CN114294021A - Construction method for preliminary support of underground excavation channel - Google Patents
Construction method for preliminary support of underground excavation channel Download PDFInfo
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- CN114294021A CN114294021A CN202111669269.5A CN202111669269A CN114294021A CN 114294021 A CN114294021 A CN 114294021A CN 202111669269 A CN202111669269 A CN 202111669269A CN 114294021 A CN114294021 A CN 114294021A
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Abstract
The application discloses a construction method of a primary support of an underground excavation channel, which is characterized in that a first concrete layer with a first design thickness is formed by primarily spraying concrete on an operation surface by a wet spraying method so as to primarily fix the operation surface; then, installing a grid steel frame on the first concrete layer, and spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness so as to further reinforce the supporting structure of the working face; finally, embedding a grouting pipe in the second concrete layer, and injecting grout into the grouting pipe to form the primary support of the underground excavation channel; and (3) constructing primary support with enough strength through three-level reinforcement so as to ensure the safety in the construction process of the underground excavation channel.
Description
Technical Field
The application relates to the technical field of underground excavation construction, in particular to a construction method for primary support of an underground excavation channel.
Background
The underground excavation method is that the ground is not excavated and the underground excavation mode is adopted for construction. When the buried depth exceeds a certain limit, the open-cut method is not suitable, but the underground-cut method is used. Although the construction technology of urban tunnels and underground engineering by the shallow-buried underground excavation method is mature, due to the uncertainty of engineering hydrogeological conditions and the complexity of construction environments, a plurality of construction risks still exist in the construction process of underground engineering by the shallow-buried underground excavation method, and a plurality of risk accidents also occur.
Primary support is a safe construction protection measure in underground excavation construction. After the tunnel is excavated, in order to control the stress of surrounding rocks to be properly released and deformed, the structural safety degree is increased, the construction is convenient, and a structural layer which has smaller rigidity and is used as a part of a permanent bearing structure is immediately constructed after the tunnel is excavated. During underground excavation construction, the surrounding rock support is generally divided into primary support and secondary lining, and the secondary lining is generally a concrete or reinforced concrete structure. The form of bracing immediately after excavation, prior to secondary lining construction, is referred to as primary bracing. However, how to construct primary supports meeting the construction strength requirement becomes a very important safety environment for the construction of the underground excavation channel.
Disclosure of Invention
The present application is proposed to solve the above-mentioned technical problems. The embodiment of the application provides a construction method of an underground excavation channel primary support, and solves the problem of how to construct the primary support meeting the strength requirement in the construction process of the underground excavation channel.
The application provides a construction method for primary support of an underground excavation channel, which comprises the following steps: primarily spraying concrete on a working surface by adopting a wet spraying method to form a first concrete layer with a first design thickness; installing a grid steel frame on the first concrete layer; the grid steel frame comprises a plurality of spliced grids, and the distance between every two adjacent grids is 0.5 m; spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness; embedding a grouting pipe in the second concrete layer; the soil entering end of the grouting pipe is wrapped by plastic, and the length of the grouting pipe reserved outside the second concrete layer is 0.1 m; and injecting grout into the grouting pipe to form the primary support of the undercut channel.
In one embodiment, the primary spraying of concrete on the working surface by the wet spraying method comprises the following steps: sending a mixture containing cement, sand and an accelerating agent into a spraying machine, and sending the mixture to a spray head through a pressure fan; and delivering water on the spray head for three times, and spraying the mixture and the water onto the working surface.
In one embodiment, the spraying concrete on the grid steel frame comprises: and spraying concrete between the grid steel frame and the first concrete layer, and then spraying concrete between the adjacent grids.
In one embodiment, said mounting grid steel frame on said first concrete layer comprises: splicing a plurality of grills on the first concrete layer, and hanging a first reinforcing mesh on the inner side of the grille steel frame; and fixedly connecting the plurality of trusses of grids.
In one embodiment, said hanging the first reinforcing mesh inside the grid steel frame includes: in the latticeThe inner side of the grid steel frame is hung
The first reinforcing mesh is arranged adjacent to the first reinforcing mesh in an overlapped mode, and the overlapped length is 0.15 m.
In an embodiment, the fixedly connecting the multiple trussed grilles comprises: by using
And the steel pull rod and the bolt are simultaneously connected with the adjacent grids.
In an embodiment, said installing grid steel frames on said first concrete layer after said fixedly connecting said plurality of grids further comprises: and inserting a square wood block between the first concrete layer and the grid steel frame so as to wedge the first concrete layer and the grid steel frame.
In an embodiment, said installing grid steel frame on said first concrete layer further comprises, after said inserting wood tiles between said first concrete layer and said grid steel frame: and laying a second reinforcing mesh outside the grid steel frame, and binding and fixing the grid steel frame and the second reinforcing mesh.
In an embodiment, said pre-embedding the slip casting pipe in the second concrete layer includes: every horizontal cross section on second concrete layer is pre-buried 3 slip casting pipes, just the longitudinal separation distance of slip casting pipe is 3 meters, the slip casting pipe with the perpendicular line contained angle on second concrete layer is less than 3 degrees.
In one embodiment, the injecting the slurry into the slurry injecting pipe comprises: injecting mixed grout of cement paste and water glass into the grouting pipe; wherein the grouting pressure is less than 0.2 MPa, and the grouting speed is less than 50L/min.
According to the construction method of the primary support of the underground excavation channel, a first concrete layer with the first design thickness is formed by primarily spraying concrete on an operation surface by a wet spraying method, so that the operation surface is primarily fixed; then, installing a grid steel frame on the first concrete layer, and spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness so as to further reinforce the supporting structure of the working face; finally, embedding a grouting pipe in the second concrete layer, and injecting grout into the grouting pipe to form the primary support of the underground excavation channel; and (3) constructing primary support with enough strength through three-level reinforcement so as to ensure the safety in the construction process of the underground excavation channel.
Drawings
The above and other objects, features and advantages of the present application will become more apparent by describing in more detail embodiments of the present application with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings, like reference numbers generally represent like parts or steps.
Fig. 1 is a schematic flow chart of a construction method of an underground excavation channel primary support according to an exemplary embodiment of the present application.
Fig. 2 is a schematic flow chart of an installation method of a grid steel frame according to an exemplary embodiment of the present application.
Fig. 3 is a schematic structural view of construction equipment for preliminary support of an underground excavation channel according to an exemplary embodiment of the present application.
Fig. 4 is a schematic structural view of construction equipment for preliminary support of an underground excavation channel according to another exemplary embodiment of the present application.
Fig. 5 is a block diagram of an electronic device provided in an exemplary embodiment of the present application.
Detailed Description
Hereinafter, example embodiments according to the present application will be described in detail with reference to the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present application and not all embodiments of the present application, and that the present application is not limited by the example embodiments described herein.
Fig. 1 is a schematic flow chart of a construction method of an underground excavation channel primary support according to an exemplary embodiment of the present application. As shown in fig. 1, the construction method of the preliminary support of the underground excavation channel comprises the following steps:
step 100: the method comprises the steps of spraying concrete on a working surface for the first time by a wet spraying method to form a first concrete layer with a first design thickness.
In an embodiment, the specific implementation manner of step 100 may be: the method comprises the steps of feeding a mixture containing cement, gravel and an accelerating agent into a sprayer, conveying the mixture to a spray head through a blower, conveying water on the spray head for three times, and spraying the mixture and the water onto a working surface to form a first concrete layer with a first design thickness.
The primary concrete spraying is to reduce dust emission, and adopts a 'wet spraying method' process: the cement, the sand and the setting accelerator are fed according to the proportion requirement, the mixture is evenly mixed on the ground through a stirrer and then is conveyed to the working surface, the mixture is conveyed into a sprayer and is conveyed to a spray head through a blower, water is conveyed to the spray head for three times, and the spraying is sequentially carried out from bottom to top.
The slump of the wet sprayed concrete is generally 10-13 cm, the water-cement ratio is 0.45, the sand rate is 56%, the water-cement ratio is 0.45, and an accelerator with the cement amount being 5% is doped. The raw material cement is ordinary portland cement; the fine aggregate adopts medium sand, the fineness modulus is more than 2.5, and the water content is controlled between 5% and 7%; pebbles are adopted as coarse aggregates, and the particle size is less than 10 mm; the mixing water is drinking water. The sprayed material must be sieved before stirring, and the mixture can be used with stirring, and the storage time is not more than 20 min. After the quick-setting admixture is doped, the initial setting time of the concrete is about 3 minutes, and the final setting time is controlled to be about 10 minutes.
Before the concrete is sprayed, a stirrer is installed and debugged on the ground, whether a conveying pipe is sealed and airtight is checked, a feeding pipe and a high-pressure air pipe are arranged, and the mixture is guaranteed to be smooth and unimpeded in the spraying process; cleaning the sprayed surface and embedding the mark for controlling the spraying thickness.
Step 200: installing a grid steel frame on the first concrete layer; the grid steel frame comprises a plurality of spliced grids, and the distance between every two adjacent grids is 0.5 m.
And after the grid steel frame is manufactured by adopting the sectional cold bending, transporting the grid steel frame to a field for installation. The grid steel frame has accurate processing size and smooth arc. The steel bar welding of grid steel frame satisfies the standard requirement, and the steelframe bilateral symmetry of grid steel frame carries out weld forming, and steelframe owner muscle center and axis coincide.
The processing shape and size of the grid steel frame must meet the design requirements, the surface of the steel bar should be clean and free of damage, oil stain, rust and the like, and the steel bar with granular or flaky old rust cannot be used. The steel bars should be straight and have no local tortuosity.
The following regulations should be met when cutting the steel bars: when in operation, the clearance adjustment of the cutter blade is carried out, and whether the cutter edge is sharp or not is checked, and the neck or the elbow of the reinforcing steel bar must be cut off. The cut steel bars are orderly stacked according to the batch, grade, specification and model so as to be convenient for searching.
The hooking or bending of the reinforcing bars should comply with the following regulations: the I-grade steel bar needs to be hooked at 180 degrees, the bending diameter (d) of the arc of the I-grade steel bar is not less than 2.5 times of the diameter (d) of the steel bar, and the length of the straight part is not less than 3 times of the diameter (d) of the steel bar; when the tail end of the III-grade steel bar needs to be bent at 90 degrees or 135 degrees, the bending diameter (d) of the III-grade steel bar is not suitable to be less than 4 times of the diameter (d) of the steel bar; the bending diameter (d) of the bending part at the middle part of the bent steel bar is not less than 5 times of the diameter (d) of the steel bar; the tail end of a stirrup made of I-grade steel bars is used as a hook, the bending diameter of the hook is larger than the diameter of the stressed steel bar and is not smaller than 2.5 times of the diameter of the stirrup, and the straight part of the hook is not smaller than 10 times of the diameter of the stirrup; the form of the hook should be in accordance with design or specifications.
The assembly and the positioning of the steel bar before construction meet the following requirements: when lap welding is adopted, the lap axes of the two main ribs are ensured to be parallel (not pre-bent). And when the multilayer is subjected to spin welding, the good fusion of the initial end and the terminal end of the first layer of welding line is ensured. When the steel bar joint adopts lap welding, the length of the welding seam is not less than the lap length, and the height h of the welding seam is not less than 0.3d and not less than 4 mm. The width b of the welding seam is more than or equal to 0.7d and not less than 10 mm, when the steel plate and the steel bar joint are in lap welding, the height h of the welding seam is more than or equal to 0.35d and not less than 6 mm, and the width b of the welding seam is more than or equal to 0.5d and not less than 8 mm.
Step 300: and spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness.
In an embodiment, the specific implementation manner of step 300 may be: concrete is sprayed between the grid steel frame and the first concrete layer, and then concrete is sprayed between adjacent grids.
The air supply pressure is strictly controlled in the injection process, and the working air pressure of the injection machine is controlled to be 0.3 MPa to 0.5 MPa. The spray nozzle is vertical to the operation surface, the distance between the spray nozzle and the sprayed surface is within 1.0-1.5 m, the spray angle is preferably kept vertical to the sprayed surface, and if the sprayed surface is covered by a steel mesh and a grid, the spray nozzle can slightly deflect 100-200 mm; the spraying sequence is from bottom to top, the material beam moves in a rotating track, a circle is pressed into a half circle, and the material beam is longitudinally shaped like a snake; the sprayed concrete is sprayed in layers, and the thickness of one-time spraying is generally 7-10 cm.
And after the concrete spraying is finished each time, immediately checking the thickness, and if the thickness is not enough, performing additional spraying to reach the designed thickness. The sprayed concrete is compact and flat, has no cracks, falls off, leaks, sprays, ribs, hollows, water leakage and the like, the allowable deviation of the surface flatness is controlled to be 15 mm, and the vector-chord ratio is not more than 1/6. And curing the sprayed concrete for 2 hours, wherein the curing time is not less than 14 hours. Two groups of spraying mixing compressive strength test pieces are taken per 20 m side wall.
Step 400: embedding a grouting pipe in the second concrete layer; wherein, the end of penetrating into soil of slip casting pipe adopts plastics parcel, and the length that slip casting pipe reserves outside the second concrete layer is 0.1 meter.
In one embodiment, pre-embedding the slip casting pipe in the second concrete layer includes: 3 grouting pipes are embedded in each transverse section of the second concrete layer, the longitudinal distance between the grouting pipes is 3 meters, and the included angle between each grouting pipe and the vertical line of the second concrete layer is smaller than 3 degrees.
Grouting pipe adoption
And (3) generally welding a steel pipe, embedding the steel pipe in the concrete during primary support and concrete spraying, wrapping the soil-entering end with plastic, and exposing the outer end of the steel pipe to the surface of the support by 10 cm. The distance between grouting holes at the back of the primary support is 3 meters, and the circumferential construction joints are avoided during hole distribution.
Step 500: and injecting grout into the grouting pipe to form primary support of the undercut channel.
In an embodiment, the specific implementation manner of step 500 may be: injecting mixed slurry of cement slurry and water glass into the grouting pipe; wherein the grouting pressure is less than 0.2 MPa, and the grouting speed is less than 50L/min.
The grouting depth is 0.6 m behind the primary support, the grouting pressure is less than 0.2 MPa, the filling final pressure is 0.5 MPa, the slurry diffusion radius is 1.4-1.8 m, the grouting speed is not more than 50 liters/minute, and the method is used for consolidating the arch-back loose rock-soil body and filling the gaps possibly existing so as to reduce stratum loosening and ground surface settlement to the maximum extent.
The slurry has the characteristics of strong fluidity, strong permeability, quick setting and the like: cement paste and water glass; wherein, the cement paste adopts ordinary Portland P.O42.5 cement, the mixing proportion is that water and cement are 1: 1; the water glass has the concentration of 42Be', and the mixing ratio of water to water glass is 1: 1.
During grouting, cement paste and water glass are selected according to the field condition, and the matching ratio of the concrete water glass and the cement paste in the cement paste and the grouting pressure can be determined according to the soil body reinforcing effect and the geological condition. For example, the ratio of the liquid A to the liquid B is 1:1, and an accelerator is added according to the grouting condition. The gel time for preparing the double-liquid slurry is 30-90 seconds.
According to the construction method of the primary support of the underground excavation channel, a first concrete layer with the first design thickness is formed by primarily spraying concrete on an operation surface by a wet spraying method, so that the operation surface is primarily fixed; then, installing a grid steel frame on the first concrete layer, and spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness so as to further reinforce the supporting structure of the working face; finally, embedding a grouting pipe in the second concrete layer, and injecting grout into the grouting pipe to form the primary support of the underground excavation channel; and (3) constructing primary support with enough strength through three-level reinforcement so as to ensure the safety in the construction process of the underground excavation channel.
Fig. 2 is a schematic flow chart of an installation method of a grid steel frame according to an exemplary embodiment of the present application. As shown in fig. 2, the step 200 may include:
step 210: and splicing a plurality of grilles on the first concrete layer, and hanging a first reinforcing mesh on the inner side of the grille steel frame.
The method mainly comprises measurement control and assembly control in the installation process of the grid reinforcing steel bars, wherein after one cycle of earth excavation is completed, an excavated surface is processed, and after the excavation clearance meets the requirement, the grid is assembled and erected. And trial splicing is carried out on the grid steel frames in a grid processing factory, whether the distortion phenomenon exists or not is checked, and the qualified grid steel frames are transported to a construction site. Before the grid steel frame is installed, the deficient slag and other impurities under the arch foot should be removed, and the over-digging parts are filled with concrete blocks respectively. And processing the grating outside the hole into roof trusses, and installing the grating in the hole after trial assembly without errors. The unevenness and the deflection of each grid are less than or equal to 10 mm. When the underground excavation channel is installed in a hole, the grids on each circulating full section of the underground excavation channel are erected in the same plane, and the step distance difference is less than or equal to 10 mm.
In an embodiment, the specific implementation manner of step 210 may be: the inner side of the grid steel frame is hung
The first reinforcing mesh is overlapped with the adjacent first reinforcing mesh, and the overlapping length is 0.15 m. And (4) processing the reinforcing mesh into a reinforcing mesh sheet in advance, and transporting the reinforcing mesh sheet to the operation surface for installation. The reinforcing mesh should be firmly bound with the main bars of the grid steel frame, so that the phenomenon that the plate is not firmly bound and falls off in the spraying process is prevented, and the concrete protective layer of the reinforcing mesh is not less than 20 mm.
Step 220: and fixedly connecting a plurality of grills.
Specifically, adopt
The steel pull rods and the bolts are simultaneously connected with the adjacent grids.
By using
And (II) steel pull rods are arranged inside and outside in a staggered manner to carry out lap welding construction, the circumferential intervals of the steel pull rods are 1 meter, and the longitudinal length of the steel pull rods is 1 meter. And the steel pull rod lap welding meets the construction requirements of single-side welding for 10d and double-side welding for 5 d.
The grid steel frames are assembled on the excavation working surface, and the trusses of grids are connected through bolts. Rely on four bolts to pass the bolt hole connection of reserving on the connecting plate, four bolts all adjust the back of detaining well, carry out the headroom inspection, and the adjustment satisfies just can tighten up the bolt in proper order. The connecting plate position is the weak position of grid steelframe atress, if cause connecting plate connecting bolt to screw up because of special circumstances, should increase the group at connecting plate position and weld the muscle, and the homonymy connecting plate position all needs to increase group and welds the muscle.
In an embodiment, as shown in fig. 2, after step 220, step 200 may further include:
step 230: and inserting a square wood block between the first concrete layer and the grid steel frame so as to wedge the first concrete layer and the grid steel frame.
The grid steel frame and the soil layer are wedged tightly by square wood blocks, the excavation size is adjusted, and then the grid steel frame and the soil layer are densely sprayed by spraying concrete so as to improve the fixing strength between the grid steel frame and the soil layer.
In an embodiment, as shown in fig. 2, after the step 230 is not performed, the step 200 may further include:
step 240: and laying a second steel bar mesh outside the grid steel frame, and binding and fixing the grid steel frame and the second steel bar mesh.
And reinforcing meshes are paved on the inner side and the outer side of the grid steel frame so as to further enhance the fixing effect on the grid steel frame.
In addition, a space between the back of the primary support and the soil body is 1:1, filling cement mortar or cement paste to ensure the close adhesion of the back of the primary support and surrounding rocks. And pure cement slurry with 0.2 MPa is filled between the primary support and the secondary lining, and the close adhesion between the primary support and the secondary lining is ensured. And backfilling and grouting between the primary support and the secondary lining are carried out when the strength of the secondary lining concrete reaches over 75 percent of the design strength, and the grouting pressure is not more than 0.2 MPa.
Fig. 3 is a schematic structural view of construction equipment for preliminary support of an underground excavation channel according to an exemplary embodiment of the present application. As shown in fig. 3, the construction equipment 30 for preliminary bracing includes: a first spraying module 31 for primarily spraying concrete on the working surface by a wet spraying method to form a first concrete layer of a first design thickness; a grid mounting module 32 for mounting a grid steel frame on the first concrete layer; the grid steel frame comprises a plurality of spliced grids, and the distance between every two adjacent grids is 0.5 m; the second spraying module 33 is used for spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness; the pre-embedding module 34 is used for pre-embedding the grouting pipe in the second concrete layer; wherein the soil entering end of the grouting pipe is wrapped by plastic, and the length of the grouting pipe reserved outside the second concrete layer is 0.1 meter; and the grouting module 35 is used for injecting grout into the grouting pipe to form primary support of the underground excavation channel.
According to the construction equipment for the primary support of the underground excavation channel, a first concrete layer with a first design thickness is formed by primary concrete spraying on an operation surface through a first spraying module 31 by adopting a wet spraying method, so that the operation surface is primarily fixed; then, the grid steel frame is installed on the first concrete layer through the grid installation module 32, and concrete is sprayed on the grid steel frame through the second spraying module 33 to form a second concrete layer with a second design thickness so as to further reinforce the supporting structure of the working face; finally, the pre-embedding module 34 pre-embeds the grouting pipe in the second concrete layer, and the grouting module 35 injects grout into the grouting pipe to form primary support of the underground excavation channel; and (3) constructing primary support with enough strength through three-level reinforcement so as to ensure the safety in the construction process of the underground excavation channel.
In an embodiment, the first injection module 31 may be further configured to: the method comprises the steps of feeding a mixture containing cement, gravel and an accelerating agent into a sprayer, conveying the mixture to a spray head through a blower, conveying water on the spray head for three times, and spraying the mixture and the water onto a working surface to form a first concrete layer with a first design thickness.
The slump of the wet sprayed concrete is generally 10-13 cm, the water-cement ratio is 0.45, the sand rate is 56%, the water-cement ratio is 0.45, and an accelerator with the cement amount being 5% is doped. The raw material cement is ordinary portland cement; the fine aggregate adopts medium sand, the fineness modulus is more than 2.5, and the water content is controlled between 5% and 7%; pebbles are adopted as coarse aggregates, and the particle size is less than 10 mm; the mixing water is drinking water. The sprayed material must be sieved before stirring, and the mixture can be used with stirring, and the storage time is not more than 20 min. After the quick-setting admixture is doped, the initial setting time of the concrete is about 3 minutes, and the final setting time is controlled to be about 10 minutes.
In an embodiment, the second injection module 33 may be further configured to: concrete is sprayed between the grid steel frame and the first concrete layer, and then concrete is sprayed between adjacent grids.
The air supply pressure is strictly controlled in the injection process, and the working air pressure of the injection machine is controlled to be 0.3 MPa to 0.5 MPa. The spray nozzle is vertical to the operation surface, the distance between the spray nozzle and the sprayed surface is within 1.0-1.5 m, the spray angle is preferably kept vertical to the sprayed surface, and if the sprayed surface is covered by a steel mesh and a grid, the spray nozzle can slightly deflect 100-200 mm; the spraying sequence is from bottom to top, the material beam moves in a rotating track, a circle is pressed into a half circle, and the material beam is longitudinally shaped like a snake; the sprayed concrete is sprayed in layers, and the thickness of one-time spraying is generally 7-10 cm.
And after the concrete spraying is finished each time, immediately checking the thickness, and if the thickness is not enough, performing additional spraying to reach the designed thickness. The sprayed concrete is compact and flat, has no cracks, falls off, leaks, sprays, ribs, hollows, water leakage and the like, the allowable deviation of the surface flatness is controlled to be 15 mm, and the vector-chord ratio is not more than 1/6. And curing the sprayed concrete for 2 hours, wherein the curing time is not less than 14 hours. Two groups of spraying mixing compressive strength test pieces are taken per 20 m side wall.
In an embodiment, the pre-embedded module 34 may be further configured to: 3 grouting pipes are embedded in each transverse section of the second concrete layer, the longitudinal distance between the grouting pipes is 3 meters, and the included angle between each grouting pipe and the vertical line of the second concrete layer is smaller than 3 degrees.
Grouting pipe adoption
And (3) generally welding a steel pipe, embedding the steel pipe in the concrete during primary support and concrete spraying, wrapping the soil-entering end with plastic, and exposing the outer end of the steel pipe to the surface of the support by 10 cm. The distance between grouting holes at the back of the primary support is 3 meters, and the circumferential construction joints are avoided during hole distribution.
In an embodiment, the grouting module 35 may be further configured to: injecting mixed slurry of cement slurry and water glass into the grouting pipe; wherein the grouting pressure is less than 0.2 MPa, and the grouting speed is less than 50L/min.
The grouting depth is 0.6 m behind the primary support, the grouting pressure is less than 0.2 MPa, the filling final pressure is 0.5 MPa, the slurry diffusion radius is 1.4-1.8 m, the grouting speed is not more than 50 liters/minute, and the method is used for consolidating the arch-back loose rock-soil body and filling the gaps possibly existing so as to reduce stratum loosening and ground surface settlement to the maximum extent.
Fig. 4 is a schematic structural view of construction equipment for preliminary support of an underground excavation channel according to another exemplary embodiment of the present application. As shown in fig. 4, the grill mounting module 32 may include: the splicing unit 321 is used for splicing a plurality of grills on the first concrete layer, and meanwhile, a first reinforcing mesh is hung on the inner side of the grille steel frame; and a fixing unit 322 for fixedly connecting the plurality of grills.
In an embodiment, the splicing unit 321 may be further configured to: the inner side of the grid steel frame is hung
The first reinforcing mesh is overlapped with the adjacent first reinforcing mesh, and the overlapping length is 0.15 m.
In an embodiment, the fixing unit 322 may be further configured to: by using
The steel pull rods and the bolts are simultaneously connected with the adjacent grids.
By using
And (II) steel pull rods are arranged inside and outside in a staggered manner to carry out lap welding construction, the circumferential intervals of the steel pull rods are 1 meter, and the longitudinal length of the steel pull rods is 1 meter. And the steel pull rod lap welding meets the construction requirements of single-side welding for 10d and double-side welding for 5 d.
In one embodiment, as shown in fig. 4, the grid mounting module 32 may further include: and the wedging unit 323 is used for inserting the square wood blocks between the first concrete layer and the grid steel frame so as to wedge the first concrete layer and the grid steel frame.
In one embodiment, as shown in fig. 4, the grid mounting module 32 may further include: and a steel frame laying unit 324 for laying a second steel bar mesh outside the grid steel frame and binding and fixing the grid steel frame and the second steel bar mesh.
Next, an electronic apparatus according to an embodiment of the present application is described with reference to fig. 5. The electronic device may be either or both of the first device and the second device, or a stand-alone device separate from them, which stand-alone device may communicate with the first device and the second device to receive the acquired input signals therefrom.
FIG. 5 illustrates a block diagram of an electronic device in accordance with an embodiment of the present application.
As shown in fig. 5, the electronic device 10 includes one or more processors 11 and memory 12.
The processor 11 may be a Central Processing Unit (CPU) or other form of processing unit having data processing capabilities and/or instruction execution capabilities, and may control other components in the electronic device 10 to perform desired functions.
Memory 12 may include one or more computer program products that may include various forms of computer-readable storage media, such as volatile memory and/or non-volatile memory. The volatile memory may include, for example, Random Access Memory (RAM), cache memory (cache), and/or the like. The non-volatile memory may include, for example, Read Only Memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer readable storage medium and executed by the processor 11 to implement the method of construction of an undermined access preliminary support of the various embodiments of the present application described above and/or other desired functions. Various contents such as an input signal, a signal component, a noise component, etc. may also be stored in the computer-readable storage medium.
In one example, the electronic device 10 may further include: an input device 13 and an output device 14, which are interconnected by a bus system and/or other form of connection mechanism (not shown).
When the electronic device is a stand-alone device, the input means 13 may be a communication network connector for receiving the acquired input signals from the first device and the second device.
The input device 13 may also include, for example, a keyboard, a mouse, and the like.
The output device 14 may output various information including the determined distance information, direction information, and the like to the outside. The output devices 14 may include, for example, a display, speakers, a printer, and a communication network and its connected remote output devices, among others.
Of course, for simplicity, only some of the components of the electronic device 10 relevant to the present application are shown in fig. 5, and components such as buses, input/output interfaces, and the like are omitted. In addition, the electronic device 10 may include any other suitable components depending on the particular application.
The computer program product may be written with program code for performing the operations of embodiments of the present application in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server.
The computer-readable storage medium may take any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may include, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit embodiments of the application to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof.
Claims (10)
1. A construction method for primary support of an underground excavation channel is characterized by comprising the following steps:
primarily spraying concrete on a working surface by adopting a wet spraying method to form a first concrete layer with a first design thickness;
installing a grid steel frame on the first concrete layer; the grid steel frame comprises a plurality of spliced grids, and the distance between every two adjacent grids is 0.5 m;
spraying concrete on the grid steel frame to form a second concrete layer with a second design thickness;
embedding a grouting pipe in the second concrete layer; the soil entering end of the grouting pipe is wrapped by plastic, and the length of the grouting pipe reserved outside the second concrete layer is 0.1 m; and
and injecting grout into the grouting pipe to form primary support of the undercut channel.
2. The construction method of the preliminary support of the underground excavated passageway according to claim 1, wherein the primary shotcrete on the working surface by the wet blasting method includes:
sending a mixture containing cement, sand and an accelerating agent into a spraying machine, and sending the mixture to a spray head through a pressure fan; and
and (3) delivering water on the spray head for three times, and spraying the mixed material and the water onto the working surface.
3. The method of claim 1, wherein the spraying concrete on the grid steel frame comprises:
and spraying concrete between the grid steel frame and the first concrete layer, and then spraying concrete between the adjacent grids.
4. The construction method for the preliminary support of the underground excavated passageway according to claim 1, wherein the installing of the grid steel frame on the first concrete layer includes:
splicing a plurality of grills on the first concrete layer, and hanging a first reinforcing mesh on the inner side of the grille steel frame; and
and fixedly connecting the plurality of grills.
5. The construction method for the preliminary support of the underground excavation channel of claim 4, wherein the hanging of the first reinforcing mesh on the inner side of the grid steel frame comprises:
the inner side of the grid steel frame is hung
The first reinforcing mesh is arranged adjacent to the first reinforcing mesh in an overlapped mode, and the overlapped length is 0.15 m.
6. The construction method of an underground excavation channel preliminary support according to claim 4, wherein the fixedly connecting the plurality of grills includes:
by using
And the steel pull rod and the bolt are simultaneously connected with the adjacent grids.
7. The construction method for preliminary support of a excavated channel according to claim 4, wherein the installing of the grid steel frame on the first concrete layer after the fixedly connecting of the plurality of grids further comprises:
and inserting a square wood block between the first concrete layer and the grid steel frame so as to wedge the first concrete layer and the grid steel frame.
8. The construction method of the preliminary support of the excavated channel according to claim 7, wherein the installing of the grid steel frame on the first concrete layer after the inserting of the square block between the first concrete layer and the grid steel frame further comprises:
and laying a second reinforcing mesh outside the grid steel frame, and binding and fixing the grid steel frame and the second reinforcing mesh.
9. The construction method of the preliminary support of the underground excavation channel as claimed in claim 1, wherein the embedding of the grouting pipe in the second concrete layer comprises:
every horizontal cross section on second concrete layer is pre-buried 3 slip casting pipes, just the longitudinal separation distance of slip casting pipe is 3 meters, the slip casting pipe with the perpendicular line contained angle on second concrete layer is less than 3 degrees.
10. The method of claim 1, wherein the injecting grout into the grout pipe comprises:
injecting mixed grout of cement paste and water glass into the grouting pipe; wherein the grouting pressure is less than 0.2 MPa, and the grouting speed is less than 50L/min.
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Application publication date: 20220408 |