Leakage detection method for underground enclosure wall in non-excavation stage

Abstract

The invention discloses an underground enclosure wall leakage detection method in an unexcavated stage, and the method comprises the steps: forming a plurality of through holes in a pipe body of each inclinometer at preset intervals before the construction of an underground enclosure wall; an inclinometer pipe is used as an injection pipe, and whether a leakage area exists in the underground enclosure wall or not is detected through a high-density electrical method instrument; for the underground enclosure wall with the leakage area, the electrode emitters in all the inclinometer pipes on the underground enclosure wall with the leakage area are taken out; and all the inclinometer pipes in the underground enclosure wall with the leakage area serve as sounding pipes, and the coordinate positions of leakage points of the underground enclosure wall with the leakage area are determined through an integrity testing method. The leakage detection efficiency of the underground enclosure wall can be improved, and the structural strength of the underground enclosure wall is prevented from being weakened.

Description

Technical Field

[0001] The present invention relates to the field of leakage detection in building construction, and particularly to a method for detecting leakage of underground retaining walls in the non-excavation stage. Background Art

[0002] The most common construction quality problem of underground retaining walls is that there are pores locally due to improper concrete pouring, and groundwater leaks from the outside of the foundation pit into the pit after the foundation pit is excavated. The leakage of water will weaken the bearing capacity and stiffness of the underground retaining wall, resulting in an increase in the deformation of the foundation pit support system, which may cause the wall to tilt, the joints to crack or local collapse, seriously threatening the construction safety; if the leakage point expands, it may form piping or quicksand, which will increase the loss of soil on the side wall of the foundation pit and cause the overall failure of the support structure. At present, although a group well dewatering test will be carried out before the foundation pit excavation, it can only determine the approximate planar range of the leakage point, but cannot effectively confirm the specific depth position of the leakage point. The integrity detection technology can accurately obtain the positions of cracks and cavities, but there are also certain limitations.

[0003] First: Many measuring points are time-consuming and laborious. Each diaphragm wall interface needs to be detected as a measurement object, and the focus object lacks pertinence. Each measuring point needs to be measured for a long time, and the entire detection work consumes a lot of time, and it is easy to ignore small cracks due to the decrease in attention.

[0004] Second: Embedding acoustic pipes reduces the structural strength of the diaphragm wall. It is necessary to pre-bind acoustic pipes on the steel reinforcement cage of the underground retaining wall, and this place becomes a weak point in strength. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for detecting leakage of underground retaining walls in the non-excavation stage to solve the problems that the group well dewatering test cannot determine the position of the leakage point and the integrity detection requires independent embedding of acoustic pipes, resulting in poor strength at the embedding position of the diaphragm wall and long detection time.

[0006] To solve the above technical problems, the present invention provides a method for detecting leakage of underground retaining walls in the non-excavation stage, including: Before the construction of the underground retaining wall, a plurality of through holes are arranged at a predetermined interval on the tube body of each inclinometer tube; Using the inclinometer tube as an injection tube, detecting whether there is a leakage area in the underground retaining wall through a high-density resistivity instrument; For the underground retaining wall with a leakage area, taking out the electrode transmitters in each inclinometer tube on the underground retaining wall with the leakage area; using each inclinometer tube in the underground retaining wall with the leakage area as an acoustic pipe, and determining the coordinate position of the leakage point of the underground retaining wall with the leakage area through an integrity test method.

[0007] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, the resistivity imaging instrument includes: Inject conductive liquid into each inclinometer tube of the underground retaining wall after construction until it reaches the mouth of the inclinometer tube, so that the conductive liquid penetrates into the underground retaining wall through the through holes. Suspend the electrode transmitter of the resistivity imaging instrument in each inclinometer tube of the underground retaining wall after construction, so that the electrode transmitter injects current into the ground through the conductive liquid in the inclinometer tube used as an injection tube. Insert multiple electrode sensors of the resistivity imaging instrument into the soil on both sides of the underground retaining wall after construction through metal conductors, so that every two electrode sensors are symmetrically distributed on both sides of the underground retaining wall. Measure the potential difference between each group of electrode sensors, and judge whether there is leakage in the underground retaining wall based on the potential difference between each group of electrode sensors. When there is a potential difference between a certain group of electrode sensors, it is judged that there is leakage in the underground retaining wall at the position of the inclinometer tube near the certain group of electrode sensors; otherwise, it is judged as no leakage; thus, quickly screening whether there is a leakage area in the underground retaining wall.

[0008] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, the conductive liquid is brine.

[0009] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, the through holes of the inclinometer tube at each elevation are multiple and distributed circumferentially along the tube body.

[0010] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, the metal conductor is an iron nail.

[0011] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, when there are potential differences in multiple groups of electrode sensors and the potential differences are within the same range, it is judged that the leakage risk levels of the leakage areas of the underground retaining wall are the same.

[0012] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, when there are potential differences in multiple groups of electrode sensors and the potential differences are not within the same range, it is judged that the leakage risk levels of the leakage areas of the underground retaining wall are different.

[0013] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, when the leakage risk levels are different, it is determined that the leakage area of the underground retaining wall with the larger value of the potential difference is single-sided leakage, which is a leakage risk of category II; it is determined that the leakage area of the underground retaining wall with the smaller value of the potential difference is double-sided leakage, which is a leakage risk of category I.

[0014] Furthermore, for the method for detecting leakage of an underground retaining wall during the non-excavation stage provided by the present invention, the integrity test method includes: In each inclinometer tube within the underground retaining wall in the leakage area, a sonar device is placed, and ultrasonic waves are used to conduct an integrity test on the underground retaining wall to determine the coordinate positions of the leakage points in the leakage area of the underground retaining wall.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for detecting leakage of an underground retaining wall in the non-excavation stage provided by the present invention uses the inclinometer tube as an injection tube, and measures the potential difference between each group of electrode sensors through a high-density resistivity instrument to judge the leakage area of the underground retaining wall, thereby quickly screening the underground retaining walls with leakage areas; then, the inclinometer tube is used again as a sonic logging tube, and the coordinate of the leakage point of the underground retaining wall in the leakage area is accurately positioned through an integrity test method, so as to quickly find the leakage point of the underground retaining wall in the non-excavation stage, saving detection time compared with the global use of integrity testing and improving the detection efficiency.

[0016] The method for detecting leakage of an underground retaining wall in the non-excavation stage provided by the present invention, when quickly detecting whether there is a leakage area in the underground retaining wall, uses the inclinometer tube as an injection tube, and there is no need to independently bury an injection tube of a high-density resistivity instrument in the underground retaining wall; when accurately positioning the underground retaining wall in the leakage area, the inclinometer tube is used as a sonic logging tube, and there is no need to bury a large number of sonic logging tubes in the underground retaining wall, so that the inclinometer tube can be used for three purposes, avoiding the problem that the structural strength of the underground retaining wall at the buried node becomes weak due to the burial of a large number of pipes in the underground retaining wall, and avoiding the injection tube and sonic logging tube buried in the underground retaining wall 1, thereby improving the overall strength of the underground retaining wall. Description of the Drawings

[0017] Figure 1 is a flowchart of the method for detecting leakage of an underground retaining wall in the non-excavation stage; Figure 2 is a schematic plan structure diagram of the layout relationship of the high-density resistivity instrument in the method for detecting leakage of an underground retaining wall in the non-excavation stage; Figure 3 is a schematic elevation structure diagram of the connection structure between the electrode sensor and the soil body in the method for detecting leakage of an underground retaining wall in the non-excavation stage; As shown in the figure: 1. Underground retaining wall, 2. Inclinometer tube, 3. Electrode transmitter, 4. Electrode sensor, 5. Metal conductor, 6. Soil body. Detailed Embodiment

[0018] The present invention will be described in detail below with reference to the drawings: According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0019] Please refer to Figures 1 to 3 , an embodiment of the present invention provides a method for detecting leakage of an underground retaining wall in the non-excavation stage, which may include the following steps: Step S100, before the construction of the underground retaining wall 1, a plurality of through holes are provided on the tube body of each inclinometer tube 2 at a predetermined interval. The number of through holes can be adjusted according to the depth of the underground retaining wall 1, such as 6, 10, etc.

[0020] Step S200, using the inclinometer tube 2 as an injection tube, detecting whether there is leakage of the underground retaining wall 1 at each inclinometer tube 2 through a high-density electrical resistivity instrument. Specifically, it includes: Step S210, injecting a conductive liquid such as brine into each inclinometer tube 2 of the constructed underground retaining wall 1 to the mouth of the inclinometer tube 2, so that the conductive liquid penetrates into the underground retaining wall 1 through the through holes. Suspend the electrode emitter 3 of the high-density electrical resistivity instrument in each inclinometer tube 2 of the constructed underground retaining wall 1, so that the electrode emitter 3 injects current into the ground through the conductive liquid in the inclinometer tube 2 as an injection tube. Insert a plurality of electrode sensors 4 of the high-density electrical resistivity instrument into the soil on both sides of the constructed underground retaining wall 1 through a metal conductor 5, so that every two electrode sensors 4 are symmetrically distributed on both sides of the underground retaining wall 1. The metal conductor 5 can be an iron nail, a screw, a copper column, etc.

[0021] Step S220, measure the potential difference, that is, the voltage, between each group of electrode sensors 4, and judge whether there is leakage of the underground retaining wall 1 at each inclinometer tube 2 through the potential difference between each group of electrode sensors 4; when there is a potential difference between a certain group of electrode sensors 4, it is judged that there is leakage of the underground retaining wall 1 at the inclinometer tube 2 near the certain group of electrode sensors 4, otherwise it is judged as non-leakage; thus, determine whether there is a leakage area of the underground retaining wall 1 through the position of the inclinometer tube 2 for rapid screening and judgment, that is, screen whether there is a leakage area of the underground retaining wall 1 in the section where each inclinometer tube 2 is located through the high-density electrical resistivity instrument.

[0022] Among them, the principle for judging the leakage of the underground retaining wall 1 is as follows: when there is leakage in the underground retaining wall 1, the conductive liquid penetrates through the through-hole of the inclinometer tube 2 into the soil mass 6 on at least one side of the underground retaining wall 1 where it is located. Then, an electric field is formed between the electrode transmitter 3 and the electrode sensor 4 through the conductive liquid. There is a potential difference between the two electrode sensors 4 in each group corresponding to the inclinometer tube 2 with leakage, and thus it is judged whether there is a leakage area in the underground retaining wall 1. Specifically, before and after the conductive liquid leaks in at least one side of the soil mass 6 on both sides of the underground retaining wall 1, the sectional resistivity of the underground medium across the underground retaining wall 1 between the electrode sensors 4 in each group is different. Since the conductive liquid penetrates through the through-hole of the inclinometer tube 2 into the soil mass 6 on at least one side of the underground retaining wall 1 where it is located, an electric field is formed between the electrode transmitter 3 and the electrode sensor 4 through the conductive liquid. Then, the conductive liquid forms a current path between the electrode sensors 4 in each group, and a potential difference is generated between the electrode sensors 4 in the corresponding group. When there is no leakage in the underground retaining wall 1, the conductive liquid does not penetrate through the underground retaining wall 1 and leak into the soil masses 6 on both sides of it. Therefore, no potential difference is generated between the electrode sensors 4 in each group. Among them, when there is leakage in the underground retaining wall 1, the sectional resistivity of the underground medium across the underground retaining wall 1 between the electrode sensors 4 in each group can be calculated according to formula (1): ρ = K×ΔV / I (1); In formula (1), ρ is the sectional resistivity, K is the geometric coefficient, ΔV is the potential difference, and I is the injected current.

[0023] That is to say, the essence of the leakage principle of the underground retaining wall 1 is to judge the sectional resistivity of the underground medium across the underground retaining wall 1 between the electrode sensors 4 in each group.

[0024] Among them, the leakage principle of the underground retaining wall 1 can also be simply judged by the dropping speed of the conductive liquid in the inclinometer tube 2. When the inclinometer tube 2 is filled with the conductive liquid and no continuous injection is carried out, when there is leakage in the underground retaining wall 1, the conductive liquid in the inclinometer tube 2 will drop rapidly, while when there is no leakage in the underground retaining wall 1, the conductive liquid in the corresponding inclinometer tube 2 will not drop rapidly. At this time, it can be preliminarily judged whether there is a leakage area in the underground retaining wall 1 at the location of the inclinometer tube 2 by the dropping speed of the conductive liquid filled in the inclinometer tube 2.

[0025] Step S300: For the underground retaining wall 1 with a leakage area, take out the electrode transmitters 3 in each inclinometer tube 2 on the underground retaining wall 1 with the leakage area, use each inclinometer tube 2 in the underground retaining wall 1 with the leakage area as a sonic logging tube, and determine the coordinate position of the leakage point of the underground retaining wall 1 in the leakage area through an integrity test method. Specifically, it can be: put a sonar device into each inclinometer tube 2 in the underground retaining wall 1 with the leakage area and perform an integrity test on the underground retaining wall 1 through ultrasonic waves to determine the coordinate position of the leakage point of the underground retaining wall 1 in the leakage area. The specific coordinate position where cracks or cavities occur in the underground retaining wall 1 can be detected through the sonar device. The sonar device can include an ultrasonic testing device or a sonar tube containing an ultrasonic testing device.

[0026] The method for detecting leakage of an underground retaining wall in the non-excavation stage provided by the embodiment of the present invention uses the inclinometer tube 2 as an injection tube, measures the potential difference between each group of electrode sensors 4 through a high-density resistivity instrument to judge the leakage area of the underground retaining wall 1, so as to quickly screen the underground retaining wall 1 with a leakage area; then uses the inclinometer tube 2 as a sonic logging tube again, and accurately locates the coordinates of the leakage points of the underground retaining wall 1 with a leakage area through an integrity test method, so as to quickly find the leakage points of the underground retaining wall 1 in the non-excavation stage, saving detection time compared with globally using the integrity test and improving the detection efficiency.

[0027] The method for detecting leakage of an underground retaining wall in the non-excavation stage provided by the embodiment of the present invention, when quickly detecting whether there is a leakage area in the underground retaining wall 1, uses the inclinometer tube 2 as an injection tube without independently burying an injection tube of a high-density resistivity instrument in the underground retaining wall 1; when accurately positioning the underground retaining wall 1 with a leakage area, uses the inclinometer tube 2 as a sonic logging tube without burying a large number of sonic logging tubes in the underground retaining wall 1, so that the inclinometer tube 2 can be used for three purposes, avoiding the problem that the structural strength of the underground retaining wall 1 at the joints where a large number of pipes are buried in the underground retaining wall 1 becomes weak, and avoiding the injection tubes and sonic logging tubes buried in the underground retaining wall 1, thereby improving the overall strength of the underground retaining wall 1. The original function of the inclinometer tube 2 is to measure the verticality of the underground retaining wall 1 during the construction of the underground retaining wall 1.

[0028] In order to judge the leakage conditions on both sides of the underground retaining wall 1, for the method for detecting leakage of an underground retaining wall in the non-excavation stage provided by the embodiment of the present invention, the through holes of the inclinometer tube 2 at each elevation are distributed in a plurality along the circumferential direction of its tube body.

[0029] In order to evaluate the size of the leakage area when there is leakage in the underground retaining wall 1, for the underground retaining wall leakage detection method in the non-excavation stage provided by the embodiments of the present invention, when there are potential differences in multiple groups of electrode sensors 4 and the potential differences are within the same range, it is determined that the leakage risk levels of the leakage areas of the underground retaining wall 1 are the same. When there are potential differences in multiple groups of electrode sensors 4 and the potential differences are not within the same range, it is determined that the leakage risk levels of the leakage areas of the underground retaining wall 1 are different. When the leakage risk levels are different, it is determined that the leakage area of the underground retaining wall 1 with the larger value of the potential difference is unilateral leakage, which is a leakage risk of category two; it is determined that the leakage area of the underground retaining wall 1 with the smaller value of the potential difference is bilateral leakage, which is a leakage risk of category one. When there is no leakage area, it is a leakage risk of category three. Among them, the level of the leakage risk of category one is greater than that of category two, and the level of the leakage risk of category two is greater than that of category three. When there is no leakage area, when setting the reason for the leakage risk of category three, there may be potential leakage hazards in the later stage.

[0030] The present invention is not limited to the above specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention. Those skilled in the art can make other levels of modifications and changes to the present invention. Thus, if these modifications and changes of the present invention are within the scope of the claims of the present invention, the present invention also intends to include these modifications and changes.

Claims

1. A method for detecting leakage of underground retaining walls in the unexcavated stage, characterized in that: include: Before the construction of the underground retaining wall, a plurality of through holes are arranged at predetermined intervals on the pipe body of each inclinometer pipe; Using the inclinometer tube as the injection tube, a high-density electrical instrument is used to detect whether there is a leakage area in the underground retaining wall; For underground retaining walls in the leakage area, the electrode transmitters in each inclinometer tube on the underground retaining wall in the leakage area are taken out; each inclinometer tube in the underground retaining wall in the leakage area is used as an acoustic detection tube, and the coordinate position of the leakage point of the underground retaining wall in the leakage area is determined by the integrity test method.

2. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 1, characterized in that: The high-density electrical method instrument comprises: Injecting conductive liquid into each inclinometer tube of the constructed underground retaining wall to the tube opening of the inclinometer tube, so that the conductive liquid penetrates into the underground retaining wall through the through hole; The electrode transmitter of the high-density electrical method instrument is suspended in each inclinometer tube of the underground retaining wall after construction, so that the electrode transmitter injects current into the ground through the conductive liquid in the inclinometer tube as an injection pipe, and multiple electrode sensors of the high-density electrical method instrument are inserted into the soil on both sides of the underground retaining wall after construction through metal conductors, so that every two electrode sensors form a group and are symmetrically distributed on both sides of the underground retaining wall; The potential difference between each group of electrode sensors is measured, and whether there is leakage in the underground retaining wall is determined by the potential difference between each group of electrode sensors. When there is a potential difference between a certain group of electrode sensors, it is determined that there is leakage in the underground retaining wall at the inclinometer tube near the certain group of electrode sensors, otherwise, it is determined that there is no leakage; thereby quickly screening whether there is a leakage area in the underground retaining wall.

3. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 2, characterized in that: The conductive liquid is salt water.

4. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 2, characterized in that: The inclinometer tube has a plurality of through holes at each elevation distributed along the circumference of the tube body.

5. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 2, characterized in that: The metal conductor is an iron nail.

6. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 2, characterized in that: When there are potential differences in the plurality of groups of electrode sensors and the potential differences are within the same range, it is determined that the leakage risk levels of the leakage areas of the underground retaining wall are the same.

7. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 2, characterized in that: When there are potential differences in multiple groups of electrode sensors and the potential differences are not within the same range, it is determined that the leakage risk levels of the leakage areas of the underground retaining wall are different.

8. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 7, characterized in that: When the leakage risk levels are different, the leakage area of ​​the underground retaining wall with a larger potential difference is judged as single-sided leakage, which is a second-class leakage risk; the leakage area of ​​the underground retaining wall with a smaller potential difference is judged as double-sided leakage, which is a first-class leakage risk.

9. The method for detecting leakage of underground retaining walls in the unexcavated stage according to claim 1, characterized in that: The integrity testing method comprises: Sonar equipment is placed in each inclinometer tube in the underground retaining wall in the leakage area to conduct an integrity test of the underground retaining wall through ultrasonic waves to determine the coordinate position of the leakage point of the underground retaining wall in the leakage area.

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