In-situ transformation method for non-pressure pipeline

Abstract

According to the in-situ transformation method of the non-pressure pipeline, the diversion open channel is utilized, and safe and efficient transformation of the large-diameter non-pressure pipeline is achieved while the continuous water passing function of the pipeline in the construction period is ensured; a combined structure of a Larsen steel sheet pile supporting system, an enclosing purlin and an inner support is adopted, and a concrete bottom sealing and waterproof treatment process is matched, so that a temporary flow guide channel with excellent rigidity and waterproof performance is constructed, and the leakage and deformation risks existing in a traditional construction method are effectively solved; and meanwhile, large-scale pipeline relocation and reformation are avoided through in-situ reformation, and the influence on the surrounding environment is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of municipal engineering, and in particular relates to an in-situ transformation method for a pressure-free pipeline. Background Art

[0002] In urban underground pipeline construction and renovation projects, the in-situ replacement of large-diameter, non-pressure pipelines has always been a technical challenge in municipal engineering. Traditional pipeline management techniques primarily include relocation, suspension, and in-situ reinforcement. However, these conventional construction methods have significant limitations when dealing with large-diameter, non-pressure pipelines with specialized functional requirements, such as flood discharge pipes and sewage pipes. These pipelines often perform critical regional flood control and drainage functions, and continuous water flow must be maintained during construction. This makes it difficult to implement either relocation or decommissioning and rebuilding pipelines.

[0003] The main problems with existing technologies are as follows: First, due to limited above- and underground space in urban built-up areas, large-diameter pipelines are generally not suitable for relocation; second, during foundation pit construction, conventional pipe suspension protection solutions cannot meet the structural safety and water flow requirements of large-diameter pipelines; and third, in-situ reinforcement technology cannot address leakage and structural hazards caused by aging pipelines. Especially in pipeline reconstruction projects that serve as flood discharge and drainage systems, interrupting pipeline function during construction directly threatens regional flood control safety and may cause significant social and economic losses.

[0004] In the construction industry, when foundation pit support and excavation encounter these special pipelines, traditional treatment methods often have adverse effects on foundation pit stability, construction progress, and subsequent main structure construction. Engineering practice has shown that using conventional technical solutions to retrofit large-diameter non-pressure pipelines not only results in long construction periods and high costs, but also poses quality and safety risks such as pipeline deformation and foundation pit leakage, posing severe challenges to the protection of surrounding buildings and underground pipelines.

[0005] Therefore, there is an urgent need to develop a new pipeline in-situ transformation technology that can maintain the normal water flow function of the pipeline while ensuring construction safety and quality. Summary of the Invention

[0006] The present invention provides an in-situ transformation method for a pressure-free pipeline, which is used to solve the problems of many difficulties and risks faced in the renovation of large-diameter pressure-free pipelines in the prior art.

[0007] The present invention provides an in-situ transformation method for a pressure-free pipeline, comprising the following steps: S1. Determine the buried depth and direction of the non-pressure pipeline to be renovated, build reinforced concrete inspection wells in situ at both ends of the non-pressure pipeline in the foundation pit, and open a temporary diversion hole on the side of the inspection well perpendicular to the non-pressure pipeline; S2. Construct a new diversion channel in parallel with the pressure-free pipeline in the foundation pit. Use Larsen steel sheet piles on both sides of the diversion channel for support, and set perimeter purlins and internal supports between the Larsen steel sheet piles. S3. Lay a waterproof layer in the diversion channel and pour a concrete cushion on the waterproof layer. Build brick walls on both sides of the diversion channel and apply waterproof plastering treatment. S4. Set up a cutoff wall in the two inspection wells to block the original non-pressure pipe opening between the two inspection wells, and divert the water flow in the original non-pressure pipe into the diversion channel through the temporary diversion hole; S5. Excavate the original non-pressure pipeline section, remove the old pipeline, and build a new box culvert in the original location; S6. After the box culvert is accepted, the cut-off wall will be moved to the temporary diversion hole to cut off the flow, and the water flow will be introduced from the diversion open channel into the newly built box culvert, and the temporary diversion hole will be sealed to complete the in-situ transformation of the pressure-free pipeline.

[0008] Compared with the existing technology, the benefits of the present invention are as follows: the use of diversion channels ensures the continuous water flow of the pipeline during construction while achieving the safe and efficient transformation of large-diameter pressure-free pipelines; the combination of the Larsen steel sheet pile support system, purlins and internal supports, combined with concrete bottom sealing and waterproofing treatment technology, constructs a temporary diversion channel with excellent rigidity and waterproof performance, effectively solving the risks of leakage and deformation in traditional construction methods; at the same time, through in-situ transformation, large-scale pipeline relocation is avoided, greatly reducing the impact on the surrounding environment.

[0009] Furthermore, in step S1, the outer structure of the temporary diversion tunnel is pre-buried with Larsen steel sheet piles and waterstop steel plates; the Larsen steel sheet piles are driven into the soil layer at least 6m below, and the waterstop steel plates and Larsen steel sheet piles are overlapped and fully welded.

[0010] Furthermore, in step S2, the support structure of the diversion channel includes Larsen steel sheet piles, perimeter purlins and internal supports; the perimeter purlins are H-shaped steels welded and fixed to the Larsen steel sheet piles; the internal supports are steel pipes with a horizontal spacing of 2.5m.

[0011] Furthermore, in step S3, the waterproof layer is polyethylene colored strip cloth; the thickness of the concrete cushion layer is 100 mm; the brick wall is a 240 mm thick solid brick wall, and the surface is plastered with waterproof mortar.

[0012] Furthermore, step S5 includes: reserving a 1m wide slope on both sides of the diversion channel to the pit bottom elevation, using 100mm thick C20 shotcrete to protect the slope surface, then excavating the original non-pressure pipeline section, dismantling the old pipeline, and building a new box culvert in situ.

[0013] Furthermore, in step S4, the break wall includes a steel cage frame and sandbags. The steel cage frame is made of welded steel bars, and sandbags are stacked layer by layer inside. The steel cage frame is provided with lifting ears.

[0014] Furthermore, in step S5, the box culvert is a cast-in-place reinforced concrete structure, the outer contour of which matches the flow requirement of the original non-pressure pipeline, and the side walls, top plate and bottom plate of the box culvert are all subjected to haunch treatment.

[0015] Furthermore, in step S6, when sealing the temporary diversion hole, micro-expansive concrete is used for pouring, and the strength of the expansive concrete is at least one grade higher than that of the concrete of the inspection well.

[0016] Furthermore, after step S6, the method further includes: excavating the remaining earthwork in the foundation pit after the construction of the diversion channel and the box culvert is completed.

[0017] Furthermore, the locking mouth of the Larsen steel sheet pile is coated with grease, and fiber-rich cotton batting is used to caulk the seams after injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic plan view of the box culvert portion and the temporary diversion open channel for the transformation of the non-pressure pipeline in the foundation pit in one embodiment of the present invention; Figure 2 This is a top view of a newly built inspection well connected to a diversion channel in one embodiment of the present invention; Figure 3 A schematic cross-sectional view of a non-pressure pipeline and an open diversion channel in one embodiment of the present invention; Figure 4 Schematic diagram of a steel cage for a break wall in one embodiment of the present invention.

[0019] Description of reference numerals: 1. Box culvert; 2. Inspection well; 3. Larsen steel sheet pile; 4. Diversion channel; 6. Concrete cushion; 7. Waterproof layer; 8. Slope; 9. Brick wall; 10. Purlin; 11. Internal support; 13. Waterstop steel plate; 14. Temporary diversion opening; 15. Lifting lug. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] The present invention provides an in-situ renovation method for pressure-free pipelines, which is particularly suitable for renovation projects of important flood discharge pipelines and rainwater and sewage pipelines in urban built-up areas. While ensuring regional flood control safety, it achieves multi-objective optimization of construction quality, project costs and environmental protection, and provides a reliable technical solution for similar projects.

[0022] Specifically, see Figures 1 to 4 , a method for in-situ transformation of a pressure-free pipeline, comprising the following steps: (1) Determine the depth and direction of the underground large-diameter pressure-free pipeline. Combined with the foundation pit support and earthwork excavation, the foundation pit support and earthwork excavation are carried out in layers and sections until the elevation is 500mm above the pipeline top. Construction is then stopped to prevent the flood discharge pipe from floating and deforming after the earthwork excavation on the large-diameter pressure-free pipeline. New reinforced concrete inspection wells 2 are built in situ at both ends of the pressure-free pipeline in the foundation pit. The structural dimensions of the inspection well 2 should meet the requirements of the inspection well 2 well wall construction. A temporary diversion hole 14 with a size of 2000mm×2000mm is opened on the side of the inspection well 2 perpendicular to the flood discharge pipe. The temporary diversion hole 14 structure extends 500mm. Larsen steel sheet piles 3 are pre-buried on both sides of the temporary diversion hole 14 structure and driven 6m below the soil layer. Water-stop steel plates 13 are pre-buried in the upper and lower top plates and bottom plates respectively. The steel sheet piles on both sides are overlapped and fully welded to set connection points for the subsequent connection of the steel sheet pile diversion channel 4.

[0023] (2) 12m Larsen IV steel sheet piles were used for positioning and injection on both sides of the diversion channel 4 in the foundation pit. To enhance the waterproof effect of the Larsen steel sheet piles 3, the lock was caulked with fiber-rich cotton after injection. After the soil in the diversion channel 4 was excavated in layers and sections to the same elevation as the bottom of the large-diameter pressure-free pipeline, H-shaped steel with a size of HM250×250×9×14 was used as the purlin 10 between the Larsen steel sheet piles 3 on both sides of the diversion channel 4 and welded to the Larsen steel sheet piles 3. To control the stress and deformation of the steel sheet piles, DN200 steel pipe inner supports 11 were set between the purlins 10 on both sides of the steel sheet piles. The horizontal spacing of the inner supports 11 was 2.5m. A waterproof layer 7 is laid over the entire diversion channel 4, and the waterproof layer 7 is made of polyethylene colored strips; 100mmC20 concrete is poured on the bottom of the diversion channel 4 and the upper layer of the colored strips to seal the bottom, and 240mm thick solid bricks are used on both sides of the diversion channel 4 to build up to the top of the steel sheet piles, and the brick wall 9 is plastered with 20mm thick waterproof mortar. The brick wall 9 and the cushion surface concrete in the diversion channel 4 are well maintained to prevent cracking.

[0024] (3) According to the size of the cross section of the two newly built inspection wells 2 upstream and downstream, two steel cage break walls are made and welded. Sandbags are stacked layer by layer in the steel cage, and lifting lugs 15 are provided on the steel cage frame. The old pipes in the newly built inspection wells 2 upstream and downstream are removed, and the steel cage is lifted into the upstream and downstream inspection wells 2 by a car crane to seal the original flood discharge pipe opening between the two inspection wells 2 that needs to be updated, and the water flow in the pipe is introduced into the diversion channel 4. The diversion effect of the above-mentioned diversion channel 4 is closely monitored. When the diversion channel 4 has no deformation and leakage, and the original flood discharge rain and sewage pipe opening is tightly sealed and has no water seepage, the original large-diameter non-pressure pipe and the bottom plate and foundation foundation earthwork of the foundation pit can be excavated in layers and sections. The slope is sloped to the pit bottom elevation on both sides of the diversion channel 4. The slope surface 8 is protected with 100mm thick C20 shotcrete.

[0025] (4) Excavation is carried out on the original large-diameter non-pressure pipe section between the two inspection wells 2. If it affects the position of the foundation pit slope support, the excavation is carried out in layers and sections according to the requirements of the foundation pit slope support and earthwork excavation to a position 100mm below the elevation of the pipe bottom cushion surface. A 100mm thick C20 concrete cushion layer 6 is poured under the updated section of the old pipeline. The main structure of the box culvert 1 is cast in C30 concrete. The internal and external contour structural dimensions of the box culvert 1 meet the water flow requirements of the original pipeline.

[0026] (5) After the main structure of the box culvert 1 meets the functional requirements and has been inspected and accepted, the reinforced cage cut-off wall that blocks the original pipeline in the newly built inspection well 2 upstream and downstream is hoisted to the temporary diversion opening of the inspection well 2, and the diversion open channel 4 is cut off and blocked, and water is introduced into the newly built reinforced concrete box culvert 1. After the construction joint of the temporary opening is treated, a micro-expansion concrete with a strength one grade higher than that of the inspection well 2 is poured to seal it. After the sealing is completed, waterproofing construction is carried out on the inspection well 2 and the main body of the box culvert 1, and the side walls are backfilled and compacted in layers. After the backfill is completed, the steel sheet piles are removed and the remaining foundation and earthwork excavation in the foundation pit are started.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the scope of protection of the present invention.

Claims

1. A method for in-situ transformation of a non-pressure pipeline, characterized in that: The following steps are involved: S1. Determine the buried depth and direction of the non-pressure pipeline to be renovated, build reinforced concrete inspection wells in situ at both ends of the non-pressure pipeline in the foundation pit, and open a temporary diversion hole on the side of the inspection well perpendicular to the non-pressure pipeline; S2. Construct a new diversion channel in parallel with the pressure-free pipeline in the foundation pit. Use Larsen steel sheet piles on both sides of the diversion channel for support, and set perimeter purlins and internal supports between the Larsen steel sheet piles. S3. Lay a waterproof layer in the diversion channel and pour a concrete cushion on the waterproof layer. Build brick walls on both sides of the diversion channel and apply waterproof plastering treatment. S4. Set up a cutoff wall in the two inspection wells to block the original non-pressure pipe opening between the two inspection wells, and divert the water flow in the original non-pressure pipe into the diversion channel through the temporary diversion hole; S5. Excavate the original non-pressure pipeline section, remove the old pipeline, and build a new box culvert in the original location; S6. After the box culvert is accepted, the cut-off wall will be moved to the temporary diversion hole to cut off the flow, and the water flow will be introduced from the diversion open channel into the newly built box culvert, and the temporary diversion hole will be sealed to complete the in-situ transformation of the pressure-free pipeline.

2. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S1, the outer structure of the temporary diversion tunnel is pre-buried with Larsen steel sheet piles and water-stop steel plates; the Larsen steel sheet piles are driven into the soil layer at least 6m below, and the water-stop steel plates are overlapped and fully welded to the Larsen steel sheet piles.

3. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S2, the support structure of the diversion channel includes Larsen steel sheet piles, perimeter purlins and internal supports; the perimeter purlins are H-shaped steel and are welded and fixed to the Larsen steel sheet piles; the internal supports are steel pipes with a horizontal spacing of 2.5m.

4. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S3, the waterproof layer is polyethylene colored strip cloth; the thickness of the concrete cushion layer is 100 mm; the brick wall is a 240 mm thick solid brick wall, and the surface is plastered with waterproof mortar.

5. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: Step S5 includes: reserving a 1m wide slope on both sides of the diversion channel to the pit bottom elevation, using 100mm thick C20 shotcrete to protect the slope surface, then excavating the original non-pressure pipeline section, dismantling the old pipeline, and building a new box culvert in the original location.

6. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S4, the break wall includes a steel cage frame and sandbags. The steel cage frame is made of welded steel bars, and sandbags are stacked layer by layer inside. The steel cage frame is provided with lifting ears.

7. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S5, the box culvert is a cast-in-place reinforced concrete structure, and its outer contour size matches the flow requirement of the original non-pressure pipeline. The side walls, top plate and bottom plate of the box culvert are all subjected to haunch treatment.

8. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: In step S6, when sealing the temporary diversion hole, micro-expansive concrete is used for pouring, and the strength of the expansive concrete is at least one grade higher than that of the concrete of the inspection well.

9. The in-situ transformation method of a pressure-free pipeline according to claim 1, characterized in that: After step S6, the method further includes: excavating the remaining earthwork in the foundation pit after the construction of the diversion channel and the box culvert is completed.

10. The in-situ transformation method of a pressure-free pipeline according to any one of claims 1 to 9, characterized in that: The locking mouth of Larsen steel sheet pile is coated with grease, and fiber-rich cotton batting is used to caulk the seams after injection.

Images