Pipe jacking machine jacking distance measuring device and method

Abstract

This invention discloses a device and method for measuring the jacking distance of a pipe jacking machine, comprising: a controller and a first measuring component; the first measuring component includes: a measuring wheel, the wheel surface of which is used to form frictional transmission contact with the outer surface of the pipe section moving during the jacking process; an encoder, coaxially connected to the measuring wheel; an encoder fixing plate, the first end of which is connected to the encoder; a mounting base; an adjusting rod, one end of which is fixedly connected to the mounting base, and the other end of which is fixedly connected to the second end of the encoder fixing plate; a pressure adjusting ring, disposed between the mounting base and the encoder fixing plate, and rotatably connected to the adjusting rod; a pre-tightening mechanism, one end of which is connected to the pressure adjusting ring, and the other end of which is connected to the encoder fixing plate, for applying a pre-tightening force toward the outer surface of the pipe section to the measuring wheel; the controller is connected to the encoder and calculates the jacking distance of the pipe jacking machine based on the output data of the encoder. This invention can realize real-time measurement of the jacking distance, obtain continuous and calibrable jacking distance data, effectively reduce errors, and improve measurement reliability.

Description

Technical Field

[0001] This invention relates to the field of underground trenchless construction monitoring and automated control, specifically to a device and method for measuring the jacking distance of a pipe jacking machine. Background Technology

[0002] Pipe jacking is a trenchless underground pipeline laying technology. It uses a pipe jacking machine to push pipe sections into the soil one by one to lay the pipeline underground. It is widely used in urban water supply and drainage, integrated pipe corridors, and gas pipeline construction.

[0003] In existing pipe jacking construction, there are two main methods for measuring the jacking distance: one is to manually record the number of jacked pipe sections and convert the jacking distance, which is cumbersome, inefficient, and prone to large errors; the other is to install a mileage encoder inside the pipe jacking machine and combine it with machine vision for guidance and distance measurement, which is complex and costly. Therefore, a convenient solution is needed to directly measure the movement of pipe sections at the tunnel entrance to obtain continuous and calibrable jacking distance data. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a device and method for measuring the jacking distance of a pipe jacking machine, which enables real-time measurement of the jacking distance, obtains continuous and calibrable jacking distance data, effectively reduces errors, and improves measurement reliability.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a pipe jacking machine jacking distance measuring device, comprising: a controller and a first measuring component;

[0007] The first measurement component includes:

[0008] The measuring wheel has its wheel surface used to form frictional transmission contact with the outer surface of the pipe section that moves during the jacking process;

[0009] An encoder, coaxially connected to the measuring wheel, is used to output a pulse signal corresponding to the rotation of the measuring wheel;

[0010] An encoder mounting plate, the first end of which is connected to the encoder;

[0011] Mounting bracket, used for installation near the starting working shaft opening of the pipe jacking machine;

[0012] One end of the adjusting rod is fixedly connected to the mounting base, and the other end is fixedly connected to the second end of the encoder fixing plate;

[0013] A pressure regulating ring is located between the mounting base and the encoder fixing plate, and is rotatably connected to the adjusting rod, and can rotate relative to the adjusting rod.

[0014] The pre-tightening mechanism is connected at one end to the pressure regulating ring and at the other end to the encoder fixing plate, and is used to apply a pre-tightening force toward the outer surface of the pipe section to the measuring wheel;

[0015] The controller is connected to the encoder and calculates the jacking distance of the pipe jacking machine based on the output data of the encoder.

[0016] In conjunction with the first aspect, optionally, the pipe jacking machine jacking distance measuring device further includes a second measuring component, the structure of which is the same as that of the first measuring component, and the encoder in the second measuring component is connected to the controller.

[0017] In conjunction with the first aspect, optionally, the controller calculates the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine based on the output data of the encoder in the first measuring component and the encoder in the second measuring component, respectively.

[0018] When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds a preset difference threshold, a slippage signal or an abnormal alarm signal will be output.

[0019] In conjunction with the first aspect, the pre-tensioning mechanism may optionally be a pre-tensioning spring.

[0020] In conjunction with the first aspect, optionally, the formula for calculating the jacking distance of the pipe jacking machine is:

[0021] L=C×N×K,

[0022] In the formula, L is the jacking distance of the pipe jacking machine; C is the encoder single pulse conversion coefficient, C=πD / M, where D is the effective outer diameter of the measuring wheel, M is the number of pulses per revolution of the encoder; N is the number of pulses for pipe section jacking; and k is the calibration compensation coefficient.

[0023] In conjunction with the first aspect, optionally, the pressure regulating ring is provided with a tightening mechanism, which is used to fix the pressure regulating ring and the regulating rod.

[0024] In conjunction with the first aspect, optionally, the wheel surface of the ranging wheel is a wear-resistant rubber-coated wheel surface or a textured anti-slip wheel surface.

[0025] In conjunction with the first aspect, optionally, the pipe jacking machine jacking distance measuring device further includes a human-machine interface, which is connected to the controller and displays data received from the controller.

[0026] In a second aspect, the present invention provides a measurement method applicable to the pipe jacking machine jacking distance measuring device described in the first aspect, comprising:

[0027] The first measuring component is installed such that the mounting base in the first measuring component is installed near the starting working shaft opening of the pipe jacking machine, and the wheel surface of the measuring wheel forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process.

[0028] The pipe jacking machine is controlled to operate, and as the pipe sections move continuously, the measuring wheel rotates.

[0029] The controller calculates the jacking distance of the first pipe jacking machine based on the output data of the encoder in the first measuring component.

[0030] In conjunction with the second aspect, the measurement method may optionally further include:

[0031] Install the second measuring component, such that the mounting base in the second measuring component is installed near the starting working shaft opening of the pipe jacking machine, and such that the wheel surface of the measuring wheel forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process;

[0032] The controller calculates the jacking distance of the second pipe jacking machine based on the output data of the encoder in the second measurement component. When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds a preset difference threshold, a slippage signal or an abnormal alarm signal is output.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The pipe jacking machine jacking distance measuring device of the present invention has a simple structure, does not require modification of the internal structure of the pipe jacking machine, is suitable for various pipe jacking construction scenarios, is easy to install and disassemble, and causes little construction interference.

[0035] This invention can directly measure the actual displacement of pipe sections without manual measurement, thus avoiding human error.

[0036] This invention can continuously output the jacking distance and speed (which can be obtained from the pulse frequency), which is beneficial for closed-loop control and recording.

[0037] This invention, by setting up a first measurement component and a second measurement component with identical structures, and utilizing the simultaneous operation of the two, can achieve dual-wheel redundancy and consistency verification, and can identify anomalies such as slippage and jamming. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0039] Figure 1This is a schematic diagram of the overall installation of the pipe jacking machine jacking distance measuring device at the opening of the working shaft in one embodiment of the present invention;

[0040] Figure 2 This is an exploded schematic diagram of a pipe jacking machine jacking distance measuring device in one embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the process for calculating the jacking distance of a pipe jacking machine in one embodiment of the present invention;

[0042] In the diagram: 1. Mounting base, 2. Adjusting rod, 3. Pressure adjusting ring, 4. Pre-tightening mechanism, 5. Distance measuring wheel, 6. Encoder fixing plate, 7. Encoder, 8. Tightening mechanism. Detailed Implementation

[0043] 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 some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0044] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0045] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0046] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] Example 1

[0049] like Figures 1-2 As shown, this embodiment of the invention provides a pipe jacking machine jacking distance measuring device, including: a controller and a first measuring component;

[0050] The first measurement component includes:

[0051] The measuring wheel 5 has its wheel surface used to form friction transmission contact with the outer surface of the pipe section that moves during the jacking process;

[0052] Encoder 7 is coaxially connected to the measuring wheel 5 and is used to output pulse signals corresponding to the rotation of the measuring wheel 5;

[0053] The encoder mounting plate 6 has its first end connected to the encoder 7. In the specific implementation, the first end of the encoder mounting plate 6 and the encoder 7 are provided with a number of circular mounting holes at corresponding positions. The circular mounting holes are used to install the encoder 7 onto the encoder mounting plate 6.

[0054] Mounting base 1 is used to install near the starting working shaft opening of the pipe jacking machine; in specific implementation, the mounting base 1 is provided with several mounting holes for fixing the mounting base 1 to the vicinity of the starting working shaft opening of the pipe jacking machine.

[0055] Adjusting rod 2, one end is fixedly connected to the mounting base 1, and the other end is rotatably connected to the pressure adjusting ring 3; in specific implementation, such as Figure 2 As shown, the mounting base 1 is provided with mounting holes for connecting to the adjusting rod 2;

[0056] The pressure regulating ring 3 is located between the mounting base 1 and the encoder fixing plate 6, and is rotatably connected to the adjusting rod 2, and can rotate relative to the adjusting rod 2; the encoder fixing plate 6 and the pressure regulating ring 3 are provided with mounting holes for fixing the adjusting rod 2, and the mounting holes are used to install the end of the adjusting rod 2, and the two are fixedly connected.

[0057] The pre-tightening mechanism 4 is connected at one end to the pressure regulating ring 3 and at the other end to the encoder fixing plate 6. It is used to apply a pre-tightening force toward the outer surface of the pipe section to the ranging wheel 5 to ensure that the wheel surface is in continuous contact with the outer surface of the pipe section and to suppress slippage.

[0058] The controller is connected to the encoder 7 and calculates the jacking distance of the pipe jacking machine based on the output data of the encoder 7.

[0059] The jacking distance measuring device in the above scheme requires no modification to the internal structure of the pipe jacking machine, is adaptable to various pipe jacking construction scenarios, is easy to install and disassemble, and causes minimal construction interference. Utilizing the frictional transmission contact between the measuring wheel and the outer surface of the moving pipe section during jacking, and in conjunction with an encoder and controller, it can directly measure the actual displacement of the pipe section without manual measurement, avoiding human error, and continuously output the jacking distance and speed (obtainable from the pulse frequency), facilitating closed-loop control and recording.

[0060] In one specific embodiment of the present invention, the pipe jacking machine jacking distance measuring device further includes a second measuring component (not shown in the figure). The structure of the second measuring component is the same as that of the first measuring component, and the encoder 7 in the second measuring component is connected to the controller.

[0061] In the above scheme, by setting up a first and second measuring component with identical structures, and utilizing their simultaneous operation, dual-wheel redundancy and consistency verification can be achieved to identify anomalies such as slippage and jamming. In specific implementation, the first and second measuring components are preferably arranged symmetrically, and the line connecting them is perpendicular to the central axis of the pipe section, in order to improve measurement accuracy.

[0062] In one specific embodiment of the present invention, the controller calculates the first pipe jacking machine jacking distance and the second pipe jacking machine jacking distance based on the output data of encoder 7 in the first measuring component and encoder in the second measuring component, respectively.

[0063] When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds a preset difference threshold, a slippage signal or an abnormal alarm signal will be output.

[0064] In the specific implementation process, such as Figure 3 As shown, two sets of ranging wheels 5 and encoders 7 are arranged on the left and right sides near the starting working shaft of the pipe jacking machine, respectively outputting the jacking distance S1 of the first pipe jacking machine and the jacking distance S2 of the second pipe jacking machine. The controller calculates Δ=|S1-S2| in real time. When Δ exceeds the preset difference threshold, it determines that there is slippage, mud adhesion or wheel surface failure, triggers an alarm, and switches the ranging to a reliable channel or fused value, while recording the abnormal segment.

[0065] In one specific embodiment of the present invention, the pre-tensioning mechanism 4 is a pre-tensioning spring.

[0066] In the above scheme, by setting the pre-tensioning mechanism 4 as a pre-tensioning spring, the structure is simple, the cost is low, and it is easy to promote.

[0067] In one specific embodiment of the present invention, the formula for calculating the jacking distance of the pipe jacking machine is as follows:

[0068] L=C×N×K,

[0069] In the formula, L is the jacking distance of the pipe jacking machine; C is the single-pulse conversion coefficient of encoder 7, C=πD / M, where D is the effective outer diameter of the measuring wheel 5, M is the number of pulses per revolution of encoder 7; N is the number of pulses for pipe section jacking; and k is the calibration compensation coefficient.

[0070] The above scheme provides a specific calculation formula for the jacking distance of the pipe jacking machine, which facilitates implementation.

[0071] In one specific embodiment of the present invention, the pressure regulating ring 3 is provided with a tightening mechanism 8, which is used to fix the pressure regulating ring 3 and the regulating rod 2.

[0072] In the above scheme, when the preload needs to be adjusted, the pressure adjusting ring 3 is rotated, and then the tightening mechanism 8 is used to fix the pressure adjusting ring 3 to the adjusting rod 2, which facilitates the adjustment of the preload and is simple to operate. In specific implementation, the tightening mechanism 8 can be an adjusting bolt. One end of the preload mechanism 4 is connected to one of the tightening mechanisms 8, and the other end of the preload mechanism 4 is connected to the adjusting bolt installed on the encoder fixing plate 6. Preferably, the preload mechanism 4 is parallel to the encoder fixing plate 6.

[0073] In one specific embodiment of the present invention, the wheel surface of the measuring wheel 5 is a wear-resistant rubber-coated wheel surface or a textured anti-slip wheel surface.

[0074] In the above scheme, by setting the wheel surface of the measuring wheel 5 to a wear-resistant rubber-coated wheel surface or a textured anti-slip wheel surface, the friction between the measuring wheel 5 and the tube section can be increased, thereby improving the measurement accuracy.

[0075] In one specific embodiment of the present invention, the pipe jacking machine jacking distance measuring device further includes a human-machine interface, which is connected to the controller and displays data received from the controller.

[0076] In the above scheme, by setting up a human-machine interface, the output data of the controller can be observed in real time, including the jacking distance of the pipe jacking machine, slippage signals or abnormal alarm signals, etc.

[0077] like Figure 3As shown, the method of using the pipe jacking machine jacking distance measuring device in this embodiment of the invention includes:

[0078] (1) Installation and calibration of the device

[0079] Specifically, this includes: installing and calibrating the pipe jacking machine's jacking distance measuring device;

[0080] (2) Initial parameter settings

[0081] Set the initial values ​​for the relevant parameters in the controller;

[0082] (3) Signal acquisition

[0083] Specifically, this includes: forming a friction drive contact between the wheel surface of the measuring wheel and the outer surface of the pipe section moving during the jacking process; as the pipe section moves continuously, it drives the measuring wheel to rotate; the rotation of the measuring wheel drives the encoder to work, so that the encoder outputs a pulse signal corresponding to the rotation of the measuring wheel.

[0084] (4) Displacement conversion

[0085] The controller calculates the jacking distance of the pipe jacking machine based on the pulse signal output by the encoder;

[0086] (5) Dual-channel calculation

[0087] Based on the output signals of the first and second measuring components, the jacking distance S1 of the first pipe jacking machine and the jacking distance S2 of the second pipe jacking machine are output respectively. The controller calculates Δ=|S1-S2| in real time.

[0088] (6) When Δ exceeds the preset difference threshold, it is determined that there is slippage, mud adhesion or wheel surface failure, triggering an alarm and switching the ranging to a reliable channel or fused value, while recording the abnormal segment;

[0089] (7) The controller outputs relevant parameter values ​​via a human-machine interface (HMI).

[0090] use

[0091] Example 2

[0092] This invention provides a measurement method applicable to the pipe jacking machine jacking distance measuring device described in Embodiment 1, comprising:

[0093] The first measuring component is installed such that the mounting base 1 in the first measuring component is installed near the starting working shaft opening of the pipe jacking machine, and the wheel surface of the measuring wheel 5 forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process.

[0094] The pipe jacking machine is controlled to operate, and as the pipe section moves continuously, the measuring wheel 5 rotates.

[0095] The controller calculates the jacking distance of the first pipe jacking machine based on the output data of encoder 7 in the first measuring component.

[0096] The above scheme can directly measure the actual displacement of the pipe section without manual measurement, thus avoiding human error. Furthermore, it can continuously output the jacking distance and speed (obtainable from the pulse frequency), facilitating closed-loop control and recording.

[0097] In one specific embodiment of the present invention, the measurement method further includes:

[0098] Install the second measuring component so that the mounting base 1 in the second measuring component is installed near the starting working shaft opening of the pipe jacking machine, and so that the wheel surface of the measuring wheel 5 forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process.

[0099] The controller calculates the jacking distance of the second pipe jacking machine based on the output data of the encoder 7 in the second measurement component. When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds the preset difference threshold, a slippage signal or an abnormal alarm signal is output.

[0100] Based on the above scheme, by setting up a first measurement component and a second measurement component with the same structure, and utilizing the simultaneous operation of the two, dual-wheel redundancy and consistency verification can be achieved, and abnormalities such as slippage and jamming can be identified.

[0101] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify 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 limiting the scope of protection of the present invention.

[0102] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A device for measuring the jacking distance of a pipe jacking machine, characterized in that, include: Controller and first measurement component; The first measurement component includes: The measuring wheel has its wheel surface used to form frictional transmission contact with the outer surface of the pipe section that moves during the jacking process; An encoder, coaxially connected to the measuring wheel, is used to output a pulse signal corresponding to the rotation of the measuring wheel; An encoder mounting plate, the first end of which is connected to the encoder; Mounting bracket, used for installation near the starting working shaft opening of the pipe jacking machine; One end of the adjusting rod is fixedly connected to the mounting base, and the other end is fixedly connected to the second end of the encoder fixing plate; A pressure regulating ring is located between the mounting base and the encoder fixing plate, and is rotatably connected to the adjusting rod, and can rotate relative to the adjusting rod. The pre-tightening mechanism is connected at one end to the pressure regulating ring and at the other end to the encoder fixing plate, and is used to apply a pre-tightening force toward the outer surface of the pipe section to the measuring wheel; The controller is connected to the encoder and calculates the jacking distance of the pipe jacking machine based on the output data of the encoder.

2. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The jacking distance measuring device for the pipe jacking machine also includes a second measuring component. The structure of the second measuring component is the same as that of the first measuring component, and the encoder in the second measuring component is connected to the controller.

3. The pipe jacking machine jacking distance measuring device according to claim 2, characterized in that: The controller calculates the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine based on the output data of the encoder in the first measurement component and the encoder in the second measurement component, respectively. When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds a preset difference threshold, a slippage signal or an abnormal alarm signal will be output.

4. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The pre-tensioning mechanism is a pre-tensioning spring.

5. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The formula for calculating the jacking distance of the pipe jacking machine is as follows: L=C×N×K, In the formula, L is the jacking distance of the pipe jacking machine; C is the encoder single pulse conversion coefficient, C=πD / M, where D is the effective outer diameter of the measuring wheel, M is the number of pulses per revolution of the encoder; N is the number of pulses for pipe section jacking; and k is the calibration compensation coefficient.

6. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The pressure regulating ring is provided with a tightening mechanism, which is used to fix the pressure regulating ring and the regulating rod.

7. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The wheel surface of the ranging wheel is a wear-resistant rubber-coated wheel surface or a textured anti-slip wheel surface.

8. The pipe jacking machine jacking distance measuring device according to claim 1, characterized in that: The jacking distance measuring device for the pipe jacking machine also includes a human-machine interface, which is connected to the controller and displays data received from the controller.

9. A measurement method applicable to the pipe jacking machine jacking distance measuring device as described in claims 1-8, characterized in that, include: The first measuring component is installed such that the mounting base in the first measuring component is installed near the starting working shaft opening of the pipe jacking machine, and the wheel surface of the measuring wheel forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process. The pipe jacking machine is controlled to operate, and as the pipe sections move continuously, the measuring wheel rotates. The controller calculates the jacking distance of the first pipe jacking machine based on the output data of the encoder in the first measuring component.

10. The measurement method according to claim 9, characterized in that, The measurement method further includes: Install the second measuring component, such that the mounting base in the second measuring component is installed near the starting working shaft opening of the pipe jacking machine, and such that the wheel surface of the measuring wheel forms a friction transmission contact with the outer surface of the pipe section moving during the jacking process; The controller calculates the jacking distance of the second pipe jacking machine based on the output data of the encoder in the second measurement component. When the difference between the jacking distance of the first pipe jacking machine and the jacking distance of the second pipe jacking machine exceeds a preset difference threshold, a slippage signal or an abnormal alarm signal is output.

Images