Rock stratum slippage monitoring device and method

Abstract

The invention provides a rock stratum slippage monitoring device and method, and the device comprises a sleeve which is used for penetrating through a fracture surface of a rock stratum, the sleeve is made of a brass material, and the plane where the perpendicular bisector of the axis of the sleeve is located forms a reference plane; the optical fiber extends along the direction of the sleeve, and the optical fiber is fixedly arranged on the inner wall of the sleeve; and the sensors comprise a plurality of grating strain sensors, the plurality of grating strain sensors are arranged in the sleeve and are connected in series on the optical fiber at intervals along the extension direction of the optical fiber, and the grating strain sensors are arranged on the optical fibers on the two sides of the reference surface. By applying the technical scheme provided by the invention, the problem of inaccurate monitoring of the rock stratum slippage condition in the prior art can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of rock formation exploration, and in particular to a rock formation slippage monitoring device. Background Art

[0002] Fault activation refers to the phenomenon that faults in rock mass slide under the influence of mining. It is mainly manifested as the fault changes from a bonded state to a cracked state, and the medium around the fault makes adaptive adjustment movements, accompanied by huge energy release, causing casualties and property losses. Fault activation is actually an instability phenomenon caused by the shear stress on the fracture surface reaching and exceeding its shear strength. The impact of mining activities leads to dynamic changes in the friction coefficient of the fault. When the dynamic friction coefficient of the coal rock mass in the fault zone exceeds the static friction coefficient of the fault, the fault will become activated and unstable, leading to deformation and damage of the tunnel surrounding rock, water inrush, and induced impact mine pressure and other disasters.

[0003] In the prior art, a variety of strain, stress and hydraulic sensors are usually installed in each rock layer at the fracture surface to detect the stress and other parameter changes of each rock layer, and the stress changes of the rock layer are calculated to predict the slip of the rock layer. However, this monitoring method requires the construction of multiple boreholes, which is large in engineering volume and time, and the monitoring accuracy is easily affected by the quality of instrument installation, resulting in inaccurate early warning. Summary of the invention

[0004] The present invention provides a rock stratum slippage monitoring device and method, so as to solve the problem of inaccurate monitoring of rock stratum slippage in the prior art.

[0005] According to one aspect of the present invention, a rock formation slip monitoring device is provided, which includes: a casing, the casing is used to pass through the fracture surface of the rock formation, the casing is made of brass material, and the plane where the perpendicular bisector of the axis of the casing is located forms a reference surface; an optical fiber, the optical fiber extends along the direction of the casing, and the optical fiber is fixedly arranged on the inner wall of the casing; a sensor, the sensor includes a grating strain sensor, a plurality of grating strain sensors are arranged, the plurality of grating strain sensors are all arranged in the casing, and are connected in series on the optical fiber at intervals along the extension direction of the optical fiber, and the optical fibers located on both sides of the reference surface are provided with grating strain sensors.

[0006] Furthermore, the sensor also includes a grating temperature sensor, and the grating temperature sensor and a plurality of grating strain sensors are connected in series on the optical fiber.

[0007] Furthermore, the grating temperature sensor is arranged in the middle of the sleeve, and the plurality of grating strain sensors are symmetrically arranged on both sides of the grating temperature sensor.

[0008] Furthermore, at least four grating strain sensors are provided, and at least two grating strain sensors are provided on both sides of the grating temperature sensor.

[0009] Furthermore, the sleeve has a blocking end and an open end that are arranged opposite to each other, and the open end is provided with an extension component, which is detachably connected to the sleeve and is used to drive the sleeve to pass through the fracture surface.

[0010] Furthermore, the extension assembly includes a plurality of extension tubes, and the plurality of extension tubes are detachably connected in sequence.

[0011] According to another aspect of the present invention, a rock formation sliding monitoring method is provided, and the rock formation sliding monitoring method comprises:

[0012] Step 1: Drilling a hole on the inner wall of the tunnel toward the fracture surface of the rock formation to form an installation hole, wherein the installation hole passes through the fracture surface;

[0013] Step 2: inserting the rock formation slip monitoring device into the installation hole, the rock formation slip monitoring device being the above-mentioned rock formation slip monitoring device;

[0014] Step 3: Obtain the feedback signal from the sensor, and determine the risk level of rock slippage at the fracture surface based on the feedback signal.

[0015] Furthermore, in step 2, after the rock formation slip monitoring device is inserted into the installation hole, the reference surface of the casing coincides with the fracture surface.

[0016] Furthermore, the rock formation sliding monitoring device is the rock formation sliding monitoring device of claim 3, and the feedback signal is the total strain ε of a single grating strain sensor per unit time. Where λ is the reflection wavelength of the grating strain sensor, Δλ is the change in reflection wavelength, and P e is the core elastic-optic coefficient of the optical fiber, ξ is the core thermo-optic coefficient of the optical fiber, α is the core thermal expansion coefficient of the optical fiber, and ΔT is the temperature change obtained by the grating temperature sensor per unit time.

[0017] Furthermore, when the absolute value of the maximum total strain of the multiple grating strain sensors is greater than 0 and less than 20,000, the production activities are carried out normally; when the absolute value of the maximum total strain of the multiple grating strain sensors is greater than or equal to 20,000, the production activities are stopped.

[0018] By applying the technical solution of the present invention, a mounting hole passing through the fracture surface can be opened in the rock layer, and the casing of the slip monitoring device can be installed into the mounting hole so that the reference surface on the casing coincides with the fracture surface. When the rock layers on both sides of the fracture surface slip relatively, the rock layer will drive the casing made of brass material to bend, and the grating strain sensor close to the inner wall of the casing will deform together with the casing. The grating strain sensor located on the inner side of the bend is compressed and shortened, and the grating pitch therein becomes smaller; the grating strain sensor located on the outer side of the bend is stretched and lengthened, and the grating pitch therein becomes larger. At this time, the fiber grating demodulator measures the reflection wavelength of each sensor, and analyzes the slip of the rock layer through the wavelength data analysis system. Compared with the monitoring device in the traditional technical solution, the detection device provided by the present application can complete the detection of fault slip by analyzing the deformation of the grating strain sensor in the casing, without setting a variety of different sensors at multiple locations of the rock layer, reducing the construction time and construction accuracy requirements, thereby ensuring the accuracy of the monitoring of the rock layer slip monitoring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 The structure diagram of the rock formation sliding monitoring device provided by the present invention is shown;

[0021] Figure 2 A schematic diagram showing the casing provided by the present invention when the casing is deformed due to rock stratum sliding;

[0022] Figure 3 A structural schematic diagram showing the rock stratum slip monitoring device provided by the present invention being inserted into a mounting hole.

[0023] The above drawings include the following reference numerals:

[0024] 01, reference surface; 02, tunnel; 03, fracture surface;

[0025] 100, casing; 200, optical fiber; 300, grating temperature sensor; 400, grating strain sensor; 500, extension tube; 600, fiber Bragg grating demodulator. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, an embodiment of the present invention provides a rock formation sliding monitoring device, which includes a casing 100, an optical fiber 200 and a sensor. The casing 100 is used to pass through the fracture surface 03 of the rock formation, and the casing 100 is made of brass material. The plane where the perpendicular bisector of the axis of the casing 100 is located forms a reference plane 01. The optical fiber 200 extends along the direction of the casing 100, and the optical fiber 200 is fixedly arranged on the inner wall of the casing 100. The sensor includes a grating strain sensor 400, and a plurality of grating strain sensors 400 are arranged. The plurality of grating strain sensors 400 are all arranged in the casing 100, and are connected in series on the optical fiber 200 at intervals along the extension direction of the optical fiber 200. The optical fiber 200 located on both sides of the reference plane 01 is provided with a grating strain sensor 400. The rock formation sliding monitoring device also includes a fiber grating demodulator 600, which is used to monitor the reflection wavelength of the grating strain sensor 400.

[0028] By applying the technical solution of the present invention, a mounting hole passing through the fracture surface 03 can be opened in the rock formation, and the casing 100 of the slip monitoring device can be installed into the mounting hole so that the reference surface 01 on the casing 100 coincides with the fracture surface 03. Figure 2 As shown, when the rock layers on both sides of the fault surface 03 slip relatively, the rock layers will cause the brass casing 100 to bend, and the grating strain sensor 400 close to the inner wall of the casing 100 will deform together with the casing 100. The grating strain sensor 400 located on the inner side of the bend will be compressed and shortened, and the grating pitch therein will be reduced; the grating strain sensor 400 located on the outer side of the bend will be stretched and lengthened, and the grating pitch therein will be increased. At this time, the fiber grating demodulator 600 measures the reflection wavelength of each sensor, and analyzes the slip of the rock layer through the wavelength data analysis system. Compared with the monitoring device in the traditional technical solution, the detection device provided by the present application can complete the detection of fault slip by analyzing the deformation of the grating strain sensor 400 in the casing 100, without setting a variety of different sensors at multiple locations of the rock layer, reducing the construction time and construction accuracy requirements, and thus ensuring the accuracy of the rock layer slip monitoring device.

[0029] Specifically, the sensor also includes a grating temperature sensor 300, and the grating temperature sensor 300 and a plurality of grating strain sensors 400 are connected in series on the optical fiber 200. The grating pitch of the grating strain sensor 400 is related to both temperature and force. In the present application, by setting the grating temperature sensor 300 and correcting the reflection wavelength of the grating strain sensor 400 by the signal of the grating temperature sensor 300, the accuracy of the rock formation slip monitoring device can be improved. At the same time, the grating temperature sensor 300 and the grating strain sensor 400 are simultaneously set in the casing 100, and there is no need to drill holes in the rock formation again, which also ensures the construction efficiency.

[0030] Furthermore, the grating temperature sensor 300 is arranged in the middle of the sleeve 100, and the plurality of grating strain sensors 400 are symmetrically arranged on both sides of the grating temperature sensor 300. Through the above arrangement, the grating temperature sensor 300 is arranged in an area with a smaller deformation degree, thereby ensuring that the grating temperature sensor 300 is subjected to a smaller stress as much as possible, and ensuring the accuracy of the measurement of the grating temperature sensor 300.

[0031] In a specific embodiment of the present application, at least four grating strain sensors 400 are provided, and at least two grating strain sensors 400 are provided on both sides of the grating temperature sensor 300. Through the above configuration, at least two grating strain sensors 400 can be provided on both sides of the fracture surface 03, and monitoring can be performed through multiple sensors to reduce the noise of the measurement data and ensure the accuracy of the rock mass monitoring parameters on each side of the fracture surface 03.

[0032] Specifically, the sleeve 100 has a blocking end and an open end that are arranged opposite to each other, and an extension component is arranged at the open end, and the extension component is detachably connected to the sleeve 100, and the extension component is used to drive the sleeve 100 to pass through the fracture surface 03. Through the above arrangement, the sleeve 100 can be extended by the extension component, so that the sleeve 100 moves along the installation hole to reach a specified position.

[0033] like Figure 3 As shown, the extension assembly includes a plurality of extension tubes 500, and the plurality of extension tubes 500 can be detachably connected in sequence. After being connected in sequence, the extension tubes 500 can play the role of extending the casing 100. The detachable connection of the plurality of extension tubes 500 can facilitate the carrying of the extension assembly underground, and the extension tube 500 can not only protect the optical fiber, but also serve as a ruler, so that the construction personnel can accurately grasp the depth of the measuring tube entering the measuring installation hole, thereby ensuring that the casing 100 is accurately delivered to the fault surface.

[0034] Optionally, the extension tube 500 may be a PVC tube.

[0035] Optionally, both the sleeve 100 and the extension tube 500 may be provided with a threaded structure to facilitate installation and removal of the sleeve 100 and the extension assembly.

[0036] The present application also provides a rock formation sliding monitoring method, referring to Figure 3 As shown, the rock slip monitoring method includes:

[0037] Step 1: Use tomography software to determine the fracture surface 03 where the rock slip detection device needs to be installed, and drill a hole on the inner wall of the tunnel 02 toward the fracture surface 03 of the rock formation to form an installation hole. The installation hole passes through the fracture surface 03 and is perpendicular to the fracture surface 03.

[0038] Step 2: Insert the rock formation slip monitoring device into the installation hole through a plurality of extension tubes 500, wherein the rock formation slip monitoring device is the rock formation slip monitoring device mentioned above.

[0039] Step 3: Obtain the feedback signal of the sensor, and determine the risk level of rock slippage at the fracture surface 03 based on the feedback signal.

[0040] By analyzing and setting the detection device provided by the present application in the rock formation, the detection of fault slip can be completed, and there is no need to set a variety of different sensors at multiple locations in the rock formation, which reduces the construction time and construction accuracy requirements, thereby ensuring the accuracy of the rock formation slip monitoring device for monitoring. Because the grating is very sensitive to changes in the characteristic parameters of the optical signal, high-resolution measurement can be achieved, further improving the monitoring effect. In addition, in the field of rock formation monitoring, optical fiber is used as the transmission medium, and the monitoring device is not affected by electromagnetic interference. Compared with electrical sensors, it has better anti-interference performance and is suitable for complex environmental conditions. At the same time, the sensor used in the present invention does not require an external power supply, and its working principle is based on optical principles. Therefore, it can be used in an environment without power or difficult to access, and has high reliability and safety.

[0041] Specifically in step 2, after the rock formation slip monitoring device is inserted into the installation hole, the reference surface 01 of the casing 100 coincides with the fracture surface 03. The above arrangement can ensure that the distances from both ends of the casing 100 to the fracture surface 03 are the same, and minimize the difference in deformation between the two ends of the casing 100.

[0042] Specifically, when the grating temperature sensor 300 and the grating strain sensor 400 are simultaneously arranged in the sleeve 100, the broadband incident light enters the optical fiber 200 from one end of the grating strain sensor 400. After encountering the grating strain sensor 400, most of the wavelengths of light directly pass through the grating strain sensor 400 as transmitted light, and a small amount of light with a special wavelength of λ is reflected back.

[0043] The relationship between the reflection wavelength λ and the grating pitch λ can be expressed as:

[0044] λ=2n eff Λ;

[0045] Where: neff is the refractive index of the fiber core, Λ is the grating pitch;

[0046] The grating pitch Λ is related to two factors: temperature and force, while the fiber core refractive index n eff is also a variable, so the following formula is derived. The relationship between the temperature change ΔT, the strain change Δε and the reflection wavelength λ can be expressed as:

[0047] Δλ=[(1-P e )Δε+(ξ+α)ΔT]λ;

[0048] Where: λ is the reflection wavelength of the grating strain sensor, Δλ is the change in reflection wavelength, P e is the core elastic-optic coefficient of the optical fiber, ξ is the core thermo-optic coefficient of the optical fiber, α is the core thermal expansion coefficient of the optical fiber, and ΔT is the temperature change obtained by the grating temperature sensor per unit time.

[0049] The fiber Bragg grating in the fiber Bragg grating temperature sensor is only affected by temperature, so the temperature change ΔT can be expressed as:

[0050]

[0051] Where: 温度 is the reflection wavelength of the fiber Bragg grating temperature sensor, Δλ 温度 is the change in reflection wavelength of the fiber Bragg grating temperature sensor.

[0052] Therefore, the strain change Δε can be calculated as: The Δε at each moment i Sum the total response variable:

[0053] Reference Figure 3 As shown, taking the case where four grating strain sensors 400 are provided, the total strains of the two grating strain sensors 400 located at the lower side of the fault surface 03 are ε1 and ε2 respectively, and the total strains of the two grating strain sensors 400 located at the upper side of the fault surface 03 are ε3 and ε4 respectively. The current fault activation risk level can be judged according to the values ​​of ε1, ε2, ε3 and ε4 according to the following Tables 1 and 2, and corresponding measures can be taken.

[0054] Table 1 Reverse fault activation risk level classification

[0055]

[0056]

[0057] Table 2 Normal fault activation risk level classification

[0058]

[0059]

[0060] When the fault is in a no-risk, low-risk, or medium-risk state, it can be judged that the rock formation is relatively stable and production activities can be carried out normally. When the fault is in a high-risk state, it is considered that the fault is about to become activated and unstable. Production should be stopped immediately, personnel should be evacuated, and corresponding countermeasures should be taken to prevent loss of life and property.

[0061] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0062] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0063] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0064] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0065] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rock stratum slip monitoring device, characterized in that: The rock formation sliding monitoring device comprises: A casing (100), the casing (100) being used to pass through a fracture surface (03) of a rock formation, the casing (100) being made of a brass material, and the plane where the perpendicular midline of the axis of the casing (100) lies forms a reference plane (01); An optical fiber (200), the optical fiber (200) extending in the direction of the sleeve (100), and the optical fiber (200) being fixedly arranged on the inner wall of the sleeve (100); A sensor, the sensor comprising a grating strain sensor (400), wherein a plurality of the grating strain sensors (400) are provided, the plurality of the grating strain sensors (400) are all provided in the sleeve (100), and are connected in series on the optical fiber (200) at intervals along the extension direction of the optical fiber (200), and the grating strain sensors (400) are all provided on the optical fiber (200) located on both sides of the reference plane (01).

2. The rock formation sliding monitoring device according to claim 1, characterized in that: The sensor further comprises a grating temperature sensor (300), wherein the grating temperature sensor (300) and a plurality of the grating strain sensors (400) are connected in series on the optical fiber (200).

3. The rock formation sliding monitoring device according to claim 2, characterized in that: The grating temperature sensor (300) is arranged in the middle of the sleeve (100), and a plurality of grating strain sensors (400) are symmetrically arranged on both sides of the grating temperature sensor (300).

4. The rock formation sliding monitoring device according to claim 3 is characterized in that: At least four grating strain sensors (400) are provided, and at least two grating strain sensors (400) are provided on both sides of the grating temperature sensor (300).

5. The rock formation sliding monitoring device according to claim 1, characterized in that: The sleeve (100) has a blocking end and an open end that are arranged opposite to each other, and the open end is provided with an extension component, the extension component is detachably connected to the sleeve (100), and the extension component is used to drive the sleeve (100) to pass through the fracture surface (03).

6. The rock formation sliding monitoring device according to claim 5, characterized in that: The extension assembly comprises a plurality of extension tubes (500), and the plurality of extension tubes (500) are detachably connected in sequence.

7. A rock stratum slip monitoring method, characterized in that: The rock formation sliding monitoring method comprises: Step 1: drilling a hole on the inner wall of the tunnel (02) toward the fracture surface (03) of the rock formation to form a mounting hole, wherein the mounting hole passes through the fracture surface (03); Step 2: inserting a rock formation slippage monitoring device into the installation hole, wherein the rock formation slippage monitoring device is the rock formation slippage monitoring device according to any one of claims 1 to 6; Step three: obtaining a feedback signal from the sensor, and determining the risk level of slippage of the rock formation at the fracture surface (03) based on the feedback signal.

8. The rock formation sliding monitoring method according to claim 7, characterized in that: In the second step, after the rock formation slip monitoring device is inserted into the installation hole, the reference surface (01) of the casing (100) coincides with the fracture surface (03).

9. The rock formation sliding monitoring method according to claim 8, characterized in that: The rock formation sliding monitoring device is the rock formation sliding monitoring device according to claim 3, the feedback signal is the total strain ε of a single grating strain sensor (400) per unit time, Wherein, λ is the reflection wavelength of the grating strain sensor (400), Δλ is the change in reflection wavelength, and P e is the core elastic-optic coefficient of the optical fiber (200), ξ is the core thermo-optic coefficient of the optical fiber (200), α is the core thermal expansion coefficient of the optical fiber (200), and ΔT is the temperature change acquired by the grating temperature sensor (300) per unit time.

10. The rock formation sliding monitoring method according to claim 9, characterized in that: When the absolute value of the maximum total strain of the plurality of grating strain sensors (400) is greater than 0 and less than 20,000, the production activities are carried out normally; when the absolute value of the maximum total strain of the plurality of grating strain sensors (400) is greater than or equal to 20,000, the production activities are stopped.

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