A method for measuring the roof control range of the unit support in the ultra-advanced mining roadway

Abstract

The present invention describes a method for measuring the roof control range of a unit support in the ultra-advanced extraction roadway. The steps are as follows: S1, fiber Bragg grating displacement gauges are arranged along the roof strike and roof dip at the roadway roof to cover the contact surface between the unit support and the roadway roof, and the fiber Bragg grating displacement gauges transmit monitoring data to a computer; S2, a measurement fiber section is set on the fiber Bragg grating displacement gauges, and the measurement fiber section includes the maximum subsidence point of the settlement deformation of the roadway roof; S3, the overall deformation height of the measurement fiber section is calculated respectively under the conditions of having and not having the unit support for roof control; S4, the relative deformation amount of fiber settlement with and without the unit support is calculated; S5, a plane coordinate diagram after arranging the fiber Bragg grating displacement gauges on the roadway roof is drawn in the computer, and the coordinates of the relative deformation amount of fiber settlement of the fiber Bragg grating displacement gauges are marked in the plane coordinate diagram. The covered area formed by connecting the coordinates of the relative deformation amount of fiber settlement in sequence is the roof control range of the unit support.

Description

Technical Field

[0001] The present invention relates to the technical field of roadway support, and particularly to a method for measuring the roof control range of unit supports in the ultra-advanced mining roadway. Background Art

[0002] With the increase in the depth of coal seam mining, the initial surrounding rock stress faced by the mining roadway also increases significantly. Especially in the advanced areas of the two roadways of the working face, which are directly affected by the mining of the working face, the stress can usually reach more than twice the original rock stress. The support requirements are high and the difficulty is great, and the support equipment fails frequently.

[0003] As the top priority of improving the quality and efficiency of coal safety mining, the stability control of the mining roadway is usually achieved by using unit support to control the roof in the advanced area of the working face as a passive support reinforcement method. This method can keep the anchoring system working smoothly under the influence of high-intensity mining and maintain the integrity and stability of the roof of the ultra-advanced mining roadway.

[0004] Due to the unclear synergistic relationship between the unit support and the active support mainly composed of bolt and cable supports, the model and layout standard of the unit support have been in an empirical operation state for a long time. There are often phenomena such as the unit support seriously affecting the function of the bolt and cable supports, and in severe cases, large-scale support failure and roof caving accidents will occur, affecting normal production. Therefore, it is of great significance to clarify the relationship of the passive support effect of the advanced unit support for reducing the occurrence of disaster accidents in the mining roadway. One of the important tasks is to obtain the stress change of the roof of the ultra-advanced mining roadway and determine the roof control range of the unit support to help complete the scientific selection of the unit support and the determination of the support plan.

[0005] Currently, the stress and strain conditions are generally obtained by monitoring the roof stress, setting up measuring stations on the roadway surface, or monitoring support equipment such as bolts and cables. These methods usually have the following problems: The surface monitoring device and the use of the support medium are both indirect ways to obtain data, and the obtained results cannot fully reflect the actual state of the roadway and are seriously affected by the properties of the medium; The bolts, cables, meshes and steel strips on the roof of the ultra-advanced mining roadway are densely arranged, and the roof is severely damaged and deformed. The existing technical methods are too idealized, and their reaction effects in the actual application of the on-site mine are poor. Summary of the Invention

[0006] To solve the problems existing in the above-mentioned prior art, the present invention provides a method for measuring the roof control range of unit supports in the ultra-advanced mining roadway, and its specific technical solution is as follows:

[0007] A method for measuring the roof control range of unit supports in the ultra-advanced mining roadway includes the following steps:

[0008] S1. Along the strike and dip of the roadway roof, fiber Bragg grating displacement sensors are arranged on the contact surface between the covering unit support and the roadway roof. The fiber Bragg grating displacement sensors are electrically connected to a computer and transmit monitoring data to the computer.

[0009] S2. A measurement fiber section is set on the fiber Bragg grating displacement sensor, and the measurement fiber section includes the maximum subsidence point of the settlement deformation of the roadway roof.

[0010] S3. Calculate the overall deformation height of the measurement fiber section under the conditions of having and not having unit support roof control respectively. The steps are as follows:

[0011] S301. When there is unit support roof control, the measurement fiber section is evenly divided into N fiber intervals at equal distances, and each fiber interval is evenly divided into n fiber units. The calculation formula for the overall deformation height of the measurement fiber section is as follows:

[0012]

[0013] In the formula,

[0014] h is the overall deformation height of the measurement fiber section under unit support roof control; L AB is the initial length of the fiber interval under unit support roof control; ε i is the uniform fiber strain of the fiber unit under unit support roof control; n is the number of fiber units under unit support roof control; d is the length of the fiber unit under unit support roof control; N is the number of fiber intervals under unit support roof control;

[0015] S302. When there is no unit support roof control, the measurement fiber section is evenly divided into N' fiber intervals at equal distances, and each fiber interval is evenly divided into n' fiber units. The calculation formula for the overall deformation height of the measurement fiber section is as follows:

[0016]

[0017] In the formula,

[0018] h' is the overall deformation height of the measurement fiber section under no unit support roof control; L OP is the initial length of the fiber interval under no unit support roof control; ε' i is the uniform fiber strain of the fiber unit under no unit support roof control; n' is the number of fiber units under no unit support roof control; d' is the length of the fiber unit under no unit support roof control; N' is the number of fiber intervals under no unit support roof control;

[0019] S4. Calculate the relative deformation of fiber settlement with and without unit support. The formula is:

[0020] Δh = h′ - h

[0021] In the formula,

[0022] Δh is the relative deformation of optical fiber settlement with or without the unit support; h' is the overall deformation height of the optical fiber without roof control by the unit support; h is the overall deformation height of the optical fiber with roof control by the unit support.

[0023] S5. Draw a plane coordinate diagram of the roadway roof after installing the fiber Bragg grating displacement sensor in the computer, and mark the coordinates of the relative deformation of optical fiber settlement of the fiber Bragg grating displacement sensor in the plane coordinate diagram. The covered area formed by connecting the coordinates of the relative deformation of optical fiber settlement in sequence is the roof control range of the unit support.

[0024] Furthermore, the measurement method further includes: Step S6, obtaining the stress change of the roadway roof within the roof control range of the unit support; the stress of the roadway roof = the optical fiber strain * the elastic modulus of the medium, where the elastic modulus of the medium is obtained by measuring through a uniaxial compression deformation experiment, and the optical fiber strain is obtained by calculating the settlement height of any section of the optical fiber. The calculation formula for the settlement height of any section of the optical fiber is:

[0025]

[0026]

[0027] In the formula,

[0028] h x-1,x is the settlement height of any optical fiber section with roof control by the unit support; h' x-1,x is the settlement height of any optical fiber section without roof control by the unit support; x is any fixed point where the optical fiber branches out; L AB is the initial length of the optical fiber section with roof control by the unit support; L OP is the initial length of the optical fiber section without roof control by the unit support; ε AB is the uniform optical fiber strain of the optical fiber section with roof control by the unit support; ε OP is the uniform optical fiber strain of the optical fiber section without roof control by the unit support.

[0029] Furthermore, the method for setting the measured optical fiber section on the fiber Bragg grating displacement sensor is: Set two fixed points on the optical fiber arranged along the axial direction or the dip direction of the roadway. The optical fiber section between the two fixed points is the measured optical fiber section, and the measured optical fiber section includes the maximum subsidence point formed by the settlement of the roadway roof under load.

[0030] Furthermore, a plurality of fiber Bragg grating displacement sensors are set, and their layout method is: On the rectangular dip side of the contact surface, with its edge as the standard interval, several equi - length fiber Bragg grating displacement sensors are respectively arranged on both sides; on the rectangular strike side of the contact surface, with its edge as the standard interval, several equi - length fiber Bragg grating displacement sensors are respectively arranged on both sides.

[0031] Furthermore, the fiber Bragg grating displacement gauge is arranged in the roadway roof by drilling. The width of the drill hole is set to 2 cm - 3 cm, and the depth of the drill hole is set to 20 cm - 50 cm.

[0032] Furthermore, after the fiber Bragg grating displacement gauge is arranged, a medium material is used to seal the drill hole; taking the elastic modulus as the comparison standard, the difference ratio between the medium material after solidification and the roadway roof rock stratum is less than 5%.

[0033] Furthermore, a drilling device is used for drilling operations; the drilling device includes a horizontal directional drill, and a grouting chamber fixedly arranged at the tail end of the drill bit of the horizontal directional drill; the horizontal directional drill is provided with a hollow drill pipe, and the hollow drill pipe penetrates through the grouting chamber; a stirring mechanism is arranged on the outer surface of the hollow drill pipe, and the stirring mechanism is composed of a plurality of fan blades arranged at intervals on the outer surface of the hollow drill pipe; the stirring mechanism is arranged inside the grouting chamber; the hollow drill pipe is provided with slurry outlet holes, and the slurry outlet holes are arranged near the tail end of the drill bit of the horizontal directional drill; a fiber optic cable is fixedly connected to the tail end of the grouting chamber.

[0034] Furthermore, a centralizer is arranged inside the horizontal directional drill, and the centralizer is used to provide support and guidance for the drilling operation of the rock-breaking cone bit; the horizontal directional drill is also provided with an expanding rock cone bit, and the expanding rock cone bit is arranged at the tail end of the rock-breaking cone bit and rotates synchronously with the rock-breaking cone bit for expanding the diameter of the drilled hole; a laser alignment instrument is also arranged inside the horizontal directional drill for realizing real-time direction and position monitoring during the drilling process.

[0035] Furthermore, a limiting plate is also arranged inside the grouting chamber, and the limiting plate is arranged near the slurry outlet holes of the hollow drill pipe for controlling the concrete flow rate inside the embedding unit bin.

[0036] Furthermore, the horizontal directional drill is provided with a rock-breaking cone bit, and the rock-breaking cone bit is set to be conical and conical teeth are arranged on its outer surface.

[0037] Based on the above technical solutions, the present invention has the following beneficial effects:

[0038] 1. The method described in the present invention arranges the fiber Bragg grating displacement gauge in the unit support roof contact area by drilling in a way that can fully and effectively cover the roof contact area, and can directly measure the actual stress inside the roadway roof, without being affected by the state of the roadway roof rock stratum and the support density, and will not interfere with normal production operations and support operations.

[0039] 2. The method described in the present invention combines theoretical calculation and measured results effectively through fiber Bragg grating displacement gauges and based on geometric principles, mutually verifies, and reasonably determines the roof control range of the unit support, achieving the technical purpose of qualitatively and quantitatively determining the roof control range of the unit support, solving the current situation that the design of the unit support support plan is mainly based on experience, and filling the technical gap in this aspect.

[0040] 3. The method described in the present invention can monitor the actual strain and actual stress of the roadway roof, achieve the purpose of dynamically and linearly monitoring the stress change of the roadway roof, make the monitoring data more accurate and reasonable, and can be used under similar working conditions such as inside mines and tunnel rock soils, having the technical advantages of strong practicability and wide application. Brief Description of the Drawings

[0041] Figure 1 : Table of rock mechanical property parameters of different types of rock strata in the roadway roof;

[0042] Figure 2 : Schematic diagram of the contact surface between the unit support and the roadway roof and the roof control area;

[0043] Figure 3 : Table of drilling depth parameters for different rock types;

[0044] Figure 4 : Schematic diagram of the deformation of the roadway roof under overlying rock stress and the deformation state of the optical fiber (1);

[0045] Figure 5 : Schematic diagram of the deformation of the roadway roof under overlying rock stress and the deformation state of the optical fiber (2);

[0046] Figure 6 : Schematic diagram of the deformation of the roadway roof under overlying rock stress and the deformation state of the optical fiber (3);

[0047] Figure 7 : Schematic diagram of the deformation of the roadway roof with and without the support of the unit support;

[0048] Figure 8 : Schematic diagram of the process of burying fiber Bragg grating displacement gauges in the roadway roof rock stratum;

[0049] Figure 9 : Schematic diagram of the process flow of the method described in the present invention;

[0050] Figure 10 : Schematic diagram of the wrapping state of the fiber Bragg grating displacement gauge in the drilling medium material;

[0051] Figure 11 : Schematic diagram of the roadway cross-section during the process of precast concrete transportation for drilling and burying fiber Bragg grating displacement gauges;

[0052] Figure 12 : Schematic diagram of the cross-section of the transportation gateway in the 1101 working face;

[0053] Figure 13 : Schematic diagram of the division of the actually measured roof control area of the support in the experimental unit of the 1101 working face;

[0054] Figure 14 : Schematic diagram of the structure of the drilling device.

[0055] Symbol Explanation

[0056] 1 - Horizontal directional drill, 101 - Rock - breaking roller bit, 102 - Centralizer, 103 - Rock - enlarging roller bit, 104 - Laser alignment instrument; 2 - Grouting chamber, 201 - Restricting plate; 3 - Hollow drill pipe, 301 - Grout outlet hole; 4 - Fan blade. Specific Embodiment

[0057] It should be noted that in the present invention, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. Therefore, this specification and the claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of components as the criterion for distinction.

[0058] The following is combined with the attached Figure 1 - attached Figure 14 , and the present invention is described in detail in the form of embodiments.

[0059] The present invention describes a method for measuring the roof control range of the unit support in the ultra - front - section extraction roadway, including the following steps:

[0060] S1, Prepare the medium material for borehole sealing. After solidification, this medium material should have rock mechanical properties similar to those of the roof rock stratum of the roadway to be measured.

[0061] The rock mechanical properties include, but are not limited to, rock type, density g / cm 3 , elastic modulus GPa, compressive strength MPa, shear modulus GPa, and Poisson's ratio.

[0062] "Similar" means that taking the elastic modulus as the comparison standard, the difference ratio between the medium material and the roof rock stratum of the roadway to be measured is less than 5%, so as to ensure that the physical properties of the medium material are closer to the rock mechanical properties of the actual roadway roof rock stratum.

[0063] The rock mechanical properties are obtained by measuring the uniaxial compression deformation experiment of samples in a laboratory environment. Among them, the medium material samples are made of concrete, and multiple samples are made by changing the component ratio of the concrete, and the experimental data are respectively recorded for selection and distinction; the roof rock stratum samples of the roadway are made through on - site actual mining, and the data are as shown in the attached Figure 1 as follows.

[0064] S2, as shown in the appendix Figure 2 As shown, along the strike and dip of the roadway roof at the roadway roof, fiber Bragg grating displacement sensors are arranged to cover the contact surface between the unit support and the roadway roof. The fiber Bragg grating displacement sensors are electrically connected to a computer and transmit the collected monitoring data to the computer.

[0065] To effectively cover the roof control range of the unit support and ensure the comprehensiveness of the monitoring data, the arrangement method of the fiber Bragg grating displacement sensors is set as follows:

[0066] 1. On the rectangular dip side of the contact surface, taking its edge as the standard interval, several fiber Bragg grating displacement sensors of equal length are arranged on both sides respectively; on the rectangular strike side of the contact surface, taking its edge as the standard interval, several fiber Bragg grating displacement sensors of equal length are also arranged on both sides respectively;

[0067] 2. The fiber Bragg grating displacement sensors are arranged on the roadway roof by drilling. The drilling width is set to 2 cm - 3 cm, and the drilling depth is preferably set to 20 cm - 50 cm;

[0068] The drilling depth can also be adjusted according to the rock mass properties of the roadway roof. The rock mass properties include but are not limited to the compressive strength R C , the rock mass integrity degree, the rock mass integrity index k v , the rock mass volume joint number J V , as shown in the appendix Figure 3 showing specific parameter data;

[0069] 3. After the fiber Bragg grating displacement sensors are arranged, the drilling holes are sealed with the medium material determined in step S1. After the medium material is cured, the fiber Bragg grating displacement sensor operation is carried out.

[0070] S3, as shown in the appendix Figure 4 As shown, a large number of on-site measured data show that the closer to the two sides of the roadway, the smaller the settlement amount of the roadway roof, and the settlement amount is almost 0. Therefore, in this step, the roof settlement amounts at the left end and the right end of the roadway roof are set to 0.

[0071] Whether there is a unit support for roof control or not, the roadway roof will settle under the action of rock stratum stress and self-weight. The calculation principles and calculation processes of the two are the same. Therefore, in this step and subsequent steps, the situation with unit support for roof control is taken as the main example for calculation, and the situation without unit support for roof control will be correspondingly explained during the calculation process.

[0072] As shown in the appendix Figure 4 - appendix Figure 6As shown, in the case of roof control with unit supports, two fixed points are set on the optical fiber arranged along the axial direction or dip direction of the roadway. The optical fiber section between the two fixed points is the measured optical fiber section, and the measured optical fiber section should include the maximum subsidence area formed by the settlement of the roadway roof under load, such as the fixed points A to D shown in the attachment. Figure 4 The fixed points A to D shown in the attachment.

[0073] The measured optical fiber section is evenly divided into N optical fiber intervals at equal distances. For the convenience of subsequent calculation and explanation, the length of each optical fiber interval is defined as L AB ; Each optical fiber interval is further divided into n optical fiber units at equal distances, and the length of each optical fiber unit is defined as d; It should be ensured that the length of the optical fiber interval is greater than the length of 1 optical fiber unit, that is, L AB > d.

[0074] In this step, taking the attachment Figure 5 as an example, the measured optical fiber section AD is evenly divided into 3 optical fiber intervals, namely the optical fiber interval AB, the optical fiber interval BC, and the optical fiber interval CD. Since the fiber Bragg grating displacement sensor is arranged at the set position of the roadway roof by drilling and is sealed with the same medium material as the roadway roof, the fiber Bragg grating displacement sensor is well integrated with the roadway roof and undergoes synchronous deformation with the roadway roof; Moreover, the roadway roof is mainly composed of rock and the deformation amplitude is small, so the points B1, C1, D1 corresponding to the points B, C, D on the deformed optical fiber are approximately vertically corresponding.

[0075] In the case of no unit support for roof control, the schematic symbols are adjusted to O - R, for example, the fixed points O to R are set.

[0076] When the roadway roof undergoes settlement deformation, the optical fiber undergoes synchronous deformation under the stress of the roof. Since the fiber strain of adjacent optical fiber units is uniformly equal, and thus the fiber strain of the optical fiber interval is also uniform, therefore, the length of the stretched optical fiber interval can be calculated using the uniform strain obtained from the fiber subsidence change and the uniform strain between the optical fiber units.

[0077] S301. Define the length of the stretched optical fiber interval with unit support for roof control as Then there is

[0078]

[0079] In the formula,

[0080] is the length of the stretched optical fiber interval under unit support for roof control;

[0081] L AB is the initial length of the optical fiber interval under unit support for roof control;

[0082] ε ABFor the uniform strain of the optical fiber in the optical fiber section under the control of the unit support

[0083] ε i For the uniform strain of the optical fiber in the optical fiber unit under the control of the unit support

[0084] n is the number of optical fiber units under the control of the unit support

[0085] d is the length of the optical fiber unit under the control of the unit support

[0086] Define the length after stretching of the optical fiber section without the control of the unit support as Then there is

[0087]

[0088] In the formula,

[0089] Is the length after stretching of the optical fiber section without the control of the unit support

[0090] L OP Is the initial length of the optical fiber section without the control of the unit support

[0091] ε OP Is the uniform strain of the optical fiber in the optical fiber section without the control of the unit support

[0092] ε′ i Is the uniform strain of the optical fiber in the optical fiber unit without the control of the unit support

[0093] n′ is the number of optical fiber units without the control of the unit support

[0094] d′ is the length of the optical fiber unit without the control of the unit support

[0095] S302. In the case of the control of the unit support, when the optical fiber undergoes tensile deformation, the length deformation of each optical fiber unit is d·ε i , and the length of the stretched optical fiber unit is d(1 + ε i ). As shown in Attachment Figure 4 and 5 shown,

[0096] The vertical displacement formed by each optical fiber unit is defined as Δh i , then there is

[0097]

[0098] The overall deformation height of the optical fiber is defined as h, then there is

[0099]

[0100] In the formula,

[0101] Δh i is the vertical displacement formed by each optical fiber unit under the roof control with unit supports;

[0102] h is the overall deformation height of the optical fiber under the roof control with unit supports;

[0103] L AB is the initial length of the optical fiber section under the roof control with unit supports;

[0104] ε i is the uniform strain of the optical fiber of each optical fiber unit under the roof control with unit supports;

[0105] n is the number of optical fiber units under the roof control with unit supports;

[0106] d is the length of each optical fiber unit under the roof control with unit supports;

[0107] N is the number of optical fiber sections under the roof control with unit supports.

[0108] In the case of no roof control with unit supports, the vertical displacement formed by each optical fiber unit is defined as Δh′ i , then there is

[0109]

[0110] The overall deformation height of the optical fiber is defined as h′, then there is

[0111]

[0112] In the formula,

[0113] Δh′ i is the vertical displacement formed by each optical fiber unit in the case of no roof control with unit supports;

[0114] h′ is the overall deformation height of the optical fiber in the case of no roof control with unit supports;

[0115] L OP is the initial length of the optical fiber section in the case of no roof control with unit supports;

[0116] ε′ i is the uniform strain of the optical fiber of each optical fiber unit in the case of no roof control with unit supports;

[0117] n′ is the number of optical fiber units in the case of no roof control with unit supports;

[0118] d′ is the length of each optical fiber unit in the case of no roof control with unit supports;

[0119] N′ is the number of optical fiber sections in the case of no roof control with unit supports.

[0120] S303. Calculate the relative deformation of the optical fiber settlement with and without the unit support, and compare this relative deformation with the threshold value of the roof control range, then the roof control range of the unit support can be determined.

[0121] That is:

[0122] Δh = h′ - h

[0123] In the formula,

[0124] Δh is the relative deformation of the optical fiber settlement with and without the unit support;

[0125] h′ is the overall deformation height of the optical fiber under the condition of roof control without the unit support;

[0126] h is the overall deformation height of the optical fiber under the condition of roof control with the unit support.

[0127] The comparison table of the threshold value of the roof control range is as follows:

[0128] Roof control threshold ζ / mm 35 < ζ ≤ 50 20 < ζ ≤ 35 10 < ζ ≤ 20 ζ < 10 Roof control effect Very good Average Weak Very weak

[0129] It is obtained that when the relative deformation of the optical fiber settlement is less than 20 mm, the roof control ability of the unit support at this place is weak and cannot achieve a good roof control effect.

[0130] In the above steps S301 - S303, in order to avoid the result obtained by laying the optical fiber not being able to fully reflect the actual state of the roadway, it is preset that the fiber optic grating displacement gauge in the roadway roof is coupled with the rock formation at its burial place.

[0131] S4. To explore the action relationship between the passive support of the advanced unit support and the roadway roof and obtain the stress change of the roadway roof within the roof control range of the unit support, it is necessary to monitor the stress of the roadway roof within the roof control range. Since the roof stress = optical fiber strain * medium elastic modulus, and the measurement method of the cut-off elastic modulus is given in step S1, therefore, it is necessary to calculate the settlement height of any section of the optical fiber. The specific calculation process is as follows.

[0132] During the optical fiber monitoring process, since a section of optical fiber is divided into several optical fiber units, the optical fiber settlement is simulated as continuous settlement along the axis. And based on dividing a section of optical fiber evenly and equidistantly into N optical fiber intervals, and each optical fiber interval is further equidistantly divided into n optical fiber units, in the case of roof control with the unit support, combined with Appendix Figure 4 to Appendix Figure 6 It can be known that: L AB = L BC = L CD ≈ L x-1x , ε AB = ε BC = ε CD ≈ ε x-1x .

[0133] In ΔABB j In

[0134]

[0135] Therefore

[0136]

[0137] In ΔC1D1M

[0138]

[0139] Therefore

[0140]

[0141] In ΔACC1

[0142] Since According to It can be known that Therefore

[0143]

[0144] Since the strain difference between adjacent optical fibers is only the strain value of one optical fiber unit, the strains of adjacent optical fibers are approximately regarded as the same. Therefore

[0145]

[0146] That is It can be summarized and concluded that

[0147] The settlement height of any optical fiber segment with unit support roof control is

[0148]

[0149] Based on the above calculation steps, the settlement height of any optical fiber segment without unit support roof control is

[0150]

[0151] In the above formula

[0152] h x-1，x Is the settlement height of any optical fiber segment with unit support roof control;

[0153] h′ x-1，x Is the settlement height of any optical fiber segment without unit support roof control;

[0154] x is any fixed point where the optical fiber branches out;

[0155] L ABis the initial length of the optical fiber section under the control of the unit support;

[0156] L OP is the initial length of the optical fiber section without the control of the unit support;

[0157] ε AB is the uniform strain of the optical fiber in the optical fiber section under the control of the unit support;

[0158] ε OP is the uniform strain of the optical fiber in the optical fiber section without the control of the unit support.

[0159] S5. Draw a plane coordinate diagram of the roadway roof after installing the fiber Bragg grating displacement sensors in the computer, and mark the coordinates of the relative deformation of the fiber settlement of each fiber Bragg grating displacement sensor in the plane coordinate diagram. The covered area formed by sequentially connecting the coordinates of the relative deformation of the fiber settlement is the controlled roof range of the unit support.

[0160] In the above embodiment, to obtain excellent optical fiber layout effects, this embodiment also records a drilling device.

[0161] The drilling device includes a small horizontal directional drill 1 and a grouting chamber 2 fixedly arranged at the tail end of the drill bit of the horizontal directional drill.

[0162] The drill pipe of the horizontal directional drill is set as a hollow drill pipe 3, and the hollow drill pipe penetrates through the grouting chamber 2. A stirring mechanism is arranged on the outer surface of the hollow drill pipe 3. The stirring mechanism is composed of a plurality of fan blades 4 arranged at intervals on the outer surface of the hollow drill pipe, and the stirring mechanism is arranged inside the grouting chamber 2.

[0163] The hollow drill pipe 3 is provided with slurry outlet holes 301, and the slurry outlet holes 301 are arranged near the tail end of the drill bit of the horizontal directional drill 1.

[0164] A fiber optic cable is fixedly connected to the tail end of the grouting chamber 2.

[0165] During the operation of the horizontal directional drill, while the drill pipe drives the drill bit to rotate and drill, grouting operation is carried out. After the slurry flows out from the slurry outlet holes of the drill pipe, it is continuously stirred by the fan blades inside the grouting chamber and flows out from the tail end of the grouting chamber to complete the hole sealing operation. After the horizontal directional drill drills out of the hole, the fiber optic cable is removed to complete the laying operation of the fiber optic cable inside the hole.

[0166] As a preference:

[0167] 1. The rock-breaking roller 1O1 of the horizontal directional drill 1 is set as conical, and conical teeth are arranged on its outer surface. The conical teeth are arranged in a regular spiral pattern on the surface of the rock-breaking roller for breaking and cutting the rock in the formation to ensure the smooth progress of the drilling.

[0168] 2. Inside the horizontal directional drill 1, a centralizer 102 is installed. The centralizer 102 can be adjusted according to the formation conditions, providing support and guidance for the drilling operation of the rock-breaking cone 101, maintaining the stability of the rock-breaking cone 101, and preventing it from deviating from the predetermined trajectory.

[0169] 3. The horizontal directional drill 1 is also equipped with an underreaming cone 103. The underreaming cone 103 is arranged at the tail end of the rock-breaking cone 101 and rotates synchronously with the rock-breaking cone 101, which is used to enlarge the diameter of the drilled hole, facilitating the subsequent transportation of concrete and the laying of optical fibers.

[0170] 4. A laser alignment instrument 104 is installed inside the horizontal directional drill 1, which is used to monitor the real-time direction and position during the drilling process to ensure the accuracy of drilling. The laser alignment instrument 104 is provided with a laser transmitter and a receiver, which are used to provide accurate positioning information in the state of high-speed movement.

[0171] 5. A restricting plate 201 is also arranged inside the grouting chamber 2. The restricting plate 201 is arranged near the slurry outlet hole 301 of the hollow drill pipe 3, which is used to control the concrete flow rate inside the buried unit bin, ensure that the concrete is evenly filled in the hole, and its position inside the buried unit bin can be adjusted according to the actual operation requirements to change the concrete transportation rate.

[0172] The operating principle of the drilling device is described as follows:

[0173] The rock-breaking cone breaks the formation rock and drills a hole by rotating and applying pressure;

[0174] When the rock-breaking cone deviates from the predetermined trajectory, the laser alignment instrument automatically adjusts the traveling direction of the rock-breaking cone to ensure that the rock-breaking cone travels along the set route;

[0175] The horizontal directional drill is used for drilling at a specific depth and angle;

[0176] The centralizer is used to ensure the stability of the drill bit during the drilling process and avoid deviation caused by uneven formation;

[0177] The underreaming cone enlarges the diameter of the drilled hole, creating enough space for the transportation of concrete and optical fibers. During the transportation of concrete, the stirring fan blades continuously stir the concrete to prevent the concrete from prematurely solidifying due to standing during transportation. By maintaining the uniformity of the concrete, the stirring fan blades ensure the quality of the final pouring;

[0178] The method recorded in this embodiment is further described below through specific operation implementations.

[0179] Taking the belt conveyor gate road in the 1101 working face of a certain coal mine as an example, the relevant parameters of this working face are as follows:

[0180] The roof is supported by high-strength threaded steel bolts with a spacing of 800×800 mm. There are 8 bolts, which are fixed in series along the roadway section direction with steel belts. The cable bolts have a spacing of 1600×2400 mm. The top part uses a welded wire mesh made of Φ6.5 mm steel bars with a specification of 100×100 mm. In the middle of the roadway, a ZQ4000 / 22 / 48D(A) type unit support is used to support the roof. The support height is 2.2 m to 4.8 m, and the top beam size is 2200 mm×630 mm.

[0181] S1. Through the parameter investigation of the roadway roof in the working face, the following rock property parameters in the roof area are obtained:

[0182]

[0183] S2. Rock samples are obtained from the roadway roof. In the laboratory, experimental instruments such as a uniaxial compression testing machine, a press, a displacement sensor, a strain gauge, a digital oscilloscope, or a data collector are used for testing and data collection.

[0184] The specific experimental process is as follows:

[0185] S201. Place the rock sample in the compression fixture of the uniaxial compression testing machine to ensure its correct position.

[0186] S202. Apply an axial load at a constant strain rate, such as 0.1 mm / min, to start the compression experiment.

[0187] S203. Record the stress and strain of the rock sample in real time, where stress = applied force / sample cross-sectional area, and strain = displacement / initial height.

[0188] S204. After the experiment is completed, stop applying the load, remove the sample, and record the failure mode, such as brittle failure or plastic deformation.

[0189] A reference example of the experimental data is as follows in the table:

[0190] Applied stress (MPa) Displacement (mm) Strain (‰) 10 0.08 0.8 20 0.16 1.6 30 0.24 2.4 40 0.36 3.6 50 0.41 4.1

[0191] S3. Calculate the elastic modulus.

[0192] The calculated elastic modulus of the rock sample is 12.20 GPa. Compare it with the elastic modulus of the roof rock layer, which is 12.16 GPa.

[0193] Difference = (12.20 - 12.16)×100% = 4%

[0194] Through the uniaxial compression deformation experiment, the elastic modulus of the rock sample obtained in the experiment is similar to that of the roof rock layer, with a difference of 4%, verifying the similarity between the mechanical properties of the rock sample and the actual engineering application.

[0195] S4, reference Figures 10 - 13 After the above operations are completed, the fiber Bragg grating strain gauge is buried.

[0196] From the above steps, it can be seen that the rock layer on the roof of the rubber transport drift tunnel of the 1101 working face is relatively hard rock, so the drilling depth of the drilling device above the roof is 15cm.

[0197] S5, arranging fiber Bragg grating displacement meters of equal length on both sides of the support top rectangular inclination as a standard interval, and arranging fiber Bragg grating displacement meters of equal length on both sides of the support top rectangular strike edge as a standard interval.

[0198] S6, after the solidification of the dielectric material reaches the standard, the system will perform strain detection to obtain the stress change of the top plate. After the unit bracket works normally for one week, the data of each fiber Bragg grating displacement meter is collected at the preset position in contact with the top plate.

[0199] S7, collect displacement meter data without passive support and with passive support.

[0200] Calculate the absolute deformation of the roof: h (settlement deformation without support) and h' (settlement deformation with support).

[0201] Calculate the relative deformation Δh, Δh=h'-h.

[0202] The absolute deformation of each monitoring point is summarized and a deformation distribution map is drawn.

[0203] Compare the relative deformation under conditions without passive support and with passive support to determine the top control range of the support.

[0204] A reasonable deformation threshold (such as 20 mm) is set, and the area exceeding the threshold is determined as the top control range of the unit support.

[0205] Experimental data example

[0206]

[0207] Through comparative analysis, it can be concluded that under passive support conditions, the deformation of the tunnel roof is significantly reduced, indicating that passive support effectively controls the sinking deformation of the roof. According to the set deformation threshold, the support top control range is determined to be the area where the relative deformation exceeds 20 mm, which provides an important reference for tunnel support design.

[0208] like Figure 13 As shown, the actual top control area of ​​the unit bracket is drawn based on the on-site measured data. The top control effect of the unit bracket within the S1 range is good, and the top control effect of the unit bracket within the S2 range is average. It is considered that the range of S2 is the effective top control area of ​​the unit bracket.

[0209] According to the above theoretical calculations, the transportation gateway in the working face is vulnerable to the impact of the repeated rotation and migration of the overlying strata in the stope on the roadway, resulting in a reduction in the support strength of the support body. Therefore, it is still necessary to strengthen the support and monitoring and early warning work in the strong impact hazard area, and strengthen the prevention in the advanced section of the mining roadway. Measures such as adding advanced unit supports should be taken to carry out support reinforcement work.

[0210] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for measuring the roof control range of a unit support in the ultra-advanced mining roadway, characterized in that: It includes the following steps: S1. Along the roof strike and roof dip at the roadway roof, fiber Bragg grating displacement gauges are arranged to cover the contact surface between the unit support and the roadway roof. The fiber Bragg grating displacement gauges are electrically connected to a computer and transmit monitoring data to the computer. S2. A measurement fiber segment is set on the fiber Bragg grating displacement gauge, and the measurement fiber segment includes the maximum subsidence point of the settlement deformation of the roadway roof. S3. Calculate the overall deformation height of the measurement fiber segment under the conditions of having and not having the unit support controlling the roof respectively. The steps are as follows: S301. When there is a unit support controlling the roof, the measurement fiber segment is evenly divided into N fiber intervals at equal distances, and each fiber interval is evenly divided into n fiber units. The calculation formula for the overall deformation height of the measurement fiber segment is as follows: In the formula, h is the overall deformation height of the optical fiber section measured under the control of the unit support; L AB is the initial length of the optical fiber section under the control of the unit support; ε i is the uniform optical fiber strain of the optical fiber unit under the control of the unit support; n is the number of optical fiber units under the control of the unit support; d is the length of the optical fiber unit under the control of the unit support; N is the number of optical fiber sections under the control of the unit support; S302. When there is no unit support controlling the roof, the measurement fiber segment is evenly divided into N' fiber intervals at equal distances, and each fiber interval is evenly divided into n' fiber units. The calculation formula for the overall deformation height of the measurement fiber segment is as follows: In the formula, h' is the overall deformation height of the fiber optic segment measured under the condition of roof control without unit supports; L OP is the initial length of the fiber optic interval under the condition of roof control without unit supports; ε' i is the uniform strain of the optical fiber of the fiber optic unit under the condition of roof control without unit supports; n' is the number of fiber optic units under the condition of roof control without unit supports; d' is the length of the fiber optic unit under the condition of roof control without unit supports; N' is the number of fiber optic intervals under the condition of roof control without unit supports; S4. Calculate the relative deformation amount of fiber settlement with and without the unit support. The formula is: Δh = h′ - h In the formula, Δh is the relative deformation amount of fiber settlement with and without the unit support; h' is the overall deformation height of the fiber under the condition of no unit support controlling the roof; h is the overall deformation height of the fiber under the condition of having a unit support controlling the roof. S5. Draw a plane coordinate diagram of the roadway roof after arranging the fiber Bragg grating displacement gauges in the computer, and mark the coordinates of the relative deformation amount of fiber settlement of the fiber Bragg grating displacement gauges in the plane coordinate diagram. The covered area formed by connecting the coordinates of the relative deformation amount of fiber settlement in sequence is the roof control range of the unit support.

2. The method for measuring the roof control range of the unit support in the ultra-advanced extraction roadway according to claim 1, characterized in that, The measurement method further includes: Step S6, obtaining the stress change of the roadway roof within the roof control range of the unit support; the stress of the roadway roof = fiber strain * medium elastic modulus, where the medium elastic modulus is obtained by measuring through a uniaxial compression deformation experiment, and the fiber strain is obtained by calculating the settlement height of any section of the fiber. The calculation formula for the settlement height of any section of the fiber is: In the formula, h x-1,x is the settlement height of any optical fiber segment with unit support roof control; h' x-1,x is the settlement height of any optical fiber segment without unit support roof control; x is any fixed point where the optical fiber branches out; L AB is the initial length of the optical fiber interval under unit support roof control; L OP is the initial length of the optical fiber interval without unit support roof control; ε AB is the uniform strain of the optical fiber in the optical fiber interval under unit support roof control; ε OP is the uniform strain of the optical fiber in the optical fiber interval without unit support roof control.

3. A method for measuring the roof control range of the unit support in the ultra-advanced mining roadway according to claim 1, characterized in that, The method for setting the measurement fiber segment on the fiber Bragg grating displacement gauge is: Set two fixed points on the fiber arranged along the roadway axis or roadway dip. The fiber segment between the two fixed points is the measurement fiber segment, and the measurement fiber segment includes the maximum subsidence point formed by the settlement of the roadway roof under load.

4. A method for measuring the roof control range of the unit support in the ultra-advanced mining roadway according to any one of claims 1-3, characterized in that, A plurality of fiber Bragg grating displacement gauges are set, and their layout method is: On the rectangular dip side of the contact surface, several fiber Bragg grating displacement gauges of equal length are respectively arranged on both sides at a standard interval with its edge as the reference; on the rectangular strike side of the contact surface, several fiber Bragg grating displacement gauges of equal length are also respectively arranged on both sides at a standard interval with its edge as the reference.

5. A method for measuring the roof control range of the ultra-advanced mining roadway unit support according to any one of claims 1-3, characterized in that, The fiber Bragg grating displacement gauges are arranged on the roadway roof by drilling. The drilling width is set to 2 cm - 3 cm, and the drilling depth is set to 20 cm - 50 cm.

6. The method for measuring the roof control range of the unit support in the ultra-advanced mining roadway according to claim 5, wherein, After the fiber Bragg grating displacement gauges are arranged, a medium material is used for hole sealing of the drilling; taking the elastic modulus as the comparison standard, the difference ratio between the medium material and the roadway roof rock formation after solidification is less than 5%.

7. A method for measuring the roof control range of the unit support in the ultra-advanced extraction roadway according to claim 4, characterized in that A drilling device is used for drilling operations; The drilling device includes a horizontal directional drill and a grouting chamber fixedly arranged at the tail end of the drill bit of the horizontal directional drill; The horizontal directional drill is provided with a hollow drill pipe, and the hollow drill pipe penetrates through the grouting chamber; A stirring mechanism is arranged on the outer surface of the hollow drill pipe, and the stirring mechanism is composed of a plurality of fan blades arranged at intervals on the outer surface of the hollow drill pipe; the stirring mechanism is arranged inside the grouting chamber; The hollow drill pipe is provided with slurry outlet holes, and the slurry outlet holes are arranged near the tail end of the drill bit of the horizontal directional drill; an optical fiber is fixedly connected to the tail end of the grouting chamber.

8. The method for measuring the roof control range of the ultra-foresection mining roadway unit support according to claim 7, wherein A centralizer is arranged inside the horizontal directional drill, and the centralizer is used to provide support and guidance for the drilling operation of the rock-breaking roller bit; The horizontal directional drill is further provided with an expanding rock roller bit, and the expanding rock roller bit is arranged at the tail end of the rock-breaking roller bit and rotates synchronously with the rock-breaking roller bit for expanding the diameter of the drilled hole; A laser alignment instrument is further arranged inside the horizontal directional drill for realizing real-time direction and position monitoring during the drilling process.

9. A method for measuring the roof control range of the unit support in the ultra-advanced extraction roadway according to claim 8, characterized in that A limiting plate is further arranged inside the grouting chamber, and the limiting plate is arranged near the slurry outlet holes of the hollow drill pipe for controlling the concrete flow rate inside the buried unit bin.

10. A method for measuring the roof control range of the unit support in the ultra-advanced extraction roadway according to claim 8, characterized in that, The horizontal directional drill is provided with a rock-breaking roller bit, and the rock-breaking roller bit is arranged in a conical shape and conical teeth are arranged on its outer surface.

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