Long-distance small-section tunnel concrete construction system and method

Abstract

The invention discloses a long-distance small-section tunnel concrete construction system and method. The system comprises a raw material premixing and conveying subsystem arranged outside a tunnel and a working face mixing subsystem matched with the raw material premixing and conveying subsystem and arranged on a tunnel working face. The raw material premixing and conveying subsystem comprises a premixing mechanism and a powder conveying mechanism; the method comprises the following steps: 1, feeding aggregate; 2, premixing to form suspension slurry; 3, the suspended slurry is pumped to a working face mixing subsystem; 4, pneumatic conveying of the powder cement and the mineral admixture; and 5, performing on-site mixing on the tunnel working face to finish concrete pumping construction. The conventional one-time concrete stirring and discharging thought is broken through, the concrete stirring step is divided into a raw material premixing and conveying system outside the tunnel and a working face stirring system located on the working face of the tunnel, the stirred concrete can be directly used for tunnel face construction, continuous operation of construction can be guaranteed, and the construction efficiency is improved. And the concrete construction quality cannot be influenced by long-time transportation of the concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete construction, and in particular relates to a long-distance small-section tunnel concrete construction system and method. Background Art

[0002] In tunnel engineering, processes such as shotcrete support and secondary lining require large quantities of concrete. For long tunnels (such as the approximately 30-40km long diversion tunnel), the long length of the project, the small excavation cross-section, and the constraints of the terrain and geography make it impossible to transport concrete over long distances using traditional concrete tankers. Furthermore, conventional concrete pumping distances are limited to approximately 300-800m, making this impossible.

[0003] Due to the small cross-section of the tunnel, the transportation and stacking of materials are extremely difficult, making it difficult to mix and prepare concrete along the construction route. Currently, construction often uses small trains pulling tank cars to transport the mixed concrete to the working surface. However, due to the narrow tunnel cross-section and complex single-track conditions, transportation speeds are slow and the intervals between cars are long (the front car must exit before the rear car can enter). This leads to frequent construction interruptions and a serious lack of continuity, seriously affecting construction progress. Furthermore, concrete segregates and settles during long transportation periods. This results in significant slump loss over time, poor pumpability, and cold joints during construction, seriously affecting construction quality. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a long-distance small-section tunnel concrete construction system in response to the deficiencies in the above-mentioned prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a long-distance small-section tunnel concrete construction system, characterized in that it includes a raw material premixing and conveying subsystem arranged outside the tunnel and a working surface mixing subsystem coordinated with the raw material premixing and conveying subsystem and arranged on the tunnel working surface, the raw material premixing and conveying subsystem includes a premixing mechanism and a powder conveying mechanism, the premixing mechanism includes a feeding bin for receiving aggregates of different particle sizes and a belt conveyor located at the lower side of the feeding bin and for receiving aggregates, the transport end of the belt conveyor is provided with an intelligent pulping machine, a water tank, a first admixture storage tank and the second admixture storage tank are both connected to the intelligent pulping machine, the mixing tank feed port is connected to the intelligent pulping machine discharge end, the mixing tank discharge port is connected to the slurry pump, the slurry pump is connected to the working face mixing subsystem through a conveying pipeline, the powder conveying mechanism includes a mineral admixture silo and a cement silo connected to the powder conveying pipeline, the Roots blower unit is connected to the working face mixing subsystem through a powder conveying pipeline; the working face mixing subsystem includes a sand and gravel slurry transfer silo, a cement transfer silo, a mineral admixture transfer silo and a collection silo, the concrete pump feed end is connected to the collection silo outlet, and the concrete pump discharge end pumps concrete through a pump pipe.

[0006] The above-mentioned long-distance, small-section tunnel concrete construction system is characterized in that: silo metering devices are respectively provided at different outlet positions of the feeding silo, the feeding end of the belt conveyor is connected to the outlet of the silo metering device, and coarse and fine aggregates of different particle sizes are added to the top of the feeding silo by a forklift; a first flow controller is provided on the pipeline connecting the water tank, the first admixture storage tank, the second admixture storage tank and the intelligent pulping machine; the first admixture includes an air entraining agent or a water reducer, and the second admixture includes a thickener or a suspending agent, and the thickener includes one or more of methyl cellulose, polyvinyl alcohol, silica fume, and sodium polyacrylate.

[0007] The above-mentioned long-distance small-section tunnel concrete construction system is characterized in that a stirrer is provided on the mixing tank.

[0008] The above-mentioned long-distance small-section tunnel concrete construction system is characterized in that: the discharge end of the mineral admixture silo is provided with a first metering device, and the discharge end of the cement silo is provided with a second metering device; the discharge end of the mineral admixture silo can also be connected to the intelligent pulping machine.

[0009] The above-mentioned long-distance small-section tunnel concrete construction system is characterized in that: the slurry pump is connected to the sand and gravel slurry transfer bin of the working face mixing subsystem through a conveying pipeline, and the Roots blower unit is connected to the cement transfer bin and mineral admixture transfer bin of the working face mixing subsystem through a powder conveying pipeline.

[0010] The above-mentioned long-distance small-section tunnel concrete construction system is characterized in that: the discharge end of the sand and gravel slurry transfer bin is provided with a third metering device, the discharge end of the cement transfer bin is provided with a fourth metering device, the discharge end of the mineral admixture transfer bin is provided with a fifth metering device, and a mixer is provided on the material collection bin.

[0011] The above-mentioned long-distance small-section tunnel concrete construction system is characterized in that the working face mixing subsystem is installed on a mobile cart, and the mobile cart is also provided with a water supply tank and a first admixture replenishment tank, and a second flow controller is provided on the pipeline connecting the water supply tank and the first admixture replenishment tank to the material silo.

[0012] At the same time, the present invention also discloses a method for concrete construction of a long-distance small-section tunnel, which is characterized in that the method comprises the following steps: Step 1: Aggregate loading: According to the component requirements of the concrete mix ratio, a forklift delivers aggregates of different particle sizes to different positions of the feeding silo. The corresponding silo metering device at the bottom completes the metering and batching. The measured coarse and fine aggregates are then fed into the intelligent pulping machine as a whole via a belt conveyor. Step 2: Premixing to form a suspended slurry: According to the concrete mix ratio requirements, add part or all of the water reducer, air entraining agent, and water component originally in the concrete mix ratio, and add the designed amount of thickener or suspending agent. After the admixtures and water are measured by the first flow controller, they enter the intelligent slurry making machine and are mixed with the coarse and fine aggregates to form a uniform and stable suspended slurry; Step 3: The suspended slurry is pumped to the working surface mixing subsystem; Step 4, pneumatically conveying powdered cement and mineral admixtures: the powdered cement is weighed by the first metering device at the bottom of the silo and then enters the powdered material conveying pipeline. The particle size of the powdered cement is small. The Roots blower group at the rear blows air into the conveying pipeline, and the powdered cement is conveyed to the cement transfer bin in the working face mixing system by wind power; the mineral admixture is weighed by the second metering device at the bottom of the silo and then enters the powdered material conveying pipeline. The particle size of the mineral admixture is small. The Roots blower group at the rear blows air into the conveying pipeline, and the mineral admixture is conveyed to the mineral admixture transfer bin in the working face mixing system by wind power; Step 5: On-site mixing of materials at the tunnel working face completes concrete pumping construction: According to the concrete mix ratio weight requirements, the sand and gravel transfer silo is measured by the third metering device at the bottom, and the cement and mineral admixtures are respectively fed into the collection silo for mixing. Since all or part of the original water reducer, air entraining agent, and water component dosage in the concrete mix ratio are added to the sand and gravel slurry in the early stage, the insufficient components of the water reducer and air entraining agent in the first admixture can be supplemented according to the concrete mix ratio requirements, and the concrete is weighed through the water replenishment tank and the first admixture replenishing water tank and then fed into the collection silo for mixing. The mixed concrete is then pumped through the concrete pump and pump pipe to complete the concrete pumping construction.

[0013] Compared with the prior art, the present invention has the following advantages: 1. The process of the present invention is simple, and requires less new equipment than the existing process. It can greatly reduce the time and cost of concrete transportation, improve construction efficiency and construction quality, and break the conventional idea of mixing and discharging concrete in one go. The concrete mixing steps are innovatively divided into two parts. The first step is the raw material premixing and conveying system. The entire system is completed in a spacious place outside the tunnel or in the expanded cavern of the tunnel entrance, and mainly completes the classification, mixing and conveying of raw materials; the second step is the working face mixing system, which is located on the working face of the tunnel. The mixed concrete can be directly used for the face construction, which can ensure continuous operation of the construction, greatly improve construction efficiency, and will not cause problems such as long-term concrete transportation affecting the quality of concrete construction.

[0014] 2. The present raw material premixing and delivery system utilizes some or all of the existing water reducer, air entraining agent, and water content in the concrete mix, along with a small amount of thickener and / or suspending agent. This is then mixed with coarse and fine aggregate to form a uniform, stable suspended slurry that can withstand certain external forces and remain suspended in the pipeline for a period without settling. Because no cement binder is added, the mixed slurry will not coagulate or clog the pipeline, making it suitable for long-distance delivery.

[0015] 3. The present invention transports the components in concrete according to their properties. The powder is transported by wind, and the coarse and fine aggregates are made into a uniform and stable suspended slurry with water and admixture components, which is convenient for pipeline transportation. After being transported to the working surface, the concrete mixing is finally completed.

[0016] 4. Compared with the original mix components, the present invention only adds a small amount of thickener and suspending agent, and the total amount added is less than 0.1% of the total amount of concrete, which will not affect the workability and strength of the concrete. In addition, due to the addition of a small amount of thickener, the concrete has a significant improvement in workability on the one hand, and on the other hand, it can reduce the rebound rate and segregation settlement during spray-mixing construction, which has a significant improvement on concrete construction.

[0017] 5. The sand and gravel slurry and powder materials of the present invention are transported by detachable pipes, which will not cause pollution and save floor space. They are also easy to disassemble and can be spliced and added in real time as the tunnel construction distance is extended. The working face mixing subsystem is installed on a mobile trolley and is directly located on the tunnel construction working face, and can be flexibly moved according to construction needs.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structural connection of the system of the present invention.

[0020] Figure 2 4 is a flowchart of the method of the present invention.

[0021] Description of the accompanying drawings: 1—Raw material premixing and conveying subsystem; 2—Working surface mixing subsystem; 3—Feeding silo; 4—silo metering device; 5—belt conveyor; 6—water tank; 7—first admixture storage tank; 8—second admixture storage tank; 9—first flow controller; 10—Intelligent pulping machine; 11—Mixing tank; 12—Agitator; 13—slurry pump; 14—transport pipeline; 15—mineral admixture silo; 16 - cement silo; 17 - first metering device; 18 - second metering device; 19—Roots blower unit; 20—Powder conveying pipeline; 21—Mobile trolley; 22-sand and gravel slurry transfer warehouse; 23-cement transfer warehouse; 24-mineral admixture transfer warehouse; 25—third metering device; 26—fourth metering device; 27—fifth metering device; 28 - mixer; 29 - concrete pump; 30 - water tank; 31—first admixture replenishing tank; 32—second flow controller. DETAILED DESCRIPTION

[0022] like Figure 1 As shown, a long-distance small-section tunnel concrete construction system according to the present invention comprises a raw material premixing and conveying subsystem 1 arranged outside the tunnel and a working surface mixing subsystem 2 coordinated with the raw material premixing and conveying subsystem 1 and arranged on the tunnel working surface. The raw material premixing and conveying subsystem 1 comprises a premixing mechanism and a powder conveying mechanism. The premixing mechanism comprises a feeding bin 3 for receiving aggregates of different particle sizes and a belt conveyor 5 located at the lower side of the feeding bin 3 and for receiving aggregates. An intelligent pulping machine 10 is provided at the transport end of the belt conveyor 5. The water tank 6, the first admixture storage tank 7 and the second admixture storage tank 8 are all connected to the intelligent pulping machine 10. The feed port of the mixing tank 11 is connected to the discharge end of the intelligent pulping machine 10, and the discharge port of the mixing tank 11 is connected to the slurry pump 13. The slurry pump 13 is connected to the working face mixing subsystem 2 through the conveying pipeline 14. The powder conveying mechanism includes a mineral admixture silo 15 and a cement silo 16 connected to the powder conveying pipeline 20. The Roots blower unit 19 is connected to the working face mixing subsystem 2 through the powder conveying pipeline 20; the working face mixing subsystem 2 includes a sand and gravel slurry transfer silo 22, a cement transfer silo 23, a mineral admixture transfer silo 24 and a collection silo. The feed end of the concrete pump 29 is connected to the outlet of the collection silo, and the discharge end of the concrete pump 29 pumps concrete through a pump pipe.

[0023] In this embodiment, the feeding silo 3 is respectively provided with a silo metering device 4 at different outlet positions, the feeding end of the belt conveyor 5 is connected to the outlet of the silo metering device 4, and coarse and fine aggregates of different particle sizes are thrown into the top of the feeding silo 3 by a forklift; a first flow controller 9 is provided on the pipeline connecting the water tank 6, the first admixture storage tank 7 and the second admixture storage tank 8 to the intelligent pulping machine 10; the first admixture includes an air entraining agent or a water reducer, and the second admixture includes a thickener or a suspending agent, and the thickener includes one or more of methyl cellulose, polyvinyl alcohol, silica fume, and sodium polyacrylate.

[0024] In this embodiment, an agitator 12 is provided on the mixing tank 11 .

[0025] In this embodiment, the discharge end of the mineral admixture silo 15 is provided with a first metering device 17 , and the discharge end of the cement silo 16 is provided with a second metering device 18 ; the discharge end of the mineral admixture silo 15 can also be connected to the intelligent pulping machine 10 .

[0026] In this embodiment, the slurry pump 13 is connected to the sand and gravel slurry transfer bin 22 of the working face mixing subsystem 2 through the conveying pipeline 14, and the Roots blower unit 19 is connected to the cement transfer bin 23 and the mineral admixture transfer bin 24 of the working face mixing subsystem 2 through the powder conveying pipeline 20.

[0027] In this embodiment, the discharge end of the sand and gravel slurry transfer bin 22 is provided with a third metering device 25, the discharge end of the cement transfer bin 23 is provided with a fourth metering device 26, the discharge end of the mineral admixture transfer bin 24 is provided with a fifth metering device 27, and a mixer 28 is provided on the collection bin.

[0028] In this embodiment, the working face mixing subsystem 2 is installed on a mobile cart 21, and a water replenishment tank 30 and a first additive replenishment tank 31 are also provided on the mobile cart 21. A second flow controller 32 is provided on the pipeline connecting the water replenishment tank 30 and the first additive replenishment tank 31 to the material collection bin.

[0029] It should be noted that the conveying pipeline 14 and the powder conveying pipeline 20 are both detachable, and the pipelines are connected by flanges or quick connectors, which can ensure stable connectivity of the pipelines while allowing them to be quickly disassembled.

[0030] One or more Roots blower units 19 are provided and can be opened in real time according to the conveying distance and pressure.

[0031] The working face mixing system 2 is located at the tunnel face. All the equipment of the system is concentrated on the mobile trolley 21 and can move freely with the mobile trolley 21 as a whole.

[0032] like Figure 2 The method for concrete construction of a long-distance small-section tunnel shown includes the following steps: Step 1: Aggregate loading: According to the component requirements in the mix ratio of concrete production, a forklift delivers aggregates of different particle sizes to different positions of the feeding silo 3. The materials are metered and batched by the corresponding silo metering device 4 at the bottom. The measured coarse and fine aggregates are fed as a whole into the intelligent pulping machine 10 via the belt conveyor 5; Step 2: Premixing to form a suspended slurry: According to the concrete mix ratio requirements, add part or all of the water reducer, air entraining agent, and water component originally in the concrete mix ratio, and add the designed amount of thickener or suspending agent. After the admixtures and water are measured by the first flow controller 9, they enter the intelligent pulping machine 10 and are mixed with the coarse and fine aggregates to form a uniform and stable suspended slurry; The mineral admixture can also be weighed by the metering system and then enter the pulping machine. The stirred slurry is sent to the finished product mixing tank 11 for temporary storage. The mixing tank 11 is equipped with a stirrer 12 to continuously stir the suspended slurry.

[0033] Step 3: The suspended slurry is pumped to the working surface mixing subsystem; The finished slurry enters the slurry pump, which can pump about 10km. Since no cement or other gelling materials are added to the sand and gravel slurry, the mixed slurry will not coagulate and can form a uniform and stable suspended slurry. It can also resist a certain external force and can be stably suspended in the pipeline for a period of time without settling, and will not cause pipe blockage problems. It can meet the needs of long-distance slurry transportation. The sand and gravel slurry is sent to the sand and gravel slurry transfer silo 22 in the working face mixing system 2 through the detachable conveying pipeline 14. The conveying pipeline 14 can be spliced and extended in real time as the tunnel construction distance is extended; when the tunnel construction distance is longer than 10km, a transfer silo and relay pump can be added in the middle to meet the long-distance pumping needs.

[0034] Step 4: Pneumatically conveying powdered cement and mineral admixtures: The powdered cement is weighed by the first metering device 17 at the bottom of the silo and then enters the powder conveying pipeline 20. The powdered cement has a small particle size. The Roots blower unit 19 at the rear blows air into the conveying pipeline, and the powdered cement is conveyed to the cement transfer bin 23 in the working face mixing system 2 by wind power. The mineral admixture is weighed by the second metering device 18 at the bottom of the silo and then enters the powder conveying pipeline 20. The mineral admixture has a small particle size. The Roots blower unit 19 at the rear blows air into the conveying pipeline, and the mineral admixture is conveyed to the mineral admixture transfer bin 24 in the working face mixing system 2 by wind power. The powder conveying pipeline is also detachable and can be spliced in real time as the tunnel excavation distance is extended. When the tunnel construction distance gradually increases and the wind conveying pressure is insufficient, a booster pump can be added at the rear, or a transfer silo and wind conveying equipment can be set up at the terminal of the conveying line to meet the needs of long-distance powder transportation.

[0035] Step 5: On-site mixing of materials at the tunnel working face completes concrete pumping construction: According to the concrete mix ratio weight requirements, the sand and gravel transfer silo is measured by the third metering device 25 at the bottom, and the cement and mineral admixtures are respectively metered and enter the collection silo for mixing. Since all or part of the water reducer, air entraining agent, and water components originally added to the concrete mix ratio are used in the early stage of the sand and gravel slurry, the insufficient components of the water reducer and air entraining agent in the first admixture can be supplemented according to the concrete mix ratio requirements, and the concrete is weighed through the water replenishment tank 30 and the first admixture replenishment water tank 32 and then sent to the collection silo for mixing. The mixed concrete is then pumped through the concrete pump 29 and the pump pipe to complete the concrete pumping construction.

[0036] Since the entire mixing system is located at the tunnel face, the mixed concrete can be directly constructed and applied to the working face. The concrete is mixed and used immediately, and the short transportation distance will not cause segregation and settlement, which will affect the construction quality.

[0037] In addition, compared with the original mix components, the existing concrete mix components only add a small amount of thickeners and suspending agents, and the total amount added is less than 0.1% of the total amount of concrete, which will not affect the workability and strength of the concrete. Moreover, due to the addition of a small amount of thickeners, the concrete has a significant improvement in workability on the one hand, and on the other hand, it can reduce the rebound rate and segregation settlement during spray-mixing construction, which has a significant improvement effect on concrete construction.

[0038] During actual production, the Roots blower unit 19 and the slurry pump 29 can be started in advance according to the on-site production situation, and the equipment transportation capacity can be adjusted to stably and continuously supply materials to the transfer bin of the working face. When there is a certain amount of material stored in the transfer bin, the concrete mixer 28 is started to start concrete mixing production. Material buffer bins are provided on the top of the concrete mixer 28 and the concrete pump 29. By matching the production system, continuous mixing and pumping of concrete can be achieved, thereby realizing continuous concrete pumping construction. The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A long-distance, small-section tunnel concrete construction system, characterized by: The invention comprises a raw material premixing and conveying subsystem (1) arranged outside the tunnel and a working face mixing subsystem (2) coordinated with the raw material premixing and conveying subsystem (1) and arranged on the tunnel working face. The raw material premixing and conveying subsystem (1) comprises a premixing mechanism and a powder conveying mechanism. The premixing mechanism comprises a feeding bin (3) for receiving aggregates of different particle sizes and a belt conveyor (5) located below the feeding bin (3) and for receiving aggregates. An intelligent pulping machine (10) is provided at the transport end of the belt conveyor (5). A water tank (6), a first admixture storage tank (7) and a second admixture storage tank (8) are all connected to the intelligent pulping machine (10). The feed port of the mixing tank (11) is connected to the outlet of the intelligent pulping machine (10). The material end is connected, the material outlet of the mixing tank (11) is connected to the slurry pump (13), the slurry pump (13) is connected to the working face mixing subsystem (2) through the conveying pipeline (14), the powder conveying mechanism includes a mineral admixture silo (15) and a cement silo (16) connected to the powder conveying pipeline (20), and the Roots blower unit (19) is connected to the working face mixing subsystem (2) through the powder conveying pipeline (20); the working face mixing subsystem (2) includes a sand and gravel slurry transfer silo (22), a cement transfer silo (23), a mineral admixture transfer silo (24) and a collection silo, the feed end of the concrete pump (29) is connected to the outlet of the collection silo, and the discharge end of the concrete pump (29) pumps concrete through a pump pipe.

2. A long-distance, small-section tunnel concrete construction system according to claim 1, characterized in that: The feeding bin (3) is provided with a silo metering device (4) at different outlet positions, the feeding end of the belt conveyor (5) is connected to the outlet of the silo metering device (4), and coarse and fine aggregates of different particle sizes are fed into the top of the feeding bin (3) by a forklift; a first flow controller (9) is provided on a pipeline connecting the water tank (6), the first admixture storage tank (7), and the second admixture storage tank (8) with the intelligent pulping machine (10); the first admixture includes an air entraining agent or a water reducing agent, and the second admixture includes a thickener or a suspending agent, and the thickener includes one or more of methyl cellulose, polyvinyl alcohol, silica fume, and sodium polyacrylate.

3. A long-distance, small-section tunnel concrete construction system according to claim 1, characterized in that: The mixing tank (11) is provided with an agitator (12).

4. A long-distance, small-section tunnel concrete construction system according to claim 2, characterized in that: The discharge end of the mineral admixture silo (15) is provided with a first metering device (17), and the discharge end of the cement silo (16) is provided with a second metering device (18); the discharge end of the mineral admixture silo (15) can also be connected to the intelligent pulping machine (10).

5. A long-distance, small-section tunnel concrete construction system according to claim 1, characterized in that: The slurry pump (13) is connected to the sand and gravel slurry transfer bin (22) of the working face mixing subsystem (2) through a conveying pipeline (14), and the Roots blower unit (19) is connected to the cement transfer bin (23) and the mineral admixture transfer bin (24) of the working face mixing subsystem (2) through a powder conveying pipeline (20).

6. A long-distance, small-section tunnel concrete construction system according to claim 4, characterized in that: The discharge end of the sand and gravel slurry transfer bin (22) is provided with a third metering device (25), the discharge end of the cement transfer bin (23) is provided with a fourth metering device (26), the discharge end of the mineral admixture transfer bin (24) is provided with a fifth metering device (27), and the material collection bin is provided with a mixer (28).

7. A long-distance, small-section tunnel concrete construction system according to claim 1, characterized in that: The working face mixing subsystem (2) is installed on a mobile trolley (21). The mobile trolley (21) is also provided with a water replenishment tank (30) and a first admixture replenishment tank (31). A second flow controller (32) is provided on the pipeline connecting the water replenishment tank (30) and the first admixture replenishment tank (31) to the material collection bin.

8. A method for carrying out concrete construction of a long-distance, small-section tunnel using the system according to claim 6, characterized in that: The method comprises the following steps: Step 1: Aggregate loading: According to the component requirements in the mix ratio of concrete production, a forklift is used to feed aggregates of different particle sizes into different positions of the feeding bin (3). The aggregates are metered and batched by the corresponding bin metering device (4) at the bottom. The measured coarse and fine aggregates are fed as a whole into the intelligent pulping machine (10) via a belt conveyor (5); Step 2: Premixing to form a suspended slurry: According to the concrete mix ratio requirements, add part or all of the water reducer, air entraining agent, and water component dosage originally in the concrete mix ratio, and additionally add the designed amount of thickener or suspending agent. After the admixtures and water are metered by the first flow controller (9), they enter the intelligent pulping machine (10) and are mixed and stirred with the coarse and fine aggregates to form a uniform and stable suspended slurry; Step 3: The suspended slurry is pumped to the working surface mixing subsystem; Step 4: Pneumatically conveying powdered cement and mineral admixtures: The powdered cement is weighed by the first metering device (17) at the bottom of the silo and then enters the powdered material conveying pipeline (20). The particle size of the powdered cement is small. The Roots blower group (19) at the rear blows air into the conveying pipeline, and the powdered cement is conveyed by wind to the cement transfer bin (23) in the working face mixing system (2); the mineral admixture is weighed by the second metering device (18) at the bottom of the silo and then enters the powdered material conveying pipeline (20). The particle size of the mineral admixture is small. The Roots blower group (19) at the rear blows air into the conveying pipeline, and the mineral admixture is conveyed by wind to the mineral admixture transfer bin (24) in the working face mixing system (2); Step 5: On-site mixing of materials at the tunnel working face to complete concrete pumping construction: According to the concrete mix ratio weight requirement, the sand and gravel transfer silo is measured by the third metering device (25) at the bottom, and the cement and mineral admixtures are respectively fed into the collection silo for mixing. Since all or part of the water reducer, air entraining agent, and water components originally added to the concrete mix ratio are used in the early stage of the sand and gravel slurry, the insufficient components of the water reducer and air entraining agent in the first admixture can be supplemented according to the concrete mix ratio requirement, and the concrete is weighed through the water replenishing tank (30) and the first admixture replenishing water tank (32) and then fed into the collection silo for mixing. The mixed concrete is then pumped through the concrete pump (29) and the pump pipe to complete the concrete pumping construction.

Images