Construction method for continuous water relocation and transformation in new and old bilge wells

Abstract

The invention provides a construction method for continuous water relocation and transformation in new and old bilge wells, and relates to the field of relocation and transformation in bilge wells. The method comprises the following steps: step 1, investigating the existing in-well tangent change working condition, and investigating whether a launder, a running water level, a flow rate, a flow velocity and a surrounding environment exist or not; and 2, judging whether the existing well has the launder or not, and distinguishing into a cutting construction method with the launder in the existing well and a cutting construction method without the launder in the existing well. By the adoption of the method, switching of the new pipeline and the old pipeline is completed under the condition that operation of an existing drainage system is not affected, the method adapts to the working conditions that the flow rate is high, the flow speed is high, the water level is high, and whether an existing well contains a launder or not, diving operation is avoided, and it is ensured that water cutting and changing construction is conducted more safely and more efficiently in the existing sewage well without water interruption.

Description

Technical Field

[0001] This invention relates to the field of relocation and modification of sewage wells, specifically a construction method for relocating and modifying old and new sewage wells without interrupting water supply. Background Technology

[0002] With the acceleration of urbanization and the ever-expanding scale of urban construction, urban drainage systems can no longer meet the needs of urban development. Therefore, there is an urgent need to renovate existing municipal drainage networks to improve the quality of the urban water environment. New sewage pipelines often require connection to existing sewage pipelines through relocation construction, which has always been a major challenge in municipal pipeline construction. Relocation projects often result in the existing drainage system operating at reduced standards or the need for temporary drainage measures, significantly impacting the surrounding environment. Therefore, research on safe and reliable methods for relocating sewage trunk lines without interrupting water flow is increasing.

[0003] For example, CN114150749A discloses a construction method for connecting old and new sewage wells without interrupting water supply. In this method, a steel cofferdam is installed in the existing well, and concrete is poured inside the steel cofferdam. The steel cofferdam and the concrete form a double-structure rigid self-waterproofing system. After the new pipeline is connected, the steel cofferdam and the concrete are removed.

[0004] Its disadvantages are: ① For wells with flow channels, the above-mentioned method of continuous water supply in wells requires that the existing sewage well has a flat bottom and no flow channel; often, existing wells are designed with plain concrete flow channels to ensure smooth water flow, so the above-mentioned method of continuous water supply in wells is not applicable. ② For wells without flow channels, the steel cofferdam installation method of continuous water supply in wells does not consider the impact of water flow on the steel cofferdam; there are no effective connection measures between the steel cofferdam and the well wall, and concrete pouring will cause the steel cofferdam to shift; the subsequent demolition of concrete and steel cofferdam is difficult and risky; the construction and demolition of concrete result in resource waste.

[0005] Therefore, how to adapt to the working conditions of high flow rate, high flow velocity, high water level, and whether the existing well contains a flow channel for the construction method of relocating existing sewage wells without interrupting water flow has become an urgent problem to be studied and solved. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a method for relocating existing and new sewage wells without interrupting water flow, which solves the problem that the aforementioned methods for relocation without interrupting water flow are not applicable to wells with smooth water flow and designed plain concrete channels.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for relocating old and new sewage wells without interrupting water supply, comprising the following steps:

[0010] Step 1: Investigate the existing well cutting conditions, including whether there is a flow channel, operating water level, flow rate, flow velocity, and surrounding environment;

[0011] Step 2: Based on whether there is a flow channel in the existing well, the construction method for cutting and modifying the existing well is divided into two categories: construction method for cutting and modifying the existing well with a flow channel and construction method for cutting and modifying the existing well without a flow channel.

[0012] Step 3: When there is no flow channel in the existing well, steel cofferdams are used for design, fabrication, assembly, and installation; when there is a flow channel in the existing well, steel flow channels are used for design, fabrication, assembly, and installation.

[0013] Step 4: Cut the existing well top plate during construction, and then restore it. The cutting and modification are then complete.

[0014] Preferably, a method for relocating existing and new sewage wells without interrupting water flow includes the following steps:

[0015] Step 1: Before construction, prepare the steel cofferdam, guide rails and guide beams, internal supports, water-stopping devices, auxiliary installation devices and connectors;

[0016] Step 2: Make a hole in the top plate of the existing well, and then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam. Use a wire saw to cut it, and lift it out in sections according to the size of the lifting equipment.

[0017] Step 3: Steel cofferdam installation. After marking the positioning lines on the wall, a suspended basket is first lowered into the well. Expansion bolts are used to secure the guide rails from top to bottom. Then, a hand-operated hoist is installed. The steel cofferdam is then hoisted down into the well as a whole using a truck crane. During the lowering process, the hand-operated hoist is tightened while lowering to ensure the steel cofferdam is flush against the well wall. After the steel cofferdam is in place, workers secure the inner fixing bolts of the part above the water surface and pump water to check for leaks. Depending on the leakage situation, other water-stopping measures are implemented.

[0018] Step 4: Demolish the existing well wall, use a steel ladder to lower the new well, use a mobile frame to drill holes in the well wall and thread ropes and install guide wheels, then cut the concrete at the opening into multiple pieces according to the lifting equipment, pull them out by hand chain hoist and hoist them out by guide wheels, and then perform anti-corrosion treatment on the cut surfaces.

[0019] Step 5: Steel cofferdam dismantling. After anti-corrosion treatment, first remove the fixing bolts on both sides from bottom to top, loosen the hand chain hoist, lift out the steel cofferdam, and use a suspended basket to dismantle the steel guide rails.

[0020] Preferably, the steel cofferdam is designed in an arc shape according to the high-speed water flow conditions of the existing well; the steel cofferdam is equipped with stiffening plates and steel supports inside.

[0021] Preferably, the water-stopping device is a three-layer water-stopping measure, wherein the outer and bottom are provided with P-type rubber water-stopping strips, the inner side is a steel plate and a flat rubber plate, and the middle is a space filled with cotton wool; the auxiliary installation device is a hand-operated hoist installed between the steel cofferdam and the well wall.

[0022] Preferably, a method for relocating existing and new sewage wells without interrupting water flow includes the following steps:

[0023] Step 1: Before construction, prepare the steel flow channel, limiting beam, internal support, water-stopping device, fasteners, and work safety measures;

[0024] Step 2: Open a hole in the existing well top plate, then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam, cut it with a wire saw, and lift it out in sections according to the size of the lifting equipment;

[0025] Step 3: Before installation, install the downstream steel flow channel limiting beam. Fix it to the existing plain concrete flow channel of the well with expansion bolts. Then, use lifting equipment to hoist the entire steel flow channel into the well. First, pre-install the steel flow channel, then correct the steel flow channel, and finally complete the lowering.

[0026] Step 4: The existing concrete channel of the well is demolished in one stage. A part of the existing channel is retained on the side of the steel channel. It is chiseled at an angle to ensure the stability of the working surface.

[0027] Step 5: Demolish the existing well wall, use a steel ladder to lower the new well, use a mobile frame to drill holes in the well wall and install ropes and guide wheels, cut the concrete at the opening into multiple pieces according to the lifting equipment, pull them out by hand chain hoists, and then perform anti-corrosion treatment on the cut surfaces.

[0028] Step Six: Two-stage demolition of the existing concrete flow channel. The remaining portion of the existing flow channel will be removed using two pneumatic picks, and the excavated soil will be hoisted out using a hopper.

[0029] Step 7: Next, the steel flow channel is dismantled. Workers wearing safety belts and gas masks loosen the fixing bolts of the steel flow channel and release water from one side to balance the water level on both sides. Taking into account the weight of the water, a large-scale lifting and hoisting equipment is used to lift the steel flow channel out.

[0030] Preferably, the steel flow channel is designed according to the shape of the existing plain concrete flow channel; the limiting beam is made of steel and is fixed to the existing plain concrete flow channel with expansion bolts.

[0031] Preferably, a steel support is provided inside the steel flow channel; a fixed steel plate is provided on the steel flow channel and fixed with expansion bolts.

[0032] (III) Beneficial Effects

[0033] This invention provides a method for relocating old and new sewage wells without interrupting water supply. It offers the following advantages:

[0034] 1. By adopting this method, the switch between old and new pipelines can be completed without affecting the operation of the existing drainage system.

[0035] 2. This method is suitable for working conditions with high flow rate, high flow velocity, high water level, and whether the existing well contains a flow channel.

[0036] 3. By adopting this method, diving operations are avoided, ensuring that the existing sewage well can be renovated and cut off more safely and efficiently without interrupting water supply. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the construction process for a method of relocating old and new sewage wells without interrupting water supply, as proposed in this invention.

[0038] Figure 2 This is a schematic diagram of the installation of a channelless steel cofferdam for a new method of relocating old and new sewage wells without interrupting water flow, as proposed in this invention.

[0039] Figure 3 For the present invention Figure 2 Enlarged view of section A in the middle;

[0040] Figure 4 This is a schematic diagram of the installation of a steel trough in a troughed well, which is part of a construction method for relocating old and new sewage wells without interrupting water supply, as proposed in this invention.

[0041] Figure 5 This invention proposes a method for relocating and modifying old and new sewage wells without interrupting water supply. Figure 4 Schematic diagram of the one-stage demolition of the existing plain concrete flow channel in the flow channel well;

[0042] Figure 6 This is a schematic diagram of the cutting of the existing well wall in a new method for relocating old and new sewage wells without interrupting water supply, as proposed in this invention.

[0043] Figure 7 This is a schematic diagram of the two-stage demolition of the existing plain concrete channel of the channeled well, which is part of the construction method for relocating and modifying old and new sewage wells without interrupting water flow, as proposed in this invention.

[0044] Figure 8 This is a schematic diagram illustrating the dismantling of existing plain concrete or steel flow channels in a channeled well, part of a construction method for relocating old and new sewage wells without interrupting water supply, as proposed in this invention.

[0045] in,

[0046] 11. Hand-operated hoist; 12. Existing well; 13. New well; 14. Steel cofferdam; 15. Expansion bolt; 16. P-type rubber strip; 17. Flat rubber sheet; 18. Steel cofferdam guide rail; 19. Pipeline;

[0047] 21. Groove fixing steel plate; 22. Groove supporting channel steel; 23. Plain concrete flow channel; 24. High-density sponge; 25. Steel flow channel; 26. U-shaped guide channel support ring; 27. Sealing and water-stopping ring; 28. Downstream steel flow channel limiting beam. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1:

[0050] like Figure 1-7 As shown in the figure, this invention provides a method for relocating old and new sewage wells without interrupting water supply. The technical solution is as follows:

[0051] Step 1: Investigate the existing well cutting conditions, including whether there is a flow channel, operating water level, flow rate, flow velocity, and surrounding environment.

[0052] Step 2: Based on whether there is a flow channel in the existing well, the construction method for cutting and modifying the existing well with a flow channel is divided into two methods: the construction method for cutting and modifying the existing well without a flow channel.

[0053] Step 3

[0054] For existing wells without flow channels, the following construction methods are used:

[0055] 1. Steel cofferdam design, fabrication, and assembly: The main structure of the steel cofferdam is made of Q235 steel and consists of six parts: the steel cofferdam itself, guide rails and guide beams, internal supports, water-stopping devices, auxiliary installation devices, and connectors. The steel cofferdam is designed in an arc shape to reduce resistance to the existing well's flow, minimizing the impact on the existing sewage system during the relocation process; it also improves the stability and water-stopping effect under stress. The thickness of the steel cofferdam needs to be confirmed through numerical simulation based on the working conditions. During implementation, it can be assembled on-site in multiple sections according to the water level and transportation conditions, using bolt connections and internal water-stopping rubber. To prevent deformation during processing, transportation, and installation, and to ensure stability under stress after lowering, reinforcing plates (10mm thick, 600mm spacing, B=10mm) and steel supports (No. 14 channel steel and No. 10 channel steel supports, spaced no more than 3m apart) are installed inside the steel cofferdam. To address the issue of installation displacement caused by the impact of high-speed water flow within the existing well on the steel cofferdam during its lowering process, steel Q235 guide rails were installed on the existing well wall before lowering and installing the steel cofferdam. The guide rails and guide beams needed to fulfill both the limiting function and the water-stopping function. The guide rails were installed above the water surface and fixed using M16*150@300. To prevent deformation during the processing, transportation, and installation of the steel cofferdam and to ensure its stability under stress after lowering, reinforcing plates (10mm thick, 600mm spacing, B=10mm) and steel supports (No. 14 channel steel and No. 10 channel steel supports, spaced no more than 3m apart) were installed inside the steel cofferdam. To cope with uneven well walls, the steel cofferdam was equipped with three water-stopping measures: a 5cm high P-type rubber waterstop strip on the outer side and bottom, an 8mm steel plate and a 2cm thick flat rubber plate on the inner side, and a space filled with cotton wool in the middle. If the outer side failed and leakage occurred, the cotton wool filling in the middle would provide initial water stoppage, and finally, after pumping out the water, the inner flat rubber plate would be used for further water stoppage. During the lowering and installation of the steel cofferdam, an auxiliary installation device was set up between the steel cofferdam and the well wall to ensure that the steel cofferdam was tightly attached to the well wall. A hand-operated hoist was used to lower the steel cofferdam while simultaneously tightening the hoist to ensure a tight fit. The inner side of the steel cofferdam uses an 8mm steel plate and a 2cm thick flat rubber sheet, which serves both as a water-stopping function and to further secure the steel cofferdam. The 8mm steel plate is fixed to the bottom of the steel cofferdam using M16*150@300 steel. After the cofferdam is installed and the outer and middle sides are sealed with water, the water level inside the cofferdam is further lowered by pumping water while the bolts are being tightened.

[0056] 2. Open a hole in the existing well top plate, and then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam. Use a wire saw to cut it, and lift it out in sections according to the size of the lifting equipment.

[0057] 3. Steel cofferdam installation: After marking the positioning lines on the wall, a suspended basket is first lowered into the well. Expansion bolts (M16*150@300) are used to fix the guide rails from top to bottom, followed by the installation of a hand-operated hoist. Then, the entire steel cofferdam guide rail is hoisted into the well using a truck crane. During lowering, the hand-operated hoist is tightened while lowering to ensure the steel cofferdam is flush against the well wall. After the steel cofferdam is in place, workers fix the inner fixing bolts (M16*150@300) above the water surface. Water is pumped out to check for leaks. If the outer sealing fails and leakage is severe, cotton wadding is used for initial sealing. Finally, water is pumped out again, and the inner flat rubber plate is used for further sealing. After the water level has been pumped down, workers enter the steel cofferdam and fix 8mm steel plates (M16*150@300) from top to bottom of the cofferdam.

[0058] 4. The existing well wall was demolished, and a steel ladder was used to lower a new well. A mobile frame was used for drilling holes in the well wall, threading ropes, and installing guide wheels. 20mm holes were drilled using an electric drill for rope threading. The rope saw was installed on the top plate of the well. The concrete at the opening was cut into multiple pieces using a lifting device, which were then pulled out and hoisted out by a hand-operated hoist. The cut surfaces were then treated with anti-corrosion coating.

[0059] 5. After the steel cofferdam is dismantled and the anti-corrosion treatment is completed, first remove the fixing bolts on both sides from bottom to top, loosen the hand chain hoist, lift out the steel cofferdam, and use a basket to dismantle the steel guide rail.

[0060] For existing wells with flow channels, the following construction methods are used:

[0061] 1. Steel trough design, fabrication, and assembly: The main structure of the steel trough is made of Q235 steel and consists of seven parts: the steel trough itself, a limiting beam, internal supports, a water-stopping device, fasteners, and operational safety measures. The steel trough is designed to fit the shape of the existing well's concrete trough, minimizing resistance to the existing water flow and ensuring minimal impact on the existing sewage system during the relocation process. This also improves the stability and water-stopping effect of the steel trough under stress. The thickness of the steel trough needs to be confirmed through numerical simulation based on the working conditions. During implementation, the trough can be assembled in multiple sections on-site, using bolt connections and internal water-stopping rubber, depending on the water level and transportation conditions. To address the issue of installation displacement caused by the impact of high-speed water flow in the existing well during the lowering process, a Q235 steel limiting beam is installed downstream of the existing well's concrete trough before installation, and is fixed to the existing well's concrete trough using expansion bolts. To prevent deformation during the processing, transportation, and installation of the steel trough, and to ensure its stability under stress after lowering, steel supports (No. 14 channel steel, spaced no more than 1.5m apart) are installed inside the steel trough. To address the unevenness of the existing concrete trough, the steel trough is 10cm smaller on each side than the existing trough. Water-stopping measures are implemented at both ends of the steel trough: sealing rings, δ20, B=50mm, with a 150mm thick high-density sponge pad for sealing inside; the thickness is adjusted on-site according to actual conditions. After lowering the steel trough, to prevent water flow from disturbing the waterstop, it is further secured by δ20 steel plates at 1m intervals, fixed with expansion bolts. These plates are 10cm higher than the top of the existing concrete trough to address its unevenness. After installation, steel scaffolding is laid on top of the steel trough for protection, preventing workers from falling into the water.

[0062] 2. Open a hole in the existing well top plate, and then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam. Use a wire saw to cut it, and lift it out in sections according to the size of the lifting equipment.

[0063] 3. Steel trough installation: Before installation, the downstream steel trough limiting beam is installed and fixed to the existing plain concrete trough in the well using expansion bolts to prevent water flow impact during descent. Then, the entire steel trough is hoisted into the well using lifting equipment. The steel trough is pre-installed and then adjusted. Finally, it is lowered into the well. Water pressure should be considered during hoisting, and the lifting capacity of the hoisting equipment should be maximized. After the steel trough is lowered, to prevent water flow impact and disturbance to the waterstop, it is further secured by fixing the two side steel plates to the top of the plain concrete trough. Workers are equipped with safety belts and gas masks and secured using expansion bolts. After securing, steel scaffolding is laid on top for protection to prevent workers from falling into the water.

[0064] 4. The existing concrete channel of the well will be demolished in one stage. A portion of the existing channel will be preserved on the side closest to the steel channel. The thickness will be calculated based on water pressure and its own stability to prevent sewage leakage and collapse, further protecting the work area. Except for the reserved portion, two pneumatic picks will be used to chisel away the channel to prevent electric shock and disturbance to the existing well. Excavated soil will be removed using a hopper. Chiseling will be done at an angle to ensure the stability of the working surface.

[0065] 5. The existing well wall was demolished, and a steel ladder was used to lower a new well. A mobile frame was used for drilling holes in the well wall, threading ropes, and installing guide wheels. 20mm holes were drilled for rope threading. The rope saw was installed on the top plate of the well. The concrete at the opening was cut into multiple pieces using lifting equipment, and then pulled out and hoisted out by a hand-operated hoist. The cut surfaces were then treated with anti-corrosion coating.

[0066] 6. The existing concrete channel of the well will be demolished in two stages. The remaining portion of the existing channel will be removed using two pneumatic drills, with the excavated soil lifted out using a hopper. A water pump will be used for emergency water removal during the demolition process, with one pump on standby. Workers will wear diving suits while chiseling to prevent drowning and poisoning. A designated person will supervise the work area during the operation. Excavated concrete debris should be promptly removed. The steel channel can only be dismantled after all demolition is completed and all personnel have left the work area.

[0067] 7. For the dismantling of the steel flow channel, workers wearing safety belts and gas masks should loosen the fixing bolts of the steel flow channel and release water from one side until the water levels on both sides are balanced. Taking into account the weight of the water, large-scale lifting equipment should be used to lift the steel flow channel out.

[0068] Step 4: Complete the restoration of the existing well top plate, and the cutting and modification are completed.

[0069] Example 2:

[0070] This embodiment is based on Embodiment 1:

[0071] The example illustrates a sewage main pipeline relocation project. Due to a conflict between the original sewage pipeline and the proposed river channel elevation, and given the existing sewage pumping station's capacity of 850,000 m³ / d, the relocation of the main sewage pipeline must not disrupt the existing pipeline's operation. Therefore, a continuous water supply relocation of the original sewage system is required. There are two relocation points: one is the WB1 well at the pumping station's outlet. This well has two inlet pipes: d3000 with a flow velocity of 0.9 m / s and d1600 with a flow velocity of 1.6 m / s. The WB1 well outlet pipe is d3200 with a flow velocity of 1.87 m / s. This well has a flat bottom, high flow rate, high velocity, and a water level as high as 3.4 m. One of the main pipelines is WB5 well, which has an inlet and outlet pipe of d3200 and a flow velocity of 1.87m / s. The well is designed with plain concrete, with a height of 3.2m and a 90-degree arc to change the direction of water flow. The normal operating water level in the well is 2.4m. This well has a plain concrete flow channel, a large flow rate, a high flow velocity, and a water level as high as 2.4m.

[0072] Step 1

[0073] For existing well WB1, the construction method for cutting and modifying the well without a flow channel is as follows:

[0074] 1. The design, fabrication, and assembly of the steel cofferdam are based on the existing well conditions, well size, two inlets and one outlet, large flow rate and high velocity. The steel cofferdam is made of Q235 steel, designed in an arc shape with a radius of 2250mm and an arc length of 5433mm. The thickness of the steel cofferdam needs to be confirmed through numerical simulation based on the working conditions and is ultimately determined to be 20mm. The height of the steel cofferdam is determined to be 5m based on the current well water depth of 3.4m. During implementation, according to the steel plate size and transportation conditions, it can be divided into 3 pieces (0.6m + 2.2m + 2.2m) and assembled on site using bolt connections, with an internal 20mm thick flat water-stop rubber. First, a steel guide rail, made of Q235 steel and 7.303m long, is installed above the liquid level in well WB1, and fixed to the existing well wall using M16*150@300 expansion bolts. The construction personnel complete the installation inside the suspended platform. To prevent deformation during the processing, transportation, and installation of the steel cofferdam, and to ensure its stability under stress after lowering, reinforcing plates (10mm thick, 600mm spacing, B=10mm) and steel supports (No. 14 channel steel and No. 10 channel steel supports, a total of three layers) are installed inside the steel cofferdam. To address uneven well walls, the steel cofferdam is equipped with three water-stopping measures: a 5cm high P-type rubber waterstop strip on the outer side and bottom, an 8mm steel plate and a 2cm thick flat rubber plate on the inner side, and a space filled with cotton wool in the middle. If the outer side fails and leaks, the cotton wool filling in the middle provides initial water stoppage, and finally, after pumping out the water, the inner flat rubber plate is used for further water stoppage. During the lowering and installation process, to ensure the steel cofferdam fits tightly against the well wall, an auxiliary installation device is installed between the steel cofferdam and the well wall: two 5t hand-operated hoists. The hand-operated hoists are tightened while the steel cofferdam is lowered to ensure it fits snugly against the well wall. The inner side of the steel cofferdam is made of 8mm steel plate and 2cm thick flat rubber, which serves two purposes: water-stopping and further fixing the steel cofferdam. The 8mm steel plate is fixed to the bottom of the steel cofferdam by M16*150@300. After the cofferdam is installed and the outer and middle sides are water-stopped, the water level inside the cofferdam is further lowered by pumping water while the bolts are fixed.

[0075] 2. Due to the construction requirements of the steel cofferdam inside well WB1, an opening needs to be made in the top slab of well WB1. The opening is 2m x 5m, to be cut into 3 sections, with the largest section having an area of ​​3.4m². The top slab is 250mm thick and weighs 2.2t. A 200mm diameter water drill will be used for drilling, a diamond rope chainsaw for cutting, and a 35t truck crane for hoisting. A long, hook-shaped pole (made of bamboo) will be used to hook through the hole.

[0076] 3. Steel cofferdam installation: After marking the wall positioning, a suspended basket is first lowered into the well. Expansion bolts (M16*150@300) are used to secure the guide rails from top to bottom, followed by the installation of two 5t hand-operated hoists. The entire steel cofferdam, weighing 5t, is then hoisted down into the well using a 35t truck crane. During lowering, the hand-operated hoists are tightened to ensure the cofferdam is flush against the well wall. After the cofferdam is in place, workers secure the inner side of the above-water portion with M16*150@300 bolts. Pumping inspection revealed uneven well walls and severe leakage due to ineffective outer sealing. Initial sealing was achieved by filling the middle with cotton wadding, followed by further sealing with inner flat rubber plates after pumping. Once the water level has been pumped down, workers enter the steel cofferdam and secure 8mm steel plates (M16*150@300) from top to bottom.

[0077] 4. The existing well wall was demolished, and a steel ladder was used to descend into the well. A mobile frame was used for drilling holes in the well wall, threading ropes, and installing guide wheels. 20mm holes were drilled using an electric drill for rope threading. The rope sawing equipment was set on the top plate of the well. The 2900×2900mm concrete opening was cut into 6 pieces, each weighing 2.2t, and lifted out using a 35t truck crane. The cut surfaces were treated with anti-corrosion coating.

[0078] 5. After the steel cofferdam is dismantled and the anti-corrosion treatment is completed, first remove the fixing bolts on both sides from bottom to top, loosen the hand chain hoist, lift out the steel cofferdam, and use a basket to dismantle the steel guide rail.

[0079] For existing wells with flow channels, the following construction methods are used:

[0080] 1. Steel trough design, fabrication, and assembly: Based on the existing well conditions, including the dimensions of the existing plain concrete trough, the width to be modified, and the large inflow and outflow rates and velocities, the steel trough is made of Q235 steel and designed to conform to the shape of the existing plain concrete trough. The outer radius is 7580mm, and the inner radius is 4600mm. The length of the steel trough extends by 1m on each side of the demolition area, resulting in a total demolition area of ​​3.2m and a steel trough length of approximately 5.2m. The thickness of the steel trough needs to be confirmed through numerical simulation based on the working conditions and is ultimately determined to be 20mm. The height of the steel trough is determined to be 3.3m based on the existing plain concrete trough height of 3.2m. During implementation, the steel plates are divided into three pieces and assembled on-site according to the dimensions and transportation conditions, using bolt connections and incorporating 20mm thick flat rubber seals. First, a steel limiting beam, made of Q235 steel and 4.2m long, is installed downstream of the existing plain concrete channel in Well WB5. It extends 50cm beyond the channel on each side and is fixed to the existing plain concrete channel using 6*M16*150 expansion bolts. To prevent deformation during processing, transportation, and installation, and to ensure stability under stress after lowering, steel supports (No. 14 channel steel, 5 in total, spaced 1.3m apart) are installed inside the steel channel. To address the unevenness of the existing plain concrete channel, the steel channel is 10cm smaller on each side than the existing channel. A water-stopping measure is installed at both ends of the steel channel: a sealing ring with a diameter of δ20 and a thickness of B=50mm, sealed internally with a 150mm thick high-density sponge pad. After the steel trough is lowered, to prevent water flow from impacting and disturbing the waterstop, it is further secured. δ20 steel plates are installed at the trough opening, spaced 1m apart, and fixed with 2*M16*250 expansion bolts. The plates are 10cm higher than the top of the existing plain concrete trough to compensate for unevenness. After installation, steel scaffolding boards are laid on top of the steel trough for protection, preventing workers from falling into the water.

[0081] 2. An opening needs to be made in the top slab of the existing well. Due to the large area required for the installation of the steel flow channel inside well WB5, the opening will be done in sections. Each section will first have a lifting hole drilled, and then the surrounding area will be cut. During the section cutting process, a 35t crane will be used to pre-lift the concrete slab sections (each section at the opening will not exceed 5t), and steel wire ropes will be threaded through the lifting holes. A φ100 water drill will be used to drill chainsaw holes in each concrete section, and a φ200 water drill will be used to drill the lifting holes.

[0082] 3. Steel trough installation: Before installation, a steel limiting beam, made of Q235 steel and 4.2m long, extending 50cm beyond the existing concrete trough in well WB5, is installed downstream. It is fixed to the existing concrete trough using 6*M16*150 expansion bolts to prevent water flow impact during lowering. The steel trough is then pre-installed and adjusted. Finally, it is hoisted and lowered. The total weight of the steel trough is 5t; considering water pressure, a 100t truck crane is used for hoisting. After lowering, to prevent water flow impact and disturbance to the waterstop, it is further secured. The steel trough is 3.2m high, 10cm above the existing trough opening, and bolted to the original trough at both ends. Workers wearing safety belts and gas masks use expansion bolts for securing the trough. After securing, steel scaffolding is laid on top for protection to prevent workers from falling into the water.

[0083] 4. The existing concrete channel of the well will be demolished in one stage. A 70cm section of the existing channel will be preserved on the side closest to the steel channel to prevent sewage leakage and collapse, further protecting the work area. Except for the reserved section, two pneumatic drills will be used to remove the channel. This is to prevent electric shock and disturbance to the existing well. Excavated soil will be removed using a hopper. The removal will be done at an angle to ensure the stability of the working surface.

[0084] 5. The existing well wall was demolished, and a steel ladder was used to lower the new well. A mobile frame was used for drilling holes in the well wall, threading ropes, and installing guide wheels. 20mm holes were drilled using an electric drill for rope threading. The 2900×2900mm concrete opening was cut into 6 pieces, each weighing 2.55t, and lifted out using a 35t truck crane. Finally, the cut surfaces were treated with anti-corrosion coating.

[0085] 6. The existing concrete channel of the well will be demolished in two stages. A 70cm section of the existing channel will remain, and two pneumatic drills will be used for chiseling. Excavated material will be removed using a hopper. A water pump will be used for emergency water pumping during the demolition process, with one pump on standby. Workers will wear diving suits while chiseling to prevent drowning and poisoning. A designated person will supervise the work area during the operation. Excavated concrete debris should be promptly removed. The steel channel can only be dismantled after all chiseling is completed and all personnel have left the work area.

[0086] 7. For the dismantling of the steel trough, workers wearing safety belts and gas masks should loosen the fixing bolts of the steel trough and release water from one side until the water levels on both sides are balanced. Taking into account the weight of the water, a 220t truck crane should be used to dismantle and lift out the steel trough.

[0087] Step 2: Complete the restoration of the existing well top plate, and the cutting and modification are completed.

[0088] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for relocating old and new sewage wells without interrupting water supply, characterized in that: Includes the following steps: Step 1: Investigate the existing well cutting conditions, including whether there is a flow channel, operating water level, flow rate, flow velocity, and surrounding environment; Step 2: Based on whether there is a flow channel in the existing well, the construction method for cutting and modifying the existing well is divided into two categories: construction method for cutting and modifying the existing well with a flow channel and construction method for cutting and modifying the existing well without a flow channel. Step 3: When there is no flow channel in the existing well, steel cofferdams are used for design, fabrication, assembly, and installation; when there is a flow channel in the existing well, steel flow channels are used for design, fabrication, assembly, and installation. Step 4: Cut the existing well top plate during construction, and then restore it to its original state. The cutting and modification are now complete.

2. The method for relocating old and new sewage wells without interrupting water supply according to claim 1, characterized in that: The method for modifying existing wells without flow channels includes the following steps: Step 1: Before construction, prepare the steel cofferdam, guide rails and guide beams, internal supports, water-stopping devices, auxiliary installation devices and connectors; Step 2: Make a hole in the top plate of the existing well, and then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam. Use a wire saw to cut it, and lift it out in sections according to the size of the lifting equipment. Step 3: Steel cofferdam installation. After marking the positioning lines on the wall, a suspended basket is first lowered into the well. Expansion bolts are used to secure the guide rails from top to bottom. Then, a hand-operated hoist is installed. The steel cofferdam is then hoisted down into the well as a whole using a truck crane. During the lowering process, the hand-operated hoist is tightened while lowering to ensure the steel cofferdam is flush against the well wall. After the steel cofferdam is in place, workers secure the inner fixing bolts of the part above the water surface and pump water to check for leaks. Depending on the leakage situation, other water-stopping measures are implemented. Step 4: Demolish the existing well wall, use a steel ladder to lower the new well, use a mobile frame to drill holes in the well wall and thread ropes and install guide wheels, then cut the concrete at the opening into multiple pieces according to the lifting equipment, pull them out by hand chain hoist and hoist them out by guide wheels, and then perform anti-corrosion treatment on the cut surfaces. Step 5: Steel cofferdam dismantling. After anti-corrosion treatment, first remove the fixing bolts on both sides from bottom to top, loosen the hand chain hoist, lift out the steel cofferdam, and use a suspended basket to dismantle the steel guide rails.

3. The method for relocating old and new sewage wells without interrupting water supply, as described in claim 2, is characterized in that: The steel cofferdam is designed in an arc shape to accommodate the high-speed water flow in the existing well; the steel cofferdam is equipped with reinforcing plates and steel supports inside.

4. The construction method for relocating old and new sewage wells without interrupting water supply according to claim 2, characterized in that: The water-stopping device consists of three water-stopping measures: a P-type rubber water-stopping strip on the outer side and bottom, a steel plate and flat rubber on the inner side, and a cotton-filled space in the middle; the auxiliary installation device is a hand-operated hoist installed between the steel cofferdam and the well wall.

5. The construction method for relocating old and new sewage wells without interrupting water supply according to claim 1, characterized in that: The method for modifying existing wells with flow channels includes the following steps: Step 1: Before construction, prepare the steel flow channel, limiting beam, internal support, water-stopping device, fasteners, and work safety measures; Step 2: Open a hole in the existing well top plate, then determine the cutting range of the existing well top plate according to the working environment and the size of the steel cofferdam, cut it with a wire saw, and lift it out in sections according to the size of the lifting equipment; Step 3: Before installation, install the downstream steel flow channel limiting beam. Fix it to the existing plain concrete flow channel of the well with expansion bolts. Then, use lifting equipment to hoist the entire steel flow channel into the well. First, pre-install the steel flow channel, then correct the steel flow channel, and finally complete the lowering. Step 4: The existing concrete channel of the well is demolished in one stage. A part of the existing channel is retained on the side of the steel channel. It is chiseled at an angle to ensure the stability of the working surface. Step 5: Demolish the existing well wall, use a steel ladder to lower the new well, use a mobile frame to drill holes in the well wall and install ropes and guide wheels, cut the concrete at the opening into multiple pieces according to the lifting equipment, pull them out by hand chain hoists, and then perform anti-corrosion treatment on the cut surfaces. Step Six: Two-stage demolition of the existing concrete flow channel. The remaining portion of the existing flow channel will be removed using two pneumatic picks, and the excavated soil will be hoisted out using a hopper. Step 7: Next, the steel flow channel is dismantled. Workers wearing safety belts and gas masks loosen the fixing bolts of the steel flow channel and release water from one side to balance the water level on both sides. Taking into account the weight of the water, a large-scale lifting and hoisting equipment is used to lift the steel flow channel out.

6. The construction method for relocating old and new sewage wells without interrupting water supply according to claim 1, characterized in that: The steel flow channel is designed according to the shape of the existing plain concrete flow channel; the limiting beam is made of steel and is fixed to the existing plain concrete flow channel with expansion bolts.

7. The method for relocating old and new sewage wells without interrupting water supply according to claim 1, characterized in that: The steel flow channel is equipped with steel supports inside; a fixed steel plate is installed on the steel flow channel and fixed with expansion bolts.

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