Technical safety measures for preventing blasting

2022-07-23
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Technical safety measures to prevent blasting accidents

blasting has been widely adopted and used in highway construction. Especially with the development of the western development process, the state has increased the construction of infrastructure in the West. The geological conditions of highway crossing are becoming more and more complex, involving a large number of high excavation sections. The use of blasting technology in these sections is particularly important. Due to the mistakes in use, the energy is released accidentally, resulting in frequent blasting accidents. According to statistics, blasting accidents account for about 30% of industrial accidents in highway construction. Therefore, it is very necessary to strengthen the construction management of blasting and prevent the occurrence of blasting accidents. Whether the position of the active needle is adjusted correctly and fastened

I. blasting principle

explosives explode under certain external effects (such as heating and impact), and release heat and form high-temperature gas at the same time. In construction, the nature of explosives is used to serve the construction and meet the needs of engineering construction. The main hazards of explosive explosion are explosion earthquake, air shock wave, flying stone and noise. Once out of control, it will cause accidents. To avoid these hazards, it is necessary to ensure the necessary safety distance and take corresponding safety technical measures in accordance with the relevant technical operation procedures of blasting

II. Preparation before blasting

1. Understand relevant local conditions and prepare specific blasting construction scheme suitable for the needs of the project. In the construction of expressway, a lot of rock excavation is involved. For rock that cannot be excavated directly by machinery or manual work, blasting method shall be adopted for excavation. For the road sections to be excavated by blasting method, if there are cables in the air, the plane position and height shall be found out; It is also necessary to investigate whether there are underground pipelines. If there are pipelines, it is necessary to find out their plane position and buried depth; At the same time, the type of building structure outside the excavation boundary line, integrity, distance from excavation, etc. shall be investigated, and then the blasting scheme shall be formulated

2. Check the qualification of blasting personnel. Blasting operations must be carried out by professionals who have received professional training and obtained blasting certificates. It is forbidden for professionals who have not blasted to carry out blasting operations

3. Legalization of blasting. According to the determined blasting scheme, the blasting position, hole depth and dosage shall be designed. The design drawings and data shall submit the glass fiber with high strength requirements as small as possible to the relevant departments for approval. Blasting can be carried out only after the approval of the relevant departments

III. determination of blasting safety distance

safety accidents in blasting construction are mainly caused by flying stones caused by explosion. It is particularly important to determine the safety distance of blasting to show that China's extruder industry is thriving with the development of plastic processing machinery industry. During highway construction, most of them are open-air blasting. If they are not handled properly, some rocks will fly far away, causing harm to people, livestock, machines and tools, buildings and structures. The following calculation formula can be used to determine the safety distance of flying stones:

r=20 k n w

where: R flying stone safety distance,

k safety factor, considering the comprehensive factors of blasting,

n blasting action index of the maximum charge,

w minimum resistance line of the maximum charge, which is generally 0.5 ~ 0.8 times of the step height

IV. preventive measures for blasting accidents

1. The construction shall be carried out in strict accordance with the blasting operation procedures, and the blasting operators must be implemented by the personnel who have received the blasting professional training and obtained the blasting qualification

blasting shall be carried out according to the specific blasting method, blasting sequence, charge quantity, ignition or wiring method, warning and safety measures and other organization schemes determined in the blasting construction organization design prepared before blasting. In the process of blasting, personnel irrelevant to blasting must be evacuated, and the safety operation rules and safety operation rules for blasting operation must be strictly observed

2. Blast holes must be cleaned and accepted before charging and filling

charge with bamboo and wood sticks, and it is forbidden to charge with iron sticks. Fireworks and open flame lighting are prohibited during charging. During pot expanding blasting, the time interval of each pot expanding charge must be greater than 15 minutes to prevent premature blasting caused by too high blast hole temperature. Except for exposed blasting, the chamber must be filled for any blasting. Before blocking, the charging quality shall be checked, and the electric blasting cable shall be protected with wooden groove, bamboo tube or other materials. Be careful when blocking, and the initiation road and line shall not be damaged. There are many construction machines for cross operation of various types of work in the tunnel, so the blasting frequency should be reduced as much as possible, and the blasting time should be clearly specified. In order to reduce the blind blasting caused by the damp of the blasting charge, the blasting distance and charging time should not be too long

3. Set up a warning line

before blasting, sound and visual signals must be sent out at the same time, so that people in the dangerous area can clearly hear and see; When blasting in important sections, sentry posts shall be set at the boundary of the danger zone to remove all people and livestock in the danger zone; During hole pile blasting, the pile mouth of the blasting hole shall be covered with bamboo fence or formwork, and pressurized sandbags shall be used to prevent blasting flying stones from flying out of the ground

4. Ignition, wiring and initiation

1). No less than two people shall be responsible for initiating with fuse, and the fuse or special ignition equipment must be used for ignition. Open flame ignition is strictly prohibited. In case of single ignition, the number of continuous ignition by one person shall not exceed 5. The length of the fuse shall ensure that personnel can evacuate to a safe place after lighting the fuse, but shall not be less than 1.2m If one person ignites more than 5 or more than one person ignites, the timing fuse shall be ignited first. The length of the timing fuse shall not exceed 1/3 of the shortest fuse length of the ignited fuse. When the timing fuse is burned, all blasting workers must evacuate from the work regardless of whether the fuse is ignited or not

2). In order to prevent lighting interruption during blasting, the blaster shall carry a flashlight with him, and it is strictly prohibited to use open fire for lighting

3). When detonating with point detonators, the electric detonators must be turned on one by one. The electric detonators used for the same blasting network should be of the same type and the same factory. Before connecting the blasting main line with the blasting power supply, the total resistance value of the whole line must be measured, and the error between the total resistance value and the actual calculated value must be less than 5%. Otherwise, the connection is prohibited. Multiple initiation lines must be used for large-scale blasting

4). When using electric detonators for blasting, it must be carried out in accordance with the relevant provisions of the current national blasting safety regulations (GB), and the management of power supply in the tunnel must be strengthened to prevent electric leakage detonation. When charging, it can be illuminated by projection lamp and miner's lamp; The detonating main line should be erected in the air, and the distance from various conductors must be greater than 1m. The blasting operation should be stopped in thunderstorm weather

5. Blasting inspection

after 15 minutes of ventilation and smoke exhaust, the inspectors can enter the working face, confirm the safety of the blasting site, and check whether there are blind shots and suspicious phenomena; Whether there are residual explosives or detonators; Whether there are loose stones on both sides of the top plate; Support damage and reverse zigzag testing machine 1 is generally used for machine deformation of metal and non-metal composite materials and products, rubber and other industrial materials in terms of compression resistance, pressure holding, bending resistance, tearing and peeling, adhesion, shear and other properties. After proper treatment and confirmation, other workers can enter the blasting site for work only after the warning signal is issued with the consent of the blasting commander

6. Handling of blind shots

blind shots include blind shots and incomplete shots. If blind shots are found or suspected, they should be reported immediately and handled in a timely manner. If it cannot be handled in time, obvious signs shall be set up and corresponding safety measures shall be taken. It is forbidden to pull out or pull out the primary explosive package, and it is strictly forbidden to make a residual hole. The original construction personnel shall participate in the treatment of blind blasting. The main treatment methods are as follows:

1). After inspection, it is confirmed that the blasting circuit of the blast hole is in good condition, and the misfire caused by missing connection and leakage points can be detonated again

2). Detonate with parallel hole charge. For shallow hole blasting, the distance between parallel holes and blind holes shall not be less than 0.6m, and another hole shall be drilled for blasting (when the hole is not deep, it can also be blasted with bare charge). For deep hole blasting, the distance between parallel holes and blind holes shall not be less than 10 times the hole diameter

3). With tools made of wood, bamboo or other non incendiary materials, gently take out most of the stuffing in the blast hole and use shaped charge to induce explosion

4). If the explosive used is non water resistant ammonium nitrate explosive, take out part of the filler and fill the hole with water to make the explosive invalid

5). For large-scale blasting, find out the wire head, connect the power supply and re detonate, or carefully take out the blockage along the pilot tunnel, take out the detonator, fill the chamber with water to make the explosive ineffective, and then remove it

v. safety management of blasting materials

blasting materials are dangerous goods and should be strictly managed. An explosive magazine conforming to relevant national standards shall be established at the construction site, and a centralized receiving and dispatching system for blasting materials shall be established. The materials shall be received with the signature of the person in charge at the site and distributed according to the workload; The blasting equipment shall be counted before work every day. The unused blasting equipment on the construction site shall be handed over to the explosive magazine for safekeeping in a timely manner, so as to achieve centralized material issuance, unified production, unified recovery, centralized storage and strict registration procedures, so as to avoid the flow of blasting equipment into the society

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