Method for repairing cracking of large-thickness earthing long-distance pipeline

Abstract

The invention provides a large-thickness earthing long-distance pipeline cracking repairing method. The method comprises the following steps that firstly, double-liquid cement paste is injected from the interior of a to-be-repaired pipeline to a drilled hole outside the pipeline, and then splitting grouting is conducted; the method comprises the following steps: grooving a crack in a pipeline, embedding a water stop needle, smearing a grooving part with a sealing adhesive, and injecting an epoxy resin structural adhesive at the water stop needle to seal the crack of the pipeline; carbon fiber cloth is pasted to the cracks injected with the epoxy resin structural adhesive, the surfaces of the cracks are coated with dipping adhesive to seal the carbon fiber cloth after pasting is completed, and the tensile strength of the pipeline at the cracks is enhanced; and finally, a steel ring lining is installed in the pipeline, and the steel ring and the pipeline are tightly attached through expansion bolts and sticky steel glue. The whole construction process is completed in the pipeline, construction is convenient and fast, grouting and crack treatment in construction play a role in protecting the steel bars in the pipeline, it is ensured that the steel bars are not corroded any more, and the loss of compressive strength of the cracked part of the pipeline is greatly made up.

Description

Technical Field

[0001] The present invention relates to the field of engineering, in particular to a method for repairing cracks in long-distance pipelines with a thick soil cover, which is applied to repair cracks in drainage pipelines and also serves as a foundation treatment method around the pipelines. Background Art

[0002] Concrete pipes are pipes made of concrete or reinforced concrete, typically buried underground, used to transport fluids such as water, oil, and gas. They are widely used in municipal engineering and industrial fields. However, over long-term use, underground concrete pipes are prone to damage or cracking due to corrosion from the fluids they transport or external forces. This can affect fluid transport efficiency, lead to leakage, and cause waste and pollution. In severe cases, it can also cause road collapse, impacting the operational status of existing roads.

[0003] Current repair options for cracks in underground concrete pipes fall into two main categories: The first involves excavation and replacement. While this approach can fundamentally address the problem, it is slow, has a significant impact on the traffic environment, is expensive, generates significant construction waste, pollutes the environment, and requires the pipe network to be shut down, resulting in significant financial and material costs and impacts the lives of urban residents. This is particularly true for pipes buried at greater depths, which are more difficult to excavate and replace. The second category involves trenchless repair, which generally includes pipe insertion, new cement mortar lining, new epoxy resin lining, slip-on hose lining, insertion of smaller-diameter pipes, steel plate reinforcement, and CIPP in-situ curing. While some of these methods can address pipeline leakage, they have limitations and shortcomings. Some only provide anti-seepage protection but fail to reinforce the pipe, failing to achieve a complete reinforcement effect. Potential hazards cannot be completely eliminated. Many methods result in a reduction in the existing pipe diameter, and the repair costs are relatively high, with most repairs targeting small-diameter pipes.

[0004] In addition, for pipelines buried in deep soil, the backfill area is relatively narrow during the installation and backfilling of the pipeline. It can only be compacted with a manual rammer, which has a poor compaction effect and easily leads to poor backfilling effect. Moreover, when installing and backfilling the pipeline, most design drawings require original soil backfill, not sand, gravel and other dense and strong materials. The original soil at the construction site is generally not a good backfill material. In addition, when the compaction effect is not good, it is easy to be carried away by the groundwater outside the pipeline. Especially when there is an abundant water source near the buried area of the pipeline and the moisture content under the ground is high, most of the backfill soil under the pipeline will be carried away in the presence of abundant groundwater in the surrounding area, resulting in hollowing under the pipeline and inability to effectively support the pipeline. If this area is not treated during the pipeline crack repair process, even after the repair, there is no effective support under the pipeline, the pressure above the pipeline becomes relatively large, and cracks will continue to appear on both sides of the pipeline.

[0005] Therefore, it is necessary to provide a long-distance pipeline crack repair method with thick covering soil that is economical, efficient, has good repair effect, and can backfill the hollow area under the pipeline during the repair process to avoid cracks in the repaired pipeline again. Summary of the Invention

[0006] In response to the defects of the existing technology, the present invention has developed a method for repairing cracks in long-distance pipelines with thick soil covering based on actual repair work. This repair method can repair pipelines with thick soil covering under the road without excavating the covering soil, reducing the cost and difficulty of re-excavating and replacing the pipeline, improving repair efficiency and reducing costs. At the same time, grouting outside the pipe can also stabilize the soil under the road.

[0007] In order to achieve the above technical objectives, the present invention provides a method for repairing cracks in long-distance pipelines covered with thick soil, which is aimed at repairing cracks in underground pipelines with a diameter greater than 1.5m. The method is characterized in that it specifically includes the following steps:

[0008] S1. Drill holes from the inside of the pipeline to be repaired toward the outside and inject dual-liquid cement slurry. The length of the drilled and grouting area is greater than the length of the cracked area. Grouting holes are opened on both sides of the lower middle area of the pipeline and spaced 1.8-2.2 meters apart along the pipeline axis.

[0009] S2. After the double-liquid cement slurry injection is completed in step S1, before the double-liquid cement slurry is initially set, a flower pipe is used to perform split grouting in the original grouting hole;

[0010] S3. Create grooves in the cracked area of the pipe, distributed along the length of the crack. Install water-stopping needles in the grooves at intervals of 25 to 35 cm. Apply sealing glue to the grooved areas where water-stopping needles are not installed.

[0011] S4. After applying sealant to treat the cracks, inject epoxy resin structural adhesive through the water-stop needle to seal the cracks in the pipe and strengthen the concrete strength at the defective area.

[0012] S5. After the epoxy resin structural adhesive is injected, the protruding water-stop needle is cut off and carbon fiber cloth is applied to the crack. After the carbon fiber cloth is attached, the impregnating adhesive is applied to the surface to seal the carbon fiber cloth and enhance the tensile strength of the pipe at the crack.

[0013] S6. Install multiple steel ring liners in the pipeline in the crack area, with the spacing between the steel ring liners being 0.6 to 1.4 meters. Each steel ring liner is assembled from multiple arc-shaped steel ring pieces, and two adjacent arc-shaped steel ring pieces are fixed and spliced together with bolts. The steel ring pieces are tightly attached to the inner wall of the pipeline using expansion bolts and steel glue.

[0014] A better technical solution of the present invention: In the S1 step, a drilling rig is used to distribute multiple groups of grouting holes along the axial direction of the pipeline at intervals of 2m, each group includes two grouting holes symmetrically arranged on both sides of the middle and lower areas of the pipeline, and the two grouting holes on the same annular surface are respectively arranged in the four to five o'clock area and the seven to eight o'clock area of the pipeline annular surface.

[0015] A preferred technical solution of the present invention is as follows: the grouting pipe joint for drilling and injecting double-liquid cement slurry in step S1 adopts a Φ32*2.5 seamless steel pipe, and the double-liquid cement slurry is prepared by mixing P·O42.5 cement, water and water glass in a ratio of 1:0.8:0.3. The grouting pressure does not exceed 0.05 MPa, and the lowest point of the grouting depth is the top elevation of the pipeline trench cushion layer.

[0016] A preferred technical solution of the present invention: in the S2 step, Φ25PVC plastic flower tubes are used for splitting grouting, holes are opened within 1m of the lower part of the grouting flower tubes, the hole spacing of the grouting flower tubes is 90-110mm, and the hole diameter is 4.5-5.5mm; P·O42.5 cement slurry is used for splitting grouting, the water-cement ratio is prepared according to 1:0.5, the grouting pressure is controlled at 1.0MPa, and the grouting amount should be based on 100Kg of cement slurry for each grouting hole.

[0017] A more preferred technical solution of the present invention: the grooves in the crack parts in step S3 are triangular grooves with a width of 1.8 to 2.2 cm and a depth of 0.8 to 1.2 cm; the water-stop needles are buried at intervals of 25 to 35 cm.

[0018] A preferred technical solution of the present invention: in step S3, the tensile strength of the sealing glue is not less than 25 MPa, the tensile elastic modulus is not less than 1500 MPa, and the compressive strength is not less than 50 MPa;

[0019] A more preferred technical solution of the present invention: in the step S4, the epoxy resin structural adhesive injected at the water stop needle has a tensile strength of not less than 30 MPa, a tensile elastic modulus of not less than 2400 MPa, and a compressive strength of not less than 60 MPa.

[0020] A preferred technical solution of the present invention: the width of the carbon fiber cloth pasted on the crack in the S5 step is 20 cm to 25 cm, the tensile strength of the carbon fiber cloth is not less than 3000 MPa, and the tensile elastic modulus is not less than 2*105 MPa; the tensile strength of the impregnating glue is not less than 35 MPa, and the tensile elastic modulus is not less than 2000 MPa.

[0021] A better technical solution of the present invention: the thickness of the steel ring lining in the S4 step is 5-10mm and the width is 10-20cm; each steel ring lining is assembled by four 90° fan-shaped steel ring pieces connected by bolts, and the steel plate at the assembly joint extends 3-6cm long and is provided with bolt holes. When assembling every two fan-shaped steel plates, the bolts must be equipped with gaskets.

[0022] Beneficial effects of the present invention:

[0023] (1) The entire construction process of the present invention is completed in the pipeline, which is convenient and does not require large-scale construction machinery. In particular, crack treatment, carbon fiber cloth pasting and lining steel ring installation only require skilled workers;

[0024] (2) The present invention fully integrates and reinforces the high-pressure cement slurry with the soil around the pipeline through grouting, so that the soil outside the pipeline forms a strong and solid supporting enclosure, ensuring that the water in the soil outside the pipeline no longer penetrates into the pipeline; and the slurry will also penetrate into the cracks in the pipeline, wrapping up the broken steel bars to prevent the steel bars from rusting again; during construction, grouting and crack treatment both protect the steel bars in the pipeline, ensuring that the steel bars will no longer rust, and greatly compensate for the loss of compressive strength at the cracked parts of the pipeline;

[0025] (3) The repair cost of the present invention is low and the repair work period is short, which has a good reference significance for similar pipeline repair work. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic top view of the pipeline drilling and grouting in the present invention;

[0027] Figure 2 This is a schematic cross-sectional view of the pipeline drilling and grouting in the present invention;

[0028] Figure 3 yes Figure 2 An enlarged schematic diagram of the midpoint A;

[0029] Figure 4 This is a schematic diagram of the pipeline crack repair structure in the present invention;

[0030] Figure 5 This is a schematic diagram of the layout of the carbon fiber cloth for repairing pipeline cracks in the present invention;

[0031] Figure 6 This is an overall schematic diagram of the pipeline crack repair structure of the present invention;

[0032] Figure 7 It is a schematic diagram of the steel ring lining of the pipeline in the present invention;

[0033] Figure 8 It is a structural schematic diagram of the steel ring piece in the present invention.

[0034] In the figure: 1—pipeline, 2—grouting hole, 3—grouting reinforcement layer, 4—grouting pipe joint, 5—split grouting flower pipe, 6—steel ring lining, 7—crack, 8—groove, 9—waterstop needle, 10—sealing glue, 11—epoxy resin structural glue, 12—carbon fiber cloth, 13—steel ring piece, 14—connecting bolt, 15—expansion bolt, 16—steel adhesive. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the embodiments. Figures 1 to 8 The drawings are all in the embodiments, drawn in a simplified manner, and are only used for the purpose of clearly and concisely illustrating the embodiments of the present invention. The technical solutions shown in the following drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] This example involves a practical repair of a drainage pipe buried beneath a municipal road. In this project, each section of the pipe is two meters long. Surveys revealed cracks along approximately 1.2 kilometers of the pipe. Most of these cracks were concentrated at the top of the pipe, with some cracks extending along the sides, up to 1 cm wide. The cracks in each section ran essentially the entire length of the pipe. The pipes in this section were constructed of D1800, Grade III reinforced concrete pipes, and the soil depth within this section ranged from 6 to 9 meters. When this problem occurred, the road was still under construction, with the base course already underway. Excavating the pipe and reburying a new one would have significantly delayed the project and incurred significant costs, necessitating a trenchless repair approach.

[0037] Analysis of the project revealed that the municipal road, designated a main urban artery, has a design width of 40 meters and features four lanes in both directions. The pipeline slope ranged from 3% to 5%, with multiple wells and continuous waterfalls located throughout. The pipeline foundation was designed to be gravel, with medium-coarse sand backfill. However, a design change resulted in the backfill being replaced with excavated soil. Conventional road design typically requires C20 concrete sockets for concrete pipes larger than 800mm in diameter. However, this method was not used for pipeline burial in this area, which was the root cause of the pipeline cracking. Because the pipeline is covered with soil at a depth of 6-9 meters, cracks mainly appear at the top of the pipe and on both sides of the pipe. The actual stress range of the pipeline is roughly the arc-shaped part of 1 / 4 of the top of the pipe. The backfill of pipe top II and III is not dense, and the soil layer on the top of the pipe has not formed a soil arch. The backfill quality of area I on both sides of the pipe is also not ideal. If the soil layer on the top of the pipe continues to settle in the later stage, the pipe wall near area I on both sides of the pipe will expand outward. The pipeline will be elliptical, the inner wall of the top of the pipe will be subjected to positive bending moment, and the inner wall of the bottom of the pipe will be subjected to negative bending moment. The actual pressure on the pipeline is less than the upward reaction force of the pipeline foundation, resulting in cracks at the bottom of the pipe.

[0038] In order to solve the above problems, the project team adopted a long-distance pipeline crack repair method with a thick soil cover in the present invention. The specific repair process is as follows:

[0039] S1. Figure 1 and Figure 2 As shown, a drilling rig is used to drill multiple groups of grouting holes 2 along the axial direction of the pipeline at intervals of 2m, each group including two grouting holes 2 symmetrically arranged on both sides of the middle and lower area of the pipeline 1, and the two grouting holes 2 on the same annular surface are respectively arranged at a 45° position on the lower part of the annular surface of the pipeline 1, and the drilling rig adopts a handheld drilling coring machine; each grouting hole 2 passes through the pipe wall of the pipeline 1. After the grouting holes 2 are drilled, a grouting pipe joint 4 is installed at the position of the grouting hole 2, and the grouting equipment is connected to inject double-liquid cement slurry toward the outside of the pipe wall; the grouting pipe joint adopts a Φ32*2.5 seamless steel pipe, and the double-liquid cement slurry is prepared by mixing P·O42.5 cement, water and water glass in a ratio of 1:0.8:0.3. The grouting pressure does not exceed 0.05MPa, and the grouting depth is the top elevation of the pipeline groove cushion layer. The grouting amount of each grouting hole is based on the cement slurry seeping out of the pipe joint observed by a person in the pipeline;

[0040] S2. Before the initial setting of the primary grouting, a secondary splitting grouting tube 5 is buried in the original grouting hole 2. The splitting grouting tube 5 is a Φ25 PVC plastic tube with a 100mm spacing and a 5mm hole diameter. Grouting holes are only set within 1m of the lower part of the grouting tube. To prevent external sediment from flowing into the grouting tube during grouting, all grouting holes are sealed with electrical tape before burying the PVC tube. The secondary splitting grouting also uses P·O42.5 cement slurry with a water-cement ratio of 1:0.5. The grouting pressure is controlled at 1.0 MPa, and the grouting volume is based on 100 kg of cement slurry per grouting hole.

[0041] S3. Figure 3 and Figure 4 As shown, a triangular groove is opened at the crack 7 in the pipe 1, and the grooves 8 are distributed along the length direction of the crack, with a groove depth of 1 cm and a width of 2 cm. Water-stop needles 9 are buried in the groove at intervals of 30 cm, and sealing glue 10 is applied to the groove area where the water-stop needles 9 are not buried; after the sealing glue 10 dries, epoxy resin structural glue 11 is injected into the crack of the pipe 1 through the water-stop needle 9 to reinforce the strength of the concrete at the crack, and at the same time protect the steel bars in the pipe from further rusting; the tensile strength of the sealing glue 10 is not less than 25 MPa, the tensile elastic modulus is not less than 1500 MPa, and the compressive strength is not less than 50 MPa; the epoxy resin structural glue 11 injected at the water-stop needle has a tensile strength of not less than 30 MPa, a tensile elastic modulus is not less than 2400 MPa, and a compressive strength of not less than 60 MPa.

[0042] S4. Figure 5 As shown, carbon fiber cloth 12 is pasted to the crack 7 where epoxy resin structural adhesive 11 has been injected. The area where the carbon fiber cloth 12 needs to be pasted is polished and smoothed, and the surface dust is blown clean. The impregnating glue is promptly applied to the carbon fiber cloth 12 and pasted to the surface. A 20 cm wide carbon fiber cloth 12 is used to paste each crack. After the carbon fiber cloth 12 is pasted, the surface must be coated with impregnating glue to seal the surface and edges of the carbon cloth; the tensile strength of the pipe at the crack is enhanced; the tensile strength of the carbon fiber cloth 12 is not less than 3000 MPa, and the tensile elastic modulus is not less than 2*105 MPa; the tensile strength of the impregnating glue is not less than 35 MPa, and the tensile elastic modulus is not less than 2000 MPa.

[0043] S5. Figure 6 and Figure 7As shown, multiple steel ring liners 6 are installed in the pipe in the crack area; each section of the pipe 1 in the embodiment is 2m long, and two steel ring liners 6 are arranged in each section of the pipe 1. The spacing between the two steel ring liners 6 is 0.6-0.7m, and the spacing between the steel ring liners of two adjacent sections of the pipe 1 is 1.3-1.4m; the steel ring is 5mm thick and 10cm wide. Each steel ring must be painted with anti-rust paint in advance to ensure that the paint is dry and effective. Each steel ring is assembled by four 90° fan-shaped steel ring pieces 13 connected by bolts 14. The steel ring and the concrete pipe are tightly attached by expansion bolts 15 and adhesive steel glue 16; as shown Figure 8 As shown, each steel ring segment 13 has a 5cm extension at the joint. Two M12 bolt holes are provided, with a center-to-center spacing of 5cm and a center-to-edge distance of 2.5cm. When assembling two sector-shaped steel plates, the bolts must be fitted with washers. Five bolt holes must be reserved for each sector-shaped steel ring, spaced 24cm apart. After assembly, the steel plate lining must be securely attached to the inner wall of the pipe using steel glue and expansion bolts. Finally, the steel plate and bolts must be treated to prevent rust.

[0044] The above-mentioned method allowed the road's drainage pipe to be repaired in just one month, at a relatively low cost and with readily available materials. This method ensured that the municipal road's drainage system could be connected to the drainage system of the existing road to the north, providing a valuable reference for similar pipe repairs. After the pipe was repaired and connected, construction crews conducted multiple inspections of the drainage pipe. The previously installed carbon fiber sheeting and steel rings were found to be in good working order, with no new cracks found.

[0045] In the above embodiment, the pipeline repair construction is convenient, does not require large-scale construction machinery, has low repair costs, and is short in repair work period. After the pipeline repair is completed, no external water seeps into the pipeline cracks, and the effect is significant. Grouting and crack treatment during construction both protect the steel bars in the pipeline, ensuring that the steel bars will no longer rust, and greatly compensate for the loss of compressive strength of the cracked parts of the pipeline.

[0046] The above is merely one embodiment of the present invention, and its description is relatively specific and detailed. However, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and such modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for repairing cracks in long-distance pipelines covered with thick soil, which is aimed at repairing cracks in underground pipelines with a diameter greater than 1.5m, characterized in that: The specific steps include: S1. Drill holes from the inside of the pipeline to be repaired toward the outside and inject dual-liquid cement slurry. The length of the drilled and grouting area is greater than the length of the cracked area. Grouting holes are opened on both sides of the lower middle area of the pipeline and spaced 1.8-2.2 meters apart along the pipeline axis. S2. After the double-liquid cement slurry injection is completed in step S1, before the double-liquid cement slurry is initially set, a flower pipe is used to perform split grouting in the original grouting hole; S3. Create grooves in the cracked area of the pipe, distributed along the length of the crack. Install water-stopping needles in the grooves at intervals of 25 to 35 cm. Apply sealing glue to the grooved areas where water-stopping needles are not installed. S4. After applying sealant to treat the cracks, inject epoxy resin structural adhesive through the water-stop needle to seal the cracks in the pipe and strengthen the concrete strength at the defective area. S5. After the epoxy resin structural adhesive is injected, the protruding water-stop needle is cut off and carbon fiber cloth is applied to the crack. After the carbon fiber cloth is attached, the impregnating adhesive is applied to the surface to seal the carbon fiber cloth and enhance the tensile strength of the pipe at the crack. S6. Install multiple steel ring liners in the pipeline in the crack area, with the spacing between the steel ring liners being 0.6 to 1.4 meters. Each steel ring liner is assembled from multiple arc-shaped steel ring pieces, and two adjacent arc-shaped steel ring pieces are fixed and spliced together with bolts. The steel ring pieces are tightly attached to the inner wall of the pipeline using expansion bolts and steel glue.

2. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: In the step S1, a drilling rig is used to distribute multiple groups of grouting holes along the axial direction of the pipeline at intervals of 2m, each group includes two grouting holes symmetrically arranged on both sides of the middle and lower areas of the pipeline, and the two grouting holes on the same annular surface are respectively arranged in the four to five o'clock area and the seven to eight o'clock area of the pipeline annular surface.

3. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: In step S1, the grouting pipe joint for drilling and injecting double-liquid cement slurry adopts a Φ32*2.5 seamless steel pipe. The double-liquid cement slurry is prepared by mixing P·O42.5 cement, water and water glass in a ratio of 1:0.8:0.

3. The grouting pressure does not exceed 0.05 MPa, and the lowest point of the grouting depth is the top elevation of the pipeline trench cushion layer.

4. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: In the S2 step, Φ25PVC plastic flower pipe is used for splitting grouting, and holes are opened within 1m of the lower part of the grouting flower pipe. The hole spacing of the grouting flower pipe is 90-110mm, and the hole diameter is 4.5-5.5mm; P·O42.5 cement slurry is used for splitting grouting, and the water-cement ratio is prepared according to 1:0.

5. The grouting pressure is controlled at 1.0MPa, and the grouting amount of each grouting hole is 100Kg of cement slurry.

5. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: The grooves at the cracks in step S3 are triangular grooves with a width of 1.8 to 2.2 cm and a depth of 0.8 to 1.2 cm; the water-stop needles are buried at intervals of 30 cm.

6. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: In the step S3, the tensile strength of the sealing glue is not less than 25 MPa, the tensile elastic modulus is not less than 1500 MPa, and the compressive strength is not less than 50 MPa.

7. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: In the step S4, the epoxy resin structural adhesive injected at the water stop needle has a tensile strength of not less than 30 MPa, a tensile elastic modulus of not less than 2400 MPa, and a compressive strength of not less than 60 MPa.

8. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: The width of the carbon fiber cloth pasted on the crack in the S5 step is 20cm to 25cm, the tensile strength of the carbon fiber cloth is not less than 3000MPa, and the tensile elastic modulus is not less than 2*105MPa; the tensile strength of the impregnating glue is not less than 35MPa, and the tensile elastic modulus is not less than 2000MPa.

9. The method for repairing cracks in a long-distance pipeline covered with thick soil according to claim 1, characterized in that: The thickness of the steel ring lining in step S4 is 5-10mm and the width is 10-20cm; each steel ring lining is assembled by four 90° sector-shaped steel ring pieces connected by bolts, and the steel plate at the assembly joint extends 3-6cm long and is provided with bolt holes. When assembling every two sector-shaped steel plates, the bolts must be equipped with gaskets.

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