Underwater Blasting Research Articles

Fragility analysis of high arch dam against far-field underwater blast

The security assessment of high arch dams is a significant topic that has been researched in recent years. It is troublesome to develop a security assessment for high arch dams under far-field underwater blasts because the high arch dam is a sophisticated statically indeterminate spatial shell structure, and the underwater blasting shock wave has the characteristics of a large peak value and high frequency. Hence, the fragility analysis of a 300-m-high arch dam against a far-field underwater blast based on the probabilistic method is conducted for safety evaluation with the index of downstream peak displacement (and Downstream Peak Displacement-Span ratio). The fragility analysis process of the high arch dam under the far-field underwater blast is proposed for the first time. The impact of foundation plasticity on the high arch dam under far-field underwater blast is discussed regarding dynamic response and damage patterns with the coupled acoustic-structural (CAS) method first. The damage limit states are presented based on different damage patterns and index values from enormous computational schemes. The fragility curves with different indexes of downstream peak displacement, upstream peak displacement, and damage volume ratio are also compared. The fragility curves of the high arch dam against the far-field underwater blast with different explosive distances of 50 to 200 m are established with the Artificial Neural Network method. The results demonstrate that the non-linear dynamic response and damage of the high arch dam under the far-field underwater blast are significantly influenced by the foundation plasticity, especially for vibration upstream and damage of the foundation face. The explosive situations with an explosive distance of 50–100 m and explosive weight of more than 12000 kg cause a greater threat to the security of the high arch dam with the probability of severe damage approaching 100 %. The explosive situations with an explosive distance of more than 150 m or explosive weight of less than 3000 kg have a small effect. The research results can be used as a reference when conducting safety assessments of high arch dams to blasting loads.

The Influence of Underwater Environment on the Effect of Underwater Drilling and Blasting for Bridge Pier Foundation

The Influence of Underwater Environment on the Effect of Underwater Drilling and Blasting for Bridge Pier Foundation

Research on Rapid Construction Technology of Deep Water Rock-socketed Bridge Foundation

The construction of deep water rock-socketed bridge foundation is pretty difficult and people routinely use the method of combining underwater blasting and double-wall steel box cofferdam support for construction. Combined with the site construction conditions and analysis of FEM software, through schemes comparison and technical research, the paper puts forward the construction scheme of rotary drilling pilot hole, high-pressure rotary jet grouting pile for grouting and water stopping, and cofferdam support for locking steel pipe pile, which completes the foundation construction smoothly and rapidly. By adopting the technology, the construction period is greatly shortened, the material utilization rate is improved, the construction cost is reduced, and the scheme has reference significance for foundation construction under similar environments.

Comprehensive review on principles and practices of underwater drilling and blasting, its environmental impacts, and mitigation techniques

Comprehensive review on principles and practices of underwater drilling and blasting, its environmental impacts, and mitigation techniques

Analysis of pressure surges under various flow patterns in the tunnel of an underwater rock plug blasting system using different transition process models

Abstract The pressure surge at the moment of blasting seriously threatens the safety of pipeline structures and other buildings. This article established two numerical simulation models of the hydraulic transition process and water–air two-phase flow based on the one-dimensional transient flow theory and considering the actual flow characteristics of water and air. The hydraulic characteristics and blasting parameters of the blasting system were studied under two different conditions of the tunnel with and without the pressure flow. The observed parameters of an actual blasting engineering prototype verified the accuracy of the mathematical model. The maximum pressure of pressure blasting was 2.55 times as high as hydrostatic pressure. The maximum pressure of non-pressure blasting was 1.77 times as high as hydrostatic pressure. Pressure blasting impact was 2.17 times greater than nonpressure blasting. Discrepancies between actual and simulated data for gushing and overflow heights ranged from 9 to 14%. The model can provide a reference for blasting engineering on the simulation calculation of hydraulic characteristics such as impact pressure, overflow time, and overflow of the underwater rock plug blasting system.

Voltammetric Detection of Explosive Nitroaromatic Compounds Using Boron-Doped Carbon Nanowall Electrodes

Nitroaromatic highly energetic explosive compounds were widely used during the I and II World Wars. Some of them, like 2,4,6-trinitrotoluene (TNT), are still used in military munitions or in industrial applications i.e., underwater blasting, mining, deep well or dye production. The worldwide use of nitroaromatic compounds led to widespread pollution of the environment causing a danger to living organisms due to their high toxicity and possible carcinogenicity. The most commonly used techniques for the detection of explosive nitroaromatics are high-performance liquid chromatography or high-resolution gas chromatography coupled with different detectors like mass spectrometers. Both methods require: expensive instrumentation, complex sample preparation which is crucial to analysis, and well-trained staff to perform the experiments. Therefore it is difficult to implement chromatography in the field. Electrochemical sensing is emerging as a fast, sensitive and relatively simple technique for detecting explosive materials. To date, various materials have been used as working electrodes for this purpose, however, carbon materials are particularly promising [1-2]. Among carbonaceous materials, boron-doped carbon nanowall (B:CNW) electrodes are particularly attractive for the sensitive and rapid detection of nitro-based compounds [3] due to the high content of sp2 phase, wide electrochemical working potential window (from -1.6 V to 1.2 V in 0.5 M KCl) and high values of heterogeneous electron transfer rate constant.In this work, we present electrochemical detection of chosen nitroaromatic explosive compounds like TNT on boron-doped carbon nanowall electrodes in aqueous solutions using voltammetric electrochemical techniques (differential pulse voltammetry, square-wave voltammetry, cyclic voltammetry). B:CNW electrodes were obtained using microwave plasma-assisted chemical vapour deposition in a one-step growth process. B:CNW electrode show enhanced electrocatalytic activity towards nitro moieties attached to aromatic rings, resulting in improved sensitivity toward detecting these groups. Hence, it is an attractive nanocarbon surface for nitroaromatic compound determination.

Experiments and simulation of block motion in underwater bench blasting

The blasting mechanism underlying drilling and blasting of underwater rocks, as an important component of the engineering blasting technology, has not been systematically studied. Laboratory model experiments are expensive and take a long time, while field tests fail to obtain timeous breakage and accumulation effects of underwater blasting, and may even be impossible. Considering this, a model experiment of underwater concrete bench blasting was designed, and the motion of blasted blocks was observed and evaluated with a high-speed camera. Then, numerical simulation was conducted based on Fluent and an engineering discrete element method coupling program complied using the application programming interface. Results show that the blocks form a bulge in the underwater blasting experiment under action of blast waves and expansion in the first period of bubble pulsation. Then, some blocks shrink in the first period of bubble pulsation. As the charge increases, the blast load exerts larger disturbance on the block group, resulting in significant motion of blasted blocks along the vertical direction. At the same time, the horizontal displacement of blasted blocks in the throwing direction increases.

Experiments and Fluent–Engineering Discrete Element Method-Based Numerical Analysis of Block Motion in Underwater Rock-Plug Blasting

Underwater rock-plug blasting is a special blasting technique for excavating underwater inlets. In the process of rock-plug blasting excavation, the blasting-block movement from the difference in water pressure inside and outside the tunnel is one of the key factors for successful construction. Laboratory underwater rock-plug blasting experiments were conducted using small explosive charges, and a high-speed camera was adopted to observe and study block motion. Then, numerical simulations were conducted for the model experiment based on the Fluent and Engineering Discrete Element Method (EDEM) coupling program developed using the user-defined function (UDF) interface to reveal the mechanism underpinning the penetration of underwater rock-plug blasting. The results showed that the process of block motion in underwater rock-plug blasting can be divided into two stages. In the first stage, broken blocks move to two sides along the axis of the rock plug under the blast load. A blasting crater is formed on the downstream end face of the rock plug under the effects of the free face, while the upstream end face is loosened, or blocks are ejected under the influence of the water pressure. In the second stage, blocks flow to the broken-rock pit under the effects of water scouring and gravity, and, finally, the rock plug is penetrated. The larger the head of water and the opening angle of the rock plug are, the better the penetration effect for the rock plug is. The Fluent–EDEM coupling algorithm was in good agreement with the experimental results in terms of the rock-plug blasting effect and the velocity curve of the blocks, indicating that the coupling method had a favorable effect in simulating the interaction of blocks and water during underwater rock-plug blasting. The findings are expected to promote the application and popularization of the rock-plug blasting technique and can provide a reference for rock-plug blasting in water-intake and water-diversion projects.

Influence of Water Depth on the Range of Crushed Zones and Cracked Zones for Underwater Rock Drilling and Blasting

Influence of Water Depth on the Range of Crushed Zones and Cracked Zones for Underwater Rock Drilling and Blasting

Investigation of Shock Wave Pressure Transmission Patterns and Influencing Factors Caused by Underwater Drilling Blasting

Underwater blasting technology has been widely used in inland waterway improvement projects. However, due to the particularity and complexity of underwater blasting, it is difficult to predict the transmission patterns of underwater blasting shock waves. Therefore, based on the Guoyuan Port Phase II project in Chongqing, the transmission patterns and influencing factors of underwater drilling blast shock wave pressure were investigated by field monitoring and numerical simulation. In this study, a total of 45 groups of shock wave pressures were measured, and the underwater shock wave pressure transmission formula obtained through data fitting was P = 27.39 × (Q1/3/R)1.25. Furthermore, the shock wave pressure transmission process in water was numerically simulated, and the simulation results were verified using field monitoring data. The results showed that the simulation and measured results were consistent. Finally, the influence of water depth, flow rate, and flow direction on the transmission pattern of shock wave pressure was analyzed, based on a numerical simulation method. The results showed that the more blastholes there are, the smaller the peak pressure of the shock wave. The lower the depth of blasting, the faster the decay of shock wave pressure. The flow rate has less effect on the shock wave pressure. At flow rates of 1, 2, 3, and 4 m/s in the range of 0 to 50 m, the shock wave pressure in the upstream flow decreased by 5.7%, 7.4%, 9.1%, and 10.2%, respectively, compared with that in the downstream flow. This study provides a theoretical basis for safety control of underwater drilling blasting engineering in inland waterways.

Remotely operated vehicle-based methodology for the reduction of costs and operational delays associated with rock dredging for channel deepening

Rock dredging for river channel deepening presents problems concerning the identification of whether the blasted rock is properly fragmented for the following operations and whether the excavation and disposal reach the determined project level. These issues lead to decision making that involves expensive equipment and vessel movement procedures that can result in an increase in costs and time. After characterizing and analyzing all underwater blasting and rock excavation procedures, a new methodology was developed to improve this process by applying a low-cost observation remotely operated vehicle. The tasks of the vehicle focus on monitoring and controlling some key procedures, improving the operating time and identifying operation fail points, in addition to helping to control the environmental impact. The proposed methodology was tested in São Paulo, Brazil, where the deepening of a river channel has been used to expand the waterway. The results of the tests show a 37% saving in time and a 32% saving in cost

Failure mechanism and stability analysis of bank slope deformation under the synergistic effect of heavy rainfall and blasting vibration

Underwater blasting technique is often adopted to clear away the obstructed reef and dredge-cut in the mountainous waterway dredging engineering. However, the vibration of the underwater blasting and excavation of the riverbed has a certain influence on the stability of bank slopes. Combined with the partial bank collapse phenomenon in the waterway regulation project between two dams in the Three Gorges reservoir area, the change of pore water pressure of unsaturated soil under heavy rainfall and the increase of permanent displacement of soil under blasting vibration in the reservoir area are discussed. This paper explains the weakening effect of rainfall infiltration and blasting vibration on the stability of the bank slope. By studying the law of slope failure deformation under the separate action and coupling action, it is found that rainfall infiltration promotes the increase of slope permanent displacement and the blasting vibration enlarges the infiltration area of the soil, which demonstrated the accelerated failure mechanism of the rainfall-blasting slope.

Analysis of underwater shock wave attenuation by air bubble curtain based on bubble shape

Bubble curtain is an important means to protect underwater explosion shock wave. It is of great significance to study the mechanism and technical parameters of bubble curtain for safety and application of underwater blasting. By using high-speed photography technology and video framing processing technology, indoor small underwater bubble curtain model is photographed and analyzed. It is found that the gas curtain is highly discontinuous and inhomogeneous in both the formation process and the interaction process with the underwater explosion shock wave. The gas and liquid are mixed in the air curtain area, and the interface contour is complex and diverse. Air displacement will directly affect the quality of the air bubble curtain. The larger the air displacement, the better the continuity and quality of air curtain. On this basis, consider the influence of bubble shape, interface, and gas-liquid coexistence , programming is carried out through the APDL language that comes with the LS-Dyna finite element software. By setting the variation range of bubble diameter and the minimum difference between bubble diameters, a certain number of bubbles of different diameters are randomly placed to simulate the distribution of bubbles in the real air curtain. The air curtain quality under different gas source pressure can be simulated by changing the number of bubbles in the set air curtain area. It is found that this method can more truly reflect the protection mechanism of air curtain in the protection process of shock wave. Comparing the protective effect of air curtain with different bubble numbers on the same shock wave, it shows that with the increase of bubble number in unit area, the protective effect is more obvious. However, when the number of bubbles reaches a certain number, the overall continuity and stability of the air curtain are basically fixed, and the protection effect tends to be stable.

Study on the Propagation Law of Water Hammer Wave in Underwater Blasting and the Reducing Effect of Air Curtain on Water Hammer Wave

The harmful effects (water hammer wave, flying stone, and broken quality of concrete) produced in the process of underwater drilling and blasting are the key factors affecting the safety of underwater drilling and blasting. In fact, the harm caused by the water hammer wave is the most significant. As a consequence, it is of great significance to study the propagation law of water hammer waves. Based on the background of the cofferdam demolition project at the inlet section of Shibishan Central Canal in Ningguo City, China, a three-dimensional numerical model was established based on Coupled Eulerian–Lagrangian (CEL) method. Besides, the propagation law of water hammer waves at different water depths with different millisecond times was studied. Meanwhile, the reduction effect of the water hammer wave at different positions of the bubble curtain was analyzed. The results showed that, in the direction of the minimum resistance line of the charge, the attenuation law of the water hammer wave is accorded with the Cole formula and attenuated exponentially. The attenuation speed of the water hammer wave increased at first and then decreased with the increase of the millisecond time. In addition, the attenuation rate of the peak pressure was the fastest when the millisecond interval 30 ms was used. The attenuation of the water hammer wave at different water depths decreased at first and then decreased with the increase of water depth. The attenuation law of the water hammer wave decreased linearly with the increase of the distance between the bubble curtain and the charge. The research results can provide particular guiding significance for similar on-site construction.

A Novel Denoising Model of Underwater Drilling and Blasting Vibration Signal Based on CEEMDAN

In underwater drilling and blasting engineering, the blasting vibration signal is mixed with a mass of noises due to the complexity of monitoring environment, the error of monitoring sensors and the reflection of propagation medium. In order to accurately obtain the characteristics of vibration signal, a novel denoising model is established. The complete ensemble empirical mode decomposition with adaptive noise is used to decompose the original signal, and the objective function of the filtering algorithm is used to obtain the optimal denoising signal. The results indicate that the model can not only successfully remove the high-frequency noise but also has no effect on the low-frequency signal components, which verifies the reliability and validity of the denoising model.

Piezoelectric-based damage-depth monitoring method for underwater energy-relief blasting technique

Owing to the complex geological conditions and strict excavation shaping and damage control requirements in some underwater engineering applications, the development of a suitable blasting excavation technique has become one of the most difficult technical challenges. The application of Energy-Relief Blasting (ERB) technology to underwater drilling and blasting was first proposed, and a new non-destructive damage assessment method for underwater blasting was also developed. To verify the feasibility of ERB in underwater blasting, two comparative underwater drilling blasting experiments at a depth of 40 m were performed in a water-medium explosion vessel. A pair of piezoelectric ceramic transducers as actuators and sensors to emit and receive the acoustic wave signals, respectively, and thus evaluate the blasting damage induced in concrete specimens. A damage index was defined based on the processed data. The experimental results demonstrated that the ERB technique can effectively control blasting-induced damage in the bedrock. For the specimen with conventional blasting, the depth of damage index greater than 92% is 16 cm, while that of energy-relief technique is only 12 cm, which is 25% less than that of conventional blasting. The experimental results also showed that the active sensing method based on piezoelectric transducers combined with the signal processing method based on the transmitted energy can be used to monitor and quantify the damage induced in the rock mass by underwater drilling blasting.

Blast Vibration Control in A Hydropower Station for the Safety of Adjacent Structure

The transverse cofferdam in Xiangjiaba hydropower station was a water retaining concrete structure with a length of 126 m, a width of 12 m, and a height of 25.2 m, consisting of masonry, plain concrete structure (PC), and roller compacted concrete (RCC), which had to be demolished by blasting after the dam was built. There were many precise instruments nearby the cofferdam which had strict restrictions on blasting vibration. Therefore, the cofferdam was divided into six blasting regions, including land blasting and underwater blasting. Blasting parameters and blasting network structure were accurately designed and continuously optimized through blast-induced vibration test results. At nine measurement points in different locations, 57 blast vibration data were recorded. Consequently, 1386 holes with an explosive weight of 9641.3 kg were detonated in land blasting. The highest levels of vibration were recorded as 8.74 cm/s in the desilting tunnel on the right of the cofferdam. The explosives up to 11887.7 kg were detonated in an underwater blasting. According to the analysis of the law of vibration attenuation, the blast vibration value was reduced to 7.65 cm/s. The results showed that the research on the attenuation law of blasting vibration can effectively increase the charge weight per delay and control the blast-induced vibration. Consequently, the peak particle velocity (PPV) of underwater blasting could be predicted by analyzing the PPV of land blasting in same structure, which provided the basis for the design of underwater blasting parameters. A reliable method for cofferdam demolition in hydropower station was proposed, which provided a reference for similar projects.

Influence of free face numbers on energy distribution characteristics of blast vibration signal in underwater drilling blasting

Aiming to the problem of free face not only affect the blasting effects but also the blasting vibration affects, an analytical method of exploring the free face’ influences of the blasting vibration and the attenuation law of seismic wave is proposed. Taking the field monitoring data of underwater blasting seismic wave between the river reach of the Three Gorges Dam and Gezhouba Dam as the study object, utilize the wavelet analysis and decompose method to research the blasting vibration signal’s total energy and energy distribution characteristics in variety of frequency band on different free face. The results indicated that underwater drilling blasting vibration has the characteristic of low frequency, short duration and fast attenuation. Most of the energy of the explosion will be consumed as seismic energy in the slotted blasting due to the restricted of a single free face. However, after the subsequent excavation blasting, the free face number increases but the total energy of blasting vibration and PPV decreases. Therefore, in addition to the usual seismic mitigation measures of underwater drilling and blasting, the number of free faces can be increased to achieve the effect of shock absorption control without reducing section charge.

Analysis of fracture mechanism for surrounding rock hole based on water-filled blasting

The principles of fracture development during underwater blasting are examined based on explosion and impact dynamics, fluid dynamics, fracture dynamics, and field testing. The research reveals that the fracturing of the surrounding rock during underwater blasting is due to the combined action of shock and stress waves for the initial rock breakage and subsequent water expansion. The fracture development model for the surrounding rock of a drilling hole during underwater blasting is established. The rock fracturing range under the combined action of shock and stress waves is developed, as well as the fracture propagation rules after the wedging of the water medium into the fractures. Finally, the results of deep-hole underwater blasting tests on large rocks confirm the efficient utilization of explosive in the hole to improve the safety conditions. Accordingly, safe and static rock breaking under the detonation of high-effect explosive can be achieved. In addition, super-dynamic loading from the explosions and static loading from the water medium in the hole can be adequately combined for rock breaking.

Discharging Compacted Sediment by Underwater Blasting in Conjunction with a Desilting Tunnel in the Tseng-Wen Reservoir of Taiwan

AbstractSediments transported by heavy rainfall result from frequent typhoons in the Tseng-Wen reservoir, which now comprise one-third of the capacity of the reservoir. Yearly increases of 6.56 mi...