A high-precision railway span active fracture deformation monitoring method

Abstract

A high-precision railway deformation monitoring method across active fractures is provided to effectively meet the needs of high-precision deformation monitoring of active fractures. The method includes the following steps: laying out a monitoring network to form a corner intersection network that is a mixture of forced centering stations and free stations; numbering all monitoring prisms, measuring and recording the constant difference of the prisms; selecting two prisms with the same prism constant and combining them with a total station to determine the comprehensive addition constant of the total station, and inputting this into the instrument as the instrument addition constant for subsequent measurements; selecting the deformation monitoring point closest to the direction point as the reference point, setting instruments at the reference point and the deformation monitoring point to measure the direction and distance of all deformation monitoring points and direction points, and measuring at least two rounds for each point; observing the direction and distance of the reference point and each deformation monitoring point in turn through 4 free stations; performing adjustment calculations, and arranging them into deformation analysis tables and deformation analysis diagrams.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a high-precision railway span active fracture deformation monitoring method. Background Art

[0002] At present, the main monitoring method for active fault zones is to use the global satellite navigation system (GNSS) continuously or through static observation post-processing, but the results obtained by GNSS in a small range cannot meet the needs of high-precision monitoring of special active fault zones. GNSS cannot meet the monitoring needs in mountainous areas and densely forested areas due to poor satellite signals. Leveling is mostly used for elevation measurement.

[0003] The purpose of railway cross-active fault monitoring is to analyze the movement and changes of the fault zone and its impact on railway engineering, and to provide scientific support data for safety warning and emergency rescue decisions of railway engineering. With the planning and construction of the national western railway, it is inevitable that the construction railway tunnel will pass under the existing active fault zone. In order to ensure the safety of railway construction, deformation monitoring is required. On the other hand, after the railway tunnel is completed and put into operation, the safe operation of the railway tunnel can be guaranteed by monitoring the deformation of the active fault zone. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a high-precision railway deformation monitoring method across active fractures, so as to effectively meet the needs of high-precision active fracture deformation monitoring and ensure the safety of railway construction and operation.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0006] A high-precision railway span active fracture deformation monitoring method of the present invention comprises the following steps:

[0007] ① Lay out the monitoring network, with the monitoring point line perpendicular to the active fault zone. Set at least three deformation monitoring points on both sides of the active fault zone at intervals of about 20m on the monitoring point line, and set a direction point at least 60m outside the deformation monitoring point on one side. Bury the forced centering mark at the direction point and each deformation monitoring point, and add 4 free stations at 5m to 20m on both sides of the monitoring point line to form a corner intersection network that mixes forced centering stations and free stations;

[0008] ②Number all prisms used for monitoring, measure the constant difference of the prisms and record them;

[0009] ③ Select two prisms with the same prism constant and combine them with the total station to determine the comprehensive addition constant of the total station, and input this into the instrument as the instrument addition constant for subsequent measurements;

[0010] ④ Select the deformation monitoring point closest to the direction point as the reference point, set up instruments at the reference point and deformation monitoring point to measure the direction and distance of all deformation monitoring points and direction points, and measure at least two rounds for each point;

[0011] ⑤ Observe the direction and distance between the benchmark point and each deformation monitoring point in turn through 4 free stations;

[0012] ⑥ Adjustment calculation and organize it into deformation analysis tables and deformation analysis diagrams.

[0013] The beneficial effect of the present invention is that a method combining free station setting and traditional station setting is introduced for monitoring, which has high monitoring accuracy and can effectively meet the needs of high-precision railway deformation monitoring across active fractures, thereby ensuring the safety of railway construction and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] This specification includes the following three drawings:

[0015] Figure 1 It is a schematic diagram of the layout of a monitoring network for a high-precision railway span active fracture deformation monitoring method of the present invention;

[0016] Figure 2 is a deformation curve diagram of the embodiment in the X direction;

[0017] Figure 3 is a deformation curve diagram of the embodiment in the Y direction;

[0018] The figure shows the components and corresponding marks: active fault zone A, monitoring point connection line B, deformation monitoring point 1, direction point 2, and free station 3. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0020] Reference Figure 1 A high-precision railway deformation monitoring method across active fractures of the present invention comprises the following steps: ① laying out a monitoring network, wherein a monitoring point line B is perpendicular to an active fracture zone A, and at least three deformation monitoring points 1 are arranged on the monitoring point line B on both sides of the active fracture zone A at intervals of about 20 m, and a direction point 2 is arranged at least 60 m outside the deformation monitoring point 1 on one side, and a forced centering mark (observation pier) is buried at the direction point 2 and each deformation monitoring point 1, and 4 free stations 3 are added at 5 m to 20 m on both sides of the monitoring point line B to form a corner intersection network of a mixture of forced centering stations and free stations;

[0021] ②Number all prisms used for monitoring, measure the constant difference of the prisms and record them;

[0022] ③ Select two prisms with the same prism constant and combine them with the total station to determine the comprehensive addition constant of the total station, and input this into the instrument as the instrument addition constant for subsequent measurements;

[0023] ④ Select the deformation monitoring point closest to the direction point as the reference point, set up instruments at the reference point and deformation monitoring point 1 to measure the direction and distance of all deformation monitoring points 1 and direction point 2, and measure at least two rounds for each point;

[0024] ⑤ Observe the direction and distance between the benchmark point and each deformation monitoring point 1 in turn through four free stations 3;

[0025] ⑥ Adjustment calculation and organize it into deformation analysis tables and deformation analysis diagrams.

[0026] In step ③, a total station with a nominal accuracy of not less than 1″, 1mm+1ppm is used for measurement, and the total station has the functions of automatic target search, automatic aiming, automatic observation, and automatic recording.

[0027] In step ①, the deformation monitoring points 1 are spaced at intervals of 20 m.

[0028] High-precision deformation monitoring requires fixed instruments, fixed equipment, and fixed mesh shapes, so only steps ④ to ⑥ are required for the second phase and beyond. If the instrument has been used for more than 1 year or is damaged and must be replaced, repeat steps ② to ⑥.

[0029] Accuracy analysis:

[0030] (1) Free site setting part

[0031] According to the cosine theorem, the horizontal distance D between any two monitoring points is known. AB The exact value of can be expressed by formula (1):

[0032]

[0033] Where: D CA , D CB represents the measured horizontal distance, and C represents the measured angle of the freely set station.

[0034] Taking the total differential of equation (1) and simplifying it, we get:

[0035]

[0036] When the station is located in the middle of the monitoring point, due to the equal precision observation of the side length, according to the error propagation law, the horizontal distance D AB The mean error can be expressed as:

[0037]

[0038] In the above formula, m SIndicates the side length measurement accuracy, m C Indicates the horizontal angle measurement accuracy.

[0039] Since the distance between monitoring points is basically 20 meters, the instrument is set up in the middle, and the angle is between 170° and 190°:

[0040]

[0041] From formula (4), we can see that when the horizontal angle observation accuracy is 6", the angle measurement accuracy is only AB The maximum value of the impact is about 0.025 mm, so the third side measurement accuracy is mainly affected by the distance measurement accuracy.

[0042] Therefore, formula (4) can be simplified as:

[0043]

[0044] According to the literature "Research on the determination method of total station additive constant based on free station setting", the comprehensive additive constant of the total station can reach 0.25 mm. The influence of free station setting on the monitoring points is affected by the distance. When the observation distance is 60 meters, the observation accuracy is about 0.44 mm. When setting stations at other locations, the conclusion of formula (5) can also be obtained by deduction.

[0045] (2) Monitoring point setting part

[0046] When the instrument is set up at the monitoring point, it is a direct measurement, so the horizontal distance D AB The exact value of is obtained by direct measurement with a total station, which depends on the distance measurement accuracy of the total station. AB When the observation distance is 60 meters, the observation accuracy is about 0.31mm.

[0047] (3) Overall accuracy analysis

[0048] When setting up stations freely, adjacent monitoring points are measured independently three times, and the accuracy is:

[0049]

[0050] When setting up monitoring points, adjacent monitoring points are measured independently three times, and their accuracy is:

[0051]

[0052] Therefore, the comprehensive monitoring accuracy of adjacent monitoring points is:

[0053]

[0054] If 3 times the mean error is taken as the extreme error, then the accuracy limit of the distance between adjacent points should be 0.45mm. Taking into account the influence of other unconsidered parts, 0.50mm can be taken as the limit.

[0055] Example:

[0056] A fault zone was monitored for 9 periods, and the observation accuracy of the distance to the weakest edge is as follows:

[0057] Table 1 Statistics of the observation accuracy of the weakest edge

[0058] Issue 1 Issue 2 Issue 3 Issue 4 Issue 5 Issue 6 Issue 7 Issue 8 Issue 9 0.36 0.41 0.29 0.11 0.22 0.12 0.14 0.44 0.23

[0059] It can be seen from the above table that the weakest edges of the 9 observations did not exceed the limit requirements.

[0060] Statistics of deformation in the X direction of a fault zone:

[0061] Table 2 X-direction deformation statistics

[0062]

[0063] Table 3 Y-direction deformation statistics

[0064]

Claims

1. A high-precision railway span active fracture deformation monitoring method, comprising the following steps: ① Lay out a monitoring network, with the monitoring point line (B) perpendicular to the active fault zone (A). Set at least three deformation monitoring points (1) on both sides of the active fault zone (A) on the monitoring point line (B) at intervals of about 20m, and set a direction point (2) at least 60m outside the deformation monitoring point (1) on one side. Bury a forced centering mark (observation pier) at the direction point (2) and each deformation monitoring point (1). Add 4 free stations (3) at 5m to 20m on both sides of the monitoring point line (B), forming a corner intersection network that mixes forced centering stations with free stations. ②Number all prisms used for monitoring, measure the constant difference of the prisms and record them; ③ Select two prisms with the same prism constant and combine them with the total station to determine the comprehensive addition constant of the total station, and input this into the instrument as the instrument addition constant for subsequent measurements; ④ Select the deformation monitoring point closest to the direction point as the reference point, set up instruments at the reference point and deformation monitoring point (1) to measure the directions and distances of all deformation monitoring points (1) and direction points (2), and measure at least two rounds for each point; ⑤ Observe the direction and distance between the benchmark point and each deformation monitoring point (1) in turn through four free stations (3); ⑥ Adjustment calculation and organize it into deformation analysis tables and deformation analysis diagrams.

2. A high-precision railway span active fracture deformation monitoring method as claimed in claim 1, characterized in that: In step ③, a total station with a nominal accuracy of not less than 1″, 1mm+1ppm is used for measurement, and the total station has the functions of automatic target search, automatic aiming, automatic observation, and automatic recording.

3. A high-precision railway span active fracture deformation monitoring method as claimed in claim 1, characterized in that: In step ①, the deformation monitoring points (1) are spaced 20 m apart.

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