What are the general requirements for waterproofing concrete for tunnels

The general requirements for waterproof concrete for tunnel works are as follows:

1. The impermeability grade of waterproof concrete in tunnel engineering has to be small S8.

2. When the lining is in the erosive groundwater environment, the erosion resistance system of concrete should not be less than. The erosion resistance coefficient of concrete is calculated as follows: ns=rws rwy, where ns is the erosion resistance coefficient of concrete; RWS is the flexural strength of concrete test blocks cured in erosion water for 6 months; RWY is the flexural strength of concrete test blocks cured in drinking water for 6 months.

3. When subjected to freeze-thaw action, pozzolana Portland cement and fly ash Portland cement should not be used.

4. The cement dosage of waterproof concrete for tunnel engineering shall not be less than 320kg m3, the cement strength grade shall not be lower than the grade, and the water-cement ratio shall not be greater than; When infiltrating the active fine powder, it shall not be less than 280kg m3.

5. The waterproof concrete structure should meet: (1) the crack width should not be greater than and not penetrate; (2) The protective layer of the main reinforcement on the frontal surface should not be less than 50mm; (3) The thickness of the lining should not be less than 30cm.

6. The impermeability level of the specimen should be higher than the design requirements.

7. When waterproof concrete is used, effective waterproof measures should be taken for various gaps in the lining to make the lining obtain the overall waterproof effect.

Answer] A [Answer Analysis] The test center is the construction content of the subway tunnel excavated by spraying anchors, which is a professional and technical test question. a is the correct optionAs the name suggests, the spray anchor excavation method is a construction technology of excavation and pouring at the same time, and its principle is:

Using the self-stabilizing ability of the soil layer in the excavation process for a short time, the non-slotted construction method of taking appropriate support measures to form a close-fitting thin-walled supporting structure on the surface of the surrounding rock or soil layer is mainly suitable for geology such as cohesive soil layer, sand layer and sand egg layer. Because the construction of the underground excavation method saves many procedures such as approval, demolition, and road excavation, it is widely used in urban underground engineering. Due to different geological conditions, the structure of the underground excavation construction tunnel is also changing

In the dry and waterless hard surrounding rock, the interval tunnel can be lined with a single layer, without waterproof isolation layer and secondary lining, but the construction technology and weathering resistance of shotcrete have higher requirements, and the surface of the lining concrete should be smooth, and a large number of cracks are not allowedWhen the waterproof requirements are not high and the surrounding rock has a certain self-stability ability, the interval tunnel can be lined with single-layer molded concrete, without initial support and waterproof isolation layer. Temporary supports made of wood, steel or spray anchors can be set up if necessary.

Unlike stressed units, in general, temporary supports are removed for the next use when concrete is poured. Single-layer molded concrete lining is also known as monolithic lining, in order to adapt to different surrounding rock conditions, monolithic lining can be made into equal cross-section straight wall type and equal cross-section or variable cross-section curved wall type, the former is suitable for hard surrounding rock, the latter is suitable for soft surrounding rock

Tunnel waterproofing engineering is a systematic engineering project involving many disciplines such as engineering, sealing, geology, etc., and the principle should be closely combined with engineering geology, hydrogeological conditions, engineering structure characteristics, engineering use and use requirements.

1. The design follows the comprehensive management principle of "combination of prevention, drainage, plugging and interception". Take a variety of measures to achieve the purpose of smooth drainage, reliable waterproofing, economic reasonableness, and no future troubles, so as to achieve the purpose of waterproofing;

2. The general principle of waterproof design should be based on prevention, multi-channel fortification, waterproof combination, and comprehensive treatment;

3. The tunnel lining structure can be made of self-waterproof concrete, which is regarded as a project and a permanent waterproof line to prevent seepage or leakage. Effective measures need to be taken during construction to prevent penetrating cracks in the structure;

4. The deformation joints must be reasonably set according to the characteristics of the project itself and the requirements of use, and the setting of the construction joints should be determined according to the specific research and determination of the construction conditions. In order to eliminate most of the shrinkage stress of concrete, the construction joints should be dense and not sparse, and the waterproofing of special parts such as deformation joints, construction joints and wall pipes should be strengthened;

5. The construction process of the tunnel waterproof board should ensure that the waterproof layer has the overall sealing of the connection;

6. If the shallow buried section of the tunnel entrance and exit is long, the overburden is mostly loose, and the surface has the characteristics of catchment topography, the water interception gutter can be set at the top of the tunnel, and the surface is partially grouted, and a certain range of the top plane of the tunnel is closed to prevent surface water infiltration.

The concrete structure is self-waterproofing.

The key to self-waterproofing of concrete structures is to ensure that the concrete is dense and that the concrete does not crack during construction. Ordinary waterproof concrete has shrinkage cracking, and compensating shrinkage concrete solves this problem well, it is mixed with expansion agent in cement or mixed with expansion cement.

Commonly used admixtures include anti-crack FS waterproofing agent, U-type expansion agent, etc. Practice has proved that the addition of admixtures can achieve ideal anti-cracking and anti-seepage effects.

The waterproof plugging of tunnels can be divided into front-mounted, middle-mounted and post-maintenance types in chronological order. The advantage of the front-loading type is that it prevents flooding. The creation construction was carried out in the absence of water.

Make the concrete body self-waterproof and other waterproof processes have a good construction environment. Achieve the best results. It can be done step by step to ensure the safety of construction and speed up the construction progress.

The mid-mounted type is carried out synchronously with tunneling, with water and water blockage. Eliminate flooding for road excavation. Speed up the construction schedule.

Ensure construction safety. The post-maintenance type is before the acceptance of the tunnel project. All tunnel leakage defects are completely repaired.

Achieve a high level of engineering. We have more than 30 years of experience in the construction of waterproof plugging structure reinforcement, and have done leakage plugging and reinforcement of dozens of tunnels of Daqin Railway. Provide free professional technical consultation on concrete waterproof leakage water repair, and introduce the performance of plugging materials.

Eliminate the trouble of repairing today, leaking tomorrow, repairing every year, and leaking every year.

Lay the waterproof board. Buried drains. Grouting waterproofing. See what situation and what method to use.

Tunnel moisture needs to be waterproofed, choose waterproof materials to be cautious, let's take a look at the tunnel waterproof materials, tunnel waterproofing practices.

What are the waterproofing materials for tunnels.

1. FYT-1 improved waterproof Huizhihu coating (HC-201) is a kind of polymer composite material, which is a national key science and technology promotion project, and has reached the leading level of similar products by experts organized by national authoritative departments. The product has been tested by the Highway Engineering Testing Center of the Ministry of Communications, and all technical indicators meet the requirements of JT T575-2005 standard.

2. FYT-2 polymer bridge deck waterproof coating (H-C-202) can be used alone, or it can be used in combination with FYT-1 improved waterproof coating for bridge deck waterproofing, which can prevent steel corrosion caused by water leakage of concrete bridge deck and improve the service life of the bridge body.

3. Self-adhesive polymer modified asphalt waterproofing membrane.

The PY self-adhesive polymer modified asphalt polyester tire waterproofing membrane is a high-speed tunnel waterproofing material based on filament polyester felt, and a waterproof material for railway tunnels with tackifying polymer modified asphalt as the dipping material, and the upper surface is covered with polyethylene film, fine sand, leaf rock, aluminum foil or isolation film as the waterproof material for the isolation layer of the construction tunnel.

4. Fast response sticky strength cross Mo self-adhesive waterproof membrane.

Scope of application: It is mainly used for non-exposed engineering ignition, basement waterproof engineering, as well as open-cut subway, tunnel, canal and other engineering waterproofing, especially suitable for projects that are not allowed to use open flames.

What are the waterproofing practices for tunnels.

1) Watertight waterproofing, starting from the surrounding rock, structure and additional waterproof layer, reflecting the drainage based on prevention, also known as all-inclusive waterproofing;

2) Drain type or drainage self-draining type, starting from drainage and drainage, reflecting the drainage-based, also known as semi-package waterproof;

3) Control type anti-drainage combined with anti-drainage.

The main types of tunnel drainage prevention and drainage structure are different lining types: composite lining drainage structure, single-layer lining drainage structure, partition wall drainage structure in arch tunnel, and open hole drainage prevention structure.

Precautions for tunnel waterproofing construction.

1) Before the waterproof board is laid, the steel bar head and anchor head at the surface of the shotcrete are cut off first, and then smoothed with a hand-held grinder, and the uneven parts should be repaired and sprayed to make the concrete surface smooth, and there is local water seepage, which should be treated.

2) The waterproof board is laid in the circumferential direction, and the welding process and the fixing process should be closely coordinated, generally welded first, and then fixed.

3) The lap width of the waterproof board laying is 10 cm, the welding width is not less than 2 cm, the missing welding, false welding should be repaired, if there is scorching, welding penetration, the same waterproof board welding paste should be covered or handled according to the instructions of the supervising engineer.

4) The fixed waterproof board is welded by glue and heat, and the waterproof layer between the rubber pad and the rubber pad shall not be tightened, and the board surface and shotcrete should be closely attached.

1. Waterproofing membrane.

The waterproofing membrane is made of organic polymer liquid material and inorganic powder, which can form a high-strength and tough waterproof coating film after coating. Often used in building walls, tunnels, highways, landfills and other areas, soft texture, can be curled flexible building materials products, effectively resist underground seepage or external rainwater defense effect. It is a popular tunnel waterproofing material in the market.

2. Rigid waterproof material.

The raw materials of rigid waterproof materials are mainly cement and sand, and a small amount of admixtures and polymers are mixed into the production to change the pore characteristics to a certain extent, inhibit or reduce the porosity, and increase the contact surface between the interfaces. Reduce the gap between particles and formulate concrete waterproof materials with good permeability resistance.

3. Flexible waterproof material.

The flexible tunnel waterproof material is mainly made of rigid tunnel waterproof materials such as waterproof mortar and waterproof concrete, which has good stretchability and is suitable for use in areas with large changes in the shape of the mechanism, but the flexible waterproof material has higher requirements for the construction technology level of the team, so it is used less.

Second, which is the best waterproof material for the tunnel?

Waterproofing membrane is a more commonly selected waterproof material, generally used for the waterproof layer of the first layer of the tunnel, and the rigid waterproof material has good impermeability, so it is often used as the surface layer of tunnel waterproofing, and is very strong. The flexible waterproof material is suitable for waterproofing work with large changes in construction shape, and has good stretchability.

Hello, in the construction of railways, highways and other tunnels, VA waterproof board is used as the main waterproof material, and concave-convex waterproof board is mainly used as hydrophobic and drainage, so in the construction of water-rich tunnels, concave-convex waterproof board is mainly used. However, tunnels with less water seepage in the surrounding rock and initial support are rarely used.

Waterproofing membrane (PVC waterproofing membrane) PVC waterproofing membrane mainly uses polyvinyl chloride as the main raw material, supplemented by heat stabilizers, reinforcing agents, antioxidants, etc., through high-speed mixing, and then extruded by twin-screw extruder and mold, three-roller machine, and cooled to obtain medium and high-grade waterproof membrane. PVC waterproofing membrane has high tensile strength 、..

Waterproofing membrane EVA waterproofing membrane is made of high-quality ethylene-vinyl acetate copolymer as the main raw material, and antibacterial agents are specially added to the material to prevent microbial erosion. EVA waterproofing membrane has high tear strength, good puncture resistance, waterproof impermeability, and hydrolysis resistance, and is widely used in tunnels, subways, highways, etc

At this stage, how do construction enterprises lay tunnel waterproof panels, and what are the construction requirements? The following is the relevant content of professional construction terminology of Zhongda Consulting to sort out the requirements for laying tunnel waterproof panels, and the basic situation is as follows:

1. Carry out accurate lofting before laying, and determine the size of one ring of the waterproof board after popping up the standard line for trial laying, so as to minimize the joints.

2. The waterproof board should be laid without nails, and it is advisable to lay in the order from bottom to top, and the tightness should be moderate and leave a margin (the ratio of the actual paving length to the arc length is 10:8), and the inspection should ensure that the entire area of the waterproof board can reach the surrounding rock.

3. Use a nail with a thermoplastic round washer to fix the buffer layer on the base layer smoothly and straightly, the lap width of the buffer layer is 50mm, and the hot air welding torch can be used for spot welding, each waterproof board is arranged with an appropriate number of washers, each row of washers is about 40cm away from the edge of the waterproof board, and the gasket spacing: side wall 80cm, 2 3 washers m2, top 40cm, 3 4 washers m2.

4. The lap width of the two waterproof plates should not be less than 100mm.

5. When laying in the ring direction, the wall should be arched first, and the lower waterproof plate should press the upper waterproof board.

6. The lap joints between the waterproof plates should be hot-melt welded by automatic crawling heat sealing machine with double welding, temperature regulation and speed regulation hot wedge functions, and hand-held welding guns should be used for detail treatment or repair, and the effective welding width of a single weld should not be less than 10mm, and the welding should be tight, and no coke welding should be carried out.

7. The longitudinal lap joint and the circumferential lap joint of the waterproof board, in addition to the normal construction, should be covered with a layer of waterproof plate of the same material and welded with heat welding.

8. The lap form of the plastic waterproof board with more than three layers must be a "T" type flame joint.

9. The edge part of the membrane laid in Qingying virtual section should leave at least 60cm lap allowance and effectively protect the edge part of the reserved part.

10. When binding or welding steel bars, measures should be taken to avoid damage to the coil.

11. When the concrete is vibrating, the vibrating rod shall not touch the waterproof plate to prevent the waterproof plate from being damaged.