A method for fitting a center line of fine adjustment of a tunnel lining back plane control point

Abstract

The present application relates to a kind of tunnel lining rear plane control point fine adjustment of tunnel lining plane control point coordinate, lining section measured data and tunnel line design parameter are obtained in the middle line fitting method of technical field of tunnel engineering survey and line design, comprising the following steps: S1,;S2, lining measured section is compared with clearance profile generated with original control point as benchmark middle line, calculates overall deviation;S3, determine the adjustment amount of each plane control point coordinate, verify the accuracy of adjusted control network;Adjustment amount minimizes the weighted sum of square of radial deviation and horizontal deviation of each section as target and iteratively solved, S4, re-fitting tunnel middle line, compare fitting middle line with lining measured section, not meet the requirements, return S2, re-execute deviation tracing and subsequent steps, until meet the conditions;The method does not change design parameter, also does not dig out lining, only fine adjustment plane control point, and the middle line fitting of section size and limit is realized by closed loop iteration.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering surveying and route design technology, and in particular to a centerline fitting method for fine-tuning of plane control points after tunnel lining. Background Technology

[0002] As is well known, whether the over-excavation and under-excavation of the tunnel lining section and the construction clearance meet the standards are directly related to operational safety and structural durability. After construction, factors such as surrounding rock deformation, construction process errors, and measurement errors often lead to local under-excavation (encroachment on the construction clearance) or over-excavation (the clearance is too large and the lining is too thick). In actual engineering, the error of the plane control measurement inside the tunnel is the main reason for the overall and regularity of the cross-sectional deviation.

[0003] To address the aforementioned issues, two main approaches are currently employed: one is to remove the lining from the under-excavated areas and pour concrete to fill the over-excavated areas. This method is costly, time-consuming, and prone to damaging the integrity of the lining, and the clearance restoration accuracy is difficult to control. The other approach is to modify the original design parameters (such as curve radius, straight line direction, and transition curve length) and refit the centerline to accommodate the completed lining. However, this deviates from the original design intent, affects the smooth connection of tunnel entrances and exits and operational safety, and lacks a standardized closed-loop process.

[0004] Therefore, there is an urgent need for a method that can preserve the original design parameters, avoid damaging the completed lining, and simultaneously solve the problems of over-excavation, under-excavation, and clearance with high precision. Summary of the Invention

[0005] To overcome the shortcomings of the prior art and solve the existing technical problems, this invention discloses a centerline fitting method for fine-tuning the plane control points after tunnel lining. This method does not change the line design parameters or remove the lining, but only fine-tunes the plane control points, so that the refitted tunnel centerline can control the over-excavation and under-excavation of the lining section and the clearance deviation within the allowable range of the specifications.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A centerline fitting method for fine-tuning of plane control points after tunnel lining includes the following steps: S1, acquiring the coordinates of plane control points inside the tunnel, measured data of the lining cross-section, and fixed tunnel alignment design parameters; S2, comparing the measured cross-section of the lining with the theoretical clearance profile generated by fitting the centerline according to the alignment design parameters based on the original control points, calculating the radial and horizontal deviations of each cross-section, and distinguishing the overall deviations belonging to the plane control system; S3, within the allowable tolerance range, determining the adjustment amount of the coordinates of each plane control point and correcting its coordinates, and verifying the accuracy of the adjusted control network; The adjustment amount is iteratively solved with the optimization objective of minimizing the weighted sum of squares of radial and horizontal deviations of each section. The weights of radial and horizontal deviations are set based on the maximum allowable over-excavation value and the allowable offset of the construction clearance, respectively. S4: Using the adjusted and verified control points as the benchmark, the tunnel plane centerline is refitted using the original route design parameters. The fitted centerline is compared with the measured lining section again. If the over-excavation, under-excavation, and clearance indicators do not meet the requirements, return to S2. The deviation of the fitted section is used as the input data to re-execute the deviation tracing and subsequent steps until all sections meet the compliance conditions.

[0008] Furthermore, the weight of the radial deviation is taken as 1 / (ΔR). max ) 2 , where ΔR max The absolute value of the maximum allowable over-excavation is specified; the weight of the horizontal deviation is taken as 1 / (ΔH). max ) 2 , where ΔH max This is the absolute value of the allowable offset for the building clearance.

[0009] Furthermore, the iterative optimization is solved using a sequential quadratic programming method or an interior point method, and the calculation of radial and horizontal deviations in each iteration is based on the theoretical net clearance profile generated by the latest centerline after the coordinate refit of this round of adjustment.

[0010] Furthermore, the accuracy verification of the adjusted control network in S3 includes: the relative closure error of the traverse and the positional error of the weakest point meet the relevant requirements of the current tunnel construction specifications, and the absolute value of the difference between the plane coordinates measured by the adjusted control network inside the tunnel and the control network outside the tunnel does not exceed 25mm for railway tunnels and does not exceed 20mm for highway tunnels; if the accuracy does not meet the requirements, the constraint weights or data weights in the optimization model are adjusted and the solution is resolved.

[0011] Furthermore, the allowable tolerance in the specification is determined to be ±20mm to ±25mm based on the provisions for the positional error of control points in the traverse survey specifications for highway or railway tunnels, with ±25mm for railway tunnels and ±20mm for highway tunnels.

[0012] Furthermore, the measured data of the lining cross-section were collected by a laser profiler in conjunction with a total station with a time interval of no less than 2 seconds. A cross-section was collected every 10m on straight sections and every 5m on curved sections.

[0013] Furthermore, in S2, the criteria for determining the overall deviation are: the standard deviation of the deviation vector direction angle of at least 5 consecutive cross-sections is less than 15 degrees, and the coefficient of variation of the vector magnitude is less than 10%; otherwise, it is determined to be a deviation caused by local factors and will not be adjusted. The threshold of the standard deviation of the deviation vector direction angle being less than 15 degrees is derived from the error propagation law combined with a signal-to-noise ratio of not less than 4, and the threshold of the coefficient of variation of the vector magnitude being less than 10% is derived from the measured statistical analysis of multiple tunnel projects.

[0014] Furthermore, in S1, the fixed line design parameters include the radius of the planar curve, the length of the transition curve, and the geometric angle relationship between each line element; while the coordinates of the center of the circular curve are recalculated and determined based on the fixed geometric parameters and the coordinates of the current control point during each centerline fitting.

[0015] Furthermore, in S4, the compliance conditions are: the radial under-excavation value of all cross sections is not greater than 0, the over-excavation value is not greater than +50mm, the building clearance does not encroach on the clearance and the clearance margin meets the original design requirements.

[0016] Furthermore, the method also includes the step of periodically reviewing and protecting the adjusted plane control points.

[0017] By employing the technical solution described above, the present invention has the following beneficial effects:

[0018] The centerline fitting method for fine-tuning the plane control points after tunnel lining disclosed in this invention does not require the removal or re-laying of the completed lining, avoiding risks such as structural damage, poor bonding between new and old concrete, and damage to the waterproof layer. Furthermore, it does not modify the route design parameters; it only adjusts the coordinates of the control points to make the fitted centerline "accommodate" the existing lining, ensuring smooth connection between tunnel entrances and exits and avoiding operational safety assessments and design changes required for rerouting. More importantly, through deviation statistical tracing, it can accurately identify systemic errors in the plane control network. Through weighted iterative optimization under limit constraints, it can fully utilize the measurement margin allowed by the specifications to solve for the optimal adjustment amount. Through a closed-loop verification mechanism, it ensures that over-excavation, under-excavation, and clearance issues are completely resolved. The method is rigorous and highly reliable. Compared to removal and re-casting or rerouting, this method has a shorter construction period, lower cost, and stronger engineering practicality. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be described with reference to the accompanying drawings in the embodiments of the present invention.

[0021] Combined with appendix Figure 1 The centerline fitting method for fine-tuning the plane control points after tunnel lining includes the following steps:

[0022] First, baseline data is compiled to obtain the coordinates of the plane control points inside the tunnel, the measured data of the tunnel lining cross-section, and the route design parameters. The plane control points are derived from the traverse or CPII control network inside the tunnel and have undergone closure error adjustment and accuracy evaluation. The measured cross-section data are collected using a laser profiler in conjunction with a total station with a time accuracy of no less than 2 seconds. A cross-section is collected every 10m on straight sections and every 5m on curved sections. Among the route design parameters, parameters characterizing the inherent geometric characteristics of the route, such as the radius of the plane curve, the length of the transition curve, and the turning angle between the straight line and the circular curve, remain fixed throughout the process and cannot be adjusted. However, absolute position parameters, such as the coordinates of the center of the circular curve, are recalculated and determined based on the fixed geometric parameters and the coordinates of the current control points during each centerline fitting. Their values ​​are allowed to shift or rotate slightly as the control points are finely adjusted.

[0023] Then, deviation detection and source tracing are carried out. Using the original plane control points as a reference, the theoretical centerline is fitted using the original design parameters. Using this centerline as a reference, the theoretical clearance profile is generated according to the tunnel design cross-sectional dimensions. Each measured cross-section is compared with the theoretical clearance profile to obtain the radial deviation to reflect over-excavation and under-excavation, and the horizontal deviation to reflect the clearance status. The vector characteristics of these deviations on adjacent cross-sections are statistically analyzed: when the standard deviation of the deviation vector direction angle of no less than 5 consecutive cross-sections is less than 15 degrees, and the coefficient of variation of the vector modulus is less than 10%, it is determined to be a systematic deviation of the plane control network; otherwise, it is determined to be a local deviation caused by factors such as surrounding rock or construction technology, and is not included in the adjustment.

[0024] After confirming the existence of deviations in the plane control system, the process proceeds to the limit adjustment stage. The adjustment limit is determined according to the current highway or railway construction specifications, based on the tunnel type and the provisions regarding the weakest point's positional error in the tunnel's plane control network. For railway tunnels, the limit is ±25mm, and for highway tunnels, it is ±20mm. Using the coordinate adjustments ΔXi and ΔYi of all control points as unknowns, and under the constraints of |ΔXi|≤ limit and |ΔYi|≤ limit, the solution is sought that minimizes the weighted sum of the squares of the radial and horizontal deviations of the measuring points at each cross-section. The radial deviation weight wr is taken as 1 / (ΔR). max ) 2 ΔR max The absolute value of the maximum allowable over-excavation is specified; the horizontal deviation weight wh is taken as 1 / (ΔH). max ) 2 ΔH max The absolute value of the allowable offset for the building clearance; the optimization problem is constructed as a mathematical programming model:

[0025]

[0026] Among them, wr and wh are weighting factors used to balance the contributions of radial deviation and horizontal deviation to the target value;

[0027] ΔR i It is the radial deviation of the centerline of the i-th section after the control points are adjusted and refitted.

[0028] ΔH i It is the horizontal deviation of the midline of the i-th section after adjusting the control points and refitting it.

[0029] For any set of adjustment values ​​(ΔX, ΔY), first update the coordinates of each control point to (Xi+ΔXi, Yi+ΔYi); then, using the updated control points as a reference, recalculate the coordinates of the center of the circular curve according to the original line design parameters (fixed radius, transition curve length, etc.), and then fit the centerline of the entire line; finally, calculate the normal distance from each measured section profile point to the new centerline as the radial deviation ΔRi, and calculate the lateral distance from the section center point to the new centerline as the horizontal deviation ΔHi;

[0030] Constraints: ΔXj≤L, ΔYj≤L (j=1, 2, 3...n);

[0031] These constraints ensure that the coordinate adjustment of each control point is within the specified allowable range, where L is a given constant representing the maximum allowable adjustment range;

[0032] The solution is obtained by iteratively solving the problem using either Sequential Quadratic Programming (SQP) or the interior point method until the convergence condition is met.

[0033] After the adjustment is completed, the internal and external accuracy of the new control network must be verified: the internal accuracy requires that the relative closure error of the traverse and the mean square error of the weakest point meet the relevant clauses in the current tunnel construction technical specifications; the external accuracy requires that the absolute value of the difference between the plane coordinates measured by the control network inside the tunnel and the control network outside the tunnel does not exceed 25mm for railway tunnels and 20mm for highway tunnels; if the accuracy is not met, the constraint weights or data weights in the optimization model should be adjusted and the solution should be resolved.

[0034] After the accuracy verification is passed, the centerline of the entire line is refitted strictly using the original design parameters, with the adjusted plane control points as the benchmark. The azimuth equation is used for straight sections, and the standard equation of the center coordinates is used for circular curve sections. That is, the center coordinates are calculated from the current control points and the fixed radius. The original design transition curve parameter equation is used for transition curve sections. The theoretical clearance profile is generated by using the fitted centerline and compared with the measured cross-section. The acceptance criteria are: the radial under-excavation value of all cross-sections is not greater than 0, the over-excavation value is not greater than +50mm, there is no encroachment on the building clearance, and the clearance margin meets the original design requirements. If individual cross-sections do not meet the above criteria after one fitting, the deviation detection and source judgment are re-performed, and then the process is continued. This cycle is repeated until all cross-sections meet the standards. Actual engineering statistics show that convergence is generally achieved after 2 to 3 global cycles.

[0035] Example 1: Class I highway tunnel: straight line + circular curve;

[0036] A two-way four-lane Class I highway tunnel, 1200m long, is a straight section followed by a circular curve with a radius of R=500m. After the lining was completed, an inspection revealed that the left side of the tunnel was under-excavated, with the clearance encroaching. The horizontal deviation of seven consecutive cross-sections ranged from -30mm to -60mm, and the direction was consistently to the left. Statistical analysis showed that the standard deviation of the deviation vector direction angle was 8 degrees and the coefficient of variation of the modulus was 7%, which met the criteria for determining the plane control deviation.

[0037] Ten horizontal control points were set up inside the tunnel. Based on highway specifications, the tolerance was adjusted to ±20mm. A weighted sum of squares minimization model was constructed, with ΔXi and ΔYi at each point as the reference values. As variables, with constraints |ΔXi|≤20mm and |ΔYi|≤20mm, convergence occurred after 3 iterations. ΔX at each control point was between +8mm and +15mm. Adjusting to the right, ΔY was between -2mm and +3mm. After adjustment, the weakest point of the control network had a mean square error of ±18mm, and the relative closure error of the traverse was 1 / 85000, meeting the requirements of highway tunnel specifications. The maximum absolute value of the coordinate difference with the external control network was 12mm, within the ±25mm limit. Using the adjusted control point coordinates, the centerline was refitted according to the original design parameters to generate the theoretical clearance profile, which was then compared with the measured cross-section: the maximum radial under-excavation was eliminated, the maximum over-excavation was +32mm, not exceeding +50mm, the building clearance was not encroached upon, and the maximum horizontal deviation was ±22mm. A single fitting was sufficient to meet the standards. The entire remediation process took 3 days, saving approximately 800,000 yuan in rectification costs.

[0038] Example 2: Railway Tunnel: Straight Line + Circular Curve + Transition Curve;

[0039] A single-track railway tunnel, 1800m long, has a straight section, a circular curve section with a radius of R=800m, and a transition curve section of 100m in length. After the lining was completed, it was found that the right-side clearance was generally 40mm-70mm too large, with local over-excavation of 30mm-50mm. The standard deviation of the deviation vector direction angle of 8 consecutive cross-sections was 11 degrees, and the coefficient of variation of the modulus length was 9%, which was determined to be a plane control deviation.

[0040] Fifteen control points were set up inside the tunnel, and the tolerance was adjusted to ±25mm according to railway specifications. The initial optimization solution yielded ΔX of approximately -10mm to -18mm. After adjustment to the left, |ΔY| ≤ 5mm. The mean square error of the weakest point after adjustment was ±22mm, the traverse closure error was 1 / 90000, and the maximum absolute value of the difference between the coordinates measured outside the tunnel and the coordinates outside the tunnel was 18mm, all within ±25mm, which is acceptable. After the first refit, the maximum radial overcut was reduced to +35mm, which is within the allowable range, but the left clearance margin was only 15mm, which is slightly insufficient. Therefore, the weight of the horizontal deviation was increased, and the deviation tracing, adjustment, and fitting were re-executed. The second calculation yielded ΔX adjusted to -15mm to -22mm, with an absolute value not exceeding 25mm. After refitting, the maximum radial overcut was further reduced to +28mm, and the left clearance margin was increased to over 35mm, with no encroachment, fully meeting the design requirements. This embodiment saved approximately 1 million yuan in costs and shortened the construction period by 18 days.

[0041] Example 3: Complex alignment highway tunnel: straight line + same-direction circular curve + opposite-direction circular curve + transition curve;

[0042] A six-lane, two-way highway tunnel, 2100m long, consists of a straight section, a circular curve in the same direction with a radius R=1200m, a circular curve in the opposite direction with a radius R=900m, and transition curves of 150m each at both ends. After lining, inspection revealed that the straight section and the circular curve in the same direction in the first half of the tunnel exhibited a uniform rightward shift, with a horizontal deviation of +25mm to +65mm. In the second half, the direction of the reverse circular curve gradually changed, but the standard deviation of the deviation vector direction angle across 12 consecutive sections was only 10 degrees, and the coefficient of variation was 8%, statistically consistent with the deviation criteria of the plane control network system. Eighteen plane control points were established inside the tunnel, with an adjustment limit of ±20mm according to highway specifications. After four iterations of initial optimization, convergence was achieved. The adjustment range of ΔX for each control point was -5mm to -18mm, and ΔY was between -3mm and +4mm. The accuracy of both the internal and external control networks was satisfactory, and the difference between the coordinates measured outside the tunnel and the external coordinates was minimal. The maximum deviation was 19mm, less than the 20mm limit. After refitting the centerline with the adjusted control points, the horizontal deviation in the first half was basically eliminated, with a maximum over-excavation of +38mm. However, the clearance margin of a section at the end of the reverse circular curve was only 12mm, lower than the original design requirement of 20mm. Therefore, the adjusted control point was used as the new benchmark, and the deviation source tracing step was returned. After confirming that the system deviation criterion was still met, the horizontal deviation weight was fine-tuned according to a stricter internal control value during the second optimization. After solving again, the control point ΔX was further fine-tuned to -8mm to -19mm. After refitting again, the clearance margin of this section increased to 28mm, the maximum radial over-excavation of all sections was +31mm, the under-excavation value was 0, the building clearance was not encroached upon, and the standard was fully met. The entire treatment process took only 5 days, with a total cost of about 90,000 yuan, saving about 1.5 million yuan in project costs compared to the excavation and recasting scheme, and shortening the construction period by 20 days.

[0043] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the above embodiments should be regarded as exemplary and non-limiting in all respects. The scope of this invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this invention, and no reference numerals in the claims should be regarded as limiting the content of the claims.

Claims

1. A centerline fitting method for fine-tuning of planar control points after tunnel lining, characterized by: including... The following steps: S1. Obtain the coordinates of the plane control points inside the tunnel, the measured data of the lining cross section, and the fixed tunnel line design parameters; S2. Compare the measured cross-section of the lining with the theoretical clearance profile generated by fitting the centerline according to the line design parameters based on the original control points, calculate the radial and horizontal deviations of each cross-section, and distinguish the overall deviations belonging to the plane control system. S3. Within the allowable tolerance range of the specification, determine the adjustment amount of the coordinates of each plane control point and correct its coordinates, and verify the accuracy of the adjusted control network; the adjustment amount is iteratively solved with the optimization objective of minimizing the weighted sum of the squares of the radial deviation and the horizontal deviation of each section, wherein the weight of the radial deviation and the weight of the horizontal deviation are set based on the maximum allowable over-excavation value and the allowable offset of the building clearance, respectively. S4. Using the adjusted and verified control points as a benchmark, refit the tunnel plane centerline using the original route design parameters. Compare the fitted centerline with the measured cross-section of the lining again. If the over-excavation, under-excavation, and clearance indicators do not meet the requirements, return to S2. Use the cross-section deviation after this fitting as input data to re-execute the deviation tracing and subsequent steps until all cross-sections meet the compliance conditions.

2. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: The weight of the radial deviation is taken as 1 / (ΔR). max ) 2 , where ΔR max The absolute value of the maximum allowable over-excavation is specified; the weight of the horizontal deviation is taken as 1 / (ΔH). max ) 2 , where ΔH max This is the absolute value of the allowable offset of the building clearance.

3. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 2, characterized in that: The iterative optimization is solved using sequential quadratic programming or interior point method, and the calculation of radial and horizontal deviations in each iteration is based on the theoretical net clearance profile generated by the latest centerline after the coordinate refit after this round of adjustment.

4. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: The accuracy verification of the adjusted control network in S3 includes: the relative closure error of the traverse and the positional error of the weakest point meet the relevant requirements of the current tunnel construction specifications, and the absolute value of the difference between the plane coordinates of the adjusted control network inside the tunnel and the control network outside the tunnel does not exceed 25mm for railway tunnels and 20mm for highway tunnels; if the accuracy does not meet the requirements, the constraint weights or data weights in the optimization model are adjusted and the solution is resolved.

5. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: The allowable tolerance in the specification is determined to be ±20mm to ±25mm based on the provisions for the positional error of control points in the traverse survey specifications for highway or railway tunnels, with ±25mm for railway tunnels and ±20mm for highway tunnels.

6. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: The measured data of the lining cross section were collected by a laser profiler in conjunction with a total station with a time interval of no less than 2 seconds. A cross section was collected every 10m on straight sections and every 5m on curved sections.

7. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: In S2, the criteria for determining the overall deviation are: the standard deviation of the deviation vector direction angle of no less than 5 consecutive cross sections is less than 15 degrees, and the coefficient of variation of the vector magnitude is less than 10%; otherwise, it is determined to be a deviation caused by local factors and will not be adjusted. The threshold of the standard deviation of the deviation vector direction angle being less than 15 degrees is derived from the error propagation law and the signal-to-noise ratio being no less than 4. The threshold of the coefficient of variation of the vector magnitude being less than 10% is derived from the measured statistical analysis of multiple tunnel projects.

8. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: in In S1, the fixed line design parameters include the radius of the planar curve, the length of the transition curve, and the geometric angle relationship between each line element; while the coordinates of the center of the circular curve are recalculated and determined based on the fixed geometric parameters and the coordinates of the current control point during each centerline fitting.

9. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: in In S4, the compliance conditions are: the radial under-excavation value of all cross sections is not greater than 0, the over-excavation value is not greater than +50mm, the building clearance does not encroach on the limit and the clearance margin meets the original design requirements.

10. The centerline fitting method for fine-tuning of plane control points after tunnel lining according to claim 1, characterized in that: The method also includes the steps of periodically reviewing and protecting the adjusted plane control points.

Images