CN115717529B - Method for evaluating construction effect of protective layer in coal seam - Google Patents

Abstract

The invention provides a method for evaluating the construction effect of a protective layer in a coal seam, which comprises the following steps: s1, measuring gas parameters of a single outburst coal seam; s2, arranging a plurality of groups of investigation holes in a coal seam floor rock roadway towards a coal seam, and measuring the coal unloading quantity of the investigation holes and the expansion deformation quantity of surrounding coal bodies; s3, determining an effective control range corresponding to the investigation holes on the basis that the expansion deformation of the coal body around the investigation holes is more than or equal to 3 per mill, and determining coal unloading indexes of the inner protection layer, the measure holes and the measure hole units; s4, implementing coal unloading measures according to unit coal unloading indexes of the measure holes, and accurately measuring the coal unloading amount of each measure hole; s5, calculating accumulated coal unloading quantity of the measure holes, and judging whether the effectiveness of the measure meets the standard; s6, after the implementation of the coal unloading measures is finished, dividing rectangular units, and detecting whether a pressure relief blank area exists in a coal bed in the rectangular units; s7, judging the protection effect of the protective layer in the coal layer; and if the pressure relief blank area does not exist, judging that the protection effect of the protective layer in the coal layer reaches the standard.

Description

A method for evaluating the construction effect of protective layer in coal seam

technical field

The invention relates to the technical field of coal mine gas control, in particular to a method for evaluating the construction effect of a protective layer in a coal seam, which is suitable for the regional control of gas in a single outburst thick coal seam.

Background technique

my country's coal-bearing rock series have complex structures, diverse shapes, poor air permeability, and frequent coal and gas outburst accidents, which seriously restrict the safe and efficient mining of coal mines. The provisions of the "Coal Mine Safety Regulations" and a large number of engineering practices have shown that the mining of protective layers can change the stress environment of coal and rock, release the accumulated elastic energy, destroy the surrounding rock structure, etc. The mechanical strength of the coal seam is increased, and the risk of coal seam outburst can be eliminated or reduced.

However, protection seam mining has its specific applicability conditions. It has good safety and economic benefits for coal seam groups with close distances, especially coal seams with no outburst dangerous coal seams. However, most mines can only choose adjacent unminable coal seams. Layers or rock formations are used as protective layers, and the method of coal and rock simultaneous mining is used to implement protective layer mining. Especially for some single outburst thick coal seams or coal seam groups with short-distance first mining outburst coal seams, due to the hard roof and floor strata or serious water inrush risks, they do not have good mining conditions, and the upper/lower protective layer relationship cannot be formed. The measure of coal seam gas pre-extraction through seam or through-bed drilling is used for gas control, and the test of the control effect of the measures is carried out by testing the residual gas content or pressure index of the coal seam. Due to the limited control range of borehole drainage, outburst elimination is mainly achieved by reducing the coal seam gas pressure in the drainage area, and the effect is significantly different from that of the protection layer mining technology.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a safe, reliable, and highly applicable method for evaluating the construction effect of the protective layer in the coal seam. The present invention aims at the distribution characteristics of a single coal seam and combines drilling, punching, cutting and expansion. The combined coal unloading measures form an inner protective layer in a certain layer of the coal seam or between adjacent drill holes, so as to promote the pressure relief of the remaining coal body in the coal seam and eliminate the power of outburst.

In order to achieve the above object, technical scheme of the present invention is:

A method for evaluating the construction effect of a protective layer in a coal seam, comprising the following steps:

S1, the original gas content, the original gas pressure, the average thickness of the coal seam, and the firmness coefficient of different layers of the coal seam are measured by the method of drilling through the seam;

Among them, the determination of the solidity coefficient of coal is determined according to "Measurement Methods for Physical and Mechanical Properties of Coal and Rock Part 12: Determination Method for Coal Solidity Coefficient" (GB/T 23561.12-2010).

S2, set multiple groups of investigation holes in the rocky roadway of the coal seam floor to the coal seam, implement coal unloading measures of different scales in each group of inspection holes, accurately measure the amount of coal unloaded at each inspection hole, and measure the expansion and deformation of the coal body around the inspection hole;

S3, based on the expansion and deformation of the coal body around the inspection hole ≥ 3‰, determine the effective control range corresponding to the inspection hole, and combine the coal seam mining face layout characteristics and replacement needs to separate the coal seam from the inner protective layer, and determine the Inner protective layer, measure holes, unit unloading indicators of measure holes;

S4. Implement coal unloading measures according to the coal unloading index of the measure hole unit, and accurately measure the coal unloading amount of each measure hole; When the amount of coal is less than the coal unloading index of the unit, the measure hole will continue to implement the coal unloading measure;

S5, calculate the cumulative coal unloading amount of the measure hole, and determine whether the effectiveness of the measure is up to the standard; if it is up to the standard, proceed to step S6; if it is not up to the standard, then repeat step S4, that is, in the adjacent measure hole whose coal unloading amount does not reach the unit unloading index Continue to implement coal unloading measures during the period;

S6, after the coal unloading measures are implemented, divide the control area of the measure hole into 30m×30m rectangular units, and use the inter-hole pit penetration detection method to detect whether there is a blank area for pressure relief in the coal seam in the rectangular unit;

S7, determine the protection effect of the protective layer in the coal seam; if there is no pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is up to the standard, and proceed to step S8; if there is a pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is not up to standard, Repeat step S4, and continue to implement coal unloading measures in the blank area of pressure relief;

S8, the effect test of the inner protective layer measures. After all the boreholes within the test range have no negative pressure, the gas pressure and gas content of the boreholes are measured according to the procedure.

As an improvement to the above-mentioned technical solution, the inspection hole is arranged in the floor rock roadway according to the inspection requirements, and is arranged vertically to the center line of the roadway, and one or more than one row of multiple fan-shaped drilled holes are arranged. The hole position is not less than 0.5m through the roof of the coal seam, and each group of inspection holes is spaced at 20m to avoid cross influence.

As an improvement to the above-mentioned technical scheme, the coal unloading measures of the inspection hole or the measure hole, including but not limited to the coal unloading measures using hydraulic punching, slotting, and mechanical reaming; using hydraulic or mechanical power to destroy the integrity of the coal seam, And the broken coal body is discharged from the investigation hole or measure hole, and a certain shape of hole (inner protective layer) is formed in the coal seam to achieve the purpose of providing expansion and deformation space for the remaining coal body in the area controlled by the inspection hole or measure hole.

As an improvement to the above-mentioned technical scheme, the hole (inner protective layer) refers to the continuous hole (inner protective layer) formed parallel to the coal seam after the continuous unloading of the coal body with a smaller firmness coefficient in the coal seam. layer) (as shown in Figure 2); or refers to multiple independent or partially independent holes (inner protective layer) that are orthogonal or oblique to the coal seam (as shown in Figure 3).

As an improvement to the above-mentioned technical solution, the different scales described in step S2 are divided according to the amount of coal unloading in a survey hole, and the coal unloading measures divided are implemented with different intensities, and each survey hole in the same group implements coal unloading measures of the same scale .

As an improvement to the above technical solution, the amount of coal unloaded in step S2 is the quality of the coal body unloaded from the survey hole after coal unloading measures are taken in the survey hole.

As an improvement to the above technical solution, the measurement of expansion and deformation in step S2 refers to installing multiple sets of horizon locators within the range of 5m to 10m on both sides of the investigation hole in advance, and each set of horizon locators is installed along the centerline of the floor rock roadway. They are arranged at intervals of 1m, and the coal seam roof, coal seam floor, and coal seam layer deformation before and after coal unloading measures are implemented in the investigation hole are monitored respectively.

As an improvement to the above-mentioned technical solution, the effective control range described in step S3 is a circle with the center of the investigation hole and the minimum distance from the position where the expansion and deformation of the coal body around the inspection hole is greater than or equal to 3‰ to the center of the inspection hole as the radius the range covered.

As an improvement to the above-mentioned technical scheme, the measure hole described in step S3 is arranged in the floor rock roadway according to the need for coal seam gas control, and is perpendicular to the center line of the roadway, with multiple rows of fan-shaped drilled holes. The measure hole should pass through The roof of the coal seam shall not be less than 0.5m, and the maximum distance between adjacent measure holes shall not be greater than twice the effective control range of the coal unloading index of the corresponding unit, and ensure that there is no control blank area between adjacent measure holes.

As an improvement to the above-mentioned technical scheme, the unit coal unloading index described in step S3, the minimum coal unloading amount of the unit coal hole section length of the measure hole that conforms to the measure hole design spacing, taking the present invention as an example, is determined to be the coal section 1m of the measure hole coal section that should be unloaded The coal output is 0.5t, that is, the unit unloading coal index is 0.5t/m (coal hole section).

As an improvement to the above technical solution, the formula for determining the effectiveness of the measures described in step S5 is:

_Ctotal ≥ n·C, where _Ctotal is the accumulative coal unloading quantity of the measure hole, the unit is t; n is the number of measure hole; C is the unit unloading coal index, the unit is t;

As an improvement to the above-mentioned technical solution, the formula for calculating the accumulated coal unloading amount described in step S5 is:

C _total = C ₁ +C ₂ +C ₃ +...+C _n , where C ₁ is the coal unloading amount of the first measure hole, unit is t; C ₂ is the coal unloading amount of the second measure hole, unit is t; C _n is the coal unloading capacity of the nth measure hole, the unit is t.

As an improvement to the above-mentioned technical solution, the pit penetration detection method between holes described in step S6 uses a fixed-point detection method to measure the hole on the edge of the rectangular unit, fixed-point transmission, and multi-point reception: that is, in the two measuring tracks (the left edge of the rectangular unit The measuring hole and the right edge measuring hole) respectively install the transmitting probe and the receiving probe, and the high-frequency radio wave signal sent by the transmitting probe at the same point is received by the receiving probe at the corresponding point of the other measuring track (fan-shaped receiving), alternately change the position of the transmitting probe and the receiving probe, and after performing all the detection of the rectangular unit coal seam between the two relative measuring tracks, cross-draw and circle the internal pressure relief blank area of the rectangular unit coal seam. Then complete the hole penetration detection of each rectangular unit in the same way.

As an improvement to the above-mentioned technical solution, the relative positions of the transmitting probe and the receiving probe in the coal seam are the points described in step S6. Taking the present invention as an example, the points of the transmitting probe and the receiving probe are the position of the coal seam roof, In the middle of the coal seam, the bottom of the coal seam, and during the implementation of hole penetration detection between holes, the positions of the transmitting probe and the receiving probe should be consistent, that is, they should be at the top of the coal seam or at the bottom of the coal seam at the same time.

As an improvement to the above-mentioned technical solution, after the inner protective layer described in steps S3 and S7 is mined compared with the interlayer protective layer (upper protective layer, lower protective layer), the protected layer is promoted to expand and deform, and the power of outburst is eliminated, and the coal seam The inner protective layer is to implement coal unloading measures inside the coal seam to provide expansion and deformation space for the remaining coal body in the same coal seam, so as to achieve the purpose of eliminating the power of outburst in the coal seam.

Compared with prior art, the advantages and positive effects that the present invention has are:

The present invention proposes a method for evaluating the construction effect of a protective layer in a coal seam that is safe, reliable and highly applicable. Aiming at the distribution characteristics of a single coal seam, a composite coal unloading measure combined with drilling, punching, cutting, and expansion can be used in a certain layer or adjacent to the coal seam. An inner protective layer is formed between the boreholes to promote the pressure relief of the remaining coal in the coal seam and eliminate the outburst power; use the layer locator to monitor the expansion and deformation of the coal seam before and after the coal unloading measures, and investigate the effective control range of the coal unloading measures and the unit unloading indicators. Provide a basis for the parameter design of coal unloading measures; use inter-hole pit penetration to detect the blank area of pressure relief, evaluate the protection effect of the protective layer in the coal seam, and further improve the reliability of the measures.

Compared with the mining of conventional interlayer protective layers (upper/lower protective layers), the applicability and reliability of the measures have been improved, and the problem of safe mining of outburst coal seams with single outburst thick coal seams or close coal seam groups has been solved. A gas control model that relies solely on drainage to eliminate outbursts has been established, which has effectively improved the coal seam pressure relief effect and shortened the gas control cycle.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the specific flowchart of the implementation method of the present invention;

Fig. 2a and Fig. 2b are schematic diagrams of unloading and depressurization of the protective layer in the outburst coal seam (continuous holes parallel to the coal seam (inner protective layer)); among them, Fig. 2a is formed before pressure relief, and Fig. 2b is formed after pressure relief;

Fig. 3a and Fig. 3b are the schematic diagrams of unloading and depressurizing the inner protective layer of the outburst coal seam (forming orthogonal or oblique holes (inner protective layer) with the coal seam); among them, Fig. 3a is formed before pressure relief, and Fig. 3b is after pressure relief. Forming;

Figure 4 Schematic diagram of measure hole layout and rectangular unit division;

Figure 5a, Figure 5b, and Figure 5c are schematic diagrams of the connection of the inter-hole pit penetration detection device; among them, Figure 5a is a connection schematic diagram of the connection of the inter-hole pit penetration detection device at the position of the coal seam roof, and Figure 5b is the connection diagram of the inter-hole pit penetration detection device at the point and position of the coal seam middle Connection schematic diagram, Fig. 5c is the connection schematic diagram of the pit penetration detection device between holes at the position of the coal seam floor;

Fig. 6a, Fig. 6b, Fig. 6c, Fig. 6d, Fig. 6e, Fig. 6f are schematic diagrams of the implementation process of pit penetration detection between holes; Fig. 6a is a diagram of the relative position relationship of pit penetration detection between holes, and Fig. 6b is a point hole at the position of the coal seam roof Inter-pit penetration detection map, Fig. 6c is the detection map of inter-hole pit penetration in the middle of the coal seam, Fig. 6d is the detection map of inter-hole pit penetration in the coal seam floor position, Fig. 6e is the detection map of inter-hole pit penetration in all points, Fig. 6f is a diagram of the alternate transformation process of pit penetration detection between holes.

Among them, 1 is the state of the coal seam before pressure relief; 2 is the stress distribution of the coal seam before pressure relief; 3 is the measure hole, 4 is the inner protective layer, 5 is the state of the coal seam after pressure relief, 6 is the stress distribution of the coal seam after pressure relief, and 7 is the coal seam Roof, 8 is the coal seam, 9 is the rectangular unit, 10 is the edge of the rectangular unit, 11 is the blank area for pressure relief, 12 is the floor rock roadway, 13 is the launching probe, 14 is the receiving probe, 15 is the cable, 16 is the detection Host, 17 is the field strength ray.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention Inside.

As shown in Figure 1, this embodiment discloses a method for evaluating the construction effect of a protective layer in a coal seam, including the following steps:

S1, the original gas content, the original gas pressure, the average thickness of the coal seam, and the firmness coefficient of different layers of the coal seam are measured by the method of drilling through the seam;

Among them, the determination of the solidity coefficient of coal is determined according to "Measurement Methods for Physical and Mechanical Properties of Coal and Rock Part 12: Determination Method for Coal Solidity Coefficient" (GB/T 23561.12-2010).

S2, set multiple groups of investigation holes in the rocky roadway of the coal seam floor to the coal seam, implement coal unloading measures of different scales in each group of inspection holes, accurately measure the amount of coal unloaded at each inspection hole, and measure the expansion and deformation of the coal body around the inspection hole;

S3, based on the expansion and deformation of the coal body around the inspection hole ≥ 3‰, determine the effective control range corresponding to the inspection hole, and combine the coal seam mining face layout characteristics and replacement needs to separate the coal seam from the inner protective layer, and determine the Inner protective layer, measure holes, unit unloading indicators of measure holes;

S4. Implement coal unloading measures according to the coal unloading index of the measure hole unit, and accurately measure the coal unloading amount of each measure hole; When the amount of coal is less than the coal unloading index of the unit, the measure hole will continue to implement the coal unloading measure;

S5, calculate the cumulative coal unloading amount of the measure hole, and determine whether the effectiveness of the measure is up to the standard; if it is up to the standard, proceed to step S6; if it is not up to the standard, then repeat step S4, that is, in the adjacent measure hole whose coal unloading amount does not reach the unit unloading index Continue to implement coal unloading measures during the period;

S6, after the coal unloading measures are implemented, divide the control area of the measure hole into 30m×30m rectangular units, and use the inter-hole pit penetration detection method to detect whether there is a blank area for pressure relief in the coal seam in the rectangular unit;

S7, determine the protection effect of the protective layer in the coal seam; if there is no pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is up to the standard, and proceed to step S8; if there is a pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is not up to standard, Repeat step S4, and continue to implement coal unloading measures in the blank area of pressure relief;

S8, the effect test of the inner protective layer measures. After all the boreholes within the test range have no negative pressure, the gas pressure and gas content of the boreholes are measured according to the procedure.

As shown in Figure 2a, Figure 2b, Figure 3a, and Figure 3b, the coal unloading measure described in step S2 uses hydraulic or mechanical power to destroy the integrity of the coal seam, and unloads the broken coal body through the measure hole 3, forming a coal seam within the coal seam. Inner protective layer 4, that is, multiple independent or partially independent holes that are orthogonal or oblique to the coal seam (inner protective layer 4 in Figure 3a) are formed around the coal unloading measure hole 3, providing horizontal expansion and deformation space for the remaining coal body in the coal seam , or form continuous pores parallel to the coal seam (protective layer 4 in Fig. 2a), providing vertical expansion and deformation space for the remaining coal body in the coal seam, so that the coal body gradually creeps and deforms, and the occurrence form changes from the state 1 before the pressure relief of the coal seam to the coal seam State 5 after decompression, while the stress distribution 2 before decompression of the coal seam decreases synchronously and tends to be uniform, finally forming the stress distribution 6 after decompression of the coal seam.

As shown in Figure 4, in step S3, the measure hole 3 is arranged in the floor rock roadway 12 according to the need for coal seam gas control, and is perpendicular to the center line of the roadway, with multiple rows of fan-shaped drilled holes, the measure hole 3 It should pass through the coal seam roof 7 by no less than 0.5m, and the maximum distance between adjacent measure holes should not be greater than twice the effective control range of the coal unloading index of the corresponding unit, and ensure that there is no control blank area between adjacent measure drill holes; The rectangular unit 9 described in S6 is a rectangle of 30m×30m divided by the coal seam 8 according to the control area of the measure hole 3, wherein the plane where the measure hole 3 on the edge of the rectangular unit 9 is the edge 10 of the rectangular unit, and there may be pressure relief in the control area of the measure hole 3 Blank area 11.

As shown in Fig. 5, the inter-hole pit penetration detection method described in step S6, the inter-hole pit penetration detection device includes a transmitting probe 13, a receiving probe 14, a cable 15, and a detection host 16, and one transmitting probe 13 is passed through The cable 15 is connected to the detection host 16 and sent into the measure hole 3. At the same time, multiple receiving probes 14 are respectively connected to the respective detection host 16 through the corresponding cables 15, and sent into the corresponding measure hole 3 in turn. . Then implement fixed-point detection, fixed-point emission, and multi-point reception: the transmitting probe 13 transmits high-frequency radio wave signals at fixed points on the coal seam roof, the middle of the coal seam, and the coal seam floor in turn, and multiple receiving probes 14 are sequentially synchronized in the corresponding positions. The high-frequency radio wave signal is received, and the high-frequency radio wave signal propagates and enters the receiving path, which is the field strength ray 17 .

As shown in Fig. 6, in step S6 described in step S6, the implementation process of pit penetration detection between holes uses the measure hole 3 in the edge 10 of the rectangular unit on one side as the measurement track one, and the rectangular unit on the other side of the rectangular unit 9 parallel to it. The measure hole 3 in the edge 10 serves as track two. According to the connection method of the inter-hole pit penetration detection device shown in Figure 4, the transmitting probe 13 and the receiving probe 14 are respectively connected to the corresponding cables 15 and the detection host 16 in sequence, and the transmitting probe 13 is sent into the first measuring track In the first measure hole 3, a plurality of receiving probes 14 are respectively sent into each measure hole 3 in the second measuring track.

In the first step, the transmitting probe 13 transmits high-frequency radio wave signals at fixed points on the coal seam roof, the middle of the coal seam, and the coal seam floor in the first measure hole 3 in the first measurement track, and multiple receiving probes in the second measurement track 14 Receive high-frequency radio wave signals sequentially and synchronously at corresponding points;

In the second step, the launch probe 13 is withdrawn from the first measure hole 3 in the test track one, and sent into the second measure hole 3 in the test track one, and the detection is carried out in the same order until the launch probe 13. Each measure hole 3 in the test track one is implemented to complete the detection;

The third step is to alternately change the positions of the transmitting probe 13 and the receiving probe 14 in the measuring track one and the measuring track two. High-frequency radio wave signals are transmitted sequentially in each measurement hole 3, and the high-frequency radio wave signals are received in a synchronous sector by the receiving probe 14 at corresponding points in the first measurement track, and finally complete the detection of all points;

In the fourth step, according to the detection results of all points, the blank area 11 for pressure relief inside the coal seam 8 in the rectangular unit 9 is drawn and circled. Then complete the hole penetration detection of each rectangular unit 9 in the same manner.

The inspection holes are arranged in the floor rock roadway according to the inspection needs, and are arranged vertically to the center line of the roadway. One or more than one row of piercing holes distributed in a fan shape, the position of the end hole of the inspection hole passes through the coal seam roof by no less than 0.5 m, and each group of investigation holes should be separated by 20m to avoid cross influence;

Coal unloading measures, including but not limited to coal unloading measures such as hydraulic punching, slotting, and mechanical reaming using survey holes; using hydraulic or mechanical power to destroy the integrity of the coal seam, and removing the broken coal body from the survey The hole is unloaded to form a certain shape of holes (inner protective layer) in the coal seam, so as to provide expansion and deformation space for the remaining coal body in the inspection hole control area;

Holes (inner protective layer), or refers to continuous holes (inner protective layer) parallel to the coal seam formed after the continuous unloading of coal bodies with small solidity coefficient layers in the coal seam (as shown in Figure 2); Or refers to irregular holes (inner protective layer) that are multiple independent or partially independent, orthogonal or oblique to the coal seam (as shown in Figure 3);

Different scales, according to the amount of coal unloading in a survey hole, the divided coal unloading measures are implemented with different intensities, and each survey hole in the same group implements the same scale of coal unloading measures; Finally, the quality of the coal body is unloaded from the investigation hole; the measurement of expansion and deformation refers to the installation of multiple sets of horizon locators within the range of 5m~10m on both sides of the investigation hole in advance, and each set of horizon locators along the centerline of the floor rock roadway Arranged at intervals of 1m, and separately monitor the coal seam roof, coal seam floor, and coal seam layer deformation before and after the coal unloading measures are implemented in the investigation hole;

The effective control range is the area covered by a circle with the center of the survey hole and the minimum distance from the position where the expansion and deformation of the coal body around the survey hole is greater than or equal to 3‰ to the center of the survey hole as the radius;

Measure holes, according to the needs of coal seam gas control, are arranged in the floor rock roadway, perpendicular to the center line of the roadway, and have multiple rows of fan-shaped drilling holes. The maximum hole spacing should not be greater than twice the effective control range of the coal unloading index of the corresponding unit, and ensure that there is no control blank area between adjacent drilling holes;

The coal unloading index per unit, the minimum coal unloading amount of the unit coal hole section length of the measure hole that meets the measure hole design spacing, taking the present invention as an example, it is determined that the coal amount of 0.5t should be unloaded for 1m of the coal section of the measure hole, that is, the coal unloading index per unit is 0.5t/m (coal hole section).

The formula for judging the effectiveness of measures is:

_Ctotal ≥ n·C, where _Ctotal is the accumulative coal unloading quantity of the measure hole, the unit is t; n is the number of measure hole; C is the unit unloading coal index, the unit is t;

The formula for calculating the cumulative coal unloading volume is:

C _total = C ₁ +C ₂ +C ₃ +...+C _n , where C ₁ is the coal unloading amount of the first measure hole, unit is t; C ₂ is the coal unloading amount of the second measure hole, unit is t; C _n is the coal unloading capacity of the nth measure hole, the unit is t.

Hole hole penetration detection method, using the division of the measuring hole on the edge of the rectangular unit to implement fixed-point detection, fixed-point transmission, multi-point receiving: that is, install the Transmitting probe and receiving probe, the high-frequency radio wave signal sent by the transmitting probe at the same point is received by the receiving probe at the corresponding point of another measuring track (fan-shaped reception), and the transmitting probe and receiving probe are alternately changed After all detection is carried out on the rectangular unit coal seam between the two relative measuring tracks, the internal pressure relief blank area of the rectangular unit coal seam is cross-drawn. Then complete the hole penetration detection of each rectangular unit in the same way.

Points, the relative positions of the transmitting probe and the receiving probe in the coal seam. Taking the present invention as an example, the points of the transmitting probe and the receiving probe are the position of the coal seam roof, the middle position of the coal seam, the position of the coal seam floor, and the pit penetration between the holes. During the implementation of the detection, the positions of the transmitting probe and the receiving probe should be consistent, that is, at the top of the coal seam or at the bottom of the coal seam at the same time.

The protective layer in the coal seam, compared with the interlayer protective layer (upper protective layer, lower protective layer) after mining, promotes the expansion and deformation of the protected layer and eliminates the power of outburst. The inner protective layer of the coal seam is implemented in the coal seam. The remaining coal body in the same coal seam provides space for expansion and deformation, so as to achieve the purpose of eliminating the power of outburst in this coal seam.

Claims (10)

1. a protective layer construction effect evaluation method in a coal seam, is characterized in that: comprise the steps: S1, the original gas content, the original gas pressure, the average thickness of the coal seam, and the firmness coefficient of different layers of the coal seam are measured by the method of drilling through the seam; S2, set multiple groups of investigation holes in the rocky roadway of the coal seam floor to the coal seam, implement coal unloading measures of different scales in each group of inspection holes, accurately measure the amount of coal unloaded at each inspection hole, and measure the expansion and deformation of the coal body around the inspection hole; S3, based on the expansion and deformation of the coal body around the inspection hole ≥ 3‰, determine the effective control range corresponding to the inspection hole, and combine the coal seam mining face layout characteristics and replacement needs to determine the coal unloading index for the inner protective layer measures hole unit, Carry out measure hole parameter design; S4. Implement coal unloading measures according to the coal unloading index of the measure hole unit, and accurately measure the coal unloading amount of each measure hole; When the amount of coal is less than the coal unloading index of the unit, the measure hole will continue to implement the coal unloading measure; S5, calculate the cumulative coal unloading amount of the measure hole, and determine whether the effectiveness of the measure is up to the standard; if it is up to the standard, proceed to step S6; if it is not up to the standard, then repeat step S4, that is, in the adjacent measure hole whose coal unloading amount does not reach the unit unloading index Continue to implement coal unloading measures during the period; S6, after the coal unloading measures are implemented, divide the control area of the measure hole into 30m×30m rectangular units, and use the inter-hole pit penetration detection method to detect whether there is a blank area for pressure relief in the coal seam in the rectangular unit; S7, determine the protection effect of the protective layer in the coal seam; if there is no pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is up to the standard, and proceed to step S8; if there is a pressure relief blank area, it is determined that the protective layer protection effect in the coal seam is not up to standard, Repeat step S4, and continue to implement coal unloading measures in the blank area of pressure relief; S8, the effect test of the inner protective layer measures. After all the boreholes within the test range have no negative pressure, the gas pressure and gas content of the boreholes are measured according to the procedure. 2. The method for evaluating the construction effect of the protective layer in the coal seam as claimed in claim 1, characterized in that: the inspection holes are arranged in the floor rock roadway according to the inspection requirements, arranged vertically to the center line of the roadway, and arranged in one or more rows. For the fan-shaped distribution of drilling holes, the position of the end hole of the investigation hole passes through the coal seam roof by no less than 0.5m, and the interval of each group of inspection holes is 20m to avoid cross influence. 3. As claimed in claim 1, the construction effect evaluation method of the protective layer in the coal seam is characterized in that: the coal unloading measures of the investigation hole or the measure hole include but are not limited to the unloading measures utilizing hydraulic punching, slotting, and mechanical reaming. Coal measures: use hydraulic or mechanical power to destroy the integrity of the coal seam, and unload the broken coal body from the inspection hole or measure hole, forming a certain shape of hole in the coal seam, that is, the inner protective layer, so as to achieve the control area of the inspection hole or measure hole The purpose of remaining coal body is to provide space for expansion and deformation. 4. As claimed in claim 3, the construction effect evaluation method of the inner protective layer of the coal seam is characterized in that: the inner protective layer, or refers to the parallel formation formed after the continuous unloading of coal bodies with smaller solidity coefficient layers in the coal seam. Continuous pores in the coal seam; or multiple independent or partially independent pores that are orthogonal or oblique to the coal seam. 5. The method for evaluating the construction effect of the protective layer in the coal seam as claimed in claim 1, characterized in that: the measurement of the amount of expansion and deformation in step S2 refers to the installation of multiple groups of horizon locators within the range of 5m to 10m on both sides of the investigation hole in advance , each group of layer locators is arranged along the centerline of the floor rock roadway at intervals of 1m, and monitors the layer deformation of the coal seam roof, coal seam floor, and coal seam before and after coal unloading measures are implemented in the investigation hole. 6. As claimed in claim 1, the construction effect evaluation method of the protective layer in the coal seam is characterized in that: the effective control range described in the step S3 is centered on the inspection hole, and the expansion and deformation of the coal body around the inspection hole is greater than or equal to 3 The range covered by a circle whose minimum distance from the position of ‰ to the center of the survey hole is the radius. 7. The evaluation method for the construction effect of the protective layer in the coal seam as claimed in claim 1, characterized in that: the measure holes described in step S3 are arranged in the floor rock roadway according to the coal seam gas control requirements, perpendicular to the roadway centerline, and arranged in multiple rows in the form of For fan-shaped distributed drilling holes, the measure holes should pass through the coal seam roof by no less than 0.5m, and the maximum distance between adjacent measure holes should not be greater than twice the effective control range of the coal discharge index of the corresponding unit, and ensure that adjacent measure holes There is no control void between the wells. 8. As claimed in claim 1, the evaluation method for the construction effect of the protective layer in the coal seam is characterized in that: in the step S3, the coal unloading index per unit, the minimum coal unloading amount of the unit coal hole section length of the measure hole that meets the measure hole design spacing, is determined as the measure 0.5t of coal should be unloaded in 1m of the hole coal section, that is, the unit unloading coal index is 0.5t/m. 9. As claimed in claim 1, the construction effect evaluation method of the protective layer in the coal seam is characterized in that: the formula for determining the effectiveness of measures in step S5 is: _Ctotal ≥ n·C, where _Ctotal is the accumulative coal unloading quantity of the measure hole, the unit is t; n is the number of measure hole; C is the unit unloading coal index, the unit is t; The formula for calculating the cumulative coal unloading volume is: C _total = C ₁ +C ₂ +C ₃ +...+C _n , where C ₁ is the coal unloading amount of the first measure hole, unit is t; C ₂ is the coal unloading amount of the second measure hole, unit is t; C _n is the coal unloading capacity of the nth measure hole, the unit is t. 10. as claimed in claim 1, the construction effect evaluation method of the protective layer in the coal seam is characterized in that: the hole penetration detection method between the holes utilizes the fixed-point detection method to implement the fixed-point detection method by dividing the edge measure hole of the rectangular unit, fixed-point emission, and multi-point reception: that is, in two A transmitting probe and a receiving probe are respectively installed in each measuring track. The high-frequency radio wave signal sent by the transmitting probe at the same point is received by the receiving probe at the corresponding point of the other measuring track, and the transmitting probe and receiving probe are alternately changed. The location of the probe tube, after all the detection of the rectangular unit coal seam between the two opposite measuring tracks, cross-draw to circle the internal pressure relief blank area of the rectangular unit coal seam; then complete the inter-hole pit penetration of each rectangular unit in the same way probing.

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