To control the height and recoil distance of a frame-shear wall structure after demolition by blasting, a frame-shear wall residential building demolition project in Qingdao was chosen as the subject. The simulation analysis used ANSYS/LS-DYNA software and the orthogonal combination of collapse angle and crotch extension time difference. Firstly, a finite element model of the original scheme was built, and the model's validity was checked by comparing the variance between the model prediction and actual outcomes. Then, the trends of the structure recoil distance and burst pile height with the change were analyzed by changing simply the model's inter-span extension time difference and cut height. Furthermore, the semi-quantitative formulas for the relationships between recoil distance and burst height with notch height and inter-span delay time difference were proposed based on the outcomes of multi-scenario numerical simulation, which were allowed for the determination of the inter-span delay time difference and notch height for the cases of minimum structural recoil distance and burst height, respectively. Finally, the analysis was carried out on the acceptable span-to-span extension time difference and the range of blasting notch heights for demolition blasting of frame-shear wall structures. The results show four fundamental steps to the collapse of frameshear wall structures: blast notch creation, destabilized overturning, notch closure, and landing collapse. The study's findings indicate that the recoil distance of each model primarily increases at first and then decreases as the interspan extension of the blast section is prolonged at the same cut height. Meanwhile, there is a more significant disparity in the structure's recoil distance as the deferred time difference is extended, and the recoil distance increases with the height of the blast cut at the same inter-span extension. Additionally, the height of the detonation pile roughly decreases as the time lag increases. The shear walls simultaneously improve the structural integrity and prevent the building from collapsing during the collapse, resulting in better structural integrity after collapse. The structure reduces recoil distance when employing a short incision height and a 200 ms extension time difference. The most minor burst heights of the structures are those with considerable notch heights and a 300 ms delay time difference. A crotch delay time difference of between 270 and 420 milliseconds is adequate. More importantly, a large blast cut can lower the pile's height, while a tiny blast cut can effectively regulate the recoil. It can be reasonably chosen based on the demands of the area around the structure that will be torn down. The study can provide a guide for determining the incision height and delay time difference for demolishing frame-shear wall structures by blasting.

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.

To solve the problem of the filling bodies failure on both sides of the room caused by differential blasting of large diameter deep holes in underground mine, the stress field generated by differential blasting should be studied to determine a reasonable edge hole spacing and a delay time between the holes. According to the stress wave propagation and attenuation law, the front and rear detonation hole distance, delay time, and edge hole distance generated by complex stress field were determined. Furthermore, the superposition of the stress wave generated by the two-hole differential blasting in the blasted rock mass and the filling body was analyzed according to the wave theory. The stress field function analytical formula of the two-hole differential blasting was obtained. Meanwhile, the collapse range of the blasted rock mass and the failure range of the filled body under different side hole spacing conditions under the same hole spacing and delay time were determined. The LS-DYNA numerical simulation software established six numerical models, and the stress critical points were selected in the blasted rock mass and filling body for analysis after simulating the initiation of explosives under different schemes. The simulation results show that different edge hole distances had almost no effect on the collapse range of the exposed rock mass when the distance between edge holes was more significant than the range of the crack zone. Appropriately increasing the distance between edge holes can effectively reduce the damage caused by stress waves to the filling body. Finally, the field industrial test of four groups of blasting parameters was carried out, and the optimized blasting parameters were determined as the spacing between the two holes on the same side was 2.0 m, the delay time between the front and rear initiation holes was 9 ms, and the side hole spacing was 1.8 m.

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.

In open-pit bench blasting, blasting TBlasting toe rocks is an important indicator to measure the blasting effect in open-pit bench blasting, and it is most directly influenced by the blasting parameters have the most direct influence on the formation of blasting toes. In order to find outresearch the influence of ultra-deepsubdrilling on the smoothness flatness of bench in deep-hole bench blasting, statistical analysis of the relationship between damage variables and wave velocity in rock mass was conducted based on the basic theories of rock damage mechanics. based on the basic theories of rock damage mechanics and through statistical analysis of the relationship between damage variables in engineering and wave velocity in rocks, Tthe threshold values of damage variable, D_d for critical damage variable damage state of of rock mass is determined as Dd that is was 0.2, and the damage threshold D_t of for rock breaking mass in critical broken state is was were defined as 0.2 and 0.8, respectively. based on the basic theories of rock damage mechanics and through statistical analysis of the relationship between damage variables in engineering and wave velocity in rocks. Furthermore, Based on the dynamic damage model of rock with comprehensive consideration of the damage effect of tension and compression, the damage range of bench blasting under different conditions of with different subdrilling conditionsultra-deep was simulated by using the dynamic finite element analysis program LS-DYNA based on the dynamic damage model of rock mass with a comprehensive consideration of tension and compression effect. Meanwhile; based on the threshold of critical damage variable, the fluctuations distribution image of the bench surface after blasting was drawn to determine the optimal ultra-deep of subdrilling hole based on D_t the threshold of critical damage variable, and the image is was used for the quantitative analysis, so as to ensure that the rock mass of upper bench was fully damaged without affecting the construction of the lower bench surface. Finally, combined with the actual situation of deep-hole bench blasting in Ezhou Airport, the influence mechanism of ultra-deepsubdrilling on blasting toes is was verified in the deep-hole bench blasting of Ezhou Airport, and an optimal method for determining the optimal ultra-deepsubdrilling value for deep-hole bench blasting is was concluded.

In order to investigate the dynamic response, damage evolution and failure of concrete tunnel structure by underwater explosion load, laboratory tests and numerical calculations are adopted in this paper. Firstly, a 40∶1 specimen was designed according to the East Lake underwater tunnel. An explosion test of the underwater box concrete tunnel model was then carried out. The dynamic response rule of the concrete specimens under different emulsion explosive equivalent was compared by monitoring the strains. Meanwhile, the failure forms of the scaled model of the box tunnel caused by the underwater blasting load were investigated by measuring the size of the failure range and the length of crack propagation. Furthermore, a 1∶1 modeling simulation analysis of the test was carried out using the S-ALE algorithm in ANSYS/LSDYNA. It is found that the simulation results were basically consistent with the experimental results by comparing the experimental data and failure patterns. At the same time, the complete propagation process of the underwater explosion shock wave and the deformation law of the specimen structure were obtained by further analysis of the simulation results. Finally, the dynamic response mechanism of the box tunnel specimens under explosion load was revealed through statistical analysis of strain and displacement data at the measuring points. The results show that the transverse strain of the box concrete tunnel structure is much larger than the longitudinal strain. The failure location of the tunnel is mainly concentrated in the area near the explosion source and the structural angle position. It is verified that the S-ALE algorithm can simulate the dynamic response and damage evolution of the structure by underwater explosion accurately.

In order to carry out the controlled blasting of two 200 m reinforced concrete bridges (an old continuous beam bridge and a new arched bridge) under complex environment, the piers of the two bridges, the webs of the continuous beam and the double-curved arch foot of the arch bridge were selected as the blasting locations, and the main bearing parts of the bridges were destroyed. Furthermore, deep hole blasting method and shallow hole blasting method were adopted for the pier and main beam respectively to improve the construction safety and efficiency. Specifically, large-diameter vertical holes facing the pier from the bridge were adopted for the blasting of the pier to overcome the influence of pier arc face on the calculation of minimum resistance line and reduce the drilling workload. Additionally, the two bridges were detonated span by span in the same direction from south to north, with an equal delay interval between two adjacent spans. At the same time, the detonation time of the new bridge is 50 ms later than that of the old bridge. To reduce the damage of blasting vibrations and ground touch vibrations, millisecond delay controlled blasting was adopted, and the direction of the minimum resistance line was deviated from the near shore protection object. Meanwhile, in order to control the flying stone, sandbags were piled on the abutment, and the blasting objects were bounded with wire meshes and covered with multilayer bamboo basketries. After detonation, the bridge collapsed span by span as expected, the vibrations and flying rocks were controlled well.

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.

Charge structure has an important impact on deep hole blasting effect with a large diameter in thick and large ore bodies. The current charge structure (24.2% air deck length) used in Bangzhong mine of Zhongkai Mining has a serious problem of post-blast impact damage, resulting in blockage, collapse or even scrapping of the latter row of holes, which seriously affects productivity. However, blindly increasing the air deck length ratio has the risk of increasing the boulder yield. Based on the actual explosives and rock parameters of the mine, a study on charging structure optimization was carried out by using the numerical simulation software LSDYNA. The commonly used air spacers were selected as the deck materials. Then, 12 charging structure solutions were designed for numerical simulation with respect to the air deck length ratio, and the relationships between the charging structure and the evaluation indexes (such as the back impact effect, boulder yield, peak particle velocity of free surface and peak effective stress) were obtained. The results show that the peak particle velocity of the free surface and the peak effective stress gradually decrease with the increase of the air deck length ratio. The back impact effect is obvious and the back row of holes may collapse when the air deck length ratio is less than or equal to 30.5%. There is a risk that the boulder yield increases when the air deck length ratio is greater than or equal to 45.3%. The optimal air deck length ratio is 44.2%. The deep hole blasting tests show that the boulder yield of the optimized charge structure is 7.1%, and the back impact effect has been effectively controlled.

In deep hole bench blasting, the classification of rock mass under different geological conditions according to its blastability is the premise for determining and optimizing blasting parameters. It is of great significance to improve blasting efficiency and effect and reduce blasting costs. Combined with the actual blasting excavation of Changtan open-pit coal mine, relevant indexes of rock mass blastability classification were obtained through on-site single-hole blasting crater tests, rock mass acoustic wave tests and laboratory rock mechanical tests. Furthermore, the blastability of stripped rock mass in Changtan open-pit coal mine was classified and evaluated based on the combination weighting (CWM) and cloud model (CM). The results show that the blastability of gray-green coarse sandstone at the 1130 platform is gradeⅢ (medium). The blastability of yellow-green medium sandstone at the 1115 platform is grade Ⅱ (more difficult to be broken by blasting). The blastability of purple-red sandy mudstone at the 1100 platform is grade Ⅰ (difficult to be broken by blasting). The blastability of purple mudstone at the 1145 platform is gradeⅢ (medium).