An installation method for a large-diameter steel pipe casing well

Abstract

The present invention relates to the field of environmental protection equipment, and a method for installing a large-diameter steel pipe socket well, which is used to implement a long-bottomed steel pipe well in relatively shallow water bodies such as lakes or rivers; the construction steps are as follows: Step 1, harden the riverbed within the cofferdam; Step 2, after the site hardening meets the standard, drill holes at the predetermined locations, calibrate the outer casing and install it into the holes, and the lower end of the outer casing reaches the preset underground depth; Step 3, use a full-casing pipe-rubbing drilling rig combined with a rotary drilling rig to construct the outer well pipe. First, hoist and align the outer well pipe and install it into the outer casing until the bottom of the outer well pipe reaches the bottom of the outer casing; then, use a rotary drilling rig to advance soil extraction inside the outer casing, and at the same time, press the outer well pipe into the cycle construction until the preset underground depth; Step 4, pour the bottom seal at the bottom of the outer diameter pipe; Step 5, fill the space between the outer casing and the outer well pipe with gravel, and pull out the outer casing while backfilling the gravel; Step 6, hoist the inner well pipe in sections and place it into the outer well pipe and install it in place.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection equipment, specifically to the technical field of construction methods of environmental protection equipment used for improving and purifying water bodies in natural waters such as lakes, and particularly to an installation method of a large-diameter steel pipe sleeve well. Background Art

[0002] With the increasingly serious global warming and environmental pollution, water bodies (such as lakes or rivers) have shown relatively serious eutrophication, resulting in the outbreak of cyanobacteria. The applicant filed a Chinese invention patent application with the application number 201710585437.X and the title "Cyanobacteria Deep Well Treatment Equipment and Cyanobacteria Treatment Method" on July 18, 2017. The cyanobacteria deep well treatment equipment includes: a deep well with a water inlet at the top and inserted into the bottom of the water body, a drainage device opened on the side of the deep well and higher than the bottom of the water body, one end of the drainage device is connected to a drain pipe, and the other end of the drain pipe extends towards the bottom of the deep well. Through the cyanobacteria deep well treatment equipment and the cyanobacteria treatment method shown in the present invention, the hydrostatic pressure formed by the water introduced into the deep well at the bottom of the deep well can be used to crush cyanobacteria to form cyanobacteria fragments, and the negative pressure formed by the drainage device can be used to drain cyanobacteria towards the bottom of the deep well and discharge them from the deep well, so that they can be directly preyed on by fish, zooplankton and benthic animals in the water body, realizing the efficient ecological treatment of cyanobacteria, effectively preventing the outbreak of cyanobacteria and effectively improving water quality, thus curbing the outbreak of cyanobacteria from the source, reducing the prevention and treatment cost of cyanobacteria, and avoiding the generation of odors.

[0003] Furthermore, the applicant of this case filed a Chinese invention patent application with the application number CN201810220424.7 and the title "An Underwater Installation Method of a Large-diameter Sealed-bottom Steel Pipe Well" on March 16, 2018. This application relates to an underwater installation method of a deep well for purifying cyanobacteria as described above, including: an installation platform is set on the water surface with a bottom extending to the bottom of the water body and configured with four movably arranged brackets; a first outer pipe section with a closed bottom and a plurality of second outer pipe sections with open ends at both ends are vertically hoisted onto the brackets of the installation platform and buried into a pre-formed and vertically arranged cavity at the bottom of the water body to successively form an outer pipe well; a plurality of inner pipe sections with open ends at both ends are vertically hoisted onto the brackets of the installation platform and sleeved inside the outer pipe well to form an inner pipe well. The above prior art ensures that the outer pipe well and the inner pipe well are vertically placed into the pre-formed cavity with the help of the four movably arranged brackets equipped on the installation platform, and reduces the installation difficulty.

[0004] In the prior art, during the underwater installation of a steel pipe with a large diameter and a long longitudinal length in water, an installation method disclosed in, for example, publication numbers CN107191138A and CN113187401A can be adopted. The above prior art is generally applicable to the occasion of offshore oil drilling. Usually, the method of pouring concrete by lifting a steel reinforcement cage is adopted. In the solution, a steel pipe well with a large diameter and a sealed bottom is used, and the sinking difficulty is great, making it difficult to implement, and it is impossible to continue installing the inner pipe well. In addition, due to different geological conditions and the existence of soft soil layers, the use of ordinary slurry-supported hole drilling construction is likely to cause hole collapse; when installing the inner and outer pipe wells, the verticality cannot be guaranteed, and it is not easy to install in place. Summary of the Invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide an installation method for a large-diameter steel pipe sleeve well, which is used to implement a sealed-bottom steel pipe well with a long length in relatively shallow water bodies such as lakes or rivers.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] An installation method for a large-diameter steel pipe sleeve well, characterized in that it includes the following construction steps:

[0008] Step 1, construct a cofferdam in the selected area of the lake or river, and harden the riverbed within the cofferdam range;

[0009] Step 2, after the site hardening meets the standard, use a full-casing pipe-rubbing drilling rig to drill holes at the predetermined location. The center of the pipe gripper of the full-casing drilling rig corresponds to the center of the hole position. After calibrating the outer casing, install it into the hole. The lower end of the outer casing reaches the preset underground depth, and the upper end of the outer casing extends out of the ground;

[0010] Step 3, use the full-casing pipe-rubbing drilling rig in combination with a rotary drilling rig to construct the outer well pipe. The bottom of the outer well pipe is hollow; first, hoist and align the outer well pipe and install it into the outer casing until the bottom of the outer well pipe reaches the bottom of the outer casing; then, use a rotary drilling rig to advance and excavate soil in the outer casing, and at the same time press in the outer well pipe, and cycle the construction to the preset underground depth;

[0011] Step 4, pour a seal at the bottom of the outer diameter pipe;

[0012] Step 5, set a backfill protection cap at the top of the outer well pipe, fill the space between the outer casing and the outer well pipe with crushed stones, and pull out the outer casing while backfilling the crushed stones;

[0013] Step 6, hoist and install the inner well pipe in sections into the outer well pipe, ensuring that the inner well pipe always remains in the center position of the outer well pipe and is installed in place.

[0014] The present invention adopts the above technical solution, which relates to an installation method for a large-diameter steel pipe sleeve well. The installation method adopts the above steps and has at least the following advantages:

[0015] 1. In step 2 of this solution, a full-casing pipe-rubbing drilling rig is used to drill a hole at a predetermined location and press in the outer casing, replacing the existing method of using a steel reinforcement cage to hoist and pour concrete. Directly pressing in the outer casing improves the construction efficiency compared to pouring concrete, creates the condition for installing the inner and outer well pipes underwater in a sleeve well, reduces the frictional resistance during the sinking of the outer well pipe, facilitates the smooth installation and sinking of the outer well pipe, and can ensure the verticality at the same time.

[0016] 2. Using the outer casing to replace the existing method of using a steel reinforcement cage to hoist and pour concrete can adapt to different geological conditions and avoid the risk of hole collapse. In step 5, after filling gravel between the outer casing and the outer well pipe, the outer casing can be pulled out of the hole and reused.

[0017] 3. The method of using an open steel well pipe for the outer well pipe, sinking and installing it in place and then sealing the bottom, can adopt a construction plan of advanced soil excavation and simultaneously pressing in the outer well pipe, reducing the difficulty of sinking a large-diameter bottom-sealed steel pipe well, improving the construction efficiency, and reducing the construction cost.

[0018] In a further solution, in step 2: the outer casing includes multiple connected and fixed casing segments. The rotary drilling rig first conducts advanced soil excavation at a predetermined location, and the pipe-rubbing drilling rig's jaws hold the casing segments and install them in sections. A certain length needs to be reserved on the bottom surface for each section of the casing segment to be pressed into the soil to connect the next section of the casing segment. During the installation process of the casing segments, the verticality of the outer casing is corrected at any time, and it is necessary to ensure that the verticality is controlled within 2‰ until the lower end of the outer casing reaches the preset underground depth. In this step, the outer casing is installed in a segmented manner, which has the advantages of reducing the construction difficulty and facilitating the control of verticality compared to an integral outer casing.

[0019] Preferably, in step 3, the outer well pipe includes multiple connected and fixed outer pipe segments. The outer well pipe is hoisted and centered in sections and installed into the outer casing. Before each section of the outer pipe segment is installed into the outer casing, the next section of the outer pipe segment needs to be connected and fixed. The jaws of the pipe-rubbing drilling rig hold the outer well pipe and press it down; the rotary drilling rig and the full-casing drilling rig are constructed alternately, excavating soil while sinking the outer well pipe with an inner diameter to the preset ground depth. In this technical solution, the outer well pipe is installed in a segmented manner. On the one hand, it reduces the transportation and construction difficulty, and on the other hand, the segmented installation method is convenient for combining the construction plan of advanced soil excavation and simultaneously pressing in the outer well pipe, improving the construction efficiency and being conducive to ensuring the verticality of the outer well pipe.

[0020] In a further solution, the outer diameter of the upper end portion of the outer pipe section is less than or equal to the inner diameter of the lower end portion, and a male thread and a female thread that are adapted to each other are provided on the inner wall of the upper end portion and the outer wall of the lower end portion of the outer pipe section; the lower end portion of the upper outer pipe section is sleeved on the upper end portion of the lower outer pipe section and locked based on the male thread and the female thread; and axial holes radially penetrating through the side walls are provided at both the upper end portion and the lower end portion of the outer pipe section; when two adjacent outer pipe sections are sleeved, the axial holes at the lower end portion of the upper outer pipe section correspond to the axial holes at the upper end portion of the lower outer pipe section, and a bolt assembly passes through the axial holes for locking. In this technical solution, two adjacent outer pipe sections are connected by a sleeving method; during sleeving, since the outer diameter of the upper end portion of the outer pipe section is less than or equal to the inner diameter of the lower end portion, rapid sleeving can be achieved, and locking is performed based on the male thread and the female thread during the sleeving process, and further, the connection strength is enhanced by a bolt assembly.

[0021] Preferably, during the advanced drilling of the bottom of the outer casing by a rotary drilling rig, mud needs to be injected into the outer casing, and the height of the upper end surface of the mud is not lower than the bottom of the outer casing. In this technical solution, the outer well pipe inside the outer casing is surrounded and protected by the outer casing, and the outer well pipe below the outer casing is under external pressure during the construction process. During this process, mud needs to be injected into the outer casing, and the height of the upper end surface of the mud is not lower than the bottom of the outer casing to ensure that the outer well pipe below the outer casing is not squeezed and deformed.

[0022] Preferably, in step 4, multiple sealing ring hoops are arranged above the bottom opening of the outer well pipe, and the bottom opening of the open outer well pipe is sealed by pouring expanded concrete to form an outer well pipe with a closed lower opening. In this solution, by using C35 self-compacting micro-expansion concrete for bottom sealing treatment, the compactness and impermeability are improved on the basis of facilitating construction.

[0023] Preferably, before installing the concrete conduit, the inner wall at a position 3 m above the bottom opening of the outer well pipe is cleaned to clean the attached soil on the inner wall; after the concrete pouring conduit is installed, air-lift reverse circulation is used for secondary hole cleaning; after pouring according to the requirements of underwater concrete until the concrete pouring is completed, after the concrete begins to set, the concrete floating slurry is taken out with a rotary drilling bucket, and the rotary drilling bucket is reversed to scrape the concrete surface flat to ensure the flatness of the bottom of the outer well pipe. In this solution, hole cleaning is performed twice before concrete pouring to ensure the connection strength between the concrete and the inner wall of the outer well pipe; after pouring is completed, the rotary drilling bucket is reversed to scrape the concrete surface flat to ensure the flatness of the bottom of the outer well pipe for installing the base.

[0024] Preferably, in step 6, the inner well pipe is hoisted in sections and butt-jointed with a flange at the orifice. A base is provided below the inner well pipe. When installing and lowering, it sinks along the inner wall of the outer well pipe by fitting the base, and together with the positioning blocks welded to the outer wall of the inner well pipe, the verticality is corrected in real time to ensure that the inner well pipe always remains at the center position of the outer well pipe and is installed in place. In this solution, the base at the lower end of the inner well pipe can stably support the inner well pipe, ensuring that the inner well pipe is centered relative to the outer well pipe and does not shake; during the process of installing the inner well pipe into the outer well pipe, the base and the positioning blocks on the side wall of the inner pipe section can keep the inner well pipe at the center of the outer well pipe and sink vertically, improving the installation accuracy of the inner well pipe.

[0025] In a specific solution, the base includes a central seat and a plurality of positioning plates arranged circumferentially along the central seat; the area enclosed by the plurality of positioning plates above the central seat constitutes the positioning groove; the circumferential positioning plates of the base are in contact with the inner wall of the outer well pipe, and the bottom of the innermost pipe section at the lowest end of the inner well pipe is installed in the positioning groove of the base. In the base of this solution, a plurality of positioning plates are arranged circumferentially along the central seat. The outer ends of the positioning plates are used to be in contact with the inner wall of the outer well pipe, and the positioning groove constructed by the inner enclosure is used to position the inner well pipe.

[0026] Further, a plurality of positioning pieces are arranged circumferentially on the outer side wall of each inner pipe section. When the inner pipe section is installed inside the outer well pipe, the radially outer ends of the positioning pieces are in contact with the inner wall of the outer well pipe; the positioning pieces are U-shaped pieces, the U-shaped openings of the positioning pieces face the inner pipe section, and the two U-shaped ends of the positioning pieces are welded and fixed to the outer side wall of the inner pipe section, and the radially outer ends of the U-shaped pieces are arc-shaped. In the technical solution of this positioning piece, the two U-shaped ends are welded to the outer side wall of the inner pipe section to ensure the connection strength; the outer ends of the U-shaped pieces are constructed into an arc shape to play a guiding role during the hoisting and centering process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a large-diameter steel pipe sleeve well involved in the present invention.

[0028] Figure 2 It is a schematic structural diagram of the base.

[0029] Figure 3 It is a partial schematic diagram of the inner well pipe.

[0030] Figure 4 It is a partial schematic diagram of the outer well pipe and its enlarged view.

[0031] Figure 5 It is a construction drawing for installing the outer casing in step 2.

[0032] Figure 6 It is a construction drawing for installing the outer well pipe in step 3.

[0033] Figure 7It is the construction drawing for pouring the bottom seal of the outer well pipe in Step 4.

[0034] Figure 8 It is the construction drawing for filling gravel and pulling out the outer casing in Step 5.

[0035] Figure 9 It is the construction drawing for installing the inner well pipe in Step 6. Detailed implementation manners

[0036] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0038] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more, unless otherwise clearly defined.

[0039] In the present invention, unless otherwise clearly specified and defined, the terms "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0041] This embodiment relates to an installation method for a large-diameter steel pipe sleeve well. The structure of the large-diameter steel pipe sleeve well constructed by this installation method is shown in the appendix Figures 1 to 4 A large-diameter steel pipe sleeve well shown, which includes an outer well pipe 1 and an inner well pipe 2 installed inside the outer diameter pipe.

[0042] As Figure 1 and 4 shown, the outer well pipe 1 includes multiple outer pipe segments 11 connected and fixed. The outer diameter of the upper end of the outer pipe segment 11 is less than or equal to the inner diameter of the lower end. A male buckle 12 and a female buckle 13 are provided on the inner wall of the upper end and the outer wall of the lower end of the outer pipe segment 11 respectively and are adapted to each other. The lower end of the upper outer pipe segment 11 is sleeved on the upper end of the lower outer pipe segment 11 and is locked based on the male buckle 12 and the female buckle 13. In this technical solution, the adjacent two outer pipe segments 11 are connected in a sleeved manner. During sleeving, since the outer diameter of the upper end of the outer pipe segment 11 is less than or equal to the inner diameter of the lower end, rapid sleeving can be achieved, and locking is performed based on the male buckle 12 and the female buckle 13 during the sleeving process. Both the upper end and the lower end of the outer pipe segment 11 are provided with axial holes 14 radially penetrating through its side wall. When two adjacent outer pipe segments 11 are sleeved, the axial holes 14 at the lower end of the upper outer pipe segment 11 correspond to the axial holes 14 at the upper end of the lower outer pipe segment 11, and a bolt assembly passes through the axial holes 14 for locking to enhance the connection strength based on the bolt assembly.

[0043] As Figure 1As shown, the outer well pipe 1 is a hollow pipe, and the bottom end of the outer well pipe 1 is cast with a bottom seal 10. This solution uses an open steel well pipe and the method of sinking and installing it in place before pouring the bottom seal 10, which reduces the difficulty of sinking a large-diameter bottom-sealed steel pipe well, improves the construction efficiency, and reduces the construction cost. Further shown in the figure, a base 3 is installed by sinking at the bottom of the outer well pipe 1, and the base 3 is arranged on the bottom seal 10 of the outer well pipe 1. The circumferential side wall of the base 3 is fitted with the inner wall of the outer well pipe 1, and a positioning groove 33 is provided at the center of the upper end of the base 3. In a specific implementation, the base 3 includes a central seat 31 and a plurality of positioning plates 32 arranged circumferentially along the central seat 31. The area enclosed by the plurality of positioning plates 32 above the central seat 31 forms the positioning groove 33. In the base 3 of this solution, a plurality of positioning plates 32 are arranged circumferentially around the central seat 31. The outer ends of the positioning plates 32 are used to fit with the inner wall of the outer well pipe 1, and the positioning groove 33 constructed by the inner enclosure is used to position the inner well pipe 2. In addition, the upper end portion of the inner wall of the positioning plate 32 is in an inclined shape 34, so that the upper end opening of the positioning groove 33 is in a tapered shape. In this solution, the upper end opening of the positioning groove 33 being in a tapered shape facilitates the inner well pipe 2 to be inserted into the positioning groove 33, and the tapered opening has a guiding effect during the insertion process.

[0044] As Figure 3 shown, the inner well pipe 2 includes a plurality of internally connected and fixed inner pipe segments 21. Adjacent two inner pipe segments 21 of the inner well pipe 2 are connected and fixed by flanges. The bottom of the lowermost inner pipe segment 21 of the inner well pipe 2 is installed in the positioning groove 33 of the base 3. A plurality of positioning pieces 22 are circumferentially arranged on the outer side wall of each inner pipe segment 21. When the inner pipe segment 21 is inserted into the inside of the outer well pipe 1. The radially outer end portion of the positioning piece 22 is fitted with the inner wall of the outer well pipe 1. The positioning piece 22 is a U-shaped piece, the U-shaped opening of the positioning piece 22 faces the inner pipe segment 21, and the two U-shaped ends of the positioning piece 22 are welded and fixed to the outer side wall of the inner pipe segment 21, and the radially outer end portion of the U-shaped piece is circular arc-shaped. In the technical solution, the U-shaped two ends of the positioning piece 22 are welded to the outer side wall of the inner pipe segment 21 to ensure the connection strength. The outer end portion of the U-shaped piece is constructed into a circular arc shape to play a guiding role during the hoisting and centering process.

[0045] Refer to the attached Figures 5 - 9 shown, the installation method of the large-diameter steel pipe sleeve well includes the following construction steps:

[0046] Step 1, construct a cofferdam in the selected area of the lake or river, and harden the riverbed within the cofferdam range.

[0047] Step 2: After the site hardening meets the standards, use a full casing pipe-rubbing drilling rig to drill holes at the predetermined locations. The center of the pipe gripper of the full casing drilling rig corresponds to the center of the hole position. The full casing pipe-rubbing drilling rig uses a φ4000mm jaw to clamp the first casing section 41 of the outer casing 4 and press it in, with a pressing depth of 2 - 3m, and adjust the verticality. Then start to use a hydraulic grab in the pipe to take soil. The pipe-rubbing drilling rig's jaw holds the casing section 41 and installs it in sections. A certain length needs to be reserved on the bottom surface for connecting the next casing section 41 when each casing section 41 is pressed into the soil. During the installation process of the casing section 41, correct the verticality of the outer casing 4 at any time, and ensure that the verticality is controlled within 2‰ until the lower end of the outer casing 4 reaches the underground preset depth [about 40m below the ground].

[0048] Step 3: The full casing pipe-rubbing drilling rig is combined with a rotary drilling rig to construct the outer well pipe 1. First, replace the φ4000mm jaw with a φ3320mm jaw for clamping the outer well pipe 1. The outer well pipe 1 includes multiple outer pipe sections 11 connected and fixed, and the bottom of the outer well pipe 1 is hollow. The adjacent two outer pipe sections 11 of the outer well pipe 1 are fixed and butt-jointed at the hole opening [connected by male and female buckle 13 bolts]. Before each outer pipe section 11 is installed into the outer casing 4, the next outer pipe section 11 needs to be connected and fixed; the jaw of the pipe-rubbing drilling rig holds the outer well pipe 1 and presses it down, and hoist and align the outer well pipe 1 to install it into the outer casing 4 until the bottom of the outer well pipe 1 reaches the bottom of the outer casing 4.

[0049] Before the rotary drilling rig advances ahead at the bottom of the outer casing 4, it is necessary to inject mud into the outer casing 4, and the height of the upper end surface of the mud is not lower than the bottom of the outer casing 4. In this scheme, the outer well pipe 1 inside the outer casing 4 is enclosed and protected by the outer casing 4. During the construction process of the outer well pipe 1 below the outer casing 4, it is under external pressure. During this process, it is necessary to inject mud into the outer casing 4, and the height of the upper end surface of the mud is not lower than the bottom of the outer casing 4 to ensure that the outer well pipe 1 below the outer casing 4 is not squeezed and deformed. The mud is pre-prepared before the rotary drilling rig drills. Bentonite and other additives are used to prepare the mud, and the preparation of the mud is stirred by a high-speed rotary mixer. For each unit of mud, 150 - 200kg of high-quality mud-making clay, 1000L of water, 5 - 10kg of soda ash, and about 6kg of Na-CMC (sodium carboxymethyl cellulose) are used. The properties of the mud are: density 1.07 - 1.1g / cm3, viscosity 25 - 35s, water loss less than 12ml / 30min, and pH value about 9.5. The mixing time of the mud shall not be less than 10min. The freshly mixed mud must be hydrated and decomposed in the mud pool for 24h and can be officially used only after passing the inspection.

[0050] Finally, a rotary drilling rig is used to advance soil extraction inside the outer casing 4 while pressing in the outer well pipe 1; the rotary drilling rig first drills ahead to a certain depth and then continues to hoist the outer well pipe 1 to the orifice for fixed butt-joint [connected by male-female buckle 13 bolts], and in this way, the outer well pipe 1 is hoisted in segments and centered and installed inside the outer casing 4. The rotary drilling rig and the full casing drilling rig are constructed alternately, and the outer well pipe 1 with an inner diameter is sunk to the preset depth on the ground [about 103 m below the ground] while extracting soil.

[0051] Step 4: Pour the bottom seal 10 at the bottom of the outer diameter pipe. After pressing the open outer well pipe 1 with an inner diameter of φ3200 mm to the bottom of the hole, in order to form the outer well pipe 1 with a closed lower end, it is necessary to pour C35 self-compacting slightly expanding concrete at the bottom opening of the open outer well pipe 1 for bottom seal 10 treatment; specifically, three sealing ring hoops are arranged above the bottom opening of the outer well pipe 1, and expanding concrete is poured at the bottom opening of the open outer well pipe 1 for bottom seal 10 treatment. The elevation of the bottom seal 10 is controlled within ±30 cm of the designed bottom elevation of the outer well pipe 1. After the bottom seal 10, the outer well pipe 1 is formed.

[0052] The specific process of the bottom seal 10 is as follows:

[0053] 1. Conduct a sealing effect test on the C35 self-compacting slightly expanding concrete until the requirements for the bottom seal 10 are met;

[0054] 2. Conduct a watertight test on the concrete pouring conduit 101 before installation.

[0055] 3. Before installing the concrete conduit, install a wire brush on the rotary drilling bucket, put the bucket into the bottom of the outer well pipe 1, and clean the inner wall at a position 3 m above the bottom opening of the outer well pipe 1 to clean the attached soil on the inner wall.

[0056] 4. Second hole cleaning by air-lift reverse circulation to remove sediment: After the concrete pouring conduit is installed, use air-lift reverse circulation for secondary hole cleaning. Before hole cleaning, measure and record the hole depth, compare it with the final hole depth, calculate that the sediment thickness should be ≤200 mm, and check whether various equipment such as the conduit, air pipe, air compressor, and sediment separation water pump is in good condition; lower the air supply pipe, and the air supply pipe is lowered to 1 / 3 of the hole depth. Connect the other end of the air supply pipe to the air compressor air pipe with a rubber pipe, connect the slag outlet to the slurry inlet of the sediment separator, and lead the slurry replenishing pipe to the orifice to ensure the mud level in the hole; start the air compressor for hole cleaning; after hole cleaning is completed, turn off the air compressor, remove the conduit cap, and pull out the air pipe.

[0057] 5. Before concrete pouring, the concrete in the tank truck must rotate at high speed for no less than 3 minutes before discharging. Visually inspect the workability of the concrete and the size of the coarse aggregate, conduct a slump test on the concrete. The underwater poured concrete must have good workability, and the slump should be 180 - 220 mm. Concrete that does not meet the requirements is not allowed to be poured, and the supervisor engineer should be notified to determine the treatment on-site.

[0058] 6. Based on factors such as pile diameter, pile hole depth, distance between the conduit and the bottom of the hole, buried depth of the conduit and height of concrete in the conduit, the first batch of concrete is calculated to be approximately 10m 3 .

[0059] 7. Pour according to the requirements of underwater concrete. A bladder must be placed in the conduit and an opener must be placed in the funnel. After discharge, the bladder overflows from the bottom of the hole along with a considerable amount of mud. The lower end of the conduit is buried in the concrete. Detect the height of the concrete surface at any time, calculate the depth of the lower end of the conduit buried in the concrete, and keep records.

[0060] 8. The height of the concrete surface in the hole should be detected at any time to calculate the buried depth of the conduit. After the concrete is poured, the conduit should be correctly commanded to be slowly lifted and removed.

[0061] 9. After the concrete has initially set, the concrete slurry is taken out with a rotary drilling bucket, and the drill bucket is reversed to scrape the concrete surface flat to ensure that the bottom of the outer well pipe 1 is flat.

[0062] Step 5: Within about 40m below the ground, the space between the outer casing 4 and the outer well pipe 1 is filled with gravel 51, and the outer casing 4 is pulled out while backfilling the gravel 51. A backfill protection cap 5 is set on the top of the outer well pipe 1 to prevent the gravel 51 from falling into the outer well pipe 1.

[0063] Step 6, the inner well pipe 2 is hoisted in sections, and flanges are used for docking at the openings. A base 3 is set under the inner well pipe 2. When it is installed and lowered, the base 3 is attached to the inner wall of the outer well pipe 1 and sinks, and cooperates with the positioning blocks welded on the outer wall of the inner well pipe 2 to correct the verticality in real time to ensure that the inner well pipe 2 always remains in the center of the outer well pipe 1 and is installed in place. In this step, the base 3 at the lower end of the inner well pipe 2 can stably support the inner well pipe 2, ensuring that the inner well pipe 2 is aligned with the center of the outer well pipe 1 and does not shake. In the process of the inner well pipe 2 being installed into the outer well pipe 1, the positioning blocks on the base 3 and the side walls of the inner pipe section 21 can keep the inner well pipe 2 in the center of the outer well pipe 1 and sink vertically, thereby improving the installation accuracy of the inner well pipe 2.

[0064] The present invention adopts the above technical solution, which relates to a method for installing a large-diameter steel pipe casing well. The installation method adopts the above steps and has at least the following advantages:

[0065] 1. The present invention replaces the existing method of pouring concrete by using a steel cage to directly press in the outer well pipe 1, thereby creating conditions for installing the inner and outer well pipes 1 underwater. Directly pressing in the outer well pipe 1 improves the construction efficiency compared to pouring concrete, and can adapt to different geologies and avoid the risk of hole collapse.

[0066] 2. The present invention reduces the difficulty of sinking a large-diameter steel well pipe with a bottom seal 10 by using an open steel well pipe, sinking it into place and then sealing the bottom 10, thereby improving construction efficiency and reducing construction costs.

[0067] 3. The present invention constructs a hole for the outer casing 4 with an outer diameter of φ4000mm by using a full casing pipe-rubbing drilling rig within about 40m below the ground surface, so as to reduce the frictional resistance during the sinking of the outer well pipe 1 with an inner diameter of φ3200mm, facilitate the smooth installation and sinking of the outer well pipe 1 with an inner diameter of φ3200mm, and ensure the verticality at the same time.

[0068] 4. The present invention advances the drilling by using a rotary drilling rig. Before the rotary drilling rig drills a hole, mud is pre-prepared [using bentonite and other additives to prepare the mud, and the mud is prepared by stirring with a high-speed rotary mixer], which can ensure the smooth construction of the outer well pipe 1 without deformation.

[0069] 5. The present invention adopts fixed butt joint at the hole opening [the outer well pipe 1 is connected by male and female joints 13 bolts], replacing the usual welding, improving the safety factor, avoiding the risk of weld compression deformation and leakage. During installation, the verticality is continuously corrected without interruption to improve the installation accuracy.

[0070] 6. The present invention conducts bottom sealing treatment 10 by pouring C35 self-compacting and slightly expanding concrete, which improves the compactness and impermeability on the basis of facilitating construction.

[0071] 7. The present invention is provided with a support base 3 and a positioning block at the bottom of the inner well pipe 2. When installing the inner well pipe 2, the base 3 can sink along the outer well pipe 1 continuously, so that the inner well pipe 2 always remains at the center of the outer well pipe 1 and sinks vertically, improving the installation accuracy of the inner well pipe 2.

[0072] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0073] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A method for installing a large-diameter steel pipe casing well, characterized in that: It includes the following construction steps: Step 1: Construct a cofferdam in the selected area of the lake or river course, and harden the riverbed within the cofferdam range; Step 2: After the site hardening meets the standard, use a full casing pipe-rubbing drilling rig to drill holes at the predetermined locations. The center of the pipe gripper of the full casing drilling rig corresponds to the center of the hole position. After calibrating the outer casing (4), install it into the hole. The lower end of the outer casing (4) reaches the preset underground depth, and the upper end of the outer casing (4) extends out of the ground; Step 3: Use the full casing pipe-rubbing drilling rig in combination with a rotary drilling rig to construct the outer well pipe (1). The bottom of the outer well pipe (1) is hollow. First, hoist and align the outer well pipe (1) and install it into the outer casing (4) until the bottom of the outer well pipe (1) reaches the bottom of the outer casing (4). Then, use a rotary drilling rig to advance soil extraction in the outer casing (4) while pressing the outer well pipe (1) into it, and cycle the construction until the preset underground depth; Step 4: Pour a bottom seal (10) at the bottom of the outer well pipe; Step 5: Set a backfill protection cap (5) at the top of the outer well pipe (1). Fill the space between the outer casing (4) and the outer well pipe (1) with gravel (51), and pull out the outer casing (4) while backfilling the gravel (51); Step 6: Set a base (3) below the inner well pipe (2). During installation and lowering, it sinks along the inner wall of the outer well pipe (1) by fitting the base (3), and cooperate with the positioning blocks welded on the outer wall of the inner well pipe (2) to correct the verticality in real time to ensure that the inner well pipe (2) always remains in the central position of the outer well pipe (1) and is installed in place. Hoist and install the inner well pipe (2) in sections into the outer well pipe (1) to ensure that the inner well pipe (2) always remains in the central position of the outer well pipe (1) and is installed in place.

2. The installation method of a large-diameter steel pipe socket well according to claim 1, characterized in that: In Step 2: The outer casing (4) includes multiple connected and fixed casing sections (41). The rotary drilling rig first advances soil extraction at the predetermined location. The pipe-rubbing drilling rig's jaws hold the casing section (41) and install it in sections. A certain length needs to be reserved on the bottom surface for each section of the casing section (41) pressed into the soil to connect the next section of the casing section (41). During the installation process of the casing section (41), the verticality of the outer casing (4) is corrected at any time, and it is necessary to ensure that the verticality is controlled within 2‰ until the lower end of the outer casing (4) reaches the preset underground depth.

3. The installation method of a large-diameter steel pipe sleeve well according to claim 1, characterized in that: In Step 3, the outer well pipe (1) includes multiple connected and fixed outer pipe sections (11). The outer well pipe (1) is hoisted and aligned in sections and installed into the outer casing (4). Before each section of the outer pipe section (11) is installed into the outer casing (4), the next section of the outer pipe section (11) needs to be connected and fixed. The jaws of the pipe-rubbing drilling rig hold the outer well pipe (1) and press it down; the rotary drilling rig and the full casing drilling rig are constructed alternately, and the inner diameter outer well pipe (1) is sunk to the preset ground depth while extracting soil.

4. A method for installing a large-diameter steel pipe sleeve well according to claim 3, characterized in that: The outer diameter of the upper end portion of the outer pipe section (11) is less than or equal to the inner diameter of the lower end portion. A male thread (12) and a female thread (13) that are adapted to each other are provided on the inner wall of the upper end portion and the outer wall of the lower end portion of the outer pipe section (11); the lower end portion of the upper outer pipe section (11) is sleeved on the upper end portion of the lower outer pipe section (11) and is locked based on the male thread (12) and the female thread (13); and, axial holes (14) that radially penetrate the side wall are provided at both the upper end portion and the lower end portion of the outer pipe section (11); when two adjacent outer pipe sections (11) are sleeved, the axial holes (14) at the lower end portion of the upper outer pipe section (11) correspond to the axial holes (14) at the upper end portion of the lower outer pipe section (11), and a bolt assembly passes through the axial holes (14) for locking.

5. The installation method of a large-diameter steel pipe sleeve well according to claim 3, characterized in that: During the advanced drilling process of the bottom of the outer casing (4) by the rotary drilling rig, it is necessary to inject mud into the outer casing (4), and the height of the upper end surface of the mud is not lower than the bottom of the outer casing (4).

6. The installation method of a large-diameter steel pipe sleeve well according to claim 1, characterized in that: In step 4, a plurality of sealing ring hoops are provided above the bottom opening of the outer well pipe (1), and the bottom opening of the open outer well pipe (1) is filled with expanded concrete for bottom sealing (10) treatment to form an outer well pipe (1) with a closed lower opening.

7. The installation method of a large-diameter steel pipe sleeve well according to claim 6, characterized in that: Before installing the concrete conduit, the inner wall at a position 3 m above the bottom opening of the outer well pipe (1) is cleaned to clean the attached soil on the inner wall; after the concrete pouring conduit is installed, air-lift reverse circulation is used for secondary hole cleaning; after pouring according to the requirements of underwater concrete until the concrete pouring is completed, when the concrete begins to set, the floating slurry of the concrete is taken out with a rotary drilling bucket, and the concrete surface is scraped flat by using the reverse rotation of the bucket to ensure the flatness of the bottom of the outer well pipe (1).

8. The installation method of a large-diameter steel pipe socket well according to claim 1, characterized in that: In step 6, the inner well pipe (2) is hoisted in sections and butt-jointed with a flange at the hole opening.

9. The installation method of a large-diameter steel pipe sleeve well according to claim 8, characterized in that: The base (3) includes a central seat (31) and a plurality of positioning plates (32) arranged circumferentially along the central seat (31); the area enclosed by the plurality of positioning plates (32) above the central seat (31) forms a positioning groove (33); the circumferential positioning plates (32) of the base (3) are attached to the inner wall of the outer well pipe (1), and the bottom of the lowermost inner pipe section (21) of the inner well pipe (2) is installed in the positioning groove (33) of the base (3).

10. A method for installing a large-diameter steel pipe casing well according to claim 8, characterized in that: A plurality of positioning pieces (22) are circumferentially arranged on the outer side wall of each inner pipe section (21); when the inner pipe section (21) is installed inside the outer well pipe (1); the radially outer end portion of the positioning piece (22) is attached to the inner wall of the outer well pipe (1); the positioning piece (22) is a U-shaped piece, the U-shaped opening of the positioning piece (22) faces the inner pipe section (21), and the two U-shaped end portions of the positioning piece (22) are welded and fixed to the outer side wall of the inner pipe section (21), and the radially outer end portion of the U-shaped piece is arc-shaped.

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