Key points for tunnel project construction safety supervision?

What are the specific key points of tunnel project construction safety supervision? Zhongda Consulting will answer them below.

The quality of tunnel construction is the most important guarantee for safety. During the construction process, supervision engineers must pay close attention to quality supervision, and at the same time do a good job in tunnel monitoring and measurement to understand the dynamics of the surrounding rock of the tunnel to ensure construction safety.

1. General requirements

1. The supervision engineer should require the construction unit to make pre-construction preparations before tunnel construction, correctly select construction methods, and combine topography, geology and other actual conditions According to the situation, the construction organization design prepared by them shall be reviewed; when the tunnel length is greater than 1000m, it shall be required to formulate an advanced geological forecast plan and implementation details, provide technical explanations to the construction personnel, and reasonably arrange the construction.

2. Supervision engineers should regularly check the handover system and implementation status established between each team of the construction unit. Shift handover records should be true and complete. Including: at the time of shift handover, the successor will explain the construction status of the team and related safety matters and measures in detail to the successor; records of the construction site duty person in charge and foremen inspecting the shift handover situation. Construction will not be allowed if the safety conditions of the working surface are not carefully checked before each shift starts.

3. In tunnels with soft rock or poor geology, practical construction safety measures must be formulated before construction. If the design document specifies bad geology, advance detection should be carried out in the designated area, and weak blasting should be followed. , short excavation, strong support, early lining, first roof protection and other small cycle construction principles.

4. During construction, inspection and monitoring of surrounding rock and supports should be strengthened to understand the deformation and displacement of surrounding rocks and supports. If a dangerous situation is discovered in the tunnel, clear signs must be set up in the dangerous area or a special person must be assigned to guard it, and the person in charge of the construction site should be reported quickly, and measures should be taken to deal with it in a timely manner. When the situation is dangerous, all staff should be evacuated from the dangerous area and reported immediately to superiors. .

2. Key points for safety supervision of tunnel entrance projects

1. Before entering the tunnel, slope protection and drainage facilities should be in place to ensure that surface water does not endanger tunnel construction safety.

2. The tunnel entrance roadbed, side slopes, and incline sections should be excavated from top to bottom, and the earthwork should be completed at one time. Excavators are not allowed to overlap up and down operations. Special safety technical measures should be formulated when working on slopes higher than 2m.

3. Topsoil and loose and dangerous rocks on the slopes and slopes that may collapse should be removed before starting construction; inspections should be carried out frequently during construction, especially after rain and snow. Loose and dangerous rocks must be removed immediately if found. .

4. After trough blasting, loose stones on the side slopes should be removed before construction can continue; when the geology is poor, reinforcement measures should be taken on the side slopes.

5. Side slopes and inclines should be checked at any time during excavation. If there is sliding, cracking, etc., the slope should be appropriately slowed down to ensure the stability of the side slopes and inclines and construction safety.

6. After the lining of the cave door is completed, promptly deal with the damage to the foot of the upward slope above the cave door; when the ground on the side slope is soft and broken, slope protection measures should be taken.

3. Key points for safety supervision of tunnel excavation and initial support construction

1. Supervision engineers should require excavation personnel to first check whether the working surface is in a safe condition when they arrive at the work site. Check in detail whether the support is firm. If there are loose stones, soil blocks or cracks, they should be removed or supported.

2. During the review of the construction organization design by the supervision engineer, it should be emphasized that after the excavation of each part of the tunnel, except for those where the surrounding rock is intact and hard and does not require support as specified in the design document, the construction unit must follow the instructions of the surrounding rock. Adopt effective support according to the conditions and construction methods. For example, ordinary cement mortar anchor support, early-strength cement mortar anchor support, early-strength chemical package anchor support, hollow grouting anchor support, shotcrete support, etc. are used. No matter which method of support is used, the following should be done:

(1) After the tunnel is excavated, anchors should be installed as soon as possible, and concrete should be sprayed 4 to 6cm initially, and then drilled to install anchors. Rod.

(2) The hole position, hole diameter, hole depth and layout of the anchor rod should meet the design requirements.

(3) The length of the rock bolt body exposed on the rock surface should not be greater than the thickness of the shotcrete layer.

3. During the construction period, the supervision engineer should work with the on-site construction leader and relevant personnel to conduct regular inspections of various support departments.

In poor geological areas, each shift should be required to have a dedicated person inspect at any time. When the support is found to be deformed or damaged, it should be repaired and reinforced immediately. When the deformation or damage is serious, the construction personnel should be evacuated from the site first, and then reinforced.

4. The support in the tunnel should be supported as the excavation is carried out. The distance from the support to the excavation surface is generally no more than 4m. In case of broken stone, severe weathering or soil tunnel, the distance should be shortened as much as possible. The distance from support to work.

5. When it is found that the surrounding rock in the section that has been blasted has significant deformation or the anchor fails, additional reinforced anchors should be immediately added to the section, and the length should not be less than 1.5 times the length of the original anchor. times. If after blasting, it is found that the surrounding rock suddenly mutates or the deformation of the surrounding rock exceeds the design allowable value, steel supports should be used for support.

6. When abnormal changes or mutations are found in the measurement data, the displacement value in the cave or on the surface is greater than the allowable displacement value, cracks appear in the cave or on the ground, and abnormal cracks appear in the spray layer, it should be regarded as Danger signals must be reported immediately to superiors and the workers must be organized to evacuate the site if necessary. Construction can only continue after handling measures are formulated.

7. As the excavation work of each part of the tunnel progresses, lining and grouting should be carried out in a timely manner. The lining of the tunnel door must be constructed as early as possible, and the entrance of the tunnel in poor geological areas must be completed first.

8. Before constructing the entrance section of tunnels and underground projects, various possible risk factors and hidden dangers must be estimated based on the terrain, engineering geology, hydrogeology, environmental conditions and construction conditions near the entrance. , as well as the impact on the environment, etc., and technical measures to ensure the construction safety of the tunnel entrance section are formulated.

9. When manually excavating soil tunnels, operators must cooperate with each other and maintain the necessary safe operating distance.

10. When mechanically drilling rock, it is advisable to use a wet rock drill or a rock drill with a dust collector to reduce the harm of dust to operators, and use safety protective equipment (such as safety helmets, masks, etc.) in accordance with regulations. .

11. When working on a pile of ballast, attention should be paid to the stability of the pile to prevent it from falling and injuring people.

12. Detailed inspection of the machine tools used before drilling can not only give full play to the efficiency of the machine tools, but also ensure construction safety. When drilling holes with a pneumatic drill, you should first check the fuselage, bolts, ferrules, springs and Check whether the bracket is normal and intact, whether the pipe joints are firm, and whether there is air leakage; whether the drill pipe is not straight, damaged, or blocked in the hole; whether the water supply of the wet rock drill is normal, and whether the dust collection facilities of the dry rock drill are good. Those that do not meet the requirements should be repaired or replaced.

13. In order to prevent electric shock accidents, the insulation devices of each part must be carefully checked before drilling, and necessary insulation protective equipment must be worn. The electric drill rotates quickly, and the rotating steel guided by hand is easily injured by being knocked down. Using an electric drill to handle a clamped steel drill can easily increase the current and burn out the drill, resulting in an electric shock accident.

When drilling holes with an electric drill, check whether the insulation of the handle rubber sleeve and the device to prevent the cable from falling off are in good condition. Electric drill workers must wear insulating gloves on their hands and insulating rubber shoes on their feet. They are not allowed to guide the rotating steel drill with their hands, and are not allowed to use an electric drill to handle a clamped drill bit.

14. It is strictly forbidden to continue drilling in the residual eye. There may be residual medicine left in the residual hole, and continuing to drill holes in the residual hole may cause an explosion.

15. When the drilling rig enters the hole, there must be a special person to direct it, and the road conditions and safety limits must be carefully checked. Its walking speed shall not exceed 25m/Mmin. When the drilling rig is walking or waiting to avoid, the drilling rig should be moved The equipment and equipment are stowed to their placement positions. They must not tilt after being in place. The wheels should be braked and the pillars should be lowered to prevent movement.

16. In the spraying concrete operation, before the spraying starts, the condition of the sprayed surface of the surrounding rock should be carefully checked, and dangerous stones and pumice should be thoroughly cleaned. The spraying method (wet spraying) and concrete mix ratio should be etc., adopt appropriate dust reduction measures to control the dust content in the air at the construction site to ensure the health of construction workers.

17. When installing steel supports, safety rules regarding lifting and working at heights should be followed, and appropriate small machines should be used for hoisting.

IV. Key points for safety supervision of tunnel blasting operations

1. The supervision engineer should clearly require the construction unit to establish a unified command system for blasting in the tunnel, and check whether the blasting operators have received professional training and maintained Have blasting operation certificate.

2. The supervision engineer should check the layout of the blasting equipment processing room, and its location should be at a safe place at least 50m away from the opening. It is strictly prohibited to modify and process blasting equipment in locations other than the processing room.

When blasting equipment must be processed inside the tunnel during long tunnel construction, the safety facilities in the processing chamber should comply with the relevant provisions of the country's current "Blasting Safety Regulations" (GB 6722-2003).

3. The supervision engineer should require full-time production safety management personnel to inspect the blasting operations. Blasting operations and blasting equipment processing personnel are strictly prohibited from wearing chemical fiber clothing. In order to prevent lighting interruption during firing, blasters should carry flashlights with them. , it is strictly forbidden to use open flames for lighting; it is strictly forbidden to use fire.

4. When blasting is carried out, the supervision engineer should require full-time production safety management personnel to be on site to supervise the evacuation of all personnel from the site. The layout of safety signs should be eye-catching, and the safe distance is:

a. The length of a single-ended tunnel shall not be less than 200m;

b. The length of adjacent upper and lower tunnels shall not be less than 100m;

c. The length of adjacent parallel passages, cross passages and cross holes shall not be less than 100m. Less than 50m;

d. The half section of the single line is not less than 300m, the full section of the single line and the half section of the double line are not less than 400m;

e. The full section of the double line is open When digging for deep hole blasting (hole depth 3 to 5m), the distance should be no less than 500m;

f. When the two working surfaces are close to being connected, the two ends should strengthen contact and unified command. When the distance between the two working faces of a rock tunnel approaches 8 times the remaining cyclic footage, work at the other end should be stopped, personnel and machinery should be removed, and warning signs should be set up at a safe distance.

5. The supervision engineer should review the detonation technical plan and safety disclosure records.

6. There should be clear regulations on the number of shots fired in the cave every day, and the time between charging and firing should not be too long.

7. Before charging, check whether the support near the blasting working surface is firm; the mud and stone powder in the blasthole should be blown clean; the heat of the newly drilled blasthole is too high, and charging should not be carried out immediately. If so, When there is insufficient lighting, it is found that quicksand and mud have not been properly dealt with, or there may be a large amount of water gushing from the cave, it is strictly prohibited to charge and blast. In the tunnel, various types of work are intertwined and there are many construction machines, so the number of shot blasts should be minimized, and the time and number of shot blasts should be clearly defined. In order to reduce "blind firing" caused by the tide of blasting charges, the time between blasting and charging should not be too long.

8. Black gunpowder is not allowed for blasting inside the cave.

9. Open flame ignition is strictly prohibited when sparks are detonated. The length of the fuse should ensure that personnel can evacuate to a safe place after lighting the fuse, but it should not be shorter than 1.2m. One blaster can ignite at a time The number of fuses should not exceed 5. If one person fires more than 5 fuses or multiple people light the fuses, the timing fuse should be lit first, and the length of the timing fuse should not exceed the shortest fuse among the fuses to be lit. 1/3 of the length. When the timing fuse is burned out, regardless of whether the fuse is lit or not, the blasters must evacuate the working surface.

10. After 15 minutes of ventilation and smoke exhaust after blasting, inspectors can enter the working surface to check whether there are any "blind guns" and suspicious phenomena, whether there are residual explosives or detonators; whether there are any leaks on the two sides of the roof Loose stones; check whether the support is damaged or deformed. Only after proper handling and confirmation can other staff enter the work surface.

11. When a blind gun is discovered, it must be handled by the original explosives personnel in accordance with regulations.

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