Bidirectional grouting process by using freezing pipe

Abstract

The invention relates to the technical field of stratum freezing, in particular to a bidirectional grouting process utilizing a freezing pipe. Comprising the steps that (1) a grouting head is connected with a grouting device, and the grouting device is connected with a freezing pipe in a freezing hole; (2) a grouting pump communicated with the grouting head is started, grouting is conducted in the freezing pipe through a grouting device, and grout flows into a far-end stratum where the freezing hole is located and a gap between the freezing pipe and the freezing hole along the freezing pipe; (3) after grouting of the far-end stratum where the freezing hole is located is completed, the interior of the freezing pipe is cleaned; (4) a discharge port in the cleaned freezing pipe is blocked; 5, grout is injected into the gap between the freezing pipe and the freezing hole through a grouting device, the grout flows into the near-end stratum where the freezing hole is located, and the anti-seepage curtain is formed in the circumferential stratum of the freezing hole. According to the technology, bidirectional grouting improvement is conducted on the circumferential stratum of the freezing hole, the stratum gap can be filled, the stratum permeability coefficient can be changed, and the anti-seepage curtain is formed.

Description

Technical Field

[0001] This invention relates to the field of ground freezing technology, and more particularly to a bidirectional grouting process using freezing pipes. Background Technology

[0002] Soil rich in sand has low natural strength and high compressibility, making it prone to deformation and failure under high water pressure. Conventional grouting methods are insufficient to significantly improve the shear strength and elastic modulus of the soil, and the bearing capacity of the improved soil cannot meet the stability requirements of engineering projects such as tunnel excavation. Furthermore, uneven grouting can lead to uneven stress distribution in the soil, causing localized settlement or heave, and affecting the structural safety of the project. Therefore, a solution is urgently needed. Summary of the Invention The present invention addresses the aforementioned technical problem by providing a bidirectional grouting process using freezing pipes. This process improves the formation by bidirectional grouting around the circumference of the freezing holes, filling formation gaps, altering the formation permeability coefficient, and forming a seepage barrier.

[0003] A bidirectional grouting process utilizing freezing pipes includes the following steps: 1) Connect the grouting head to the grouting device, and connect the grouting device to the freezing pipe inside the freezing hole; 2) Turn on the grouting pump connected to the grouting head and inject grout into the freezing pipe through the grouting device. The grout flows along the freezing pipe into the stratum at the far end where the freezing hole is located and into the gap between the freezing pipe and the freezing hole. During the grouting process, observe the grouting pressure through the pressure gauge on the grouting head. Stop grouting if the pressure exceeds the design pressure value. 3) After the grouting of the stratum at the far end where the freezing hole is located is completed, the inside of the freezing pipe is cleaned until the cement slurry inside the freezing pipe is cleaned by using an endoscope and then the cleaning is stopped. 4) Seal the outlet of the cleaned freezing pipe; 5) Grout is injected into the gap between the freezing pipe and the freezing hole through the grouting device. The grout flows into the stratum near the freezing hole and forms a seepage barrier in the stratum around the freezing hole. During the grouting process, the grouting pressure is observed through the pressure gauge on the grouting head. Grouting is stopped when the pressure exceeds the design pressure value.

[0004] Preferably, the grouting device includes a sealing part and a grouting part; the advancing end of the freezing pipe passes through the shield shell and is connected to the drill bit used to drill the freezing hole; the sealing part is connected to the shield shell and is fitted over the outside of the freezing pipe to seal the gap between the freezing pipe and the shield shell; the grouting part is installed on the freezing pipe and the sealing part and is used to grout the circumferential strata of the freezing hole along the freezing pipe or the gap between the freezing pipe and the shield shell.

[0005] Preferably, the sealing part includes a sealing box sleeve, a sealing box tube, a ball valve, and an orifice tube, all fitted onto the freezing pipe; one end of the orifice tube is connected to the shield shell, and the other end is connected to the ball valve; the other end of the ball valve is connected to one end of the sealing box tube; the sealing box sleeve is used to seal the other end of the sealing box tube.

[0006] Preferably, the grouting section includes a grouting ball valve, a bypass ball valve, and a sealing element; the grouting ball valve is connected to a distal grouting joint installed at the feed end of the freezing pipe; the bypass ball valve is installed on the orifice pipe and is connected to the proximal grout outlet between the freezing pipe and the shield shell; the sealing element is installed at the discharge port of the freezing pipe and is used to open or block the discharge port of the freezing pipe.

[0007] Preferably, the sealing component includes a one-way valve plug and a one-way valve; the one-way valve is provided with a remote slurry outlet; the one-way valve plug is used to seal the remote slurry outlet and forms a threaded connection with the one-way valve.

[0008] Preferably, a first flange is provided between the sealing box sleeve and the freezing tube.

[0009] Preferably, a second flange for connection is provided between the sealing box sleeve and the sealing box tube, and tallow packing is filled between the sealing box tube and the freezing tube.

[0010] Preferably, a third flange for connection and a sealing ring for sealing are provided between the sealing box tube and the ball valve.

[0011] Preferably, a fourth flange for connection is provided between the ball valve and the orifice pipe.

[0012] The beneficial effects of this invention are reflected in: (1) The process provided by the present invention improves the formation by bidirectional grouting through the circumferential direction of the freezing hole, which can fill the gap between the formations, change the formation permeability coefficient, form a seepage prevention curtain, thereby reducing the groundwater flow velocity, which helps the formation of the freezing curtain, and is also beneficial to the control of formation frost heave and thaw settlement.

[0013] (2) The process provided by the present invention can improve the soil around the freezing hole. Traditional grouting is injected in one direction, resulting in uneven soil reinforcement. However, the bidirectional soil grouting of this application is injected from two directions, resulting in more uniform grout distribution. It can fill the soil pores and cracks in all directions, making the soil more isotropic and significantly improving the overall strength and stability.

[0014] (3) The process provided by the present invention can improve the freezing effect of the freezing hole, and the bidirectional grouting can accurately control the grout distribution, strengthen the strata, and create a more stable environment for freezing. It reduces the defects of the freezing wall caused by uneven soil and groundwater flow during the freezing process, and improves the strength and sealing of the freezing wall.

[0015] (4) The process provided by the present invention can fill the voids in the soil more quickly and comprehensively through bidirectional grouting, replenish the soil loss in time, and reduce the deformation and settlement caused by soil voids or loss. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the grouting device of the present invention.

[0017] Figure labels and descriptions: 1. Grouting ball valve; 2. Remote grouting joint; 3. Freezing pipe; 4. First flange; 6. Second flange; 8. Sealing box sleeve; 9. Sealing box tube; 10. Butter packing; 11. Connecting ball valve; 13. Third flange; 15. Shield ring; 16. Fourth flange; 18. Bypass ball valve; 21. Orifice pipe; 23. Shield shell; 24. Near-end grout outlet; 25. Check valve plug; 26. Check valve; 27. Remote grout outlet; 28. Drill bit. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example like Figure 1 As shown, the present invention provides a bidirectional grouting process using a freezing pipe, which includes the following steps: Grouting construction is carried out using the frozen pipe 3 that has been driven to the design depth. According to the construction process of the frozen pipe 3, after the depth of the frozen pipe 3 is re-measured and meets the design requirements, and before the grouting of the orifice pipe, the grouting and cleaning construction using the frozen pipe 3 are carried out in sequence.

[0020] Step 1: After the drilling depth of the freezing pipe 3 reaches the designed depth, connect the far end grouting joint 2 to the freezing pipe 3 via threads.

[0021] Step 2: Connect the mud pump grouting hose to grouting ball valve 1.

[0022] Step 3: The pumped cement grout is introduced into the freezing pipe 3 through the grouting ball valve 1. The cement grout enters the far-end stratum of the freezing hole through the grout outlet 27 of the one-way valve 26 (the one-way valve plug 25 is not installed at this time). The cement grout fills the gaps in the stratum and improves the soil properties.

[0023] In practical applications, the cement grout mix ratio can be slightly higher than that of the cement grout used for soil reinforcement, such as a water-cement ratio range of 0.8:1 to 2:1. Depending on the geological conditions, the grout can be made thinner first and then thicker, thereby expanding the grouting radius to the far-end bottom layer.

[0024] The grouting pressure can be stopped when it reaches 1.5 to 3 times the pressure of the original stratum or a safe pressure value that the nearby structure can withstand.

[0025] Step 4: Remove grouting joint 2.

[0026] Step 5: Connect the high-pressure hose to the mud pump (such as a BW250 mud pump) and push it through the freezing pipe 3 to the one-way valve 26. During this process, supply high-pressure clean water to clean the cement slurry and particles inside the freezing pipe 3. After cleaning, pull out the high-pressure hose. The flushing is complete when the water flowing out of the freezing pipe 3 is clear.

[0027] Step 6: Insert the endoscope probe into the freezing tube 3 to the one-way valve 26 position, and check if there are any uncleaned particles on the threads at the end of the one-way valve 26. Ensure that the freezing tube 3 is clean and free of particles.

[0028] Step 7: Use the threaded drill rod to push the 25 check valve plug to the check valve 26 position, and then tighten the 25 check valve plug to ensure that the check valve 26 thread is sealed, so that the freezing pipe 3 no longer communicates with the distant formation water.

[0029] Step 8: Connect the mud pump grouting hose to the bypass ball valve 18.

[0030] Step 9: The pumped cement grout is introduced through the bypass ball valve 18 into the orifice pipe 21, the near-end grout outlet 24, and then into the annular space between the freezing pipe 3 and the freezing hole. That is, the grout enters the near-end formation around the freezing hole from the near-end grout outlet 24. The grout mix ratio is the same as in Step 3. Grouting is stopped when the grouting pressure reaches 1.5 to 2 times the original formation pressure or a safe pressure value that the nearby structure can withstand.

[0031] Step 10: Close the bypass ball valve 18 and remove the mud pump grouting hose.

[0032] The technology provided in this application was used in an underwater docking and freezing project for a shield tunnel on the Yangtze River. During construction, the aforementioned technology was strictly followed. In high water pressure and sand-rich layers, bidirectional grouting effectively improved the strata, resulting in a well-formed freezing curtain and good control of frost heave. The successful implementation of this project provided invaluable experience for similar projects in the future and yielded the following economic benefits: 1.1 Reduce material waste: Two-way grouting can reinforce the soil more evenly. Compared with one-way grouting, it can precisely control the distribution of grout, reduce waste caused by excessive or uneven grout injection, and lower material costs.

[0033] 1.2 Reduce the cost of handling defects in frozen walls: Improve the quality of frozen walls, reduce problems such as leakage and deformation caused by defects, and avoid the cost of later repair and reinforcement, such as reducing the cost of local reinforcement grouting or refreezing of frozen walls.

[0034] 1.3 Reduce engineering risk costs: Ensure the freezing effect and reduce the risk of engineering accidents caused by freezing problems, such as avoiding water and sand inrush during tunnel freezing construction, and reducing losses caused by accident handling and delays.

[0035] 1.4 Reduce the cost of treating uneven settlement: It can accurately control settlement and adjust the grouting parameters for uneven settlement sections. Compared with traditional methods, it is more economical and efficient in treating uneven settlement and reduces the cost of subsequent uneven settlement treatment.

[0036] The bidirectional grouting technology provided in this application will have a wider application scope in urban underground space development projects that require freezing construction, such as deep foundation pit excavation and shield tunnel launching and receiving.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bidirectional grouting process utilizing freezing pipes, characterized in that, Includes the following steps: 1) Connect the grouting head to the grouting device, and connect the grouting device to the freezing pipe (3) inside the freezing hole; 2) Turn on the grouting pump connected to the grouting head and inject grout into the freezing pipe (3) through the grouting device. The grout flows along the freezing pipe (3) into the stratum at the far end where the freezing hole is located and into the gap between the freezing pipe (3) and the freezing hole. During the grouting process, observe the grouting pressure through the pressure gauge on the grouting head. Stop grouting if the pressure exceeds the design pressure value. 3) After the grouting of the stratum at the far end where the freezing hole is located is completed, the inside of the freezing tube (3) is cleaned until the cement slurry inside the freezing tube (3) is cleaned by using an endoscope and then the cleaning is stopped. 4) Seal the outlet of the cleaned freezing tube (3); 5) The grout is injected into the gap between the freezing pipe (3) and the freezing hole through the grouting device. The grout flows into the near-end stratum where the freezing hole is located. During the grouting process, the grouting pressure is observed through the pressure gauge on the grouting head. Grouting is stopped if the design pressure value is exceeded.

2. The bidirectional grouting process using a freezing pipe according to claim 1, characterized in that, The grouting device includes a sealing part and a grouting part; the advancing end of the freezing pipe (3) passes through the shield shell (23) and is connected to the drill bit (28) used to drill the freezing hole; the sealing part is connected to the shield shell (23) and is fitted on the outside of the freezing pipe (3) to seal the gap between the freezing pipe (3) and the shield shell (23); the grouting part is installed on the freezing pipe (3) and the sealing part to grout the circumferential strata of the freezing hole along the freezing pipe (3) or the gap between the freezing pipe (3) and the shield shell (23).

3. The bidirectional grouting process using freezing pipes according to claim 2, characterized in that, The sealing part includes a sealing box sleeve (8), a sealing box tube (9), a connecting ball valve (11), and an orifice tube (21) all fitted on the freezing pipe (3); one end of the orifice tube (21) is connected to the shield shell (23), and the other end is connected to the connecting ball valve (11); the other end of the connecting ball valve (11) is connected to one end of the sealing box tube (9); the sealing box sleeve (8) is used to seal the other end of the sealing box tube (9).

4. The bidirectional grouting process using a freezing pipe according to claim 3, characterized in that, The grouting section includes a grouting ball valve (1), a bypass ball valve (18), and a sealing component; the grouting ball valve (1) is connected to the far-end grouting connector (2) installed at the feed end of the freezing pipe (3); the bypass ball valve (18) is installed on the orifice pipe (21) and is connected to the near-end grout outlet (24) between the freezing pipe (3) and the shield shell (23); the sealing component is installed at the discharge port of the freezing pipe (3) and is used to open or block the discharge port of the freezing pipe (3).

5. The bidirectional grouting process using a freezing pipe according to claim 4, characterized in that, The sealing component includes a one-way valve plug (25) and a one-way valve (26); the one-way valve (26) is provided with a remote slurry outlet (27); the one-way valve plug (25) is used to seal the remote slurry outlet (27) and forms a threaded connection with the one-way valve (26).

6. The bidirectional grouting process using a freezing pipe according to claim 4, characterized in that, A first flange (4) is provided between the sealing box sleeve (8) and the freezing pipe (3).

7. The bidirectional grouting process using a freezing pipe according to claim 4, characterized in that, A second flange (6) is provided between the sealing box sleeve (8) and the sealing box tube (9) for connection, and tallow packing (10) is filled between the sealing box tube (9) and the freezing tube (3).

8. The bidirectional grouting process using a freezing pipe according to claim 7, characterized in that, A third flange (13) for connection and a retaining ring (15) for sealing are provided between the sealing box tube (9) and the connecting ball valve (11).

9. The bidirectional grouting process using a freezing pipe according to claim 8, characterized in that, A fourth flange (16) for connection is provided between the connecting ball valve (11) and the orifice pipe (21).

Images