Special processes and critical processes that require road and bridge tunnels

Well written! 90% of bosses wouldn't do that!

Answers]: a, b, c, d

Textbook, pp. 283-287

The key processes of tunnel engineering are smooth blasting, tunnel support, surrounding rock reinforcement and cracked tunnel lining.

Hello dear, 1. Before entering the hole, the side and slope construction (including drainage, electricity and other preparations); 2. Advance the stool of the jujube slag of the large pipe shed 3, measure and position the line; 4. Drilling and firing; 5. Slag out, anchoring, safety steel, spraying (including initial spraying and supplementary spraying) 6, advance anchoring (after the blue land section of the pipe shed) 7, measuring and pay-off; Then loop 4567

Taking the step excavation method as an example, the process of tunnel construction is: construction preparation - advanced geological prediction - measurement and pay-off - drilling hole on the step - charge blasting - ventilation and smoke exhaust - initial spraying concrete - blasting effect - ballast transportation - upper step initial support - monitoring and measurement - lower cycle excavation.

1. The three-step seven-step excavation method used in the excavation of the tunnel body mainly means that the tunnel is divided into 7 excavation faces, which are staggered with each other at the same time.

2. Hollow bolt grouting quick connector. Grouting operation, safe and fast.

3. Shotcrete: The initial support concrete of the construction tunnel, the initial shotcrete is dense and flat, and the quality is stable.

4. Steel arch processing: according to the total length of the tunnel steel arch, the material is in place at one time, and the whole is cold-formed and formed.

5. Processing and installation of link plates.

6. Processing and installation of secondary lining steel bars.

7. Tunnel waterproof treatment: the hot melt positioning device is used to fix the two lining waterproof plates.

8. Double-lined concrete: control the raw material.

Material quality, real-time adjustment of concrete fall, improve the vibration process, strengthen the repair and maintenance of the formwork vehicle, so that the surface of the concrete after demoulding is smooth and the gloss is consistent.

9. Lining concrete maintenance and water maintenance.

10. Installation of cable trench and drainage ditch.

Precautions: 1. Mingdong construction and cave door construction.

The excavation and support of the edge of the hole, the slope and the open hole should be excavated in layers from top to bottom.

Moreover, it is necessary to keep the outside of the cave, prevent and drain first, so that the surface water is smooth and the surface water is avoided from scouring the slope.

2. Excavation and support of shallow burial and crushing section of V-level surrounding rock at the entrance of the cave.

The overburden of the cave entrance section is thin, the geological conditions are poor, when the excavation depth reaches the arch line, the tunnel guide wall and the large pipe shed are applied first.

After the lining of the open hole is completed, the tail end of the long pipe shed is connected to the open hole, and the tail end of the pipe shed forms a fixed support.

1. Excavation of the mouth of the cave.

2. Arch construction.

3. Long pipe shed, or advanced small guide pipe support construction.

4. Excavation of the cave body.

5. Gang dao arch support Shi specialized worker.

6. Reinforcement mesh construction.

7. Jet concrete support.

8. Inverted arch construction.

9. Waterproof board, waterstop and drainage pipe installation.

10. Two lining steel bar binding.

11. a two-lining template.

12. Pouring the second lining concrete.

Taking the step excavation method as an example, the process of tunnel construction is: construction preparation - advanced geological prediction - measurement and pay-off - drilling hole on the step - charge blasting - ventilation and smoke exhaust - initial spraying concrete - blasting effect - ballast transportation - upper step initial support - monitoring and measurement - lower cycle excavation.

1.Concept of step excavation method. The step method is a construction method that excavates the upper half section first, excavates the lower half section at the same time after excavation to a certain length, and advances the upper and lower half sections at the same time; According to the length of the steps, there are three kinds of steps: long steps, short steps and ultra-short steps.

In recent years, due to the design of large-section tunnels, there are three-step temporary inverted arch method, or even multi-step method.

2.Selection of step excavation method. As for what kind of step method should be used in construction, it should be decided according to the following two conditions:

The time requirement for the formation of a closed section in the initial support, the worse the surrounding rock, the shorter the closing time requirement;

Requirements for the size of the construction site of mechanical equipment such as excavation, support, and ballast used in cross-section construction. In the weak surrounding rock, the former should be the main one, taking into account the latter, to ensure the safety of construction. When the surrounding rock conditions are better, it is mainly to consider how to better exert mechanical efficiency and ensure the economy of construction, so only the latter condition needs to be considered.

3.Advantages and disadvantages of the step excavation method: The step excavation method can have enough working space and a comparable construction speed.

However, there is interference in the upper and lower operations; Although the excavation of the steps increases the number of disturbances to the surrounding rock, the steps are conducive to the stability of the excavation face. Especially after the upper excavation support, the lower operation is safer, but attention should be paid to the influence of the lower operation on the stability of the upper part.

4.Precautions should be taken when excavating steps:

Solve the problem of mutual interference between the upper and lower sections of the operation. The micro-steps are basically combined into a single face for synchronous excavation; The long steps are basically stretched apart, and there is less interference; The interference of short steps is greater, so we should pay attention to the organization of operations. For tunnels with short lengths, the upper half section can be penetrated and the lower half section can be constructed.

When excavating the lower part, attention should be paid to the stability of the upper part. If the stability of the surrounding rock is good, it can be excavated in stages and sequences; If the stability of the surrounding rock is poor, the footage of the lower excavation cycle should be shortened. If the stability is worse, you can stagger left and right, or pull the middle groove first and then dig the edge.

The lower side wall must be sprayed immediately after excavation, and the initial support should be done according to the regulations.

The measurement work must be timely to observe the displacement of the vault, arch foot and side wall, and when the rate is found to increase, the inverted arch is immediately closed.

In the tunnel construction process, the initial support is a temporary payment, and the second lining is a permanent support.

1. Edge and slope construction before entering the hole (including drainage, electricity and other preparatory work);

2. Advance the construction of large pipe sheds.

3. Measurement, positioning, pay-off;

4. Drilling and firing;

5. Slag out, anchoring, safety steel, spraying (including initial spraying and supplementary spraying) 6, advance anchoring (after the pipe shed section).

7. Measuring and pay-off;

Then loop 4567

Hope it helps!

The above two floors said the initial support, two lining or something, are the drilling and blasting method of the underground excavation tunnel construction method content, the tunnel has a lot of construction methods, open excavation, dark excavation, shield tunneling, etc., the underground excavation tunnel is just one of them, I don't know what kind of construction method you want.

Measurement lofting drill hole charge blasting ventilation smoke exhaust, sprinkling water and dust out of the ballast to find the top arch, anchor, steel mesh operation shotcrete operation into the next cycle, the initial support is stabilized after the application of two linings: tunnel bottom excavation inverted arch waterproof plate, blind pipe,

1. Excavation construction plan:

In order to prevent the left and right holes from being excavated at the same time in the same section, and have a greater impact on the surrounding rock between the two tunnels, the method of excavating the right hole from the entrance and the left hole from the exit is adopted. The excavation is constructed by drilling and blasting method, and the excavation is carried out by smooth blasting technology. The import and export are mainly equipped with 1 rock drilling rig to drill holes, and 1 excavator to load ballast with 1 side unloading loader.

6 sets of 15t dump trucks were ballasted. The surrounding rock adopts the short step method, and the step length is 10-15m; The surrounding rock is constructed by the full-section method.

Second, the initial support construction plan:

The surrounding rock (S2) at the entrance of the cave is supported by advanced small conduit (grouting) and advanced mortar anchor (S3), reinforced mesh sprayed concrete and steel arch, and the surrounding rock is supported by composite anchor and sprayed steel fiber concrete. The construction sequence of support is: advance support (advance small conduit, advance mortar bolt) excavation initial spraying anchor, steel mesh, steel arch re-spraying to the design thickness.

The advance support is constructed before the excavation, and the initial support follows the excavation construction. The advanced mortar anchor is drilled by a drilling rig, the high-pressure grouting pump is used for grouting, and the sprayed concrete is applied by a wet spraying machine according to the wet spraying process. During the construction, the advanced geological forecasting and monitoring and measurement work should be conscientiously implemented to ensure that there is no collapse accident in the tunnel construction.

3. Tunnel lining construction plan:

The application time of the secondary lining is determined according to the monitoring and measurement data, and the tunnel lining in the surrounding rock section should be properly followed by the initial support, and the inverted arch and backfill should be carried out before the secondary lining. The secondary lining of similar surrounding rock can be appropriately lagged and applied after the initial support is basically stable. Before lining, the waterproof layer and plastic blind pipe should be constructed according to the design requirements. The waterproof layer and plastic blind pipe are constructed by self-made operation trolley, and the waterproof layer is laid without nails and fixed by thermal welding.

The lining of the tunnel adopts the full section construction of the through-type hydraulic lining trolley, and the tunnel entrance and exit ends are equipped with 1 trolley, and the trolley with a length of 9m is selected considering the factor that the tunnel is on the curve.

After the lining concrete of the emergency docking belt is completed in the whole tunnel, a movable, arc-shaped 3015 steel template is added in the trolley steel formwork, and the special comb mold is used to strengthen and adjust the size, and pedestrians, driving cross-holes and other reserved caverns adopt special bench construction. The concrete is made of S8 (C25) waterproof concrete, the concrete mixing truck is transported (more than 200m), the conveying pump pumps the concrete filling injection mold, and the mixing station is centralized mixing.

1. The three-step seven-step excavation method used in the excavation of the tunnel body is divided into seven excavation faces, and the excavation surface is staggered and opened at the same time.

2. Hollow bolt grouting quick connector, grouting operation.

3. Shotcrete, the initial support concrete of the construction tunnel, and the initial shotcrete is dense and flat.

4. The steel arch is processed, and the total length of the steel arch is cut in place at one time according to the total length of the tunnel collapse road, and the overall cold bending is formed.

5. Carry out the processing and installation of the link plate, and at the same time carry out the processing and installation of the lining steel bar.

6. The tunnel is waterproofed, and the hot-melt positioning device is used to fix the two lining waterproof plates.

7. Control the quality of raw materials, adjust the degree of concrete falling holes in real time, improve the vibration process, and strengthen the formwork vehicle.