Foundation pit surrounding environment micro-disturbance control system

Abstract

A foundation pit surrounding environment micro-disturbance control system comprises a double-outlet-rod hydraulic oil cylinder, a controller and a computer. The double-outlet-rod hydraulic oil cylinder is arranged between the inner ring beam and the outer ring beam and comprises an outer shell and hydraulic oil cylinders arranged in the outer shell side by side; the controller is electrically connected with the FBG pressure sensor, an optical fiber demodulator is arranged in the controller, the optical fiber demodulator receives the optical signal and converts the optical signal into a pressure signal, and the controller converts the pressure signal into a pressure value according to a pre-calibrated pressure-wavelength curve and transmits the pressure value to a computer; and the computer is used for controlling hydraulic drive in the hydraulic oil cylinder according to the received pressure value. The optical fiber Bragg grating (FBG) pressure sensor is directly embedded into the inner wall of an oil cylinder cavity, all-optical sensing and transmission of pressure signals are achieved, the electro-hydraulic conversion link of a traditional pressure transmitter is eliminated, and an optical-mechanical-hydraulic coupling model is finally established through an optical-hydraulic direct drive interface, an optical fiber signal transmission system and an anti-interference design.

Description

Technical Field

[0001] This application relates to the field of foundation pit construction technology, specifically to a micro-disturbance control system for the surrounding environment of a foundation pit. Background Technology

[0002] Excavation and unloading of soil within a foundation pit can cause deformation of the surrounding soil, necessitating continuous support from a retaining structure to minimize impact on sensitive buildings and structures. Electro-hydraulic servo support systems, mounted on the pit sidewalls, serve both detection and support functions. However, traditional electro-hydraulic servo support systems suffer from two major drawbacks: firstly, response delay due to signal transmission delay caused by the electro-hydraulic conversion process; and secondly, insufficient control precision due to the nonlinear characteristics of the hydraulic system, leading to control errors and making it difficult to meet millimeter-level deformation control requirements. Traditional hydraulic jacks may also exhibit slow response speeds and insufficient long-term stability. This is particularly problematic for critical infrastructure projects in sensitive construction environments, such as deep foundation pit projects near subway tunnels or historical buildings, where high standards for controlling surrounding ground settlement are required. Utility Model Content

[0003] The purpose of this invention is to provide a micro-disturbance control system for the surrounding environment of a foundation pit. By constructing a distributed fiber optic-servo collaborative network, a closed loop of "perception-decision-command" is achieved, enabling the hydraulic cylinder to provide stable support for the foundation pit support system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A micro-disturbance control system for the surrounding environment of a foundation pit, characterized in that it includes a double-outlet hydraulic cylinder, a controller, and a computer;

[0006] Dual-rod hydraulic cylinders: These are strictly symmetrical devices arranged between the inner and outer ring beams. They include an outer housing and hydraulic cylinders arranged side-by-side within the outer housing. The output ends of both hydraulic cylinders are connected to the same push rod. The push rod is tightly fitted against the side wall of the outer ring beam, and the center of the push rod coincides with the center of the outer ring beam on the same horizontal line. An FBG pressure sensor is embedded at the bottom of the hydraulic cylinder to realize fiber optic sensing and transmission of pressure signals, transmitting the pressure value to the controller via optical signals.

[0007] Controller: Electrically connected to the FBG pressure sensor, with a built-in fiber optic demodulator. The fiber optic demodulator receives optical signals and converts them into pressure signals. The controller converts the pressure signals into pressure values ​​according to the pre-calibrated pressure-wavelength curve and transmits them to the computer.

[0008] Computer: Controls the hydraulic drive in the hydraulic cylinder according to the received pressure value, so that the cylinder pressure value is kept within 31.5*0.75MPa and the axial thrust value is kept within 2000*0.75kN.

[0009] More preferably, the double-rod hydraulic cylinder has a cylinder diameter of 80mm, a cylinder diameter of 45mm, a stroke of ±100mm, and a maximum output force of 200kN.

[0010] Furthermore, the fiber optic demodulator has a built-in photodetector that converts optical signals into electrical signals, and the output rods in the dual-output hydraulic cylinder are symmetrically arranged above and below the outer ring beam via ADC digitization.

[0011] In addition, the bottom of the hydraulic cylinder is machined with a micro-groove with a width of 0.3mm and a depth of 0.2mm using a five-axis laser engraving machine. This micro-groove is used to install the FBG pressure sensor. The micro-groove is located on the inner wall of the oil inlet chamber away from the output end of the hydraulic cylinder. Each hydraulic cylinder is equipped with one FBG pressure sensor, which are symmetrically arranged relative to the hydraulic cylinder.

[0012] A method for operating a micro-disturbance control system for the surrounding environment of a foundation pit, characterized by the following steps:

[0013] The FBG pressure sensor receives pressure signals from the hydraulic cylinder, achieving full optical sensing of the pressure signal. It converts the pressure signal into an optical signal, i.e., a wavelength signal, and transmits the optical signal to the fiber optic demodulator of the controller. The fiber optic demodulator converts the optical signal into a pressure signal, i.e., an electrical signal. The controller converts the electrical signal into a pressure value according to a pre-calibrated pressure-wavelength curve and displays it on the computer. The computer outputs a signal to drive the servo valve, adjusting the hydraulic oil flow and pressure, and pushing the piston of the cylinder to move, keeping the cylinder pressure value within 31.5*0.75MPa and the axial thrust value within 2000*0.75kN. A light-mechanical-hydraulic coupling model is established to achieve precise mapping of fiber optic strain, hydraulic pressure, and mechanical deformation.

[0014] Compared with the prior art, this utility model has the following features and beneficial effects:

[0015] This application addresses the issues of lag in response and insufficient control precision in traditional electro-hydraulic servo supports by designing a dual-rod symmetrical hydraulic cylinder (80mm cylinder diameter / 45mm rod diameter, ±100mm stroke). The nonlinearity of output force is eliminated through the equal cross-sectional area structure of the dual piston rods. A fiber Bragg grating (FBG) pressure sensor is directly embedded into the inner wall of the cylinder cavity using five-axis laser engraving and micro-welding technology, achieving full optical sensing and transmission of pressure signals and eliminating the electro-hydraulic conversion link of traditional pressure transmitters.

[0016] This application constructs a distributed fiber-optic-servo collaborative network to achieve a closed loop of "perception-decision-command". Through the design of a dual-rod symmetrical hydraulic cylinder, the development of a high-precision sensing system and control modules, and through the optical-liquid direct drive interface, fiber optic signal transmission system and anti-interference design, an optical-mechanical-liquid coupling model is finally established to achieve accurate mapping of fiber optic strain, hydraulic pressure and mechanical deformation, providing a more refined solution for deep foundation pit construction in urban sensitive environments. Attached Figure Description

[0017] Figure 1 This is a simplified diagram of the double-rod hydraulic cylinder involved in this application;

[0018] Figure 2 This application is illustrated with specific application diagrams.

[0019] Figure 3 This is a diagram illustrating the working signal transmission involved in this application.

[0020] Reference numerals: 1-Double-rod hydraulic cylinder; 11-Outer housing; 12-Hydraulic cylinder; 13-Push rod; 2-Controller; 3-Computer; 4-Inner ring beam; 5-Outer ring beam; 6-FBG pressure sensor. Detailed Implementation

[0021] To make the technical means, innovative features, objectives and effects of this utility model easier to understand, the utility model will be further described below.

[0022] The embodiments described herein are specific implementations of this utility model, used to illustrate the concept of this utility model. They are all illustrative and exemplary, and should not be construed as limiting the implementation methods or scope of this utility model. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0023] Example 1

[0024] A micro-disturbance control system for the surrounding environment of a foundation pit, such as Figures 1-3 As shown, it includes a double-rod hydraulic cylinder 1, a controller 2, and a computer 3;

[0025] Double-rod hydraulic cylinder 1: A strictly symmetrical device, arranged between the inner ring beam 4 and the outer ring beam 5, including an outer housing 11 (mainly used to transmit the force of adjacent hydraulic cylinders 12 so as to evenly transmit the force to the outer ring beam 5) and hydraulic cylinders 12 arranged side by side in the outer housing 11. The output ends of the two hydraulic cylinders 12 are connected to the same push rod 13. The push rod 13 is set tightly against the side wall of the outer ring beam 5, and the center of the push rod 13 and the center of the outer ring beam 5 coincide on the same horizontal line. An FBG pressure sensor 6 (fiber Bragg grating pressure sensor) is embedded at the bottom of the hydraulic cylinder 12 to realize the fiber optic sensing and transmission of pressure signals, and transmit the pressure value to the controller 2 through optical signals.

[0026] Controller 2: Electrically connected to FBG pressure sensor 6 via wired connection, with a built-in fiber optic demodulator. The fiber optic demodulator receives optical signals (fiber optic signals) and converts them into pressure signals. Controller 2 converts the pressure signals into pressure values ​​according to a pre-calibrated pressure-wavelength curve and transmits them to computer 3. Specifically, the fiber optic demodulator has a built-in photodetector that converts the optical signals into electrical signals and digitizes them via an ADC (analog-to-digital converter). The output rods in the double-rod hydraulic cylinder 1 are symmetrically arranged above and below the outer ring beam 5.

[0027] The working principle of a fiber Bragg grating (FBG) pressure sensor: An FBG sensor reflects light of a specific wavelength through a grating. When the external pressure changes, the period and refractive index of the grating change, causing a shift in the reflected wavelength. This wavelength change can be detected by a demodulator and converted into a corresponding pressure or strain value.

[0028] Computer 3: Electrically connected to the controller via a wired connection, it controls the hydraulic drive in the hydraulic cylinder 12 according to the received pressure value, so that the cylinder pressure value is kept within 31.5*0.75MPa and the axial thrust value is kept within 2000*0.75kN.

[0029] In this embodiment, the double-rod hydraulic cylinder 1 has a cylinder diameter of 80mm, a cylinder diameter of 45mm, a stroke of ±100mm, and a maximum output force of 200kN, which can be extended to the 500kN level.

[0030] In this embodiment, the bottom of the hydraulic cylinder 12 is machined with a microgroove with a width of 0.3mm and a depth of 0.2mm by a five-axis laser engraving machine for installing the FBG pressure sensor 6. The microgroove is located on the inner wall of the oil inlet chamber away from the output end of the hydraulic cylinder 12. Each hydraulic cylinder 12 is equipped with an FBG pressure sensor 6, which is symmetrically arranged relative to the hydraulic cylinder 12.

[0031] Example 2

[0032] Based on Example 1, the FBG pressure sensor and the double-rod hydraulic cylinder 1 are arranged in a row around the perimeter of the foundation pit for real-time monitoring to ensure that the cylinder pressure and axial thrust of the double-rod hydraulic cylinder 1 are kept within 75%. The double-rod hydraulic cylinder is driven to adjust the support force according to the signal command to control the foundation pit deformation within ±0.5mm. The foundation pit deformation needs to be detected in conjunction with the foundation pit deformation monitoring system. The fiber optic signal transmission adopts all-optical repeater technology to avoid noise introduced by electrical signal conversion. The fiber optic signal is connected to the servo actuator controller to realize the control of the servo actuator itself.

[0033] The Fiber Bragg Grating (FBG) pressure sensor adopts a direct embedding design. Microgrooves (0.3mm wide × 0.2mm deep) are pre-machined on the inner wall of the cylinder. The microgrooves are machined using a five-axis laser engraving machine (accuracy ±5μm). The FBG sensor (center wavelength 1550nm) is encapsulated on the front cavity wall of the cylinder using laser micro-welding technology (weld width 0.2mm). In the dual-rod cylinder, one FBG pressure sensor is arranged on each side of the cylinder. The dual FBG pressure sensors enable redundant monitoring, whereas traditional cylinders only have single-sided sensing.

[0034] The optical-hydraulic direct drive interface allows the fiber Bragg grating (FBG) pressure sensor to be directly embedded in the oil inlet chamber of the cylinder (range 0~40MPa, wavelength demodulation frequency 1kHz), enabling all-optical sensing of pressure signals.

[0035] The controller has a built-in optical interface module. The optical signal (wavelength) is transmitted to the controller's optical interface module through single-mode / multimode optical fiber, which can effectively avoid electromagnetic interference. Specifically, the optical fiber signal transmission adopts all-optical repeater technology to avoid noise introduced by electrical signal conversion. The controller converts the wavelength offset into the actual pressure value according to the pre-calibrated pressure-wavelength relationship curve and displays it on the computer.

[0036] Computer execution: Drive the double-outlet hydraulic cylinder to adjust the support force according to the signal command, control the deformation of the foundation pit within ±0.5mm, and dynamically adjust the parameters according to the real-time pressure data to adapt to changes, ultimately forming a closed-loop feedback.

[0037] Example 3

[0038] Based on Example 1, this example provides a method for operating a micro-disturbance control system for the surrounding environment of a foundation pit, including the following steps.

[0039] The FBG pressure sensor 6 receives pressure signals from the hydraulic cylinder 12, achieving full optical sensing of the pressure signal. It converts the pressure signal into an optical signal, i.e., a wavelength signal, and transmits the optical signal to the fiber optic demodulator of the controller 2. The fiber optic demodulator converts the optical signal into a pressure signal, i.e., an electrical signal. The controller converts the electrical signal into a pressure value according to the pre-calibrated pressure-wavelength curve and displays it on the computer 3. The computer 3 outputs a signal to drive the servo valve, adjust the hydraulic oil flow and pressure, and push the cylinder piston to move, keeping the cylinder pressure value within 31.5*0.75MPa and the axial thrust value within 2000*0.75kN. A light-mechanical-hydraulic coupling model is established to achieve accurate mapping of fiber optic strain, hydraulic pressure, and mechanical deformation.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A system for controlling micro-disturbance of a foundation pit peripheral environment, characterized in that: It comprises a double-out-rod hydraulic cylinder (1), a controller (2) and a computer (3). The double-out-rod hydraulic cylinder (1) is a strictly symmetrical device, which is arranged between the inner ring beam (4) and the outer ring beam (5) and comprises an outer shell (11) and hydraulic cylinders (12) arranged side by side in the outer shell (11). The output ends of the two hydraulic cylinders (12) are connected with the same top rod (13), the top rod (13) is arranged in close contact with the side wall of the outer ring beam (5), and the top rod (13) and the center of the outer ring beam (5) coincide on the same horizontal line. The FBG pressure sensor (6) is embedded in the inner wall at the bottom of the hydraulic cylinder (12), realizing optical fiber sensing and transmission of pressure signals, and transmitting the pressure value to the controller (2) through optical signal transmission. The controller (2) is electrically connected with the FBG pressure sensor (6) and is internally provided with a fiber demodulator. The fiber demodulator receives optical signals and converts them into pressure signals. The controller (2) converts the pressure signals into pressure values according to the pre-calibrated pressure-wavelength curve and transmits them to the computer (3). The computer controls the hydraulic drive in the hydraulic cylinder (12) according to the received pressure value, so that the cylinder pressure value is kept within 31.5*0.75MPa and the axial thrust value is kept within 2000*0.75kN.

2. The system for controlling micro-disturbance of the environment around a foundation pit according to claim 1, characterized in that: The double-out-rod hydraulic cylinder (1) has a cylinder diameter of 80mm, a cylinder diameter of 45mm, a stroke of ±100mm and a maximum output of 200kN.

3. The system for controlling micro-disturbance of the environment around a foundation pit according to claim 1, characterized in that: The fiber demodulator is internally provided with a photoelectric detector, which converts optical signals into electrical signals and digitizes the output rod in the double-out-rod hydraulic cylinder (1) relative to the horizontal center line of the outer ring beam (5) through ADC.

4. The system for controlling micro-disturbance of the environment around a foundation pit according to claim 1, characterized in that: The bottom of the hydraulic cylinder (12) is engraved with a micro groove with a width of 0.3mm and a depth of 0.2mm, which is used for installing the FBG pressure sensor (6).

5. The system for controlling micro-disturbance of the environment around a foundation pit according to claim 4, characterized in that: The micro groove is located on the oil inlet cavity and the inner wall surface of the hydraulic cylinder (12) away from the output end, and one FBG pressure sensor (6) is arranged on each hydraulic cylinder (12) and symmetrically arranged relative to the hydraulic cylinder (12).

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