Nondestructive detection device and method for foundation pit support leakage based on conductivity increase and decrease

Abstract

The invention discloses a nondestructive detection device and method for leakage of a foundation pit support based on conductance increase and decrease, and aims to solve the problems of limited quantitative analysis capability, reduced resolution and certain destructiveness of an existing foundation pit support leakage detection technology. The bottom end of the outer pipe is closed, and a through hole is formed in the side wall of the outer pipe; the inner pipe is sleeved with the outer pipe; the conductive rod is arranged in an inner cavity of the inner pipe along the axis; the sand filling layer is arranged in the inner cavity of the inner pipe; the method comprises the following steps: pre-burying a detection device at an underground foundation pit support seam; taking out an inner pipe within 24 hours after initial setting of concrete at the seam; carrying out electric pulse monitoring on a conductive rod at regular intervals; collecting initial values of conductive sections of the conductive rod by a control terminal, carrying out electric pulse monitoring on the conductive rod at regular intervals, reducing resistance at corresponding positions of the conductive rod and generating a reflection signal; and establishing a database of time and amplitude of the reflected signals, and comparing monitoring results of each time to obtain an initial leakage position of the foundation pit support.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction monitoring, and particularly to a non-destructive detection device and method for leakage of foundation pit retaining structures based on the increase and decrease of conductivity. Background Art

[0002] With the continuous deepening of urban underground space development, the scale of foundation pit projects is increasing day by day, the structural complexity is rising, and the leakage risk is also increasing. Leakage will not only weaken the stability of the foundation pit retaining structure, but may also lead to the collapse of the surrounding soil, the loss of groundwater, and damage to the surrounding environment, and even endanger the safety of construction workers and the quality of the project.

[0003] The existing detection technologies for leakage of foundation pit retaining structures mainly include ultrasonic detection, ground penetrating radar detection, osmotic water test, etc. Ultrasonic detection judges the leakage position by analyzing the propagation characteristics of sound waves in the medium, and its ability to quantitatively analyze defects is limited; although ground penetrating radar detection can quickly detect underground structures, the signal interference is large and the resolution is reduced under complex geological conditions; although the osmotic water test is intuitive, the operation is cumbersome and it has a certain destructive effect on underground structures. The above detection technologies have limitations in actual construction sites and are difficult to meet the increasingly strict engineering safety and quality requirements. Therefore, it is urgent to develop more efficient, accurate and non-destructive leakage detection technologies to ensure the safe construction and long-term stability of foundation pit projects. Summary of the Invention

[0004] Aiming at the problems of limited quantitative analysis ability, reduced resolution and certain destructiveness of the existing detection technologies for leakage of foundation pit retaining structures, the purpose of the present invention is to provide a non-destructive detection device and method for leakage of foundation pit retaining structures based on the increase and decrease of conductivity.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a non-destructive detection device for leakage of foundation pit retaining structures based on the increase and decrease of conductivity, which includes: an outer pipe, an inner pipe, a conductive rod, a filling sand layer and a control terminal. The top of the outer pipe is open, the bottom of the outer pipe is provided with a closed bottom plate, and the side wall of the outer pipe is provided with a plurality of through holes. The inner pipe is in a through cylindrical shape and is sleeved inside the outer pipe. There are no through holes on the side wall of the inner pipe. The conductive rod is arranged along the axis of the inner pipe in its inner cavity. Sand is filled between the inner pipe and the conductive rod to form a filling sand layer. The conductive rod is signal-connected to the control terminal.

[0006] The present invention discloses a nondestructive detection device for foundation pit enclosure leakage based on conductivity increase and decrease, which comprises an outer tube with a closed bottom and a through hole in the side wall, an inner tube sleeved inside the outer tube, a conductive rod arranged in the inner cavity of the inner tube along the axis, a filling sand layer arranged in the inner cavity of the inner tube, and a control terminal connected to the conductive rod signal. During the pouring of concrete at the foundation pit enclosure joint, the inner tube is used to isolate and protect the conductive rod to prevent water in the concrete from penetrating into the inner tube. The inner tube is taken out within 24 hours after the initial setting of the concrete. When there is water leakage at the joint, the water leakage penetrates through the through hole of the outer tube and the filling sand layer to the conductive rod. The construction personnel regularly perform electric pulse monitoring on the conductive rod. The conductive rod has a high resistance in a dry state, but after it contacts water, water molecules will fill the conductive rod. The gaps between the polymer chains are opened, the ion transmission path is enhanced, the resistance of the corresponding position of the conductive rod is reduced and a reflected signal is generated. A database of the time and amplitude of the reflected signal is established and compared with the monitoring results of each time. The position of the resistance change can be accurately located, and the initial position of the foundation pit retaining wall leakage can be obtained. If a leakage of a longer length or at more points occurs, it is determined whether the original leakage point is serious and spreads, or a new leakage point has appeared; the control terminal is used to receive the electric pulse reflection characteristics of the conductive rod to detect the leakage point, and there is no signal interference at the construction site, which improves the accuracy of the detection result; moreover, the detection device has a simple structure and is easy to operate, and will not cause damage to the foundation pit retaining structure, thereby realizing non-destructive detection of underground foundation pit retaining leakage points.

[0007] Furthermore, the conductive rod includes a plurality of conductive segments arranged along the axis, and an insulating layer arranged between two adjacent conductive segments, and each conductive segment is connected to the control terminal signal.

[0008] Furthermore, a corresponding locking structure is provided between the outer wall of the inner tube and the inner wall of the outer tube, so that the inner tube is embedded in the outer tube and is locked and connected thereto.

[0009] Furthermore, the conductive rod is made of conductive polymer.

[0010] Furthermore, the top of the conductive rod is at least 10 cm higher than the top of the foundation pit enclosure.

[0011] In addition, the present invention also provides a nondestructive detection method for foundation pit enclosure leakage based on conductivity increase and decrease, using the nondestructive detection device for foundation pit enclosure leakage based on conductivity increase and decrease, the steps are as follows: S1: Pre-buried foundation pit retaining leakage non-destructive detection device at the joint of underground foundation pit retaining, the top of the outer pipe and the inner pipe are flush with the top of the foundation pit retaining, and the inner pipe is removed within 24 hours after the concrete at the joint of the foundation pit retaining is initially set; S2: After the conductive rod stabilizes, send an electrical pulse to the conductive rod. The control terminal collects the initial values of each conductive segment of the conductive rod and regularly monitors the conductive rod with electrical pulses; when there is water leakage at the joint, regularly monitor the conductive rod with electrical pulses. The resistance at the corresponding position of the conductive rod decreases and a reflection signal is generated. Establish a database of the time and amplitude of the reflection signal and compare the monitoring results each time to be able to locate the position where the resistance changes and obtain the initial position of the leakage of the foundation pit enclosure.

[0012] The non-destructive detection method for leakage of foundation pit enclosures based on the increase and decrease of conductivity of the present invention pre-buries a non-destructive detection device for leakage of foundation pit enclosures at the joints of underground foundation pit enclosures. Remove the inner tube within 24 hours after the concrete at the joints of the foundation pit enclosures begins to set. Regularly monitor the conductive rod with electrical pulses. The control terminal collects the initial values of each conductive segment of the conductive rod. When there is water leakage at the joint, the water leakage penetrates through the through holes of the outer tube and the filling sand layer and seeps to the conductive rod. The construction personnel regularly monitor the conductive rod with electrical pulses. The resistance at the corresponding position of the conductive rod decreases and a reflection signal is generated. Establish a database of the time and amplitude of the reflection signal and compare the monitoring results each time to be able to accurately locate the position where the resistance changes and obtain the initial position of the leakage of the foundation pit enclosures. If there is leakage at a greater length or more positions, determine whether the original leakage point is serious and spreading or new leakage points have appeared; by pre-burying the detection device at the joints of the foundation pit enclosures and using the performance attenuation of the conductive rod after later water seepage, thus dynamically and accurately judging the position of the leakage point of the foundation pit and the leakage diffusion range, so as to solve the problems that it is difficult to accurately determine the position of the leakage detection of the underground foundation pit enclosures and the development of the leakage points cannot be evaluated, and the function of in-situ non-destructive leakage detection of the retaining wall at the construction site can be realized.

[0013] Further, step S2 further includes: The conductive rod includes a plurality of conductive segments arranged along the axis and insulating layers provided between adjacent two conductive segments. The plurality of conductive segments are pre-numbered, and each conductive segment is signal-connected to the control terminal; when water seeps at the joint, the resistance of the corresponding conductive segment decreases and a reflection signal is generated. The control terminal receives the time and amplitude of the reflection signal to locate the longitudinal position of the corresponding numbered conductive segment where the resistance changes. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the non-destructive detection device for leakage of foundation pit enclosures based on the increase and decrease of conductivity of the present invention; Figure 2 It is a schematic diagram of the conductive rod and the filling sand layer in the non-destructive detection device for leakage of foundation pit enclosures in an embodiment of the present invention; Figure 3 It is a top view of the non-destructive detection device for leakage of foundation pit enclosures in an embodiment of the present invention; Figure 4Schematic diagram of the connection between multiple conductive segments and a control terminal in a non-destructive detection device for leakage in a foundation pit retaining structure according to an embodiment of the present invention; Figure 5 Schematic diagram of an embodiment of a non-destructive detection method for leakage in a foundation pit retaining structure based on conductance increase and decrease according to the present invention. The reference numerals in the figure are as follows: Non-destructive detection device 10 for leakage in a foundation pit retaining structure; outer pipe 1; through hole 1a; inner pipe 2; locking structure 3; conductive rod 5; conductive segment 51; insulating layer 52; sand filling layer 6; foundation pit retaining structure 20; electric pulse emitting device 30. Detailed implementation manners

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. For the sake of description convenience, the "upper" and "lower" directions mentioned hereinafter are consistent with the upper and lower directions of the accompanying drawings, but this cannot be a limitation to the technical solution of the present invention.

[0016] Combined with Figures 1 to 5 The non-destructive detection device 10 for leakage in a foundation pit retaining structure based on conductance increase and decrease according to the present invention will be described. It includes: an outer pipe 1, an inner pipe 2, a conductive rod 5, a sand filling layer 6 and a control terminal (not shown in the figure). The top of the cylindrical outer pipe 1 is open, and its bottom end is provided with a closed bottom plate. A plurality of circular through holes 1a are uniformly and densely distributed on the side wall of the outer pipe 1. The inner pipe 2 is a through cylindrical shape. The inner pipe 2 is closely sleeved inside the outer pipe 1. There are no through holes on the side wall of the inner pipe 2. The conductive rod 5 is arranged along the axis of the inner pipe 2 in its inner cavity. Sand is filled between the inner pipe 2 and the conductive rod 5 to form a sand filling layer 6. The conductive rod 5 is signal-connected to the control terminal.

[0017] The non-destructive detection device 10 for leakage of foundation pit enclosure based on conductance increase and decrease of the present invention includes an outer tube 1 with a closed bottom end and through holes 1a provided on the side wall, an inner tube 2 sleeved inside the outer tube 1, a conductive rod 5 arranged along the axis in the inner cavity of the inner tube 2, a filling sand layer 6 arranged in the inner cavity of the inner tube 2, and a control terminal signal-connected to the conductive rod 5. During the concrete pouring process at the joint 20 of the foundation pit enclosure, the inner tube 2 is used to isolate and protect the conductive rod 5 to prevent water in the concrete from seeping into the inside of the inner tube 2. The inner tube 2 is taken out within 24 hours after the concrete initial setting. When there is water leakage at the joint, the water leakage penetrates through the through holes 1a of the outer tube 1 and the filling sand layer 6 and permeates to the conductive rod 5. The construction personnel regularly monitor the conductive rod 5 for electrical pulses. The conductive rod 5 has a relatively high resistance in a dry state, but after it contacts water, water molecules will fill the gaps between the polymer chains of the conductive rod 5, enhancing the ion transmission path, resulting in a decrease in the resistance at the corresponding position of the conductive rod 5 and generating a reflection signal. By establishing a database of the time and amplitude of the reflection signal and comparing the monitoring results each time, the position where the resistance changes can be accurately located, and the initial position of the leakage of the foundation pit enclosure 20 can be obtained. If there is leakage at a greater length or more points, it can be judged whether the original leakage point is serious and spreading, or whether a new leakage point has appeared; the control terminal is used to receive the electrical pulse reflection characteristics of the conductive rod 5 to detect the leakage point, and there is no signal interference at the construction site, improving the accuracy of the detection result; moreover, the detection device has a simple structure and is convenient to operate, and will not cause damage to the structure of the foundation pit enclosure 20, realizing the non-destructive detection of the leakage point of the underground foundation pit enclosure 20.

[0018] As Figure 4 shown, the conductive rod 5 includes a plurality of conductive segments 51 arranged along the axis and an insulating layer 52 arranged between adjacent two conductive segments 51. Each conductive segment 51 is signal-connected to the control terminal. The plurality of conductive segments 51 are pre-numbered. Since each conductive segment 51 is signal-connected to the control terminal, the plurality of conductive segments 51 are in a parallel connection relationship. When one or several conductive segments 51 contact water leakage and cause a change in resistance, the control terminal can accurately judge the longitudinal position where the leakage point is located by receiving the electrical pulse reflection signal of the corresponding conductive segment 51. In this embodiment, a conductive segment 51 is arranged every 50 cm from the bottom of the inner tube 2, and the plurality of conductive segments 51 are connected in parallel with each other.

[0019] As Figure 3 shown, a corresponding locking structure 3 is provided between the outer wall of the inner tube 2 and the inner wall of the outer tube 1, so that the inner tube 2 is embedded in the outer tube 1 and locked with it, improving the connection stability between the two. The specific structure and connection relationship of the locking structure 3 are prior art and will not be elaborated here.

[0020] The conductive rod 5 is made of a conductive polymer, such as polypyrrole, polyaniline, etc., but is not limited thereto.

[0021] The top of the conductive rod 5 is at least 10 cm higher than the top of the foundation pit enclosure 20 to avoid being covered by the concrete poured outside the outer tube 1.

[0022] Combine the following Figures 1 to 5 The nondestructive detection method for foundation pit enclosure leakage based on conductivity increase and decrease of the present invention is described, and the specific steps are as follows: S1: Figure 5 As shown, a nondestructive detection device 10 for foundation pit enclosure leakage is pre-buried at the joint of the underground foundation pit enclosure 20, the top of the outer pipe 1 and the inner pipe 2 are flush with the top of the foundation pit enclosure 20, the inner pipe 2 is taken out within 24 hours after the initial setting of the concrete at the joint of the foundation pit enclosure 20, and some sand is added between the outer pipe 1 and the inner pipe 2 according to the actual situation to ensure that the filling sand layer 6 is dense; S2: After the conductive rod 5 is stable, the electric pulse transmitting device 30 sends electric pulses to the conductive rod 5, and the control terminal collects the initial values ​​of each conductive segment 51 of the conductive rod 5, and regularly performs electric pulse monitoring on the conductive rod 5; when there is water leakage at the joint, the leakage water penetrates through the through hole 1a of the outer tube 1 and the filling sand layer 6 to the conductive rod 5, and the construction personnel regularly perform electric pulse monitoring on the conductive rod 5, and the resistance of the corresponding position of the conductive rod 5 is reduced and a reflection signal is generated. A database of the time and amplitude of the reflection signal is established and compared with each monitoring result, so as to accurately locate the position of the resistance change and obtain the initial position of the leakage of the foundation pit enclosure 20. If there is leakage of a larger length or more points, it is determined whether the original leakage point is serious and spreads, or a new leakage point has appeared.

[0023] The nondestructive detection method for foundation pit enclosure leakage based on conductivity increase and decrease of the present invention is as follows: a foundation pit enclosure leakage nondestructive detection device 10 is pre-buried at the joint of the underground foundation pit enclosure 20; the inner tube 2 is taken out within 24 hours after the initial setting of the concrete at the joint of the foundation pit enclosure 20; the conductive rod 5 is regularly monitored by electric pulses; the control terminal collects the initial values ​​of each conductive segment 51 of the conductive rod 5; when there is leakage water at the joint, the leakage water penetrates through the through hole 1a of the outer tube 1 and the filling sand layer 6 to the conductive rod 5; the construction personnel regularly monitor the conductive rod 5 by electric pulses; the resistance of the corresponding position of the conductive rod 5 is reduced and a reflection signal is generated; and data of the time and amplitude of the reflection signal are established. By comparing the monitoring results of each time, the position of the resistance change can be accurately located, and the initial position of the leakage of the foundation pit retaining wall 20 can be obtained. If leakage occurs in a larger length or at more locations, it can be determined whether the original leakage point is serious and has spread, or a new leakage point has appeared. By burying the detection device in advance at the joints of the foundation pit retaining wall 20, the performance attenuation of the conductive rod 5 after the later water seepage is used to dynamically and accurately determine the position of the foundation pit leakage point and the leakage diffusion range, thereby solving the problem that the position of the underground foundation pit retaining wall 20 leakage detection is difficult to accurately determine and the development of the leakage point cannot be evaluated, and the function of in-situ non-destructive leakage detection of the retaining wall at the construction site can be realized.

[0024] The step S2 further includes: the conductive rod 5 includes a plurality of conductive segments 51 arranged along the axis, and insulating layers 52 disposed between adjacent two conductive segments 51. The plurality of conductive segments 51 are pre-numbered, and each conductive segment 51 is signal-connected to the control terminal. When water seeps at the joint, the seepage water passes through the through hole 1a of the outer pipe 1 and the filling sand layer 6 and penetrates into the conductive segment 51, resulting in a decrease in the resistance of the corresponding conductive segment 51 and generating a reflection signal. The control terminal receives the time and amplitude of the reflection signal to locate the longitudinal position of the corresponding numbered conductive segment 51 where the resistance changes, so as to accurately obtain the depth of the leakage point and the leakage diffusion range.

[0025] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosure fall within the scope of the claims.

Claims

1. A non-destructive detection device for leakage of foundation pit enclosure based on the increase and decrease of conductivity, characterized in that, It includes: An outer tube, an inner tube, a conductive rod, a filling sand layer and a control terminal. The outer tube is open at the top and has a closed bottom plate at the bottom. The outer tube side wall is provided with multiple through holes. The inner tube is in a through cylindrical shape. The inner tube is sleeved in the outer tube. The inner tube side wall has no through holes. The conductive rod is arranged in the inner cavity of the inner tube along the axis. Sand is filled between the inner tube and the conductive rod to form a filling sand layer. The conductive rod is connected to the control terminal signal.

2. The non-destructive detection device for leakage of foundation pit enclosure based on increase and decrease of conductivity according to claim 1, characterized in that: The conductive rod comprises a plurality of conductive segments arranged along an axis, and an insulating layer arranged between two adjacent conductive segments, and each conductive segment is connected to a control terminal signal.

3. The non-destructive detection device for leakage of foundation pit enclosure based on conductance increase and decrease according to claim 1, characterized in that: A corresponding locking structure is provided between the outer wall of the inner tube and the inner wall of the outer tube, so that the inner tube is embedded in the outer tube and is locked and connected thereto.

4. The non-destructive detection device for leakage of foundation pit enclosure based on conductance increase and decrease according to claim 1, characterized in that: The conductive rod is made of conductive polymer.

5. The non-destructive detection device for leakage of foundation pit enclosure based on conductance increase and decrease according to claim 1, wherein: The top of the conductive rod is at least 10 cm higher than the top of the foundation pit enclosure.

6. A method for nondestructive detection of foundation pit enclosure leakage based on conductivity increase and decrease, using the nondestructive detection device for foundation pit enclosure leakage based on conductivity increase and decrease as claimed in any one of claims 1 to 5, characterized in that: S1: Pre-buried foundation pit retaining leakage non-destructive detection device at the joint of underground foundation pit retaining, the top of the outer pipe and the inner pipe are flush with the top of the foundation pit retaining, and the inner pipe is removed within 24 hours after the concrete at the joint of the foundation pit retaining is initially set; S2: After the conductive rod is stable, an electric pulse is sent to the conductive rod, and the control terminal collects the initial values ​​of each conductive segment of the conductive rod, and the conductive rod is regularly monitored by electric pulses; when there is water leakage at the joint, the conductive rod is regularly monitored by electric pulses, the resistance at the corresponding position of the conductive rod is reduced and a reflected signal is generated, a database of the time and amplitude of the reflected signal is established and compared with each monitoring result, the position of the resistance change can be located, and the initial position of the foundation pit retaining wall leakage can be obtained.

7. The non-destructive detection method for leakage of foundation pit retaining based on the increase and decrease of conductance according to claim 6, characterized in that, The step S2 also includes: the conductive rod includes a plurality of conductive segments arranged along the axis, and an insulating layer arranged between two adjacent conductive segments, the plurality of conductive segments are numbered in advance, and each conductive segment is connected to the control terminal signal; when water seeps at the joint, the resistance of the corresponding conductive segment decreases and generates a reflection signal, the control terminal receives the time and amplitude of the reflection signal, and locates the longitudinal position of the corresponding numbered conductive segment where the resistance changes.

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