CN115093142A - Railway tunnel lining concrete anti-cracking functional material and concrete and application thereof - Google Patents

Abstract

The invention discloses a railway tunnel lining concrete anti-cracking functional material, which includes a self-curing material and a tie material; wherein the self-curing material is a lightweight porous material, and the tie material is a steel-organic fiber composite material. The technical scheme of the invention covers the functional material composition, key parameters of mixing ratio and key construction process control of high-speed railway tunnel lining concrete shrinkage cracking and block drop functional materials and applications, and the material can effectively reduce the shrinkage of tunnel lining concrete under the aerodynamic effect of high-speed trains. The risk of cracking and falling blocks ensures the safe and stable operation of high-speed trains.

Description

A kind of railway tunnel lining concrete anti-cracking functional material and its concrete and application

technical field

The invention belongs to the technical field of tunnels, and in particular relates to a railway tunnel lining concrete anti-cracking functional material and its concrete and application.

Background technique

With the continuous advancement of infrastructure construction, the focus of railway construction has gradually shifted to the western region. The western region is dominated by plateaus and mountains, with numerous mountains and complex terrain. Tunnel engineering has become an important part of the construction of the Western Railway. The composite lining structure is generally used in railway tunnels, and the secondary lining concrete is an important bearing structure for railway tunnels and an important guarantee for long-term durability of the tunnel. Therefore, ensuring the safe and durable service of the secondary lining concrete of railway tunnels is an important guarantee for realizing the century-long durability of railway tunnel projects and the normal operation of high-speed railways.

However, the practice of existing and under-construction tunnel engineering shows that the secondary lining concrete of the tunnel has some problems such as cracking and falling blocks caused by shrinkage and deformation, and has become a key problem that affects the durability of railway tunnel engineering and threatens the safety of trains. More importantly, in addition to the conventional shrinkage stress, the secondary lining concrete of the railway tunnel will also be affected by the aerodynamic effect of the train. In the high-speed rail operating environment, the aerodynamic effect (ie, transient high-speed airflow) generated by the train will aggravate the loss of water in the surface and interior of the tunnel lining concrete, thereby accelerating the development of shrinkage strain and eventually causing shrinkage cracking of the concrete. This also makes the deterioration phenomena such as cracking and falling blocks of the railway tunnel lining concrete more obvious in the actual project. Therefore, according to the service characteristics of high-speed railway tunnel secondary lining concrete, the corresponding shrinkage cracking and block drop prevention methods are proposed, which is of great significance to improve the durability of railway engineering tunnel lining concrete and ensure the safe and stable operation of high-speed trains.

The aerodynamic effect of trains has a wide range of meanings, but the effect of transient high-speed airflow generated by train operation has a significant impact on the durability of tunnel lining concrete. The reason for the above phenomenon is that the tunnel is a semi-enclosed space. When the high-speed train passes at a speed of 250km/h or higher, due to the viscosity of the air and the friction effect of the airflow on the tunnel wall and the train surface, the concrete surface of the tunnel lining will be damaged. A transient airflow (shown in Figure 1) will be created. The research results show that when the train passes through the tunnel at a speed of 250km/h, the transient airflow velocity on the inner wall can reach 30m/s, and with the increase of the train's running speed, the above effects gradually increase. The acceleration effect of transient high-speed airflow on the deterioration of tunnel lining concrete is mainly manifested in its influence on the moisture transfer rate and humidity field inside the concrete. The change of the humidity field inside the concrete will directly affect the development of shrinkage strain, which will lead to shrinkage cracking.

In order to reduce the risk of shrinkage cracking and falling blocks of tunnel lining concrete, some methods have been proposed in existing research, for example: Chinese invention patent CN201911408297.4 discloses a microbial self-healing method for tunnel lining concrete cracks. Repair cracked tunnel lining concrete; experimental research results show that this method has a good self-healing effect on concrete cracks, especially for concrete with a cracking width of less than 0.5mm after 90 days of age. 5 A kind of anti-cracking steel mesh for tunnel lining is disclosed. The steel mesh is composed of circumferential threaded steel bars and ordinary steel bars, and is fixed on the longitudinal steel bars of the tunnel lining, which can significantly reduce the risk of cracking and falling of blocks in the tunnel lining concrete; CN202120076526.3 A new type of lining structure for preventing high-speed rail tunnels from falling off blocks is disclosed. The structure reduces the risk of tunnel lining concrete cracking and falling blocks by introducing two-limb steel frames and single-layer steel mesh sheets. CN202021580256.1 discloses the lining of tunnel vaults Concrete anti-falling reinforcement structure, which reduces the risk of tunnel lining concrete falling off on train operation by setting fastening bolts and protective nets on the tunnel lining surface. It can be seen from the above analysis that most of the existing patents reduce the risk of concrete cracking from the perspective of installing protective devices or reinforcement on the surface of the tunnel lining concrete, and further propose a repair method after cracking. However, the installation of protective devices on the surface of the lining concrete needs to increase the construction difficulty, and the protective devices themselves are also easy to fall off under the aerodynamic effect of the train. Simply adding reinforcement in the lining concrete can reduce the risk of cracking and falling blocks to a certain extent, but the configuration of steel bars will significantly increase the construction cost of the tunnel structure, resulting in a lot of waste of steel, and the configuration of steel bars cannot fundamentally solve the problem of concrete cracking. More importantly, compared with traditional structural concrete, tunnel lining concrete has a more special service environment, that is, the aerodynamic effect of trains.

Therefore, it is an urgent problem for those skilled in the art to provide a functional material for railway tunnel lining concrete that can solve shrinkage cracking and block drop.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a functional material and application of shrinkage cracking and block drop of high-speed railway tunnel lining concrete covering key functional material design, key parameters of mixing ratio and construction key process control, which can effectively reduce the air pollution of high-speed trains. Under the dynamic effect, the tunnel lining concrete shrinks, cracks and blocks the risk of falling blocks, ensuring the safe and stable operation of high-speed trains.

In order to achieve the above object, the present invention adopts the following technical solutions:

A railway tunnel lining concrete anti-cracking functional material, including self-curing material and tie material;

Wherein, the self-curing material is a lightweight porous material, and the tie material is a steel-organic fiber composite material.

Preferably, the particle size of the self-curing material is 5-10 mm, and the water absorption rate of the self-curing material is ≥20%.

Porous ceramsite or other commonly used porous materials are used as lightweight porous materials. The pre-absorbed water in the lightweight aggregates can be released during the subsequent drying process of the concrete to supplement the water in the capillary pores of the concrete, thereby reducing the shrinkage stress of the capillary pores and reducing shrinkage cracking. Especially under the aerodynamic effect of the train, the water loss of the tunnel lining concrete is accelerated, and it is particularly important to use the pre-absorbent lightweight aggregate self-maintenance technology.

The size of the self-curing porous material will affect the self-curing effect and the mechanical properties of concrete. If the material size is too small, it will lead to insufficient water storage and poor curing effect;

The water absorption rate of the self-curing material is an important factor affecting the self-curing effect. After a large number of experiments, the present invention found that when the water absorption rate of the self-curing material is not less than 20%, the curing effect can meet the self-curing requirements of high-speed railway tunnel lining concrete.

Preferably, the self-curing material needs to undergo pre-water absorption treatment.

Preferably, the volume ratio of steel fibers to organic fibers in the steel-organic fiber composite material is 1.5-2.0.

Preferably, the ends of the steel fibers are provided with hooks, and the length is 30-40mm;

The organic fibers are polypropylene fibers with surface indentation treatment, and the length is 8-12 mm.

Adding fibers to the tunnel lining concrete will effectively control the crack width, and once the concrete cracks, the fibers will effectively tie the concrete blocks to reduce the risk of falling blocks; it can be seen that the role of fibers in the tunnel lining concrete is divided into crack width control And pull knot to prevent the block from two aspects. Aiming at this feature, the present invention selects a steel-organic fiber composite system, the steel fibers mainly tie up large cracks, and pull the concrete to drop blocks, and the main function of the organic fibers is to control the width of small concrete cracks.

Based on the principle of microscopic mechanics, fiber belt end hooks or proper extension of fiber anchoring length will effectively increase the tie effect of fibers, but too long fiber length will affect the workability of concrete. The length of steel fiber selected in the present invention should be longer than that in tunnel lining concrete Maximum aggregate particle size (25mm), but less than 40mm.

The surface scoring treatment of organic fibers will significantly increase the gripping force between them and cement-based materials, thereby increasing the crack control ability; since the role of organic fibers is mainly to control tiny cracks in cement-based materials, its length is 8- Best between 12mm.

In the steel-organic fiber composite system, the main role of steel fiber is to control the width of structural cracks and to tie larger concrete, and the main role of organic fiber is to control the width of smaller cracks. In view of the above effects, the present invention shows through a large number of experiments that when the volume ratio of steel fibers to organic fibers is between 1.5 and 2.0, the crack control of tunnel lining concrete under the aerodynamic effect of trains is the most effective.

A railway tunnel lining concrete, comprising the above-mentioned functional materials.

Preferably, the concrete slump is 230-260mm, and the air content is 6.0-8.0%.

Preferably, the dosage of the self-curing material is 0.08-0.12 in mass ratio of the introduced self-curing water to the cementitious material, and the volume dosage of the tie material is 0.5-0.7%.

In the large-scale construction process of tunnel lining, concrete workability (ie slump) is the key to affecting the compactness of tunnel lining concrete. The research of the present invention shows that when the workability of tunnel lining concrete is between 230-260mm, the lining concrete will not be under construction. The compaction can be achieved under the action of simple vibrating on site, and there is no concrete bleeding, etc.;

The air content of concrete is the key to affecting its fluidity. If the air content is too low, the fluidity of the concrete will be poor, and if the air content is too high, the strength of the concrete will be low; the present invention has been verified by a large number of tests, and the air content of the lining concrete can be taken into account when the air content is between 6.0-8.0%. Concrete flow and strength.

The amount of self-curing water introduced by the use of pre-absorbent lightweight aggregate is the key to affecting the self-curing effect. If the self-curing water is too small, the self-curing effect of the concrete will be poor and cannot meet the requirements of shrinkage control; if the self-curing water is too much, the mechanical properties of the concrete will be significantly reduced. . The invention proposes the concept of self-curing water-to-binder ratio, that is, the self-curing effect is best when the ratio of self-curing water introduced through pre-absorbent light aggregate to cementitious material is between 0.08 and 0.12.

The key material for knotting is the mixture of steel fiber and organic fiber, and its content is the key to affecting crack control and knotting effect. If the fiber content is too high, the workability of concrete will be affected, and if the fiber content is too low, the tie effect will be poor. The present invention has been verified by tests, and when the volume content of the composite fiber is between 0.5-0.7%, it can meet the requirements of tunnel lining concrete tension and workability.

As described above in the application of the concrete in the lining structure of a high-speed railway tunnel, the lining structure further includes a water-permeable and air-permeable layer on one side of the concrete.

The water-permeable and breathable material is used, and the material is attached to the inner surface of the formwork before the concrete is poured. After the concrete is poured, the water and air bubbles on the surface of the lining concrete are discharged through the material, so as to optimize the concrete hole structure of a certain thickness near the inner surface of the tunnel lining concrete and improve the The inner surface of the lining concrete is dense to form a protective "shield shell".

Preferably, the drainage capacity of the water-permeable and breathable layer is greater than or equal to 4.0 L/m ² , and the air permeability is greater than or equal to 4.0 m ³ /m ² s.

Preferably, the water-permeable and breathable layer is composed of a filter layer, a water-permeable and breathable material layer and an adhesive layer;

Among them, the filter layer is a porous material, which can only pass the excess water and gas on the concrete surface, but the cement particles cannot pass through; the water-permeable and breathable material layer adopts polypropylene fiber to achieve the required drainage and breathability through three-dimensional space design; the role of the adhesive layer is to Paste the above water-permeable and breathable material to the inner side of the steel formwork.

After the concrete is poured, there are free water and air bubbles on the surface. The existence of the two is the essential reason for the poor compactness near the concrete surface. This is also the essential reason why the tunnel lining concrete surface is more prone to cracking under the aerodynamic effect of high-speed trains. Based on this, the present invention proposes to arrange a water-permeable and breathable material on the surface of the tunnel lining concrete, which is attached to the surface of the steel formwork before the concrete is poured. compactness. A shield shell is formed on the surface of the tunnel lining concrete to resist the aerodynamic effects of the train in the environment.

Based on the above analysis, the drainage capacity of the permeable and breathable material will directly affect its effect. The unilateral mixing water for railway tunnel lining concrete is about 200 kg, the scope of action of the permeable and breathable material is about 2 cm deep on the concrete surface, and the total amount of free water is about 4.0 L. Therefore, the drainage capacity of the tunnel lining concrete permeable and breathable material is ≥4.0 L/m ² .

The air permeability of the water-permeable and breathable material is the key to its exhaust effect. According to the test of the present invention, when the air-permeability of the water-permeable and air-permeable material is ≥4.0 m ³ /m ² s, it can meet the exhaust requirements of the high-speed rail tunnel lining concrete surface.

It can be seen from the above-mentioned technical solutions that, compared with the prior art, the beneficial effects of the present invention are as follows: Starting with the preparation of key parameters and the regulation method of the pore structure on the inner surface of the tunnel lining concrete, a complete technical system for the prevention of shrinkage cracking and falling blocks of the railway tunnel lining concrete is proposed. The tunnel lining concrete can be prevented from cracking under the aerodynamic effect of the high-speed train. More importantly, even if the tunnel lining concrete cracks under the load of the tunnel surrounding rock, the crack width can be effectively controlled to ensure that no falling blocks occur. car phenomenon. This technology can be used in the secondary lining concrete construction process of railway and highway tunnels, which can effectively improve the crack resistance of tunnel lining concrete, reduce the risk of falling blocks in the tunnel lining, and ensure the safe operation of high-speed railway trains. This technology is widely used and worthy of promotion.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are used in the description of the embodiments or the prior art, and the drawings in this description are only the present invention. example.

Fig. 1 is the aerodynamic effect of the high-speed train of the present invention and its influence on the tunnel lining concrete; wherein, (a) is the train entering the tunnel, and (b) is the train going out of the tunnel;

Fig. 2 is the high-speed rail tunnel lining structure diagram of the present invention; wherein, 1-concrete layer, 2-water-permeable and breathable layer, 3-steel formwork;

Figure 3 is a comparison diagram before and after the adjustment technology of the concrete surface pore structure of the present invention; wherein, (a) is the adjusted surface pore structure, and (b) is the adjusted surface pore structure;

FIG. 4 is a diagram of a test method for shrinkage deformation of tunnel lining concrete according to the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in FIG. 2, it is the application of a functional material for concrete in the lining structure of a railway tunnel according to the present invention, which includes a concrete layer 1, a water-permeable and breathable layer 2 and a steel formwork 3. The concrete layer 1 includes the functional material, and the water-permeable layer is The breathable layer 2 includes a water-permeable and breathable material;

The water-permeable and breathable layer 2 is composed of a filter layer, a water-permeable and breathable material layer and an adhesive layer;

Among them, the filter layer is a porous material with a pore diameter between 25-30μm. This material can only pass the excess water and gas on the concrete surface, but the cement particles cannot pass through; the water-permeable and breathable material layer is made of polypropylene fiber. Drainage and air permeability, the thickness is about 1.5mm; the function of the adhesive layer is to paste the above water-permeable and air-permeable material to the inner side of the steel formwork.

Example 1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the steel-organic fiber composite material, the steel fiber with a hook at the end is selected, the length is 35mm, the surface of the polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 2-1

In a railway tunnel lining structure, the parameters of the functional material used for the tunnel lining concrete are: the self-curing material selects porous ceramsite, the average particle size is 3mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 2-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 12mm, the water absorption rate is 23%, and the concrete is immersed in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 3-1

In a railway tunnel lining structure, the functional material parameters for tunnel lining concrete are: self-curing material selects porous ceramsite, with an average particle size of 7 mm and a water absorption rate of 15%, soaking in water for 24 hours for pre-water absorption treatment before concrete is formed; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 4-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 20mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 4-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 45mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 5-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 5mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 5-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 15mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 6-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.0;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 6-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 2.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 7-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 200mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 7-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 280mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 8-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 4%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 8-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 10%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 9-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.04, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 9-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.15, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 10-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.3%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 10-2

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.9%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 11-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 2.0 L/m ² and a breathable capacity of 4.0 m ³ /m ² s.

Example 12-1

In a railway tunnel lining structure, the parameters of the functional material for tunnel lining concrete are: self-curing material selects porous ceramsite, the average particle size is 7mm, the water absorption rate is 23%, and the concrete is soaked in water for 24 hours before pre-absorption treatment; In the knot material, the steel fiber with hook at the end is selected, the length is 35mm, the surface of polypropylene fiber is indented, the length is 10mm, and the volume ratio of steel fiber to organic fiber is 1.5;

The key parameters of tunnel lining concrete mix ratio include: slump of 240mm, air content of 7%, self-curing water-binder ratio of 0.1, and tie material volume content of 0.6%;

The water-permeable and breathable material has a drainage capacity of 4.0 L/m ² and a breathable capacity of 2.0 m ³ /m ² s.

Wherein, the reference mix ratio of the raw materials used in the concrete of all the above-mentioned embodiments except the functional material is as follows:

Table 1 Benchmark mix ratio of concrete

In addition, the mechanical properties and shrinkage properties of the tunnel lining concrete of the above-mentioned embodiments are tested, wherein the mechanical properties mainly include 28d concrete compressive strength and tensile strength tests; the shrinkage properties are mainly the tunnel lining concrete 28d drying shrinkage under the aerodynamic effect of the train , the test process is shown in Figure 4. Two deformation sensors are set at both ends of the concrete test block to test the shrinkage deformation of the concrete in real time. A PTFE backing plate is laid on the block under the concrete test block to reduce the size of the concrete. For the friction force during the deformation process, an air induction channel is set above the concrete specimen, and a variable frequency fan is set on one side, which can simulate the high-speed airflow on the concrete surface when the train passes. During the test, the wind speed on the concrete surface was controlled by the variable frequency fan to be 30m/s, which was the same as the wind speed on the surface of the lining concrete under the operating conditions of the train.

Table 2 Mechanical properties and shrinkage properties of tunnel lining concrete in each example.

From the above-mentioned table 2 parameter design and test results statistics, it can be seen from Example 1 that when constructed according to the key technology proposed in the present invention, the 28d compressive strength of the obtained tunnel lining concrete can reach 51.5MPa, and the tensile strength can reach 10.5MPa , under the influence of the aerodynamic effect of the train, the 28d drying shrinkage rate is only 178με. It can achieve the characteristics of high compressive strength, high tensile strength and small shrinkage deformation, and meet the requirements of tunnel lining concrete shrinkage deformation free from cracking and block drop;

Comparing Examples 1 and 2-1/2-2, it can be seen that with the unreasonable reduction of the average particle size of the self-curing material (3mm), the drying shrinkage of the tunnel lining concrete at 28d increases significantly, up to 385με; The self-curing material with too small diameter has poor curing effect, but when the average particle size of the self-curing material increases unreasonably (12mm), the 28d compressive strength and tensile strength of tunnel lining concrete decrease significantly (42.8MPa and 7.9MPa). ), which indicates that the self-curing porous material can be regarded as a defect inside the concrete, and when the particle size is too large, the defect is too large, which in turn leads to a decrease in the strength of the concrete;

Comparing Examples 1 and 3-1, it can be seen that when the water absorption rate of the self-curing material is unreasonably reduced (15%), the compressive strength and tensile strength of tunnel lining concrete are significantly reduced, which are 40.1 MPa and 6.8 MPa, respectively. The reason is that, The invention controls a constant internal curing water-binder ratio, and when the water absorption rate decreases, the self-curing materials incorporated in it are bound to increase, thereby causing the concrete strength to decrease;

Comparing Examples 1 and 4-1/4-2, it can be seen that when the length of the steel fiber is unreasonably shortened (20mm), the tensile strength of the tunnel lining concrete is significantly reduced (5.6MPa), which means that the length of the steel fiber is too short to be tied. The compressive strength and tensile strength of concrete decrease at the same time (43.6MPa and 6.3MPa) when the length of steel fiber increases unreasonably (45mm), which indicates that the fiber length If it is too long, it will seriously affect the workability of concrete, resulting in poor concrete compactness and decreased mechanical properties;

Comparing Examples 1 and 5-1/5-2, it can be seen that when the length of the organic fibers is unreasonably shortened (5mm), the tensile strength of the tunnel lining concrete decreases (8.3MPa), which means that the fiber length is too short and cannot be tied together. Cement-based material on both sides of the crack, which in turn leads to a decrease in the tensile strength of concrete; when the length of organic fibers is unreasonably increased (15mm), the compressive strength and tensile strength of concrete decrease at the same time. The reason is similar to that of steel fibers, and the fiber length is too long. It will directly affect the workability of concrete and cause its compressive and tensile strength to decrease;

Comparing Examples 1 and 6-1/6-2, it can be seen that when the volume ratio of steel fibers to organic fibers increases or decreases unreasonably (1.0/2.5), the tensile strength of tunnel lining concrete decreases; Fiber and organic fiber play different roles in concrete, and the ratio of the two directly determines the use effect of the mixed fiber system. Too high or too low ratio may lead to deviations in the control effect of large and small cracks in concrete;

Comparing Examples 1 and 7-1/7-2, it can be seen that when the slump of concrete increases or decreases unreasonably (200mm/280mm), the compressive strength and tensile strength of concrete decrease, and the drying shrinkage rate decreases. increase. The reason is that if the concrete workability is too small, the compactness of the poured concrete will be poor, which will affect the above performance; while when the concrete workability is too large, there will be the risk of segregation or bleeding, which will also lead to poor concrete pouring effect, which will affect the above performance. performance;

Comparing Examples 1 and 8-1/8-2, it can be seen that when the air content of the concrete is unreasonably reduced or increased (4%/10%), the compressive strength and tensile strength of the concrete are reduced, and the drying shrinkage rate is The reason is that when the air content of the concrete decreases, the ball effect produced by the gas in the concrete is weakened, which leads to the deterioration of the fluidity of the concrete, which in turn affects the compactness of the poured concrete; leads to a decrease in the mechanical properties and an increase in the shrinkage rate; and When the air content increases unreasonably, there will be too many defects in the concrete, which will lead to the decline of its mechanical properties and the increase of drying shrinkage;

Comparing Examples 1 and 9-1/9-2, it can be seen that when the self-curing water-to-binder ratio is unreasonably reduced (0.04), the drying shrinkage of concrete increases significantly (572με), which shows that unreasonably reducing self-curing water will significantly When the self-curing water-binder ratio increases unreasonably (0.15), the mechanical properties of concrete decrease significantly; the reason is that the increase of the self-curing water-binder ratio will inevitably lead to an increase in the introduction of porous media, which in turn affects the concrete. mechanical properties;

Comparing Examples 1 and 10-1/10-2, it can be seen that when the volume content of the tie material is unreasonably reduced (0.3%), the tensile strength of concrete is significantly reduced (3.2MPa), and the drying shrinkage rate is significantly increased (368με) ; The reason is that the decrease of fiber content will directly lead to the decrease of the tie effect, which will lead to the decrease of ultimate tensile strength; at the same time, it will affect the limiting effect of fibers on the volume deformation of cement-based materials, which will lead to the increase of drying shrinkage; When the volume content of the junction material is unreasonably increased (0.9%), the compressive and tensile strength of concrete also decreases, and the drying shrinkage rate also increases. This may be related to the poor workability of concrete caused by excessive fiber content;

Comparing Examples 1 and 11-1, it can be seen that when the water permeability of the water-permeable and breathable material is unreasonably reduced (2.0 L/m ² ), the drying shrinkage of concrete increases significantly (479 με); The key to its surface compactness is that when the surface water cannot be discharged in time, it will directly lead to the decrease of the compactness of the concrete surface, which in turn affects its shrinkage and deformation results under the aerodynamic effect of the train;

Comparing Examples 1 and 12-1, it can be seen that when the air permeability of the water-permeable and breathable material is unreasonably reduced (2.0 m ³ /m ² s), the drying shrinkage of concrete increases significantly (437 με); It is the key to affecting the water loss properties of concrete under the aerodynamic effect of the train. When the gas cannot be discharged in time, the compactness of the concrete surface will decrease, which will lead to its later drying shrinkage becoming larger.

Figure 3 is a comparison diagram of the concrete surface pore structure proposed by the present invention and the surface pore structure of the prior art, wherein the white is the pores, and the black is the cement slurry or aggregate; : The number of pores on the concrete surface constructed by conventional technology is more, and the pores of larger size are more; and after using the method for regulating the structure of concrete surface pores of the present invention, the overall number of pores on the concrete surface is significantly reduced, and the pores of large size basically disappear.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. a railway tunnel lining concrete anti-cracking functional material, is characterized in that, comprises self-curing material and tie material; Wherein, the self-curing material is a lightweight porous material, and the tie material is a steel-organic fiber composite material. 2 . The anti-cracking functional material for railway tunnel lining concrete according to claim 1 , wherein the particle size of the self-curing material is 5-10 mm, and the water absorption rate of the self-curing material is greater than or equal to 20%. 3 . 3 . The anti-cracking functional material of railway tunnel lining concrete according to claim 1 , wherein the self-curing material needs to be pre-absorbed. 4 . 4 . The anti-cracking functional material for railway tunnel lining concrete according to claim 1 , wherein the volume ratio of steel fibers and organic fibers in the steel-organic fiber composite material is 1.5-2.0. 5 . 5. The anti-cracking functional material for railway tunnel lining concrete according to claim 4, wherein the steel fiber has a hook at the end, and the length is 30-40mm; The organic fibers are polypropylene fibers with surface indentation treatment, and the length is 8-12 mm. 6 . The anti-cracking functional material for railway tunnel lining concrete according to claim 1 , wherein the content of the self-curing material in the concrete is that the mass ratio of the self-curing water introduced and the cementitious material is 0.08- 0.12, the volume dosage of the tie material in the concrete is 0.5-0.7%. 7. A railway tunnel lining concrete, characterized in that it comprises the functional material of claims 1-6. 8 . The railway tunnel lining concrete according to claim 7 , wherein the slump of the concrete is 230-260 mm, and the air content is 6.0-8.0%. 9 . 9 . The application of concrete in the lining structure of a high-speed railway tunnel according to claim 7 , wherein the lining structure further comprises a water-permeable and air-permeable layer on one side of the concrete. 10 . 10 . The application according to claim 9 , wherein the drainage capacity of the water-permeable and air-permeable layer is ≥4.0 L/m ² , and the air permeability is ≥ 4.0 m ³ /m ² s. 11 .

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