An underground space structure crack monitoring system and a crack monitoring method thereof

Abstract

The application discloses an underground space structure crack monitoring system and a crack monitoring method thereof, which comprises a dot distribution detection system and a crack measuring device; the dot distribution detection system comprises a plurality of conductive thin rings arranged at wall connecting positions, the conductive thin rings are open ring structures with notches, both ends of the conductive thin rings at the notches are provided with contacts, and the two contacts are located on a wall integrally poured; the dot distribution detection system further comprises a detection mechanism for detecting whether the two contacts of the conductive thin rings are conductive; the crack measuring device comprises fixing heads fixed on wall boreholes at both sides of the crack, and a tension line sensor for measuring the interval is arranged between the two fixing heads; the crack at the wall connecting position can be monitored by periodically conducting the conductive test on the conductive thin rings through the detection mechanism; and meanwhile, when the crack exists, the change of the crack can be monitored through the crack measuring device after the crack is treated.

Description

Technical Field

[0001] This invention relates to the field of crack detection and treatment technology, specifically to a crack monitoring system and method for underground space structures. Background Technology

[0002] Currently, most underground space buildings are constructed using concrete pouring techniques. The resulting underground space buildings have good overall integrity, which can improve the building's sturdiness. When constructing larger buildings, since the walls cannot be constructed using a single pouring process, a multi-segment pouring process is usually used. This multi-segment pouring process can also ensure that the building has high sturdiness after completion.

[0003] In existing underground walls constructed in multiple sections, cracks can easily occur between the first and second sections due to factors such as vibration, temperature, stress, and thermal expansion and contraction of concrete. This can cause groundwater to easily seep through the connection between the first and second sections, leading to leakage and affecting the normal use of the underground space.

[0004] Therefore, in order to ensure the safe operation of underground space buildings, how to monitor wall cracks is an urgent problem to be solved. Current crack detectors generally measure crack changes by measuring the change in the distance between two points. However, for large underground space buildings, there are many measurement points, so a large number of crack detectors need to be installed, which is time-consuming, labor-intensive, and greatly increases the cost of crack detection. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides an underground space structure crack monitoring system and method, which solves the problems of high difficulty and high cost in monitoring cracks in underground space structures.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] Firstly, a crack monitoring system for underground space structures is provided, comprising a point detection system for detecting the presence of cracks at wall joints and a crack measuring device for measuring changes in cracks at wall joints. The point detection system includes several conductive thin rings placed at the wall joints. Each conductive thin ring is an open-loop structure with a notch. Contact points are provided at both ends of the conductive thin rings at the notches, and both contact points are located on a monolithically cast wall. The point detection system also includes a detection mechanism for detecting whether the two contact points of the several conductive thin rings are conductive. The crack measuring device includes fixed heads fixed to boreholes in the wall on both sides of the crack. A pull-wire sensor for measuring the distance is provided between the two fixed heads. A piston rod and a sleeve are respectively provided on the two fixed heads, and the piston rod and the sleeve slide and extend in cooperation. A guide wheel is provided at one end of the sleeve near the fixed head. The front end of the pull-wire sensor is fixed to the front end of the piston rod, and the pull-wire passes around the guide wheel and passes through the rear end of the piston rod to connect with the pull-wire sensor. An expansion mechanism for fixed contact with the inner wall of the borehole in the wall is provided on the outer wall of the fixed head.

[0008] Furthermore, the detection mechanism includes a horizontal bar located on one side of the wall, on which a motion unit is slidably mounted. The motion unit is connected to a transition unit via a first telescopic mechanism, and the motion directions of the motion unit and the transition unit are perpendicular to each other and parallel to the wall. The transition unit is connected to the detection unit via a second telescopic mechanism, and the extension direction of the second telescopic mechanism is perpendicular to the wall.

[0009] Furthermore, the detection unit includes an automatic positioning module and two contact heads that respectively contact two contacts of several conductive thin rings. The two contact heads are electrically connected to the continuity detection circuit. The automatic positioning module includes a camera module and a computer module. The motion unit, the first telescopic mechanism, the second telescopic mechanism, the continuity detection circuit, and the camera module are all electrically connected to the computer module.

[0010] Furthermore, the piston rod and sleeve are respectively hinged to the two fixed heads, and the rotating surface at the hinge is perpendicular to the wall.

[0011] Furthermore, the expansion mechanism includes support heads arranged on both sides of the fixed head, with magnetic blocks and telescopic rods arranged sequentially on the inner side of the support heads. The telescopic rods are arranged radially on the side wall of the fixed head, and a magnetic mechanism for driving the magnetic blocks to move radially is provided inside the fixed head.

[0012] Furthermore, the fixed head is provided with two sliding grooves, and the magnetic mechanism includes magnetic drive blocks movably disposed in the sliding grooves. The front ends of the two magnetic drive blocks are connected by connecting ropes, and the front end of the fixed head is provided with a pulley that cooperates with the connecting ropes. The rear ends of the two magnetic drive blocks are respectively connected to the front ends of two traction ropes, and the rear ends of the two traction ropes both pass through the fixed head. The magnetic drive blocks include N-pole magnetic blocks and S-pole magnetic blocks, and the relative positions of the N-pole magnetic blocks and S-pole magnetic blocks in the two magnetic drive blocks are opposite.

[0013] Secondly, a crack monitoring method for an underground space structure crack monitoring system is provided, which includes the following steps:

[0014] S1: Using the splicing center of four adjacent cast-in-place wall sections arranged in a grid pattern as the center, an annular groove is opened on the wall surface, and a conductive thin ring is fixed in the annular groove;

[0015] S2: The testing agency conducts a conductivity test on each of the conductive thin rings on the wall. If there is a non-conductive conductive thin ring, the conductive thin ring at the corresponding position is reinstalled and the conductivity test is repeated until all conductive thin rings are conductive.

[0016] S3: After a preset time interval, the conductivity of several conductive thin rings on the wall is tested one by one by the testing agency. If there are non-conductive conductive thin rings, the position is marked and step S4 is executed. If all conductive thin rings are conductive, step S3 is repeated to continuously and periodically test several conductive thin rings.

[0017] S4: Using the location mark as the center, observe the connection between two adjacent cast-in-place walls in all directions until a crack is found at the wall connection.

[0018] S5: After repairing and reinforcing the crack, drill holes in the walls on both sides of the crack and fix the two fixing heads of the crack measuring device into the two drill holes respectively.

[0019] S6: Periodically check the change in the pull wire sensor. If the change is zero, reinstall a new conductive thin ring at the location mark, remove the crack measuring device, and return to step S3. If the change is not zero, continue to repair and reinforce the crack until the change in the pull wire sensor is zero.

[0020] Furthermore, the method by which the testing mechanism performs conductivity tests on each of the several conductive thin rings in step S2 includes:

[0021] S21: The two contact heads on the detection unit are driven by the motion unit, the first telescopic mechanism and the second telescopic mechanism to connect sequentially with two contacts on several conductive thin rings, and the conductivity of the conductive thin rings is tested by the continuity detection circuit.

[0022] S22: Each time the two contact heads connect with the two contact points, the computer module records the amount of motion of the motion unit, the first telescopic mechanism, and the second telescopic mechanism, and summarizes the position coordinates of the detection unit and each conductive thin ring, and saves the position coordinates in the computer module.

[0023] The method for the detection mechanism to perform conductivity tests on several conductive thin rings one by one in step S3 includes: calling the position coordinates in the computer module, controlling the detection unit to automatically move to several position coordinates, and observing the docking of the two contact heads with the two contact points through the camera module. If there is a docking deviation, the position of the detection unit is adjusted through the motion unit, the first telescopic mechanism and the second telescopic mechanism until the two contact heads are docked with the two contact points. Then, the conductivity test of the conductive thin rings is performed through the continuity detection circuit.

[0024] Furthermore, the method for fixing the fixing head inside the borehole in step S5 includes:

[0025] S51: By pulling a traction rope, two magnetic drive blocks are moved to slide in two sliding grooves respectively, until one of the N-pole magnetic block and the S-pole magnetic block of each magnetic drive block aligns with the magnetic block and attracts each other.

[0026] S52: Place the fixing head inside the drill hole and pull another traction rope to cause the two magnetic drive blocks to slide in opposite directions in the two sliding grooves until one of the N-pole magnetic block and S-pole magnetic block of each magnetic drive block aligns with the magnetic block and repels each other.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. This solution involves placing a conductive thin ring on the wall surface at the center of the joint of four adjacent cast-in-place walls. When a crack appears at the joint of any two of the four cast-in-place walls, the conductive thin ring will break due to the displacement caused by the crack, thus rendering the conductive thin ring ineffective. By conducting periodic conductivity tests on the conductive thin ring by a testing agency, the cracks at the joint of the walls can be monitored.

[0029] 2. One conductive thin ring in this solution can simultaneously detect four adjacent cast-in-place walls. The conductive thin ring has slight toughness, so it will not break when the wall experiences slight vibration or when a small crack appears at the wall joint. The conductive thin ring will only break when the crack width reaches a certain value. At the same time, compared with setting up several crack measuring instruments at the wall joints, the conductive thin ring in this solution is inexpensive, thus greatly reducing the cost of crack monitoring.

[0030] 3. After the conductive rings are installed, this solution uses a drive detection unit to perform a pre-conductivity test on the rings to ensure that each ring is in a valid state. Subsequent periodic conductivity tests on the rings can be automated using the position coordinates saved during the pre-conductivity test, simplifying subsequent conductivity testing operations. To prevent contact point displacement on the wall due to cracks, the automated conductivity test also requires the use of a camera module and position adjustment of the detection unit to ensure that each contact head is aligned with two contact points.

[0031] 4. When cracks are detected at the wall joints, this solution repairs and reinforces the cracks. Furthermore, crack measurement devices can monitor changes in the cracks. These devices are easy to install and remove; installation simply requires drilling holes in the walls on both sides of the crack. By pulling the traction rope, the magnetic drive blocks attract or repel each other, thus driving the support head to extend and retract under magnetic force. When the fixed head needs to be fixed, the support head extends and rests against the inner wall of the drilled hole using magnetic force. When the fixed head needs to be removed, the support head retracts using magnetic force.

[0032] 5. The fixing method of the fixing head and the drill hole in this solution is not rigid. When the wall on both sides of the crack is misaligned parallel to the wall surface, the fixing head can rotate slightly in the drill hole under the deflection of the piston rod and the sleeve. When the wall on both sides of the crack is misaligned perpendicular to the wall surface, the piston rod and the sleeve can deflect at the hinge, so as not to affect the limiting fixation of the fixing head and the measurement of the pull wire sensor. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the testing organization.

[0034] Figure 2 This is an end view of the detection unit.

[0035] Figure 3 This is a side view of the detection unit.

[0036] Figure 4 This is a schematic diagram of the crack measuring device during the contraction of the support head.

[0037] Figure 5 This is a schematic diagram of the crack measuring device during the extension of the support head.

[0038] Figure 6 A schematic diagram of a conductive thin ring installed on a wall.

[0039] Figure 7 This is a schematic diagram of the structure of a conductive thin ring.

[0040] Among them, 1. conductive thin ring, 2. contact point, 3. fixed head, 4. pull wire sensor, 5. crossbar, 6. motion unit, 7. first telescopic mechanism, 8. transition unit, 9. second telescopic mechanism, 10. detection unit, 11. contact head, 12. camera module, 13. piston rod, 14. sleeve, 15. guide wheel, 16. pull wire, 17. support head, 18. magnetic block, 19. telescopic rod, 20. sliding groove, 21. connecting rope, 22. pulley, 23. traction rope, 24. N pole magnetic block, 25. S pole magnetic block, 26. rotating gimbal, 27. handle, 28. wall, 29. annular groove, 30. rotating shaft, 31. hinge ear. Detailed Implementation

[0041] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0042] Example 1

[0043] like Figures 1 to 7 As shown, the underground space structure crack monitoring system of this scheme includes a point detection system for detecting whether there are cracks at the connection of the wall 28 and a crack measuring device for measuring the changes of cracks at the connection of the wall 28. The point detection system includes several conductive thin rings 1 placed at the connection of the wall 28. The conductive thin ring 1 is an open-loop structure with a notch. The two ends of the conductive thin ring 1 at the notch are provided with contact points 2, and the two contact points 2 are located on a single integrally cast wall 28. The point detection system also includes a detection mechanism for detecting whether the two contact points 2 of the several conductive thin rings 1 are conductive. The crack measuring device includes a fixing head 3 fixed on the boreholes of the wall 28 on both sides of the crack. A pull wire sensor 4 for measuring the spacing is set between the two fixing heads 3.

[0044] Example 2

[0045] like Figures 1 to 3As shown, this embodiment provides a specific scheme for the detection mechanism based on embodiment 1. The detection mechanism includes a horizontal bar 5 located on one side of the wall 28. A motion unit 6 is slidably disposed on the horizontal bar 5. The motion unit 6 is connected to the transition unit 8 through a first telescopic mechanism 7. The motion directions of the motion unit 6 and the transition unit 8 are perpendicular to each other and parallel to the wall 28. The transition unit 8 is connected to the detection unit 10 through a second telescopic mechanism 9. The extension direction of the second telescopic mechanism 9 is perpendicular to the wall 28. Through the coordinated movement of the motion unit 6, the first telescopic mechanism 7, and the second telescopic mechanism 9, the detection unit 10 can move in the three-dimensional space on one side of the wall 28.

[0046] The detection unit 10 includes two contact heads 11 that respectively contact two contacts 2 of a plurality of conductive thin rings 1. The two contact heads 11 are electrically connected to the continuity detection circuit. The detection unit 10 also includes an automatic positioning module, which includes a camera module 12 and a computer module. The motion unit 6, the first telescopic mechanism 7, the second telescopic mechanism 9, the continuity detection circuit, and the camera module 12 are all electrically connected to the computer module.

[0047] When cracks appear at the joints of the cast-in-place wall 28, the conductive thin ring 1 will break due to the displacement caused by the cracks, thus rendering the conductive thin ring 1 ineffective. The conductive thin ring 1 can then be periodically tested for conductivity by the detection unit 10, thereby enabling the monitoring of cracks at the joints of the wall 28. At the same time, compared with setting up several crack measuring instruments at the joints of the wall 28, the conductive thin ring 1 in this solution is inexpensive, thus greatly reducing the cost of crack monitoring.

[0048] Specifically, in the implementation of this solution, the continuity detection circuit can detect whether the conductive thin ring 1 is open or closed, and transmit the open or closed signal to the computer module. The continuity detection circuit adopts existing circuits or equipment used to detect the continuity of the line, such as the ohm resistance range or continuity range of a multimeter, which can detect the continuity of the line. Therefore, the specific structure of the continuity detection circuit will not be described in detail. In order to detect the displacement of the motion unit 6, the first telescopic mechanism 7, and the second telescopic mechanism 9, displacement sensors electrically connected to the computer module can be set on the motion unit 6, the first telescopic mechanism 7, and the second telescopic mechanism 9 respectively. The two contact heads 11 can be set on the rotating gimbal 26, which is mounted on the detection unit 10, so that the contact heads 11 can be made to contact the offset contact points 2 on the wall 28 by rotating the gimbal 26.

[0049] Example 3

[0050] like Figure 4 and Figure 5As shown, this embodiment provides a specific solution for the fixed head 3 and the pull wire sensor 4 based on embodiment 1. The outer wall of the fixed head 3 is provided with an expansion support mechanism for fixed contact with the inner wall of the hole drilled in the wall 28. The expansion support mechanism includes support heads 17 arranged on both sides of the fixed head 3. Magnetic blocks 18 and telescopic rods 19 are arranged sequentially on the inner side of the support heads 17. The telescopic rods 19 are arranged radially on the side wall of the fixed head 3. A magnetic mechanism for driving the magnetic blocks 18 to move radially is provided inside the fixed head 3.

[0051] The fixed head 3 has two sliding grooves 20. The magnetic mechanism includes a magnetic drive block movably disposed in the sliding groove 20. The middle of the magnetic drive block is provided with a strip hole for avoiding the telescopic rod 19, so as to avoid interference between the telescopic rod 19 and the magnetic drive block. The front ends of the two magnetic drive blocks are connected by a connecting rope 21, and the front end of the fixed head 3 is provided with a pulley 22 that cooperates with the connecting rope 21. The rear ends of the two magnetic drive blocks are respectively connected to the front ends of two traction ropes 23, and the rear ends of the two traction ropes 23 both pass out of the fixed head 3 and are provided with a handle 27. The magnetic drive block includes an N-pole magnetic block 24 and an S-pole magnetic block 25, and the relative positions of the N-pole magnetic block 24 and the S-pole magnetic block 25 in the two magnetic drive blocks are opposite.

[0052] The fixing head 3 of this solution is easy to install and remove. During installation, it is only necessary to drill holes in the wall 28 on both sides of the crack. By pulling the traction rope 23, the magnetic drive block and the magnetic block 18 can attract or repel each other, thereby driving the support head 17 to extend and retract under the action of magnetic force. When the fixing head 3 needs to be fixed, the support head 17 can be extended by magnetic force and supported on the inner wall of the drill hole. When the fixing head 3 needs to be installed or removed, the support head 17 can be retracted by magnetic force. The polarity of the magnetic block 18 can be either N or S. Taking the N polarity of the magnetic block as an example, using the principle of like poles repelling and unlike poles attracting, when the N pole magnetic block 24 of the magnetic drive block is facing the magnetic block, the support head 17 extends outward under the action of magnetic repulsion, so that the support head 17 abuts against the inner wall of the drill hole; when the S pole magnetic block 25 of the magnetic drive block is facing the magnetic block, the support head 17 retracts inward under the action of magnetic attraction, so as to facilitate the assembly and disassembly of the fixing head 3.

[0053] In this design, two fixed heads 3 are respectively equipped with piston rods 13 and sleeves 14, and the piston rods 13 and sleeves 14 are hinged to the two fixed heads 3 respectively. The rotation surface at the hinge is perpendicular to the wall 28. The piston rods 13 and sleeves 14 are in sliding telescopic cooperation. A guide wheel 15 is provided at one end of the sleeve 14 near the fixed head 3. The front end of the pull wire 16 in the pull wire sensor 4 is fixed to the front end of the piston rod 13, and the pull wire 16 passes around the guide wheel 15 and exits from the rear end of the piston rod 13. The piston rod 13 passes through the fixed head 3 and connects to the pull wire sensor 4 installed on the outside of the fixed head 3. To avoid the hinge of the piston rod 13 and the fixed head 3 affecting the threading of the pull wire 16, the hinge of the piston rod 13 and the fixed head 3 can be as follows: a rotating shaft 30 is provided on the side wall of the end of the piston rod 13, and a hinge ear 31 that cooperates with the rotating shaft 30 is provided on the fixed head 3. The pull wire 16 can pass through the inside of the piston rod 13 and the fixed head 3, and the pull wire 16 and the traction rope 23 do not interfere with each other.

[0054] When the width of the crack changes or the walls 28 on both sides of the crack shift, the distance between the two fixing heads 3 will also change, thereby causing the piston rod 13 to slide and extend within the sleeve 14. The amount of extension and retraction of the piston rod 13 is the displacement of the pull wire 16. Therefore, by detecting the displacement of the pull wire 16 through the pull wire sensor 4, the change of the crack can be detected.

[0055] Specifically, the fixing method of the fixing head 3 and the drill hole in this solution is not rigid, so that when the wall 28 on both sides of the crack is misaligned parallel to the wall surface, the fixing head 3 can rotate slightly in the drill hole under the deflection of the piston rod 13 and the sleeve 14; and when the wall 28 on both sides of the crack is misaligned perpendicular to the wall surface, the piston rod 13 and the sleeve 14 can both deflect at the hinge, so as not to affect the limiting fixation of the fixing head 3 and the measurement of the pull wire sensor 4.

[0056] Based on embodiments 1-3 above, this solution provides a crack monitoring method for an underground space structure crack monitoring system, which includes the following steps:

[0057] S1: As Figure 6 As shown, with the splicing center of four adjacent cast-in-place wall panels 28 arranged in a grid pattern as the center, an annular groove 29 is opened on the wall surface, and a conductive thin ring 1 is fixed in the annular groove 29; so that one conductive thin ring 1 can detect four adjacent cast-in-place wall panels 28 at the same time, and when a crack appears at the connection between any two cast-in-place wall panels 28, the conductive thin ring 1 will break due to the displacement caused by the crack.

[0058] S2: The testing agency performs conductivity tests on each of the conductive thin rings 1 on the wall 28. If any conductive thin ring 1 is non-conductive, the corresponding conductive thin ring 1 is reinstalled and the conductivity test is repeated until all conductive thin rings 1 are conductive. The method by which the testing agency performs conductivity tests on each of the conductive thin rings 1 includes:

[0059] S21: The two contact heads 11 on the detection unit 10 are driven by the motion unit 6, the first telescopic mechanism 7, and the second telescopic mechanism 9 to connect sequentially with the two contact points 2 on a plurality of conductive thin rings 1, and the conductivity test of the conductive thin rings 1 is performed by the continuity detection circuit.

[0060] S22: Each time the two contact heads 11 connect with the two contact points 2, the computer module records the amount of motion of the motion unit 6, the first telescopic mechanism 7, and the second telescopic mechanism 9, and summarizes the position coordinates of the detection unit 10 and each conductive thin ring 1, and saves the position coordinates in the computer module.

[0061] S3: After a preset time interval, the conductivity of several conductive thin rings 1 on the wall 28 is tested one by one by the testing mechanism. If there are non-conductive conductive thin rings 1, the position is marked at this point and step S4 is executed. If all conductive thin rings 1 are in a conductive state, step S3 is repeated to continuously and periodically test several conductive thin rings 1.

[0062] The method by which the testing mechanism performs conductivity tests on several conductive thin rings 1 one by one includes: calling the position coordinates in the computer module, controlling the testing unit 10 to automatically move to several position coordinates, and observing the docking of the two contact heads 11 with the two contact points 2 through the camera module 12. If there is a docking deviation, the position of the testing unit 10 is adjusted through the motion unit 6, the first telescopic mechanism 7 and the second telescopic mechanism 9 until the two contact heads 11 are docked with the two contact points 2. Then, the conductivity of the conductive thin rings 1 is tested through the continuity detection circuit.

[0063] S4: Using the location mark as the center, observe the connection between two adjacent cast-in-place walls 28 in all directions until the crack at the connection of the walls 28 is found;

[0064] S5: After repairing and reinforcing the crack, drill holes in the wall 28 on both sides of the crack, and fix the two fixing heads 3 of the crack measuring device into the two drilled holes respectively; the specific method of fixing the fixing heads 3 into the drilled holes includes:

[0065] S51: By pulling a traction rope 23, the two magnetic drive blocks slide in the two sliding grooves 20 respectively, until one of the N-pole magnetic block 24 and S-pole magnetic block 25 of each magnetic drive block aligns with the magnetic block 18 and attracts each other, thereby causing the support head 17 to retract.

[0066] S52: Place the fixing head 3 inside the borehole and pull another traction rope 23 to drive the two magnetic drive blocks to slide in opposite directions in the two sliding grooves 20 until one of the N pole magnetic block 24 and S pole magnetic block 25 of each magnetic drive block is aligned with the magnetic block 18 and repels each other, thereby extending the support head 17 and abutting against the inner wall of the borehole.

[0067] S6: Periodically check the change in the pull wire sensor 4. If the change is zero, reinstall the new conductive thin ring 1 at the position mark, remove the crack measuring device, and return to step S3. If the change is not zero, continue to repair and reinforce the crack until the change in the pull wire sensor 4 is zero.

[0068] After the conductive thin rings 1 are installed, the drive detection unit 10 performs a pre-conductivity test on the conductive thin rings 1 to ensure that each conductive thin ring 1 is in an effective state. Subsequent periodic conductivity tests on the conductive thin rings 1 can be performed automatically using the position coordinates saved during the pre-conductivity test, thus simplifying the subsequent conductivity test operation. At the same time, in order to avoid the contact points 2 on the wall 28 from shifting due to cracks, the automated conductivity test also needs to be combined with the observation of the camera module 12 and the position adjustment of the detection unit 10 to ensure that each time the two contact heads 11 are respectively connected to the two contact points 2.

[0069] Specifically, the conductive thin ring 1 of this solution is made of a brittle metallic material or a brittle non-metallic material, and a conductive coating is applied to the non-metallic material to achieve conductivity. The conductive thin ring 1 has slight toughness, so that when the wall 28 experiences slight vibration or a small crack occurs at the connection of the wall 28, the conductive thin ring 1 will deform slightly without breaking. When the crack width reaches a certain value, the conductive thin ring 1 will break after slight deformation. In addition, the method of repairing and reinforcing the cracks in the wall 28 in this solution adopts existing technology. Therefore, the repair method includes, but is not limited to: injecting mortar, resin, crack repair agent, and leak-proof agent into the crack. The reinforcement method includes, but is not limited to: planting rebar at the crack, adding fixing bolts, and tie bolts.

Claims

1. A system for monitoring cracks in underground space structures, characterized in that, Includes a point detection system for detecting whether there are cracks at the joints of the wall (28) and a crack measuring device for measuring the changes in cracks at the joints of the wall (28); The point detection system includes several conductive thin rings (1) placed at the connection of the wall (28). The conductive thin rings (1) are open-loop structures with notches. The conductive thin rings (1) are provided with contacts (2) at both ends of the notches. The two contacts (2) are located on a single cast wall (28). The point detection system also includes a detection mechanism for detecting whether the two contacts (2) of the several conductive thin rings (1) are conductive. The crack measuring device includes a fixed head (3) fixed on the drilled holes of the wall (28) on both sides of the crack. A pull wire sensor (4) for measuring the distance is provided between the two fixed heads (3). A piston rod (13) and a sleeve (14) are respectively provided on the two fixed heads (3). The piston rod (13) and the sleeve (14) slide and extend in cooperation. A guide wheel (15) is provided at one end of the sleeve (14) near the fixed head (3). The front end of the pull wire (16) in the pull wire sensor (4) is fixed to the front end of the piston rod (13). The pull wire (16) passes around the guide wheel (15) and passes through the rear end of the piston rod (13) and connects to the pull wire sensor (4). An expansion support mechanism for fixed contact with the inner side wall of the drilled hole of the wall (28) is provided on the outer wall of the fixed head (3).

2. The underground space structure crack monitoring system according to claim 1, characterized in that, The detection mechanism includes a crossbar (5) located on one side of the wall (28), a motion unit (6) is slidably arranged on the crossbar (5), the motion unit (6) is connected to the transition unit (8) through a first telescopic mechanism (7), and the motion directions of the motion unit (6) and the transition unit (8) are perpendicular to each other and parallel to the wall (28). The transition unit (8) is connected to the detection unit (10) through a second telescopic mechanism (9), and the extension direction of the second telescopic mechanism (9) is perpendicular to the wall (28).

3. The underground space structure crack monitoring system according to claim 2, characterized in that, The detection unit (10) includes an automatic positioning module and two contact heads (11) that are respectively in contact with two contacts (2) of a plurality of conductive thin rings (1). The two contact heads (11) are electrically connected to the continuity detection circuit. The automatic positioning module includes a camera module (12) and a computer module. The motion unit (6), the first telescopic mechanism (7), the second telescopic mechanism (9), the continuity detection circuit, and the camera module (12) are all electrically connected to the computer module.

4. The underground space structure crack monitoring system according to claim 1, characterized in that, The piston rod (13) and sleeve (14) are respectively hinged to the two fixed heads (3), and the rotating surface at the hinge is perpendicular to the wall (28).

5. The underground space structure crack monitoring system according to claim 1, characterized in that, The expansion mechanism includes support heads (17) arranged on both sides of the fixed head (3). Magnetic blocks (18) and telescopic rods (19) are arranged sequentially on the inner side of the support heads (17). The telescopic rods (19) are arranged radially on the side wall of the fixed head (3). A magnetic mechanism for driving the magnetic blocks (18) to move radially is arranged inside the fixed head (3).

6. The underground space structure crack monitoring system according to claim 5, characterized in that, The fixed head (3) is provided with two sliding grooves (20). The magnetic mechanism includes a magnetic drive block movably disposed in the sliding groove (20). The front ends of the two magnetic drive blocks are connected by a connecting rope (21). The front end of the fixed head (3) is provided with a pulley (22) that cooperates with the connecting rope (21). The rear ends of the two magnetic drive blocks are respectively connected to the front ends of two traction ropes (23). The rear ends of the two traction ropes (23) both pass through the fixed head (3). The magnetic drive block includes an N-pole magnetic block (24) and an S-pole magnetic block (25). The relative positions of the N-pole magnetic block (24) and the S-pole magnetic block (25) in the two magnetic drive blocks are opposite.

7. A crack monitoring method using the underground space structure crack monitoring system according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Using the splicing center of the four adjacent cast wall sections (28) arranged in a grid pattern as the center, open an annular groove (29) on the wall surface and fix the conductive thin ring (1) in the annular groove (29); S2: The testing agency conducts a conductivity test on each of the conductive thin rings (1) on the wall (28). If there is a non-conductive conductive thin ring (1), the conductive thin ring (1) at the corresponding position is reinstalled and the conductivity test is conducted again until all the conductive thin rings (1) are in a conductive state. S3: After a preset time interval, the conductivity test is performed on several conductive thin rings (1) on the wall (28) by the testing agency. If there is a non-conductive conductive thin ring (1), the position is marked and step S4 is executed. If all conductive thin rings (1) are in a conductive state, step S3 is repeated to continuously and periodically test several conductive thin rings (1). S4: Observe the connection between two adjacent cast walls (28) from the center of the location mark until the crack at the connection of the wall (28) is found; S5: After repairing and reinforcing the crack, drill holes in the walls (28) on both sides of the crack and fix the two fixing heads (3) of the crack measuring device in the two holes respectively. S6: Periodically check the change in the pull wire sensor (4). If the change is zero, reinstall a new conductive thin ring (1) at the position mark, remove the crack measuring device, and return to step S3. If the change is not zero, continue to repair and reinforce the crack until the change in the pull wire sensor (4) is zero.

8. The crack monitoring method according to claim 7, characterized in that, The method by which the testing mechanism performs conductivity tests on several conductive thin rings (1) one by one in step S2 includes: S21: The two contact heads (11) on the detection unit (10) are driven by the motion unit (6), the first telescopic mechanism (7), and the second telescopic mechanism (9) to connect with the two contacts (2) on several conductive thin rings (1) in sequence, and the conductivity of the conductive thin rings (1) is tested by the continuity detection circuit. S22: Each time the two contact heads (11) connect with the two contact points (2), the computer module records the amount of motion of the motion unit (6), the first telescopic mechanism (7), and the second telescopic mechanism (9), and summarizes the position coordinates of the detection unit (10) and each conductive thin ring (1), and saves the position coordinates in the computer module; The method for the detection mechanism to perform conductivity tests on several conductive thin rings (1) one by one in step S3 includes: calling the position coordinates in the computer module, controlling the detection unit (10) to move automatically to several position coordinates, and observing the docking of the two contact heads (11) and the two contact points (2) through the camera module (12). If there is a docking deviation, the position of the detection unit (10) is adjusted through the motion unit (6), the first telescopic mechanism (7) and the second telescopic mechanism (9) until the two contact heads (11) are docked with the two contact points (2), and then the conductivity test of the conductive thin rings (1) is performed through the continuity detection circuit.

9. The crack monitoring method according to claim 7, characterized in that, The method for fixing the fixing head (3) inside the borehole in step S5 includes: S51: By pulling a traction rope (23), the two magnetic drive blocks are driven to slide in the two sliding grooves (20) respectively until one of the N-pole magnetic block (24) and S-pole magnetic block (25) of each magnetic drive block aligns with the magnetic block (18) and attracts each other; S52: Place the fixing head (3) inside the borehole and pull another traction rope (23) to drive the two magnetic drive blocks to slide in opposite directions in the two sliding grooves (20) until one of the N-pole magnetic block (24) and S-pole magnetic block (25) of each magnetic drive block aligns with the magnetic block (18) and repels each other.

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