Self-sensing isolation pile and intelligent disturbance monitoring method thereof

Abstract

The present invention relates to the field of underground engineering, and in particular to a self-sensing isolation pile and an intelligent disturbance monitoring method thereof. The self-sensing isolation pile comprises a steel cage, an FRP tendon unit, a sensor array unit and a conduit; the sensor array unit comprises a plurality of longitudinal prestressed sensors arranged in the longitudinal FRP tendons and a plurality of transverse prestressed sensors arranged in the annular FRP tendons. The present invention arranges the sensor array unit in an entry unit to sense disturbances such as lateral and positive pressures on the isolation pile caused by shield construction, and converts the disturbances into electrical signals or optical signals for transmission and analysis. When the monitored data threshold exceeds the set warning threshold, a warning is issued and shield parameters can be adjusted in time to avoid engineering accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering monitoring, and in particular to a self-sensing isolation pile and a disturbance intelligent monitoring method thereof. Background Art

[0002] During the shield construction excavation process, it will inevitably cause disturbance of the surrounding soil and loss of surrounding soil layers, which will cause a certain amount of settlement of the soil and ground around the shield and a certain amount of horizontal deformation in the direction of soil loss. The adjacent buildings (structures) will be affected by the tunnel shield and produce uneven settlement. Therefore, it is usually a common protection method to set up isolation piles between the shield tunnel and the pile foundations of existing buildings, such as houses, bridges, subway stations, etc. Through physical isolation and support, the impact of shield advancement on existing pile foundations can be reduced, and the deformation and displacement of the strata caused by the shield construction process can be prevented or slowed down, thereby protecting the stability and safety of the surrounding buildings.

[0003] However, most isolation piles currently control soil deformation caused by shield construction by increasing material strength, expanding pile diameter and extending pile length. This method is not effective in controlling deformation and has low efficiency. In addition, although shield tunnel construction generally produces a decompression and unloading effect on the surrounding soil and adjacent buildings, it is actually a dynamic disturbance during the shield construction process, which means that the impact of shield construction on the surrounding soil and adjacent buildings is constantly changing. The existing technology generally uses displacement and settlement monitoring combined with traditional manual inspections to monitor existing building pile foundations. The monitoring results can often only be collected after the building pile foundation is subjected to positive or lateral stress. There is a certain lag and it is impossible to monitor the disturbance in real time.

[0004] Based on the above situation, it is necessary to design a self-sensing isolation pile and its disturbance intelligent monitoring method to solve the above problems. Summary of the invention

[0005] The present invention provides a self-sensing isolation pile and a disturbance intelligent monitoring method thereof, so as to solve the problem that the disturbance state cannot be monitored in real time and there is a hysteresis in the prior art.

[0006] The technical problem solved by the present invention is achieved by adopting the following technical solutions:

[0007] A self-sensing isolation pile, comprising:

[0008] A steel cage (1), the steel cage (1) comprising a plurality of longitudinal steel bars (11) arranged at equal intervals around the circumference and a plurality of groups of annular steel bars (12) connected at equal intervals in the direction in which the longitudinal steel bars (11) extend in length, and a cap (13) is provided at the upper end of the longitudinal steel bars (11);

[0009] An FRP tendon unit (2), the FRP tendon unit (2) comprising a longitudinal FRP tendon (21) arranged in parallel with the longitudinal steel bars (11) in the steel cage (1) and an annular FRP tendon (22) connected to the longitudinal FRP tendon (21), wherein a plurality of the longitudinal FRP tendons (21) are arranged equidistantly along the central axis of the steel cage (1), and a plurality of the annular FRP tendons (22) are arranged equidistantly along the axial direction of the longitudinal FRP tendons (21);

[0010] A sensor array unit (3), the sensor array unit (3) comprising a plurality of longitudinal prestress sensors (31) arranged in the longitudinal FRP tendons (21) and a plurality of transverse prestress sensors (32) arranged in the annular FRP tendons (22), the sensor array unit (3) being used to monitor forward and lateral disturbances caused by shield construction on the FRP tendon unit (2);

[0011] A conduit (4) is made of a flexible composite material and is arranged at a designed position of the steel cage (1) along the arrangement direction of the FRP tendon unit (2) and is used to introduce the FRP tendon unit (2) into the steel cage (1).

[0012] Preferably, it further comprises a data acquisition device (5) for receiving and processing data from the sensor array unit (3), and the output ends of at least two of the transverse prestress sensors (32) and at least two of the longitudinal prestress sensors (31) are connected to the input end of the data acquisition device (5), and the output end of the data acquisition device (5) transmits the collected data to the outside world via an optical fiber transmission cable (51).

[0013] Preferably, the data acquisition device (5) is connected to the inner wall of the FRP tendon unit (2) using an adhesive (6).

[0014] Preferably, the transverse prestress sensor (32) and the longitudinal prestress sensor (31) are both fiber grating sensors, and the data acquisition device (5) is a coupler.

[0015] The present invention also includes a disturbance intelligent monitoring method for a self-sensing isolation pile, based on the above-mentioned self-sensing isolation pile, comprising the following steps:

[0016] S1: isolation pile construction work, installing the sensor array unit (3) and the FRP reinforcement unit (2) into the guide tube (4), and drilling holes and working below the reinforcement cage (1) according to the pile position coordinates in the drawing, and then pouring concrete to complete the isolation pile construction work;

[0017] S2: Disturbance monitoring. When the shield creates external disturbances in the form of positive and lateral pressures on the pile foundation of an existing building during shield construction, the self-sensing element FRP tendon unit (2) deforms, and the deformation is monitored, analyzed and processed through the internal sensor array unit (3);

[0018] S3: Feedback adjustment, integrating the deformation data fed back by the sensor array unit (3) and transmitting it to the intelligent control central module, and transmitting the data to the external device through the intelligent control central module. If the deformation exceeds the warning threshold, an alarm is issued through the warning module, and the shield parameters are adjusted at the same time.

[0019] Preferably, the external device in S3 includes a storage unit, an external terminal and a signal regulator.

[0020] Preferably, the storage unit comprises a first storage module for storing deformation within the warning range and a second storage module for storing deformation outside the warning range.

[0021] The present invention has the following beneficial effects:

[0022] By setting the sensor array unit in the FRP reinforcement unit, the lateral and positive pressure disturbances caused by the shield construction on the isolation piles can be sensed, and these physical quantities can be converted into electrical signals or optical signals for transmission and analysis. When the monitored data threshold exceeds the set warning threshold, an alarm can be issued and the shield parameters can be adjusted in time to avoid engineering accidents.

[0023] Through multiple groups of longitudinal prestressed sensors and multiple groups of transverse prestressed sensors in the sensor array unit, the stress, strain and other parameters at different parts of the isolation piles can be monitored in real time. This distributed perception can provide a more comprehensive understanding of the stress state of the isolation piles and provide more accurate data support for structural design and analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of a partial cross-sectional structure of the sensor array unit provided by the present invention;

[0026] Figure 2 A schematic diagram of the isometric structure of the steel cage provided by the present invention;

[0027] Figure 3 A schematic diagram of a top view of the structure of the connection between the steel cage and the FRP tendon unit provided by the present invention;

[0028] Figure 4 It is a structural schematic diagram of the FRP tendon unit in the present invention;

[0029] Figure 5 It is a front view of the shield construction, isolation pile foundation and the existing overall position relationship provided in the present invention;

[0030] Figure 6 It is a block diagram of the overall system provided in the present invention;

[0031] Figure 7 is a system block diagram of the external device in the present invention;

[0032] Figure 8 A block diagram of the data storage system in the present invention;

[0033] Fig. 9 This is a flow chart of the disturbance monitoring method provided in the present invention.

[0034] In the figure, 1. steel cage; 11. longitudinal steel bars; 12. circular steel bars; 13. cap; 2. FRP tendon unit; 21. longitudinal FRP tendons; 22. circular FRP tendons; 3. sensor array unit; 31. longitudinal prestressed sensor; 32. transverse prestressed sensor; 4. catheter; 5. data acquisition equipment; 51. optical fiber transmission cable; 6. adhesive. DETAILED DESCRIPTION

[0035] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0036] Reference Figure 1-Figure 9 As shown, a self-sensing isolation pile includes a steel cage 1, an FRP bar unit 2, a sensor array unit 3 and a guide tube 4. The steel cage 1 is composed of a plurality of longitudinal steel bars 11 arranged equidistantly around the circumference and a plurality of groups of annular steel bars 12 equidistantly connected to the longitudinal steel bars 11 in the direction of the longitudinal extension. A cap 13 is provided at the upper end of the longitudinal steel bars 11. The diameter of the steel cage 1 can be set according to the surrounding engineering environment of the actual construction, the soil type, the groundwater level, etc., and the longitudinal steel bars 11 and the annular steel bars 12 can be fixed by welding or wire bundling, and can be bundled on site or prefabricated in a factory.

[0037] The FRP tendon unit 2 includes a longitudinal FRP tendon 21 arranged in parallel with the longitudinal steel bars 11 in the steel cage 1 and an annular FRP tendon 22 connected to the longitudinal FRP tendon 21, and a plurality of the longitudinal FRP tendons 21 are arranged equidistantly along the central axis of the steel cage 1, and a plurality of the annular FRP tendons 22 are arranged equidistantly along the axial direction of the longitudinal FRP tendons 21, wherein the longitudinal FRP tendons 21 and the annular FRP tendons 22 can be made of high-strength fibers (such as carbon fibers, glass fibers, aramid fibers, etc.) and polymer matrices (such as epoxy resins, polyester resins, etc.) through pultrusion or other processes, have high strength, can provide the same bearing capacity, and reduce the deadweight of the structure at the same time, and have higher tensile strength and lower elastic modulus than traditional steel bars, which means that it has It is more likely to deform when subjected to external forces. When subjected to lateral pressure, the tendons will produce corresponding deformations according to the magnitude and direction of the force. The FRP tendon unit 2 is set in the steel cage 1 and positioned inside the isolation pile by later concrete pouring. Since there is bonding force between the concrete and the FRP tendons, the two can work together. When the shield is constructed, when subjected to lateral or positive pressure, the concrete will transfer part of the force to the internal tendons. When the pressure acts on the isolation pile, the concrete will deform slightly. This deformation will be transmitted to the FRP tendons through the bonding force, causing the FRP tendons to also produce corresponding deformations, so that the isolation pile can self-perceive external disturbances, and the disturbance situation can be monitored in real time through the sensor array unit 3 set in the FRP tendon unit 2;

[0038] The number of the longitudinal FRP ribs 21 and the annular FRP ribs 22 is usually determined according to the lateral pressure borne by the isolation pile, the size of the pile and the design requirements. Generally speaking, the appropriate number can be determined through structural calculation and simulation analysis. If the pressure is large and the size of the isolation pile is also large, it can be considered to set a plurality of longitudinal FRP ribs 21 and annular FRP ribs 22, and the diameter of the FRP ribs can be 25-30 mm to improve their bearing capacity and perception ability.

[0039] The sensor array unit 3 includes a plurality of longitudinal prestressed sensors 31 arranged in the longitudinal FRP tendons 21 and a plurality of transverse prestressed sensors 32 arranged in the annular FRP tendons 22. The longitudinal prestressed sensors 31 can sense lateral pressure at different angles, and the transverse prestressed sensors 32 can sense pressure at the upper, middle and lower depths of the isolation piles. The sensor array unit 3 is used to comprehensively monitor the forward and lateral disturbances of the FRP tendon unit 2 generated during shield construction, so as to adjust the shield parameters in real time and avoid the occurrence of engineering accidents.

[0040] A conduit 4 made of a flexible composite material is also provided in the arrangement direction of the FRP tendon unit 2, and the conduit 4 can be connected to the steel cage 1, mainly used to introduce the FRP tendon unit 2 into the steel cage 1 and protect the FRP tendon unit 2, wherein the conduit 4 sleeved on the annular FRP tendon 22 can be connected to the conduit 4 sleeved on the longitudinal FRP tendon 21.

[0041] Reference Figure 1 As shown, further, it also includes a data acquisition device 5 for receiving and processing the sensor array unit 3, wherein the number of the longitudinal prestressed sensors 31 and the transverse prestressed sensors 32 can be set to multiple, and the output ends of at least two of the transverse prestressed sensors 32 and at least two of the longitudinal prestressed sensors 31 are connected to the input end of the data acquisition device 5. By grouping the transverse prestressed sensors 32 and the longitudinal prestressed sensors 31, the signal processing can be made more centralized and orderly, and the output of each group of sensors is preliminarily processed and integrated, which reduces the complexity of subsequent processing and improves the overall data processing speed and Efficiency, and if a sensor fails, it will only affect the group it belongs to, and will not cause serious impact on the entire system. By analyzing each group of data separately, it is easier to locate the faulty sensor, which is convenient for timely repair or replacement. The output end of the data acquisition device 5 transmits the collected data to the outside world through the optical fiber transmission cable 51. When the isolation pile is subjected to the pressure disturbance caused by the shield construction, a part of the force will be transmitted to the FRP tendon unit 2, causing the FRP tendon unit 2 to deform. When the FRP tendon unit 2 is deformed, it will cause the physical parameters of the sensor array unit 3 to change, and then the sensor array unit 3 transmits the data to the data acquisition device 5.

[0042] Among them, multiple data acquisition devices 5 are arranged in each longitudinal FRP rib 21, and an independent optical fiber transmission cable 51 is arranged in each longitudinal FRP rib 21, so that an independent signal transmission path can be provided for each optical fiber transmission cable 51, and interference between signals can be reduced. If one of the optical fiber transmission lines has a problem, it will not affect the normal operation of other optical fiber transmission lines, thereby improving the reliability and stability of the system. At the same time, it is relatively easy to conduct subsequent troubleshooting and maintenance, and the optical fiber transmission line with problems can be processed separately.

[0043] Furthermore, the transverse prestress sensor 32 and the longitudinal prestress sensor 31 are both fiber grating sensors, and the data acquisition device 5 is a coupler. The fiber grating sensor has the advantages of high precision, high sensitivity and strong anti-interference ability, and can accurately detect the slight deformation of the FRP tendon unit 2. When the isolation pile is subjected to pressure from the top or bottom of the pile, the longitudinal FRP tendon 21 and the annular FRP tendon 22 will deform. The fiber grating sensor is installed in the FRP tendon unit 2, amplifies the slight changes of the self-sensing element and converts it into a measurable electrical signal, can sense this deformation and transmit the signal to the coupler through the optical fiber. By analyzing the signal changes of the sensor through the coupler, the forward pressure disturbance of the isolation pile can be determined, and the collected disturbance data can be transmitted to the outside world through the optical fiber transmission cable 51.

[0044] Among them, during installation, the transverse prestress sensor 32 and the longitudinal prestress sensor 31 are connected to the coupler and placed in the corresponding FRP tendons, and then the FRP tendon unit 2 is placed in the conduit 4. In order to facilitate installation, the conduit 4 can be divided into multiple sections, and each section is installed in turn during installation. Finally, the conduit 4 outside the transverse prestress sensor 32 is connected to the conduit 4 outside the longitudinal prestress sensor 31, and then the outside of the conduit 4 is led out through the output end of the optical fiber transmission cable 51 and connected to the external device for the external device to read the monitoring data.

[0045] Furthermore, the data acquisition device 5 is connected to the inner wall of the FRP tendon unit 2 with an adhesive 6, which can enhance the connection stability between the data acquisition device 5 and the FRP tendon, ensure that the two will not separate under the action of external stress, and ensure the overall stability of the system, especially under external forces such as lateral pressure generated by shield construction, etc., a firm connection can better transmit and detect stress changes.

[0046] The present invention also provides a method for intelligently monitoring disturbances of a self-sensing isolation pile. The method is implemented based on the above-mentioned self-sensing isolation pile, and the method comprises the following steps:

[0047] S1: Isolation pile construction work, install the sensor array unit 3 and the FRP reinforcement unit 2 into the conduit 4, and drill holes and work under the reinforcement cage 1 according to the pile position coordinates in the drawing, and then pour concrete to complete the isolation pile construction work;

[0048] S2: Disturbance monitoring. When the shield creates external disturbances such as positive and lateral pressure on the pile foundation of an existing building during shield construction, the self-sensing element FRP tendon unit 2 deforms, and the deformation is monitored, analyzed and processed through the internal sensor array unit 3;

[0049] S3: Feedback adjustment, the deformation data fed back by the sensor array unit 3 is integrated and transmitted to the intelligent control central module, and the data is transmitted to the external device through the intelligent control central module. If the deformation exceeds the warning threshold, an alarm is issued through the warning module, and the shield parameters are adjusted at the same time.

[0050] Furthermore, the external devices in S3 include a storage unit, an external terminal and a signal conditioner. The coupler merges the signal of the sensor array unit 3 into the optical fiber transmission cable 51, and transmits the signal to the intelligent control central module. The intelligent control central module is responsible for communication with other subsystems, equipment or superior control systems. After the signal is amplified, filtered and isolated by the signal conditioner, it is displayed to an external terminal, such as a display or a user monitoring interface, and stored in the storage unit for data storage.

[0051] Furthermore, the storage unit includes a first storage module for storing deformation within the warning range and a second storage module for storing deformation outside the warning range. The qualified values ​​within the warning range are stored and can be used as benchmark data to calculate statistical indicators such as average values ​​and standard deviations, which are convenient for subsequent comparative analysis. By accumulating qualified data over a long period of time, it is possible to better understand the parameter range and change trend of the isolation piles under normal conditions, providing a basis for evaluating the overall performance and stability of the isolation piles. By storing unqualified data outside the warning range, the problem can be quickly located and the efficiency of troubleshooting can be improved. There is no need to laboriously search for outliers in a large amount of data, which saves time and energy and facilitates in-depth analysis of unqualified situations, such as analyzing the frequency of occurrence, trend, and association with specific factors of unqualified data, so as to find the root cause of the problem and provide strong support for taking targeted improvement measures.

[0052] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A self-sensing isolation pile, characterized in that: include; A steel cage (1), the steel cage (1) comprising a plurality of longitudinal steel bars (11) arranged at equal intervals around the circumference and a plurality of groups of annular steel bars (12) connected at equal intervals in the direction in which the longitudinal steel bars (11) extend in length, and a cap (13) is provided at the upper end of the longitudinal steel bars (11); An FRP tendon unit (2), the FRP tendon unit (2) comprising a longitudinal FRP tendon (21) arranged in parallel with the longitudinal steel bars (11) in the steel cage (1) and an annular FRP tendon (22) connected to the longitudinal FRP tendon (21), wherein a plurality of the longitudinal FRP tendons (21) are arranged equidistantly along the central axis of the steel cage (1), and a plurality of the annular FRP tendons (22) are arranged equidistantly along the axial direction of the longitudinal FRP tendons (21); A sensor array unit (3), the sensor array unit (3) comprising a plurality of longitudinal prestress sensors (31) arranged in the longitudinal FRP tendons (21) and a plurality of transverse prestress sensors (32) arranged in the annular FRP tendons (22), the sensor array unit (3) being used to monitor forward and lateral disturbances caused by shield construction on the FRP tendon unit (2); A conduit (4) is made of a flexible composite material and is arranged at a designed position of the steel cage (1) along the arrangement direction of the FRP tendon unit (2) and is used to introduce the FRP tendon unit (2) into the steel cage (1).

2. A self-sensing isolation pile according to claim 1, characterized in that: It also includes a data acquisition device (5) for receiving and processing data from the sensor array unit (3), wherein the output ends of at least two of the transverse prestress sensors (32) and at least two of the longitudinal prestress sensors (31) are connected to the input end of the data acquisition device (5), and the output end of the data acquisition device (5) transmits the collected data to the outside world via an optical fiber transmission cable (51).

3. A self-sensing isolation pile according to claim 2, characterized in that: The data acquisition device (5) is connected to the inner wall of the FRP tendon unit (2) using an adhesive (6).

4. A self-sensing isolation pile according to claim 2, characterized in that: The transverse prestress sensor (32) and the longitudinal prestress sensor (31) are both fiber grating sensors, and the data acquisition device (5) is a coupler.

5. A method for intelligently monitoring disturbances of a self-sensing isolation pile, based on a self-sensing isolation pile according to any one of claims 1 to 4, characterized in that: The steps include: S1: isolation pile construction work, installing the sensor array unit (3) and the FRP reinforcement unit (2) into the guide tube (4), and drilling holes and lowering the reinforcement cage (1) according to the pile position coordinates in the drawing, and then pouring concrete to complete the isolation pile construction work; S2: Disturbance monitoring. When the shield creates external disturbances in the form of positive and lateral pressures on the pile foundation of an existing building during shield construction, the self-sensing element FRP tendon unit (2) deforms, and the deformation is monitored, analyzed and processed through the internal sensor array unit (3); S3: Feedback adjustment, integrating the deformation data fed back by the sensor array unit (3) and transmitting it to the intelligent control central module, and transmitting the data to the external device through the intelligent control central module. If the deformation exceeds the warning threshold, an alarm is issued through the warning module, and the shield parameters are adjusted at the same time.

6. The disturbance intelligent monitoring method according to claim 5, characterized in that: The external device in S3 includes a storage unit, an external terminal and a signal regulator.

7. The disturbance intelligent monitoring method according to claim 6, characterized in that: The storage unit includes a first storage module for storing deformation within the warning range and a second storage module for storing deformation outside the warning range.

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