Roof rock stratum fissure zone monitoring method

Abstract

The invention discloses a roof strata fissure zone monitoring method, which comprises the following steps: S1, layering an overlying strata in the vertical direction according to the height of the overlying strata to form a plurality of sublayers; s2, performing drilling operation on each sub-layer to form a mounting hole for mounting an optical fiber sensor, mounting the optical fiber sensor in each mounting hole, and monitoring the fracture development condition of each sub-layer in real time by using the optical fiber sensor so as to judge the development height of the fractured zone; s3, after the installation of the optical fiber sensor is completed, the installation hole is sealed by using concrete grout so as to prevent the interference of the external environment on the optical fiber sensor; and S4, the optical fiber sensor is connected with a monitoring station, so that the monitoring station can receive, process and analyze transmission data from the optical fiber sensor to judge the development height of the overlying strata fissure zone. The roof rock stratum fissure zone monitoring method has the advantages of simple steps, high monitoring efficiency and the like.

Description

Technical Field

[0001] The invention relates to the technical field of mining, and in particular to an optical fiber monitoring method for a roof rock stratum fracture zone. Background Art

[0002] The development height of the fracture zone in the working face roof is a key consideration in the working face mine pressure management, goaf fire prevention and extinguishing management, aquifer and surface water control. It is affected by the geological structure, mining and physical and mechanical properties of the rock mass in the roof rock layer. The harder the rock mass and the thicker the mined coal seam, the higher the development height of the fracture zone, the more complex the fracture field, the larger the spatial volume that can accumulate gas, the more water conduction channels there are, and the higher the degree of danger.

[0003] In the related technologies, the monitoring accuracy of roof fracture zones is low, it is easily affected by environmental interference, and it is impossible to conduct deep rock formation monitoring. Summary of the invention

[0004] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0005] (1) The initial investment in microseismic monitoring systems is large, including high-quality sensors, data acquisition equipment, software licenses, etc., and the subsequent operation and maintenance costs are relatively high. Due to factors such as environmental noise and instrument failure, false alarms may occur or actual microseismic events may not be detected. Its spatial resolution is limited and is not enough to clearly depict the specific damage path.

[0006] (2) The borehole peep method has a limited monitoring range. It mainly observes the internal situation through drilling, and its observation range is limited to the area around the borehole wall. For the entire monitoring body, the borehole represents only a local range in the form of a point or line. In the monitoring of a large-scale mine goaf, the borehole peep can only obtain the cracks, crushing and other conditions at the borehole location, and cannot directly reflect the actual status of the vast area between the boreholes. Image interpretation is subjective. The images obtained from the borehole peep instrument need to be manually interpreted and analyzed. Different operators may interpret the same image differently due to differences in experience, professional knowledge background and other factors. This subjectivity will affect the accuracy and reliability of the monitoring results to a certain extent. Moreover, for images of complex fracture networks or fracture zones, it is also difficult to accurately determine information such as the connectivity and development direction of the fractures. The borehole peep method has certain limitations in depth. As the depth of the borehole increases, the signal transmission of the peep device may be affected and the image quality will decrease. When the borehole depth exceeds the effective transmission distance of the peep instrument, it may not be possible to obtain a clear image or no image at all.

[0007] (3) Water injection tests are usually conducted in boreholes or specific test wells. They are essentially local tests, and their results can only reflect the fracture conditions within a limited range around the test point, and cannot represent the fracture conditions of the entire area. The pressure-flow data obtained from water injection tests often have multiple possible explanations. The same pressure drop and flow change may be caused by different fracture distributions, fracture connectivity, and other factors.

[0008] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0009] To this end, an embodiment of the present invention proposes an optical fiber monitoring method for roof rock fracture zones that has high monitoring accuracy, is not easily disturbed by the environment, and can monitor deep rock formations.

[0010] According to an embodiment of the present invention, a method for monitoring fracture zones in roof rock strata comprises: S1: according to the height of the overlying rock strata, the overlying rock strata is layered in the up and down directions to form a plurality of sub-layers; S2: drilling operations are performed on each of the sub-layers to form mounting holes for installing optical fiber sensors, and the optical fiber sensors are installed in each of the mounting holes, so as to utilize the optical fiber sensors to monitor the fracture development conditions of each of the sub-layers in real time to determine the development height of the fracture zone; S3: after the optical fiber sensors are installed, the mounting holes are sealed with concrete slurry to prevent the external environment from interfering with the optical fiber sensors; S4: the optical fiber sensors are connected to a monitoring station so that the monitoring station can receive, process and analyze the transmission data from the optical fiber sensors to determine the development height of the fracture zone in the overlying rock strata.

[0011] The method for monitoring the fracture zone of the roof rock strata of an embodiment of the present invention is configured with steps S1 to S4 to realize real-time monitoring of the overlying rock strata, accurately determine the height of the fracture zone, ensure the reliability and stability of data acquisition, reduce the occurrence rate of false alarms, and the monitoring and processing results are accurate and reliable, which can comprehensively reflect the fracture status of the overlying rock strata.

[0012] In some embodiments, in step S2, a PVC tube is used as a carrier of the optical fiber sensor, and the optical fiber sensor is transported into the installation hole through the PVC tube.

[0013] In some embodiments, there are multiple PVC tubes, and the multiple PVC tubes are arranged in sequence along the axial direction thereof, and the optical fiber sensor is installed on the outer peripheral side of the multiple PVC tubes.

[0014] In some embodiments, the optical fiber sensor is bonded to the outer peripheral surface of the PVC tube by epoxy resin glue, and the optical fiber sensor is fastened to the outer peripheral side of the PVC tube by a nylon tie.

[0015] In some embodiments, the optical fiber sensor includes a first optical fiber sensor and a second optical fiber sensor, the first optical fiber sensor and the second optical fiber sensor are both arranged on the outer peripheral side of the PVC tube, the first optical fiber sensor is arranged above the second optical fiber sensor, the first optical fiber sensor is used to detect the compressive strain of the sublayer, and the second optical fiber sensor is used to detect the tensile strain of the same sublayer.

[0016] In some embodiments, in step S2, the mounting hole includes a first section and a second section which are connected, the first section extends upward from the roof of the tunnel and is inclined toward the goaf, the second section extends along the length direction of the goaf and at least part of the second section is located above the goaf, at least one second section is provided in each sublayer, and the optical fiber sensor is disposed in the second section.

[0017] In some embodiments, there are a plurality of mounting holes, and the plurality of mounting holes are arranged in a plurality of rows along the up-down direction, and each row includes a plurality of mounting holes arranged at intervals along the width direction of the goaf.

[0018] In some embodiments, in step S3, the parameters of the concrete slurry are determined according to the rock properties of the sub-layers at different levels, the concrete slurry is proportioned according to the determined parameters, and the proportioned concrete slurry is injected into the installation holes of the corresponding sub-layers to seal the installation holes.

[0019] In some embodiments, in step S4, the monitoring station and the optical fiber sensor are connected by an optical cable, and a condensing agent is sprayed on the outer circumference of the optical cable to cool the optical cable.

[0020] In some embodiments, in step S4, the monitoring station draws an internal strain curve of the mounting hole according to the monitoring result of the optical fiber sensor, so that when the strain value exceeds 600 microstrain, cracks are generated in the sublayer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of a method for monitoring fracture zones in roof rock strata according to an embodiment of the present invention.

[0022] Figure 2 It is a trend profile of the monitoring system of the roof rock stratum fracture zone monitoring method according to an embodiment of the present invention.

[0023] Figure 3 It is a top view of the monitoring system of the roof rock stratum fracture zone monitoring method according to an embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of the installation of the optical fiber sensor and the PVC pipe of the roof rock fracture zone monitoring method according to an embodiment of the present invention.

[0025] Figure 5 It is a right view of the optical fiber sensor and the PVC pipe of the roof rock fracture zone monitoring method according to an embodiment of the present invention.

[0026] Monitoring method of fracture zone in roof rock strata 100;

[0027] Overlying rock layer 1; sublayer 11; mounting hole 12; first section 13; second section 14; goaf 15; coal pillar 16; optical fiber sensor 2; first optical fiber sensor 21; second optical fiber sensor 22; PVC pipe 3; tunnel 4; support body 5; mining working face 6; nylon tie 7. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] The following describes a roof rock fracture zone monitoring method 100 according to an embodiment of the present invention with reference to the accompanying drawings.

[0030] like Figure 1-Figure 5 As shown, the roof rock fracture zone monitoring method 100 according to an embodiment of the present invention includes steps S1 to S4.

[0031] S1: According to the height of the overburden stratum 1, the overburden stratum 1 is layered in the vertical direction to form a plurality of sub-layers 11. Specifically, Figure 1 and Figure 2 As shown, the overburden layer 1 on the roof is divided into a plurality of sub-layers 11 according to its height and distribution characteristics in the vertical direction (up and down direction).

[0032] S2: Drilling operations are performed on each sublayer 11 to form mounting holes 12 for mounting optical fiber sensors 2, and optical fiber sensors 2 are mounted in each mounting hole 12, so as to use the optical fiber sensors 2 to monitor the crack development of each sublayer 11 in real time, so as to determine the development height of the crack zone. Specifically, Figure 1-Figure 3 As shown, for each sublayer 11, a directional drill is used to perform precise drilling operations on the overlying rock stratum 1 of the tunnel 4 to form a mounting hole 12 for installing the optical fiber sensor 2. The position, depth and inclination angle of the mounting hole 12 need to be designed according to the specific conditions of the sublayer 11 to ensure that the optical fiber sensor 2 can accurately and stably monitor the development of the cracks. The optical fiber sensor 2 is then installed in each mounting hole 12, and the optical fiber sensing technology is used to monitor the development of the cracks in each sublayer 11 in real time to determine the development height and change trend of the crack zone.

[0033] S3: After the optical fiber sensor 2 is installed, the installation hole 12 is sealed with concrete slurry to prevent the external environment from interfering with the optical fiber sensor 2. Specifically, after the optical fiber sensor 2 is installed, in order to prevent the external environment (such as moisture, dust, temperature, etc.) from interfering with the optical fiber sensor 2 and affecting the accuracy and stability of the monitoring data, the installation hole 12 is sealed with concrete slurry, thereby ensuring the monitoring efficiency of the optical fiber sensor 2.

[0034] S4: The optical fiber sensor 2 is connected to the monitoring station so that the monitoring station can receive, process and analyze the transmission data from the optical fiber sensor 2 to accurately determine the development height of the fracture zone of the overburden stratum 1. Specifically, the optical fiber sensor 2 is connected to the monitoring station to establish a data transmission channel. The monitoring station can receive the transmission data from the optical fiber sensor 2 in real time, and process and analyze it to determine the development height and change trend of the fracture zone of the overburden stratum 1, providing a scientific basis for the management and maintenance of the overburden stratum 1. At the same time, the monitoring station can also store and back up the monitoring data for subsequent data analysis and research.

[0035] The method 100 for monitoring the fracture zone of the roof stratum of the embodiment of the present invention is provided with steps S1 to S4. The optical fiber sensor 2 can realize continuous monitoring of the overburden stratum 1. When the overburden stratum 1 collapses, the monitoring station can process the transmission data of the optical fiber sensor 2 to generate an optical fiber strain curve. The optical fiber strain curve can clearly reflect the changes inside the stratum, thereby accurately determining the height of the fracture zone. Compared with the microseismic monitoring system, the optical fiber sensor 2 of the method 100 for monitoring the fracture zone of the roof stratum of the embodiment of the present invention is not easily affected by electromagnetic interference, temperature changes and other environmental factors, which improves the reliability and stability of data acquisition and reduces the incidence of false alarms. Secondly, compared with the monitoring by the borehole peep method, the processing result of the method 100 for monitoring the fracture zone of the roof stratum of the embodiment of the present invention is accurate and reliable, and the image quality will not decrease with the increase of depth. Finally, the setting of the sensor in each sublayer 11, compared with the water injection test, the method 100 for monitoring the fracture zone of the roof stratum of the embodiment of the present invention performs a comprehensive monitoring of the overburden stratum 1, and can comprehensively reflect the fracture state of the overburden stratum 1.

[0036] In some embodiments, in step S2, the PVC tube 3 is used as a carrier of the optical fiber sensor 2, and the optical fiber sensor 2 is transported to the installation hole 12 through the PVC tube 3. Specifically, Figure 2-Figure 5 As shown, the optical fiber sensor 2 is installed on the outer peripheral side of the PVC pipe 3, and then the PVC pipe 3 with the optical fiber sensor 2 is sent into the installation hole 12 through a conveying tool, thereby providing a transportation basis for the optical fiber sensor 2, improving the installation efficiency of the optical fiber sensor 2, and reducing the transportation cost of the optical fiber sensor 2.

[0037] In some embodiments, there are multiple PVC tubes 3, and the multiple PVC tubes 3 are arranged in sequence along the axial direction thereof, and the optical fiber sensor 2 is installed on the outer peripheral side of the multiple PVC tubes 3. Specifically, Figure 4 and Figure 5 As shown, there are multiple PVC tubes 3, and the multiple PVC tubes 3 are arranged in sequence along the left and right directions, and the sum of the lengths of the multiple PVC tubes 3 is greater than the depth of the mounting hole 12, so that there is enough space for operation and adjustment during transportation. The optical fiber sensor 2 is installed and fixed on the outer peripheral side of the multiple PVC tubes 3, so that the optical fiber sensor 2 is transported through the multiple PVC tubes 3, and the arrangement of the multiple PVC tubes 3 can flexibly adjust the number and position of the PVC tubes 3 according to specific monitoring needs and the distribution of the overlying rock strata 1, so as to realize accurate monitoring of the overlying rock strata 1 in different areas and depths.

[0038] In some embodiments, the optical fiber sensor 2 is bonded to the outer peripheral surface of the PVC tube 3 by epoxy resin glue, and the optical fiber sensor 2 is fastened to the outer peripheral side of the PVC tube 3 by a nylon tie 7. Figure 4 and Figure 5 As shown, epoxy resin glue is used as an adhesive to bond the optical fiber sensor 2 to the outer peripheral surface of each PVC tube 3. The epoxy resin glue not only has excellent bonding strength and durability, but also can ensure a good seal between the optical fiber sensor 2 and the PVC tube 3 to prevent the external environment from interfering with or damaging the sensor. In addition, since the nylon cable tie 7 has the characteristics of high strength, wear resistance and easy operation, the optical fiber sensor 2 is additionally fixed by the nylon cable tie 7, which effectively prevents the sensor from loosening or falling off during use, and enhances the stability of the optical fiber sensor 2 on the PVC tube 3. Therefore, the dual fixing method of epoxy resin glue and nylon cable tie 7 not only ensures the firm installation of the optical fiber sensor 2 on the PVC tube 3, but also can effectively prevent the sensor from loosening or falling off during use, thereby improving the installation efficiency of the optical fiber sensor 2 on the PVC tube 3.

[0039] In some embodiments, the optical fiber sensor 2 includes a first optical fiber sensor 21 and a second optical fiber sensor 2. The first optical fiber sensor 21 and the second optical fiber sensor 2 are both arranged on the outer peripheral side of the PVC tube 3. The first optical fiber sensor 21 is arranged above the second optical fiber sensor 2. The first optical fiber sensor 21 is used to detect the compressive strain of the sublayer 11, and the second optical fiber sensor 2 is used to detect the tensile strain of the same sublayer 11. Specifically, Figure 2-Figure 5As shown, the first optical fiber sensor 21 is installed above the PVC pipe 3. Since compressive strain usually occurs when the rock layer is squeezed by the upper or surrounding rock mass, the compressive strain of the sublayer 11 can be detected by the first optical fiber sensor 21, and the stress change of the rock layer under pressure can be accurately monitored to provide key compression deformation data. The second optical fiber sensor 2 is installed below the PVC pipe 3. Since tensile strain usually occurs when the rock layer is subjected to tensile force, or tensile stress is generated by the tension generated by the movement of the surrounding rock mass, the tensile strain of the sublayer 11 can be detected by the second optical fiber sensor 2. Therefore, by setting the first optical fiber sensor 21 and the second optical fiber sensor 2, the compressive strain and tensile strain data of the same sublayer 11 can be obtained at the same time, and the deformation and force information of the rock layer can be accurately obtained, thereby improving the accuracy of the detection results.

[0040] In some embodiments, in step S2, the mounting hole 12 includes a first section 13 and a second section 14 which are connected, the first section 13 extends upward from the top plate of the tunnel 4 and is inclined toward the goaf 15, the second section 14 extends along the length direction of the goaf 15 and at least part of the second section 14 is located above the goaf 15, at least one second section 14 is provided in each sublayer 11, and the optical fiber sensor 2 is provided in the second section 14. Specifically, as Figure 2 As shown, the first section 13 extends upward from the roof of the mining tunnel 4 and is inclined toward the goaf 15, which reduces the resistance in the drilling process, improves the drilling efficiency of the first section 13, and reduces the drilling cost of the first section 13. The second section 14 extends in the left-right direction and is located above the goaf 15, so that the second section 14 can cover the height range of the entire fracture zone, and at least one second section 14 is provided in each sublayer 11, which ensures the continuity and comprehensiveness of monitoring and helps to detect the strain state of the rock formation at different depths and positions.

[0041] In some embodiments, there are multiple mounting holes 12, and the multiple mounting holes 12 are arranged in multiple rows along the up-down direction, and each row includes a plurality of mounting holes 12 spaced apart along the width direction of the goaf 15. Specifically, the second sections 14 of the multiple mounting holes 12 are arranged in multiple rows along the up-down direction, and at least one row of mounting holes 12 is provided in each sub-layer 11, thereby ensuring that the sub-layers 11 at different heights can be monitored by the optical fiber sensor 2, and each row includes a plurality of second sections 14 spaced apart along the front-back direction, thereby ensuring that the monitoring range of the optical fiber sensor 2 can cover the entire width of the goaf 15, thereby improving the accuracy and efficiency of monitoring.

[0042] In some embodiments, in step S3, the parameters of the concrete slurry are determined according to the rock properties of the sub-layers 11 at different levels, the concrete slurry is proportioned according to the determined parameters, and the proportioned concrete slurry is injected into the mounting hole 12 of the corresponding sub-layer 11 to seal the mounting hole 12. Specifically, the parameters of the concrete slurry are determined according to the rock properties of different levels on site, and the parameters may be elastic modulus, Poisson's ratio, tensile strength, etc., and then the concrete slurry of different proportions is segmented and grouted according to different levels on site, and the proportioned concrete slurry is injected into the opening of the mounting hole 12 of the corresponding sub-layer 11. After the slurry is completely solidified, the opening of the mounting hole 12 is sealed to prevent external substances such as water and mud from entering the mounting hole 12, avoid damage to the internal optical fiber sensor 2, reduce the influence of external factors on the monitoring results, ensure that the optical fiber sensor 2 and other monitoring equipment can accurately capture the stress changes inside the rock formation, and ensure the accuracy of the monitoring results of the optical fiber sensor 2.

[0043] In some embodiments, in step S4, the monitoring station and the optical fiber sensor 2 are connected by an optical cable, and a condensing agent is sprayed on the outer peripheral side of the optical cable to cool the optical cable. Specifically, the optical fiber sensor 2 at the opening of the installation hole 12 is thermally welded to the dedicated long-distance communication optical cable and protected by a junction box, and is led to the ground and connected to the monitoring station. The condensing agent is sprayed at the opening of the installation hole 12 with a local range of about 100 cm in length to cool the optical cable. The condensing agent can quickly absorb the heat on the surface of the optical cable, thereby reducing the temperature of the optical cable, reducing the loss of the optical signal in the optical cable, and improving the transmission efficiency of the optical cable.

[0044] In some embodiments, in step S4, the monitoring station draws the internal strain curve of the installation hole 12 according to the monitoring results of the optical fiber sensor 2, so that when the strain value exceeds 600 microstrain, the sublayer 11 generates cracks. Specifically, the monitoring station can draw the internal strain curve of the borehole according to the monitoring results. When the rock formation collapses and cracks are generated in the rock formation, the strain generated by the optical fiber sensor 2 in the crack zone is greater than 600 microstrain. Therefore, the value corresponding to 600 microstrain of the optical fiber strain curve can be used as a basis for judging the height of the roof crack zone.

[0045] The working process of the roof rock fracture zone monitoring method 100 of the embodiment of the present invention is as follows:

[0046] (1) Analyze the borehole columnar diagram of the target area and calculate the layered distribution thickness, lithology, joint and fissure development degree, and physical and mechanical parameters of the coal rock of the overlying rock layer 1.

[0047] (2) According to the distribution characteristics of the overlying rock layer 1 and the construction conditions of the tunnel 4, the damage of the collapse zone to the optical fiber sensor 2 is avoided, the influence of the collapse zone on the optical fiber monitoring results of the fracture zone is reduced, and the starting inclination angle of the fracture zone optical fiber monitoring borehole is determined.

[0048] (3) Using an empirical formula, calculate the height of the crack zone to ensure that the height of the optical fiber sensor 2 can exceed the complete crack zone.

[0049] (4) In order to fully monitor the fracture zone, the fiber optic drilling slope section is perpendicular to the working surface, and the horizontal section is parallel to the working surface. The horizontal sections are arranged at different strata to measure the fracture development conditions at different rock strata.

[0050] (5) Bury the optical fiber and use PVC as a carrier to push the optical fiber into the hole.

[0051] (6) Apply epoxy resin glue to both sides of the single section of PVC tube 3, place the optical fiber on the glue outside the PVC tube 3, and apply glue again. After the glue is cured, use nylon tie 7 to tie it to the outside of the PVC tube 3 at a certain distance.

[0052] (7) The first optical fiber sensor 21 is located on the upper surface of the PVC pipe 3 to monitor the compressive strain, and the second optical fiber sensor 2 is located on the lower surface of the PVC pipe 3 to monitor the tensile strain, and the tensile and compressive strains of the rock can be monitored simultaneously.

[0053] (8) Determine the parameters of the concrete slurry, elastic modulus, Poisson's ratio, tensile strength, etc. according to the rock properties of different layers at the site, and inject concrete slurries of different proportions in sections according to the positions of the sub-layers 11 of different layers at the site. After the slurry solidifies, seal the hole.

[0054] (9) The optical fiber sensor 2 at the hole mouth is hot-melted to the dedicated long-distance communication optical cable and protected with a junction box, and then led to the ground to establish a monitoring station.

[0055] (10) At the borehole mouth, a condensing agent is sprayed on a local area of ​​the optical cable with a length of about 100 cm to cool it down, and the monitoring distance of the optical fiber from the borehole mouth to the bottom of the hole can be determined.

[0056] (11) Draw the internal strain curve of the borehole based on the monitoring results.

[0057] (12) Determination of the height of the fracture zone. When the overlying rock layer 1 collapses and fractures occur in the rock layer, the optical fiber strain in the fracture zone is generally greater than 600 microstrain. Therefore, the value corresponding to 600 microstrain of the optical fiber strain curve is used as the basis for determining the height of the fracture zone in the roof.

[0058] In summary, the roof rock fracture zone monitoring method 100 of the embodiment of the present invention has the following advantages:

[0059] (1) The designed roof rock fracture zone optical fiber sensor 2 can realize continuous monitoring of fracture zone rock strain and fracture zone development height.

[0060] (2) By precisely placing the optical fiber sensor 2 in the mounting hole 12 and fixing it with the PVC tube 3 and the nylon tie 7, the stability and accuracy of the optical fiber sensor 2 in different rock formations are ensured; when the overlying rock formation 1 collapses, the optical fiber strain curve can clearly reflect the changes inside the rock formation, thereby accurately determining the height of the fracture zone with a resolution of millimeters. Compared with related technologies, the optical fiber sensor 2 is not easily affected by electromagnetic interference, temperature changes and other environmental factors, which greatly improves the reliability and stability of data acquisition and reduces the incidence of false alarms.

[0061] (3) The present invention provides a method for identifying the fracture zone of the roof rock layer, which realizes a process flow with simple sensor installation and wide monitoring range. The use of a directional drilling rig for drilling, combined with the segmented grouting technology, not only speeds up the construction progress, but also ensures the installation quality of the optical fiber sensor 2. During the whole process, no complicated equipment and technical support are required, which reduces the construction difficulty.

[0062] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0063] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0064] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0066] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0067] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for monitoring fracture zones in roof rock formations, characterized in that: include: S1: According to the height of the overlying rock layer, the overlying rock layer is layered in the up and down directions to form a plurality of sub-layers; S2: drilling each of the sub-layers to form a mounting hole for mounting an optical fiber sensor, and mounting the optical fiber sensor in each of the mounting holes, so as to use the optical fiber sensor to monitor the development of cracks in each of the sub-layers in real time to determine the development height of the crack zone; S3: After the optical fiber sensor is installed, the installation hole is sealed with concrete slurry to prevent the external environment from interfering with the optical fiber sensor; S4: The optical fiber sensor is connected to a monitoring station so that the monitoring station can receive, process and analyze the transmission data from the optical fiber sensor to determine the development height of the fracture zone of the overlying rock strata.

2. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: In step S2, a PVC tube is used as a carrier of the optical fiber sensor, and the optical fiber sensor is transported into the installation hole through the PVC tube.

3. The method for monitoring the fracture zone of the roof rock layer according to claim 2, characterized in that: There are multiple PVC tubes, which are arranged in sequence along their axial direction, and the optical fiber sensor is installed on the outer peripheral side of the multiple PVC tubes.

4. The method for monitoring the fracture zone of the roof rock layer according to claim 3, characterized in that: The optical fiber sensor is bonded to the outer peripheral surface of the PVC tube by epoxy resin glue, and the optical fiber sensor is fastened to the outer peripheral side of the PVC tube by a nylon tie.

5. The method for monitoring the fracture zone of the roof rock layer according to claim 3, characterized in that: The optical fiber sensor includes a first optical fiber sensor and a second optical fiber sensor, wherein the first optical fiber sensor and the second optical fiber sensor are both arranged on the outer peripheral side of the PVC tube, the first optical fiber sensor is arranged above the second optical fiber sensor, the first optical fiber sensor is used to detect the compressive strain of the sublayer, and the second optical fiber sensor is used to detect the tensile strain of the same sublayer.

6. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: In step S2, the mounting hole includes a first section and a second section which are connected, the first section extends upward from the roof of the tunnel and is inclined toward the goaf, the second section extends along the length direction of the goaf and at least part of the second section is located above the goaf, at least one second section is provided in each sublayer, and the optical fiber sensor is disposed in the second section.

7. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: There are a plurality of mounting holes, which are arranged in a plurality of rows along the up-down direction, and each row includes a plurality of mounting holes which are arranged at intervals along the width direction of the goaf.

8. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: In step S3, the parameters of the concrete slurry are determined according to the rock properties of the sub-layers at different levels, the concrete slurry is proportioned according to the determined parameters, and the proportioned concrete slurry is injected into the installation holes of the corresponding sub-layers to seal the installation holes.

9. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: In step S4, the monitoring station and the optical fiber sensor are connected by an optical cable, and a condensing agent is sprayed on the outer circumference of the optical cable to cool the optical cable.

10. The method for monitoring the fracture zone of the roof rock layer according to claim 1, characterized in that: In step S4, the monitoring station draws an internal strain curve of the mounting hole according to the monitoring result of the optical fiber sensor, so that when the strain value exceeds 600 microstrain, cracks are generated in the sublayer.

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