A method for the construction of a deep freeze borehole pipe and mechanical seal

Abstract

The application discloses a kind of for deep freeze hole pipe, including hole pipe, freezing pipe and cement paste layer, the first end of the hole pipe is inserted into tunnel segment and is fixedly connected with tunnel segment, the first end of the freezing pipe passes through the hole pipe and is inserted into stratum, cement paste layer is injected between the hole pipe and the freezing pipe, the second end of the hole pipe is coaxially provided with reducing pipe on end, water stop steel ring and O type sealing ring are installed in the reducing pipe, the water stop steel ring and the O type sealing ring are all covered on freezing pipe, the water stop steel ring one side is consistent with the second end of hole pipe, and the cement paste layer is contacted with the water stop steel ring.The application, by setting up compression assembly and compressing O type sealing ring, play the role of sealing gap between hole pipe and freezing pipe, can effectively realize the mechanical sealing connection between deep freeze 304 stainless steel freezing pipe and low carbon steel hole device, reduce the welding workload on site.

Description

Technical Field

[0001] This invention relates to the field of freezing construction technology. Specifically, it is a method for deep freezing of orifice pipes and mechanical seals. Background Technology

[0002] Freezing is an important construction method for traversing complex geological formations and water-rich soft soil strata. It utilizes artificial refrigeration to freeze the water in the soil, forming a solid, sealed frozen soil ring (frozen wall) to resist soil and water pressure and isolate groundwater. Excavation and construction are then carried out under the protection of this frozen wall. During the freezing process, freezing pipes are drilled into the strata, and brine circulates inside the pipes to freeze the strata. Currently, freezing technology in my country is divided into two types: brine freezing and liquid nitrogen freezing. Brine freezing uses a calcium chloride solution at -28℃ to -30℃ as a coolant to deliver cooling energy into the soil. Excavation and construction can begin after 45-60 days of active freezing, resulting in a long construction period. Liquid nitrogen freezing is mostly used for emergency rescue and projects with tight schedules. Liquid nitrogen directly vaporizes within the soil circulation system, absorbing heat from the soil. Liquid nitrogen has a temperature of -196℃, and the temperature after vaporization and discharge is approximately -80℃. This method results in significant waste of cooling energy, a risk of suffocation, and costs 3-5 times higher than brine freezing.

[0003] Currently, both the freezing pipes and orifice pipes for calcium chloride solutions operating at -28℃ to -30℃ are made of low-carbon steel. Therefore, after drilling, the sealing is achieved by directly welding a ring to the borehole to prevent water and sand from the formation from seeping out through the gap between the orifice pipe and the freezing pipe. When using liquid nitrogen freezing, the working temperature is around -50℃. The existing low-carbon steel freezing pipes are not suitable for this temperature range and are prone to brittle fracture. Freezing pipes made of 304 stainless steel or higher grade stainless steel are required to meet the requirements of deep freezing. However, welding 304 stainless steel freezing pipes to low-carbon steel orifice pipes is difficult, and the original welding sealing method is no longer applicable. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a construction method for a deep freezing orifice pipe and a mechanical seal that can seal stainless steel freezing pipes and low carbon steel orifice pipes.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a deep cryogenic grouting orifice pipe, comprising an orifice pipe, a freezing pipe, and a cement slurry layer, wherein the first end of the orifice pipe is inserted into a tunnel segment and fixedly connected to the tunnel segment, the first end of the freezing pipe passes through the orifice pipe and is inserted into the formation, a cement slurry layer is injected between the orifice pipe and the freezing pipe, a reducing pipe is coaxially provided on the second end of the orifice pipe, a water-stop steel ring and an O-ring are installed inside the reducing pipe, both the water-stop steel ring and the O-ring are fitted on the freezing pipe, one side of the water-stop steel ring is in contact with the second end of the orifice pipe, and the cement slurry layer is in contact with the water-stop steel ring, the O-ring is in contact with the other side of the water-stop steel ring, a clamping assembly is installed on the second end of the reducing pipe, the end of the clamping assembly is inserted into the reducing pipe and compresses the O-ring to deform, so that the O-ring seals between the freezing pipe and the reducing pipe. By setting up a clamping assembly to press the O-ring seal, the gap between the orifice pipe and the freezing pipe is sealed, effectively achieving a mechanical seal connection between the cryogenically frozen 304 stainless steel freezing pipe and the low-carbon steel orifice device. This reduces on-site welding workload and minimizes the harm of welding fumes to workers. The water-stop steel ring, which fits snugly against the end of the orifice pipe, prevents pressure from being transmitted to the cement grout layer when the clamping assembly applies pressure to the O-ring seal, thus avoiding compression damage to the cement grout layer. Simultaneously, the water-stop steel ring prevents the O-ring seal from contacting both the cement grout layer and the reducing pipe simultaneously, reducing O-ring seal wear and maintaining a stable and effective seal.

[0006] The aforementioned type of orifice pipe for deep freezing has an inner diameter greater than that of the orifice pipe, and a water-stop steel ring is fitted with a clearance within the variable diameter pipe, wherein the inner diameter of the water-stop steel ring is greater than that of the freezing pipe.

[0007] In the aforementioned deep-freezing orifice pipe, the inner diameter of the water-stop steel ring is 2 cm larger than the outer diameter of the freezing pipe. Two O-rings are used, and their inner and outer diameters are the same as those of the water-stop steel ring. Designing the inner diameter of the water-stop steel ring to be larger than the outer diameter of the freezing pipe avoids mutual compression and friction between the freezing pipe and the water-stop steel ring during thermal expansion and contraction due to the different materials, thus preventing deformation or damage to the freezing pipe.

[0008] In the aforementioned deep-freezing orifice tube, the reducing tube is made of the same material as the orifice tube, and the clamping assembly is made of the same material as the freezing tube. By using clamping assemblies and freezing tubes of the same material, deformation of the freezing tube due to compression can be avoided.

[0009] The aforementioned orifice tube for deep cryogenic freezing is made of low-carbon steel for both the reducing tube and the orifice tube, and 304 stainless steel for both the clamping assembly and the freezing tube. The fact that both the clamping assembly and the freezing tube are made of 304 stainless steel ensures they have the same coefficient of thermal expansion, making them coaxial and preventing uneven clamping force caused by bias. This guarantees uniform pressure on the O-ring seal and ensures a good sealing effect.

[0010] The above-mentioned orifice pipe for deep freezing includes a clamping assembly comprising a sealing clamping tube, a sealing flange, and tie bolts. An orifice pipe flange is coaxially fixedly connected to the second end of the reducing pipe. The sealing clamping tube is fitted onto the freezing pipe. The first end of the sealing clamping tube is inserted into the reducing pipe and pressed against the O-ring. The sealing flange is coaxially fixed to the second end of the sealing clamping tube. Tensioning holes are respectively formed along the circumferential direction on the orifice pipe flange and the sealing flange. One end of the tie bolt passes through the tensioning hole on the orifice pipe flange, and the other end of the tie bolt passes through the tensioning hole on the sealing flange. Nuts are threaded onto both ends of the tie bolt.

[0011] In the above-mentioned deep cryogenic orifice tube, the inner diameter of the sealing pressure tube is clearance-fitted with the outer diameter of the freezing tube, ensuring that the sealing pressure tube can be freely adjusted relative to the freezing tube to adjust the clamping force on the O-ring seal.

[0012] The above-mentioned perforated pipe for deep freezing has a perforated steel plate welded onto it, and the perforated steel plate is fixedly connected to the tunnel segment by expansion bolts; a ball valve is installed on the side wall of the perforated pipe through a pipeline.

[0013] A method for constructing a mechanical seal for a cryogenic orifice pipe, characterized by comprising the following steps:

[0014] Step A: Drill holes in the tunnel segments, insert the first end of the hole pipe into the tunnel segments and fix it to the tunnel segments;

[0015] Step B: Pass the first end of the freezing pipe through the orifice pipe and insert it into the formation, and inject a layer of cement grout between the orifice pipe and the freezing pipe;

[0016] Step C: A reducing pipe is coaxially installed on the second end of the orifice pipe. A water-stop steel ring and an O-ring are installed inside the reducing pipe, so that both the water-stop steel ring and the O-ring are fitted onto the freezing pipe. One side of the water-stop steel ring is in contact with the second end of the orifice pipe, the cement slurry layer is in contact with the water-stop steel ring, and the O-ring is in contact with the other side of the water-stop steel ring.

[0017] Step D: A clamping assembly is installed on the second end of the reducer. The clamping assembly is operated so that its end is inserted into the reducer and the O-ring is deformed, so that the O-ring is sealed between the freezer and the reducer.

[0018] The technical solution of the present invention achieves the following beneficial technical effects:

[0019] 1. This invention, by setting a clamping component to clamp the O-ring seal, effectively seals the gap between the orifice pipe and the freezing pipe, thereby achieving a mechanical seal connection between the cryogenically frozen 304 stainless steel freezing pipe and the low-carbon steel orifice device. This reduces on-site welding workload and minimizes the harm of welding fumes to workers. The water-stop steel ring, which fits snugly against the end of the orifice pipe, prevents the clamping component from transmitting pressure to the cement slurry layer when applying pressure to the O-ring seal, thus avoiding compression damage to the cement slurry layer. Simultaneously, the water-stop steel ring prevents the O-ring seal from contacting both the cement slurry layer and the reducing pipe simultaneously, reducing wear on the O-ring seal and maintaining a stable and effective seal.

[0020] 2. This invention designs the inner diameter of the water-stop steel ring to be larger than the outer diameter of the freezing pipe. Since different materials have different coefficients of thermal expansion and contraction, this design prevents the freezing pipe and the water-stop steel ring from contacting, squeezing, and rubbing against each other during thermal expansion and contraction, thus preventing deformation or damage to the freezing pipe. By using a clamping assembly and the freezing pipe made of the same material, deformation of the freezing pipe can be avoided. Both the clamping assembly and the freezing pipe are made of 304 stainless steel, and both have the same coefficient of thermal expansion and contraction. During construction, this ensures the coaxiality of the clamping assembly and the freezing pipe, preventing uneven pressure applied to the O-ring and ensuring uniform pressure on the O-ring for a good sealing effect. Attached Figure Description

[0021] Figure 1 A cross-sectional structural diagram of the present invention;

[0022] Figure 2 A schematic diagram of the sealing flange of this invention.

[0023] The reference numerals in the figure are as follows: 1-orifice pipe; 2-reducing pipe; 3-freezing pipe; 4-orifice pipe flange; 5-sealing pressure pipe; 6-sealing flange; 7-tie bolt; 8-waterstop steel ring; 9-O-ring seal; 10-cement grout layer; 11-ball valve; 12-tunnel segment; 13-orifice steel plate; 14-stratum. Detailed Implementation

[0024] Example 1

[0025] One embodiment of this example uses a cryogenic orifice tube. Please refer to [link to relevant documentation]. Figure 1-2The system includes an orifice pipe 1, a freezing pipe 3, and a cement grout layer 10. The first end of the orifice pipe 1 is inserted into a tunnel segment 12 and fixedly connected to it. The first end of the freezing pipe 3 passes through the orifice pipe 1 and is inserted into the stratum 14. A cement grout layer 10 is injected between the orifice pipe 1 and the freezing pipe 3. A reducing pipe 2 is coaxially mounted on the second end of the orifice pipe 1. A water-stop steel ring 8 and an O-ring seal 9 are installed inside the reducing pipe 2. Both the water-stop steel ring 8 and the O-ring seal 9 are fitted onto the freezing pipe 3. One side of the water-stop steel ring 8 is in contact with the second end of the orifice pipe 1, and the cement grout layer 10 is in contact with the water-stop steel ring 8. The O-ring seal 9 is attached to the other side of the water-stop steel ring 8. A clamping assembly is installed on the second end of the reducing pipe 2, which is connected to the end of the orifice pipe 1. The sealing steel ring 8 prevents the pressure from being transmitted to the cement grout layer 10 when the clamping assembly applies pressure to the O-ring seal 9, thus avoiding compression damage to the cement grout layer 10. Simultaneously, the sealing steel ring 8 prevents the O-ring seal 9 from contacting both the cement grout layer 10 and the reducing pipe 2 simultaneously, reducing wear on the O-ring seal 9 and maintaining a stable and good sealing effect. The end of the clamping assembly is inserted into the reducing pipe 2 and compresses the O-ring seal 9, causing it to seal between the freezing pipe 3 and the reducing pipe 2. By clamping the O-ring seal 9 with the clamping assembly, the gap between the orifice pipe 1 and the freezing pipe 3 is sealed, effectively achieving a mechanical seal connection between the cryogenically frozen 304 stainless steel freezing pipe and the low-carbon steel orifice device, reducing on-site welding workload and minimizing the harm of welding fumes to workers.

[0026] In actual construction, the reducing pipe 2 can be enlarged by 10 cm at the second end of the orifice pipe 1, increasing the diameter by 4 cm based on the original inner diameter of the reducing pipe 2. In other embodiments, the reducing pipe 2 can also be made by coaxially welding a low carbon steel pipe of the required size to the end of the orifice pipe 1.

[0027] The inner diameter of the reducing pipe 2 is larger than the inner diameter of the orifice pipe 1. The water-stop steel ring 8 is fitted with a clearance inside the reducing pipe 2. The inner diameter of the water-stop steel ring 8 is larger than the outer diameter of the freezing pipe 3. The inner diameter of the water-stop steel ring 8 is 2 cm larger than the outer diameter of the freezing pipe 3. There are two O-rings 9, and the inner and outer diameters of the O-rings 9 are the same as the inner and outer diameters of the water-stop steel ring 8. By designing the inner diameter of the water-stop steel ring 8 to be larger than the outer diameter of the freezing pipe 3, the different coefficients of thermal expansion and contraction due to different materials prevent the freezing pipe 3 and the water-stop steel ring 8 from squeezing and rubbing against each other when they expand and contract, thus preventing the freezing pipe 3 from deforming or breaking.

[0028] The reducing pipe 2 is made of the same material as the orifice pipe 1, both being low-carbon steel. The clamping assembly is made of the same material as the freezing pipe 3, both being 304 stainless steel. By using clamping assemblies and freezing pipe 3 of the same material, deformation of the freezing pipe 3 can be prevented. Since both materials are 304 stainless steel, their coefficients of thermal expansion and contraction are the same. During construction, ensuring the coaxiality of the clamping assembly and freezing pipe 3 prevents uneven clamping force caused by bias pressure, thus ensuring uniform pressure on the O-ring seal 9 and guaranteeing a good sealing effect.

[0029] The clamping assembly includes a sealing pressure tube 5, a sealing flange 6, and a tie bolt 7. An orifice flange 4 is coaxially fixedly connected to the second end of the reducing pipe 2. The sealing pressure tube 5 is sleeved on the freezing pipe 3. The first end of the sealing pressure tube 5 is inserted into the reducing pipe 2 and pressed against the O-ring 9. The sealing flange 6 is coaxially fixed to the second end of the sealing pressure tube 5. Tensioning holes are respectively opened on the orifice flange 4 and the sealing flange 6 along the circumferential direction. One end of the tie bolt 7 passes through the tensioning hole on the orifice flange 4, and the other end of the tie bolt 7 passes through the tensioning hole on the sealing flange 6. Nuts are threaded to both ends of the tie bolt 7. The inner diameter of the sealing pressure tube 5 is clearance-fitted with the outer diameter of the freezing pipe 3.

[0030] A perforated steel plate 13 is welded onto the perforated pipe 1, and the perforated steel plate 13 is fixedly connected to the tunnel segment 12 by expansion bolts; a ball valve 11 is installed on the side wall of the perforated pipe 1 through a pipeline.

[0031] Workflow: The orifice pipe 1 is made of existing low-carbon steel, which is low in cost and easy to process and cut. The end of the orifice pipe 1 is enlarged to form the reducer pipe 2. After the freezing pipe 3 is drilled, grouting is performed at the orifice. After grouting, cement slurry is used to fill the gap between the orifice pipe 1 and the freezing pipe 3. After the cement solidifies, the original large ball valve and clamping device are removed. A water-stop steel ring 8 with a radius 2cm larger than the radius of the freezing pipe 3 is placed in the gap between the reducer pipe 2 and the freezing pipe. The water-stop steel ring 8 is in contact with the cement slurry layer 10. Two rubber O-rings 9 are installed after the water-stop steel ring 8. The diameter of the O-rings 9 is the same as that of the water-stop steel ring 8. The sealing pressure pipe 5 is inserted into the gap between the orifice pipe 1 and the freezing pipe 3. The orifice pipe flange 4 and the sealing flange 6 are tightened by tightening the nuts. The O-rings 9 are pressed by the sealing pressure pipe 5 to prevent water and sand from flowing into the gap between the orifice pipe 1 and the freezing pipe 3.

[0032] Example 2

[0033] This embodiment provides a method for constructing a mechanical seal for a cryogenic orifice pipe, comprising the following steps:

[0034] Step A: Drill a hole in the tunnel segment 12, insert the first end of the hole pipe 1 into the tunnel segment 12 and fix it to the tunnel segment 12.

[0035] Step B: Pass the first end of the freezing pipe 3 through the orifice pipe 1 and insert it into the formation 14, and inject a cement slurry layer 10 between the orifice pipe 1 and the freezing pipe 3;

[0036] Step C: A reducing pipe 2 is coaxially installed on the second end of the orifice pipe 1. A water-stop steel ring 8 and an O-ring seal 9 are installed inside the reducing pipe 2, so that the water-stop steel ring 8 and the O-ring seal 9 are both fitted on the freezing pipe 3. One side of the water-stop steel ring 8 is in contact with the second end of the orifice pipe 1, the cement grout layer 10 is in contact with the water-stop steel ring 8, and the O-ring seal 9 is in contact with the other side of the water-stop steel ring 8.

[0037] Step D: A clamping assembly is installed on the second end of the reducing pipe 2. The clamping assembly is operated so that the end of the clamping assembly is inserted into the reducing pipe 2 and the O-ring 9 is deformed, so that the O-ring 9 seals between the freezing pipe 3 and the reducing pipe 2.

[0038] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A deep-freezing orifice pipe, comprising an orifice pipe (1), a freezing pipe (3), and a cement grout layer (10), wherein the first end of the orifice pipe (1) is inserted into a tunnel segment (12) and fixedly connected to the tunnel segment (12), the first end of the freezing pipe (3) passes through the orifice pipe (1) and is inserted into the formation (14), and a cement grout layer (10) is injected between the orifice pipe (1) and the freezing pipe (3), characterized in that, A reducing pipe (2) is coaxially arranged on the second end of the orifice pipe (1). A water-stop steel ring (8) and an O-ring seal (9) are installed inside the reducing pipe (2). The water-stop steel ring (8) and the O-ring seal (9) are both fitted on the freezing pipe (3). One side of the water-stop steel ring (8) is in contact with the second end of the orifice pipe (1), and the cement slurry layer (10) is in contact with the water-stop steel ring (8). The O-ring seal (9) is in contact with the other side of the water-stop steel ring (8). A clamping assembly is installed on the second end of the reducing pipe (2). The end of the clamping assembly is inserted into the reducing pipe (2) and presses the O-ring seal (9) to deform, so that the O-ring seal (9) seals between the freezing pipe (3) and the reducing pipe (2). The inner diameter of the water-stop steel ring (8) is larger than the outer diameter of the freezing pipe (3); The reducing pipe (2) and the orifice pipe (1) are both made of low-carbon steel, and the clamping assembly and the freezing pipe (3) are both made of 304 stainless steel.

2. The orifice tube for deep cryogenic freezing according to claim 1, characterized in that, The inner diameter of the reducing pipe (2) is larger than the inner diameter of the orifice pipe (1), and the water-stop steel ring (8) is fitted with a clearance inside the reducing pipe (2).

3. The orifice tube for deep cryogenic freezing according to claim 2, characterized in that, The inner diameter of the water-stop steel ring (8) is 2 cm larger than the outer diameter of the freezing pipe (3). There are two O-rings (9), and the inner and outer diameters of the O-rings (9) are the same as the inner and outer diameters of the water-stop steel ring (8).

4. A deep-freezing orifice tube according to claim 1, characterized in that, The clamping assembly includes a sealing clamping tube (5), a sealing flange (6), and a tie bolt (7). A bore flange (4) is coaxially fixed to the second end of the reducing pipe (2). The sealing clamping tube (5) is sleeved on the freezing pipe (3). The first end of the sealing clamping tube (5) is inserted into the reducing pipe (2) and pressed against the O-ring seal (9). The sealing flange (6) is coaxially fixed to the second end of the sealing clamping tube (5). Tensioning holes are respectively opened on the bore flange (4) and the sealing flange (6) along the circumferential direction. One end of the tie bolt (7) passes through the tensioning hole on the bore flange (4), and the other end of the tie bolt (7) passes through the tensioning hole on the sealing flange (6). Nuts are threaded to both ends of the tie bolt (7).

5. A deep-freezing orifice tube according to claim 4, characterized in that, The inner diameter of the sealing pressure tube (5) is clearance-fitted with the outer diameter of the freezing tube (3).

6. A deep-freezing orifice tube according to claim 1, characterized in that, A perforated steel plate (13) is welded onto the perforated pipe (1), and the perforated steel plate (13) is fixedly connected to the tunnel segment (12) by expansion bolts; a ball valve (11) is installed on the side wall of the perforated pipe (1) through a pipeline.

7. A method for constructing a mechanical seal for a cryogenically frozen orifice pipe as described in any one of claims 1-6, characterized in that, Includes the following steps: Step A: Make a hole in the tunnel segment (12), insert the first end of the hole pipe (1) into the tunnel segment (12) and fix it to the tunnel segment (12); Step B: Pass the first end of the freezing pipe (3) through the orifice pipe (1) and insert it into the formation (14), and inject a cement slurry layer (10) between the orifice pipe (1) and the freezing pipe (3). Step C: A reducing pipe (2) is coaxially installed on the second end of the orifice pipe (1). A water-stop steel ring (8) and an O-ring seal (9) are installed inside the reducing pipe (2) so that the water-stop steel ring (8) and the O-ring seal (9) are both fitted on the freezing pipe (3). One side of the water-stop steel ring (8) is in contact with the second end of the orifice pipe (1), the cement grout layer (10) is in contact with the water-stop steel ring (8), and the O-ring seal (9) is in contact with the other side of the water-stop steel ring (8). Step D: A clamping assembly is installed on the second end of the reducing pipe (2). The clamping assembly is operated so that the end of the clamping assembly is inserted into the reducing pipe (2) and the O-ring (9) is deformed, so that the O-ring (9) seals between the freezing pipe (3) and the reducing pipe (2).

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