A method for microwave-assisted solidification of primary support concrete in tunnels and freeze protection in cold regions

Abstract

The present invention relates to the technical field of geotechnical engineering, and specifically to a method for microwave-assisted setting of primary support concrete in tunnels and anti-freezing in cold regions. The main implementation steps of this method include: S1: Excavating the tunnel face of a highway tunnel; S2: Conducting initial spraying of concrete and microwave irradiation; S3: Stopping the initial spraying of concrete and microwave irradiation after reaching the standard; S4: Driving tunnel bolts, installing steel mesh and steel supports; S5: Conducting secondary spraying of concrete and microwave irradiation; S6: Moving to the completion point of excavation of the next tunnel face after reaching the standard. The present invention applies the principle of microwave irradiation to the shotcrete technology, which can accelerate the rapid setting of concrete, solve the problem that the rate of accelerating the setting of concrete in the prior art is slow, and the limitation of uneven heating exists in the traditional heating method. It can improve the early strength of concrete, improve the overall stress condition of the tunnel, enhance the overall stability of the tunnel, shorten the construction period, and save the project cost; at the same time, it also increases the initial temperature of the concrete, which can be used for anti-freezing of concrete pouring in cold regions.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering, and particularly relates to a method for microwave-assisted setting of primary support concrete in tunnels and anti-freezing in cold regions. Background Art

[0002] Shotcrete is widely used in fields such as tunnel construction, underground engineering, geotechnical engineering, and municipal engineering. The working principle of shotcrete is that under the power of compressed air or a high-pressure pump, the concrete mixture is sprayed onto the support surface through a spraying device and coagulates and hardens within a few minutes, playing a role in sealing and supporting. However, even when using a quick-setting agent, shotcrete still has a certain initial setting time, which brings a lot of trouble to tunnel construction. By the principle of microwave irradiation, the setting of concrete can be accelerated again, the initial setting time of shotcrete can be reduced, and the engineering reliability is improved.

[0003] For concrete construction in cold regions, due to the difference between the concrete temperature and the external air temperature, heat exchange will occur between the concrete and the surrounding environment. When the environmental temperature is very low, this heat exchange will quickly reduce the temperature of the concrete. For freshly mixed concrete, the rate of temperature reduction determines the magnitude of the hydration temperature. The faster the temperature drops, the slower the growth of concrete strength. When the concrete is frozen prematurely, the strength will no longer increase, and the free water remaining in the concrete is also higher. The frost heaving force after freezing is greater, and the concrete is prone to damage. The main reason for the reduction of concrete strength is that the volume of water increases after freezing, and the frost heaving stress increases accordingly, resulting in cracks and damage to the concrete structure. Therefore, when pouring concrete in cold regions, a pouring anti-freezing device is required. However, when the existing concrete pouring anti-freezing devices are in use, most of them add anti-freezing agents or use hot steam to stir the concrete, etc. During the transportation and pouring process of the concrete, the temperature will be relatively low, affecting the pouring quality.

[0004] In view of this, the present invention is specifically proposed. By the principle of microwave irradiation, the setting of concrete can be accelerated, and the temperature of the concrete can be increased, playing an anti-freezing role when pouring concrete in cold regions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is aimed at the deficiencies in the above-mentioned prior art. A method for microwave-assisted setting of primary support concrete in tunnels and anti-freezing in cold regions of the present invention includes the following steps:

[0006] Excavate the heading face of a highway tunnel, and pre-clean the rock surface in advance to remove substances such as dust and rock debris existing on the surface of the surrounding rock, effectively preventing the influence of external factors on the shotcrete work.

[0007] Carry out initial shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate through the waveguide hydraulic cylinder and the support plate hydraulic cylinder respectively, adjust the longitudinal lengths of the waveguide and the support plate to be appropriate, adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When spraying concrete, initially spray concrete through the spray pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. During construction, different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions.

[0008] Stop the initial shotcrete and microwave irradiation after reaching the standard.

[0009] Drive tunnel bolts, install steel mesh and steel supports.

[0010] Carry out the second shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate through the waveguide hydraulic cylinder and the support plate hydraulic cylinder respectively, adjust the longitudinal lengths of the waveguide and the support plate to be appropriate, adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When spraying concrete, initially spray concrete through the spray pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. During construction, different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions. First, fill the gap between the arch frame and the surrounding rock with concrete, and then start the spraying work from around the arch frame and gradually spray towards the space between the arch frames, so that the concrete completely covers the steel mesh. Until the spraying is completed, turn off the microwave device, move the entire device to the position where the installation of the next bolt, steel mesh and steel support is completed, repeat the fifth step, and carry out the initial support of the next section of the tunnel.

[0011] After reaching the standard, move to the completion point of the excavation of the next heading face. After the shotcrete is completed, promptly cure the concrete, which can effectively ensure its quality and service life.

[0012] The present invention provides a method for microwave-assisted solidification of the primary support concrete in tunnels and anti-freezing in cold regions. On the upper side of the outer part of the housing, a waveguide and a support plate are installed. The waveguide is controlled to expand and contract by a waveguide hydraulic cylinder, and the waveguide can expand and contract longitudinally. The support plate is controlled to expand and contract by a support plate hydraulic cylinder, and the support plate can expand and contract longitudinally to cope with different heights. There are hinge points on the upper part of the support plate, which can be fixed or rotated. A flange is provided at the end of the waveguide, and a quartz sheet is provided in the inner circle of the flange. A front decoupling hook and a rear decoupling hook are respectively installed at the front and rear of the outer part of the housing. The front decoupling hook and the rear decoupling hook are for the convenience of transporting the device. Four wheels are installed on the lower side of the outer part of the housing, and four hydraulic support feet are installed at the four corners of the outer part of the housing. When the device is working, the hydraulic support feet are lowered to prevent the device from slipping and losing its center of gravity during the spraying of concrete. The spraying pipe is fixed on the support plate by a buckle. The rear end of the spraying pipe is connected to a concrete spraying machine, and a nozzle is installed at the front end of the spraying pipe for spraying concrete. The direction of the nozzle can be controlled by adjusting the angle of the support plate. The housing and the control panel are connected by a control panel rod. The control panel can be folded and retracted outside the housing through the control panel rod to reduce the space occupied by the device.

[0013] Further settings are as follows:

[0014] The control panel can control the microwave device, the waveguide hydraulic cylinder, the support plate hydraulic cylinder, and the hydraulic support feet. The microwave device is built into the housing. The microwave device includes a microwave power supply, a power controller, a transformer, a water circulation cooling system, a magnetron, and a three-pin tuner. The power controller, the transformer, the water circulation cooling system, the magnetron, and the three-pin tuner are connected to the control panel through the microwave power supply. The power controller can control the power of the magnetron, the transformer can control the voltage of the magnetron, the water circulation cooling system can cool the transformer, the three-pin tuner can reduce microwave loss, and the three-pin tuner is connected to the waveguide, and the microwave is emitted through the waveguide.

[0015] The beneficial effects of the present invention are as follows:

[0016] a. The present invention adopts the method of irradiating the primary support concrete in tunnels with microwaves, which can reduce the initial setting time of the sprayed concrete, improve the reliability of the project, and has a novel method and certain practicality.

[0017] b. The present invention uses microwaves to heat the primary support concrete in tunnels, increases the internal temperature after concrete pouring, effectively prevents the concrete from freezing, and improves the pouring quality.

[0018] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0019] Figure 1This is the flowchart of the implementation method of the present invention.

[0020] Figure 2 This is the device diagram of the embodiment of the present invention.

[0021] Figure 3 This is the control schematic diagram of the control panel of the present invention.

[0022] Description of the markings in the figure: 1. Housing; 2. Waveguide; 3. Flange; 4. Injection pipe; 5. Nozzle; 6. Support plate; 7. Buckle; 8. Waveguide hydraulic cylinder; 9. Support plate hydraulic cylinder; 10. Wheel; 11. Hydraulic support foot; 12. Front decoupling hook; 13. Rear decoupling hook; 14. Control panel; 15. Control panel rod; 16. Microwave device; 1601. Microwave power supply; 1602. Power controller; 1603. Transformer; 1604. Water circulation cooling system; 1605. Magnetron; 1606. Three-pin tuner. Detailed implementation manners

[0023] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0024] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. 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.

[0025] Please refer to Figures 1-3 , the present invention provides a technical solution: a method for microwave-assisted initial support concrete solidification and cold region anti-freezing in tunnels, including: 1. Housing; 2. Waveguide; 3. Flange; 4. Injection pipe; 5. Nozzle; 6. Support plate; 7. Buckle; 8. Waveguide hydraulic cylinder; 9. Support plate hydraulic cylinder; 10. Wheel; 11. Hydraulic support foot; 12. Front decoupling hook; 13. Rear decoupling hook; 14. Control panel; 15. Control panel rod; 16. Microwave device; 1601. Microwave power supply; 1602. Power controller; 1603. Transformer; 1604. Water circulation cooling system; 1605. Magnetron; 1606. Three-pin tuner.

[0026] A waveguide 2 and a support plate 6 are installed on the upper side of the exterior of the housing 1. The waveguide 2 is controlled to extend and retract by a waveguide hydraulic cylinder 8. The waveguide 2 can extend and retract longitudinally. The support plate 6 is controlled to extend and retract by a support plate hydraulic cylinder 9. The support plate 6 can extend and retract longitudinally to cope with different heights. There are hinge points on the upper part of the support plate 6, which can be fixed or rotated. A flange 3 is provided at the end of the waveguide 2, and a quartz sheet is provided inside the inner ring of the flange 3.

[0027] A front decoupling hook 12 and a rear decoupling hook 13 are respectively installed on the front and rear of the exterior of the housing 1. The front decoupling hook 12 and the rear decoupling hook 13 are for the convenience of transporting the device.

[0028] Four wheels 10 are installed on the lower side of the exterior of the housing. Four hydraulic support feet 11 are installed at the four corners of the exterior of the housing 1. When the device is working, the hydraulic support feet 11 are lowered to prevent the device from slipping and losing stability of the center of gravity during the spraying of concrete.

[0029] The spray pipe 4 is fixed on the support plate by a buckle 7. The rear end of the spray pipe 4 is connected to a concrete spraying machine. A nozzle 5 is installed at the front end of the spray pipe 4 for spraying concrete. The direction of the nozzle 5 can be controlled by adjusting the angle of the support plate 6.

[0030] The housing 1 is connected to the control panel 14 by a control panel rod 15. The control panel 14 can be folded and retracted outside the housing 1 through the control panel rod 15 to reduce the space occupied by the device.

[0031] The control panel 14 can control the microwave device 16, the waveguide hydraulic cylinder 8, the support plate hydraulic cylinder 9 and the hydraulic support feet 11. The microwave device 16 is built into the housing 1. The microwave device 16 includes a microwave power supply 1601, a power controller 1602, a transformer 1603, a water circulation cooling system 1604, a magnetron 1605 and a three-pin tuner 1606. The power controller 1602, the transformer 1603, the water circulation cooling system 1604, the magnetron 1605 and the three-pin tuner 1606 are connected to the control panel 14 through the microwave power supply 1601. The power controller 1602 can control the power of the magnetron 1605. The transformer 1603 can control the voltage of the magnetron 1605. The water circulation cooling system 1604 can cool the transformer 1603. The three-pin tuner 1606 can reduce microwave loss. The three-pin tuner 1606 is connected to the waveguide 2, and microwaves are emitted through the waveguide 2.

[0032] A method for microwave-assisted initial support concrete solidification and cold region anti-freezing in tunnels of the present invention includes the following steps:

[0033] S1: Excavate the tunnel face of the highway tunnel, and pre-clean the rock face to remove substances such as dust and rock debris on the surface of the surrounding rock, effectively preventing the influence of external factors on the shotcrete work.

[0034] S2: Conduct initial shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate respectively through the waveguide hydraulic cylinder and the support plate hydraulic cylinder, adjust the longitudinal lengths of the waveguide and the support plate to be appropriate, and adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When shotcreting, conduct initial shotcrete through the shotcrete pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. Different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions during construction.

[0035] S3: Stop the initial shotcrete and microwave irradiation after reaching the standard.

[0036] S4: Drive in tunnel bolts, install steel mesh and steel supports.

[0037] S5: Conduct second shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate respectively through the waveguide hydraulic cylinder and the support plate hydraulic cylinder, adjust the longitudinal lengths of the waveguide and the support plate to be appropriate, and adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When shotcreting, conduct initial shotcrete through the shotcrete pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. Different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions during construction. First, fill the gap between the arch frame and the surrounding rock with concrete, and then start the shotcrete work from around the arch frame and gradually spray towards between the arch frames to make the concrete completely cover the steel mesh until the shotcrete is completed. Turn off the microwave device, move the entire device to the position where the installation of the next bolt, steel mesh and steel support is completed, repeat the fifth step, and conduct the initial support of the next section of the tunnel.

[0038] S6: Move to the completion point of the excavation of the next tunnel face after reaching the standard. Cure the concrete in time after the shotcrete is completed, which can effectively ensure its quality and service life.

[0039] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for microwave-assisted solidification of primary support concrete in tunnels and freeze protection in cold regions, characterized in that The method includes the following steps: S1: Excavate the tunnel face of the highway tunnel. First, clean the rock surface to remove dust and rock debris on the surface of the surrounding rock, effectively preventing the influence of external factors on the shotcrete work; S2: Conduct primary shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate through the waveguide hydraulic cylinder and the support plate hydraulic cylinder respectively, so that the axial length of the waveguide reaches an appropriate length. Adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When spraying concrete, spray the primary shotcrete through the spray pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. During construction, different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions; S3: Stop the primary shotcrete and microwave irradiation after reaching the standard; S4: Drive in tunnel bolts, install steel mesh and steel supports; S5: Conduct secondary shotcrete and microwave irradiation. Adjust the angles of the waveguide and the support plate through the waveguide hydraulic cylinder and the support plate hydraulic cylinder respectively, so that the axial length of the waveguide reaches an appropriate length. Adjust the angle of the upper hinge point of the support plate to keep the nozzle horizontal. When spraying concrete, spray the primary shotcrete through the spray pipe and the nozzle in the order from bottom to top and from wall to arch. At the same time, emit microwaves through the waveguide to heat and reinforce the concrete. During construction, different microwave powers and microwave voltages should be adopted according to different concrete strengths and different construction conditions. First, fill the gap between the arch and the surrounding rock with concrete, and then start spraying from around the arch and gradually spray towards the space between the arches, so that the concrete completely covers the steel mesh until the spraying is completed. Turn off the microwave device, move the entire device to the position where the installation of the next bolt, steel mesh and steel support is completed, repeat the fifth step, and conduct the initial support of the next section of the tunnel; S6: Move to the completion point of the excavation of the next tunnel face after reaching the standard. Cure the concrete in time after the shotcrete is completed, which can effectively ensure its quality and service life.

2. A method for microwave-assisted setting of primary support concrete in tunnels and anti-freezing in cold regions according to claim 1, characterized in that, The method for strengthening the initial support concrete of the tunnel is microwave irradiation. The microwave frequency band used is in the range of 1 GHz - 15 GHz, and the microwave power is 0.5 - 10 kW.

3. A method for microwave-assisted setting of primary support concrete in tunnels and anti-freezing in cold regions according to claim 1, characterized in that, The microwave device includes a microwave power supply, a power controller, a transformer, a water circulation cooling system, a magnetron and a three-pin tuner; the power controller can control the power of the magnetron, the transformer can control the voltage of the magnetron, the water circulation cooling system can cool the transformer, the three-pin tuner can reduce microwave loss, the three-pin tuner is connected to the waveguide, and the microwave is emitted through the waveguide.

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