Backfilling construction method for narrow space of gravity type wharf

Abstract

The invention relates to the technical field of wharf construction, and provides a gravity type wharf narrow space backfill construction method aiming at the situation that traditional wharf narrow area backfill construction is difficult, the gravity type wharf narrow space backfill construction method comprises the following steps that S1, a self-compacting backfill material is prepared, specifically, continuous graded broken stone is selected, a concrete curing agent and a reinforcing agent are mixed, and the self-compacting backfill material is prepared; adding water and stirring to form a self-compacting backfill material; s2, self-compacting backfill materials are backfilled in a layered mode, specifically, the self-compacting backfill materials are continuously poured to the backfill area according to the design thickness to form a backfill layer; s3, geogrid laying, wherein geogrids are laid on the top of the backfill layer; s4, the steps S2 to S3 are repeated until the backfill layer is constructed to the designed elevation of the backfill area; s5, compactness monitoring, wherein the uniformity of the backfill area is subjected to nondestructive testing through a geological radar; and S6, settlement monitoring, wherein observation points are arranged on the top face of the backfill structure, and the settlement amount of the backfill area is observed regularly. The method has the effect of facilitating backfill construction of the narrow area of the wharf.

Description

Technical Field

[0001] This application relates to the technical field of wharf construction, and in particular to a method for backfilling confined spaces in gravity-type wharves. Background Technology

[0002] In the construction and renovation of gravity-type wharves, backfilling is a key construction step to ensure the structural stability and load-bearing capacity of the wharf.

[0003] Currently, gravity wharf backfilling construction mostly adopts graded crushed stone aggregate backfilling, supplemented by mechanical compaction or manual tamping construction techniques.

[0004] In actual construction, some backfill areas are limited by spatial constraints such as the gap size and height restrictions between the wharf retaining wall and adjacent structures, making it impossible for large road rollers and compactors to enter the work area, and small compaction equipment also cannot achieve full coverage. Manual compaction is inefficient and uneven in compaction strength, which can easily lead to insufficient compaction of the backfill and excessive settlement in the later stages. Therefore, there is room for improvement. Summary of the Invention

[0005] To facilitate backfilling construction in the confined space of a wharf while ensuring the compactness of the backfill area, this application provides a gravity-based backfilling construction method for confined wharf spaces.

[0006] This application provides a method for backfilling confined spaces in a gravity-type wharf, employing the following technical solution: A method for backfilling confined spaces in a gravity-type wharf includes the following steps: S1: Preparation of self-compacting backfill: Select continuously graded crushed stone, add concrete curing agent and reinforcing agent, add water and stir to form self-compacting backfill with self-compacting fluidity; S2: Layered backfill self-compacting backfill material: The self-compacting backfill material is poured into the backfill area according to the design thickness of the backfill layer to form a backfill layer; the self-compacting backfill material is used to form preliminary compaction by its own weight and fluidity; S3: Geogrid installation: Lay geogrid on top of the backfill layer, ensuring that the width of the geogrid matches the width of the backfill layer; S4: Repeat steps S2 to S3 until the backfill layer is applied to the design elevation of the backfill area; S5: Compaction monitoring: Ground-penetrating radar is used to non-destructively test the uniformity of the backfill area, and random core samples are taken. S6: Settlement monitoring: Set up observation points on the top surface of the backfill structure and regularly monitor the settlement of the backfill area.

[0007] By adopting the above technical solution and preparing self-compacting backfill material with self-compacting fluidity, the self-compacting backfill material subsequently backfilled into the backfill area can flow freely under its own weight in the confined space and uniformly fill the voids in the backfill area. It can achieve preliminary compaction without additional compaction work, ensuring the overall compaction of the backfill area of ​​the wharf while limiting the settlement of the subsequent backfill area. This significantly improves the construction efficiency of backfilling in the confined area of ​​the wharf and reduces the overall construction difficulty. By laying geogrid on the backfill layer, the geogrid can constrain the lateral deformation of the backfill layer, which helps to enhance the integrity and shear resistance of the backfill body in the backfill area and avoid interlayer slippage caused by layered backfilling.

[0008] Preferably, in step S2, when backfilling with self-compacting backfill material, the self-compacting backfill material is poured from the edge of the backfill area toward the center of the backfill area.

[0009] By adopting the above technical solution, the self-compacting backfill material can be fully filled to the edges and corners of the backfill area, reducing the problem of uneven compaction caused by local accumulation, which is conducive to improving the overall compaction of the backfill layer.

[0010] Preferably, in step S2, before the self-compacting backfill material is backfilled and poured, several grouting pipes are vertically supported in the backfill area, and several grouting holes are arranged around the outer periphery of the grouting pipes. After the backfill layer has been initially compacted, cement grout is injected into the backfill layer through the grouting pipe to fill the internal pores of the backfill layer and achieve secondary compaction of the backfill layer.

[0011] By adopting the above technical solution, the cement grout injected into the backfill layer through the grouting pipe can diffuse into the interior of the backfill layer to further fill the tiny pores inside the backfill layer and form a strong bonded whole with the backfill layer, thereby achieving secondary compaction of the backfill layer, greatly improving the density and structural strength of the backfill body, enhancing the tightness of the bond between the backfill body and the surrounding structure, and reducing the risk of settlement in the later stage.

[0012] Preferably, in step S2, before grouting into the backfill layer through the grouting pipe, compressed air is supplied into the grouting pipe to disperse the grouting holes.

[0013] By adopting the above technical solution, compressed air can be supplied into the grouting pipe to quickly remove material residue blocking the grouting hole, ensuring that the grouting hole of the grouting pipe remains unobstructed. This facilitates the smooth discharge of cement slurry injected into the grouting pipe from the grouting hole and its even diffusion to various gaps in the backfill layer, ensuring the effect of secondary compaction.

[0014] Preferably, in step S2, when pre-embedding the grouting pipe, a filter screen is wrapped around the outer periphery of the grouting pipe, and the filter screen covers the grouting holes around the outer periphery of the grouting pipe.

[0015] By adopting the above technical solution, the filter screen is used to intercept impurities such as crushed stone particles in the subsequently poured self-compacting backfill, limiting the entry of crushed stone particles into the grouting hole and preventing blockage, thus reducing the occurrence of blockage in the grouting pipe hole.

[0016] Preferably, in step S2, when pre-embedding the grouting pipe, a support frame is welded around the grouting pipe, and the end of the support frame away from the grouting pipe is fixed to the side wall of the backfill area.

[0017] By adopting the above technical solution, the grouting pipe is stably supported in the backfill area using a support frame, which effectively resists the flow impact force generated during the subsequent self-compacting backfill pouring process. This prevents the grouting pipe from shifting, tilting, or collapsing due to the impact of the self-compacting backfill, ensuring that the grouting pipe always maintains the preset vertical posture and position. This is conducive to the uniform diffusion of the cement slurry injected through the grouting pipe into the pores of the backfill layer, thereby improving the uniformity of secondary compaction.

[0018] Preferably, in step S3, when laying the geogrid, the adjacent ends of the adjacent geogrids are overlapped and fixed with U-shaped nails.

[0019] By adopting the above technical solutions, it is beneficial to avoid gaps between geogrids, ensure that the geogrid's restraining effect on the backfill layer is continuous and uninterrupted, limit the displacement of the geogrid during the flow impact of self-compacting backfill material and during subsequent use, prevent relative sliding between the geogrid and the backfill material, and further improve the overall bearing capacity and crack resistance of the backfill body.

[0020] Preferably, in step S3, when laying the geogrid, the geogrid is bent close to the side wall of the backfill area to form a bent section, and the bent section of the geogrid 2 is attached and fixed to the side wall of the backfill area.

[0021] By adopting the above technical solution, it is beneficial to improve the lateral restraint effect of the geogrid on the backfill layer, and at the same time, it is convenient to transfer the lateral pressure generated by the backfill layer to the side wall structure of the backfill area, reduce the gap between the backfill and the side wall, enhance the integrity and cooperative bearing capacity of the backfill and the surrounding structure, and effectively prevent the backfill from sliding along the side wall.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. Backfilling is carried out using self-compacting backfill material. The material's own fluidity allows it to evenly fill the backfill area without the need for additional compaction. This effectively reduces the difficulty of backfilling in narrow areas of the wharf while ensuring the overall compactness of the backfill area.

[0023] 2. Using geogrids to constrain and limit the backfill layer helps to enhance the integrity and shear resistance of the backfill.

[0024] 3. Secondary grouting is performed on the backfill layer through pre-embedded grouting pipes. The injected cement grout further fills the residual pores inside the backfill layer, which helps to further improve the compactness of the backfill layer. Attached Figure Description

[0025] Figure 1 This is a schematic diagram used in this application to illustrate the backfill area of ​​the gravity wharf.

[0026] Figure 2 This is a schematic diagram of Example 1 used to illustrate the backfilling construction steps.

[0027] Figure 3 This is a schematic diagram of the location of the backfill layer and the geogrid in Example 1.

[0028] Figure 4 yes Figure 3 Enlarged schematic diagram of part A in the middle.

[0029] Explanation of reference numerals in the attached figures: 1. Backfill layer; 11. Grouting pipe; 12. Support frame; 121. Support bar; 122. Fixing plate; 2. Geogrid; 21. Bending section. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0031] This application discloses a method for backfilling narrow spaces in a gravity-type wharf. Example

[0032] A method for backfilling confined spaces in a gravity-type wharf, referring to Figures 1 to 3 This includes the following steps: S1: Preparation of self-compacting backfill material: Continuously graded crushed stone is selected, mixed with concrete curing agent and fiber materials, and water is added and stirred to form a self-compacting backfill material with self-compacting fluidity; the specific steps are as follows: S1.1: Continuously graded crushed stone with a particle size of 5-31.5mm is selected as aggregate; ordinary Portland cement with a mass ratio of 3% to 5% is selected as curing agent; and polypropylene short fiber material with a mass ratio of 0.3% to 0.5% is selected as reinforcing agent. S1.2: Put the above-mentioned crushed stone, cement, and polypropylene short fibers into a mixer and dry mix them evenly. Then add water and mix to form a self-compacting backfill. Control the moisture content of the self-compacting backfill to be 8% to 10%. Mix until the spread of the mixture reaches 700 to 800 mm to ensure that the self-compacting backfill has the ability to flow and fill.

[0033] In actual construction, after the self-compacting backfill is made, a trial mix verification is carried out. Specifically, test blocks are made to ensure that the compressive strength of the test blocks after 28 days of standard curing meets ≥3MPa, so as to meet the overall self-compacting and strength requirements of the self-compacting backfill.

[0034] S2: Layered backfilling of self-compacting backfill material: The self-compacting backfill material is continuously poured into the backfill area according to the design thickness of backfill layer 1 to form backfill layer 1; the self-compacting backfill material is used to form initial compaction by its own weight and fluidity; the specific steps are as follows: S2.1: Fabrication of Grouting Pipe 11: Refer to Figure 2 and Figure 3 A steel pipe is selected as the grouting pipe 11, ensuring that the length of the grouting pipe 11 is greater than the height of the backfill layer 1; several grouting holes are opened on the body of the grouting pipe 11 according to the quincunx arrangement requirements.

[0035] S2.2: Grouting pipe support and fixing: Refer to Figure 3 and Figure 4 The specific steps are as follows: S2.2.1: The grouting pipes 11 are installed in the backfill area at certain intervals.

[0036] S2.2.2: A support frame 12 is welded to the outer periphery of the grouting pipe 11. The support frame 12 includes a support rib 121, one end of which is welded to the outer periphery of the grouting pipe 11; a fixing plate 122 is welded to the end of the support rib 121 away from the grouting pipe 11. The fixing plate 122 has through holes for soil nailing.

[0037] S2.2.3: Make the fixing plate 122 at the support frame 12 fit against the side wall of the backfill area, insert the soil nail into the hole at the fixing plate 122 and drive it into the side wall of the backfill area, so as to fix the grouting pipe 11 in the backfill area through the support frame 12.

[0038] S2.3: Cover the outer periphery of the grouting pipe 11 with a filter screen, and make the filter screen cover the grouting holes on the grouting pipe 11; the two ends of the filter screen are tied to the grouting pipe 11 with steel wire; specifically, the filter screen is made of nylon mesh.

[0039] S2.4: Self-compacting backfill material pouring: A small chute is used to continuously pour the self-compacting backfill material from the edge of the backfill area towards the center to form backfill layer 1. During the pouring construction, the backfill thickness of each backfill layer 1 is controlled to be ≤1.5m to avoid uneven compaction caused by inter-layer discontinuity.

[0040] S2.5: Initial compaction of self-compacting backfill: After pouring, let stand for 3 to 4 hours to achieve initial compaction by utilizing the self-weight and fluidity of the self-compacting backfill. During this period, it is strictly forbidden to disturb the backfill layer 1.

[0041] S2.6: Grouting compaction: S2.6.1: After the strength of backfill layer 1 is ≥1.5MPa, connect the grouting pipe 11 to the air compressor and supply compressed air into the grouting pipe 11 through the air compressor to disperse the material residue remaining in the grouting hole and the filter screen, and ensure that the grout outlet channel is unobstructed. S2.6.2: Connect the grouting pipe 11 pre-embedded in the backfill layer 1 in step S2.2 to the high-pressure grouting pump. Pump the cement grout into the grouting pipe 11 through the high-pressure grouting pump and let it flow out through the grouting hole on the grouting pipe 11 to fill the remaining pores inside the backfill layer 1.

[0042] During grouting, the water-cement ratio of the cement grout should be 0.8 to 1.0; the grouting pressure should be controlled at 0.3 to 0.5 MPa; the grouting volume per hole should be controlled at 6% to 10% of the volume of the area; grouting can be stopped only when grouting is observed to return from adjacent grouting pipes 11.

[0043] By pre-embedding grouting pipes 11 in backfill layer 1 and grouting and compacting backfill layer 1 through grouting pipes 11, it is beneficial to further improve the overall compactness of backfill layer 1. At the same time, the pre-embedded grouting pipes 11 can serve as a supporting skeleton inside backfill layer 1, which is beneficial to improve the overall strength of backfill layer 1 and the shear resistance of adjacent backfill layers.

[0044] By setting the outer support frame 12 of the grouting pipe 11, the grouting pipe 11 can be supported and limited by the support frame 12 when it is subsequently supported, so as to limit the displacement of the grouting pipe 11 due to the impact of the backfill material pouring.

[0045] S3: Geogrid 2 Installation: Lay geogrid 2 on top of backfill layer 1, ensuring that the width of geogrid 2 matches the width of backfill layer 1; refer to Figure 2 and Figure 3 The specific steps are as follows: S3.1: Selection and cutting of geogrid 2: Select bidirectional geogrid 2 with tensile strength ≥50kN / m and elongation ≤10%. Cut the width of the geogrid according to the width of the backfill area to ensure that the geogrid 2 completely covers the top surface of the backfill layer 1.

[0046] When laying geogrid 2, the adjacent ends of adjacent geogrid 2 should be overlapped to ensure that the overlap length is ≥20cm. U-shaped nails should be used to fix the overlap at 50cm intervals. The U-shaped nails should penetrate into the backfill layer 1 to ensure that the geogrid 2 and the backfill layer 1 are tightly attached without any hollows or lifting.

[0047] The geogrid 2 is bent near the side wall of the backfill area to form a bent section 21. The bent section 21 of the geogrid 2 is attached to the side wall of the backfill area and fixed to the side wall of the backfill area by U-shaped nails.

[0048] S4: Repeat steps S2 to S3 until the backfilling is completed to the design elevation of the backfill area.

[0049] The grouting pipe 11 has an internal thread section and an external thread section at both ends. In step S4, when pre-embedding the grouting pipe 11 located in the current backfill layer 1 to be constructed, the grouting pipe 11 to be supported and the grouting pipe pre-embedded in the lower backfill layer 1 are spliced ​​together by the internal thread section and the external thread section at the nearest end. On the one hand, this helps to improve the integrity of the connection between the grouting pipes of adjacent backfill layers 1; on the other hand, it facilitates the positioning of the grouting pipe 11 and promotes the rapid support and fixation of the grouting pipe 11.

[0050] S5: Compaction Measurement: The specific steps are as follows: S5.1: Use ground-penetrating radar to non-destructively test the uniformity of the backfill area; S5.2: Randomly drill core samples from the backfill area; the core sample density must be ≥93%; if the test results are not up to standard, grouting pipe 11 is installed in the sampling area, and the defective area is further grouted through the installed grouting pipe 11.

[0051] S6: Settlement Monitoring: The specific steps are as follows: S6.1: Layout of observation points: Several settlement observation points shall be laid out on the top surface of the backfill at 5m intervals, and shall be marked and numbered. S6.2: Regular monitoring: Monitor once a week in the first month after backfilling is completed, once every two weeks from the second to the sixth month, once a month thereafter, and continue monitoring for one year. Example

[0052] The difference between Example 2 and Example 1 is that: Reference Figure 3 and Figure 4 In step S2.2, after the grouting pipe 11 is installed and fixed, a sealing airbag is inserted into the inner cavity of the grouting pipe 11 and the sealing airbag is inflated. The inflated sealing airbag is used to temporarily seal the grouting holes of the grouting pipe 11, which limits the concrete slurry and graded crushed stone from entering the grouting pipe 11 when the self-compacting backfill material is poured, thus preventing the grouting pipe 11 from becoming blocked.

[0053] In step S2.6, when grouting is performed through the grouting pipe 11, the gas in the sealing airbag is released and the sealing airbag is pulled out of the grouting pipe 11.

[0054] The sealing airbag is annular, and a support rod is inserted through the inner circumference of the sealing airbag. The inner circumference of the support rod is fixed to the inner circumference of the sealing airbag with glue, so that the sealing airbag can be moved into the inner cavity of the grouting pipe 11 through the support rod.

[0055] This application utilizes self-compacting backfill material for backfilling construction. Its inherent fluidity allows for uniform filling of the backfill area without the need for additional compaction, effectively reducing the difficulty of backfilling in narrow areas while ensuring the overall compactness of the backfill area. By laying geogrid 2 on backfill layer 1, the integrity and shear resistance of the backfill body are enhanced, limiting the lateral deformation of backfill layer 1. Simultaneously, secondary grouting is performed on backfill layer 1 using grouting pipes 11 pre-embedded in it, which further fills the residual pores within backfill layer 1, improving its compactness.

[0056] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for backfilling confined spaces in a gravity-type wharf, characterized in that: Includes the following steps: S1: Preparation of self-compacting backfill: Select continuously graded crushed stone, add concrete curing agent and reinforcing agent, add water and stir to form self-compacting backfill with self-compacting fluidity; S2: Layered backfilling of self-compacting backfill material: The self-compacting backfill material is poured into the backfill area according to the design thickness of the backfill layer (1) to form the backfill layer (1); the self-weight and fluidity of the self-compacting backfill material are used to form preliminary compaction; S3: Geogrid (2) laying: Geogrid (2) is laid on top of backfill layer (1) to ensure that the width of geogrid (2) matches the width of backfill layer (1); S4: Repeat steps S2 to S3 until the backfill layer (1) is applied to the design elevation of the backfill area; S5: Compaction monitoring: Ground-penetrating radar is used to non-destructively test the uniformity of the backfill area, and random core samples are taken. S6: Settlement monitoring: Set up observation points on the top surface of the backfill structure and regularly monitor the settlement of the backfill area.

2. The method according to claim 1, wherein the method is characterized by: In step S2, when backfilling with self-compacting backfill material, the self-compacting backfill material is poured from the edge of the backfill area toward the center of the backfill area.

3. The method according to claim 1, wherein the method is characterized by: In step S2, before the self-compacting backfill material is backfilled, several grouting pipes (11) are vertically supported in the backfill area, and several grouting holes are arranged around the outer periphery of the grouting pipes (11). After the backfill layer (1) is initially compacted, cement grout is injected into the backfill layer (1) through the grouting pipe (11) to fill the internal pores of the backfill layer (1) and achieve secondary compaction of the backfill layer (1).

4. The method according to claim 3, wherein: In step S2, before grouting into the backfill layer (1) through the grouting pipe (11), compressed air is supplied into the grouting pipe (11) to disperse the grouting holes of the grouting pipe (11).

5. The method for backfilling confined spaces in a gravity-type wharf according to claim 3, characterized in that: In step S2, when pre-embedding the grouting pipe (11), a filter screen is wrapped around the outer periphery of the grouting pipe (11), and the filter screen covers the grouting hole on the outer periphery of the grouting pipe (11).

6. The method for backfilling confined spaces in a gravity-type wharf according to claim 5, characterized in that: In step S2, when pre-embedding the grouting pipe (11), a support frame (12) is welded to the outer periphery of the grouting pipe (11), and the end of the support frame (12) away from the grouting pipe (11) is fixed to the side wall of the backfill area.

7. The method for backfilling confined spaces in a gravity-type wharf according to claim 1, characterized in that: In step S3, when laying the geogrid (2), the adjacent ends of the adjacent geogrids (2) are overlapped and fixed with U-shaped nails.

8. The method for backfilling confined spaces in a gravity-type wharf according to claim 7, characterized in that: In step S3, when laying the geogrid (2), the geogrid (2) is bent close to the side wall of the backfill area to form a bent section (21), and the bent section (21) of the geogrid (2) is attached and fixed to the side wall of the backfill area.

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