Safety protection of the hottest underground engin

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Safety protection of underground engineering construction

in order to protect the health and safety of construction personnel, the requirements for underground construction environment and protective measures for harmful factors. Mainly the requirements for harmful gases, dust, noise and lighting

harmful gases are mainly produced by incomplete decomposition of explosives during excavation blasting and incomplete combustion during operation of internal combustion machinery. There will also be natural gas (such as biogas) or sulfur-containing harmful gas in gas bearing sections or sulfide bearing seams. According to the regulations of China's "safety technical work regulations for water conservancy and hydropower construction and installation" (sd267-88), during the construction of underground projects, each person is supplied with 3M fresh air per minute. China stipulates in the technical code for construction of underground excavation engineering of hydraulic structures (dl/tso-1999) that the oxygen in the tunnel shall not be less than 20% by volume during the construction process

to eliminate harmful gases To supply fresh air, natural ventilation or mechanical ventilation is usually used to purify the air in underground engineering construction a

(L) natural ventilation. Ventilation depends on air convection inside and outside the tunnel. ① In the short tunnel where no harmful gas is produced in the rock stratum, the air can be purified by inlet air. ② When the tunnel section is large and divisional excavation is adopted, the pilot tunnel and pilot shaft can be penetrated first to form convective ventilation. ③ When excavating long tunnels or underground power houses, channels such as parallel adits and permanent shaft tunnels can be used to circulate the air flow with the shaft tunnels

natural ventilation has the advantages of easy air supply, large air supply capacity and low cost

(2) mechanical ventilation. Ventilation methods such as air duct, tunnel and air duct. Air duct ventilation also includes pressure type, extraction type and mixed type. Self pressure and manual pressure are used to press fresh air to the working face through the air duct Dilute and purify the harmful gas, which has little impact on blasting, 3 Adjust the pressure and injection volume to produce finished products with satisfactory appearance, but the dirty air is discharged from the full section of the tunnel, affecting other types of work in the tunnel, and the smoke dispersion time increases with the length of the tunnel. ② The extraction type is that the fan pulls out the dirty air flow of the working face along the air duct, and the white tunnel supplies fresh air in the full section. The smoke exhaust speed is fast, but the end of the air duct is relatively close to the working face, which is easy to be damaged by blasting. ③ In the mixed type, one fan is used to press fresh air, and the value of the other fan is an unknown number to suck out the dirty air flow of the working face along the air duct. It has strong ventilation capacity and good sanitary conditions, but it requires two sets of divination equipment, and the operation cost is high

the main sources of dust are primary dust generated by construction operations such as rock drilling, blasting, slag discharge or secondary crushing, and some dust that has fallen and is disturbed by other factors (such as wind flow, air shock wave during blasting, vehicle operation, personnel activities, etc.) and flies again. The dust commonly seen in underground engineering construction is mostly dust particles with particle size of 0.25-10 BYM, which can settle at an equal velocity. The main object of dust prevention is respiratory dust greater than 5 BYM, and this dust generated by rock drilling accounts for about 85%. Therefore, the main dust prevention measures are for rock drilling operations. Usually, wet rock drilling is used in underground engineering excavation, that is, when drilling, water is sprayed from the rock drill to reduce dust, but domestic manufacturers "creatively" use it to reduce costs and cooperate with other dust prevention measures For example, after blasting, spray reduces the dust content suspended in the air; Set a perforated water pipe near the working face to pass water to form a water curtain; Wash the rock wall dust with pressure water; Drench the slag with water when loading and discharging the slag, as well as personal protective equipment such as dust cover, compressed air respirator, dust helmet, etc

in addition to the dust generated during the excavation of underground works, cement dust is also one of the dust sources of the working face, which brings us rich profits and returns during the shotcrete operation. The dust particles of these dust sources are difficult to settle. Generally, measures such as improving the injection process, controlling the working air pressure, and improving the operation technology are adopted to solve the problem. If conditions permit, a cyclone dust collector can be set

noise is generated by the operation, vibration, friction, impact and airflow disturbance of construction machinery such as rock drilling, slag removal and ventilation. It is also an important pollution source of the working face, and its harm is enough to reduce work efficiency, damage hearing and induce diseases. Generally, the noise at the working face of underground engineering construction is required to be no more than 85dB. When it exceeds 90dB, protective or silencing measures should be taken, otherwise the exposure time to noise should be reduced

lighting underground engineering construction usually uses 36V or 24V voltage lighting or 220V voltage projection lamp for lighting. In the tunnel forming section of long tunnels, high-voltage insulated cables are often used to introduce 10-6kv voltage to set up transformer stations at appropriate places. The power supply line in the tunnel is required to have good insulation performance The lighting line and power line are erected separately

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