Tunnel segment steel bar monitoring point setting structure

Abstract

The utility model provides a tunnel segment reinforcing steel bar monitoring point setting structure which comprises an electrode preformed hole formed in a tunnel segment, a reference electrode inserted in the electrode preformed hole and a pre-embedded terminal pre-embedded in the tunnel segment. The electrode preformed hole and the embedded terminal are both located on the lower portion of the tunnel segment, reinforcing steel bars are arranged in the tunnel segment in the circumferential direction at intervals, the embedded terminal and the reinforcing steel bars are welded and fixed, and the distance between the electrode preformed hole and the embedded terminal ranges from 100 mm to 300 mm. The monitoring point arrangement structure has the advantages that the monitoring point arrangement structure is simple in arrangement mode and can be arranged before the tunnel segment leaves a factory, the embedded terminal and the steel bar are reliably welded, and the arrangement structure is located on the lower portion of the tunnel segment, close to a stray current leakage source, avoids an interval evacuation platform and is convenient to operate and maintain.

Description

Technical Field

[0001] This utility model relates to the field of stray current monitoring technology, specifically to a structure for setting up monitoring points for tunnel segment reinforcement. Background Technology

[0002] In urban rail transit projects, trains use DC 1500V power for traction, receiving power through an overhead contact network and utilizing the train's running rails as the negative return line. When the train is running, the traction current flows back to the traction substation along the return rails, creating a voltage drop on the return rails. This potential difference between the return rails and the ground causes leakage current, which flows in a non-designated circuit—stray current. Stray current can cause electrochemical corrosion to the steel reinforcement of civil structures, the metal casings of equipment, and other underground metal pipelines; this metal corrosion caused by stray current is called stray current corrosion. Therefore, a stray current protection monitoring and control system should be installed, capable of timely and accurate monitoring of the ground potential and stray current of the main building structure's steel reinforcement. Utility Model Content

[0003] The purpose of this utility model is to provide a structure for setting up monitoring points for tunnel segment reinforcement in order to address the shortcomings of the prior art. By setting electrode pre-drilled holes and pre-embedded terminals before the tunnel segments leave the factory, it is convenient to set up reference electrodes and pre-embedded terminals. At the same time, the structure is located at the bottom of the tunnel segments, close to stray current leakage sources, avoiding the evacuation platform of the section, which facilitates operation and maintenance.

[0004] The objective of this utility model is achieved through the following technical solution:

[0005] A structure for setting up monitoring points for rebar in tunnel segments includes electrode pre-drilled holes on the tunnel segments, reference electrodes inserted into the electrode pre-drilled holes, and pre-embedded terminals embedded in the tunnel segments. The electrode pre-drilled holes and the pre-embedded terminals are both located at the lower part of the tunnel segments. Rebars are arranged circumferentially within the tunnel segments. The pre-embedded terminals are welded and fixed to the rebars. The distance between the electrode pre-drilled holes and the pre-embedded terminals is between 100mm and 300mm.

[0006] The diameter of the electrode pre-drilled hole is 60 mm and the depth is 160 mm.

[0007] The tunnel segment is cylindrical, and the electrode pre-reserved hole and the pre-embedded terminal are both located below the horizontal centerline of the tunnel segment and the distance between them and the horizontal centerline of the tunnel segment is in the range of 1500mm~1700mm.

[0008] The number of electrode pre-drilled holes and the number of pre-embedded terminals are both two. The two electrode pre-drilled holes are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment, and the two pre-embedded terminals are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment.

[0009] The space between the electrode pre-drilled hole and the reference electrode is filled with filler.

[0010] The filler is cement mortar.

[0011] The reference electrode is a molybdenum oxide reference electrode.

[0012] The lower part of the embedded terminal is made of steel, and the upper part of the embedded terminal is made of copper. The lower part of the embedded terminal is welded and fixed to the reinforcing bar.

[0013] The resistance at the welding point between the embedded terminal and the reinforcing bar is less than 30 μΩ.

[0014] The advantages of this utility model are: the monitoring point setting structure is simple and can be set before the tunnel segments leave the factory, and the installation process of the reference electrode is fully considered; the pre-embedded terminals are reliably welded to the steel bars, which improves the sampling accuracy of the steel bars; the setting structure is located at the bottom of the tunnel segments, close to the stray current leakage source, which effectively improves the reliability and accuracy of the data, meets the system sampling requirements, and avoids the evacuation platform in the section, which is convenient for operation and maintenance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the tunnel track bed reinforcement in this utility model;

[0016] Figure 2 This is a schematic diagram of the structure of the present invention;

[0017] Figure 3 This is a schematic diagram showing the positions of the electrode pre-drilled holes and embedded terminals in this utility model;

[0018] Figure 4 This is a schematic diagram of the pre-embedded terminal in this utility model. Detailed Implementation

[0019] The features and other related features of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate the understanding of those skilled in the art:

[0020] like Figure 1-4 As shown in the figure, marks 1-5 represent: tunnel segment 1, tunnel track bed reinforcement 2, reference electrode 3, embedded terminal 4, and electrode reserved hole 5, respectively.

[0021] Example: Figure 1-4As shown, this embodiment relates to a structure for setting up monitoring points for rebar in tunnel segments, used to monitor stray currents within tunnel segments. The structure includes electrode pre-drilled holes 5 on the tunnel segment 1, a reference electrode 3 inserted into the electrode pre-drilled holes 5, and pre-embedded terminals 4 pre-embedded in the tunnel segment 1. Both the electrode pre-drilled holes 5 and the pre-embedded terminals 4 are located at the lower part of the tunnel segment 1. In this embodiment, the tunnel segment 1 is circular, with the lower part being the lower half of the circle. Furthermore, rebars are spaced circumferentially within the tunnel segment 1, and the pre-embedded terminals 4 are welded and fixed to the rebars. In other words, the pre-embedded terminals 4 can be pre-embedded during the fabrication of the tunnel segment 1, allowing for convenient welding of the pre-embedded terminals 4 to the rebars. Furthermore, in this embodiment, the distance between the electrode pre-drilled hole 5 and the pre-embedded terminal 4 is between 100mm and 300mm, that is, the distance between the reference electrode 3 and the pre-embedded terminal 4 (steel bar) is between 100mm and 300mm. This can effectively improve the reliability and accuracy of the data and meet the sampling requirements of the monitoring system.

[0022] In this embodiment, by opening electrode pre-reserved holes 5 for placing reference electrodes 3 on the tunnel segment 1 during the prefabrication of the tunnel segment 1, and pre-embedding the pre-embedded terminals 4 in the tunnel segment 1 and welding them to the reinforcing bars, the reliability of the connection between the pre-embedded terminals 4 and the reinforcing bars is improved, the detection accuracy is ensured, and the construction of the setting structure is facilitated. Moreover, this solution can be used for tunnel segments 1 of any connection method, and it has wide applicability.

[0023] In this embodiment, the shield tunnel section is generally composed of 6 rings of tunnel segments 1 connected by a ring network and longitudinal bolts. Each ring of tunnel segments 1 consists of multiple steel bars spaced approximately 15mm apart. Figure 2 As shown, for example, the central angles corresponding to the six-ring tunnel segment 1 are 67.5°, 67.5°, 67.5°, 68.75°, 68.75°, and 20°. In this embodiment, the steel bar connected to the pre-embedded terminal 4 is one steel bar in the tunnel segment 1.

[0024] In this embodiment, optionally, the diameter of the electrode pre-drilled hole 5 is 60 mm and the depth is 160 mm. Its size is slightly larger than that of the reference electrode 3, which facilitates the filling of other materials to achieve fixation and contact between the two.

[0025] In this embodiment, the tunnel segment 1 is cylindrical, and both the electrode pre-drilled hole 5 and the embedded terminal 4 are located below the horizontal centerline of the tunnel segment 1. The distance between the electrode pre-drilled hole 5, the embedded terminal 4, and the horizontal centerline of the tunnel segment 1 is between 1500mm and 1700mm. This facilitates the connection of the reference electrode 3, the embedded terminal 4, and the monitoring device. Furthermore, since stray current leaks from the rail and enters the tunnel segment 1, the lower part of the tunnel segment 1 is close to the leakage source and located above the rail, improving monitoring accuracy and facilitating later inspection and maintenance. Figure 2 As shown, the tunnel track bed reinforcement 2 is insulated from the rail, and the lower part of the tunnel segment 1 is close to the leakage source.

[0026] In this embodiment, there are two electrode pre-drilled holes 5 and two pre-embedded terminals 4. The two electrode pre-drilled holes 5 are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment 1, and the two pre-embedded terminals 4 are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment 1. That is, one pre-embedded terminal 4 needs to be pre-embedded on each of the two side walls of the circular tunnel segment 1, and for each pre-embedded terminal 4, an electrode pre-drilled hole 5 is reserved within a range of no more than 100~300mm, and a reference electrode 3 is installed in the electrode pre-drilled hole 5.

[0027] In this embodiment, the aforementioned structure can be constructed in tunnel segment 1, approximately 200m from both ends of the station within the shield tunnel section. The location of approximately 200m from the station is chosen because this location provides representative data on the acceleration and deceleration points of vehicles leaving and entering the station.

[0028] In this embodiment, optionally, the electrode pre-drilled hole 5 and the reference electrode 3 are filled with filler. For example, the filler is cement mortar. In this embodiment, the installation process of the reference electrode 3 is as follows: (1) Before installation, remove the concrete powder or dust in the electrode pre-drilled hole 5 and wet the inner surface with tap water; (2) To ensure the stability of the reference electrode 3, the reference electrode 3 should be buried near the steel bars of the structure being measured as much as possible, the reference electrode 3 should be placed vertically, and the reference electrode 3 should be completely buried in the concrete medium; (3) Mix the pre-prepared cement mortar filler with tap water until the temperature is suitable, then put a small amount of mortar into the bottom of the electrode pre-drilled hole 5, and apply the mortar to the surrounding walls, paying attention to even application; (4) Apply a layer of mortar to the ceramic shell of the reference electrode 3, and gently place it into the electrode pre-drilled hole 5 until the ideal depth is reached. The lead wire of the reference electrode 3 is reserved with a length of 3m for easy connection with the monitoring device.

[0029] In this embodiment, optionally, the reference electrode 3 is a molybdenum oxide reference electrode 3, which can be installed inside the tunnel segment 1. The reference electrode 3 has the characteristics of stable potential, vibration resistance, and long service life. Specifically, the reference electrode 3 type is a Mo / MoO3 reference electrode 3; potential stability is ≤±20mV; electrode polarizability is <30mV under a polarization current density <5μA / cm²; electrode service life is not less than 10 years; electrode shell is a ceramic shell with a compressive strength ≥10MPa; electrode size is not greater than F50--150mm; and the lead cable length is ≥5m.

[0030] In this embodiment, optionally, the lower part of the embedded terminal 4 is made of steel, using reinforcing bars, which facilitates reliable welding with the reinforcing bars of the tunnel segment 1 during pre-embedding at the tunnel segment 1 factory. Optionally, the upper part of the embedded terminal 4 is made of copper, which can reduce contact resistance and improve the monitoring accuracy of the reinforcing bar polarization potential. Reliable welding between the upper and lower parts of the terminal allows for factory-produced finished products.

[0031] In some embodiments, the copper content in the upper part of the embedded terminal 4 should be ≥99%, the overall continuous current carrying capacity should be ≥600A, and the welding resistance between the embedded terminal 4 and the reinforcing bar should be less than 30μΩ, i.e., the welding resistance ≤30uΩ. Each set of embedded terminals 4 should be provided with a set of M16 bolts and protective caps. During the segment processing, the embedded terminals 4 and electrode pre-drilled holes 5 should be prevented from being covered by concrete to facilitate the later connection of test cables and the installation of reference electrodes 3.

[0032] In summary, the beneficial effects of this utility model are: (1) The setting method is simple and can be set before the tunnel segments leave the factory. It fully considers the installation process of the reference electrode and the welding reliability of the pre-embedded terminal and the tunnel segment reinforcement. (2) The upper part of the terminal structure is made of copper and the lower part is made of steel, which effectively reduces the resistance and improves the accuracy of monitoring polarization potential. (3) The setting position is reasonable. The horizontal setting is about 200m in the section, which fully considers the running train, starting acceleration, braking and deceleration conditions, and the data is more representative. In the vertical direction, the monitoring point is located at the lower part of the segment, close to the stray current leakage source, avoiding the section evacuation platform, which is convenient for operation and maintenance. (4) The connection method is reliable. The pre-embedded terminal is reliably welded to the reinforcement, which improves the sampling accuracy of the structural reinforcement. The reference electrode is set near the pre-embedded terminal, which effectively improves the data reliability and accuracy and meets the sampling requirements of the monitoring system. (5) It has wide adaptability. There are generally two connection methods for tunnel segments in the section: bolt connection or socket joint. Regardless of the structural form of the tunnel segment, this scheme can be used to set the monitoring point, which can meet any tunnel segment form.

[0033] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “a” or “one,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “connected” or “linked,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, which change accordingly when the absolute position of the described object changes.

[0034] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A structure for setting up monitoring points for tunnel segment reinforcement, characterized in that, The setup includes electrode pre-drilled holes on the tunnel segment, a reference electrode inserted into the electrode pre-drilled holes, and pre-embedded terminals embedded in the tunnel segment. Both the electrode pre-drilled holes and the pre-embedded terminals are located at the lower part of the tunnel segment. Reinforcing bars are spaced apart circumferentially inside the tunnel segment. The pre-embedded terminals are welded and fixed to the reinforcing bars. The distance between the electrode pre-drilled holes and the pre-embedded terminals is between 100mm and 300mm.

2. The configuration structure according to claim 1, characterized in that, The diameter of the electrode pre-drilled hole is 60 mm and the depth is 160 mm.

3. The configuration structure according to claim 1, characterized in that, The tunnel segment is cylindrical, and the electrode pre-reserved hole and the pre-embedded terminal are both located below the horizontal centerline of the tunnel segment and the distance between them and the horizontal centerline of the tunnel segment is in the range of 1500mm~1700mm.

4. The arrangement structure according to claim 3, characterized in that, The number of electrode pre-drilled holes and the number of pre-embedded terminals are both two. The two electrode pre-drilled holes are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment, and the two pre-embedded terminals are symmetrically arranged about the vertical plane passing through the axis of the tunnel segment.

5. The configuration structure according to claim 1, characterized in that, The space between the electrode pre-drilled hole and the reference electrode is filled with filler.

6. The arrangement structure according to claim 5, characterized in that, The filler is cement mortar.

7. The arrangement structure according to claim 1, characterized in that, The reference electrode is a molybdenum oxide reference electrode.

8. The arrangement structure according to claim 1, characterized in that, The lower part of the embedded terminal is made of steel, and the upper part of the embedded terminal is made of copper. The lower part of the embedded terminal is welded and fixed to the reinforcing bar.

9. The arrangement structure according to claim 1, characterized in that, The resistance at the welding point between the embedded terminal and the reinforcing bar is less than 30 μΩ.

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