Method for controlling frost heaving through soil body segmented and time-sharing freezing for connection channel construction

Abstract

The invention discloses a method for controlling frost heaving by freezing a soil body in a segmented and time-sharing manner for connecting channel construction, which is applied to the field of tunnel construction. An area to be frozen is divided into an upper area, a middle area and a lower area, and the construction sequence of freezing the upper area and the lower area first and then freezing the middle area is adopted; according to the invention, frost heaving deformation of frozen soil in the upper area and the lower area can be released towards unfrozen soil in the middle area, so that the deformation quantity of the frozen soil in the vertical direction during freezing is reduced, and the probability that a foundation and a building above the frozen area are damaged by frost heaving extrusion of the frozen soil is reduced; the vertical frost heaving deformation of the frozen soil in the middle area is restrained by the frozen walls at the upper end and the lower end, the frozen soil in the middle area is mainly subjected to frost heaving deformation in the horizontal direction, the influence of the frost heaving deformation of the frozen soil on an upper foundation and a building is reduced, segmented and time-sharing quick freezing is achieved, and the construction safety and the construction efficiency are further improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction, and in particular to a method for controlling frost heave by segmenting and timing the freezing of soil for the construction of connecting passages. Background Technology

[0002] In the development of underground space, such as urban rail transit and tunnel engineering, connecting passages serve as structures linking two main tunnels, undertaking critical functions such as emergency evacuation, equipment passage, and ventilation. However, when connecting passages traverse complex geological conditions (such as soft clay, sand, or composite strata with high water content and high permeability), traditional construction methods (such as open-cut excavation and shield tunneling) face significant safety risks, including ground instability, water and sand inrush, and excessive surface settlement, which may even lead to damage to surrounding buildings or the rupture of underground pipelines.

[0003] To address the aforementioned challenges, the freezing method, a ground reinforcement technology that uses artificial refrigeration to create a frozen soil curtain, has gradually become the preferred solution for the construction of connecting passages in high-risk areas. Its core principle involves using a low-temperature refrigerant (such as calcium chloride brine or liquid nitrogen) circulated through freezing pipes to freeze the moisture in the ground into high-strength, low-permeability frozen soil, thus forming a closed frozen soil curtain around the excavation area. This curtain can withstand ground water and soil pressure (e.g., the compressive strength of frozen sand at -10℃ can reach over 8MPa) and effectively block groundwater (the permeability coefficient can be reduced to 10⁻). 8 (on the order of cm / s), providing a dry and stable construction environment for the excavation and lining of the connecting passage.

[0004] However, in existing freezing construction methods, the operation mode of freezing the entire area to be frozen is usually adopted. During the overall freezing process, the soil will undergo significant frost heave, resulting in large frost heave deformation. Such deformation can easily have a destructive impact on surrounding buildings, roads, and adjacent underground structures and pipelines, seriously threatening construction safety. Summary of the Invention

[0005] The core of this invention lies in dividing the area to be frozen into three regions—upper, middle, and lower—and adopting an operation method of freezing the upper and lower regions first, followed by freezing the middle region. This solves the problem of excessive soil deformation caused by the overall freezing method in the prior art, which easily damages the surrounding soil layers and buildings. At the same time, the frost heave pressure is actively controlled by a pressure relief pipe that can adjust the frost heave pressure.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A method for controlling frost heave by segmenting and timing the freezing of soil for the construction of a connecting passage includes the following steps: Step 1, Design of the freezing area: Based on the design data of the connecting channel, the area to be frozen is divided into vertically distributed upper, middle and lower areas. Then, based on the geological conditions and actual working conditions, the number and location of the freezing pipes, temperature measuring pipes and pressure relief pipes are determined. Step 2: Determine the drilling location; prepare the construction equipment and materials, and build a construction platform inside the tunnel. Based on the area division determined in Step 1 and the arrangement of freezing pipes, temperature measuring pipes and pressure relief pipes, mark the drilling location on the construction working surface inside the tunnel. Step 3, Drilling operation: Based on the drilling marks determined in Step 2, drilling operation is carried out on the construction surface inside the tunnel; Step 4, Equipment Installation: After drilling is completed, install the corresponding freezing pipe, temperature measuring pipe and pressure relief pipe into the corresponding drill hole, and then connect the freezing pipe to the external refrigeration circulation machine. Step 5, freezing construction: First, low-temperature brine is circulated in the freezing pipes located in the upper and lower regions to freeze and reinforce the soil in the upper and lower regions. The thickness and development range of the frozen wall are calculated using the temperature monitored by the temperature measuring tube. When the thickness of the frozen wall in the upper and lower regions reaches the set first threshold, freezing brine is injected into the freezing pipe located in the middle region to freeze the middle region. Step six: When the thickness of the frozen wall in the central area reaches the set second threshold, the segmented and time-based freezing operation is completed, and then the frozen state is maintained.

[0008] As a further embodiment of the present invention, the center line of the central region coincides with the center line of the region to be frozen. On the central horizontal plane of the central region, multiple temperature measuring tubes are arranged linearly and equidistantly along the direction of the connecting channel. One temperature measuring tube is arranged in the upper region and one in the lower region. There are two pressure relief tubes, which are arranged in the central region.

[0009] As a further aspect of the present invention, the distribution density of the freezing tubes in the upper and lower regions is greater than that in the middle region, and multiple vertically equidistantly distributed freezing tubes are provided in the vertical plane of the center of the connecting channel to be built.

[0010] As a further aspect of the present invention, in the freezing construction of step five, the brine circulation flow rate in the middle region is greater than that in the upper and lower regions, and the circulating brine temperature in the middle region is lower than that in the upper and lower regions.

[0011] As a further embodiment of the present invention, an adjustable frost heave pressure relief pipe is adopted. The pressure relief pipe includes an outer pipe inserted into the area to be frozen. The end of the outer pipe located in the tunnel is fixedly connected to a drain pipe. Multiple filter screens are fixedly connected to the outer wall of the outer pipe. The filter screens have filter holes that communicate with the inner cavity of the outer pipe. An adjusting roller is rotatably connected to the inner wall of the outer pipe. The adjusting roller has a material discharge groove that corresponds to each filter screen. A conical cavity is opened at the central axis of the adjusting roller. The inner end of the material discharge groove communicates with the conical cavity. A connecting rod is fixedly connected to the end of the adjusting roller near the drain pipe. The connecting rod is located above the connection between the drain pipe and the outer pipe. A rotating disk is fixedly connected to the connecting rod. The rotating disk is rotatably connected to the inner wall of the outer pipe. The output shaft of a motor is fixedly connected to the outer end of the rotating disk. The housing of the motor is fixedly connected to the side wall of the outer pipe.

[0012] As a further embodiment of the present invention, the filter screen is an arc-shaped screen plate, the outer wall of the adjusting roller is slidably connected to the inner wall of the filter screen, the outer tube is provided with mounting holes for fixing the filter screen, the material chute is a through hole with a fan-shaped cross-section, the conical cavity is a conical hole that is narrow on the left and wide on the right and open at the right end, and the end near the drain pipe is wide.

[0013] As a further embodiment of the present invention, an electrically controlled valve, a pressure sensor, and a flow sensor are fixedly connected to the drain pipe, and the electrically controlled valve, pressure sensor, flow sensor, and motor are all electrically connected to the computer in the monitoring room.

[0014] Compared with the prior art, the advantages of this invention are: (1) By freezing the upper and lower regions first, the frozen soil in the upper and lower regions can release the frost heave deformation towards the unfrozen soil in the middle region, making the middle region a frost heave buffer zone when the upper and lower regions freeze. This provides vertical release space for the frost heave of the frozen soil in the upper and lower regions, reduces the vertical deformation of the frozen soil when freezing, and reduces the probability of the foundation and buildings above the frozen area being damaged by frost heave. In addition, after the upper and lower regions are frozen, hard frozen walls are formed at the upper and lower ends of the middle region. At this time, the freezing operation of the middle region is started. The vertical frost heave deformation of the frozen soil in the middle region is constrained by the frozen walls at the upper and lower ends. The frozen soil in the middle region mainly undergoes horizontal freezing deformation, reducing the impact of the frost heave deformation of the frozen soil on the upper foundation and buildings. By freezing in segments and at different times, the safety and efficiency of construction are further improved.

[0015] (2) The present invention uses an outer pipe with a distributed filter screen, so that the mud and water in the frost heave area enters the interior of the pressure relief pipe from various positions and is collected and discharged, thereby reducing the impact of the mud and water flow in the frost heave area on the stability of the soil structure. Furthermore, the rotatable adjusting roller is used to adjust the mud and water discharge speed, thereby realizing the active adjustment of the frost heave pressure. In addition, the combination design of the material drop chute and the conical cavity reduces the risk of clogging of the filter screen and the adjusting roller, thereby reducing the probability of clogging of the pressure relief pipe. Attached Figure Description

[0016] Figure 1 This is a flowchart of the freezing construction process of the present invention; Figure 2 This is a schematic diagram illustrating the division of the upper, middle, and lower regions in this invention; Figure 3 This is a schematic diagram showing the distribution of the freezing tube, temperature measuring tube, and pressure relief tube in this invention; Figure 4 This is a three-dimensional structural diagram of the pressure relief pipe in this invention; Figure 5 This is a schematic diagram of the axial cross-sectional structure of the pressure relief pipe in this invention; Figure 6 This is a schematic diagram of the exploded assembly structure of the pressure relief pipe in this invention; Figure 7 This is a schematic diagram of the axial cross-sectional structure of the adjusting roller in this invention; Figure 8 This is a schematic diagram illustrating the state of the adjusting roller rotating to adjust the mud and water inlet volume in this invention.

[0017] The following are the labels in the diagram: 1. Freezing pipe; 2. Temperature measuring pipe; 3. Pressure relief pipe; 4. Outer pipe; 401. Mounting hole; 5. Drain pipe; 6. Electrically controlled valve; 7. Pressure sensor; 8. Flow sensor; 9. Filter screen; 901. Filter hole; 10. Adjusting roller; 1001. Material chute; 1002. Conical cavity; 11. Connecting rod; 12. Rotating disk; 13. Motor. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Please see Figure 1-3 In one embodiment of the present invention, a method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage includes the following steps: Step 1, Design of the freezing area: Based on the design data of the connecting channel, the area to be frozen is divided into vertically distributed upper, middle and lower areas. Then, based on the geological conditions and actual working conditions, the number and location of freezing pipe 1, temperature measuring pipe 2 and pressure relief pipe 3 are determined. For details, please refer to Figure 2 and Figure 3 The center line of the middle area coincides with the center line of the area to be frozen. On the central horizontal plane of the middle area, multiple temperature measuring tubes 2 are arranged linearly and equidistantly along the direction of the connecting channel. One temperature measuring tube 2 is arranged in the upper area and one in the lower area. There are two pressure relief tubes 3, which are arranged in the middle area. In addition, the distribution density of freezing pipe 1 in the upper and lower regions is greater than its distribution density in the middle region (the specific distribution density is affected by geological conditions and construction design requirements, and those skilled in the art can design based on the actual situation). Multiple vertically equidistantly distributed freezing pipes 1 are provided in the vertical plane of the center of the connecting channel to be built. Some of the multiple vertically equidistantly distributed freezing pipes 1 are located in the upper region, some in the lower region, and some in the middle region, which improves the overall freezing effect. It should be noted that the upper area is mainly distributed in the upper part of the connecting channel to be built, the lower area is mainly distributed in the lower part of the connecting channel to be built, and the middle area is mainly distributed in the middle part of the connecting channel to be built. Step 2: Determine the drilling location; prepare the construction equipment and materials, and build a construction platform inside the tunnel. Based on the area division determined in Step 1 and the arrangement of freezing pipe 1, temperature measuring pipe 2 and pressure relief pipe 3, mark the drilling location on the construction working surface inside the tunnel. Step 3, Drilling operation: Based on the drilling marks determined in Step 2, drilling operation is carried out on the construction surface inside the tunnel; Step 4, Equipment Installation: After drilling is completed, install the corresponding freezing pipe 1, temperature measuring pipe 2 and pressure relief pipe 3 into the corresponding drilled holes, and then connect the freezing pipe 1 to the external refrigeration circulation machine. Step 5, freezing construction: First, low-temperature brine is circulated in the freezing pipe 1 located in the upper and lower regions to freeze and reinforce the soil in the upper and lower regions. The thickness of the frozen wall is calculated using the temperature monitored by the temperature measuring pipe 2 (this is existing technology, and is generally calculated using the heat conduction theory formula, which will not be elaborated here). When the thickness of the frozen wall in the upper and lower regions reaches the set first threshold, freezing brine is injected into the freezing pipe 1 located in the middle region to freeze the middle region. Specifically, by freezing the upper and lower regions first, the frost heave deformation of the frozen soil in the upper and lower regions can be released towards the unfrozen soil in the middle region. This makes the middle region a frost heave buffer zone when the upper and lower regions freeze, providing vertical release space for the frost heave of the frozen soil in the upper and lower regions. This reduces the vertical deformation of the frozen soil during freezing and lowers the probability of the foundation and buildings above the frozen area being damaged by frost heave. In addition, after the upper and lower regions are frozen, hard frozen walls are formed at the upper and lower ends of the middle region. At this time, the freezing operation in the middle region is started. The vertical frost heave deformation of the frozen soil in the middle region is constrained by the frozen walls at the upper and lower ends. The frozen soil in the middle region mainly undergoes horizontal freezing deformation, further reducing the impact of frozen soil frost heave deformation on the upper foundation and buildings. By freezing in segments and at different times, the safety and efficiency of construction are improved. It should be noted that, since the vertical frost heave deformation of the frozen soil in the central region is constrained by the freezing walls at both the upper and lower ends, the freezing speed in the central region can be accelerated. Specific measures may include: 1. Ensuring that the brine circulation flow rate in the central region is greater than that in the upper and lower regions; 2. Ensuring that the circulating brine temperature in the central region is lower than that in the upper and lower regions; 3. Increasing the number of freezing pipes in the central region; thereby improving the overall freezing construction efficiency. Step six: When the thickness of the frozen wall in the central area reaches the set second threshold, the segmented and time-based freezing operation is completed, and then the frozen state is maintained.

[0022] It should be noted that the first and second thresholds need to be set based on actual geological conditions and construction requirements. For example, for construction areas with stable geological structures and low water content, the values ​​of the first and second thresholds are smaller, while for construction areas with loose geological structures and high water content, the values ​​of the first and second thresholds are larger.

[0023] In another embodiment of the invention, please refer to Figures 3-8An adjustable frost heave pressure relief pipe 3 is adopted. The pressure relief pipe 3 includes an outer pipe 4 inserted into the area to be frozen. The end of the outer pipe 4 located in the tunnel is fixedly connected to a drain pipe 5. Multiple filter screens 9 are fixedly connected to the outer wall of the outer pipe 4. The filter screens 9 have filter holes 901 that communicate with the inner cavity of the outer pipe 4. An adjusting roller 10 is rotatably connected to the inner wall of the outer pipe 4. The adjusting roller 10 has a material drop groove 1001 that corresponds to the filter screens 9. A conical cavity 1002 is opened at the central axis of the adjusting roller 10. The inner end of the material drop groove 1001 communicates with the conical cavity 1002. A connecting rod 11 is fixedly connected to the end of the adjusting roller 10 near the drain pipe 5. The connecting rod 11 is located above the connection between the drain pipe 5 and the outer pipe 4. A rotating disk 12 is fixedly connected to the connecting rod 11. The rotating disk 12 is rotatably connected to the inner wall of the outer pipe 4. The output shaft of a motor 13 is fixedly connected to the outer end of the rotating disk 12. The housing of the motor 13 is fixedly connected to the side wall of the outer pipe 4.

[0024] For details, please refer to Figure 5 and Figure 8 The motor 13 is started, which drives the adjusting roller 10 to rotate. The adjusting roller 10 drives the material chute 1001 on it to rotate, thereby adjusting the overlapping area of ​​the material chute 1001 and the filter screen 9. When the initial frost heave pressure in the middle region is the same, when the overlapping area increases, the amount of mud and water entering the material chute 1001 from the middle region through the filter screen 9 increases, and the freezing pressure in the middle region decreases. When the overlapping area decreases, the amount of mud and water entering the material chute 1001 from the middle region through the filter screen 9 decreases, and the frost heave pressure in the middle region increases. This achieves active adjustment of frost heave pressure, further controls the frost heave deformation of frozen soil, and improves the ability to actively control frost heave pressure.

[0025] Compared to traditional methods for addressing frost heave in frozen soil, this invention employs an outer pipe 4 with a distributed filter screen 9. This allows mud and water from the frost heave area to enter the pressure relief pipe 3 from various locations and then be collected and discharged. This reduces the impact of mud and water flow within the frost heave area on the stability of the soil structure. Furthermore, a rotatable adjusting roller 10 is used to regulate the mud and water discharge speed, enabling active regulation of the frost heave pressure. In addition, the combined design of the material discharge chute 1001 and the conical cavity 1002 reduces the risk of clogging of the filter screen 9 and the adjusting roller 10, thereby reducing the probability of clogging of the pressure relief pipe 3.

[0026] Please see Figures 5-7 The filter screen 9 is an arc-shaped screen plate. The outer wall of the adjusting roller 10 is slidably connected to the inner wall of the filter screen 9. The outer tube 4 is provided with an installation hole 401 for fixing the filter screen 9. The material chute 1001 is a through hole with a fan-shaped cross section. The conical cavity 1002 is a conical hole that is narrow on the left and wide on the right with an opening at the right end. The one near the drain pipe 5 is a wide opening.

[0027] Specifically, the design of the conical cavity 1002, which is higher on the left and lower on the right, can better collect mud and water, reducing the probability of clogging. At the same time, when the adjusting roller 10 rotates, it uses the open edge of the material chute 1001 to scrape and clean the inner wall of the filter screen 9, thereby improving the mud and water permeability of the filter screen 9.

[0028] Please see Figure 5 An electric control valve 6, a pressure sensor 7, and a flow sensor 8 are fixedly connected to the drain pipe 5. The electric control valve 6, pressure sensor 7, flow sensor 8, and motor 13 are all electrically connected to the computer in the monitoring room.

[0029] Specifically, the pressure and flow rate of the discharged mud and water are monitored by pressure sensor 7 and flow sensor 8, and the opening and closing of the drain pipe 5 is controlled by electric valve 6.

[0030] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A method for controlling frost heave by segmenting and timing the freezing of soil for the construction of a connecting passage, characterized in that, Includes the following steps: Step 1, design of the freezing area: Based on the design data of the connecting channel, the area to be frozen is divided into vertically distributed upper, middle and lower areas. Then, based on the geological conditions and actual working conditions, the number and location of the freezing pipe (1), temperature measuring pipe (2) and pressure relief pipe (3) are determined. Step 2: Determine the drilling location; prepare the construction equipment and materials, and build a construction platform inside the tunnel. Based on the area division determined in Step 1 and the arrangement of the freezing pipe (1), temperature measuring pipe (2) and pressure relief pipe (3), mark the drilling location on the construction working surface inside the tunnel. Step 3, Drilling operation: Based on the drilling marks determined in Step 2, drilling operation is carried out on the construction surface inside the tunnel; Step 4, Install equipment: After drilling is completed, install the corresponding freezing pipe (1), temperature measuring pipe (2) and pressure relief pipe (3) into the corresponding drill hole, and then connect the freezing pipe (1) to the external refrigeration circulation machine. Step 5, freezing construction: First, low temperature brine is circulated in the freezing pipe (1) located in the upper and lower regions to freeze and reinforce the soil in the upper and lower regions. The thickness and development range of the freezing wall are calculated by using the temperature monitoring tube (2). When the thickness of the freezing wall in the upper and lower regions reaches the set first threshold, freezing brine is injected into the freezing pipe (1) located in the middle region to freeze the middle region. Step six: When the thickness of the frozen wall in the central area reaches the set second threshold, the segmented and time-based freezing operation is completed, and then the frozen state is maintained.

2. The method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 1, is characterized in that... The center line of the middle area coincides with the center line of the area to be frozen. On the horizontal plane of the center of the middle area, multiple temperature measuring tubes (2) are arranged linearly and equidistantly along the direction of the connecting channel. One temperature measuring tube (2) is arranged in the upper area and one in the lower area. There are two pressure relief tubes (3), which are arranged in the middle area.

3. The method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 1, is characterized in that... The distribution density of the freezing tube (1) in the upper and lower regions is greater than its distribution density in the middle region. Multiple vertically equidistantly distributed freezing tubes (1) are provided in the vertical plane of the center of the connecting channel to be built.

4. The method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 1, is characterized in that... During the freezing process in step five, the brine circulation flow rate in the middle zone is made greater than that in the upper and lower zones, and the circulating brine temperature in the middle zone is lower than that in the upper and lower zones.

5. The method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 1, is characterized in that... An adjustable frost heave pressure relief pipe (3) is used. The pressure relief pipe (3) includes an outer pipe (4) inserted into the area to be frozen. The end of the outer pipe (4) located in the tunnel is fixedly connected to a drain pipe (5). Multiple filter screens (9) are fixedly connected to the outer wall of the outer pipe (4). The filter screens (9) are provided with filter holes (901) that communicate with the inner cavity of the outer pipe (4). An adjusting roller (10) is rotatably connected to the inner wall of the outer pipe (4). The adjusting roller (10) is provided with a material drop groove (1001) that corresponds one-to-one with the filter screen (9). The center axis of the adjusting roller (10) is positioned at... A conical cavity (1002) is provided, and the inner end of the material discharge chute (1001) is connected to the conical cavity (1002). The adjusting roller (10) is fixedly connected to a connecting rod (11) at one end near the drain pipe (5). The connecting rod (11) is located above the connection between the drain pipe (5) and the outer pipe (4). The connecting rod (11) is fixedly connected to a rotating disk (12). The rotating disk (12) is rotatably connected to the inner wall of the outer pipe (4). The outer end of the rotating disk (12) is fixedly connected to the output shaft of a motor (13). The housing of the motor (13) is fixedly connected to the side wall of the outer pipe (4).

6. The method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 5, is characterized in that... The filter screen (9) is an arc-shaped screen plate. The outer wall of the adjusting roller (10) is slidably connected to the inner wall of the filter screen (9). The outer tube (4) is provided with an installation hole (401) for fixing the filter screen (9). The material chute (1001) is a through hole with a fan-shaped cross section. The conical cavity (1002) is a conical hole that is narrow on the left and wide on the right with an opening at the right end. The end near the drain pipe (5) is a wide opening.

7. A method for controlling frost heave by segmented and timed freezing of soil for the construction of a connecting passage, as described in claim 6, is characterized in that... The drain pipe (5) is fixedly connected to an electric control valve (6), a pressure sensor (7) and a flow sensor (8). The electric control valve (6), pressure sensor (7), flow sensor (8) and motor (13) are all electrically connected to the computer in the monitoring room.

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