CN-122015687-A - Device and method for monitoring tunnel deformation in existing subway section caused by pipe jacking construction

CN122015687ACN 122015687 ACN122015687 ACN 122015687ACN-122015687-A

Abstract

The invention relates to the technical field of tunnel monitoring, and discloses a device and a method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction, wherein the device comprises optical fibers which are laid on the cambered surface of the inner wall of a tunnel in a serpentine wave shape, the optical fibers are spread towards two sides by taking the top of the tunnel as the center, the side wall of the tunnel is bent back and forth between the left side wall and the right side wall while extending longitudinally along the tunnel, so that the wave crest part is positioned on one side of the tunnel and the wave trough part is positioned on the other side of the tunnel, and the wave crest part and the wave trough part are highly flush in the cross section of the tunnel. The optical fiber is laid on the cambered surface of the inner wall of the tunnel in a serpentine wavy manner, radial deformation of the section of the tunnel is converted into axial strain of the optical fiber by utilizing the wavy geometry, and meanwhile, the optical fiber extends longitudinally, so that longitudinal uneven settlement can be perceived.

Inventors

LU HE
SU SHIYUAN
LI HAO
XU XIANMING
WANG SHENGTAO
YANG QING

Assignees

安徽建工公路桥梁建设集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260403

Claims (8)

1. The utility model provides a push pipe construction causes current subway interval tunnel to warp monitoring devices which characterized in that includes following structure: the optical fiber is laid on the cambered surface of the inner wall of the tunnel in a serpentine wavy manner, spreads towards two sides by taking the top of the tunnel as the center, and is bent back and forth between the left side wall and the right side wall while extending longitudinally along the tunnel, so that the peak part is positioned on one side wall of the tunnel and the trough part is positioned on the other side wall of the tunnel, and the peak part and the trough part are highly flush in the cross section of the tunnel; the fixing parts are arranged on serpentine wavy lines which are equidistantly distributed on the optical fibers, and are rigidly connected with the inner wall of the tunnel through screws so that the optical fibers are attached to the inner wall of the tunnel, the optical fibers are completely restrained at the fixing parts, and the optical fibers are arc-shaped between the two fixing parts, so that the stress of the optical fibers caused by temperature difference is reduced; The distributed optical fiber sensing equipment is in optical coupling connection with one end or two ends of the optical fiber; And the data processing unit is electrically connected with the distributed optical fiber sensing equipment and is used for executing tunnel deformation monitoring.
2. The method for monitoring deformation of the tunnel in the existing subway section caused by pipe jacking construction is characterized by comprising the following specific operations of: The method comprises the steps that S1, strain distribution data of optical fibers along the line are obtained through distributed optical fiber sensing equipment, the optical fibers are laid on the cambered surface of the inner wall of a tunnel in a serpentine wavy mode, the optical fibers are spread towards two sides by taking the top of the tunnel as the center, and are bent back and forth between the left side wall and the right side wall while extending longitudinally along the tunnel, so that the peak parts are positioned on one side wall of the tunnel and the trough parts are positioned on the other side wall of the tunnel, the peak parts and the trough parts are highly leveled in the cross section of the tunnel, and the strain distribution data comprise strain values corresponding to length coordinates of all the optical fibers; S2, dividing an optical fiber into a plurality of longitudinal sections according to geometric parameters of the serpentine wavy pavement, establishing a mapping relation between the length coordinates of the optical fiber in each longitudinal section and the circumferential angles of the inner walls of the tunnel, and converting the strain distribution data into a two-dimensional strain field, wherein the two-dimensional strain field takes the longitudinal coordinates of the tunnel and the circumferential angles as independent variables, and the value range of the circumferential angles is an angle interval extending from the top of the tunnel to the left side wall and the right side wall; s3, for each longitudinal section, calculating the circumferential arc length variation corresponding to the section according to the strain distribution of the optical fiber along the section; s4, inverting the radial deformation characteristics of the tunnel section in the longitudinal section according to the circumferential arc length variation; And S5, judging that the longitudinal section has deformation risk and outputting the longitudinal mileage range of the longitudinal section when the radial deformation characteristic of any longitudinal section exceeds a preset threshold, or judging that the two longitudinal sections corresponding to the adjacent areas have deformation risk and outputting the longitudinal mileage ranges of the two longitudinal sections when the strain difference value in the two-dimensional strain field exceeds an adjacent area of the preset threshold.
3. The method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction according to claim 2, wherein the mapping relation in the step S2 is characterized in that the corresponding relation between the optical fiber length coordinate and the tunnel longitudinal coordinate and the circumferential angle is established according to the wave period, the wave amplitude and the starting point coordinate of the optical fiber serpentine wave pavement, wherein the circumferential angle takes the tunnel top as 0 degree, the side wall on one side as a positive direction, and the side wall on the other side as a negative direction.
4. The method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction according to claim 2, wherein the calculation process of the circumferential arc length change in the step S3 is as follows: For any longitudinal section, let the number of reciprocations of the optical fiber in the section in the circumferential direction be k, the initial length coordinate of the optical fiber in the section be l_start, the end length coordinate be l_end, the strain distribution of the optical fiber along the section be epsilon (L), the circumferential arc length change delta C of the section be: Or for discrete sampled strain data, take the form of summation: Where m is the number of segments of optical fiber within the segment, ε_j is the average strain value on the j-th fiber segment, ΔL_j is the length of the segment.
5. The method for monitoring deformation of tunnel in existing subway section caused by pipe jacking construction according to claim 2, wherein the radial deformation characteristics in step S4 include at least one of a vault settlement amount, a sidewall convergence amount and a section ovalization degree, and are calculated by: for the dome settlement amount δ_crown, it is calculated from the strain value ε_crown of the optical fiber segment within a preset range around 0 ° in the section and the tunnel design radius R: ; For the sidewall convergence delta_wall, calculating according to the strain values epsilon_left and epsilon_right of the corresponding optical fiber segments of the left and right sidewalls in the section and the tunnel design radius R, ; The degree η of the cross-section ovalization is calculated from the difference between the dome settlement amount and the sidewall convergence amount, and is as follows: 。
6. The method for monitoring tunnel deformation in an existing subway section caused by pipe jacking construction according to claim 2, wherein the adjacent areas where the strain difference exceeds the preset threshold in step S5 are identified by: Dividing the two-dimensional strain field into a plurality of continuous grid cells along the longitudinal direction, wherein each grid cell corresponds to one circumferential angle range in one longitudinal section, and calculating strain difference delta epsilon_i between grid cells in the same circumferential angle range which are adjacent along the longitudinal direction: ; The method comprises the steps of determining the longitudinal sections of a grid cell, wherein epsilon_i is an average strain value in the circumferential angle range in the ith longitudinal section, marking the ith longitudinal section and the (i+1) th longitudinal section as strain abrupt change areas when the strain difference delta epsilon_i exceeds a preset threshold value, and determining that uneven settlement exists in the continuous longitudinal sections when the strain difference of two or more continuous longitudinal adjacent grid cells exceeds the preset threshold value.
7. The method for monitoring tunnel deformation in an existing subway section caused by pipe jacking construction according to claim 2, wherein outputting the longitudinal mileage range of the longitudinal section in step S5 comprises: The method comprises the steps of converting a section number of a longitudinal section into a longitudinal mileage range, marking the longitudinal mileage range on a three-dimensional model or a two-dimensional expansion chart of a tunnel in a visual mode, marking deformation risk levels in the longitudinal mileage range, dividing the deformation risk levels according to the ratio of radial deformation characteristics to a preset threshold value, and outputting deformation type identification of the longitudinal section, wherein the deformation type identification comprises at least one of vault settlement, side wall convergence and cross section ovalization.
8. The method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction according to claim 2 is characterized by further comprising the step S6 of carrying out differential processing on radial deformation characteristics of the same longitudinal section obtained at different time points to obtain the change rate of the radial deformation characteristics of the longitudinal section along with time, and sending out an early warning signal when the change rate exceeds a preset rate threshold.

Description

Device and method for monitoring tunnel deformation in existing subway section caused by pipe jacking construction Technical Field The invention relates to the technical field of tunnel monitoring, in particular to a device and a method for monitoring tunnel deformation in an existing subway section caused by pipe jacking construction. Background The pipe jacking construction is widely applied to urban underground space development as a non-excavation pipeline laying technology. However, in the pipe jacking construction process, stress redistribution and displacement of surrounding soil bodies can be caused due to factors such as soil body excavation, jacking thrust, grouting pressure, stratum loss and the like, so that adverse effects are generated on adjacent existing subway section tunnels. These effects are mainly manifested by deformation of subway tunnels such as uneven settlement along the longitudinal direction, vault settlement of transverse sections, sidewall convergence, ovalization of sections, etc. If the deformation exceeds the allowable range, the tunnel lining is possibly cracked, the joint is leaked, the ballast bed is separated, even the structure is unstable, and the subway operation safety is seriously threatened. In the pipe jacking construction period, the deformation monitoring of tunnels adjacent to the existing subway section in real time, continuously and high-precision is an important measure for guaranteeing the safe operation of subways. In existing fiber monitoring schemes, the optical fibers are typically laid down on the inner wall (e.g., dome, sidewall, or inverted arch) longitudinally along the tunnel in a straight line and fixed at fixed points by fasteners (e.g., clips, anchors). However, this straight line laying method has corresponding technical problems. The axial direction of the optical fiber laid in a straight line is completely consistent with the longitudinal direction of the tunnel. Optical fiber sensing can only sense strain in its axial direction. Deformation of the subway tunnel caused by pipe jacking construction is often multidimensional, namely uneven settlement along the longitudinal direction, vault settlement of the cross section and side wall convergence are caused. For radial deformation of the profile (e.g., dome subsidence, sidewall convergence), the straight fiber experiences little axial strain (only slight bending occurs, bending induced axial strain is negligible). Therefore, even if the tunnel section has significantly converged or ovalized, the straight fiber may still output a near zero strain signal, resulting in a false negative of the safety hazard. In other words, the straight line laying can only monitor longitudinal deformation, and the real influence of pipe jacking construction on the section of the tunnel cannot be comprehensively reflected. Although the prior art adopts fixed point fixation (instead of full-line gluing) to allow the optical fiber to slightly slide between the fixed points, the temperature stress is released to a certain extent, and due to the simple straight optical fiber path and the large distance between the fixed points, under the possible environmental temperature fluctuation during pipe jacking construction and the temperature difference change in a tunnel, the difference of the thermal expansion coefficients of the optical fiber and the lining can still cause accumulated thermal stress, so that the optical fiber generates stress concentration or relaxation at the fixed points, and the long-term stability and reliability of the monitoring data are affected. Therefore, the invention provides a device and a method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a device and a method for monitoring tunnel deformation in the existing subway section caused by pipe jacking construction, solves the problem of temperature stress influence, detects tunnel deformation through axial strain, and improves monitoring results. The invention provides a monitoring device for deformation of an existing subway section tunnel caused by pipe jacking construction, which comprises the following structures: the optical fiber is laid on the cambered surface of the inner wall of the tunnel in a serpentine wavy manner, spreads towards two sides by taking the top of the tunnel as the center, and is bent back and forth between the left side wall and the right side wall while extending longitudinally along the tunnel, so that the peak part is positioned on one side wall of the tunnel and the trough part is positioned on the other side wall of the tunnel, and the peak part and the trough part are highly flush in the cross section of the tunnel; the fixing parts are arranged on serpentine wavy lines which are equidistantly distributed on the optical fibers, and are rigidly connected with the inner wall