Safety requirements for the hottest excavation ope

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Safety requirements for excavation operation

1. Factors affecting the safety of excavation operation

when the tunnel passes through the rock stratum with developed joints and easy to be weathered, the existence of various special geological phenomena will bring difficulties and unsafe factors to the construction

appropriate excavation methods and construction processes should be selected according to different geological conditions, such as drilling and blasting method, mechanical excavation method, manual and mechanical mixed excavation method, etc. if the method is improperly selected, the risk degree in construction will increase

during the construction process, strengthen management, scientifically organize and reasonably arrange the construction procedures, such as the rational use of machines and tools, the management of blasting equipment, etc. Poor management is an important factor affecting the safety of excavation operations

2. General safety requirements for excavation operation:

⑴ the size of the construction part shall be mastered according to the design position, center line, level, geology and other conditions, as well as the possible settlement and construction error, so as to ensure that the excavation and lining section meet the design requirements. At the same time, the cyclic footage shall be determined according to the selected construction method and equipped excavation method and steps to meet the energy-saving needs of users to the greatest extent, So that all processes can cooperate with each other

⑵ after arriving at the work site, the staff should first check the safety state of the working face, and carefully check the stability of the support and surrounding rock. Loose stones or cracks should be removed or supported, as well as during the construction process

⑶ special personnel should be arranged to find the roof slab. Do not pry the roof hard. Some manufacturers can only output the maximum force value, only knock it down or pry it gently, so as to prevent the surrounding rock from losing its self-supporting arch capacity and causing collapse

⑷ adopt full face excavation for surrounding rock above grade III; The front bench excavation method is adopted for grade IV and V surrounding rocks, and the bench length must be less than the tunnel span. It is strictly forbidden to advance the construction of half section without falling to the bottom and sealing in time

(5) shotcreting must be carried out in time at the places prone to collapse and rock fall in the tunnel, so as to block the rock joints and form a rock bearing arch, and strictly control the quality of initial support

⑥ the construction lighting voltage should adopt the safety extra low voltage below 36V

3. Safety requirements for divisional excavation

⑴ heading excavation

heading excavation is the leading process of tunnel divisional excavation. Multiple cycles should be adopted to select the optimal blast hole depth, improve the blasting effect, speed up the excavation progress, increase the working face of subsequent processes, and improve the construction speed. However, it is generally not appropriate to lead too much in construction in the thinner area with poor geological recovery materials to prevent collapse

according to geological conditions, support methods, power, transportation, ventilation, drainage and other conditions, the heading section is selected on the premise of ensuring construction safety

pay attention to the angle of the bottom plate eye during the excavation of the lower heading, and pay more attention to the construction of the downhill tunnel to prevent raising the bottom plate

⑵ expand excavation by sections

after reloading the mobile phone software by sections, copy the documents of backup data to the new installation path for replacement, and expand excavation. Because it is carried out under empty conditions, it is most likely to cause over excavation, under excavation and collapse. In order to prevent over excavation and under excavation, measures such as strengthening construction survey, side drilling and smooth blasting can be taken: under excavation is most likely to occur within LM above the arch foot, resulting in insufficient lining thickness, and the excavation size should be strictly controlled; When the upward layered expansion construction is adopted, the section is not easy to control, so the construction survey should be strengthened, and the section should be checked before mucking. When the surrounding rock pressure is high, the support should closely cooperate to prevent collapse

⑶ inverted arch excavation

for tunnels with inverted arches, the excavation of inverted arches is generally carried out by section jumping method. It is not allowed to leave the excavation for a long distance and open the excavation with large machinery such as scraper, so as to avoid tunnel collapse

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