A construction method for reinforcing a wellhead

Abstract

This invention discloses a construction method for reinforcing the end of a starting well, comprising the following steps: S1, after the construction of the working well structure is completed, the reserved openings on the left and right sides are sealed, with sealing divided into sealing within the jacking range and sealing within the grouting range outside the jacking range; S2, a prefabricated intermediate jacking pipe is constructed, with grouting holes drilled around its perimeter; S3, within the reserved grouting range outside the jacking range, a first layer of annular H-beams and a second layer of annular H-beams are installed sequentially from the inside out, with holes drilled in the webs of the first and second layers of annular H-beams as guide holes for the intermediate jacking pipe construction, and the prefabricated intermediate jacking pipe is inserted into the guide holes; S4, a grout-stopping wall is formed; S5, a PVC pipe is inserted into the intermediate jacking pipe, and grout is injected into the grouting holes of the intermediate jacking pipe. This invention, under limited conditions, uses intermediate jacking pipe grouting requiring only cement slurry and a small amount of seamless steel pipe, without additional project investment, resulting in lower costs, and exhibiting high efficiency, feasibility, and safety.

Description

Technical Field

[0001] This invention relates to the field of wellhead reinforcement. More specifically, this invention relates to a construction method for wellhead reinforcement. Background Technology

[0002] With the development and utilization of underground space, pipe jacking engineering, as a non-cut-and-cover technology, has also developed rapidly. During the construction of pipe jacking projects, surface deformation and settlement are prone to occur at the initiation and reception of the pipe, especially when the end reinforcement fails to meet the design requirements or fails, which can easily lead to safety accidents.

[0003] A parallel twin-tunnel jacking project with a small clearance traverses a layer of gravelly clay and silty mudstone with a high permeability coefficient. The jacking also passes under an existing river, with the riverbank only 3 meters from the starting shaft end. The working face will be open during the initial jacking operation, and this open state will persist for a considerable period. Improper handling could allow groundwater, sand inrush, and water inrush to enter the working shaft, potentially causing a collapse of the tunnel portal. Therefore, end reinforcement is extremely important in pipe jacking construction. Existing end reinforcement methods typically include two approaches: one is to install jet grouting piles within a certain range at the starting shaft end, followed by the addition of diaphragm walls at the edge for sealing and reinforcement; the other is to use sleeve valve grouting when passing under existing pipelines or structures, achieving reinforcement through proper spacing and row spacing of the sleeve valves. However, given that the jacking passes under an existing river and the starting shaft end is only 3 meters from the riverbank, it is not feasible to reinforce the starting shaft end using jet grouting piles and sleeve valve grouting on the ground surface.

[0004] Therefore, in view of the problems existing in the above-mentioned technologies, there is an urgent need for a new method for reinforcing the starting wellhead. This method can not only overcome the limitations of existing construction conditions and achieve a significant reinforcement effect, and solve the technical risks of pipe jacking in the initial stage, but also meet the requirements of safety, economy, environmental protection, applicability, and high efficiency. Summary of the Invention

[0005] To achieve these objectives and other advantages according to the invention, a preferred embodiment of the invention provides a construction method for reinforcing the tip of a starting well, comprising the following steps:

[0006] S1. After the construction of the working well structure is completed, the reserved openings on the left and right sides will be sealed. The sealing will be divided into sealing within the jacking range and sealing within the grouting range outside the jacking range.

[0007] S2, precast intermediate shed pipe, with grouting holes drilled around its perimeter;

[0008] S3. Install the first layer of annular H-beams and the second layer of annular H-beams from the inside out within the grouting range reserved on the outside of the jacking pipe. Make holes in the webs of the first layer of annular H-beams and the second layer of annular H-beams as guide holes for the construction of the middle shed pipe, and insert the prefabricated middle shed pipe into the guide holes.

[0009] S4. After the middle shed pipe is inserted, further construction is carried out to form a grout stop wall. The grout stop wall inside the jacking pipe is made of brick masonry, while the grout stop wall outside the jacking pipe is made by spraying concrete onto the first and second ring-shaped I-beams.

[0010] S5. Insert a PVC pipe into the middle shed pipe, weld the middle shed pipe shut with a cover plate and iron hoops, inject grouting material into the grouting hole of the middle shed pipe through the grouting pipe, and discharge the overflowing grouting material through the grout outlet pipe, thereby completing all grouting.

[0011] Preferably, in S1, the sealing within the jacking range is achieved by full brick masonry sealing, and the well opening is reinforced and supported by cross-shaped I-beams; the reserved opening is sealed by spraying waterproof concrete within the grouting range outside the jacking range, and the waterproof concrete also contains a first layer of annular I-beams and a second layer of annular I-beams.

[0012] Preferably, the grouting holes on the intermediate shed pipe are multiple and arranged in a quincunx pattern. The tail of the intermediate shed pipe has a stop section that is not drilled, and the pipe head of the intermediate shed pipe is welded into a closed cone to facilitate insertion into the hole.

[0013] Preferably, in step S3, the guide hole diameter is 108mm, the drilling depth is 12m, the circumferential distance between two adjacent guide holes is 30cm, and the guide holes are marked with red paint to distinguish between odd-numbered and even-numbered holes, wherein a down-the-hole drill is used for drilling.

[0014] Preferably, diaphragm pressure gauges are installed in the grout inlet pipe and the grout outlet pipe to form a complete pressure monitoring system and control the grouting pressure.

[0015] Preferably, the grouting material is injected using a three-cylinder split-type geared grouting machine with a grouting flow rate of 250L / min, which can still provide a pressure of 2.5MPa when the grouting volume is at its maximum.

[0016] Preferably, in step S5, grouting proceeds from low to high. After grout flows out of the vent hole, the vent hole is closed and a pressure gauge is installed. First, a 52L / min setting is used for double-hole grouting, with the grouting pressure controlled at 0.2-0.4MPa. After two hours, grouting is performed at a 90L / min setting until the target grouting pressure is controlled at 0.8-1MPa. During the grouting process, two holes are treated as a group, and grouting is performed in a cycle at 52L / min and 90L / min settings until the reinforcement requirements are met.

[0017] Preferably, during the grouting process, all vent valves and grouting valves of the grouting holes should be opened to release air. If cracks or grout leakage occur in the stop wall, grouting should be stopped first, and the stop wall should be re-sprayed with concrete or sealed with anchoring agent. Grouting can continue after the re-sprayed concrete or anchoring agent has solidified.

[0018] The present invention has at least the following beneficial effects:

[0019] 1) Economic efficiency: Under limited conditions, the use of medium-span pipe grouting only requires cement grout and a small amount of seamless steel pipe, without the need for additional project investment, and the cost is low.

[0020] 2) High efficiency: Using the dual-hole grouting method for the middle shed pipe, grouting can be completed in two speed settings: 52L / min and 90L / min. Each speed setting takes 2 hours to complete the grouting of one middle shed pipe, which is time-saving and efficient.

[0021] 3) Safety: After the grouting reinforcement of the middle jacking pipe, no sand or water inrush occurred during the jacking process, and the settlement was controllable.

[0022] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 This is a structural distribution diagram of the initial wellhead reinforcement construction process in this invention.

[0024] Attached drawings: 1. Left reserved opening; 2. Right reserved opening; 3. Brick wall; 4. Cross-shaped I-beam; 5. Waterproof concrete layer; 6. First layer of ring-shaped I-beam; 7. Second layer of ring-shaped I-beam; 8. Middle shed pipe; 9. Grouting hole; 10. Reserved stop section; 11. Cone head; 12. Outer guide hole; 13. Inner guide hole; 14. PVC pipe; 15. Cover plate; 16. Iron hoop. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0026] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0027] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0028] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0029] like Figure 1 As shown, a preferred embodiment of the present invention provides a construction method for reinforcing the tip of a starting well, comprising the following steps:

[0030] S1. After the construction of the working well structure is completed, the reserved opening 1 on the left and the reserved opening 2 on the right will be sealed. The sealing is divided into sealing within the jacking range and sealing within the grouting range outside the jacking range.

[0031] In S1, the sealing within the jacking range is achieved by fully sealing with brick masonry wall 3, and the well opening is reinforced and supported with cross-shaped I-beams 4; the reserved opening is sealed with waterproof concrete sprayed within the grouting range outside the jacking range, and the waterproof concrete also contains a first layer of annular I-beams 6 and a second layer of annular I-beams 7.

[0032] S2, precast intermediate shed pipe 8, with grouting holes 9 drilled around its perimeter;

[0033] The grouting holes 9 are multiple and arranged in a quincunx pattern. The tail of the middle shed pipe 8 has a non-drilled stop section 10. The pipe head of the middle shed pipe 8 is welded into a closed cone 11 for easy insertion into the hole.

[0034] S3. Install the first layer of annular I-beams 6 and the second layer of annular I-beams 7 sequentially from the inside to the outside within the grouting range reserved on the outside of the jacking pipe. Make holes at the web of the first layer of annular I-beams 6 and the second layer of annular I-beams 7 as the outer guide hole 12 and the inner guide hole 13 for the construction of the middle shed pipe. Insert the prefabricated middle shed pipe 8 into the outer guide hole 12 and the inner guide hole 13.

[0035] After the middle shed pipe 8 is inserted into S4, further construction is carried out to form a grout-stopping wall. The grout-stopping wall inside the jacking pipe is composed of a brick wall 3, while the grout-stopping wall outside the jacking pipe is formed by spraying concrete onto the first layer of annular H-beams 6 and the second layer of annular H-beams 7. The thickness of the concrete is flush with that of the brick wall, forming a waterproof concrete layer 5 with a thickness of 80cm. The grout-stopping wall inside the jacking pipe was completed when sealing the reserved opening, and the grout-stopping wall outside the jacking pipe is formed by spraying an additional 60cm of concrete on top of the previous 20cm of sprayed concrete.

[0036] S5. Insert PVC pipe 14 into the middle shed pipe 8. PVC pipe 14 ensures that the grout flows from end to end. Weld the open end of the middle shed pipe closed with cover plate 15 and iron hoop 16 to prevent soil from entering the pipe through the opening later. Use grouting pipe to inject grouting material into the grouting hole 9 of the middle shed pipe 8, and use grout outlet pipe to discharge the overflowing grouting material, thereby completing all grouting.

[0037] The grouting material is cement grout with a water-cement ratio of 0.8:1.

[0038] In another technical solution, in S3, the diameter of the guide hole is 108mm, the drilling depth is 12m, the circumferential distance between two adjacent guide holes is 30cm, and guide holes 12 and 13 are marked with red paint to indicate odd-numbered holes and even-numbered holes, wherein a down-the-hole drill is used for drilling.

[0039] In another technical solution, diaphragm pressure gauges are installed in the grout inlet pipe and the grout outlet pipe to form a complete pressure monitoring system and control the grouting pressure.

[0040] In another technical solution, the grouting of the grouting material is carried out using a three-cylinder split-type geared grouting machine with a grouting flow rate of 250L / min, which can still provide a pressure of 2.5MPa when the grouting volume is at its maximum.

[0041] In another technical solution, in step S5, grouting proceeds from low to high. After grout flows out of the vent hole, the vent hole is closed and a pressure gauge is installed. First, a 52L / min setting is used for double-hole grouting, with the grouting pressure controlled at 0.2-0.4MPa. After two hours, grouting is performed at a 90L / min setting until the target grouting pressure is controlled at 0.8-1MPa. During the grouting process, two holes form a group, and grouting is performed in sequence at 52L / min and 90L / min settings until the reinforcement requirements are met. The vent hole is located on the middle shed pipe and at the end of the middle shed pipe.

[0042] In another technical solution, during the grouting process, all vent valves and grouting valves of the grouting holes should be opened to release air. If cracks or grout leakage occur in the stop wall, grouting should be stopped first, and the stop wall should be re-sprayed with concrete or sealed with anchoring agent. Grouting can continue after the re-sprayed concrete or anchoring agent has solidified.

[0043] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A construction method for reinforcing the tip of a starting well, characterized in that, Includes the following steps: S1. After the construction of the working well structure is completed, the reserved openings on the left and right sides will be sealed. The sealing will be divided into sealing within the jacking range and sealing within the grouting range outside the jacking range. S2, precast intermediate shed pipe, with grouting holes drilled around its perimeter; S3. Install the first layer of annular H-beams and the second layer of annular H-beams from the inside out within the grouting range reserved on the outside of the jacking pipe. Make holes in the webs of the first layer of annular H-beams and the second layer of annular H-beams as guide holes for the construction of the middle shed pipe, and insert the prefabricated middle shed pipe into the guide holes. S4. After the middle shed pipe is inserted, further construction is carried out to form a grout-stopping wall. The grout-stopping wall inside the jacking pipe is made of brick masonry, while the grout-stopping wall outside the jacking pipe is obtained by spraying concrete onto the first and second ring-shaped I-beams. S5. Insert a PVC pipe into the middle shed pipe, weld the middle shed pipe shut with a cover plate and iron hoops, inject grouting material into the grouting hole of the middle shed pipe through the grouting pipe, and discharge the overflowing grouting material through the grout outlet pipe, thereby completing all grouting.

2. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, In S1, the sealing within the jacking range is achieved by full brick masonry, and the well opening is reinforced and supported by cross-shaped I-beams; the reserved opening is sealed by spraying waterproof concrete within the grouting range outside the jacking range, and the waterproof concrete also contains a first layer of annular I-beams and a second layer of annular I-beams.

3. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, The grouting holes on the middle shed pipe are arranged in a quincunx pattern. The tail of the middle shed pipe has a non-drilled grout-stopping section. The pipe head of the middle shed pipe is welded into a closed cone for easy insertion into the hole.

4. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, In S3, the guide hole diameter is 108mm, the drilling depth is 12m, the circumferential distance between two adjacent guide holes is 30cm, and the guide holes are marked with red paint to distinguish between odd-numbered and even-numbered holes. Drilling is performed using a down-the-hole drill.

5. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, Diaphragm pressure gauges are installed in the grout inlet and outlet pipes to form a complete pressure monitoring system and control the grouting pressure.

6. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, The grouting of the grouting material is carried out using a three-cylinder split-type geared grouting machine with a grouting flow rate of 250L / min. Even when the grouting volume is at its maximum, it can still provide a pressure of 2.5MPa.

7. The construction method for reinforcing the starting well tip according to claim 6, characterized in that, In step S5, grouting proceeds from low to high. After grout flows out of the vent hole, the vent hole is closed and a pressure gauge is installed. First, a 52L / min setting is used for double-hole grouting, with the grouting pressure controlled at 0.2-0.4MPa. After two hours, grouting is performed at a 90L / min setting until the target grouting pressure is controlled at 0.8-1MPa. During the grouting process, two holes are treated as a group, and grouting is carried out in a cycle at 52L / min and 90L / min settings until the reinforcement requirements are met.

8. The construction method for reinforcing the starting well tip according to claim 1, characterized in that, During the grouting process, all vent valves and grouting valves of the grouting holes should be opened to release air. If any cracks or leakage occur in the grout stop wall, grouting should be stopped first, and the grout stop wall should be re-sprayed with concrete or sealed with anchoring agent. Grouting can continue after the re-sprayed concrete or anchoring agent has solidified.

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