A method for constructing a water-sealing conversion between old and new sewage main pipes crossing a deep foundation pit.

Abstract

A method for constructing a new sewage main pipe across a deep foundation pit, involving sealing and converting old and new pipes while maintaining water flow, solves the problem of long relocation and construction cycles that disrupt residents' lives. The method includes the following steps: S1, constructing and building a new sewage main pipe, connecting it to the existing inverted siphon upstream; S2, cutting the old pipe in the downstream well, breaking down the original pipe wall to create a passage between the old and new pipes, and connecting the upstream existing inverted siphon to the new well to allow for pressure-divided water flow; S3, sealing the upstream main pipe, and sealing the downstream existing well after the water flow in the old pipe decreases; S4, cutting and removing the old pipe, and putting the new pipe into use.

Description

Technical Field

[0001] This invention relates to the field of urban underground engineering construction technology, and in particular to a method for the construction of a water-sealing and conversion of old and new sewage main pipes crossing a deep foundation pit. Background Technology

[0002] Influenced by the global economic environment and domestic livelihood needs, the state has vigorously supported local governments in infrastructure construction. The vigorous development of infrastructure construction has promoted the improvement of construction standards. There are more and more municipal engineering projects involving people's livelihood. The current construction principle is to minimize the impact on residents around the project. In the construction of urban infrastructure, it is often necessary to relocate various pipelines, including sewage and tap water pipes. For the relocation of water pipelines such as sewage and tap water that involve people's livelihood, the water supply is often cut off and construction is carried out as soon as possible to shorten the construction time and reduce the impact on surrounding residents. However, the water supply cut-off period still has a certain impact on the production and life of surrounding residents.

[0003] In engineering construction, various pipelines often need to cross the foundation pit due to factors such as construction period, cost, and public welfare. In existing urban infrastructure construction, it is common to encounter situations where multiple pipelines, including sewage pipes, need to be relocated. Before constructing deep foundation pits in cities, pipelines that may affect the excavation are typically investigated and relocated in advance, especially water-bearing pipelines such as sewage, tap water, and reclaimed water that affect public welfare. This approach is feasible for projects with long construction periods, but it is disadvantageous for urban infrastructure projects with tight schedules. The relocation of pipelines increases construction time, which in turn prolongs the impact on the travel, production, and daily life of residents in the surrounding area. Summary of the Invention

[0004] In response to the above situation and to overcome the shortcomings of the existing technology, this invention provides a method for the construction of a new and old sewage main pipe crossing a deep foundation pit with water sealing and conversion, which effectively solves the problem of long relocation and reconstruction construction cycles that affect the lives of citizens.

[0005] To address the aforementioned issues, a method for constructing a water-sealing conversion between old and new sewage main pipes crossing deep foundation pits includes the following steps: S1, Construction of new main sewage pipe, and construction of a new well to connect to the existing inverted siphon well upstream; S2, cut the old pipe in the downstream well, break the original pipe wall in the well to realize the passage between the old and new pipes, and connect the original inverted siphon well and the new well to allow the flow of water pressure to be divided; S3. Block the upstream main pipe, and after the water flow in the old pipe decreases, block the downstream original well; S4, cut and remove the old pipe, and put the new pipe into use.

[0006] Preferably, step S1 includes the following steps: S11, laying out and marking the safety excavation boundary lines of the existing old pipeline and manhole, and using a combination of mechanical and manual excavation to ensure the stability of the existing old pipeline during the excavation process; S12, construct the new pipeline and well chamber according to the drawings, build the new well on the side of the original inverted siphon, set a long chute at the inlet of the new pipeline, chisel out a square hole between the original upstream inverted siphon and the new well chamber, and use a grinding wheel to grind to ensure that the inner wall of the hole is smooth and no sharp steel bar ends are exposed on the surface.

[0007] Preferably, step S2 includes cutting the old pipeline in the newly built working well, and the steps are as follows: S21, the top of the foundation pit where the pipe section is located is raised to the ground or a steel cylinder is used to raise it to the ground. Ventilation and deodorization equipment is brought in and installed and debugged. Toxic and harmful gas detection equipment and a sufficient number of gas masks are prepared on site. S22, preparation for cutover construction: The truck crane is parked next to the new well foundation pit, and the precast reinforced concrete cover plate on top is lifted off. After taking all protective measures, the operators go down into the well and put the hoisting wire rope on the sewage pipe section to be broken. S23, A cutting platform is built above the well site where the pipe is to be cut. The operators then install the diamond steel wire that passes through the bottom of the pipe and install the positioning pulley. S24. During the period of lowest water flow that day, after the operators put on protective work clothes and gas masks, they went down into the well to drill holes at the bottom of the pipe section to be broken to release water pressure and then cut and break the pipe section. S25, the crane lifts out the partially broken pipe section, cleans up the scattered concrete fragments of the pipe section at the bottom of the well, and after the personnel withdraw, the precast reinforced concrete cover plate is placed on the top of the well, and rubber waterstops are installed at the joints. If necessary, cement blocks can be placed on top of it.

[0008] Preferably, step S2 includes cutting the old pipes inside the original inverted siphon well, which is a repeat of steps S21 to S25.

[0009] This invention employs a construction method that involves first constructing a new pipeline, then sealing the old pipeline with water, and finally diverting the water flow to the new pipeline. This method improves safety and operability, and facilitates faster construction. It also reduces the impact on the lives and livelihoods of surrounding residents caused by pipeline relocation, saves construction time, and reduces project costs. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the first stage of the construction method of the present invention; Figure 2 This is a schematic diagram of the second stage of the construction method of the present invention; Figure 3 This is a schematic diagram of the third stage of the construction method of the present invention. Detailed Implementation

[0011] The present invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, illustrating only the basic structure of the invention in a schematic manner, and therefore only show the components relevant to the invention.

[0012] The inventor's project is located in the central urban area of ​​a city. The construction process is complex and time-consuming, and it has a significant impact on the lives of surrounding residents. This invention adopts a construction method that first constructs a new pipeline, then seals the old pipeline with water, and finally converts the water flow to the new pipeline. This method improves safety and operability, helps to speed up the construction progress, and can also reduce the impact on the production and lives of surrounding residents caused by pipeline relocation and reconstruction. It also saves construction time and project costs.

[0013] This construction is mainly divided into three stages. The first stage is the completion of the construction of new pipelines and inspection wells, and the existing old pipelines are allowed to flow and drain normally. The second stage is the flow diversion stage, where the existing pipelines and the new pipelines flow together, reducing the normal flow and drainage volume of the old pipelines and facilitating the sealing and cutting of the old pipelines. The third stage is the completion of the sealing and cutting of the existing old pipelines, and the new pipelines are allowed to flow and drain normally.

[0014] Construction process The process includes: positioning and excavation of the existing DN1500 sewage pipe → installation of the new DN1800 sewage pipe → cutting the existing old pipe with water in the newly built receiving and conversion working well (W28) → cutting the old pipe with water in the original inverted siphon well → sealing the upstream and downstream pipe ends of the old pipe → completing the sealing of the old pipe and allowing the new pipe to flow through its entire cross-section → finishing work.

[0015] Specific implementation methods Step 1: Locating, measuring, and excavating the existing DN1500 sewage pipe Based on the original municipal pipeline construction drawings and on-site inspection, professional surveyors laid out and marked the safety excavation boundaries of the existing old pipeline and manhole. Excavation was carried out using a combination of machinery and manual labor to ensure the stability of the existing old pipeline during the excavation process.

[0016] Step 2: Installation of the new DN1800 sewage pipe The construction of the new DN1800 pipeline (W25-W28) and manhole was completed according to the design drawings. A new manhole (manhole 1) was built on the side of the existing inverted siphon. The dimensions of manhole 1 are 2.8m × 1.5m, and the height is 2.5m. A 1m long chute was installed at the inlet of the new pipeline to facilitate the introduction of sewage. A 1.8x1.8 square hole was drilled between the upstream existing inverted siphon and the new manhole 1. The inner wall of the hole was smoothed using a grinder to ensure that no sharp rebar ends were exposed on the surface. Mortar was applied as needed.

[0017] Step 3: Cutting the existing old pipeline with water inside the newly built receiving and conversion working well (W28). The following method is used for cutting existing pipelines while they are submerged in water: A diamond wire saw is used for pipe cutting. The advantages of using a diamond wire saw are that it is noiseless, vibration-free, does not damage the structure, and produces clean cuts. Its cutting speed is 6 times that of disc cutters and 15 times that of pneumatic drills. Before cutting, a cutting platform is erected and placed above the pipeline to be cut. Then, a diamond wire saw is installed by passing it through the bottom of the pipe, followed by the installation of positioning pulleys. A truck crane is used to fix the platform in place during construction, which also facilitates lifting after cutting. Then, the entire pipeline is cut. Due to the pressure difference between the upstream and downstream sides of the old pipeline, the underwater cutting operation of the existing old pipeline in well W28 needs to be carried out according to the following steps: (1) The top of the foundation pit where the pipe section is located is raised to the ground level or a steel cylinder is used to raise it to the ground level. Ventilation and deodorization equipment is brought to the site and installed and commissioned. Toxic and harmful gas detection equipment and a sufficient number of gas masks are prepared on site.

[0018] (2) Preparation for cut-and-connection construction. The truck crane is parked next to the W28 well pit, and the precast reinforced concrete cover plate on top is lifted off. After taking all necessary protective measures, the operators go down into the well and attach the hoisting wire rope to the sewage pipe section to be broken.

[0019] (3) A cutting platform is built above the well site where the pipe is to be cut. The operators carry out the installation of the diamond steel wire through the bottom of the pipe and then install the positioning pulley.

[0020] (4) According to the minimum water flow time period (2:00-4:00 at night) provided by the municipal sewage management department, after the operators put on protective work clothes and gas masks, they go down into the well to drill holes at the bottom of the pipe section to be broken to release water and depressurize, and then cut and break the pipe section.

[0021] (5) The crane lifts out the partially broken pipe section and cleans up the scattered concrete fragments of the pipe section at the bottom of the well. After the personnel are evacuated, the precast reinforced concrete cover plate is placed on top of the well, and rubber waterstops are installed at the joints. If necessary, cement blocks can be placed on top of it to prevent the sewage pressure from the pressure well next to it from being washed away by the precast cover plate after water is supplied.

[0022] Step 4: Perform water-bearing cutting of the old pipes inside the original inverted siphon. When cutting the old pipeline, gas detection is first performed inside the manhole. A dedicated safety officer on site uses a multi-functional toxic gas detector to test the air inside the manhole to ensure safety. The crane first lifts the prefabricated top cover plate at the top of the pit, then cuts the existing sewage pipe section to a length of 3m, cutting it off in four cuts. The cut section is then lifted out and the prefabricated top cover plate is replaced. The specific construction method is the same as the method for cutting the existing old pipeline with water in the newly built receiving and conversion working manhole (W28) in the third step. At this time, the new pipe and the existing old pipe flow simultaneously.

[0023] Step 5: Seal the upstream and downstream pipe ends of the old pipeline (1) Anti-erosion measures during permanent sealing Permanent sealing and anti-erosion measures: During permanent sealing, considering the sewage transportation during the construction period, temporary anti-erosion measures are adopted in conjunction with permanent sealing. The upstream well of the permanent sealing is selected for the anti-erosion material, which is a prefabricated strip steel plate grid with support. After drilling holes in the well wall with an underwater pneumatic drilling machine, bolts are pre-embedded. Then, the strip steel plates are fixed to the well wall one by one with bolts. This can reduce the direct impact of water flow on the plug and ensure that the plug will not be impacted and collapsed by water flow before it is completely sealed, thereby achieving the effect of water-resistant sealing.

[0024] After the water flow in the sewage pipes decreases, divers wearing diving gear enter the well through the ventilation pipe via a prefabricated scaffolding passage. The divers maintain communication with the commander via wired walkie-talkies to understand the safety situation of the construction work inside the well. Using an underwater pneumatic drilling machine, the prefabricated strip steel plates are first drilled to fix their dimensions. After drilling in sequence, the plates are installed one by one, with adjacent plates spaced 10-20cm apart. After installation, they are fixed with template supports. This completes the anti-erosion measures before the water is sealed.

[0025] (2) Method for permanently sealing old DN1500 sewage pipes After the upstream anti-scour measures for the permanent sealing of this section were completed, diving equipment was used to enter and permanently seal the well via a connected scaffolding ladder. During sealing, debris at the sealing location was first removed, and the pipe wall was scrubbed (the main purpose being to ensure the plug adheres to the pipe wall and prevent leakage or movement). Then, the plug was sealed. Considering the permanent sealing, a 1500mm thick seal was used to ensure the plug's safety. During sealing, a hydrogen sulfide detector was used for monitoring inside the well. Divers were secured with safety ropes and harnesses inside the well, and a wired walkie-talkie was used above to communicate and understand the working conditions and safety situation inside the well. Permanent sealing was carried out only after all safety measures were in place.

[0026] Sealing Operation: 3-4 days before sealing, both manhole covers must be opened for ventilation, and air compressors must be used to blow air into the manhole. Sealing operations can only proceed after the sewage in the manhole and pipeline has been tested and found to be safe. Sealing operations must be carried out by divers wearing diving suits and JQ83 diving gear. A team of 3-4 people is required for sealing, with 1 person going down into the manhole and 2-3 people above. A lifeline must be secured to the person going down. The person above must maintain constant communication with the person down. If there is no response, the person above must be immediately pulled up using the lifeline. (It is crucial to avoid having the person below not respond before the person above goes down to check). (Equipment: QDS-7 radio / walkie-talkie and accessories, breathing apparatus, etc. Personal protective equipment: TF-12 ventilated heavy diving gear, lifeline, TF-12 diving helmet, TF-12 diving suit, TF diving shoes, thermal clothing, thermal socks, thermal hat).

[0027] Material transportation: Before the official sealing of the headworks, the materials required by the design will be transported to the designated location of the project. These materials include paving stones, yellow mud, cement, and wooden stakes.

[0028] Mixing clay: Clay is made by mixing yellow clay and ordinary silicate cement. In order to ensure the adhesion, strength and time required for the clay to reach the required strength, the following requirements are made for the clay in this project: A. No admixtures are added; B. No early strength agents are added; C. The ratio of yellow clay to cement is 2:1; D. The mixing must be uniform.

[0029] Foundation laying: After clearing obstacles and preparing materials, divers put on their gear and go underwater to lay the foundation. When laying the foundation, first apply a layer of clay to the bottom of the pipe, and then build the paving slabs on top of it. There must be 2-3 cm of clay between the paving slabs or between the paving slabs and the pipe wall.

[0030] Wall construction: Continue to build the wall on the prepared foundation, ensuring that the clay concrete is evenly spread to guarantee that the wall is hard and firm.

[0031] Pre-drilled holes: To mitigate the pressure and impact of water flow on the sealing wall, holes of appropriate diameter must be pre-drilled when sealing the pipe. One hole needs to be pre-drilled for each pipe, the size of which depends on the water flow rate. When placing the prefabricated pipe, the wall must be properly sealed with adhesive.

[0032] Pipeline sealing: On the basis of laying the foundation and reserving the holes, the pipeline is sealed by building a paving slab.

[0033] Closing: The quality of closure directly affects the success or failure of sealing the pipeline. When the paving slab reaches the top of the pipeline, a row of reverse rakes is nailed between the paving slab and the top of the pipeline. The nails are nailed repeatedly at intervals until they are firmly nailed. Then, clay is applied and stuffed between or on the reverse rakes.

[0034] Downstream sealing involves sealing the original well with sandbags and filling the gaps with mortar.

[0035] Step 6: After the water in the pipe is sealed, install the cover plates of the upstream and downstream wells, construct the well shaft, and backfill the soil.

[0036] The embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that various variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of this invention.

Claims

1. A method for constructing a water-sealing and conversion project between old and new sewage main pipes crossing a deep foundation pit, characterized in that... Includes the following steps: S1, Construction of new main sewage pipe, and construction of a new well to connect to the existing inverted siphon well upstream; S2, cut the old pipe in the downstream well, break the original pipe wall in the well to realize the passage between the old and new pipes, and connect the original inverted siphon well and the new well to allow the flow of water pressure to be divided; S3, the upstream main pipe is blocked, and after the water flow in the old pipe decreases, the downstream original well is blocked; S4, Cut and remove the old pipe, and put the new pipe into use; in: Step S1 includes the following steps: S11: Lay out and mark the safety excavation boundary lines of the existing old pipelines and manholes, and use a combination of mechanical and manual excavation to ensure the stability of the existing old pipelines during the excavation process; S12, construct the new pipeline and well chamber according to the drawings, build the new well on the side of the original inverted siphon, set a long chute at the inlet of the new pipeline, chisel out a square hole between the original upstream inverted siphon and the new well chamber, and use a grinding wheel to grind to ensure that the inner wall of the hole is smooth and no sharp steel bar ends are exposed on the surface. In step S3, anti-impact measures during permanent sealing: During permanent sealing, considering the sewage transport during construction, temporary anti-scouring measures are adopted to coordinate with permanent sealing. The sealing is carried out in the upstream well of the permanent sealing site. The anti-scouring material is a prefabricated strip steel plate grid with support. After drilling holes in the well wall with an underwater pneumatic drilling machine, bolts are pre-embedded. Then, the strip steel plates are fixed to the well wall one by one with bolts to reduce the direct impact of water flow on the plug and ensure that the plug will not be impacted and collapsed by water flow before it is completely sealed, thereby achieving the effect of water-resistant sealing.

2. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that, In the cutting operation, diamond wire saws are used for pipe cutting. Before cutting, first set up a cutting platform and place it above the pipe to be cut; Then, the diamond steel wire is installed by passing through the bottom of the well pipe, and then the positioning pulley is installed; A truck crane is used to secure the pipe during construction, and it also facilitates lifting after the pipe is cut. Then the entire pipe is cut.

3. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that... Step S2 includes cutting the old pipeline within the newly constructed working shaft, and the steps are as follows: S21, the top of the foundation pit where the pipe section is located is raised to the ground or a steel cylinder is used to raise it to the ground. Ventilation and deodorization equipment is brought in and installed and debugged. Toxic and harmful gas detection equipment and a sufficient number of gas masks are prepared on site. S22, preparation for cutover construction: The truck crane is parked next to the new well foundation pit, and the precast reinforced concrete cover plate on top is lifted off. After taking all protective measures, the operators go down into the well and put the hoisting wire rope on the sewage pipe section to be broken. S23, A cutting platform is built above the well site where the pipe is to be cut. The operators then install the diamond steel wire that passes through the bottom of the pipe and install the positioning pulley. S24. During the period of lowest water flow that day, after the operators put on protective work clothes and gas masks, they went down into the well to drill holes at the bottom of the pipe section to be broken to release water pressure and then cut and break the pipe section. S25, the crane lifts out the partially broken pipe section, cleans up the scattered concrete fragments of the pipe section at the bottom of the well, and after the personnel withdraw, the precast reinforced concrete cover plate is placed on top of the well, and rubber waterstops are installed at the joints. If necessary, cement blocks can be placed on top of it to prevent the sewage pressure from the pressure well next to it from being washed away by the precast cover plate after water is supplied.

4. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 3, characterized in that... Step S2 includes cutting the old pipes inside the original inverted siphon well, which is a repeat of steps S21 to S25.

5. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that, In step S3, during permanent sealing: After the water flow in the sewage pipes decreases, divers wearing diving gear enter the well through the ventilation pipe via a prefabricated scaffolding passage. The divers maintain communication with the commander via wired walkie-talkies to understand the safety situation of the construction work inside the well. Using an underwater pneumatic drilling machine, the prefabricated strip steel plates are first drilled to fix their dimensions. After drilling in sequence, the plates are installed one by one, with adjacent plates spaced 10-20cm apart. After installation, they are fixed with template supports. This completes the anti-erosion measures before the water is sealed.

6. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that, In step S3, the method for permanently sealing the DN1500 old sewage pipe is as follows: After the upstream anti-scouring measures for the permanent sealing of this section are completed, diving equipment is used to enter through the connected scaffolding ladder and perform permanent sealing. During sealing, the debris at the sealing location is first removed, the pipe wall is washed, and then the sealing is carried out. Considering that this plug is a permanent seal, a thickness of 1500mm is used to ensure the safety of the plug. During the sealing process, a hydrogen sulfide detector is used for monitoring inside the well. Divers are secured inside the well with safety ropes and harnesses, and communicate via wired walkie-talkies from above to understand the working conditions and safety situation inside the well. Once all safety measures are in place, the well is permanently sealed.

7. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that, In step S3, the sealing process is carried out: Three to four days before sealing, both manhole covers must be opened for ventilation, and an air compressor must be used to blow air into the manhole. Sealing can only be carried out after the sewage in the manhole and pipeline has been tested and found to be safe. The sealing operation was carried out by "water ghosts" who put on diving suits and JQ83 diving equipment and went down into the well to carry out the work. When sealing the well, 3 to 4 people should be on standby, including 1 person working down the well and 2 to 3 people above. The person working down the well should be secured with a lifeline. The person above should maintain communication with the person working down the well. If there is no response, the person should be pulled up from the well immediately with the lifeline.

8. The method for constructing a water-sealing and conversion project of a new and old sewage main pipe crossing a deep foundation pit according to claim 1, characterized in that, Also includes: Transportation of materials: Before the official sealing of the headworks, the materials required by the design will be transported to the designated location of the project. These materials include paving stones, yellow mud, cement, and wooden stakes. Mixing of clay: Clay is made by mixing yellow clay and ordinary Portland cement. In order to ensure the adhesion, strength and time required for the clay to reach the required strength, the following requirements are made for the clay in this project: A. No admixtures are added; B. No early strength agents are added; C. The ratio of yellow clay to cement is 2:1; D. The mixing must be uniform. Foundation laying: After clearing obstacles and preparing materials, divers put on their gear and go underwater to lay the foundation; when laying the foundation, first apply a layer of clay to the bottom of the pipe, and then build the paving slab on it. There must be 2 to 3 cm of clay between the paving slabs or between the paving slab and the pipe wall. Wall construction: Continue to build the wall on the prepared foundation, ensuring that the clay concrete is evenly spread to guarantee that the wall is hard and solid; Pre-reserved holes: To mitigate the pressure and impact of water flow on the sealing wall, holes of appropriate diameter must be reserved when sealing the end. One hole needs to be reserved for sealing the pipe, and the size of the reserved pipe is determined according to the water flow rate. When placing the prefabricated pipe, the pipe wall must be properly sealed with adhesive. Pipe sealing: On the basis of laying the foundation and reserving the holes, the paving slab is built to seal the pipeline; Closing: The quality of closure directly affects the success or failure of sealing the pipeline. When the paving slab reaches the top of the pipeline, a row of reverse rake tips is nailed between the paving slab and the top of the pipeline. The nails are nailed repeatedly at intervals until they are firmly nailed. Then, clay and mortar are applied and stuffed between or on the reverse rake tips. Downstream sealing involves sealing the original well with sandbags and filling the gaps with mortar.

9. A method for constructing a water-sealing conversion between old and new sewage main pipes crossing a deep foundation pit, as described in claim 1, characterized in that... In step S4, when the old pipe is cut off: First, gas detection is carried out in the well chamber. The on-site safety officer uses a multi-functional toxic gas detector to detect the air in the well to ensure safety. The crane lifts the prefabricated top cover plate at the top of the foundation pit in advance, cuts the original sewage pipe section, the cutting length is 3m, and the pipe is cut off in 4 cuts. Then the cut part is lifted out and the prefabricated top cover plate is covered.

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