Method and apparatus for installing an extended well and appurtenances in soft ground

Abstract

The application relates to the technical field of soft soil foundation treatment and underground equipment installation, in particular to an extension well for a soft soil foundation and a method and device for installing the extension well and accessories. The method comprises the following steps: first-layer extension well assembly: hoisting the first-layer extension well, adjusting the hoisting posture and position of the extension well, aligning the lower end port of the first-layer extension well with the receiving port of the connecting short pipe on the top of the tank, coaxially aligning the first-layer extension well with the connecting short pipe, forming a stable stress structure relying on preset anchor points, applying vertical uniform tension to the first-layer extension well in the form of uniform axial pulling, guiding the first-layer extension well to stably fall, and coaxially sealingly inserting the first-layer extension well into the connecting short pipe on the top of the tank; multi-layer extension well butt joint assembly, installing a plastic top assembly, and carrying out layered backfilling, compaction and grouting construction; and the application can improve the precision and reliability of the extension well socket installation.

Description

Technical Field

[0001] This application relates to the field of soft soil foundation treatment and underground equipment installation technology, and in particular to a method and apparatus for installing extension wells and accessories for soft soil foundations. Background Technology

[0002] Soft soil foundations possess the unique structure of soft clay layers, exhibiting characteristics such as large thickness, unevenness, high water content, large void ratio, low strength, high compressibility, strong rheological properties, and slow drainage consolidation, resulting in poor foundation stability. When burying underground equipment such as oil-water separators, grease traps, and storage tanks in soft soil foundations, it is usually necessary to install one or more extension wells above their inspection ports to connect the surface with the underground equipment, meeting the needs of daily maintenance, cleaning, ventilation, and personnel access.

[0003] The short pipe connecting the FRP extension well and the tank body generally adopts a socket-type sealing connection structure. Water-stop sealing is achieved by installing a rubber sealing ring inside the socket. Due to the high surface friction coefficient of FRP material and the high compression ratio of the rubber sealing ring to meet the requirements of underground seepage prevention and water seepage prevention, it is necessary to overcome great axial assembly resistance when the extension well and the socket of the connecting short pipe are connected. At present, two traditional methods are generally used on the construction site: one is to use the excavator bucket to push the upper end face of the extension well, and the other is to have multiple workers use sledgehammers to strike it symmetrically.

[0004] Regarding the two methods mentioned above, when the excavator pushes, the small contact area between the bucket and the extension well can easily cause chipping or cracking of the upper end of the fiberglass. At the same time, it is difficult to precisely control the direction of the excavator's thrust, which often leads to the extension well being inserted at an angle. This results in over-compression on one side of the sealing ring and under-compression on the other side, or even squeezing the sealing ring out of the groove and causing it to fail completely. The sledgehammer striking method relies on impact loads, and the peak impact force far exceeds the static allowable stress of fiberglass, which can easily produce radial cracks on the end face of the socket. In addition, it is difficult for multiple people to strike in sync, which can also generate eccentric torque and cause the axis to deviate. Summary of the Invention

[0005] To improve the accuracy and reliability of the socket installation of extension wells, this application provides a method and apparatus for installing extension wells and accessories on soft soil foundations, adopting the following technical solution: In a first aspect, the present invention provides a method for installing an extension well and its accessories on a soft soil foundation, comprising the following steps: Extension well alignment: Align and coaxially align the lower end of the extension well with the bearing interface of the receiving structure; Pulling: At least three sets of preset anchor points are symmetrically set between the extension well and the receiving structure, and a uniform axial tension is applied synchronously through each set of preset anchor points to pull the extension well vertically down until its lower end port is sealed and inserted into the receiving interface. Plastic top assembly installation: Install the plastic top assembly at the upper port of the uppermost extension well, so that the plastic top assembly is connected to the extension well in a socket seal. Layered backfilling: Crushed stone is backfilled in layers around the receiving structure and extension well to form multiple layers of crushed stone, and horizontal pressure is injected into the receiving structure at the same time; after each layer of crushed stone is compacted to the preset density, cement grout is poured.

[0006] By adopting the above technical solution, multiple sets of symmetrical anchor points are used to simultaneously apply axial tension to pull the extension well. The force is uniform and there is no eccentric impact, which can ensure that the extension well remains coaxial and vertically sinking throughout the process. The rubber sealing ring is uniformly compressed, and there will be no problems such as local overpressure or failure due to detachment. This effectively protects the FRP well body from edge chipping and cracking. During the backfilling process, water is injected into the receiving tank at the same time. The internal hydrostatic pressure is used to offset the lateral soil pressure of the crushed stone on the outside, preventing the receiving structure from being deformed by pressure. The layered crushed stone and cement grout are poured to form an integral cushion layer, which is suitable for soft soil foundations and greatly reduces the risk of uneven settlement and equipment floating in the later stage.

[0007] Optionally, in the layered backfilling step, the crushed stone particle size is 0-16 mm and the compaction degree is 35-45 MPa.

[0008] By adopting the above technical solution, 0mm-16mm continuously graded crushed stone is easier to compact (and can achieve higher density), has a larger internal friction angle, and the resulting backfill has higher bearing strength and shear resistance, and its cost is lower than that of 2-5mm selected crushed stone.

[0009] Optionally, in the layered backfilling step, after backfilling three layers of crushed stone and pouring cement slurry around the first extension well, a concrete anchor plate is poured around the extension well.

[0010] By adopting the above technical solution, after the three layers of crushed stone are compacted and grouted, a bearing base with uniform rigidity and precise elevation is formed. On this basis, a concrete anchor plate is poured to rigidly constrain the first-layer extension well, offset the uneven lateral pressure of the soft soil, avoid the overturning of the well cylinder and the tearing and leakage at the interface between the tank and the extension well, and at the same time increase the contact area between the extension well and the surrounding soil to resist the high groundwater buoyancy of the soft soil foundation.

[0011] Optionally, the extension well is located in the middle of the concrete anchor plate, which is 470mm away from the wall of the extension well and has a pouring thickness of 150mm or three-quarters of the thickness of the crushed stone layer.

[0012] By adopting the above technical solution, the anchor plate has a reserved buffer support width of 470mm and a limited fixing thickness, ensuring that the concrete fully wraps and limits the well flange, resulting in symmetrical and balanced force distribution and reducing the skewing caused by insufficient unilateral restraint. The standard thickness of 150mm is moderate, providing sufficient bending and shear stiffness to resist uneven lateral thrust of soft soil without excessively increasing the amount of concrete used. The three-quarters thickness of the crushed stone layer can be flexibly adjusted according to the actual thickness of the first layer of crushed stone cushion on site, ensuring that the thickness of the anchor plate matches the stiffness of the lower crushed stone cushion layer and avoiding stress concentration caused by abrupt changes in stiffness between the upper and lower layers.

[0013] Optionally, in the layered backfilling step, after the backfilled crushed stone passes over the concrete anchor plate, the compaction degree of the crushed stone layer gradually increases, and the maximum compaction degree of the surface crushed stone layer near the top plastic component is 45-60 MPa; two layers of crushed stone with a compaction degree of 40-60 MPa are laid below it, forming a three-layer progressive compaction structure.

[0014] By adopting the above technical solution, after the extension well is spliced ​​upward, its cantilever effect becomes more and more significant as the extension well increases in height, and the risk of overturning increases with height. The compaction degree increases layer by layer. Its mechanical purpose is to provide a stronger lateral constraint spring around the main column in each backfill layer, resisting and limiting its lateral displacement layer by layer, and improving the overall verticality and long-term stability of the wellbore.

[0015] Optionally, in the layered backfilling step, the compaction degrees of the two layers of crushed stone at the top of the plastic component are 35-45MPa and 45-60MPa respectively, forming a compaction step.

[0016] By adopting the above technical solution, using two steps of 35-45MPa and 45-60MPa, a standard roadbed construction method is employed. The lower layer serves as a transition layer, while the upper layer is a high-strength bearing layer, providing a uniform, dense, and high-strength elastic foundation for the concrete bearing slab, preventing the bearing slab from cracking during use.

[0017] Optionally, an accessory installation step may be set between the plastic top component installation step and the layered backfilling step; Attachment installation: Install the attachments at the preset elevation position inside the extension well.

[0018] By adopting the above technical solution, the internal accessories such as sensors and coalescing units are assembled before backfilling and top sealing, avoiding the risks of vibration and debris falling during traction and backfilling construction, accurately controlling the installation elevation of accessories, and ensuring the stable and reliable monitoring and alarm functions of oil layer, sludge, and overflow.

[0019] Secondly, the present invention provides an installation device for an extension well and its accessories for soft soil foundations, used to implement a method for installing extension wells and their accessories, and adopts the following technical solution: An extension well installation device for soft soil foundation includes a traction mechanism, which includes multiple tension screw assemblies, a first connecting part and a second connecting part; the tension screw assembly includes a tension screw and a traction nut, and the traction nut is threadedly engaged with the tension screw; The first connecting part is located at one end of the tension screw and is used to connect with the fixed anchor point; the second connecting part is located on the tension screw and between the traction nut and the first connecting part, and is used to connect with the extension well to be installed; when the traction nut is rotated, the traction nut moves along the axial direction of the tension screw and pushes the second connecting part toward the first connecting part, pulling the extension well axially into the bearing interface; The first connecting part and the second connecting part can be adapted to switch between two installation conditions, respectively realizing the assembly of the extension well and the tank short pipe, and the splicing assembly between adjacent extension wells.

[0020] By adopting the above technical solution, a static traction mode of axial push-pull using a screw and nut is employed, which differs from impact and unilateral compression force application. Relying on multiple sets of tension screws to apply force synchronously ensures uniform circumferential force on the extension well. Simultaneously, the first and second connecting parts can be quickly switched in assembly form without replacing the entire traction tooling set, adapting to both first-level well-tank docking and upper / lower well splicing conditions. The tooling is highly versatile, reducing on-site tooling adjustment time. The screw thread drive force application method allows for precise control of traction displacement and traction rate, further ensuring the coaxiality of the extension well's socket and preventing seal ring extrusion failure.

[0021] Optionally, when adapting to the tank assembly condition, the first connecting part includes a lower support frame and several lower fixed feet. The lower fixed feet are fixed to the lower end of the tension screw and abut against the side of the tank connecting short pipe. The second connecting part is an upper support frame. The upper support frame slides through the tension screw and is mounted on the outside of the upper port of the extension well. The traction nut is located above the upper support frame. Rotating the traction nut presses down the upper support frame to complete the traction.

[0022] By adopting the above technical solution, the lower fixed foot is snapped into the edge of the connecting short pipe, the anchoring point is stable and not easy to slip, and the rigid structure of the tank provides reaction force to avoid the anchoring point from shifting during the traction process; the upper and lower support frames have a separate sliding structure, which is adapted to the top-down traction assembly logic of the first well, and the force application path is direct and stable.

[0023] Optionally, when adapting to the well body splicing condition, the first connecting part is a lower positioning pull ring, which is fixed to the lower end of the tension screw and hooked onto the lower extension well outer wall ear plate; the second connecting part is an upper positioning pull ring, which is slidably inserted through the tension screw and hooked onto the upper extension well outer wall ear plate. The traction nut moves down to push the upper positioning pull ring closer to the lower positioning pull ring to achieve the docking and pulling of the two well bodies; Both the upper positioning pull ring and the lower positioning pull ring include a pull ring body and a hook disposed on the pull ring body. The hook is used to engage with the connecting lug on the outer wall of the extension well.

[0024] By adopting the above technical solution, the original ear plate on the outer wall of the extension well is selected as the traction point, avoiding the thin-walled and weak pressure-bearing areas of the well wall, thus preventing well wall depression and cracking; the bidirectional pull ring pull ensures that the upper and lower well bodies are subjected to equal circumferential force, eliminating splicing misalignment and sealing ring bias; the pull ring and the extension well ear plate can be quickly attached and detached without bolt fastening, improving the construction efficiency during multi-layer installation.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. Multiple sets of symmetrical anchor points are used for synchronous axial pulling, replacing traditional hammering and excavator extrusion impact construction. The extension well sinks vertically and coaxially throughout the entire process, and the sealing ring is evenly compressed and does not come out, eliminating the problems of fiberglass wellhead cracking, socket misalignment and leakage.

[0026] 2. A three-layer crushed stone cushion layer and a concrete anchor plate limiting structure are set up for the first-level extension well. The anchor plate is standardized in size and relies on the lower layer of grouting crushed stone to form a stable bearing base. The well flange is rigidly locked to resist the uneven lateral pressure of soft soil and effectively prevent the first-level well from overturning and the tank body and the extension well interface from tearing and leaking.

[0027] 3. Gradient progressive compaction backfilling is adopted, and the compaction degree of crushed stone in the raised section of the well shaft increases step by step to form multi-layer lateral constraints, which offsets the overturning effect of the well shaft cantilever; two-stage compaction steps are set at the top to provide a uniform elastic subgrade for the heavy-duty concrete bearing plate on the ground, avoid cracking of the surface bearing plate, and adapt to the long-term settlement and deformation conditions of soft soil foundation.

[0028] 4. During the entire backfilling process, horizontal pressure is injected into the tank to counteract the lateral soil pressure of the crushed stone and prevent the fiberglass tank from being squeezed and deformed; 0-16mm graded crushed stone is layered and cement slurry is poured to form an integral shell, which improves the overall anti-buoyancy performance of the equipment and greatly reduces the risk of equipment damage caused by uneven settlement of soft soil and groundwater buoyancy. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the traction mechanism in the extension well installation device under the docking condition of the first well tank of the extension well in the embodiment of this application; Figure 2 This is a schematic diagram of the partial three-dimensional structure of the traction mechanism after the extension well is removed in the docking condition of the first well tank of the extension well installation device in the embodiment of this application. Figure 3 This is a three-dimensional structural diagram of the extension well installation device in the embodiments of this application; Figure 4This is a schematic diagram of the overall three-dimensional structure of the traction mechanism in the extension well splicing operation of the extension well installation device in the embodiments of this application. Figure 5 This is an embodiment of the present application. Figure 4 A magnified view of a portion of region A in the middle.

[0030] Reference numerals: 100, tension screw assembly; 110, tension screw; 111, connecting lock nut; 112, fixing nut; 113, baffle; 120, traction nut; 200, first connecting part; 210, lower support frame; 220, lower fixed foot; 230, lower positioning pull ring; 300, second connecting part; 310, upper support frame; 320, upper positioning pull ring; 321, pull ring body; 322, hook; 400, extension well to be installed; 410, connecting ear plate; 500, connecting short pipe; 510, side guard. Detailed Implementation

[0031] The following combination Figures 1 to 5 This application will be described in further detail.

[0032] In coastal and lacustrine soft soil areas, the construction of fiberglass extension wells for underground oil-water separators commonly presents several challenges: long-term rheological changes in soft soil and high buoyancy of groundwater result in high compressive resistance of the sealing rings between the extension well and the tank's short pipe. Traditional impact-based assembly methods are prone to causing brittle cracking of the fiberglass and detachment of the sealing rings. Furthermore, lateral soil pressure during backfilling can cause axial movement and radial tilting of the well, leading to displacement failure of monitoring sensors later on. To address these challenges, this application utilizes a dual-condition switching screw-driven static traction structure, combined with differentiated backfilling and reinforcement techniques for soft soil, to achieve non-destructive, high-precision assembly of the extension well, adaptable to long-term soft soil settlement conditions.

[0033] This application discloses an installation device for installing an extension well; This embodiment is a special installation device for installing an extension well, including a traction mechanism. The traction mechanism includes multiple tension screw assemblies 100, a first connecting part 200 and a second connecting part 300. The tension screw assembly 100 includes a tension screw 110 and a traction nut 120, and the traction nut 120 is threadedly engaged with the tension screw 110. The first connecting part 200 is provided at one end of the tension screw 110 and is used to connect with the fixed anchor point; the second connecting part 300 is provided on the tension screw 110 and located between the traction nut 120 and the first connecting part 200, and is used to connect with the extension well to be installed; when the traction nut 120 is rotated, the traction nut 120 moves axially along the tension screw 110 and pushes the second connecting part 300 toward the first connecting part 200, thereby pulling the extension well axially into the bearing interface; Each tension screw assembly 100 includes one tension screw 110 and one traction nut 120. Preferably, there are three tension screws 110, evenly distributed around the circumference of the extension well to be installed. Each tension screw 110 is composed of multiple screw segments connected end-to-end by a connecting nut. In this embodiment, two screw segments are preferred, with threads at the connection points. The connecting nut threads-connects the two screw segments. Rotating the connecting nut allows adjustment of the total length of the tension screw 110 to accommodate extension well installations of different heights.

[0034] The first connecting part 200 and the second connecting part 300 can be adapted to switch between two installation conditions, respectively realizing the assembly of the extension well and the tank short pipe, and the splicing assembly between adjacent extension wells. The traction mechanism has two forms.

[0035] The first specific form is the docking condition of the first-level well tank: it is suitable for the docking installation condition of the first-level extension well and the short pipe 500 connecting the inspection port of the fiberglass tank. Since the outer wall of the connecting short pipe at the top of the fiberglass tank is not provided with a connecting lug, the bottom anchoring reaction force is relied on the inner side of the short pipe 510. The first connecting part 200 includes a lower support frame 210 and a lower fixed foot 220. The lower support frame 210 is movably mounted on each tension rod 110. The lower support frame 210 has a three-arm radial symmetrical structure. The angle between the three support rods is maintained at 120°. It is located above the lower fixed foot 220 to maintain the axial stability of each tension rod 110 and prevent the rod from swaying laterally when it is under pressure.

[0036] The lower fixed foot 220 is used to connect with the baffle 113 of the connecting short pipe 500 of the tank inspection port. The lower fixed foot 220 includes a foot body and an anti-slip layer fixedly installed on the foot body. The baffle 113 is formed on the lower section of the screw rod. The foot body is sleeved on the lower section of the screw rod and fixed by screwing in the fixing nut 112, so that the foot body is pressed tightly on the baffle 113. The foot body is used to abut against the edge 510 of the connecting short pipe 500 of the FRP tank inspection port. A 3mm thick anti-slip rubber pad is pasted on the inner side of the lower fixed foot 220. In use, it is snapped and anchored to the lower side of the annular edge 510 at the top of the oil-water tank connecting short pipe 500. It relies on the rigid shell of the tank to provide tensile reaction force to prevent the anchor point from slipping or shifting.

[0037] The second connecting part 300 is an upper sliding support frame, which slides through the outside of the three tension screws 110. The upper sliding support frame is also a three-arm radially symmetrical structure. The included angle of the three support rods is 120°. The radial dimension of the three support rods of the support frame is larger than the outer diameter of the extension well to be installed. An 8mm thick polyurethane ballast pad is bonded to the end. The pad directly fits the end face of the upper port of the extension well to disperse local stress and avoid rigid compression and impact on the brittle fiberglass well wall.

[0038] The working principle of the first configuration in this embodiment is as follows: The lower fixed foot 220 is anchored to the baffle 113 on the short pipe of the tank body, and the upper support frame 310 is adjusted so that the ballast pad is in contact with the edge of the upper port of the extension well. Three tension screw assemblies 100 are evenly arranged around the circumference of the extension well. Under unified command, the construction personnel rotate each traction nut 120 synchronously and symmetrically. When the traction nuts 120 rotate, they move downward, jointly pushing the upper support frame 310 downward to press the upper port of the extension well, thereby gradually pressing the extension well into the socket. When the installation mark line on the outer wall of the extension well is flush with the end face of the socket, the traction is stopped and the traction device is removed.

[0039] The second specific configuration is for inter-layer extension well splicing: it is adapted for connecting two extension wells 400 to each other, used to install the upper extension well onto the fixed lower extension well. The lower extension well has prefabricated connecting ear plates on its outer wall, which can be quickly hooked to form anchor points. In this configuration, the composition of the tension screw assembly 100 is the same as in the first configuration. The first connecting part 200 is a lower positioning pull ring 230, which is fixedly installed at the lower end of the tension screw 110 and hooks the prefabricated ear plates on the outer wall of the lower extension well that has already been installed. The second connecting part 300 is an upper positioning pull ring 320, which slides through the tension screw 110 and hooks the prefabricated ear plates on the outer wall of the upper extension well to be spliced. The two sets of positioning pull rings are integrally formed with bent hooks 322, which are hooked and cooperate with the ear plates.

[0040] The working principle under the second working condition is as follows: the lower positioning pull ring 230 is fixed to the lower end of each lead screw and hooked onto the connecting ear plate 410 of the lower extension well; the upper positioning pull ring 320 is inserted into the upper end of each lead screw and hooked onto the connecting ear plate 410 of the upper extension well; finally, the traction nut 120 is screwed onto each lead screw above the upper positioning pull ring 320. The three tension lead screw assemblies 100 are evenly arranged around the circumference of the extension well. The construction personnel simultaneously rotate each traction nut 120, and the nuts move downward, pushing the upper positioning pull ring 320 downward, so that the upper positioning pull ring 320 and the lower positioning pull ring 230 move closer to each other, thereby smoothly pulling the upper extension well into the lower socket.

[0041] This application also provides a method for installing extension wells and accessories for soft soil foundations. This method relies on the aforementioned extension well installation device and distinguishes three typical construction scenarios based on the number of installation layers and whether concrete anchor plates are installed, corresponding to three sets of method implementation examples. The specific construction process is as follows: Example 1: Single-layer extension well directly assembled with plastic top components (no multi-layer splicing, no concrete anchor plate) This embodiment is suitable for small oil-water separation equipment with shallow foundation pit depth, low groundwater level, and low risk of soft soil uplift and overturning. It only has a single extension well and does not require the pouring of concrete anchor plates. The construction steps are as follows: Extension well alignment: Align and coaxially align the lower end of the extension well with the receiving interface of the receiving structure.

[0042] Specifically, when hoisting the single-layer fiberglass extension well, apply special rubber grease to the sealing ring at the lower end of the well body, and manually adjust the hoisting posture to ensure that the lower end of the extension well is completely coaxially aligned with the receiving interface of the 500mm connecting pipe to the tank body.

[0043] Pulling: At least three sets of preset anchor points are symmetrically set between the extension well and the receiving structure, and a uniform axial tension is applied synchronously through each set of preset anchor points to pull the extension well vertically down until its lower end port is sealed and inserted into the receiving interface.

[0044] Specifically, the traction mechanism is switched to the tank docking mode, and three sets of tension screw assemblies 100 are evenly arranged along the circumference of the well at 120°. The lower fixed foot 220 clamps the short pipe annular retaining edge 510, and the upper support frame 310 is erected on the upper port of the extension well. The three sets of traction nuts 120 are rotated at the same speed, and the well body is pulled vertically down by the uniform axial tension until the well body scale line is aligned with the short pipe and the sealing ring is completely sealed. Then the traction tooling is removed, and multiple sets of symmetrical anchor points are used to apply axial tension to pull the extension well. The force is uniform and there is no eccentric impact, which can ensure that the extension well remains coaxial and vertically descending throughout the process. The rubber sealing ring is evenly compressed and there will be no problems of local overpressure or failure. This effectively protects the fiberglass well body from chipping and cracking.

[0045] Plastic top assembly installation: Install the plastic top assembly at the upper port of the uppermost extension well, so that the plastic top assembly is connected to the extension well in a socket seal.

[0046] Specifically, the installation of the plastic top assembly: After applying grease to the contact surface of the plastic top assembly, it is directly inserted and assembled to the single-layer extension wellhead port to achieve wellhead sealing; Attachment Installation: Install the attachments at the preset elevation position inside the extension well. Specifically, oil layer, sludge, and overflow alarm sensors are installed at preset elevations inside the extension well. Cables are fixed along the well wall. The internal sensors and coalescing units are assembled before backfilling and top sealing to avoid displacement and damage of components caused by backfilling vibration and falling gravel. The installation elevation is precisely controlled to ensure the long-term stability of oil-water monitoring and sludge alarm functions.

[0047] Layered backfilling: Crushed stone is backfilled in layers around the receiving structure and extension well to form multiple layers of crushed stone, and horizontal pressure is injected into the receiving structure at the same time; after each layer of crushed stone is compacted to the preset density, cement grout is poured.

[0048] Specifically, 0-16mm graded crushed stone is backfilled in layers around the tank and extension well, with a single layer thickness of 200mm. The compaction degree of the first three layers of crushed stone is controlled at 35-45MPa. Cement grout is poured after each layer is compacted. 0mm-16mm continuous graded crushed stone is easier to compact (achieving higher density), has a larger internal friction angle, and the resulting backfill has higher load-bearing strength and shear resistance. Moreover, its cost is lower than that of 2-5mm selected crushed stone. After the three layers of crushed stone are grouted and cured, no concrete anchor plate is poured, and backfilling continues in layers upwards. After the height of the crushed stone exceeds the main body of the tank, a progressive compaction process is adopted. The compaction degree of the lower layer of crushed stone is 40-60MPa, and the surface layer of crushed stone near the top plastic component is 45-60MPa. Two compaction steps are set below the top plastic component: 35-45MPa for the lower layer and 45-60MPa for the upper layer.

[0049] Example 2: Multi-layer extension well assembly with plastic top component (multi-layer splicing, no concrete anchor plate) This embodiment is suitable for situations where the burial depth is large, multiple sections of well body are needed to raise the wellhead, but the lateral thrust of soft soil and the buoyancy of groundwater are relatively small. A multi-layer well body splicing scheme is adopted, and no concrete anchor plates are poured throughout the process. The steps are as follows: The process of positioning the foundation pit and tank body and pulling and assembling the first single-layer extension well is the same as in embodiment 1. After the first layer well and tank body are sealed and connected, the traction tooling accessories corresponding to the tank body connection condition are removed.

[0050] Multi-layer extension well segment splicing: Switch the traction mechanism to inter-layer splicing mode, remove the lower support frame 210 and lower fixed foot 220, and replace and assemble the lower positioning pull ring 230 and upper positioning pull ring 320; the lower positioning pull ring 230 is attached to the outer wall ear plate of the first-layer extension well, and the upper positioning pull ring 320 is attached to the outer wall ear plate of the upper-layer well to be spliced; the three sets of screws synchronously and uniformly rotate the traction nut 120 to pull the two well sections to achieve coaxial sealing and insertion; repeat this operation to complete the splicing of multiple extension well sections in sequence to form an integral multi-layer well body. Accessory installation: After all well bodies are spliced, coalescing units and three sets of monitoring and alarm sensors are installed at preset elevations in each layer inside the well. Plastic top component installation: Install a reducing diameter connecting pipe at the upper end of the uppermost extension well, and then seal the plastic top component with a socket on the upper end of the reducing diameter pipe.

[0051] Layered backfilling construction: 0-16mm graded crushed stone is backfilled in layers around the tank and extension well, with a single layer thickness of 200mm. The first three layers of crushed stone are compacted to a pressure of 35-45MPa, and cement grout is poured after each layer is compacted. 0mm-16mm continuously graded crushed stone is easier to compact (achieving higher density), has a larger internal friction angle, and the resulting backfill has higher load-bearing strength and shear resistance. Its cost is also lower than that of 2-5mm selected crushed stone. Three layers of 0-16mm crushed stone are backfilled around the tank, with a compaction pressure of 35-45MPa, and cement grout is poured after each layer is compacted. No concrete anchor plates are poured throughout the process. After the crushed stone backfill height exceeds the tank height, a three-layer progressive compaction structure is adopted: the bottom two layers are compacted to 40-60MPa, and the surface wellhead area is compacted to 45-60MPa. A 35-45MPa and 45-60MPa compaction pressure is set below the plastic top component. Two-stage compaction steps, layered cement grouting, and overall cemented crushed stone wrapping the well body to resist lateral movement and floating.

[0052] The risk of overturning of the cantilever is significantly increased after the extension well is heightened. The compaction degree of the backfill crushed stone increases layer by layer, and the lateral constraint of the well barrel is strengthened layer by layer to limit the radial displacement of the well body. The verticality of the well barrel is stable during long-term use and it is suitable for the rheological deformation environment of soft soil.

[0053] Example 3: Casting concrete anchor plates (standard heavy-load soft soil foundation conditions) This embodiment is applicable to scenarios with deep soft soil along the coast, high groundwater levels, and equipment subjected to long-term ground vehicle loads, requiring high resistance to overturning and buoyancy. It employs a multi-layer well splicing process and adds concrete anchor plates for reinforcement, fully covering all the technical features of the method claims in this application. The steps are as follows: the foundation pit pretreatment, tank fixing, static tensioning and assembly of the first-layer extension well with threaded rods, and the multi-layer extension well segment-by-segment splicing steps are the same as in Embodiment 2, with the addition of a concrete anchor plate pouring step. After the three layers of crushed stone grouting have cured to the required standard, C35 / 45 concrete anchor plates are poured with the extension well as the center. The outer wall of the well is 470mm away from the inner side of the anchor plate. The pouring thickness is 150mm. A single layer of Φ10@100 steel mesh is laid inside the plate and cured to the design strength. Specifically, a three-layer grouting crushed stone system forms a uniform and stable bearing base. On this base, a standardized concrete anchor plate is poured to rigidly wrap and constrain the first-layer well shaft, offsetting the uneven lateral thrust of the soft soil and preventing well shaft overturning, tearing, and leakage at the interface between the tank and the extension well. The 470mm buffer width and 150mm standard thickness provide symmetrical and balanced stress, with sufficient bending and shear stiffness. At the same time, the plate thickness can be adaptively adjusted according to the thickness of the crushed stone cushion layer (3 / 4 of the cushion layer thickness) to avoid stress concentration caused by abrupt changes in stiffness between the upper and lower layers. This increases the contact area between the well shaft and the soil, improving the equipment's anti-buoyancy capability.

[0054] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for installing an extension well and its accessories for soft soil foundations, characterized in that: Includes the following steps: Extension well alignment: Align and coaxially align the lower end of the extension well with the bearing interface of the receiving structure; Pulling: At least three sets of preset anchor points are symmetrically set between the extension well and the receiving structure, and a uniform axial tension is applied synchronously through each set of preset anchor points to pull the extension well vertically down until its lower end port is sealed and inserted into the receiving interface. Plastic top assembly installation: Install the plastic top assembly at the upper port of the uppermost extension well, so that the plastic top assembly is connected to the extension well in a socket seal. Layered backfilling: Crushed stone is backfilled in layers around the receiving structure and extension well to form multiple layers of crushed stone, and horizontal pressure is injected into the receiving structure at the same time; after each layer of crushed stone is compacted to the preset density, cement grout is poured.

2. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: In the layered backfilling step, the crushed stone particle size is 0-16 mm and the compaction degree is 35-45 MPa.

3. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: In the layered backfilling step, after backfilling three layers of crushed stone and pouring cement slurry around the first extension well, a concrete anchor plate is poured around the extension well.

4. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: The extension well is located in the middle of the concrete anchor plate, which is 470mm away from the wall of the extension well and has a pouring thickness of 150mm or three-quarters of the thickness of the crushed stone layer.

5. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: In the layered backfilling step, after the backfilled crushed stone passes over the concrete anchor plate, the compaction degree of the crushed stone layer gradually increases, and the maximum compaction degree of the surface crushed stone layer near the top plastic component is 45-60 MPa; two layers of crushed stone with a compaction degree of 40-60 MPa are laid below it, forming a three-layer progressive compaction structure.

6. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: In the layered backfilling step, the compaction degrees of the two layers of crushed stone at the top of the plastic component are 35-45MPa and 45-60MPa respectively, forming a compaction step.

7. The method for installing an extension well and its accessories for soft soil foundations according to claim 1, characterized in that: An accessory installation step is set between the plastic top component installation step and the layered backfilling step. Attachment installation: Install the attachments at the preset elevation position inside the extension well.

8. An extension well installation device for soft soil foundation, used to implement the extension well and accessory installation method according to claims 1-3, characterized in that: The traction mechanism includes a plurality of tension screw assemblies (100), a first connecting part (200) and a second connecting part (300); the tension screw assembly (100) includes a tension screw (110) and a traction nut (120), the traction nut (120) being threadedly engaged with the tension screw (110); The first connecting part (200) is located at one end of the tension screw (110) and is used to connect with the fixed anchor point; the second connecting part (300) is located on the tension screw (110) and between the traction nut (120) and the first connecting part (200) and is used to connect with the extension well to be installed; when the traction nut (120) is rotated, the traction nut (120) moves axially along the tension screw (110) and pushes the second connecting part (300) toward the first connecting part (200) to pull the extension well axially into the bearing interface; The first connecting part (200) and the second connecting part (300) can be adapted to switch between two installation conditions, respectively realizing the assembly of the extension well and the tank short pipe, and the splicing assembly between adjacent extension wells.

9. The extension well installation device for soft soil foundation according to claim 8, characterized in that: When adapting to the tank assembly condition, the first connecting part (200) includes a lower support frame (210) and several lower fixed feet (220). The lower fixed feet (220) are fixed to the lower end of the tension screw (110) and abut against the side (510) of the tank connecting short pipe (500). The second connecting part (300) is an upper support frame (310). The upper support frame (310) slides through the tension screw (110) and is mounted on the outside of the upper port of the extension well. The traction nut (120) is located above the upper support frame (310). Rotating the traction nut (120) presses down the upper support frame (310) to complete the traction.

10. The extension well installation device for soft soil foundation according to claim 8, characterized in that: When adapting to the well body splicing condition, the first connecting part (200) is a lower positioning pull ring (230), which is fixed to the lower end of the tension screw (110) and hooked onto the lower extension well outer wall ear plate; the second connecting part (300) is an upper positioning pull ring (320), which slides through the tension screw (110) and hooks onto the upper extension well outer wall ear plate. The traction nut (120) moves down to push the upper positioning pull ring (320) closer to the lower positioning pull ring (230) to realize the docking and pulling of the two well bodies; Both the upper positioning pull ring (320) and the lower positioning pull ring (230) include a pull ring body (321) and a hook (322) provided on the pull ring body (321). The hook (322) is used to engage with the connecting ear plate (410) on the outer wall of the extension well.

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