Tunnel primary support sprayed concrete partition quality control construction method

Abstract

The invention provides a tunnel primary support shotcrete partition quality control construction method. The method comprises the following steps that S1, a wet shotcrete manipulator is checked before running; s2, rock surface cleaning; s3, pipe moistening with mortar; s4, concrete index control; s5, shotcrete construction is carried out; according to the method, before wet spraying is started, mortar with the same proportion is sprayed to the arch crown part in advance, the roughness of a base body is increased, and the bonding effect is improved; firstly, the spraying vault position, the spraying angle and the spraying flow speed are controlled within a reasonable construction range, concrete springback is reduced, the spraying thickness each time is controlled to be about 50 mm, and it is guaranteed that the gravity of concrete is smaller than the cohesive force of the concrete; and after the concrete at the last vault part has strength, next spraying is carried out to ensure that the vault concrete does not fall off, spraying and accumulation of arch feet and arch shoulders of the lower step and the upper step can be carried out after each time of vault spraying, flow construction is formed, and the working efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to a construction method for zoning quality control of shotcrete for initial support of a tunnel. Background Art

[0002] When using the micro-step excavation method under weak surrounding rock geological conditions, the mechanized supporting solution uses a concrete wet spraying robot for initial support. When the traditional wet spraying process was used in the initial construction stage, the following technical problems were exposed:

[0003] (1) The single cycle process takes a long time, affecting the overall construction progress;

[0004] (2) The rebound rate of shotcrete is significantly high, which increases material loss;

[0005] (3) The support surface has poor flatness, insufficient local thickness, and the strength does not meet the design requirements.

[0006] Therefore, it is urgent to design a tunnel initial support shotcrete construction method to solve the current technical problems. Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention provides a zoning quality control construction method for shotcrete of initial support of tunnels, which has the advantages of short construction period, low safety risk, low construction cost and improved flatness of support surface.

[0008] The technical solution of the present invention is: a construction method for zoning quality control of shotcrete for initial support of a tunnel, comprising the following steps:

[0009] S1, inspection before wet spraying robot operation;

[0010] S2, rock face cleaning;

[0011] S3, mortar lubrication pipe;

[0012] S4, concrete index control;

[0013] S5, shotcrete construction;

[0014] The S5 includes the following steps:

[0015] S51, the rock face arch is divided into seven areas;

[0016] S52: Before starting wet spraying, pre-spray 10-20mm thick mortar with the same mix ratio from bottom to top to increase the base roughness;

[0017] S53, spray according to seven zones, and control the thickness of each spraying to 50mm±5mm;

[0018] S54, repeat S53 until the injection is completed;

[0019] S55, surface leveling.

[0020] Furthermore, in S51, the rock face arch portion is divided into seven areas: the arch crown, the left arch span, the left arch foot of the upper step, the right arch span, the right arch foot of the upper step, the left arch foot of the lower step, and the right arch foot of the lower step;

[0021] In S53, the injection order of the seven sections is: crown, left spandrel, left arch foot of upper step, crown, right spandrel, right arch foot of upper step, crown, left spandrel, left arch foot of lower step, crown, right spandrel, right arch foot of lower step.

[0022] Furthermore, in said S53, the dosage of the accelerating agent for concrete spraying in different areas of the seven sections is:

[0023] The arch crown is 8-10%, the left arch shoulder is 6-8%, the left arch foot of the upper step is 3-6%, the right arch shoulder is 6-8%, the right arch foot of the upper step is 3-6%, the left arch foot of the lower step is 3-6%, and the right arch foot of the lower step is 3-6%.

[0024] Furthermore, in S53, the concrete spraying wind pressure is controlled at 0.6-0.8 MPa; the spraying angle is controlled at 75-105°; the interval time between spraying of adjacent layers is recommended to be controlled at 10-15 minutes; and the spraying distance is 0.8-1.5 m.

[0025] Furthermore, the S1 includes the following steps:

[0026] The wet spraying robot is in place;

[0027] Complete the fixing of the front and rear legs, and the connection of the external power supply, air duct, and water pipe;

[0028] Start trial operation and debugging, extend the spray arm by operating the controller, start the air compressor and set the accelerator dosage at the same time;

[0029] After the trial run is completed, the spray head is installed.

[0030] Furthermore, the S2 includes the following steps:

[0031] Before spraying concrete, use a high-pressure air gun to clean the rock surface after blasting.

[0032] Furthermore, the step S3 includes the following steps:

[0033] Use mortar of the same grade to lubricate the pipes before spraying concrete;

[0034] When lubricating the pipe, the pumping displacement is controlled at 15m 3 / h, the dosage of accelerator is adjusted to 10%.

[0035] Furthermore, the S4 includes the following steps:

[0036] The slump of concrete is controlled within the range of 160-180mm;

[0037] The slump loss rate of concrete over time is ≤5%, and the waiting interval time of concrete transport tankers during construction is ≤90 minutes.

[0038] Furthermore, the S55 includes the following steps:

[0039] Use tunnel spray-mix scraper to install it on the spraying machine nozzle;

[0040] After each truckload of material is sprayed, use the tunnel spray-mixing scraper to clean the concrete bonded on the spandrels and arch supports;

[0041] The bonded concrete at the arch foot is cleaned manually using a manual floor shovel.

[0042] Furthermore, the tunnel spray-mixing scraper includes a sleeve, one end of which is symmetrically provided with a sleeve slot, the other end of which is fixedly provided with a compression spring, and the end of the compression spring which is away from the sleeve is fixedly provided with a scraper;

[0043] The manual floor shovel has a shovel plate, and one end of the shovel plate is fixedly provided with a rod body.

[0044] Beneficial effects of the present invention:

[0045] (1) In the present invention, mortar with the same proportion is pre-sprayed on the top of the arch before starting wet spraying to increase the roughness of the base and improve the bonding effect;

[0046] (2) First spray the dome position, control the spray angle and spray flow rate within a reasonable construction range to reduce concrete rebound, and control the thickness of each spray to about 50mm to ensure that the concrete's own gravity is less than the concrete's bonding force;

[0047] (3) When the concrete of the last arch has strength, the next spraying is carried out to ensure that the arch concrete does not fall. After each arch spraying, the arch foot and spandrel of the lower and upper steps can be sprayed and accumulated to form a continuous construction and improve work efficiency;

[0048] (4) Before construction, clean the rock surface after blasting to ensure that there is no residue on the rock surface and prevent the sprayed concrete from sticking to the residue and falling off. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of the method for zoning quality control construction method of shotcrete for initial support of tunnel in the present invention.

[0050] Figure 2This is a seven-part area diagram of the rock face arch in the present invention.

[0051] Figure 3 This is the cross-section distribution diagram of the accelerator dosage control in the present invention.

[0052] Figure 4 Schematic diagram of the injection angle force in the present invention.

[0053] Figure 5 This is the spray distance control diagram of the present invention.

[0054] Figure 6 It is a structural schematic diagram of the tunnel spray-mixing scraper in the present invention.

[0055] Figure 7 It is a structural schematic diagram of the manual floor shovel in the present invention.

[0056] Figure 8 This is a sequence diagram of multiple batches of arch frame injection in the present invention. DETAILED DESCRIPTION

[0057] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present invention, its application, or use. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present invention thorough and complete and to fully convey the scope of the present invention to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and numerical values set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0058] The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are simply used to distinguish different parts. Terms such as "include" or "comprising" mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0059] like Figure 1 As shown in the figure, the construction method of zoning quality control of shotcrete for initial support of tunnel includes the following steps:

[0060] S1, inspection before wet spraying robot operation;

[0061] S2, rock face cleaning;

[0062] S3, mortar lubrication pipe;

[0063] S4, concrete index control;

[0064] S5, shotcrete construction;

[0065] S5 includes the following steps:

[0066] S51, the rock face arch is divided into seven areas;

[0067] S52: Before starting wet spraying, pre-spray 10-20mm thick mortar with the same mix ratio from bottom to top to increase the base roughness, improve the bonding effect, and prevent rock bursts and rockfalls;

[0068] S53, spray according to seven zones, and control the thickness of each spraying to 50mm±5mm;

[0069] S54, repeat S53 until the injection is completed;

[0070] S55, surface leveling.

[0071] In the above embodiment, before starting wet spraying, mortar with the same proportion is pre-sprayed on the arch top to increase the roughness of the base and improve the bonding effect; the arch top position is sprayed first, and the spraying angle and spraying flow rate are controlled within a reasonable construction range to reduce the rebound of the concrete. The thickness of each spraying is controlled at about 50 mm to ensure that the self-gravity of the concrete is less than the bonding force of the concrete; when the concrete at the arch top position has strength after the previous spraying, the next spraying is carried out to ensure that the arch top concrete does not fall off. After each arch top spraying, the lower and upper steps, arch feet and arch shoulders can be sprayed and accumulated to form a continuous construction and improve work efficiency; before construction, the rock surface after blasting is cleaned to ensure that there is no residue on the rock surface to avoid the sprayed concrete sticking to the residue part and falling off.

[0072] In some embodiments, as Figure 2 As shown, in S51, the rock face arch portion is divided into seven areas: the arch crown, the left arch span, the left arch foot of the upper step, the right arch span, the right arch foot of the upper step, the left arch foot of the lower step, and the right arch foot of the lower step.

[0073] In some embodiments, in S53, in order to reduce the rebound rate of shotcrete and shorten the time-consuming spraying process, the spraying order of the seven-part area spraying is: crown, left spandrel, left arch foot of upper step, crown, right spandrel, right arch foot of upper step, crown, left spandrel, left arch foot of lower step, crown, right spandrel, right arch foot of lower step; the spraying thickness of each time is controlled at about 50 mm (such as 50 mm ± 5 mm), and this operation is repeated until the spraying is completed; if the concrete is in good condition, the spraying thickness can be increased by 50 to 70 mm, that is, the single-point spraying residence time is 3 to 5 s.

[0074] In some embodiments, the sequence of multiple batches of arch injection is as follows: Figure 8As shown, a curved path is used during spraying to ensure uniform spraying between every two steel arch frames; a back-and-forth sweeping spraying method is used on the arch top to control the rebound rate.

[0075] In some embodiments, as Figure 3 As shown in S53, the dosage of accelerator for concrete spraying in different areas of the seven zones is:

[0076] The arch crown is 8-10%, the left arch shoulder is 6-8%, the left arch foot of the upper step is 3-6%, the right arch shoulder is 6-8%, the right arch foot of the upper step is 3-6%, the left arch foot of the lower step is 3-6%, and the right arch foot of the lower step is 3-6%.

[0077] In some embodiments, in S53, the concrete spraying wind pressure is controlled at 0.6-0.8 MPa; the spraying angle is controlled at 75-105°, and the wind shear force affects the concrete rebound rate as follows: Figure 4 As shown; the interval time between adjacent layers of spraying is recommended to be controlled at 10 to 15 minutes; the spraying distance is 0.8 to 1.5 meters, and the schematic diagram of the effect of spraying distance on rebound rate is shown as follows Figure 5 shown.

[0078] In some embodiments, S1 includes the following steps:

[0079] The wet spraying robot is in place;

[0080] Complete the fixing of the front and rear legs, and the connection of the external power supply, air duct, and water pipe;

[0081] Start trial operation and debugging, extend the spray arm by operating the controller, start the air compressor and set the accelerator dosage at the same time;

[0082] After the trial run is completed, the spray head is installed.

[0083] In some embodiments, S2 includes the following steps:

[0084] Before spraying concrete, use a high-pressure air gun to clean the rock surface after blasting to ensure that there is no residue on the rock surface, and avoid the sprayed concrete sticking to the residue and falling off, which will increase the concrete rebound rate and increase material consumption.

[0085] In some embodiments, S3 includes the following steps:

[0086] Before spraying concrete, use mortar of the same grade to lubricate the pipe. This not only lubricates the pipe section, but also allows the mortar to be sprayed onto the rock surface to avoid the phenomenon of gravel not being able to bond due to direct contact between concrete and rock surface.

[0087] When lubricating the pipe, the pumping displacement is controlled at 15m 3 / h, the dosage of accelerator is adjusted to 10%.

[0088] In some embodiments, shotcrete control should ensure the spraying effect while meeting good fluidity and slurry coating, and reduce the risk of pump blockage. Specifically, S4 includes the following steps:

[0089] The slump of concrete is controlled within the range of 160-180mm;

[0090] The slump loss rate of concrete over time is ≤5% (tested at 23±2℃ for 1.5h), and the waiting time for concrete transport tankers during construction is ≤90 minutes;

[0091] It is strictly forbidden to add water on site, and the residual water should be drained before the tank truck is loaded with concrete.

[0092] In some embodiments, S55 includes the following steps:

[0093] Use tunnel spray-mix scraper to install it on the spraying machine nozzle;

[0094] After each truckload of material is sprayed, use the tunnel spray-mixing scraper to clean the concrete bonded on the spandrels and arch supports;

[0095] The bonded concrete at the arch foot is cleaned manually using a manual floor shovel.

[0096] In the above-mentioned S55, during the spraying process, the concrete protruding from the I-beam needs to be scraped off to ensure that the spraying surface is flat. A tunnel spraying scraper is installed at the nozzle of the wet spraying machine. After each truckload of material is sprayed, the tunnel spraying scraper is used to clean the concrete adhering to the arch spandrels and arch frames, and the concrete adhering to the arch feet is cleaned manually using a manual floor shovel. The tunnel spraying scraper is equipped with a compression spring, which ensures that the protruding parts of the concrete are effectively scraped off and the flatness meets the requirements. At the same time, it greatly reduces the wear of the scraper on the machine and reduces the occurrence of over-scraping, which is safer and more effective than conventional scrapers.

[0097] In some embodiments, as Figure 6 As shown, the tunnel spray-mix scraper includes a sleeve 1, one end of which is symmetrically provided with a sleeve slot 2, the other end of which is fixedly provided with a compression spring 3, and the end of the compression spring 3 facing away from the sleeve 1 is fixedly provided with a scraper 4, wherein the ends of the compression spring 3 are flattened and welded to the scraper 4 and the sleeve 1 respectively; specifically, the scraper is a steel plate of 400×200×10mm, the compression spring is a spring with a wire diameter of φ12, an outer diameter of 70mm, and a height of 250mm, and the sleeve 1 is a cylinder with an inner diameter of 25cm formed by bending a 10mm thick steel plate; as shown Figure 7 As shown, the manual floor shovel has a shovel plate 5, and a rod body 6 is fixedly provided at one end of the shovel plate 5; specifically, the shovel plate 5 is an inverted trapezoidal steel plate with a thickness of 10 mm, an upper edge width of 200 mm, and a length of the rod body 6 of 3 m.

[0098] The application effect of the tunnel initial support shotcrete zoning quality control construction method in this embodiment in a certain tunnel project. The tunnel project adopts the micro-step full-section construction method, and the initial support is protected by shotcrete. The amount of shotcrete used for each meter of upper and lower steps is 8.02m 3 The original construction initial support shotcrete backfill rate was about 22%. After adopting the "tunnel initial support shotcrete zoning quality control construction method", the initial support shotcrete backfill rate per meter was reduced to 8%, that is, the amount of shotcrete used per meter was reduced from (8.02*(100%+22%))=9.78m 3 Reduced to (8.02*(100%+8%))=8.66m 3 , the amount of concrete used per meter is reduced by 1.13m 3 According to the design estimate and the bidding documents, the comprehensive unit price of shotcrete is RMB 1,197.79 / m 3 From this, we can calculate that when the "Zone Quality Control Construction Method for Initial Tunnel Support Shotcrete" is used for initial tunnel support shotcrete construction, the tunnel project can save 1,353.5 yuan per linear meter of initial support shotcrete. For this section, the entire building and inclined shaft total 57,266.7 meters, saving a total of 77.51 million yuan, with significant economic benefits. At the same time, the "Zone Quality Control Construction Method for Initial Tunnel Support Shotcrete" reduces the amount of shotcrete used and speeds up construction, thereby saving resources such as machinery electricity and labor costs on the original construction results, resulting in significant overall comprehensive economic benefits.

[0099] In summary, the zoning quality control construction method for shotcrete in the initial support of the tunnel is simple to operate. The shotcrete adopts the construction method of "seven-zone spraying, zoning control of accelerator parameters, and zoning control of spraying flow rate and volume". A wet spraying machine is used for operation, and no other equipment and materials need to be added. The operation is simple and convenient for construction personnel. The process is closely connected. Through zoning spraying, the construction of the arch crown and arch foot can be carried out in a continuous manner. After each arch crown spraying, the lower step and the lower part of the upper step can be sprayed and accumulated. The process is closely connected, which improves the construction efficiency and progress. The material dosage is dynamically adjusted. By adjusting the dosage of the accelerator for the arch crown and arch foot during shotcrete spraying, the rebound rate of the shotcrete is effectively guaranteed, the material utilization rate is improved, and the construction cost is reduced.

[0100] The zoning quality control construction method for tunnel initial support shotcrete is suitable for tunnel projects where initial support shotcrete is constructed using a concrete wet spraying robot. It has the characteristics of simple operation, short construction period, low safety risk and low construction cost.

[0101] Thus far, various embodiments of the present invention have been described in detail. To avoid obscuring the concept of the present invention, some details well known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0102] The above-described embodiments represent only some embodiments of the present invention. Although the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the appended claims.

Claims

1. A method for controlling the quality of shotcrete in the initial support of a tunnel, characterized by: The following steps are involved: S1, inspection before wet spraying robot operation; S2, rock face cleaning; S3, mortar lubrication pipe; S4, concrete index control; S5, shotcrete construction; The S5 includes the following steps: S51, the rock face arch is divided into seven areas; S52: Before starting wet spraying, pre-spray 10-20mm thick mortar with the same mix ratio from bottom to top to increase the base roughness; S53, spray according to seven zones, and control the thickness of each spraying to 50mm±5mm; S54, repeat S53 until the injection is completed; S55, surface leveling.

2. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1 is characterized by: In the step S51, the rock face arch portion is divided into seven sections: the arch crown, the left spandrel, the left arch foot of the upper step, the right spandrel, the right arch foot of the upper step, the left arch foot of the lower step, and the right arch foot of the lower step; In S53, the injection order of the seven sections is: crown, left spandrel, left arch foot of upper step, crown, right spandrel, right arch foot of upper step, crown, left spandrel, left arch foot of lower step, crown, right spandrel, right arch foot of lower step.

3. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1 is characterized by: In said S53, the dosage of the accelerating agent for concrete spraying in different areas of the seven sections is: The arch crown is 8-10%, the left arch shoulder is 6-8%, the left arch foot of the upper step is 3-6%, the right arch shoulder is 6-8%, the right arch foot of the upper step is 3-6%, the left arch foot of the lower step is 3-6%, and the right arch foot of the lower step is 3-6%.

4. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1 is characterized by: In said S53, the concrete spraying air pressure is controlled at 0.6-0.8 MPa; The spraying angle is controlled at 75-105°; the interval between spraying of adjacent layers is recommended to be controlled at 10-15 minutes; the spraying distance is 0.8-1.5m.

5. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1 is characterized in that: Said S1 comprises the following steps: The wet spraying robot is in place; Complete the fixing of the front and rear legs, and the connection of the external power supply, air duct, and water pipe; Start trial operation and debugging, extend the spray arm by operating the controller, start the air compressor and set the accelerator dosage at the same time; After the trial run is completed, the spray head is installed.

6. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1 is characterized in that: The S2 comprises the following steps: Before spraying concrete, use a high-pressure air gun to clean the rock surface after blasting.

7. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1, characterized in that: The S3 includes the following steps: Use mortar of the same grade to lubricate the pipes before spraying concrete; When lubricating the pipe, the pumping displacement is controlled at 15m 3 / h, the dosage of accelerator is adjusted to 10%.

8. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1, characterized in that: The S4 comprises the following steps: The slump of concrete is controlled within the range of 160-180mm; The slump loss rate of concrete over time is ≤5%, and the waiting interval time of concrete transport tankers during construction is ≤90 minutes.

9. The method for controlling the quality of shotcrete in the initial support of a tunnel according to claim 1, characterized in that: The S55 comprises the following steps: Use tunnel spray-mix scraper to install it on the spraying machine nozzle; After each truckload of material is sprayed, use the tunnel spray-mixing scraper to clean the concrete bonded on the spandrels and arch supports; The bonded concrete at the arch foot is cleaned manually using a manual floor shovel.

10. The method for controlling the quality of shotcrete in different zones for initial support of a tunnel according to claim 9, characterized in that: The tunnel spray-mixing scraper includes a sleeve, one end of which is symmetrically provided with a sleeve slot, the other end of which is fixedly provided with a compression spring, and the end of the compression spring which is away from the sleeve is fixedly provided with a scraper; The manual floor shovel has a shovel plate, and one end of the shovel plate is fixedly provided with a rod body.

Images