A ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone

Abstract

The present invention relates to the technical field of coal mine roadway disaster control, and particularly relates to a ground advanced exploration and control method for a coal mine roadway passing through a fault zone. The method includes: arranging a ground drill site and designing a ground directional borehole structure and a borehole trajectory; the ground directional borehole structure includes a first-opening straight hole section, a second-opening deflecting section, and a third-opening branching section; calculating the designed reinforcement range; at the ground drill site, drilling holes according to the ground directional borehole structure and the borehole trajectory, and the drilling operation of the first-opening straight hole section includes drilling, casing lowering, pipe solidification, and pressure testing; calculating the grouting volume according to the designed reinforcement range, and grouting in the third-opening branching section according to the grouting volume; conducting well logging during the drilling process of the second-opening deflecting section and the third-opening branching section to obtain well logging data; evaluating the grouting effect and conducting hole sealing operations. The present invention reinforces the surrounding rock mass of the roadway through ground directional boreholes before the underground roadway excavation, with less interference with underground operations, improving production efficiency and coal mining safety.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine roadway disaster control, and specifically relates to a ground advance exploration and control method for a coal mine roadway passing through a fault zone. Background Art

[0002] The fault zone is a common bad geological body in the coal-bearing strata. Its rock mass is broken, stress is concentrated, and water-conducting fissures are connected. Under mining disturbance, it is a high-risk area for disaster accidents such as water inrush, roof fall, rock burst, and mine tremor. Under normal processes, when a roadway crosses a fault zone, the support difficulty is great, the operation risk is high, and the later maintenance is difficult.

[0003] The existing technologies mainly cover the roadway to pass through the fault zone by strengthening the support and injecting grout into the underground surrounding rock or a combination of both. Strengthening the support inevitably increases the construction difficulty and prolongs the construction period, affecting the production efficiency; injecting grout into the underground surrounding rock is limited by the underground operation space, with small grouting pressure, short grouting section, small grouting volume, and limited reinforcement range. There are significant limitations especially in the treatment of large fault zones. At the same time, before the treatment of the fault zone is completed by the existing methods, manual construction is required within the disaster-affected range of the underground fault zone. The personnel operation environment is poor, and high requirements are imposed on construction safety guarantee measures. The existing technologies have defects such as great construction difficulty, long construction period, limited reinforcement range, and poor operation safety. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a ground advance exploration and control method for a coal mine roadway passing through a fault zone, and the specific technical solution adopted is as follows:

[0005] An embodiment of the present invention provides a ground advance exploration and control method for a coal mine roadway passing through a fault zone:

[0006] Arrange a ground drill field, and design the structure and trajectory of the ground directional boreholes; the structure of the ground directional boreholes includes a first open vertical hole section, a second open inclined hole section, and a third open branch section; calculate and design the reinforcement range;

[0007] At the ground drill field, drill boreholes according to the structure and trajectory of the ground directional boreholes. The drilling operation of the first open vertical hole section includes drilling, casing lowering, pipe solidification, and pressure testing; calculate the grouting volume according to the designed reinforcement range, and perform grouting in the third open branch section according to the grouting volume;

[0008] During the drilling process of the second open inclined hole section and the third open branch section, logging is carried out to obtain logging data, and the data is sorted out and summarized; evaluate the grouting effect and perform hole sealing operations.

[0009] Preferably, arranging the ground drill field includes: when the roadway passing through the fault has an inclination angle, the ground drill field is set on the side with a higher roadway elevation.

[0010] Preferably, the drilling trajectory is designed, including: designing the drilling trajectory using compass professional software.

[0011] Preferably, the first open vertical hole section, the second open deviated hole section, and the third open branch hole section include:

[0012] The first open vertical hole section is connected to the second open deviated hole section, and the second open deviated hole section is connected to the third open branch hole section; the third open branch hole section has 4 branch holes, namely the roof hole, the right rib hole, the floor hole, and the left rib hole; the roof hole is located directly above the roadway, the right rib hole is located on the right rib of the roadway, the floor hole is located directly below the roadway, and the left rib hole is located on the left rib of the roadway.

[0013] Preferably, the calculation formula for the designed reinforcement range is:

[0014]

[0015] Wherein, R is the radius of the plastic zone, that is, the designed reinforcement range; r 1 is the equivalent radius of the roadway; H is the depth of the roadway burial; γ is the average unit weight of the stratum; C is the cohesion of the surrounding rock; is the internal friction angle.

[0016] Preferably, drilling is carried out according to the surface orientation drilling structure and the drilling trajectory, including:

[0017] Drilling in the first open vertical hole section, lowering the first open casing, cementing the first open casing, and pressure testing; drilling in the second open deviated hole section, lowering the second open casing, cementing the second open casing, and pressure testing, and mud logging is carried out during drilling; segmental drilling in the third open branch hole section, and forward-stage grouting;

[0018] The first open casing passes through the surface soil layer and enters the bedrock or stable stratum, and the second open casing reaches the target horizon; the casing cementing includes: circulating the drilling fluid to ensure the connectivity between the outer annulus of the casing and the inside of the casing, lowering the casing to the designed position, injecting single-fluid cement slurry into the casing for well cementing until the cement returns to the ground from the annular space outside the casing, and completing the casing cementing;

[0019] When carrying out segmental drilling in the third open branch hole section, it is necessary to calculate the drilling depth of each branch section in the third open, and the calculation formula is:

[0020]

[0021] Wherein, h is the drilling depth of each branch section, M is the coal seam thickness or mining height, P is the water head pressure, K p is the tensile strength of the coal, and K is the safety factor.

[0022] Preferably, the grouting volume is calculated according to the designed reinforcement range, and grouting is carried out in the third open branch hole section according to the grouting volume, including:

[0023] Construct geometric relationships based on the layout positions of the branch holes, and combine with the designed reinforcement range to obtain the slurry diffusion radius; calculate the grouting volume of each branch hole, specifically as follows:

[0024]

[0025] Among them, A represents the slurry consumption coefficient; R L represents the slurry diffusion radius; r represents the radius of the grouting hole layout circle; L represents the length of the grouting section; n represents the average fracture rate of the rock mass; B is the slurry filling coefficient; m is the slurry solidification rate;

[0026] Grout each branch hole according to the grouting volume of each branch hole, including: divide each branch hole into three grouting sections, namely the pre-fault grouting section, the mid-fault grouting section, and the post-fault grouting section; first grout the pre-fault grouting section, after the cement slurry solidifies, ream the hole, drill into the next section, then grout the mid-fault grouting section, after the cement slurry solidifies, ream the hole, and then drill into the next section, and finally grout the post-fault grouting section.

[0027] Preferably, the well logging includes: cuttings logging, drilling time logging, simple hydrographic observation, and natural gamma logging.

[0028] Preferably, evaluating the grouting effect includes:

[0029] Set the grouting qualification conditions, if the grouting qualification conditions are met, then the grouting is qualified; the grouting qualification conditions include:

[0030] The final grouting pressure needs to be greater than 2 times the net water pressure; the pump volume at the end of grouting is less than or equal to the pump volume threshold, and the stabilization time is greater than the time threshold; the actual slurry injection volume is not less than the grouting volume of each branch hole; the water pressure test pressure after grouting is greater than the water pressure test pressure before grouting.

[0031] Preferably, the hole sealing operation includes:

[0032] After all the grouting of the three-opening branch holes is completed, use single-fluid cement slurry and adopt the method of lowering a smooth drill pipe to seal the entire section of the first-opening vertical hole section and the second-opening deviated hole section. After the cement in the sealing section solidifies, the distance from the hole mouth of the borehole is less than or equal to the preset distance.

[0033] The embodiments of the present invention have at least the following beneficial effects: The present invention arranges a ground drilling site, designs a ground directional drilling structure and a drilling trajectory, and then drills holes in the ground drilling site according to the ground directional drilling structure and the drilling trajectory. Before the underground roadway is driven, the surrounding rock mass of the roadway is reinforced through the ground directional drilling, realizing the prior treatment of the fault. There is less mutual interference with underground operations, the construction period is saved, and the production efficiency is greatly improved. It can adapt to large faults with long strike extension, large drop, and large fault displacement. At the same time, the operation site is on the ground, the operation environment is good, and the safety is high. Through the grouting treatment of the surrounding rock, the operation environment of roadway driving, support, and maintenance is greatly improved, and the safety of driving, support, and maintenance work is improved; The grouting volume is calculated according to the designed reinforcement range, and grouting is carried out in the three-opening branch section according to the grouting volume. Compared with underground surrounding rock grouting, the grouting pump has a large flow rate, a long distance, a large reinforcement range, the slurry diffuses more fully, the filling rate of the fissures is higher, and the reinforcement quality is better. Moreover, sectional grouting can achieve targeted treatment of the fault position and avoid a large amount of waste of grouting materials; During the drilling process of the second-opening deflecting section and the third-opening branch section, logging is carried out to obtain logging data, further clarifying the geological conditions and fault structure characteristics around the roadway, which has strong guiding significance for subsequent driving and mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a method flow chart of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention;

[0036] Figure 2 It is a three-dimensional schematic diagram of the borehole layout of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention;

[0037] Figure 3 It is a longitudinal sectional schematic diagram of the borehole structure of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention;

[0038] Figure 4 It is a transverse sectional schematic diagram of the branch hole layout and reinforcement range of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention;

[0039] Figure 5The plan projection map of the actual drilling trajectory of the directional borehole for a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention;

[0040] Figure 6 The profile projection map of the directional borehole and the grouting section along the roadway for a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention.

[0041] The reference signs in the figure are shown as: 1 - ground drill site; 2 - first open vertical hole section; 3 - second open deviation section; 4 - third open branch section; 41 - roof hole; 42 - right rib hole; 43 - floor hole; 44 - left rib hole; 411 - pre-fault grouting section of the roof hole; 412 - in-fault grouting section of the roof hole; 413 - post-fault grouting section of the roof hole; 5 - roadway; 6 - fault; 7 - surface soil layer; 8 - target layer; 9 - first open casing; 10 - second open casing; 11 - landing point of the second open. Detailed implementation manners

[0042] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the drawings and preferred embodiments to detail the specific implementation manners, structures, features and their effects of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0044] The following specifically describes the specific solution of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by the present invention with reference to the drawings.

[0045] Embodiment:

[0046] The main application scenario of the present invention is: during the coal mining process, the roadway driving often encounters complex geological structures such as fault zones. The fault zone not only affects the stability of the roadway but also may cause safety problems such as roof caving and rib spalling, seriously affecting the production efficiency and safety of the mine. Therefore, it is particularly important to adopt the ground advanced exploration and treatment method to conduct advance exploration and treatment on the coal mine roadway passing through the fault zone. Through the application of the technical solution of the present invention, the advance exploration and treatment of complex geological structures such as fault zones can be realized, providing a strong guarantee for the safe production and efficient driving of the mine.

[0047] Please refer to Figure 1, which shows a method flow chart of a ground advanced exploration and treatment method for a coal mine roadway passing through a fault zone provided by an embodiment of the present invention. The method includes the following steps:

[0048] Step S1, arrange a ground drill site, and design the structure and trajectory of a ground directional borehole; the ground directional borehole structure includes a first-opening straight hole section, a second-opening inclined hole section, and a third-opening branch section; calculate and design the reinforcement range.

[0049] Before drilling, it is necessary to analyze the geographical data of the fault zone, and then proceed with the next step of construction to obtain the exploration data of the fault zone in the current mining area. The exploration data includes an exploration geological report and a 3D seismic report. Use the exploration data to obtain the basic characteristics of the fault zone, including the position trend, fault throw, drop, and dip angle of the fault zone. Furthermore, design the roadway passing through the fault. The geographical characteristics of the roadway include its position, trend, slope, and its relative position relationship with the fault. Determine the design reinforcement range according to the position, trend, slope of the roadway passing through the fault zone and its relative position relationship with the fault zone, arrange the position of the ground drill site, and design the structure and trajectory of the ground directional borehole, where the borehole structure includes a first-opening straight hole section, a second-opening inclined hole section, and a third-opening branch section.

[0050] The ground drill site should be set in a flat, open, and easily accessible location. When the roadway passing through the fault has an inclination, the ground drill site is preferably set on the side with a higher elevation of the roadway. Specifically, as Figure 5 、 Figure 6 shown, the roadway passes through the fault. According to the existing exploration data, it is inferred that the fault is located in the middle of the mining area, is a large normal fault, with a northeast trend, a southeast dip, a dip angle of 60 - 70°, a drop of 10 - 70m, and a strike length of about 2km in the mining area. The roadway drives along the strike of 284° and slopes along the coal seam towards the fault to cross the fault. The ground is mainly basic farmland, and a temporary land use is approved at a position about 400m northeast of the roadway to set up the ground drill site.

[0051] Set the ground directional borehole structure, as Figure 2As shown in the figure, the ground directional drilling structure is a three-opening structure, including a first-opening straight hole section, a second-opening deflecting hole section, and a third-opening branch hole section. The third-opening branch hole section includes four branch holes. The first-opening straight hole section, the second-opening deflecting hole section, and the third-opening branch hole section form a hole group. The first-opening straight hole section is connected to the second-opening deflecting hole section, and the second-opening deflecting hole section is connected to the third-opening branch hole section. The aperture of the first-opening straight hole section is the first preset value, the aperture of the second-opening deflecting hole section is the second preset value, and the aperture of the third-opening branch hole section is the third preset value. Preferably, the values of the first preset value, the second preset value, and the third preset value are 311 mm, 215.9 mm, and 152.4 mm respectively. One branch hole is provided on each of the roof, floor, left sidewall, and right sidewall of the roadway, namely: the roof hole is located directly above the roadway, the right sidewall hole is located on the right sidewall of the roadway, the floor hole is located directly below the roadway, and the left sidewall hole is located on the left sidewall of the roadway. Preferably, in the embodiment of the present invention, the roof hole is 3 m directly above the roadway, the right sidewall hole is 3 m on the right sidewall of the roadway, the floor hole is 3 m directly below the roadway, and the left sidewall hole is 3 m on the left sidewall of the roadway, as Figure 4 shown.

[0052] The design of the drilling trajectory includes: using professional software compass to design the drilling trajectory. The drilling trajectory parameters of the first-opening straight hole section, the second-opening deflecting hole section, and the roof hole are shown in Table 1:

[0053] Table 1. Example table of drilling trajectory parameters

[0054]

[0055]

[0056] Furthermore, it is also necessary to calculate the designed reinforcement range. The method for determining the designed reinforcement range is the plastic zone range of the surrounding rock after the roadway excavation. The calculation formula is:

[0057]

[0058] wherein, R is the radius of the plastic zone, that is, the designed reinforcement range; r 1 is the equivalent radius of the roadway; H is the depth of the roadway burial; γ is the average unit weight of the stratum; C is the cohesion of the surrounding rock; is the internal friction angle.

[0059] Substituting the relevant parameters of the mine, r 1 = 3 m, cohesion C = 20 MPa, γ = 2.5, H = 450 m, and internal friction angle φ = 35 into the formula, the radius of the designed reinforcement range is obtained as 12.16 m.

[0060] Step S2, at the ground drill site, drill holes according to the ground directional drilling structure and the drilling trajectory. The drilling operation of the first-opening straight hole section includes drilling, casing lowering, pipe solidification, and pressure testing; calculate the grouting volume according to the designed reinforcement range, and perform grouting in the third-opening branch hole section according to the grouting volume.

[0061] Furthermore, at the surface drilling site, drilling is carried out according to the surface directional borehole structure and borehole trajectory, including: 1. Drilling the first open vertical hole section, lowering the first open casing, cementing the first open casing, and pressure testing; 2. Drilling the second open deviated hole section, lowering the second open casing, cementing the second open casing, and pressure testing, while logging during drilling; 3. Drilling the third open branch section in segments, injecting slurry in a progressive three-stage manner, and logging during the drilling process.

[0062] According to the design scheme of the borehole, a suitable drill string assembly needs to be selected. The drill string assembly used in the first open vertical hole section is: Φ311mm roller bit + Φ172mm screw drill + 411*410 transition sub + Φ165mm non-magnetic drill collar + Φ165mm drill collar + Φ127mm drill pipe;

[0063] The drill string assembly used in the second open deviated hole section is: Φ215.9mm PDC bit + Φ172mm screw drill + Φ165mm directional sub + Φ165mm non-magnetic drill collar + Φ127mm drill pipe;

[0064] The drill string assembly used in the third open branch section is: Φ152.4mm PDC bit + Φ127mm screw drill + Φ121mm directional sub + Φ121mm non-magnetic drill collar + Φ89mm drill pipe + Φ89mm heavy drill pipe + Φ89mm drill pipe.

[0065] When drilling the third open branch section, the drilling depth of the third open branch section needs to be calculated. The calculation formula is:

[0066]

[0067] where M is the coal seam thickness or mining height (m), P is the water head pressure (MPa), K p is the tensile strength of coal (MPa), and K is the safety factor. The depth of the third open branch section should satisfy that the length after crossing the fault is not less than h. Preferably, in the embodiments of the present invention, the drilling depth of the third open branch section is set equal to h. The implementer can set the drilling depth of the third open branch section according to the actual situation of the mining area, but the depth must be greater than or equal to h.

[0068] When drilling the first open vertical hole section and the second open deviated hole section, operations such as lowering the casing and pressure testing need to be carried out as Figure 3 shown; among them, the aperture of the first open vertical hole section is 311mm, the specification of the first open casing is Φ244.5×8.94mm, the first open casing passes through the surface soil layer and enters the bedrock or stable formation for 5 - 10m, and the implementer can set it according to the specific situation; the aperture of the second open deviated hole section is 215.9mm, the specification of the second open casing is Φ177.8×8.05mm, and the second open casing reaches the target layer position; the third open branch section is an open hole with an aperture of 152.4mm.

[0069] The specific method for the casing is to circulate the drilling fluid to ensure the connectivity between the outer annulus of the casing and the inside of the casing, lower the casing to the designed position, inject single-fluid cement slurry into the casing for well cementing until the cement returns to the ground from the annular space outside the casing. The single-fluid cement slurry uses P·O42.5 cement, and the slurry density is not less than 1.6 g / cm 3 .

[0070] The pressure standard for pressure testing is 1.5 times the net water pressure and 1.2 times the designed grouting pressure. The qualified standard is that the pressure is maintained for 30 minutes and the pressure drop of the grouting does not exceed 0.5 Mpa. During the drilling operations of the first open vertical hole section, the second open deviated hole section, and the third open branch hole section, MWD measurement-while-drilling equipment is used for inclination measurement, and positive displacement motor is used for directional drilling.

[0071] Furthermore, grouting needs to be carried out in the third open branch hole section. Calculate the grouting volume according to the designed reinforcement range, and carry out grouting in the third open branch hole section according to the grouting volume. The grouting volume should ensure that the slurry diffusion range is not less than the designed reinforcement range. Construct geometric relationships based on the layout positions of the branch holes, such as Figure 4 shown in the figure. Make circles with 4 branch holes as the centers respectively. The intersections of the four circles and the designed reinforcement range divide the boundary of the designed reinforcement range equally. The slurry diffusion radius R L is 9.25 m. Further calculate the grouting volume. The calculation formula is:

[0072]

[0073] where A represents the slurry consumption coefficient, taking 1.2; R L represents the slurry diffusion radius; r represents the radius of the grouting hole layout circle, taking 6 m; L represents the grouting section length, which is 154.86 m; n represents the average rock fracture rate, taking 0.15; B is the slurry filling coefficient, taking 0.9; m is the slurry solidification rate, taking 0.85. The total designed grouting volume of the hole group is calculated to be 1796 m 3 , and at the same time calculate the grouting volume of each branch hole.

[0074] Meanwhile, the grouting volume of each branch hole is obtained, and then grouting is carried out. Each branch hole is grouted in three times, namely pre-fault grouting, in-fault grouting and post-fault grouting. That is, each branch hole is divided into three grouting sections, namely pre-fault grouting section, in-fault grouting section and post-fault grouting section for grouting. Among them, the pre-fault grouting range is from the landing point of the second opening to 20 - 30 m before the fault, the in-fault grouting range is from the end of the first-stage grouting to 10 m after the fault, and the post-fault grouting range is from 10 m after the fault to the bottom of the hole. The forward grouting method is adopted, that is, drill one section and grout one section. After the cement slurry solidifies, ream the hole and drill into the next section. Taking the roof hole 41 as an example, during grouting, first grout the pre-fault grouting section of the roof hole. After the cement slurry solidifies, ream the hole and drill into the next section. Then grout the in-fault grouting section of the roof hole. After the cement slurry solidifies, ream the hole and drill into the next section. Finally, grout the post-fault grouting section of the roof hole. The grouting end pressure of the pre-fault grouting section of the roof hole is 8.9 MPa, the grouting end pressure of the in-fault grouting section of the roof hole is 8.5 MPa, the grouting end pressure of the post-fault grouting section of the roof hole is 9.1 MPa, and the total grouting volume of the 41 branch hole is 476 m 3 . The drilling and grouting of the other three branch holes are the same as those of the roof hole.

[0075] Step S3, during the drilling process of the second-opening deviated section and the third-opening branch section, logging is carried out to obtain logging data, and the data is sorted out and summarized; evaluate the grouting effect and carry out hole sealing operation.

[0076] During the drilling operation, logging is required to obtain logging data, which is beneficial for subsequent analysis. Specifically, logging is carried out during the drilling process of the second-opening deviated section and the third-opening branch section. Logging includes cuttings logging, drilling time logging, simple hydrographic observation and natural gamma logging.

[0077] Specifically, cuttings logging includes: accurately fishing for cuttings at a unified position according to the logging interval and lag time, washing or rinsing according to different lithologies, drying and archiving, and recording the lithology; record 1 point every 10 m in the second-opening section, and gradually increase the density near the marked horizon. Record 1 point every 1 m in the third-opening branch section until the end of the hole;

[0078] Drilling time logging includes: record 1 point every 1 m on average from the bedrock section to the completion of the well. Record the sudden change points of the drilling time at any time to promptly discover coal seams, karst caves, fault fracture zones, and judge the starting and ending depths and lengths (thicknesses) of coal seams, karst caves, and fault fracture zones;

[0079] Simple hydrogeological observation includes: observing the water level once after each drill trip and before the next drill trip, and observing the water level in the hole once every hour during the drilling suspension; observing once every 2 hours during normal drilling, and observing once every 10 - 30 minutes when the increase in drilling fluid loss is found. When the drilling fluid loss > 5 m³ / h, stop drilling, measure the stable water level in the hole, and carry out grouting to stop the leak. When all the drilling fluid is lost, increase the pump volume to measure the maximum loss; when the hole encounters leaky, drill lost, severely collapsed strata in fault fracture zones, etc., record in detail the formation position, starting and ending depths of the hole; when water gushing is found during drilling, stop drilling immediately, determine the drilling depth and formation position, install a pressure gauge at the hole mouth to measure the borehole water pressure, and at the same time measure the water gushing volume and water temperature, and take water samples for water quality analysis;

[0080] Natural gamma logging includes: measuring the variation curve of formation radioactivity intensity with depth while drilling, and inferring lithology and fracture filling layers.

[0081] After obtaining the logging data, summarize and organize it to form a database for subsequent analysis and utilization.

[0082] During the grouting process of the branch hole, it is necessary to evaluate the grouting effect. Before and after grouting in each grouting section, a water pressure test is carried out to evaluate the grouting effect.

[0083] Taking the roof hole grouting as an example, the water pressure test pressures before and after grouting are:

[0084] Table 2. Water Pressure Test Record Sheet

[0085]

[0086] After obtaining the water pressure test effect, comprehensively evaluate the grouting effect by combining the grouting volume, final grouting pressure, and pump volume at the end of grouting. Specifically, set the qualified conditions for grouting. If the qualified conditions for grouting are met, the grouting is qualified. The qualified conditions for grouting are respectively:

[0087] 1. The final grouting pressure > 2 times the hydrostatic pressure;

[0088] 2. The pump volume at the end of grouting ≤ pump volume threshold, and the stable time > time threshold;

[0089] 3. The actual slurry injection volume is not less than the theoretical grouting volume, and the theoretical grouting volume refers to the calculated grouting volume for each branch hole;

[0090] 4. The water pressure test pressure after grouting is greater than the water pressure test pressure before grouting.

[0091] Among them, preferably, the pump volume threshold is 60 L / min, the time threshold is 30 min, and the greater the actual slurry injection volume and the water pressure test pressure after grouting, the better the grouting effect.

[0092] Finally, hole sealing operation and site restoration are required. Site restoration includes the demolition of temporary buildings, the breaking of hardened sites, the disposal of construction waste, and the restoration of land. After the grouting of all three-opening branch holes in the hole group is completed, a single-fluid cement slurry with a water-cement ratio ≤ 0.8 and a specific gravity ≥ 1.6 is used to seal the entire first-opening straight hole section 2 and the second-opening deflecting hole section 3 by lowering a smooth drill pipe. After the cement in the sealed section solidifies, the distance from the drill hole orifice is less than or equal to the preset distance. Preferably, the preset distance is 5m.

[0093] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. And the above description of specific embodiments of this specification has been made. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0094] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized.

[0095] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for ground advance exploration and control of coal mine tunnels passing through fault zones, characterized in that: The method includes: Arrange the ground drilling site and design the ground directional drilling structure and drilling trajectory; the ground directional drilling structure includes a straight hole section, a deflection section, and a branch section; calculate and design the reinforcement range; The first opening straight hole section is connected with the second opening inclined section, and the second opening inclined section is connected with the third opening branch section; the third opening branch section has 4 branch holes, namely the top plate hole, the right side hole, the bottom plate hole and the left side hole; the top plate hole is located directly above the tunnel, the right side hole is located on the right side of the tunnel, the bottom plate hole is located directly below the tunnel, and the left side hole is located on the left side of the tunnel; At the ground drilling site, drilling is carried out according to the ground directional drilling structure and drilling trajectory. The drilling operation of the first straight hole section includes drilling, casing lowering, pipe fixing and pressure testing. The grouting amount is calculated according to the designed reinforcement range, and grouting is carried out in the third branch section according to the grouting amount. The designed reinforcement range is the plastic circle radius. Circles are drawn with the four branch holes as the center, and the intersection of the four circles and the designed reinforcement range divides the boundary of the designed reinforcement range into equal parts. The grouting diffusion radius can be obtained by combining the designed reinforcement range with the geometric relationship. During the drilling process of the second opening and the third opening branch section, logging is carried out to obtain logging data and organize and summarize them; the grouting effect is evaluated and sealing operations are carried out.

2. A method for ground advance exploration and control of coal mine tunnels passing through fault zones according to claim 1, characterized in that: The method of arranging the ground drilling site includes: when a tunnel passing through a fault has an inclination angle, the ground drilling site is arranged on a side with a higher elevation of the tunnel.

3. A method for ground advance exploration and treatment of coal mine tunnels passing through fault zones according to claim 1, characterized in that: The designing of the drilling trajectory includes: using the professional software Compass to design the drilling trajectory.

4. The method for ground advance detection and treatment of coal mine tunnels passing through fault zones according to claim 1 is characterized in that: The calculation formula for the design reinforcement range is: Among them, R is the radius of the plastic zone, i.e. the designed reinforcement range; r1 is the equivalent radius of the tunnel; H is the tunnel burial depth; γ is the average bulk density of the stratum; C is the cohesion of the surrounding rock; is the internal friction angle.

5. The method for ground advance exploration and treatment of coal mine tunnels passing through fault zones according to claim 1 is characterized in that: The drilling according to the ground directional drilling structure and drilling trajectory includes: The first section is drilled, the first section is lowered, the first section is fixed, and the pressure is tested; the second section is drilled, the second section is lowered, the second section is fixed, and the pressure is tested, and logging is carried out during drilling; the third section is drilled in sections, and the forward stage grouting is carried out; First, the casing is opened through the surface soil layer into the bedrock or stable formation, and second, the casing is opened to the target layer; the casing cementing includes: circulating drilling fluid to ensure the connectivity between the outer annular cavity of the casing and the inside of the casing, lowering the casing to the designed position, and injecting a single-liquid cement slurry into the casing for cementing until the cement returns to the ground from the annular space outside the casing, thereby completing the casing cementing; When drilling three-way branch segments, it is necessary to calculate the drilling depth of each branch segment of the three-way opening. The calculation formula is: Where h is the drilling depth of each branch section, M is the coal seam thickness or mining height, P is the water head pressure, K p is the tensile strength of coal, and K is the safety factor.

6. The method for ground advance exploration and treatment of coal mine tunnels passing through fault zones according to claim 1 is characterized in that: The grouting amount is calculated according to the designed reinforcement range, and grouting is performed in the three-opening branch section according to the grouting amount, including: The geometric relationship is established according to the arrangement position of the branch holes, and the slurry diffusion radius is obtained in combination with the designed reinforcement range; the grouting volume of each branch hole is calculated, specifically: Where A represents the slurry consumption coefficient; R L represents the slurry diffusion radius; r represents the radius of the grouting hole arrangement circle; L represents the grouting section length; n represents the average fracture rate of the rock mass; B is the slurry filling coefficient; and m is the slurry solidification rate.

7. The method for ground advance detection and treatment of coal mine tunnels passing through fault zones according to claim 1 is characterized in that: The logging includes: cuttings logging, drilling logging, simple hydrological observation and natural gamma logging.

8. The method for ground advance exploration and treatment of coal mine tunnels passing through fault zones according to claim 1 is characterized in that: The evaluation of the grouting effect comprises: Set the grouting qualification conditions. If the grouting qualification conditions are met, the grouting is qualified. The grouting qualification conditions include: The final grouting pressure must be greater than twice the clean water pressure; the pump volume at the end of grouting is less than or equal to the pump volume threshold, and the stabilization time is greater than the time threshold; the actual slurry injection volume is not less than the grouting volume of each branch hole; the water pressure test pressure after grouting is greater than the water pressure test pressure before grouting.

9. The method for ground advance exploration and treatment of coal mine tunnels passing through fault zones according to claim 1, characterized in that: The sealing operation comprises: After grouting of all three branch holes is completed, use single-liquid cement slurry and the lower-light drill rod method to fully seal the first straight hole section and the second inclined hole section. After the cement in the closed section solidifies, the distance between it and the borehole mouth is less than or equal to the preset distance.

Images