Key points of safety supervision in tunnel construction?

What are the key points of safety supervision in tunnel construction? Zhong Da Consulting will answer your questions below.

Tunnel construction quality is the most important guarantee to ensure safety. In the process of construction, the supervision engineer should pay close attention to quality supervision, at the same time do a good job of tunnel monitoring and measurement, master the dynamics of tunnel surrounding rock, and ensure construction safety.

I. General requirements

1. The supervision engineer shall require the construction unit to make good preparations before tunnel construction, correctly select the construction method, and review its construction organization design in combination with the actual conditions such as topography and geology; When the tunnel length is greater than 1000m, the geological advance prediction scheme and implementation rules shall be formulated as required, technical disclosure shall be made to the construction personnel, and the construction shall be arranged reasonably.

2. The supervision engineer shall regularly check the handover system established between teams and teams of the construction unit and its implementation. Handover records shall be true and complete. Including: when the shift is changed, the shift leader will explain the construction situation of the shift and related safety matters and measures to the successor in detail; The person in charge on duty at the scene and the foreman should check the handover records. Before each shift starts, the safety condition of the working face must be carefully checked, otherwise the construction may not be carried out.

3. In soft rocks or tunnels with poor geological conditions, practical construction safety measures must be formulated before construction. When adverse geological conditions are indicated in the design documents, the designated area should be detected in advance, and the construction principles of weak blasting, short excavation, strong support, early lining and roof protection should be observed.

4. During the construction, the inspection and monitoring of surrounding rock and support should be strengthened to master the deformation and displacement of surrounding rock and support. If there is any danger in the tunnel, it is necessary to set up obvious signs or assign special personnel to guard in the dangerous area, and report to the person in charge of the construction site in time to take timely measures to deal with it. When the situation is dangerous, all personnel should leave the dangerous area and report to the superior immediately.

Second, the tunnel entrance engineering safety supervision points

1. Before entering the tunnel, slope protection and drainage facilities should be well done to ensure that surface water will not endanger the safety of tunnel construction.

2. The subgrade at the entrance, slope and upward slope shall be excavated from top to bottom, and the earthwork shall be completed at one time, and the excavation personnel shall not overlap up and down. When working on a slope higher than 2m, special safety technical measures shall be formulated.

3. Before construction, the topsoil and loose dangerous stones that may collapse out of the edge and uphill on the hillside should be removed; Always check during construction, especially after rain and snow, and immediately remove loose and dangerous stones.

4. After slotted blasting, loose stones on the slope should be removed before the construction can continue; When the geology is bad, the slope should be reinforced.

5. In the process of excavation, check the slope and uphill from time to time. If there is sliding or cracking, the slope should be slowed down appropriately to ensure the stability and construction safety of the slope and uphill.

6. After the tunnel lining is completed, timely handle the damage of the slope toe above the tunnel; Slope protection measures should be taken when the slope is soft and broken.

Three, tunnel excavation, initial support construction safety supervision points

1. The supervision engineer shall ask the diggers to check whether the working face is in a safe state when they arrive at the working place. Check whether the support is firm, and remove or support any loose stones, clods or cracks.

2. In the supervision engineer's review of the construction organization design, it should be emphasized that after each part of the tunnel is excavated, the construction unit must take effective support according to the surrounding rock conditions and construction methods, except that the surrounding rock is complete and hard and there is no requirement for support in the design documents. Such as ordinary cement mortar bolt support, early strength cement mortar bolt support, early strength explosive bag bolt support, hollow grouting bolt support, shotcrete support and so on. No matter which support method is adopted, it should be:

(1) After the tunnel excavation, the anchor rod shall be installed as soon as possible, and the concrete shall be sprayed for 4~6cm, and then the anchor rod shall be installed by drilling.

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

(3) The length of the bolt exposed from the rock surface should not be greater than the thickness of the spray layer.

3. During the construction period, the supervision engineer shall, jointly with the person in charge of on-site construction and relevant personnel, regularly inspect the supporting ministries. In bad geological areas, each shift should be inspected by designated personnel at any time. When the bracket 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 leave the site before reinforcement.

4. The support in the tunnel should be supported with the excavation, and the distance between the support and the excavation surface is generally not more than 4m. In the case of gravel, severe weathering and soil tunnel, the distance between the support and the project should be shortened as much as possible.

5. When it is found that the surrounding rock of the shotcrete anchor section has great deformation or the anchor rod fails, a reinforced anchor rod should be added in this section immediately, and its length should not be less than 1.5 times of the original anchor rod length. If the sudden change or deformation of surrounding rock exceeds the design allowable value after shotcreting, steel support should be used for support.

6. When it is found that the measured data has abnormal change or mutation, the displacement value in the hole or ground is greater than the allowable displacement value, cracks appear in the hole or ground, and abnormal cracks appear in the spray layer, it should be regarded as a danger signal. When necessary, report to the superior immediately, and organize the workers to leave the site, and then continue the construction after making treatment measures.

7. With the progress of excavation in various parts of the tunnel, lining and grouting should be carried out in time, and the hole lining should be constructed as soon as possible. The hole in the unfavorable geological section must be completed first.

8. Before the construction of tunnel and underground engineering entrance section, according to the topography, engineering geology, hydrogeology, environmental conditions and construction conditions near the entrance section, all possible dangerous factors and hidden dangers and their impact on the environment should be estimated, and technical measures should be formulated to ensure the construction safety of the entrance section.

9, artificial excavation of soil tunnel, the operator must cooperate with each other, and keep the necessary safe operating distance.

10, mechanical rock drilling, appropriate uses wet rock drill or rock drill with dust, can reduce the harm of dust to operators, and use safety protection articles (such as safety helmet, mask, etc.) in accordance with the provisions. ).

1 1. When standing on the ballast pile, pay attention to the stability of the ballast pile to prevent the collapse from hurting people.

12. Before spudding, make a detailed inspection of the machines and tools used, which can not only give full play to the efficiency of machines and tools, but also ensure the construction safety. When drilling with a pneumatic drill, first check whether the fuselage, bolts, fixtures, springs and supports are in good condition, whether the pipe joint is firm and whether there is air leakage; Whether the drill pipe is straight, damaged and blocked; Whether the water supply of wet rock drill is normal and the dust removal facilities of dry rock drill are good. Do not meet the requirements, should be repaired or replaced.

13. In order to prevent electric shock accidents, the insulation devices of all parts must be inspected in detail before drilling, and necessary insulation protection articles should be worn. The rotation speed of electric drill is fast, and the rotating steel guided by hand is easy to be shot down and hurt people. It is very easy to increase the current when carrying the clamped steel drill with an electric drill, which will burn the electric drill and lead to an electric shock accident.

When drilling with an electric drill, check whether the insulation of the rubber sleeve of the handle and the device for preventing the cable from falling off are in good condition. Electric drillers must wear insulating gloves and rubber shoes. They are not allowed to guide the rotating steel drill by hand, and they are not allowed to handle the clamped drill with electric drills.

14, it is forbidden to continue drilling in the residual eye. Drugs may remain in the residual eye, and an explosion accident may occur if drilling holes in the residual eye continues.

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16. During shotcrete operation, before shotcrete starts, the shotcrete surface of surrounding rock should be inspected in detail, and dangerous stones and pumice should be thoroughly removed. Appropriate dust reduction measures should be taken according to the spraying method (wet spraying) and concrete mixture ratio to control the dust content in the air at the construction site to ensure the health of construction personnel.

17. When installing the steel support, the safety regulations on lifting and aerial work shall be observed, and appropriate small lifting machinery and tools shall be selected.

Four, tunnel blasting operation safety supervision points

1, the supervision engineer should explicitly require the construction unit to establish a unified command system for in-hole blasting, and check whether the blasting operators have received professional training and hold a blasting operation certificate.

2, supervision engineer should check the layout of blasting equipment processing room, its location should be located in a safe place at least 50m away from the mouth of the cave. It is forbidden to transform and process blasting equipment outside the processing room. When blasting equipment must be processed in long tunnel construction, the setting of safety facilities in the processing chamber should comply with the relevant provisions of the current national blasting safety regulations (GB 6722-2003).

3, supervision engineer should require full-time safety production management personnel to be present to check the blasting operation, blasting workers and blasting equipment processing personnel are strictly prohibited to wear chemical fiber clothing, in order to prevent lighting interruption when shooting, blasting workers should carry a flashlight, and it is forbidden to use open flame lighting; There is no fire.

4, blasting, supervision engineer should require full-time production safety management personnel to be present to supervise all personnel to evacuate the scene, the layout of safety signs should be eye-catching, its safe distance is:

A. the dead end is not less than 200 meters; ;

B Adjacent upper and lower tunnels shall not be less than100m;

C the distance between adjacent parallel channels, transverse channels and transverse holes shall be not less than 50m；;

D the upper section of single line shall be not less than 300m, and the whole section of single line and the upper section of double line shall be not less than 400m；;

E. When deep-hole blasting adopts double-line full-face excavation (hole depth is 3 ~ 5m), it should not be less than 500m；;

F. When the two working faces are close to being connected, the two ends should strengthen contact and unified command. When the distance between two working faces in rock roadway is close to the remaining 8 times of circulating footage, work at the other end should be stopped, personnel and machinery should be evacuated, and warning signs should be set at a safe distance.

5, supervision engineer should review the blasting technical scheme and safety disclosure records.

6. The number of shots in the hole should be clear every day, and the charging time should not be too long.

7, before charging should check whether the support near the blasting face is firm; The mud and stone powder in the hole should be blown clean; The heat of the hole just drilled is too high, so it is not allowed to charge immediately. In the case of insufficient lighting, charging and blasting are prohibited when quicksand and mud are found to be untreated, or there may be a large number of caves with water gushing. Various types of work in the tunnel cross-operate, and there are many construction machines, so the shooting times should be reduced as much as possible, and the shooting time and times should be clearly defined. In order to reduce the "misfire" caused by blasting charging tide, the interval between blasting and charging should not be too long.

8, hole blasting shall not use black powder.

9. When the spark is triggered, it is forbidden to light it with an open flame. The length of the fuse should ensure that the personnel can evacuate to a safe place after the fuse is ignited, but it should not be shorter than1.2m.. A blaster should not ignite more than 5 pieces at a time. When one person ignites more than 5 pieces or 5 people, the timing fuse should be ignited first, and the length of the timing fuse should not exceed 1/3 of the shortest fuse length.

10, after blasting, inspectors can only enter the working face after ventilation and smoke exhaust15 minutes to check whether there are any "misfires" and suspicious phenomena, and whether there are any residual explosives or detonators; Whether there are loose stones on both sides of the roof; Whether the bracket is damaged or deformed. After proper handling and confirmation, other workers can enter the working face.

1 1. When misfire is found, it must be handled by the original blasting personnel according to regulations.

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