirements of the national standard GB/T 8165 and industry standard NB/T 47002. The new method of covering something on the explosive surface can achieve the purpose of saving 1/3 energy compared with the ordinary explosive welding process. And even under the condition of reducing the explosive consumption by 30%, the mechanical performance index of the clad metal is still higher than the national and industrial standards. The experimental results show that the mechanical properties of the clad metal produced by the energy-saving explosive welding process and ordinary explosive welding process are almost the same, which can meet the needs of large-scale chemical equipment manufacturing field. Therefore, the production process of clad metal plate by the method of energy-saving explosive welding is simple, efficient, safe and reliable, and the purpose of saving energy as well as reducing consumption is realized.

In order to solve the problem that excessive blasting vibration affects the safety of village buildings (structures) on the earth's surface during the mining process of an underground orebody, the inter-hole delays of 8 ms, 10 ms, 12 ms, 14ms and 18ms and inter-row delay of 100 ms were selected for tests in the #63113 ore room of the orebody III in the mine. By combining the actual situation of the site and the empirical formula, the natural vibration frequency of the brick-concrete buildings with 1 to 2 floors in the village was 7.63~13.23 Hz. The blasting vibration data was collected on site and HHT transformation was applied on the measured blasting vibration signals by MATLAB. The characteristics of the signals were then analyzed from the perspectives of time domain, frequency domain and energy. The highly adaptive EMD decomposition was used to decompose the original vibration signal into the IMF components which were transformed by 10-layer db8 wavelet transform and the proportion of energy in the total energy of the frequency band 7.8~15.7 Hz of level 9 was summarized. The three-dimensional Hilbert spectrum and marginal spectrum were obtained by Hilbert transformation of the reconstructed signal with the IMF components. Through EMD decomposition and wavelet transform research on the blasting vibration signals, it is concluded that the three-direction energy ratio corresponding to the 12 ms delay time at No.3 measuring point is reduced by 14.07%, 24.89% and 6.26%, respectively. The experiments show that the problem that the problem that the low frequency energy takes a large proportion in the total energy can be improved by optimizing the inter-hole delay, and the resonance effect can be effectively avoided. By comparing the Hilbert marginal spectrum and the three-dimensional Hilbert spectrum with different delay times, the main vibration frequency and the maximum instantaneous energy of the blasting with an inter-hole delay of 12 ms appear 200 ms after the detonation, concentrated in the range of 30~40 Hz which is higher than the natural vibration band of the buildings, and thus have the least influence on the structures.

In order to ensure the construction quality of large section shaft horsehead gate and reduce the damage caused by blasting, an advance crack zone blasting technology is put forward. According to the section design and engineering geological conditions, the section of Matoumen excavation, the gates at-199.5 m and-258.2 m of a certain underground mine are divided into upper layer, middle layer, and lower layer excavation zones. The construction sequence is: upper layer→middle layer→lower layer. Firstly, the advanced fracturing holes should be constructed along the excavation contour lines of each layer. The hole depth is equal to the driving depth of the horsehead gate. They are charged with decks and detonated before the main blasting area, which can achieve mutual penetration between holes. The "shock absorption ditch" shall be formed along the excavation contour lines of the horsehead gate, which can reduce the effect of blasting seismic wave propagation. Besides, each construction area of the horsehead gate is equipped with hole by hole millisecond delay detonations with an interval of 5~20 ms, which can achieve the interference and offset of the vibrations from the subsequent blasting and reduce the blasting impact on the large cross-section horsehead gate. It has been validated that the half-wall hole rate of the excavation contour line is higher than 95%. It can not only meet the requirements of controlling the quality of roof forming for the excavation of large cross-section gate in broken rock mass, but also reduce the cost of support and shotcrete.