A method for measuring the deformation of floor heave in soft rock roadway

Abstract

The application belongs to the technical field of length and linear dimension measurement, and discloses a kind of measurement method for soft rock roadway floor heave deformation, comprising: reference target and reflection target are arranged on roadway roof and floor;Coaxial dual-wavelength high-frequency amplitude modulation laser beam is emitted, and original phase difference and light intensity are obtained by demodulation;Phase correction amount is calculated according to light intensity ratio and medium scattering model, phase difference is corrected, and absolute distance is calculated;Rigid body displacement decoupling matrix is constructed according to reference target distance change;Inverse matrix of decoupling matrix is used to correct coordinates and extract floor net uplift displacement amount;Continuous deformation profile is reconstructed by cubic spline interpolation fitting, the application uses dual-wavelength attenuation ratio to compensate medium scattering phase lag, and uses coordinate inverse transformation to strip measurement reference displacement intervention, which improves the accuracy of floor heave measurement under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of length and linear dimension measurement technology, and more specifically, to a method for measuring the floor bulge deformation in soft rock tunnels. Background Technology

[0002] In underground engineering and mining construction, accurately measuring the floor bulge deformation of soft rock tunnels is crucial for length and linear dimension metrology. Existing non-contact measurement methods typically involve emitting a high-frequency amplitude-modulated laser beam towards target points on the surface to be measured, determining the absolute distance between these points, and then fitting and reconstructing the three-dimensional morphology of the tunnel cross-section based on the measurement results. However, during the excavation of soft rock tunnels and the use of underground structures, a large amount of suspended dust and highly humid water mist particles are usually present within the tunnel. These suspended particles cause strong Mie scattering of propagating light waves, resulting in nonlinear phase lag in the amplitude-modulated light signal and significant attenuation of the echo energy. Conventional optical... Measurement methods typically rely on uniform and clean air environments for measurement, lacking means to compensate for phase lag caused by scattering during light wave propagation in real time. Consequently, the calculated absolute distance is prone to deviation and drift. On the other hand, the measuring host is generally fixed to the tunnel roof or suspended platform. As the soft surrounding rock undergoes rheological and stress changes, the roof and side rock mass may experience overall convergence or displacement, causing the measurement origin to change position and angle. In this case, the measured distance change also includes the influence caused by the movement of the measurement reference, making it difficult to accurately separate the true normal uplift displacement of the floor surface.

[0003] Besides the objective limitations of measurement hardware and physical environment, existing signal processing and control methods also have shortcomings. For example, Chinese invention patent CN108303702B discloses a phase-based laser ranging system and method, which eliminates phase ambiguity by matching the phase ranging sub-units arranged in an array with the geometric space range. However, this scheme is entirely based on the premise of clean air medium and fixed measurement benchmark. It cannot sense and correct the nonlinear phase lag of light waves caused by high concentration of suspended dust and water mist scattering, and cannot cope with the spatial translation and attitude deflection of the measurement host due to the rheology of the surrounding rock.

[0004] Therefore, how to reduce the influence of scattering by the suspended medium on the laser ranging phase, eliminate the drift of the measurement benchmark caused by the overall displacement of the roof and side rock mass, and accurately obtain the continuous deformation profile of the roadway floor have become technical problems that need to be solved. Summary of the Invention

[0005] To address the problems in the background art, the present invention provides a method for measuring the floor heave deformation in soft rock roadways, comprising the following steps:

[0006] Step S1: Establish a local measurement coordinate system on the section to be measured in the soft rock tunnel. Install three non-collinear steady-state reference targets on the top plate and the stable rock mass surfaces on both sides of the section to be measured, and install multiple bottom heave reflection targets on the bottom plate section to be measured.

[0007] Step S2: The measurement host suspended above the cross section to be measured emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams to each steady-state reference target and each bottom reflection target, collects echo signals and demodulates to obtain the original phase difference of the main wavelength, the echo intensity of the main wavelength and the echo intensity of the secondary wavelength.

[0008] Step S3: Determine the wavelength intensity attenuation ratio based on the ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; calculate the phase lag correction amount based on the medium scattering model including the medium scattering correction coefficient to correct the original phase difference of the main wavelength; and calculate the absolute distance from the measuring host to each target.

[0009] Step S4: Based on the absolute distance changes of each steady-state reference target at different measurement times, the translation vector and rotation matrix of the measuring host are solved by the trilateration algorithm to construct the rigid body displacement decoupling matrix of the section to be measured.

[0010] Step S5: Apply an inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement moment using the inverse matrix of the rigid body displacement decoupling matrix, strip away the spatial displacement of the measurement host, and calculate the true spatial coordinates and the net bulge displacement along the normal of the bottom plate.

[0011] Step S6: Use cubic spline interpolation algorithm to fit the net bulge displacement of each bottom bulge reflection target, and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section.

[0012] Preferably, in step S2, when emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, the following sub-steps are included: Step S21, emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam with a main wavelength of 650nm, a secondary wavelength of 808nm, and a modulation frequency of 15MHz, the main wavelength and the secondary wavelength are converged by a coaxial collimating optical system and then directed in parallel towards each steady-state reference target and each bottom-bump reflection target; Step S22, receiving the echo signal reflected by the target through a photodetector, and extracting the original phase difference of the main wavelength, the echo intensity of the main wavelength, and the echo intensity of the secondary wavelength through a narrowband frequency-selective amplifier circuit and a mixer demodulation circuit.

[0013] Preferably, in step S3, when calculating the phase lag correction based on the medium scattering model including the medium scattering correction coefficient, the following sub-steps are included: Step S31, calculating the wavelength intensity attenuation ratio. The ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; Step S32, calculate the phase lag correction caused by scattering from the suspended medium according to the following formula. : ,in, This is the phase lag correction amount. The wavelength-intensity attenuation ratio. To obtain the determined medium scattering correction coefficient based on the roadway aerosol calibration curve; step S33, subtract the phase lag correction amount using the original phase difference of the dominant wavelength. The corrected phase shift is obtained, and the absolute distance is calculated based on the corrected phase shift.

[0014] Preferably, in step S33, when calculating the absolute distance from the measuring host to each target: the corrected phase shift is multiplied by the speed of light in vacuum, and the resulting product is divided by the product of four times pi and the laser modulation frequency to calculate the absolute distance from the measuring origin to each steady-state reference target and each bottom-reflection target; wherein, the speed of light in vacuum used is 3 × 10⁻⁶. 8 m / s, laser modulation frequency is 15MHz.

[0015] Preferably, in step S1, three steady-state reference targets are installed at the central axis of the roof of the section to be measured, the stable rock layer on the left side, and the stable rock layer on the right side, respectively. The three steady-state reference targets form a non-collinear triangular ranging reference surface in space. In step S4, the absolute distances between the three steady-state reference targets at the initial time and the current measurement time are used to solve the three translational degrees of freedom components and three rotational degrees of freedom angular displacements generated by the measuring host relative to the stable rock layer through the trilateration algorithm, thereby constructing a fourth-order isomorphic tunnel section rigid body displacement decoupling matrix containing translation vectors and rotation matrices.

[0016] Preferably, in step S5, when applying the inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement time, the following sub-steps are included: Step S51, obtain the inverse matrix of the rigid body displacement decoupling matrix of the tunnel section, and then multiply the inverse matrix with the four-dimensional homogeneous original measurement coordinate column vector of each bottom bulge reflection target to derive the real spatial coordinate column vector after the rigid body translation and rotation intervention of the stripping measurement host suspension platform; Step S52, take the coordinate axis parallel to the normal direction of the bottom plate as the deformation extraction axis, subtract the real normal coordinate value calculated at the current measurement time from the normal coordinate value of the bottom bulge reflection target at the initial time, and obtain the net bulge displacement of each bottom bulge reflection target.

[0017] Preferably, in step S6, when using the cubic spline interpolation algorithm to fit and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section, the following sub-steps are included: Step S61, taking the lateral position coordinates of each bottom bulge reflection target as the independent variable and the corresponding net bulge displacement as the dependent variable, a cubic polynomial interpolation function is established within the lateral interval formed by adjacent bottom bulge reflection targets; Step S62, setting natural boundary conditions to solve the coefficients of each order of the cubic polynomial interpolation function, fitting the continuous bottom bulge deformation curve spanning the entire bottom plate test section, and solving for the geometric extreme points where the first derivative of the continuous bottom bulge deformation curve is zero, outputting the maximum bottom bulge bulge amount of the bottom plate of the test section and the lateral position coordinates of the occurrence of the maximum bottom bulge bulge amount.

[0018] Preferably, the medium scattering correction coefficient The retrieval and determination method is as follows: a media scattering calibration database corresponding to different dust mass concentrations and relative humidityes is pre-stored inside the measuring host; while emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, dust mass concentration data and relative humidity data of the current cross-section to be measured are collected by an environmental sensor integrated on the surface of the measuring host, and bilinear interpolation is performed in the media scattering calibration database to dynamically retrieve the media scattering correction coefficient that matches the current state of suspended aerosols in the roadway. .

[0019] Preferably, when acquiring echo signals in step S2, if the intensity of the main wavelength echo or the intensity of the secondary wavelength echo obtained by demodulation is lower than the preset effective threshold for light intensity reception, it is determined that the current optical path is interfered with by a sudden high concentration of dust. At this time, the measuring host automatically increases the laser emission driving current to increase the output optical power, and when the light intensity recovers to above the effective threshold for light intensity reception, the phase lag correction and absolute distance calculation in step S3 are started.

[0020] Preferably, after reconstructing the continuous floor heave deformation profile of the test section floor plate in step S6, a floor plate instability early warning is performed: the calculated maximum floor heave amount is compared with the preset allowable deformation critical threshold of the roadway floor plate. If the maximum floor heave amount exceeds the allowable deformation critical threshold, or the maximum value of the local curvature of the continuous floor heave deformation curve exceeds the preset floor plate bending stress concentration threshold, a floor heave early warning signal indicating that the test section floor plate has an instability risk and a corresponding floor plate bottom anti-arch support location suggestion are generated and output.

[0021] The embodiments of the present invention have at least the following beneficial effects:

[0022] 1. In the measurement of the floor deformation of soft rock tunnels, a coaxial dual-wavelength high-frequency amplitude-modulated laser beam is used for distance measurement. The original phase difference of the main wavelength is corrected according to the attenuation difference of the echo intensity of the two wavelengths. This can reduce the phase lag caused by suspended dust and water mist scattering. As a result, the influence of complex tunnel environment on the absolute distance calculation results can be reduced, making the optical distance measurement under high dust and high humidity conditions more stable and accurate.

[0023] 2. By setting non-collinear steady-state reference targets in the stable areas of the roadway roof and sides, and using the rigid body displacement decoupling matrix to correct the measurement coordinates of the bottom heave reflection target, the measurement error caused by the translation or rotation of the measuring host along the roof and side rock can be eliminated. The corrected coordinates can more accurately reflect the heave displacement generated by the floor itself along the normal direction, avoiding misjudging the movement of the measurement reference as bottom heave deformation.

[0024] 3. The ranging error caused by medium scattering is first compensated by phase correction, and then the rigid body displacement is decoupled using the corrected absolute distance. This provides more accurate distance data for coordinate correction, which can reduce the influence of ranging error on the rigid body displacement decoupling matrix and prevent the distance deviation in the previous stage from being transmitted and amplified in subsequent coordinate transformations, thereby improving the reliability of the bottom deformation measurement results. Attached Figure Description

[0025] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings, in which several embodiments of the invention are illustrated by way of example and not limitation, wherein:

[0026] Figure 1 This is a flowchart of the main steps for measuring the tunnel floor deformation according to the present invention;

[0027] Figure 2 This is the closed-loop logic diagram of measurement control and data processing in this invention.

[0028] Figure 3 This is a hardware topology diagram of the measurement host and target node of this invention. Detailed Implementation

[0029] The principles and spirit of the present invention will now be described with reference to several exemplary embodiments in conjunction with the accompanying drawings. It should be understood that these embodiments are provided merely to enable those skilled in the art to better understand and implement the present invention, and are not intended to limit the scope of the present invention in any way. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0030] A method for measuring the floor heave deformation in soft rock tunnels includes the following steps:

[0031] Step S1: Establish a local measurement coordinate system on the section to be measured in the soft rock tunnel. Install three non-collinear steady-state reference targets on the top plate and the stable rock mass surfaces on both sides of the section to be measured, and install multiple bottom heave reflection targets on the bottom plate section to be measured.

[0032] Step S2: The measurement host suspended above the cross section to be measured emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams to each steady-state reference target and each bottom reflection target, collects echo signals and demodulates to obtain the original phase difference of the main wavelength, the echo intensity of the main wavelength and the echo intensity of the secondary wavelength.

[0033] Step S3: Determine the wavelength intensity attenuation ratio based on the ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; calculate the phase lag correction amount based on the medium scattering model including the medium scattering correction coefficient to correct the original phase difference of the main wavelength; and calculate the absolute distance from the measuring host to each target.

[0034] Step S4: Based on the absolute distance changes of each steady-state reference target at different measurement times, the translation vector and rotation matrix of the measuring host are solved by the trilateration algorithm to construct the rigid body displacement decoupling matrix of the section to be measured.

[0035] Step S5: Apply an inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement moment using the inverse matrix of the rigid body displacement decoupling matrix, strip away the spatial displacement of the measurement host, and calculate the true spatial coordinates and the net bulge displacement along the normal of the bottom plate.

[0036] Step S6: Use cubic spline interpolation algorithm to fit the net bulge displacement of each bottom bulge reflection target, and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section.

[0037] Preferably, in step S2, when emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, the following sub-steps are included: Step S21, emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam with a main wavelength of 650nm, a secondary wavelength of 808nm, and a modulation frequency of 15MHz, the main wavelength and the secondary wavelength are converged by a coaxial collimating optical system and then directed in parallel towards each steady-state reference target and each bottom-bump reflection target; Step S22, receiving the echo signal reflected by the target through a photodetector, and extracting the original phase difference of the main wavelength, the echo intensity of the main wavelength, and the echo intensity of the secondary wavelength through a narrowband frequency-selective amplifier circuit and a mixer demodulation circuit.

[0038] Preferably, in step S3, when calculating the phase lag correction based on the medium scattering model including the medium scattering correction coefficient, the following sub-steps are included: Step S31, calculating the wavelength intensity attenuation ratio. The ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; Step S32, calculate the phase lag correction caused by scattering from the suspended medium according to the following formula. : ,in, This is the phase lag correction amount. The wavelength-intensity attenuation ratio. To obtain the determined medium scattering correction coefficient based on the roadway aerosol calibration curve; step S33, subtract the phase lag correction amount using the original phase difference of the dominant wavelength. The corrected phase shift is obtained, and the absolute distance is calculated based on the corrected phase shift.

[0039] Preferably, in step S33, when calculating the absolute distance from the measuring host to each target: the corrected phase shift is multiplied by the speed of light in vacuum, and the resulting product is divided by the product of four times pi and the laser modulation frequency to calculate the absolute distance from the measuring origin to each steady-state reference target and each bottom-reflection target; wherein, the speed of light in vacuum used is 3 × 10⁻⁶. 8 m / s, laser modulation frequency is 15MHz.

[0040] Preferably, in step S1, three steady-state reference targets are installed at the central axis of the roof of the section to be measured, the stable rock layer on the left side, and the stable rock layer on the right side, respectively. The three steady-state reference targets form a non-collinear triangular ranging reference surface in space. In step S4, the absolute distances between the three steady-state reference targets at the initial time and the current measurement time are used to solve the three translational degrees of freedom components and three rotational degrees of freedom angular displacements generated by the measuring host relative to the stable rock layer through the trilateration algorithm, thereby constructing a fourth-order isomorphic tunnel section rigid body displacement decoupling matrix containing translation vectors and rotation matrices.

[0041] Preferably, in step S5, when applying the inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement time, the following sub-steps are included: Step S51, obtain the inverse matrix of the rigid body displacement decoupling matrix of the tunnel section, and then multiply the inverse matrix with the four-dimensional homogeneous original measurement coordinate column vector of each bottom bulge reflection target to derive the real spatial coordinate column vector after the rigid body translation and rotation intervention of the stripping measurement host suspension platform; Step S52, take the coordinate axis parallel to the normal direction of the bottom plate as the deformation extraction axis, subtract the real normal coordinate value calculated at the current measurement time from the normal coordinate value of the bottom bulge reflection target at the initial time, and obtain the net bulge displacement of each bottom bulge reflection target.

[0042] Preferably, in step S6, when using the cubic spline interpolation algorithm to fit and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section, the following sub-steps are included: Step S61, taking the lateral position coordinates of each bottom bulge reflection target as the independent variable and the corresponding net bulge displacement as the dependent variable, a cubic polynomial interpolation function is established within the lateral interval formed by adjacent bottom bulge reflection targets; Step S62, setting natural boundary conditions to solve the coefficients of each order of the cubic polynomial interpolation function, fitting the continuous bottom bulge deformation curve spanning the entire bottom plate test section, and solving for the geometric extreme points where the first derivative of the continuous bottom bulge deformation curve is zero, outputting the maximum bottom bulge bulge amount of the bottom plate of the test section and the lateral position coordinates of the occurrence of the maximum bottom bulge bulge amount.

[0043] Preferably, the medium scattering correction coefficient The retrieval and determination method is as follows: a media scattering calibration database corresponding to different dust mass concentrations and relative humidityes is pre-stored inside the measuring host; while emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, dust mass concentration data and relative humidity data of the current cross-section to be measured are collected by an environmental sensor integrated on the surface of the measuring host, and bilinear interpolation is performed in the media scattering calibration database to dynamically retrieve the media scattering correction coefficient that matches the current state of suspended aerosols in the roadway. .

[0044] Preferably, when acquiring echo signals in step S2, if the intensity of the main wavelength echo or the intensity of the secondary wavelength echo obtained by demodulation is lower than the preset effective threshold for light intensity reception, it is determined that the current optical path is interfered with by a sudden high concentration of dust. At this time, the measuring host automatically increases the laser emission driving current to increase the output optical power, and when the light intensity recovers to above the effective threshold for light intensity reception, the phase lag correction and absolute distance calculation in step S3 are started.

[0045] Preferably, after reconstructing the continuous floor heave deformation profile of the test section floor plate in step S6, a floor plate instability early warning is performed: the calculated maximum floor heave amount is compared with the preset allowable deformation critical threshold of the roadway floor plate. If the maximum floor heave amount exceeds the allowable deformation critical threshold, or the maximum value of the local curvature of the continuous floor heave deformation curve exceeds the preset floor plate bending stress concentration threshold, a floor heave early warning signal indicating that the test section floor plate has an instability risk and a corresponding floor plate bottom anti-arch support location suggestion are generated and output.

[0046] Example 1: During the excavation and maintenance of underground soft rock tunnels, the mass concentration of suspended coal and rock dust in the tunnel air exceeded 150 mg / m³, the relative humidity reached 95%, and it contained high-humidity water mist particles. The main measuring unit was suspended and installed on the steel frame structure at the top of the tunnel, and the measuring origin was... The coordinates are set to The first steady-state reference target was firmly installed on the centrally stabilized rock mass of the top plate, the stable rock layer of the left side slope, and the stable rock layer of the right side slope of the section to be tested. Second steady-state baseline target and the third steady-state benchmark target Three steady-state reference targets form a non-collinear triangular ranging reference surface in space. Four bottom bulge reflection targets are buried at equal intervals of 1.0m on the transverse profile to be measured on the roadway floor, and are sequentially marked as the first bottom bulge reflection target. Second bottom reflective target Third bottom reflective target and the fourth bottom reflective target This led to the establishment of a local three-dimensional measurement coordinate system for soft rock tunnels. Among them, those parallel to the normal direction of the base plate The axis is used as the deformation extraction axis. For the undulating bottom plate profile, the vertical axis of the global coordinate system is set as the overall normal direction of the bottom plate design reference plane. When extracting the heave displacement of each measuring point, the three-dimensional coordinates calculated by each measuring point are orthogonally projected onto the normal direction of the design reference plane, and the projection result is used as a unified normal heave amount.

[0047] At the time of working condition measurement The coaxial dual-wavelength high-frequency amplitude-modulated laser emission module inside the measurement host synchronously emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams toward each target, with the main wavelength... Set to 650nm, secondary wavelength Set to 808nm, modulation frequency Set to 15MHz, the photodetector receives the echo signals reflected from each target, and the photoelectric signal processor demodulates the signals to obtain the first bottom-heavy reflector target. Corresponding principal wavelength original phase difference The value is 1.2566 rad, and the echo intensity of the main wavelength is collected simultaneously. and subwavelength echo intensity The values ​​are 0.40 and 0.80, respectively. At the echo receiver, the beam splitter divides the coaxially incident composite beam into two optical channels according to the wavelength, and projects them onto independent photodetectors sensitive to the corresponding wavelengths. The narrowband frequency-selective amplifier circuit connected to each optical channel sets the center frequency to 15MHz. After filtering out the out-of-band background noise, the signal is sent to the mixer demodulation circuit to mix with the local oscillator signal and down-convert to a low-frequency intermediate frequency signal. The echo intensity amplitude and phase shift parameters corresponding to the main wavelength and the secondary wavelength are extracted respectively.

[0048] The photoelectric signal processor calculates the wavelength light intensity attenuation ratio using the following formula: ,in, To determine the wavelength-intensity attenuation ratio, the measuring host retrieves the medium scattering correction coefficient from the roadway aerosol calibration curves contained in the pre-stored medium scattering calibration database, based on the current dust mass concentration and relative humidity. The data retrieved this time It is 0.05 rad. and Substituting into the medium scattering model, we obtain the phase lag correction caused by scattering from suspended dust and water mist. : Calculated The unit is rad. This logarithmic relationship is determined based on the electromagnetic wave propagation extinction relationship under the single scattering approximation condition. The light intensity attenuation is exponentially related to the medium extinction coefficient. The phase delay caused by the medium is linearly related to the natural logarithm of the ratio of the two wavelength echo light intensities. The medium scattering correction coefficient is determined by laboratory aerosol calibration experiments.

[0049] Using phase lag correction Correcting the original phase difference of the dominant wavelength The corrected phase shift is obtained. : The unit for corrected phase shift is rad, and then... Substitute into the photoelectric ranging equation and solve for the measurement origin. To the first bottom reflective target absolute distance : ,in, The speed of light in a vacuum is 3 × 10⁻⁶. 8 m / s; without medium scattering correction, the calculated original distance is 2.0000m, which differs from the corrected absolute distance by 0.0553m. This difference is the photoelectric ranging drift caused by Mie scattering in the suspended medium.

[0050] When the modulation frequency is 15MHz, the corresponding half-wavelength range is 10m. After the measurement host is installed for the first time, the initial geometric coarse distance is obtained by auxiliary infrared pulse ranging, and the number of integer ambiguity cycles is determined accordingly. In the subsequent continuous monitoring process, the number of integer ambiguity cycles is updated according to the displacement continuity constraint of adjacent sampling cycles. The fine phase shift solution result is added to the return distance corresponding to the integer cycle to obtain the absolute distance from the measurement host to each target.

[0051] At the initial moment The measuring host measured three steady-state reference targets respectively. , and absolute distance , and At the measurement time The absolute distances of the three steady-state baseline targets are updated as follows: , and The trilateration algorithm takes the positions of the three steady-state reference targets in the local three-dimensional measurement coordinate system at the initial moment as the reference. It writes the six absolute distances at the initial moment and the measurement moment into the distance constraint relationship before and after the rigid body transformation. The three translational degrees of freedom components and three rotational degrees of freedom angular displacements generated by the measuring host relative to the stable rock layer are the quantities to be solved. The distance constraint relationship is solved iteratively by least squares. In each iteration, the rotation matrix is ​​updated according to the current angular displacement, and the sum of squared residuals between the calculated distance and the measured absolute distance is used as the convergence criterion to obtain the translation vector and the rotation matrix.

[0052] In this measurement, of the three translational degrees of freedom components The rigid body translation in the axial direction is The algorithm simultaneously calculates the remaining translational components and the three rotational degrees of freedom angular displacements, all of which are close to... The corresponding rotation matrix is ​​approximately the identity matrix, based on which a fourth-order isomorphic tunnel section rigid body displacement decoupling matrix is ​​constructed. : ,in, For a translation vector containing three translational degrees of freedom, This is the rotation matrix constructed based on the angular displacements of the three rotational degrees of freedom.

[0053] At the measurement time The first bottom reflective target The four-dimensional homogeneous original measurement coordinate column vector for Find the inverse matrix of the rigid body displacement decoupling matrix of the fourth-order isomorphic tunnel section. and to Applying an inverse coordinate transformation, we obtain the true spatial coordinate column vector after the rigid body translation and rotation intervention of the stripping measurement host suspension platform: Normal coordinate components in a real space coordinate column vector It is 1.9327m at the initial time. Corresponding normal coordinate components The depth is 2.0000m, from which the first bottom-bulging reflective target is calculated. Net bulge displacement : Calculated The unit is m.

[0054] Using the same phase lag correction and coordinate decoupling methods, the second bottom-bulging reflection target was obtained. Horizontal position coordinates Net bulge displacement at the location The third bottom reflective target Horizontal position coordinates Net bulge displacement at the location The fourth bottom reflective target Horizontal position coordinates Net bulge displacement at the location .

[0055] The lateral position coordinates of each bottom-reflecting target As the independent variable, the corresponding net uplift displacement As the dependent variable, natural boundary conditions are set and a cubic spline interpolation function is constructed: ,in, ; , , and The interpolation polynomial coefficients within the corresponding transverse intervals are used to fit the net bulge displacement of each bulge-reflecting target. This reconstructs the continuous bulge deformation profile spanning the measured section of the base plate. The geometric extrema where the first derivative is zero are then solved for the interpolation function within each transverse interval. In the horizontal range The geometric extreme point corresponding to the maximum value was obtained, and the maximum bottom heave of the bottom plate of the section under test was determined to be 0.1865m, with its lateral coordinates as follows: m, the measurement host outputs the continuous bottom heave deformation profile after the overall displacement of the surrounding rock and the intervention of medium scattering, the maximum bottom heave, the lateral coordinates of the occurrence of the maximum bottom heave, and the corresponding stress concentration extreme value location.

[0056] Example 2: An aerosol dust generator and an ultrasonic water mist spray system were installed in a simulated soft rock tunnel measurement test chamber. The optical dust concentration sensor had a measurement range of 0 to 500 mg / m³ and a measurement accuracy of ±5%. A capacitive humidity sensor was used to adjust the relative humidity, with an adjustment range of 70% to 98% and a control accuracy of ±2%. Hydraulic loading drive mechanisms were installed on the top and sides of the test chamber to simulate the rigid body translational displacement generated by the roof and surrounding rock. The displacement adjustment range was 0 to 50 mm, and the displacement sensor measurement accuracy was 0.01 mm. Four dust mass concentration gradients of 50 mg / m³, 150 mg / m³, 300 mg / m³, and 450 mg / m³ were selected for the experiment. When the dust mass concentration was between 150 mg / m³ and 300 mg / m³ and the relative humidity was 95%, the phase shift drift of the single-wavelength ranging reached the centimeter level, which can be used to verify the measurement results when phase lag correction and rigid body displacement decoupling work together.

[0057] The main measuring unit is suspended on the steel frame structure at the top of the experimental chamber, with the measuring origin at... The coordinates are set to First steady-state reference targets were installed in the top plate and the two side plate stable zones, respectively. Second steady-state baseline target and the third steady-state benchmark target A first bottom bulge reflective target is set on the transverse cross-section to be measured of the base plate. Second bottom reflective target Third bottom reflective target and the fourth bottom reflective target .

[0058] The experiment was divided into four groups. Control group 1 used a 650nm single-wavelength laser for ranging without medium scattering phase correction or rigid body displacement decoupling. Control group 2 used a coaxial dual-wavelength laser (650nm and 808nm) with medium scattering phase correction but without rigid body displacement decoupling. Control group 3 used a coaxial dual-wavelength laser with rigid body displacement decoupling, and the medium scattering correction coefficient was adjusted accordingly. The experimental group used a coaxial dual-wavelength high-frequency amplitude-modulated laser beam with a fixed undercompensation state of 0.02 rad and an overcompensation state of 0.10 rad. 650nm, secondary wavelength 808nm, modulation frequency The frequency was 15MHz, and the calibration value was used in this comparative test. rad, through the fourth-order isomorphic tunnel section rigid body displacement decoupling matrix inverse matrix Correcting the four-dimensional homogeneous original measurement coordinate column vector of the bottom-bump reflective target, the hydraulic loading drive mechanism causes the measurement host suspension platform to move along... The axis generates rigid body translation. m, the base plate lifting mechanism causes the first base plate to reflect the target. Generate true normal uplift displacement m, the above displacement conditions remain unchanged for all four environmental conditions.

[0059] Under various environmental conditions, the experimental group first collected the echo intensity of the dominant wavelength. and subwavelength echo intensity Calculate the wavelength light intensity attenuation ratio Then according to Calculate the phase lag correction and construct a model using the corrected absolute distance. Then according to Perform inverse coordinate transformation to obtain the experimental group's solution values. This value corresponds to the first bottom bulge reflecting target. Net bulge displacement .

[0060] When the dust concentration is 50 mg / m³ and the relative humidity is 75%, the measured values ​​are as follows: , Thus we obtain Under the same input conditions, the measured uplift displacement in control group one was 0.0421m, in control group two it was 0.0553m, and in control group three it was... The undercompensated rad value is 0.0638 m; the experimental group obtained the value after phase lag correction and inverse coordinate transformation. m, and The absolute error between them is 0.0003m.

[0061] When the dust concentration is 150 mg / m³ and the relative humidity is 95%, the measured values ​​are as follows: , ,get The uplift displacements of control groups 1, 2, and 3 were 0.0120 m, 0.0553 m, and 0.0534 m, respectively; the experimental group obtained... m, with an absolute error of 0.0000m.

[0062] When the dust concentration is 300 mg / m³ and the relative humidity is 95%, the measured values ​​are as follows: , ,get The measured uplift displacement in control group 1 was -0.0433m, in control group 2 it was 0.0433m, and in control group 3 it was 0.0398m; the experimental group obtained... m, with an absolute error of 0.0012m. In the three working conditions ranging from 50mg / m³ to 300mg / m³, control group 1 did not perform phase lag correction and rigid body displacement decoupling, and its maximum measurement error was 0.1106m; control group 2 did not separate the rigid body translation of the suspension platform, and control group 3 used a medium scattering correction coefficient that deviated from the calibration value. The calculation results of both retained the corresponding error.

[0063] When the dust concentration is 450 mg / m³ and the relative humidity is 98%, the original received value of the dominant wavelength echo intensity is 0.04, which is lower than the effective threshold of 0.05 for light intensity reception. After the measuring host increases the laser emission drive current, the dominant wavelength echo intensity... The secondary wavelength echo intensity was restored to 0.12. It is 0.60, from which we obtain After the light intensity was restored, phase lag correction and absolute distance calculation were performed. The measured uplift displacements for control groups 1, 2, and 3 were -0.0532m, 0.0321m, and 0.0351m, respectively. The experimental group obtained the following coordinates after inverse transformation: The absolute error was 0.0015m. Among the four working conditions, the maximum absolute error of the test group was 0.0015m.

[0064] In the reconstruction of the continuous bottom heave deformation profile of the bottom plate under test, the experimental group obtained the following results: m、 m、 m and m, the lateral position coordinates of each bottom-reflecting target. As the independent variable, the corresponding net uplift displacement Substituting the cubic spline interpolation function under the natural boundary conditions as the dependent variable: ,in, , , , and The interpolation polynomial coefficients are defined for each lateral interval. The cubic spline interpolation function is established piecewise between adjacent basal reflective targets, including... The horizontal interval; solve for the geometric extrema where the first derivative is zero over all segments: Based on the extreme value results of each segment, the maximum bottom heave of the base plate at this cross-section is determined to be 0.1865m, and the corresponding lateral position coordinates are... m, the measuring host outputs the continuous bottom bulge deformation profile, the maximum bottom bulge, the lateral coordinates of the occurrence of the maximum bottom bulge, and the corresponding stress concentration extreme value location.

[0065] Example 3: A suspended platform is located 50m behind the current soft rock tunnel excavation face. During continuous mining, the mass concentration of suspended dust in the tunnel is... The relative humidity suddenly increased from 100 mg / m³ to 480 mg / m³. Maintaining a 96% accuracy rate, the measuring host is fixed on a suspended platform at the top of the roadway, with the measuring origin... The coordinates are set to The first steady-state reference target was firmly installed on the top plate and the stable rock strata on the left and right sides of the section to be tested. Second steady-state baseline target and the third steady-state benchmark target A first bottom bulge reflection target is set on the cross-section of the base plate to be measured. Second bottom reflective target Third bottom reflective target and the fourth bottom reflective target This led to the establishment of a local three-dimensional measurement coordinate system for soft rock tunnels. Among them, those parallel to the normal direction of the base plate The axis serves as the deformation extraction axis.

[0066] At the time of working condition measurement The high dust laser scattering concentration sensor and the high humidity capacitive humidity sensor, integrated on the surface of the measuring host housing, respectively collect the current cross-section under test. and The photoelectric signal processor retrieves a two-dimensional medium scattering calibration database from the non-volatile memory inside the measurement host. This database was obtained from offline atomized dust calibration experiments. Within the range of dust mass concentration from 0 to 500 mg / m³ and relative humidity from 70% to 98%, the medium scattering correction coefficients are stored with grid steps of 50 mg / m³ and 5%, respectively. The calibration value.

[0067] The photoelectric signal processor uses the currently acquired concentration of 480 mg / m³ and 96% as bilinear interpolation search conditions. It performs bilinear interpolation between 0.048 rad, 0.052 rad, 0.051 rad, and 0.055 rad corresponding to four adjacent calibration grid nodes to obtain a medium scattering correction coefficient that matches the current state of suspended aerosols in the roadway. .

[0068] The measurement host synchronously starts the coaxial dual-wavelength high-frequency amplitude-modulated laser emission module with the initial drive current. Transmit the main wavelength to each target 650nm, secondary wavelength 808nm and modulation frequency A 15MHz coaxial dual-wavelength high-frequency amplitude-modulated laser beam is used; the photodetector receives the first bottom reflection target. The reflected echo signal, demodulated by the photoelectric signal processor, yields the dominant wavelength echo intensity. The value is 0.03, which is below the effective threshold for light intensity reception. .

[0069] The measuring host then activates the drive current closed-loop adjustment circuit, gradually increasing the drive current in fixed steps of 10mA. When the drive current increases to... At that time, the dominant wavelength echo intensity The subwavelength echo intensity was restored to 0.11. The intensity was restored to 0.55, both of which reached or exceeded the effective threshold for light intensity reception, and the driving current did not exceed the maximum safe driving current of the laser, 200mA.

[0070] The electro-optic conversion slopes of the primary wavelength laser diode and the secondary wavelength laser diode are different. The measurement host has a pre-stored dual-wavelength power ratio compensation table. When the drive current is adjusted step by step, the control unit adjusts the drive gain of the two lasers according to the compensation table to keep the initial output light intensity ratio of the two lasers at the transmitting end constant. The photoelectric signal processor uses the change in the intensity of the two echoes at the receiving end to characterize the medium scattering attenuation in the propagation path.

[0071] After the echo light intensity is restored, the photoelectric signal processor... and Calculate the wavelength light intensity attenuation ratio Combined with dynamically retrieved medium scattering correction coefficients Calculate the phase lag correction amount ,use Correcting the original phase difference of the dominant wavelength The corrected phase shift is obtained. And calculate the measurement origin based on the corrected phase shift. To the first bottom reflective target absolute distance The speed of light in a vacuum used in this study 3×10 8 m / s.

[0072] At the time of measurement The rheological changes in the tunnel roof and walls cause a complex spatial displacement, including translational and angular displacements, on the suspended platform where the measuring machine is located. This is the first steady-state reference target. Second steady-state baseline target and the third steady-state benchmark target The corresponding absolute distance changes accordingly. The photoelectric signal processor takes the initial position of the three steady-state reference targets in the local three-dimensional measurement coordinate system as the reference, inputs the absolute distance between the initial time and the measurement time into the trilateration algorithm with singular value decomposition least squares adjustment, and iteratively solves the three translational degrees of freedom components and three rotational degrees of freedom angular displacement generated by the measurement host relative to the stable rock layer.

[0073] In each iteration, the rotation matrix is ​​updated based on the current angular displacements of the three rotational degrees of freedom. Update the translation vector based on the three translational degrees of freedom components. The residuals between the predicted and measured absolute distances of each steady-state reference target are calculated, and the least-squares solution of the residual equation is obtained through singular value decomposition until the residuals of each distance satisfy the convergence condition, thus obtaining the measurement host's... and Based on this, a fourth-order isomorphic tunnel section rigid body displacement decoupling matrix is ​​constructed. .

[0074] Optoelectronic signal processor Find the inverse to obtain the inverse matrix. Then apply it to the measurement time. The first bottom reflective target obtained The four-dimensional homogeneous original measurement coordinate column vector The true spatial coordinate column vector after the translation and rotation intervention of the suspended platform is obtained. Extract the true normal coordinate values ​​parallel to the base plate normal direction from the true space coordinate column vector. and at the initial time normal coordinate values Deduction The first bottom reflective target was obtained. Net bulge displacement .

[0075] Using the same environmental data acquisition, medium scattering correction coefficient retrieval, drive current adjustment, phase lag correction, and inverse coordinate transformation process, the second bottom-bulging reflection target was obtained. Third bottom reflective target and the fourth bottom reflective target Net bulge displacement at their respective lateral coordinates , and .

[0076] The lateral position coordinates of each bottom-reflecting target As the independent variable, the corresponding net uplift displacement As the dependent variable, natural boundary conditions are set and a cubic spline interpolation function is constructed. The continuous bottom bulge deformation profile of the bottom plate under test was reconstructed. The geometric extrema where the first derivative of the cubic spline interpolation function is zero were solved for each transverse interval. The maximum bottom bulge of the bottom plate at the test section was found to be 0.1865 m, and its transverse coordinates are as follows: m, the measuring host outputs the measurement results of continuous bottom deformation under high dust, high humidity fluctuation conditions and composite spatial displacement conditions of the suspended platform.

[0077] Example 4: This example combines Figures 1 to 3 This paper describes a method for measuring the floor heave deformation in soft rock tunnels, such as... Figure 1 As shown, in step S1, a local measurement coordinate system is established at the section to be measured in the tunnel. Steady-state reference targets are installed on the roof and two sides, and a bottom heave reflection target is installed on the floor. In step S2, a coaxial dual-wavelength high-frequency amplitude-modulated laser beam is emitted to the steady-state reference target and the bottom heave reflection target. The echo signal is collected and demodulated to obtain the original phase difference and light intensity. In step S3, the wavelength light intensity attenuation ratio is determined according to the light intensity ratio. The phase lag correction is calculated according to the medium scattering model to correct the phase difference, and the absolute distance of the target is calculated. In step S4, the translation vector and rotation matrix are solved by the trilateration algorithm based on the absolute distance change of the steady-state reference target to construct the rigid body displacement decoupling matrix. In step S5, the inverse matrix of the rigid body displacement decoupling matrix is ​​used to apply an inverse transformation to the coordinates of the bottom heave reflection target to remove the spatial displacement and calculate the true coordinates and net heave displacement. In step S6, the cubic spline interpolation algorithm is used to fit the net heave displacement to reconstruct the continuous bottom heave deformation profile of the floor of the section to be measured.

[0078] like Figure 2 As shown, after establishing a local measurement coordinate system, the measurement host controls the emission of a coaxial dual-wavelength laser beam. The measurement host then collects and demodulates the echo signal, retrieves the medium scattering correction coefficient, and calculates the absolute distance. Subsequently, a rigid body displacement decoupling matrix is ​​constructed and the net bulge displacement is obtained to reconstruct the continuous bottom bulge deformation profile. After reconstructing the continuous bottom bulge deformation profile, the process returns to the stage of emitting the coaxial dual-wavelength laser beam.

[0079] like Figure 3 As shown, the measurement host integrates a coaxial dual-wavelength high-frequency amplitude-modulated laser emission module, a photodetector, an environmental sensor, and a photoelectric signal processor. The coaxial dual-wavelength high-frequency amplitude-modulated laser emission module emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams to the first, second, and third steady-state reference targets in the stable rock strata, as well as the first, second, third, and fourth bottom bulge reflection targets in the bottom plate test profile. The first, second, and third steady-state reference targets, the first, second, and third bottom bulge reflection targets, and the fourth bottom bulge reflection targets return echo signals to the photodetector. The photodetector and the environmental sensor output signals to the photoelectric signal processor.

[0080] Example 5: Before installing the measuring host on the section to be measured in the soft rock roadway, the scattering characteristics of the suspended medium are first calibrated through an offline pipeline in the laboratory. The calibration range covers the dust mass concentration. 0 to 500 mg / m³, relative humidity The combined operating conditions range from 70% to 98%, with a grid step size of 50 mg / m³ for dust mass concentration and 5% for relative humidity.

[0081] At each calibration grid node, the coaxial transmission dominant wavelength is... 650nm, secondary wavelength A high-frequency amplitude-modulated laser beam of 808nm was used to collect the echo intensity at the main wavelength. and subwavelength echo intensity Calculate the wavelength light intensity attenuation ratio Simultaneously, the phase lag caused by the laser beam propagating in the corresponding aerosol medium is recorded, based on the values ​​of each calibrated grid node. Calculate the medium scattering correction factor with phase hysteresis A calibration curve for roadway aerosols was established using dust mass concentration and relative humidity as independent variables. The corresponding values ​​for each calibration curve are... A two-dimensional medium scattering calibration matrix is ​​constructed, and this matrix is ​​stored in the memory of the measurement host to form a medium scattering calibration database.

[0082] After the measuring unit is installed on the suspended platform, the dust concentration sensor and humidity sensor integrated on the surface of the housing collect data on the cross-section under test in real time. and The photoelectric signal processor uses the current acquired value as the bilinear interpolation retrieval condition to retrieve data from the medium scattering calibration database that matches the current state of suspended aerosols in the roadway. Combined with the wavelength light intensity attenuation ratio Calculate the phase lag correction amount The phase lag correction is used to correct the original phase difference of the main wavelength. .

[0083] When the measuring host is fixed on the suspended platform above the section to be measured and the surrounding rock rheology of the roadway has not yet occurred, the first steady-state reference targets are installed on the stable rock mass of the roof, the stable rock strata of the left sidewall, and the stable rock strata of the right sidewall, respectively. Second steady-state baseline target and the third steady-state benchmark target The measurement host emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams towards three steady-state reference targets, and acquires the measurement origin at the initial moment. to , and The absolute distances of the three steady-state reference targets in the local three-dimensional measurement coordinate system are calculated using a trilateration algorithm. The initial spatial coordinates in the space.

[0084] When a change in the position of the suspended platform is detected due to blasting or mining disturbance at the working face, the measurement host initiates baseline calibration. The photoelectric signal processor acquires the absolute distances of three steady-state reference targets at the current measurement moment and compares them with the absolute distances at the initial moment to obtain the absolute distance changes of each steady-state reference target. Then, the three translational degrees of freedom components and three rotational degrees of freedom angular displacements generated by the measurement host relative to the stable rock strata are solved using a trilateration algorithm to determine the translation vector. With rotation matrix Reconstruct the rigid body displacement decoupling matrix of the fourth-order isomorphic tunnel section. and its inverse matrix .

[0085] In the subsequent measurement of the bottom bulge deformation, Acting on various bulging reflective targets The four-dimensional homogeneous original measurement coordinate column vector The true spatial coordinate column vector of the suspended platform where the stripping measurement host is located is obtained after translation and rotation intervention. Based on the normal coordinate values ​​in the real space coordinate column vector, the net bulge displacement of each bottom bulge reflection target is calculated and used to reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section.

[0086] Example 6: During the reconstruction of the continuous floor heave deformation profile of the soft rock tunnel floor, when the floor rock is locally fractured or the floor heave is accompanied by a small area of ​​spalling, some floor heave reflection targets laid on the floor to be measured may have transient displacement anomalies. In response to this situation, the data processing unit performs data filtering and anomaly removal to avoid local distortion of the cubic spline interpolation results caused by abnormal measuring points.

[0087] The calculated reflection targets on the bottom plate profile are obtained from the bottom plate. Net bulge displacement and its lateral position coordinates Then, the data processing unit extracts all data within the current measurement period. The sequence of heave displacements at each measuring point, for any intermediate measuring point Read the measurements from the adjacent measuring points on its left side respectively. and adjacent measuring points on the right Horizontal position coordinates , and the corresponding net uplift displacement. , The measurement points are calculated by linear interpolation. Expected displacement of the bulge: Subsequently, the measuring points were calculated. The absolute residual between the actual calculated net uplift displacement and the expected uplift displacement: absolute residual value With the preset spatial smoothness threshold When comparing, Greater than At that time, the data processing unit determines the measurement point. The corresponding echo signal is affected by local fragmentation or obstruction, and the measurement point is marked as an invalid anomaly.

[0088] In the subsequent reconstruction of the continuous bottom heave deformation profile, the data processing unit automatically removes invalid outliers and only substitutes the lateral position coordinates and net heave displacement of the remaining valid measuring points into the cubic spline interpolation function with natural boundary conditions. Fitting is performed to avoid abrupt changes in the reconstructed continuous bottom bulge deformation profile caused by abnormal displacement.

[0089] The spatial smoothness threshold of 0.05m is determined by combining the maximum geometric particle size of the rock fragments on the roadway floor and the maximum physical curvature of the continuous rock mass when the distance between adjacent measuring points is 1.0m. When the absolute residual value of the measuring point exceeds this threshold, its displacement exceeds the physical range of the deformation of the continuous rock mass. It can be determined as random noise caused by fragment falling or local obstruction, and the measuring point is removed from the reconstructed data of the continuous floor deformation profile.

[0090] The above description is only a few preferred embodiments of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present invention is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, technical solutions formed by replacing the above-mentioned features with the technical features with similar functions disclosed in the embodiments of the present invention.

Claims

1. A method for measuring the floor heave deformation in soft rock tunnels, characterized in that, Includes the following steps: Step S1: Establish a local measurement coordinate system on the section to be measured in the soft rock tunnel. Install three non-collinear steady-state reference targets on the top plate and the stable rock mass surfaces on both sides of the section to be measured, and install multiple bottom heave reflection targets on the bottom plate section to be measured. Step S2: The measurement host suspended above the cross section to be measured emits coaxial dual-wavelength high-frequency amplitude-modulated laser beams to each steady-state reference target and each bottom reflection target, collects echo signals and demodulates to obtain the original phase difference of the main wavelength, the echo intensity of the main wavelength and the echo intensity of the secondary wavelength. Step S3: Determine the wavelength intensity attenuation ratio based on the ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; calculate the phase lag correction amount based on the medium scattering model including the medium scattering correction coefficient to correct the original phase difference of the main wavelength; and calculate the absolute distance from the measuring host to each target. Step S4: Based on the absolute distance changes of each steady-state reference target at different measurement times, the translation vector and rotation matrix of the measuring host are solved by the trilateration algorithm to construct the rigid body displacement decoupling matrix of the section to be measured. Step S5: Apply an inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement moment using the inverse matrix of the rigid body displacement decoupling matrix, strip away the spatial displacement of the measurement host, and calculate the true spatial coordinates and the net bulge displacement along the normal of the bottom plate. Step S6: Use cubic spline interpolation algorithm to fit the net bulge displacement of each bottom bulge reflection target, and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section.

2. The method for measuring the floor heave deformation in soft rock tunnels according to claim 1, characterized in that, In step S2, when emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, the following sub-steps are included: Step S21, emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam with a main wavelength of 650nm, a secondary wavelength of 808nm, and a modulation frequency of 15MHz. The main wavelength and the secondary wavelength are converged by a coaxial collimating optical system and then directed in parallel towards each steady-state reference target and each bottom-reflection target; Step S22, receiving the echo signal reflected by the target through a photodetector, and extracting the original phase difference of the main wavelength, the echo intensity of the main wavelength, and the echo intensity of the secondary wavelength through a narrowband frequency-selective amplification circuit and a mixer demodulation circuit.

3. The method for measuring the floor heave deformation in soft rock tunnels according to claim 1, characterized in that, In step S3, when calculating the phase lag correction based on the medium scattering model including the medium scattering correction coefficient, the following sub-steps are included: Step S31, calculate the wavelength intensity attenuation ratio. The ratio of the main wavelength echo intensity to the secondary wavelength echo intensity; Step S32, calculate the phase lag correction caused by scattering from the suspended medium according to the following formula. : ,in, This is the phase lag correction amount. The wavelength-intensity attenuation ratio. To obtain the determined medium scattering correction coefficient based on the roadway aerosol calibration curve; step S33, subtract the phase lag correction amount using the original phase difference of the dominant wavelength. The corrected phase shift is obtained, and the absolute distance is calculated based on the corrected phase shift.

4. The method for measuring the floor heave deformation in soft rock tunnels according to claim 3, characterized in that, In step S33, when calculating the absolute distance from the measuring host to each target: the corrected phase shift is multiplied by the speed of light in vacuum, and the resulting product is divided by the product of four times pi and the laser modulation frequency to calculate the absolute distance from the measuring origin to each steady-state reference target and each bottom-reflection target; wherein, the speed of light in vacuum used is 3 × 10⁻⁶. 8 m / s, laser modulation frequency is 15MHz.

5. A method for measuring floor heave deformation in soft rock tunnels according to claim 1, characterized in that, In step S1, three steady-state reference targets are installed at the top centerline of the section to be measured, the left side stable rock layer, and the right side stable rock layer, respectively. The three steady-state reference targets form a non-collinear triangular ranging reference surface in space. In step S4, the absolute distances between the three steady-state reference targets at the initial time and the current measurement time are used to solve the three translational degrees of freedom components and three rotational degrees of freedom angular displacements generated by the measuring host relative to the stable rock strata through the trilateration algorithm, thereby constructing a fourth-order isomorphic tunnel section rigid body displacement decoupling matrix containing translation vectors and rotation matrices.

6. A method for measuring the floor heave deformation in soft rock tunnels according to claim 5, characterized in that, In step S5, when applying the inverse transformation to the original measurement coordinates of each bottom bulge reflection target at the current measurement time, the following sub-steps are included: Step S51, obtain the inverse matrix of the rigid body displacement decoupling matrix of the tunnel section, and then multiply the inverse matrix with the four-dimensional homogeneous original measurement coordinate column vector of each bottom bulge reflection target to derive the real spatial coordinate column vector after the rigid body translation and rotation intervention of the stripping measurement host suspension platform; Step S52, take the coordinate axis parallel to the normal direction of the bottom plate as the deformation extraction axis, subtract the real normal coordinate value calculated at the current measurement time from the normal coordinate value of the bottom bulge reflection target at the initial time, and obtain the net bulge displacement of each bottom bulge reflection target.

7. The method for measuring the floor heave deformation in soft rock tunnels according to claim 1, characterized in that, In step S6, when using the cubic spline interpolation algorithm to fit and reconstruct the continuous bottom bulge deformation profile of the bottom plate of the test section, the following sub-steps are included: Step S61, taking the lateral position coordinates of each bottom bulge reflection target as the independent variable and the corresponding net bulge displacement as the dependent variable, a cubic polynomial interpolation function is established within the lateral interval formed by adjacent bottom bulge reflection targets; Step S62, setting natural boundary conditions to solve the coefficients of each order of the cubic polynomial interpolation function, fitting the continuous bottom bulge deformation curve spanning the entire bottom plate test section, and solving for the geometric extreme points where the first derivative of the continuous bottom bulge deformation curve is zero, outputting the maximum bottom bulge bulge amount of the bottom plate of the test section and the lateral position coordinates of the occurrence of the maximum bottom bulge bulge amount.

8. A method for measuring the floor heave deformation in soft rock tunnels according to claim 3, characterized in that, Medium scattering correction factor The retrieval and determination method is as follows: a media scattering calibration database corresponding to different dust mass concentrations and relative humidityes is pre-stored inside the measuring host; while emitting a coaxial dual-wavelength high-frequency amplitude-modulated laser beam, dust mass concentration data and relative humidity data of the current cross-section to be measured are collected by an environmental sensor integrated on the surface of the measuring host, and bilinear interpolation is performed in the media scattering calibration database to dynamically retrieve the media scattering correction coefficient that matches the current state of suspended aerosols in the roadway. .

9. A method for measuring the floor heave deformation in soft rock tunnels according to claim 1, characterized in that, When acquiring echo signals in step S2, if the intensity of the main wavelength echo or the intensity of the secondary wavelength echo obtained by demodulation is lower than the preset effective threshold for light intensity reception, it is determined that the current optical path is interfered with by a sudden high concentration of dust. At this time, the measuring host automatically increases the laser emission driving current to increase the output optical power, and when the light intensity recovers to above the effective threshold for light intensity reception, the phase lag correction and absolute distance calculation in step S3 are started.

10. A method for measuring the floor heave deformation in soft rock tunnels according to claim 7, characterized in that, After reconstructing the continuous floor heave deformation profile of the test section floor plate in step S6, a floor plate instability early warning is performed: the calculated maximum floor heave amount is compared with the preset allowable deformation critical threshold of the roadway floor plate. If the maximum floor heave amount exceeds the allowable deformation critical threshold, or the maximum value of the local curvature of the continuous floor heave deformation curve exceeds the preset floor plate bending stress concentration threshold, a floor heave early warning signal indicating that the test section floor plate has an instability risk and a corresponding floor plate bottom anti-arch support location suggestion are generated and output.

Images