1. A rock-concrete structural body stability monitoring and early warning method based on static magnetic field detection is characterized by comprising the following steps:

preparing a magnetic concrete test piece by using concrete and a magnetic material;

excavating a cavity which is matched with the test piece and used for accommodating the test piece on the rock-concrete structure body to be monitored;

fixing a magnetic field sensor at a preset distance right in front of the cavity, and testing the magnetic field intensity H of the current environment₀；

Placing the test piece into the cavity;

testing the magnetic field intensity of the test piece in the cavity by using the magnetic field sensor until the data of the magnetic field sensor is stable, and reading the initial magnetic field intensity H of the test piece in the cavity₁；

Periodically testing the magnetic field intensity H of the test piece in the compression deformation process according to a preset period_t；

Based on the change rate of the magnetic field intensity of the test piece, judging the stability of the rock-concrete structure body to be monitored according to a preset judgment criterion, and realizing the monitoring and early warning of the stability of the rock-concrete structure body to be monitored; wherein the preset criterion is as follows: the rate of change of magnetic field strength of the test piece, mu ═ H_t－H₁)/(H₁－H₀) The larger the size, the more unstable the rock-concrete structure, and when μ is equal to or greater than a set threshold value, the rock-concrete structure is at risk of instability.

2. The method for monitoring and early warning the stability of the rock-concrete structural body based on the static magnetic field detection as claimed in claim 1, wherein the step of preparing the magnetic concrete test piece by using the concrete and the magnetic material comprises the following steps:

mixing the concrete and the magnetic material according to the mass ratio of 5:1, and uniformly stirring by using a vibrating rod;

placing the mixed material of the concrete and the magnetic material into a mould, adding water, pouring, forming and curing;

and taking out the cured concrete block from the mold, cutting a sample from the middle part of the concrete block by using a cutting machine, and polishing the sample into a cuboid test piece with a smooth outer surface by using a polishing machine.

3. The static magnetic field detection-based rock-concrete structure stability monitoring and early warning method as claimed in claim 2, wherein the concrete is the concrete with the designation C80; the magnetic material is iron-nickel alloy particles with the diameter of 1 mm; the volume of the mould is 20cm³The above; the mixed material of the concrete and the magnetic material is put into a mould, poured and molded by adding water, and maintained for more than 28 days.

4. A rock-concrete structure stability monitoring and early warning method based on static magnetic field detection as claimed in claim 3, characterized in that the size of the cuboid test piece is 10mm x 5 mm.

5. A rock-concrete structure stability monitoring and early warning method based on static magnetic field detection as claimed in claim 4, characterized in that the shape of the cavity is the same as the test piece, the volume of the cavity is equal to the volume of the test piece, and the inner surface of the cavity is polished smooth for accommodating the test piece.

6. A rock-concrete structure stability monitoring and early warning method based on static magnetic field detection as claimed in claim 5, wherein the cavity is located in a dense area of the bottom of the rock-concrete structure to be monitored, which is 20-50 cm away from the ground.

7. A rock-concrete structure stability monitoring and early warning method based on static magnetic field detection as claimed in claim 6, characterized in that when the test piece is placed in the cavity, one surface of the test piece 5mm x 5mm is placed outwards.

8. The static magnetic field detection-based rock-concrete structure stability monitoring and early warning method as claimed in claim 1, wherein the magnetic field sensor is a static magnetic field sensor and is insensitive to an alternating magnetic field.

9. The static magnetic field detection-based rock-concrete structure stability monitoring and early warning method as claimed in claim 1, wherein the magnetic field sensor is placed 2cm in front of the cavity and faces the cavity.

10. A rock-concrete structure stability monitoring and early warning method based on static magnetic field detection as claimed in any one of claims 1 to 9, characterized in that the value of the set threshold is 20%.

Background

In recent years, the problem of instability of rock or concrete structures such as buildings, bridges, mines and tunnels under the action of stress often occurs, and the safety of geotechnical engineering is seriously threatened. The method monitors the structural stability of the rock concrete, finds instability risks in time and carries out early warning, and is an important way for preventing and treating geotechnical engineering disasters.

At present, the monitoring technology for the stability of the rock-concrete structure body is mainly realized by measuring the displacement change of the structure by using an inclinometer or reflecting the displacement change outside the structure by using the deformation or settlement of a support or a building envelope, and the monitoring technology cannot reflect the change inside the rock-concrete structure body, so that the problems of insufficient reliability of the monitoring result and the like exist.

Disclosure of Invention

The invention provides a rock-concrete structure stability monitoring and early warning method based on static magnetic field detection, which aims to solve the technical problems that the existing rock-concrete structure stability monitoring and early warning method cannot reflect the change in a rock-concrete structure and the reliability of a monitoring result is insufficient.

In order to solve the technical problems, the invention provides the following technical scheme:

a rock-concrete structural body stability monitoring and early warning method based on static magnetic field detection comprises the following steps:

preparing a magnetic concrete test piece by using concrete and a magnetic material;

excavating a cavity which is matched with the test piece and used for accommodating the test piece on the rock-concrete structure body to be monitored;

fixing a magnetic field sensor at a preset distance right in front of the cavity, and testing the magnetic field intensity H of the current environment₀；

Placing the test piece into the cavity;

testing the magnetic field intensity of the test piece in the cavity by using the magnetic field sensor until the data of the magnetic field sensor is stable, and reading the initial magnetic field intensity H of the test piece in the cavity₁；

Periodically testing the magnetic field intensity H of the test piece in the compression deformation process according to a preset period_t；

Based on the change rate of the magnetic field intensity of the test piece, judging the stability of the rock-concrete structure body to be monitored according to a preset judgment criterion, and realizing the monitoring and early warning of the stability of the rock-concrete structure body to be monitored; wherein the preset criterion is as follows: the rate of change of magnetic field strength of the test piece, mu ═ H_t－H₁)/(H₁－H₀) The larger the size, the more unstable the rock-concrete structure, and when μ is equal to or greater than a set threshold value, the rock-concrete structure is at risk of instability.

Further, the preparation of the magnetic concrete test piece by using concrete and a magnetic material comprises the following steps:

mixing the concrete and the magnetic material according to the mass ratio of 5:1, and uniformly stirring by using a vibrating rod;

placing the mixed material of the concrete and the magnetic material into a mould, adding water, pouring, forming and curing;

and taking out the cured concrete block from the mold, cutting a sample from the middle part of the concrete block by using a cutting machine, and polishing the sample into a cuboid test piece with a smooth outer surface by using a polishing machine.

Further, the concrete is the concrete with the reference number C80; the magnetic material is iron-nickel alloy particles with the diameter of 1 mm; the volume of the mould is 20cm³The above; in willAnd placing the mixed material of the concrete and the magnetic material into a mould, adding water, pouring and forming, and curing for more than 28 days.

Further, the size of the rectangular parallelepiped test piece is 10mm × 5mm × 5 mm.

Further, the shape of the cavity is the same as that of the test piece, the volume of the cavity is equal to that of the test piece, and the inner surface of the cavity is polished smooth to accommodate the test piece.

Further, the cavity is located in a compact area, 20-50 cm away from the ground, of the bottom of the rock-concrete structure to be monitored.

Further, when the test piece is placed in the cavity, one side of the test piece 5mm × 5mm is placed outward.

Furthermore, the magnetic field sensor is a static magnetic field sensor and is insensitive to an alternating magnetic field.

Further, the magnetic field sensor is placed 2cm in front of the cavity and faces the cavity.

Further, the value of the set threshold is 20%.

The rock concrete structure stability monitoring and early warning method provided by the invention takes the positive correlation between the magnetic field strength and the stress and deformation in the process of compressing the magnetic material as the physical basis, places the magnetic concrete test piece in the rock concrete structure, and judges the bearing and deformation conditions of the rock concrete structure by testing the magnetic field strength of the magnetic concrete. When the bearing condition of the rock-concrete structure body changes, the stress and deformation of the magnetic concrete test piece can be caused to change, the change rate of the magnetic field strength of the magnetic concrete test piece in the compression deformation process is calculated through the magnetic field strength in the test environment, the initial magnetic field strength of the magnetic concrete test piece and the magnetic field strength after compression deformation, the bearing and deformation conditions of the rock-concrete structure body can be judged, and therefore the monitoring and early warning on the stability of the rock-concrete structure body are achieved.

The beneficial effects brought by the technical scheme provided by the invention at least comprise:

1. the detection method can reflect the change in the rock concrete structure body, and the evaluation result is more reliable.

2. After the magnetic concrete test piece is embedded into the rock concrete structure body, the stability of the rock concrete structure body can be monitored in real time at any time according to needs, and the instantaneity is good.

3. The method is suitable for monitoring and early warning of the stability of the overground and underground geotechnical engineering such as buildings, bridges, mines and tunnels, and has strong adaptability.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a method for monitoring and warning the stability of a rock-concrete structure based on static magnetic field detection according to a first embodiment of the present invention;

fig. 2 is a schematic flow chart of a rock-concrete structure stability monitoring and early warning method based on static magnetic field detection according to a second embodiment of the present invention;

fig. 3 is a schematic position diagram of a rock-concrete structure and a magnetic field sensor according to a second embodiment of the present invention.

Description of reference numerals:

1. a rock-concrete structure; 2. a magnetic concrete sample; 3. a cavity; 4. a magnetic field sensor;

5. a triangular fixed support; 6. a data line; 7. a host.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First embodiment

By monitoring the internal stress and deformation of the rock-concrete structure, the bearing condition and deformation condition of geotechnical engineering can be monitored, so that the stability of the rock-concrete structure can be accurately evaluated. Based on the above, the embodiment provides a rock-concrete structure stability monitoring and early warning method based on static magnetic field detection, which has good instantaneity, strong adaptability and high reliability, so as to solve the technical problems that the existing rock-concrete structure stability monitoring and early warning method cannot reflect the change in the rock-concrete structure and the reliability of the monitoring result is insufficient, and the method is suitable for monitoring the bearing condition and deformation condition of geotechnical engineering and evaluating the stability. The execution flow of the method is shown in fig. 1, and comprises the following steps:

s101, preparing a magnetic concrete test piece by using concrete and a magnetic material;

s102, excavating a cavity matched with the test piece and used for accommodating the test piece on the rock concrete structure body to be monitored;

s103, fixing a magnetic field sensor at a preset distance right in front of the cavity, and testing the magnetic field intensity H of the current environment₀；

S104, placing the test piece into the cavity;

s105, testing the magnetic field intensity of the test piece in the cavity by using the magnetic field sensor until the data of the magnetic field sensor is stable, and reading the initial magnetic field intensity H of the test piece in the cavity₁；

S106, periodically testing the magnetic field intensity H of the test piece in the compression deformation process according to a preset period_t；

S107, judging the stability of the rock-concrete structure body to be monitored according to a preset judgment criterion based on the change rate of the magnetic field intensity of the test piece, and realizing monitoring and early warning of the stability of the rock-concrete structure body to be monitored; the preset judgment criterion is as follows: the rate of change of magnetic field strength of the test piece, mu ═ H_t－H₁)/(H₁－H₀) The larger the size, the more unstable the rock-concrete structure, and when μ is equal to or greater than a set threshold value, the rock-concrete structure is at risk of instability.

It should be noted that, in this embodiment, the value of the set threshold is 20%; the magnetic field sensor is a static magnetic field sensor, is insensitive to an alternating magnetic field, and is placed 2cm right in front of the cavity. And the magnetic field intensity H in the test environment₀Reading initial magnetic field intensity H of magnetic concrete test piece in cavity₁Periodically testing the magnetic field intensity of the magnetic concrete test piece in the compression deformation processH_tIn the process, no power supply and no vibration interference are ensured around the device. Furthermore, the position and orientation of the magnetic field sensors should remain consistent during the test.

In conclusion, the monitoring and early warning method for the stability of the rock-concrete structure body of the embodiment judges the bearing and deformation conditions of the rock-concrete structure body by testing the magnetic field intensity of the magnetic concrete, and can realize monitoring and early warning for the stability of the rock-concrete structure body. The problems that the change of the interior of a rock concrete structure body cannot be reflected and the reliability of a monitoring result is insufficient in the prior art are solved. The method of the embodiment has strong applicability, and can be used for monitoring and early warning the stability of overground and underground geotechnical engineering such as buildings, bridges, mines and tunnels. In addition, after the magnetic concrete test piece is embedded into the rock-concrete structure, the stability of the rock-concrete structure can be monitored in real time at any time according to needs, and the instantaneity is good.

Second embodiment

Referring to fig. 2 and 3, the embodiment provides a rock-concrete structure stability monitoring and early warning method based on static magnetic field detection, and is suitable for monitoring the bearing condition and deformation condition of geotechnical engineering and evaluating the stability.

The execution flow of the method is shown in fig. 2, and comprises the following steps:

s201, determining the rock-concrete structural body 1 needing stability monitoring according to the monitoring requirement of geotechnical engineering, and selecting the position where the bottom of the rock-concrete structural body 1 is compact as a test site.

S202, taking the concrete material with the preparation label C80, adding iron-nickel alloy particles with the mass of 1/5 and the diameter of 1mm into the concrete material, and uniformly stirring the mixture by using a vibrating rod; placing the mixture of concrete and magnetic material into a container with a diameter of 20cm³Adding water into the large-scale mould, pouring and forming, and maintaining for more than 28 days; after the curing was completed, the concrete block was taken out of the mold, a small sample was cut out from the middle of the block by a cutter, and the cut sample was polished to a rectangular parallelepiped magnetic concrete sample 2 of 10mm × 5mm × 5mm by a small polishing machine.

S203, excavating a cavity 3 with the internal dimension of 10mm multiplied by 5mm at the position 20 cm-50 cm away from the ground at the bottom of the rock-concrete structure 1, and polishing the inner surface of the smooth cavity, wherein the 5mm multiplied by 5mm surface of the cavity 3 faces outwards and is used as an opening for filling the magnetic concrete sample 2.

S204, placing the magnetic field sensor 4 at a position 2cm in front of the cavity 3, wherein the detection end of the magnetic field sensor 4 is opposite to the cavity 3, fixing the magnetic field sensor 4 by using the triangular fixing support 5, and recording the position of the magnetic field sensor 4; the magnetic field sensor 4 is connected with a host 7 through a data line 6; starting magnetic field testing software on the host 7, and testing the environmental magnetic field intensity H by using the magnetic field sensor 4₀And transmits the data back to the host 7.

S205, the magnetic field sensor 4 is taken down from the triangular fixed support 5, the magnetic concrete sample 2 is placed in the cavity 3, the 5mm multiplied by 5mm surface of the magnetic concrete sample 2 faces outwards, and then the magnetic field sensor 4 is placed on the triangular fixed support 5 and fixed at the same position as that in S204.

S206, starting magnetic field testing software on the host 7, testing the magnetic field intensity of the magnetic concrete sample 2 in the cavity 3 by using the magnetic field sensor 4 until the data of the magnetic field sensor 4 is stable, and reading the initial magnetic field intensity H of the magnetic concrete sample 2 in the cavity 3₁。

S207, periodically testing the magnetic field intensity H of the magnetic concrete sample 2 in the compression deformation process_t；

S208, according to the environmental magnetic field intensity H₀Initial magnetic field intensity H of magnetic concrete sample 2₁And the magnetic field intensity H of the compression deformation process of the magnetic concrete sample 2_tThe magnetic field strength change rate μ ═ H of the magnetic concrete sample 2 was calculated_t－H₁)/(H₁－H₀)。

S209, the rate of change μ ═ H according to the magnetic field strength of magnetic concrete sample 2_t－H₁)/(H₁－H₀) The bearing condition and the deformation condition of the geotechnical engineering are monitored, the stability of the rock-concrete structural body 1 is evaluated, and the judgment criterion is as follows: the larger the change rate mu of the magnetic field strength of the magnetic concrete sample 2 is, the more unstable the rock-concrete structural body 1 is, and when mu is greater than or equal to 20%, the rock-concrete structural body 1 is at risk of instability.

Here, the magnetic field sensor 4 is staticA magnetic field sensor insensitive to an alternating magnetic field; magnetic field strength H in test environment₀Reading initial magnetic field intensity H of magnetic concrete sample 2 in cavity 3₁And periodically testing the magnetic field intensity H of the magnetic concrete sample 2 in the compression deformation process_tThe position and orientation of the magnetic field sensor 4 should be kept consistent, and no power supply and no vibration interference around the magnetic field sensor are ensured.

In summary, according to the method for monitoring and warning the stability of the rock-concrete structure in this embodiment, the magnetic concrete test piece is placed in the rock-concrete structure, the magnetic field strength in the environment, the initial magnetic field strength of the magnetic concrete test piece, and the magnetic field strength after compressive deformation are tested, the bearing and deformation conditions of the rock-concrete structure are judged according to the magnetic field strength change rate of the magnetic concrete test piece during the compressive deformation, and the stability of the rock-concrete structure is monitored and warned. The method has the advantages of strong applicability and capability of monitoring the stability of the rock concrete structure body in real time at any time according to requirements.

Further, it should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.

Finally, it should be noted that while the above describes a preferred embodiment of the invention, it will be appreciated by those skilled in the art that, once the basic inventive concepts have been learned, numerous changes and modifications may be made without departing from the principles of the invention, which shall be deemed to be within the scope of the invention. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.