Tunnel underlying steeply inclined coal mine goaf treatment method

Abstract

The invention belongs to the technical field of goaf treatment, and particularly relates to a tunnel underlying steeply inclined coal mine goaf treatment method which comprises the following steps: (1) zoning a goaf treatment range: dividing the goaf treatment range into an upper half region and a lower half region, dividing the upper half region into a region I, a region II and a region VI, and dividing the lower half region into a region III, a region IV and a region V; (2) drilling holes are distributed, specifically, curtain holes are distributed in the area I, the area III and the area IV, the distance between the curtain holes is 10 m, grouting holes are distributed in the area II, the area V and the area VI, the grouting holes are distributed in a quincunx shape, the distance between the grouting holes is 20 m, the drilling inclination angle of the curtain holes and the grouting holes ranges from 48 degrees to 62 degrees, and the drilling length ranges from 25 m to 180 m; (3) drilling construction; (4) grouting is conducted, specifically, specific grout is adopted for grouting and filling in the subareas; and (5) hole sealing. A new scheme is provided for treatment of the inclined long-distance drilling grouting goaf above 100 m, and safe operation of railways and harmony and stability of the society are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of gob area treatment, and particularly relates to a method for treating gob areas of steeply inclined coal mines under tunnels. Background Art

[0002] China has been mining coal for many years, and a large number of gob areas with different depths, different areas and even multiple layers have been accumulated or are being formed. With the rapid development of railway engineering construction, many railway projects cannot avoid passing through coal mine gob areas. Therefore, gob area treatment has become a major problem that must be solved in railway operation. At present, the treatment of gob areas under railways mainly relies on experience, and methods such as caving method, filling method, support method, and closed isolation method are respectively used according to the geological conditions of the gob areas. Among them, the grouting filling method is the most commonly used treatment method. The design of gob area treatment plans is affected by the mining conditions, geological conditions, and dynamic loads of the gob areas. At present, there is no precedent in China for grouting treatment of gob areas with inclined long-distance boreholes over 100m for reference. Therefore, when encountering gob areas that require 100m inclined long-distance boreholes, due to the lack of construction experience, the actual construction difficulty is high; moreover, when the gob area is large, it is very difficult to set up a grout stop wall within the entire gob area and then grout and fill, which seriously affects the construction period. Summary of the Invention

[0003] The present invention aims to provide a method for treating gob areas of steeply inclined coal mines under tunnels, in order to provide a new solution for grouting treatment of gob areas with inclined long-distance boreholes.

[0004] To achieve the above object, the solution of the present invention is: a method for treating gob areas of steeply inclined coal mines under tunnels, comprising the following steps:

[0005] (1) Partitioning the gob area treatment scope: dividing the gob area treatment scope into an upper half area and a lower half area. The lower half area is for underwater grouting. Divide the upper half area into Area I, Area II and Area VI, and divide the lower half area into Area III, Area IV and Area V;

[0006] (2) Borehole layout: Install curtain holes in Area I, Area III and Area IV, with a curtain hole spacing of 10m. Install grouting holes in Area II, Area V and Area VI. The grouting holes are arranged in a plum blossom shape with a spacing of 20m. The drilling inclination angles of the curtain holes and the grouting holes are 48° - 62°, and the drilling lengths are 25 - 180m;

[0007] (3) Borehole construction:

[0008] a) Use a total station to position and mark lines on the ground or arch of the drill site, lay out the opening points, measure the position of the drill rig, determine the azimuth angle, use a trajectory instrument for inclination angle positioning, and use an opening orientation instrument for azimuth angle positioning and inclination angle verification;

[0009] b) Use a rotary drill to drill holes. The deviation of the drilled hole from the designed hole position shall not be greater than 0.5 m, and the deviation of special hole positions shall not be greater than 0.1 m. The hole inclination shall be measured every 50 m of drilling, and the hole deviation per 100 m shall not exceed 1°;

[0010] c) When the grouting holes and curtain holes drill into the fracture zone and caving zone, use clear water for drilling. In case of phenomena such as water leakage and drill dropping during drilling, records shall be made; when caving or drill burying occurs during drilling, analyze the reasons in time, find out the situation, and adopt the method of drilling with casing or grouting first and then drilling;

[0011] d) After the drilling is completed, hole flushing shall be carried out. The sediment at the bottom of the hole shall not block the effective grouting area. When the drilling operation is temporarily suspended and before grouting of the final hole, the hole opening shall be covered for protection;

[0012] (4) Grouting: First, grout and fill area Ⅰ to form a curtain grout stop wall. After the curtain grout stop wall in area Ⅰ is formed, grout and fill area Ⅱ from low to high and from both sides to the middle. Then grout and fill area Ⅵ, and then grout and fill area III to form a curtain grout stop wall. After the curtain grout stop wall in area III is formed, grout and fill area IV to form a partition wall. After the partition wall is formed, grout and fill area V;

[0013] Among them, cement-sodium silicate double-fluid grout is used for grouting in area Ⅰ. The water-cement ratio of the cement-sodium silicate double-fluid grout is 0.6, and the volume ratio of cement slurry to sodium silicate slurry is 3:1; cement-fly ash slurry is used for grouting in area Ⅱ. The water-binder ratio of the cement-fly ash slurry is 0.6, and the volume content of fly ash is 20% of the volume of the cement-fly ash slurry; quick-setting controllable underwater anti-dispersant slurry is used for grouting in areas III and IV. The water-binder ratio of the quick-setting controllable underwater anti-dispersant slurry is 0.6, and the volume content of the quick-setting anti-dispersant is 25% of the volume of the quick-setting controllable underwater anti-dispersant slurry; underwater anti-dispersant slurry is used for grouting in area V. The underwater anti-dispersant slurry is cement-fly ash slurry plus underwater anti-dispersant. The water-binder ratio of the underwater anti-dispersant slurry is 0.6, the volume content of fly ash is 20% of the volume of the underwater anti-dispersant slurry, and the volume content of the underwater anti-dispersant is 1% of the volume of the underwater anti-dispersant slurry; pure cement slurry is used for grouting in area Ⅵ. The water-binder ratio of the pure cement slurry is 0.6;

[0014] When the unit grouting volume is less than 70 L / min under the designed pressure and remains stable for more than 15 min during grouting, the grouting shall be terminated;

[0015] The stone formation rate of the slurry in each area shall not be less than 85%, and the stone strength of the slurry shall not be lower than 2 MPa;

[0016] (5) Hole sealing: After the grouting of the whole hole is completed, pull out the grout stop facilities, pour thick cement slurry into the hole from the hole opening, and the hole sealing is completed after the slurry reaches the hole opening.

[0017] Optionally, in step (3), before step a), first detect the coal seam strike through horizontal drilling, and calculate the horizontal distance, azimuth, theoretical dip angle of the final hole coordinates, and theoretical drilling length from the drilling hole to the coal seam;

[0018] It can be known from the drawing that the dip angle of the coal seam is θ. Locate the horizontal distance from the coal seam to the drill site by drilling a horizontal hole in the drill site, and record this distance as X1. Calculate the height difference by the elevation of the final hole of the formed hole and the elevation of the drill site, and record this height difference as h. Through the trigonometric function relationship, construct formula (1-1) to calculate the distance X2 from the final hole of the formed hole on the projection zone of the drill site to the coal seam; According to the design description, know the distance between the empty spaces, and record this distance as d. Calculate the projected length l of the formed hole on the plane of the final hole of the formed hole through formula (1-2), and calculate the dip angle θ through formula (1-3) 倾 , calculate the horizontal angle θ through formula (1-4) 水 ; Through the above geometric calculations, it can be reconciled with the coordinate calculations, and the reliability of the data can be verified through the reconciliation calculations; Use houdini modeling software to simulate the spatial layout of the drilling holes, and timely optimize and adjust the drilling hole positions;

[0019]

[0020] Optionally, in step (3), when the hole deviation exceeds 1° per 100 meters, hole deviation correction is required:

[0021] a) Grouting plugging and re-opening for hole deviation correction: Use cement plus triethanolamine composite admixture as the plugging material, and the water-cement ratio is 0.75:1 to 0.6:1; Maintain the pressure of the plugging hole deviation for 20 minutes after reaching the final pressure. When the final pressure cannot be reached, long-term maintenance is required; After maintenance, use light pressure and slow rotation to correct the hole deviation. When the deviation and azimuth of the newly drilled hole meet the requirements, it can be transferred to normal drilling;

[0022] b) Reaming: Use a reaming bit with more wing blades to slowly ream the hole from above the deviation area, and prevent slipping when encountering a step;

[0023] c) Boring: Replace the drill bit with a larger one than the original to enlarge the hole diameter, correct the drilling hole, ream to the original depth, then replace it with the original drill bit, suspend the drill string about 1m, slowly lower it to drill a new hole, measure the hole deviation to be qualified after drilling 1-2m, and then transfer to normal drilling;

[0024] d) Shoveling: From the upper part of the deviation area, use a heavy pipe with a shoveling bit to remove the deviated part with a vertical impact force. Each stroke is about 2m. Rotate the drill string while shoveling. After shoveling one or two circles, perform the second stroke. After shoveling out a step, use a reaming bit to enlarge the shoveled section. Alternate shoveling and reaming until it cannot be shoveled anymore, and then ream the hole to the bottom; When shoveling the hole, pay attention to aligning the three points in a straight line to prevent central deviation and affect the hole shoveling.

[0025] Optionally, in step (4), when slurry leakage occurs locally in area III, a 50-fold boundary expansion grouting pad is used for plugging.

[0026] Optionally, in step (4), the bottom of areas III and IV is grouted with a quick-setting and controllable underwater anti-dispersant slurry, and above the bottom of areas III and IV, a cement-sodium silicate-anti-dispersant double-fluid slurry is used for grouting. The water-binder ratio of the cement-sodium silicate-anti-dispersant double-fluid slurry is 0.6, the volume admixture of sodium silicate is 25% of the volume of the cement-sodium silicate-anti-dispersant double-fluid slurry, and the volume admixture of the anti-dispersant is 1% of the volume of the cement-sodium silicate-anti-dispersant double-fluid slurry.

[0027] Optionally, in step (4), the grouting pressure ≥ 1 MPa.

[0028] Optionally, in step (4), the distance between adjacent partition walls is 50 m.

[0029] Optionally, the following steps are further included:

[0030] (6) Grouting quality inspection: The grouting effect inspection is carried out 1 month after the grouting construction is completed, and four methods are used for comprehensive analysis and judgment: First, the grouting effect is detected by drilling holes in the repaired roadway, and the grouting filling rate is not less than 90%; second, cores are taken from 10% of the grouting holes to measure the rock strength, and the uniaxial compressive strength of the stone is not less than 2 MPa; third, inspection holes are drilled to measure the ultrasonic wave propagation speed in the grouted and reinforced goaf; fourth, statistical analysis of the grouting volume of partitioned holes.

[0031] Optionally, the specific operation for drilling inspection holes to measure the ultrasonic wave propagation speed in the grouted and reinforced goaf is as follows: Comprehensive measurement is carried out before and after grouting using an ultrasonic wave or a high-power acoustic wave instrument. It is required that the average shear wave (transverse wave) speed in the grouted section of the drill hole > 350 m / s; when conducting statistical analysis of the grouting volume of partitioned holes, the ending condition for each group is that the slurry volume injected into the hole per unit time is less than 50 L / min, the grouting duration is 15 - 20 min, and the final hole pressure is 2 - 3 MPa.

[0032] The working principle and beneficial effects of this solution are as follows: In this solution, the drilling inclination angle is 48° - 62°, and the drilling length is 25 - 180 m. Grouting is carried out by the method of grouting in zones within the treatment range of the goaf from the floor rock roadway. Mainly, the treatment range of the goaf is divided into the upper half area and the lower half area. In areas I, II, and VI of the upper half area, area I is curtain grouting, using cement-sodium silicate double liquid slurry. To ensure the effect of the grout stop wall, the gel time of the slurry is controlled within 2 - 5 minutes. Area II uses cement-fly ash slurry for filling grouting, and area VI uses neat cement slurry to strengthen the filling of the tunnel bottom; in the three areas III, IV, and V of the lower half area, underwater grouting is carried out. Areas III and IV are curtain grouting, using quick-setting controllable underwater anti-dispersant slurry (at the bottom) and cement-sodium silicate-anti-dispersant double liquid slurry (above the bottom). The gel time of the slurry is controlled within 2 - 5 minutes; due to the complex environment in the goaf, there may be loopholes in area III where the curtain cannot be continuous, and a 50-fold boundary expansion grout stop pad is locally used; area V uses underwater anti-dispersant slurry for grouting, and the diffusion radius of the slurry is controlled to be not less than 15 m. The stone formation rate of the slurry in each area is not less than 85%, and the strength of the stone body is not lower than 2 MPa. To improve the quality of the grouting liquid and the grouting effect, high-speed stirring is introduced in the mixing process link. According to the on-site experiment configuration, ensure the strength, stone formation rate, diffusion radius, etc. In case of the phenomenon of long-term groundwater flow, increase the dosage of water glass and anti-dispersant as appropriate.

[0033] To sum up, this solution realizes oblique long-distance drilling grouting of more than 100 m, effectively solves the problem of underwater grouting below the elevation of +400 m, reduces the influence of the goaf in the deep stratum on the strength of the shallow foundation soil, reduces the uneven settlement amount, improves the overall performance of the foundation rock and soil mass, ensures the safe operation of the railway and social harmony and stability, and provides a reference for the treatment of steeply inclined goaf under similar tunnels. Brief Description of the Drawings

[0034] Figure 1 It is the plane schematic diagram of goaf grouting in Embodiment 1 of the present invention;

[0035] Figure 2 It is the sectional view of the drilling layout of goaf grouting in Embodiment 1 of the present invention;

[0036] Figure 3 It is the simulated drilling space layout diagram using houdini modeling software in Embodiment 1 of the present invention;

[0037] Figure 4 It is the schematic diagram of downward grouting in the upper half area and the lower half area in Embodiment 1 of the present invention. Detailed Description of the Specific Embodiment

[0038] The following is a further detailed description through specific embodiments:

[0039] Example 1

[0040] This example is described in detail with the governance project of the mined - out area of Zhengyang Town Tunnel in Chongqing. Project introduction: Zhengyang Town Tunnel of the Chongqing - Qianjiang Railway is located in Chengnan Sub - district and Zhengyang Sub - district of Qianjiang District, Chongqing. The starting and ending mileage is DK256 + 445~DK260 + 064, with a total length of 3619m and a maximum buried depth of 334.8m. The section from DK257 + 939.699 to DK258 + 620.627 of the tunnel body is a left - hand curve with R = 3500m, and the section from DK258 + 780.723 to DK259 + 912.962 is a right - hand curve with R = 2200m, and the rest are straight lines. The designed longitudinal slopes are: single - sided downhill slopes of - 13.5‰, - 3‰, 0‰ and a flat slope. The elevation of the tunnel body line is 567.184~527.17m. The tunnel is a double - track tunnel for a passenger dedicated line electrified railway with a designed speed of 350Km / h, a ballasted track, and the speed limit for tunnel operation is 200km / h. Zhengyang Town Tunnel passes through the mined - out area of the former Longqiao Coal Mine at the section of DK258 + 301~+638. In order to ensure the safety of the later railway operation, the governance of the influence range of the coal mining in the mined - out area passed through by Zhengyang Town Tunnel is carried out. The groundwater level in the mined - out area is lowered to the elevation of + 400m, and the water level is maintained below the elevation of + 400m.

[0041] This example provides a method for governing the mined - out area of a steeply inclined coal mine underlying a tunnel, including the following steps:

[0042] (1) Zoning of the governance scope of the mined - out area: The governance scope of the mined - out area is divided into the upper half area (above the elevation of + 400m) and the lower half area (below the elevation of + 400m). The lower half area is for underwater grouting. The upper half area is divided into Area I, Area II and Area VI, and the lower half area is divided into Area III, Area IV and Area V, as Figure 1 shown.

[0043] (2) Borehole layout: Before construction, a ground control survey network is established. The ground control network should be connected with the original coal mine control network. It is measured from the north - side portal at + 485 to the portal at + 714, and the traverse is reviewed. Inside the tunnel, measurement control points are arranged at the key parts of the + 485 and + 400 roadways for borehole positioning measurement. After actual measurement, the actual plane position and elevation of the drill site are collected, and the actual drill - site layout map of the mined - out area is drawn. According to the actual drill - site position and the following requirements, boreholes are arranged: Curtain holes are arranged in Area I, Area III and Area IV, with a spacing of 10m between curtain holes. Grouting holes are arranged in Area II, Area V and Area VI, and the grouting holes are arranged in a plum - blossom shape with a spacing of 20m. The drilling inclination angles of the curtain holes and the grouting holes are 48°~62°, and the drilling lengths are 25~180m. The borehole profile / plan layout is as Figure 2 shown.

[0044] (3) Borehole construction:

[0045] a) Drilling equipment selection: Select the ZDY-6500 type drill rig (overall dimensions 4350×1050×1830mm), final hole diameter 94mm, maximum drilling depth of the equipment 400m; The ZDY6500LP(S) drill rig type is a fully hydraulic, high-power, crawler-type, stepless speed regulation crawler-type tunnel drill rig. The installed power of the equipment is currently set at 75kW, rated torque 1400 - 6500 N·m, the rock-breaking efficiency is increased by 30%, and the through-hole diameter of the drill rig power head can reach to meet the use of various specifications of drill tools; The multi-degree-of-freedom amplitude-changing mechanism is convenient for angle adjustment and stabilization, and the drill rig has a large angle adjustment range; Angle adjustment device: Supported by a hydraulic cylinder, the angle adjustment process of the drill rig is hydraulically controlled, azimuth angle adjustment -90° to +90°, horizontal lifting 0.65m, and the opening height can be adjusted within the range of 1.25 - 1.9m; The excavation dimensions of the drill site are 5m in length × 4m in height × 4.2m in depth, meeting the drill rig positioning conditions.

[0046] b) Drilling positioning: First, detect the coal seam strike through a horizontal drill hole, calculate the horizontal distance, azimuth angle, theoretical dip angle of the final hole coordinate, and theoretical drilling length from the drill hole to the coal seam;

[0047] It can be known from the drawing that the inclination angle of the coal seam is θ. Drill a horizontal hole in the drill site to position the horizontal distance from the coal seam to the drill site, and this distance is denoted as X1. Calculate the height difference by the elevation of the final hole of the formed hole and the elevation of the drill site, and this height difference is denoted as h. Through the trigonometric function relationship, construct formula (1-1) to calculate the distance X2 from the final hole of the formed hole on the projection belt of the drill site to the coal seam; According to the design description, know the distance between the empty spaces, and this distance is denoted as d. Calculate the projected length l of the formed hole on the plane of the final hole of the formed hole through formula (1-2), and calculate the inclination angle θ through formula (1-3) 倾 , calculate the horizontal angle θ through formula (1-4) 水 ; Through the above geometric calculations, it can be checked with the coordinate calculations to verify the reliability of the data through the verification calculations; Use houdini modeling software to simulate the spatial layout of the drill holes (as Figure 3 shown), and timely optimize and adjust the drill hole positions;

[0048]

[0049]

[0050] c) Drilling preparation: Use a total station to position and mark on the ground or arch of the drill site, lay out the opening points, measure the drill rig positioning, determine the azimuth angle, use a trajectory instrument for dip angle positioning, and use an opening orientation instrument for azimuth angle positioning and dip angle verification.

[0051] d) Drilling: Use a rotary drilling rig for drilling. The deviation between the drilled hole and the designed hole position should not be greater than 0.5m, and the deviation of special hole positions should not be greater than 0.1m. The drilling inclination should be measured every 50m, and the hole inclination should not exceed 1° per 100 meters. Use drill collars and stabilizers to assist in drilling to prevent the hole from deviating too much, apply drilling pressure to the drill bit to ensure the necessary strength under compression conditions, reduce the vibration, swing, and jump of the drill bit, make the drill bit work smoothly, and control the deviation error.

[0052] e) When drilling grouting holes and curtain holes to fracture zones and falling zones, use clean water for drilling. If water leakage or drill bit falling occurs during drilling, records should be kept. If the hole collapses or drill bit is buried during drilling, analyze the cause in time, find out the situation, and use follow-up drilling or grouting before drilling.

[0053] f) After drilling is completed, the borehole should be flushed and the sediment at the bottom of the hole should not block the effective grouting area. When the drilling operation is temporarily suspended and before the final hole is grouted, the hole mouth should be covered for protection.

[0054] (4) Hole skew correction:

[0055] a) Grouting and plugging to reopen the hole and sweep the inclination: cement plus triethanolamine composite admixture is used as the plugging material, and the water-cement ratio is 0.75:1~0.6:1; the plugging hole inclination pressure reaches the final pressure and is maintained for 20 minutes. When the final pressure cannot be reached, long-term maintenance is required; after maintenance, use light pressure and slow rotation to sweep the inclination. Normal drilling can only be resumed when the inclination and azimuth of the new hole meet the requirements.

[0056] b) Sweeping: Use a drilling bit with more wings to slowly sweep the hole from the top of the deviated part downwards. Prevent it from slipping when encountering steps.

[0057] c) Expansion: Use a drill bit larger than the original drill bit to enlarge the hole diameter, correct the borehole, expand to the original depth and then replace the original drill bit. Suspend the drill tool about 1m, slowly lower it to drill a new hole, drill 1-2m and pass the inclination measurement, then switch to normal drilling.

[0058] d) Shoveling: From the upper part of the deviated part, use a weighted tube with a shoveling drill bit to scrape off the deviated part with the force of vertical impact. Each stroke is about 2m. Rotate the drill bit while shoveling. After shoveling one or two circles, make the second stroke. After shoveling out the step, use the reaming drill bit to expand the shoveled section. Alternate shoveling and expanding until it can no longer be shoveled, and then expand the hole to the bottom. When shoveling the hole, pay attention to aligning the three points in a straight line to prevent the center from deviating and affecting the shoveling hole.

[0059] e) Relocate the hole: When other methods of dealing with the deflection are ineffective, relocate the hole and drill another hole if the design allows.

[0060] f) Correction: Use the stabilizer to correct the deviation in a directional manner.

[0061] (5) Grouting:

[0062] a) Grouting system configuration: The grouting system consists of a material yard, a primary mixing tank, a secondary mixing tank, a water supply system, a batching sub-station, a grouting pump, a pressure gauge, a hole-sealing device, and grouting pipelines. Among them, the grouting pump: adopts HBC90 (95m 3 / h) + BW-1000 / 12 type (60m 3 / h); the pressure gauge: the grouting hole pressure gauge is 10MPa and 4MPa. The cement-fly ash slurry must be stirred in two stages. There should be a height difference between the primary and secondary mixers to facilitate slurry discharge and debris filtration. The slurry discharge door should be easy to open and close, not easily blocked, and it is not advisable to use a gate valve; there should be enough spare parts for the vulnerable parts of the grouting pump such as steel balls, valve seats, cylinder liners, pistons, and tie rods; the grouting pipelines in the grouting station should have as few elbows as possible, and the equipment and pipelines should be arranged compactly for easy operation and management; the pipeline from the ground to the underground is connected by a φ108mm steel pipe flange and transported to the underground drilling site.

[0063] b) Slurry transportation channel configuration: The grouting hole pipe is selected as a φ108mm steel pipe, and a ball valve and an exhaust valve are installed at each hole; the method of using a grout stopper, casing, and Marisan capsule bag is used for grout stopping; the hole-sealing device: grouting is carried out with a 50mm diameter steel pipe, connected by screw threads, and a circular flange tray (the tray diameter is between 120 and 130mm) is welded at 20 - 30cm from the front end of the pipe and lowered into the variable diameter part of the hole; the grouting pipe: uses a 50mm diameter steel pipe; the grouting pressure ≥1MPa.

[0064] c) Equipment configuration in the grouting site: In the tunnel, 3S500 type grouting pumps are respectively used to grout the filling holes, with four sets configured, and the single - pump grouting capacity is 30m 3 / h; two double - liquid grouting pumps, 3S300 - 20 type, are configured for the curtain grout - stopping wall, and the grouting capacity is 18m 3 / h; one mixing barrel is configured for each grouting area, with a diameter of 1.2 meters and a height of 1.5 meters, to perform secondary mixing on the slurry transported to the grouting area, and one slurry storage barrel, with a diameter of 2.0 meters and a height of 1.5 meters; the motor is selected as WJG - 700 type, with a power of 7.5KW.

[0065] d) Debugging the grouting pump and supporting facilities

[0066] Arrange 2 double - liquid grouting machines, install 2 three - stage grouting mixing tanks, 1 cement tank, and 1 water glass dilution tank in the drilling site. Install coal - mine special flow meters on the grouting pipelines of the two pieces of equipment respectively, and install a pressure gauge on the hole - mouth grouting pipe, and install a pressure gauge on the grouting equipment. Before starting the pump, first adjust the three - way rotary core valve to the return - slurry position. When the pump absorbs water normally, slowly reduce the three - way return - slurry port, and the pump pressure will rise gradually. When the pump pressure reaches the predetermined grouting pressure and there is no failure for two or three minutes, it can be ended.

[0067] e) Commission the grouting system and conduct a pressure test on the grouting pipeline

[0068] After the equipment is installed in place, conduct commissioning and a pipeline pressure test. The slurry is stirred according to the mix ratio selected for the test. The mixing time at the batching plant is not less than 3 minutes. It is transported through the pipeline to the storage bin at the drilling site. When the slurry enters the secondary mixing tank, it must be filtered through a sieve and stirred for more than 3 minutes again. The residence time should not exceed 4 hours.

[0069] f) Borehole flushing and water pressure test

[0070] Before grouting, conduct a void and fracture flushing for the whole hole once. The flushing pressure is 80% of the grouting pressure and not greater than 1 MPa. The flushing time is 5 - 10 minutes. When the water leakage volume is greater than 100 L / min, stop flushing. For rock formations that are easily softened by water, void and fracture water pressure flushing may not be carried out before grouting. During the construction process, for boreholes where there is no water return in the hole and no drill bit dropping, water pressure flushing may not be carried out. After the borehole is completed, conduct hole cleaning inspection. Only when it is confirmed that there is no cave-in and protruding rock, can the pipe be lowered. Otherwise, it is necessary to use the drill rig to ream the hole.

[0071] g) Install the grout stopper: After determining that there is no blockage in the grouting pipe, the grouting pipe can be installed. The hole sealing device uses a steel pipe with a diameter of 50 mm for grouting. A circular flange tray (the diameter of the tray is between 120 - 130 mm) is welded at 20 - 30 cm from the front end of the pipe and lowered to the variable diameter section in the hole.

[0072] h) Slurry preparation: Select two sets of MZG - 50 type integrated slurry preparation equipment for centralized slurry preparation. The slurry preparation capacity of each set of grouting equipment is 50 m 3 / h; The slurry preparation is divided into two - stage stirring. The stirring time in the first - stage mixing tank should not be less than 3 minutes, and then it is put into the second - stage mixing tank. When the slurry enters the second - stage mixing tank, it must be filtered through a sieve. The residence time should not exceed 4 hours.

[0073] i) Grouting process: The schematic diagram of downward grouting in the upper and lower regions is as Figure 4 shown. The grouting pressure ≥ 1 MPa, which is considered comprehensively according to the geological conditions of the grouted formation, the slurry absorption volume during grouting, and the transformation of slurry consistency, etc. Generally, when the slurry absorption volume is small, the specified grouting pressure can be reached as soon as possible; while when the slurry absorption volume is large, it can be slowly increased to the specified grouting pressure.

[0074] During the grouting process, the "one-time pressure increase method" is adopted to control the grouting pressure. That is, after the grouting starts, the pressure is quickly increased to the specified pressure, so that the entire grouting process is carried out under the specified pressure as much as possible. The grouting adopts the method of first using a thinner slurry concentration and then a thicker one. After the grouting starts, the slurry suction volume and pump pressure of the pump should be observed regularly, various phenomena occurring during the grouting process should be recorded, original data should be collected, and the grouting volume and slurry concentration should be adjusted in a timely manner according to the actual situation. When the grouting pressure remains unchanged and the unit slurry suction volume continuously decreases, or when the unit slurry suction volume remains unchanged and the pressure continuously increases, the water-solid ratio should not be changed. When the injection volume of a certain concentration of slurry has reached more than 20% of the designed volume or the injection time has reached 2 hours, and there is no obvious change in the grouting pressure and unit slurry suction volume, the grouting should be adjusted to a higher concentration level by one or two levels. When the unit slurry suction volume is greater than 250 L / min, the concentration can be changed to a higher level by skipping one level. When grouting leakage occurs during the grouting process, methods such as low pressure, thick slurry, small pump volume, and intermittent grouting should be used for treatment; when the intermittent grouting method needs to be used for construction, intermittent water pressure should be carried out each time when the injection stops to prevent the grouting pipeline from being blocked during the next grouting.

[0075] Among them, for the grouting slurry, P.F 32.5R cement, Class III fly ash, L-330-37 type water glass, a quick-setting controllable anti-dispersant (a paste-like quick-setting grouting material disclosed in Chinese Patent CN102001847A) and an underwater anti-dispersant (anti-dispersant - ANSP-0) are used for the mix proportion design of each area, and the mix proportion calculation method is the volume method.

[0076] Grouting sequence: First, grout and fill Area I to form a curtain grout stop wall. After the curtain grout stop wall in Area I is formed, grout and fill Area II from low to high and from both sides to the middle. Then, grout and fill Area VI. After that, grout and fill Area III to form a curtain grout stop wall. After the curtain grout stop wall in Area III is formed, grout and fill Area IV to form a partition wall. The distance between adjacent partition walls is 50 m. After the partition wall is formed, grout and fill Area V.

[0077] Among them, for Area I, cement-sodium silicate double-fluid slurry is used for grouting. The water-cement ratio of the cement-sodium silicate double-fluid slurry is 0.6, and the volume ratio of the cement slurry to the sodium silicate slurry is 3:1;

[0078] For Area II, cement-fly ash slurry is used for grouting. The water-binder ratio of the cement-fly ash slurry is 0.6, and the volume dosage of fly ash is 20% of the volume of the cement-fly ash slurry;

[0079] In Areas III and IV, quick-setting and controllable underwater anti-dispersant slurry is used for grouting. The water-binder ratio of the quick-setting and controllable underwater anti-dispersant slurry is 0.6, and the volume content of the quick-setting and controllable anti-dispersant is 25% of the volume of the quick-setting and controllable underwater anti-dispersant slurry. Considering the high price of the quick-setting and controllable anti-dispersant, in Areas III and IV, the bottom part is grouted with the quick-setting and controllable underwater anti-dispersant slurry, and the part above the bottom is grouted with a cement-sodium silicate-anti-dispersant double-fluid slurry. The water-binder ratio of the cement-sodium silicate-anti-dispersant double-fluid slurry is 0.6, the volume content of sodium silicate is 25% of the volume of the cement-sodium silicate-anti-dispersant double-fluid slurry, and the volume content of the anti-dispersant (referring to anti-dispersant-ANSP-0) is 1% of the volume of the cement-sodium silicate-anti-dispersant double-fluid slurry. When slurry leakage occurs locally in Area III and the grouting pressure cannot rise, a 50-fold boundary swelling grout plug is used for plugging. This material swells when it meets water and can achieve a good plugging effect, with a dosage of 250 kg per cubic meter.

[0080] In Area V, underwater anti-dispersant slurry is used for grouting. The underwater anti-dispersant slurry is a cement-fly ash slurry plus an underwater anti-dispersant. The water-binder ratio of the underwater anti-dispersant slurry is 0.6, the volume content of fly ash is 20% of the volume of the underwater anti-dispersant slurry, and the volume content of the underwater anti-dispersant is 1% of the volume of the underwater anti-dispersant slurry.

[0081] In Area VI, neat cement slurry is used for grouting. The water-binder ratio of the neat cement slurry is 0.6.

[0082] J) End of grouting: When the unit grouting volume is less than 70 L / min under the designed pressure and remains stable for more than 15 minutes, the grouting terminates. In addition, the goaf (upper half area) above elevation +400 m is a large-scale cavity structure. During the grouting process, the slurry can smoothly enter the goaf, but the slurry diffusion range is large and the stacking height is limited. To reach the final grouting pressure of 2 - 3 MPa, the slurry stacking height needs to exceed the orifice. Therefore, the grouting effect is verified through boreholes, and the termination condition of grouting is not controlled by the final hole pressure.

[0083] (6) Hole sealing: When using the upward grouting method, intermittent grouting is required. When there is no risk of pipe burial, the grout plug does not need to be lifted. When there is a risk of pipe burial, the grout plug should be lifted and the pipeline should be flushed. After intermittent grouting, re-grouting is carried out until the grouting end standard is reached, and then the hole sealing process is entered. After the grouting of the entire hole is completed, the grout plugging facility is pulled out, and thick cement slurry is poured into the hole from the orifice. After the slurry reaches the orifice, the hole sealing is completed.

[0084] (7) Grouting quality inspection: The inspection of grouting effect is carried out 1 month after the completion of grouting construction, and four methods are used for comprehensive analysis and judgment: First, the grouting effect is detected by drilling holes in the repaired roadway, and the grouting filling rate is not less than 90%; Second, 10% of the grouting holes are cored to determine the rock strength, and the uniaxial compressive strength of the stone is not less than 2 MPa; Third, inspection holes are drilled to measure the ultrasonic propagation velocity of the grouting-reinforced goaf; Fourth, statistical analysis of the grouting volume of the divided-area drilling holes.

[0085] a) Detection hole layout: Inspection holes are constructed towards the roof side in the repaired rock roadway, and the total number of detection holes is not less than 2% of the total number of grouting holes.

[0086] b) Detection standards:

[0087] ① Borehole detection: Inspection holes are constructed within the scope of goaf treatment. According to the "Technical Rules for Highway Design and Construction in Goaf Areas" (JTG / TD31-03-2011), the hole diameter is not less than 91 mm, and the extraction rate each time is greater than 90%. For the stone bodies obtained from the boreholes, they are soaked in clean water at 20°C ± 5°C for 40 - 48 h, and immediately tested after being taken out of the water. Referring to the "Technical Rules for Highway Design and Construction in Goaf Areas" (JTG / TD31-03-2011), the uniaxial compressive strength of the grouting stone bodies in the goaf is not less than 2.0 MPa. If it is found that the stone rate does not meet 90% or the stone strength is less than 2 MPa, supplementary grouting shall be carried out immediately until it is verified to be qualified.

[0088] ② Geophysical prospecting method: Comprehensive logging is carried out using ultrasonic or high-power sonic instruments before and after grouting. Referring to the "Code for Seismic Design of Buildings", it is required that the average shear wave (transverse wave) velocity in the grouting treatment section of the borehole > 350 m / s.

[0089] ③ Grouting detection: The conditions for the end of grouting are that the amount of grout injected into the hole per unit time is less than 50 L / min, the grouting duration is 15 - 20 min, and the final hole pressure is 2 - 3 MPa.

[0090] In this way, in this embodiment, the inclined long-distance drilling grouting of more than 100 m is realized for the steeply inclined coal mine goaf under the tunnel, and the problem of underwater grouting below the elevation of +400 m is effectively solved. The influence of the goaf in the deep stratum on the strength of the shallow foundation soil is reduced, the differential settlement amount is reduced, the overall performance of the foundation rock and soil mass is improved, the safe operation of the railway and social harmony and stability are ensured, and it provides a reference for the treatment of similar steeply inclined goafs under tunnels.

[0091] The above are only embodiments of the present invention. The invention is not limited to the fields involved in this embodiment. Common knowledge such as specific structures and characteristics known in the art is not described in detail here. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention belongs before the filing date or the priority date, can learn all the existing technologies in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the present invention. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A method for treating a steeply inclined coal mine goaf under a tunnel, characterized by: The following steps are involved: (1) Zoning of goaf treatment area: The goaf treatment area is divided into the upper and lower areas. The lower area is for underwater grouting. The upper area is divided into areas I, II and VI, and the lower area is divided into areas III, IV and V. (2) Drilling arrangement: Curtain holes are arranged in zones I, III and IV with a spacing of 10 m between them; grouting holes are arranged in zones II, V and VI in a plum blossom shape with a spacing of 20 m; the drilling inclination angle between curtain holes and grouting holes is 48° to 62°, and the drilling length is 25 to 180 m; (3) Drilling construction: a) Use a total station to locate and mark the ground or arch of the drilling site, lay out the drilling points, measure the drilling rig position, determine the azimuth, use a tracker to locate the inclination, and use a hole-opening orienteering instrument to locate the azimuth and check the inclination; b) Use rotary drilling rigs for drilling. The deviation between the drilled hole and the designed hole position should not be greater than 0.5m. The deviation of special hole positions should not be greater than 0.1m. The borehole should be measured every 50m, and the hole inclination should not exceed 1° per 100m. c) When drilling grouting holes and curtain holes to the fissure zone or the falling zone, use clean water to drill. If there is leakage or drill bit falling during drilling, records should be kept. If there is hole collapse or drill bit buried during drilling, analyze the cause in time, find out the situation, and use pipe drilling or grouting treatment before drilling; d) After drilling, the borehole should be flushed, and the sediment at the bottom of the hole should not block the effective grouting area. When the drilling operation is temporarily suspended and before the final hole is grouted, the hole mouth should be covered for protection; (4) Grouting: First, grouting is performed in zone I to form a curtain grouting wall. After the curtain grouting wall of zone I is formed, grouting is performed in zone II from low to high and from both sides to the middle. Then, grouting is performed in zone VI. Then, grouting is performed in zone III to form a curtain grouting wall. After the curtain grouting wall of zone III is formed, grouting is performed in zone IV to form a partition wall. After the partition wall is formed, grouting is performed in zone V. Among them, cement-water glass double liquid slurry is used for grouting in Zone I, the water-cement ratio of cement-water glass double liquid slurry is 0.6, and the volume ratio of cement slurry to water glass slurry is 3:1; cement-fly ash slurry is used for grouting in Zone II, the water-binder ratio of cement-fly ash slurry is 0.6, and the volume content of fly ash is 20% of the volume of cement-fly ash slurry; rapid-setting controllable underwater anti-dispersion slurry is used for grouting in Zone III and Zone IV, the water-binder ratio of rapid-setting controllable underwater anti-dispersion slurry is 0.6, and the volume content of fly ash is 20% of the volume of cement-fly ash slurry. The volume content of the quick-setting controllable anti-dispersion agent is 25% of the volume of the quick-setting controllable underwater anti-dispersion slurry; the underwater anti-dispersion slurry is used for grouting in the V area, and the underwater anti-dispersion slurry is cement fly ash slurry plus underwater anti-dispersion agent, the water-binder ratio of the underwater anti-dispersion slurry is 0.6, the volume content of fly ash is 20% of the volume of the underwater anti-dispersion slurry, and the volume content of the underwater anti-dispersion agent is 1% of the volume of the underwater anti-dispersion slurry; the cement pure slurry is used for grouting in the VI area, and the water-binder ratio of the cement pure slurry is 0.6; Grouting is terminated when the unit grouting volume is less than 70L / min and is stable for more than 15min under the specified pressure. The serous stone rate in each area is not less than 85%, and the serous stone strength is not less than 2MPa; (5) Sealing the hole: After the full hole grouting is completed, the grouting stop facility is pulled out and thick cement slurry is poured into the hole from the hole mouth. The hole is sealed when the slurry reaches the hole mouth.

2. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1 is characterized by: In step (3), before step a), the coal seam trend is first detected by horizontal drilling, and the horizontal distance from the borehole to the coal seam, the azimuth, the theoretical inclination of the final hole coordinates, and the theoretical borehole length are calculated; The coal seam inclination angle θ can be known from the drawings. The horizontal distance from the coal seam to the drilling site is located by drilling a horizontal hole in the drilling site, and the distance is calculated as X1. The height difference is calculated by the final hole elevation and the drilling site elevation, and the height difference is calculated as h. Through the trigonometric function relationship, formula (1-1) is constructed to calculate the distance X2 from the drilling site projection zone to the coal seam on the final hole plane; according to the design instructions, the distance between the empty spaces can be known, and the distance is calculated as d. The projection length l of the hole on the final hole plane is calculated by formula (1-2), and the inclination angle θ is calculated by formula (1-3) 倾 , the horizontal angle θ is calculated by formula (1-4) 水 ; The above-mentioned geometric calculation can be reviewed with the coordinate calculation, and the reliability of the data can be verified by the review calculation; Houdini modeling software is used to simulate the spatial arrangement of drilling holes, and the drilling hole positions can be optimized and adjusted in time; 3. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1 is characterized by: In step (3), when the hole deviation exceeds 1° per 100 meters, hole deviation correction is required: a) Grouting and plugging to re-drill holes and sweep the inclination: cement plus triethanolamine composite admixture is used as the plugging material, with a water-cement ratio of 0.75:1 to 0.6:1; the plugging hole inclination pressure is maintained for 20 minutes after reaching the final pressure. If the final pressure cannot be reached, long-term maintenance is required; after maintenance, light pressure and slow rotation are used to sweep the inclination. Normal drilling can only be resumed when the inclination and azimuth of the new hole drilled meet the requirements; b) Sweeping: Use a drilling bit with more blades to slowly sweep the hole from the top of the deflected area downwards. Prevent it from slipping when encountering steps; c) Expansion: Use a drill bit larger than the original one to enlarge the hole diameter, correct the hole, expand it to the original depth and then use the original drill bit again, suspend the drill tool about 1m, slowly lower it to drill a new hole, drill 1~2m and pass the inclination test, then switch to normal drilling; d) Shoveling: From the upper part of the deviated part, use a weighted tube with a shoveling drill bit to scrape off the deviated part with the force of vertical impact. Each stroke is about 2m. Rotate the drill bit while shoveling. After shoveling one or two circles, make the second stroke. After shoveling out the step, use the reaming drill bit to expand the shoveled section. Alternate shoveling and expanding until it can no longer be shoveled, and then expand the hole to the bottom. When shoveling the hole, pay attention to aligning the three points in a straight line to prevent the center from deviating and affecting the shoveling hole.

4. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1 is characterized by: In step (4), when slurry leakage occurs locally in zone III, a 50-fold boundary expansion stop pad is used for plugging.

5. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1 is characterized by: In step (4), the bottom of zone III and zone IV is grouted with a quick-setting controllable underwater anti-dispersion slurry, and the area above the bottom of zone III and zone IV is grouted with a cement-water glass-anti-dispersion double liquid slurry. The water-cement ratio of the cement-water glass-anti-dispersion double liquid slurry is 0.6, the volume content of water glass is 25% of the volume of the cement-water glass-anti-dispersion double liquid slurry, and the volume content of the anti-dispersion agent is 1% of the volume of the cement-water glass-anti-dispersion double liquid slurry.

6. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1, characterized in that: In step (4), the grouting pressure is ≥1MPa.

7. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1, characterized in that: In step (4), the distance between adjacent partition walls is 50m.

8. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 1, characterized in that: The following steps are also included: (6) Grouting quality inspection: The grouting effect inspection is carried out one month after the grouting construction is completed, and four methods are used for comprehensive analysis and judgment: first, the grouting effect is inspected by drilling holes in the repair tunnel, and the grouting filling rate is not less than 90%; second, the rock strength is measured by coring 10% of the grouting holes, and the uniaxial compressive strength of the stone is not less than 2MPa; third, the ultrasonic propagation velocity of the grouting reinforcement goaf is measured by drilling inspection holes; fourth, the grouting volume of the zoned drilling holes is statistically analyzed.

9. The method for treating the goaf of a steeply inclined coal mine under a tunnel according to claim 8, characterized in that: The specific operation position of drilling inspection holes to measure the ultrasonic propagation velocity of the goaf area for grouting reinforcement is as follows: before and after grouting, ultrasonic or high-power sonic instrument is used for comprehensive measurement, and the average shear wave (transverse wave) velocity of the grouting treatment section in the borehole is required to be greater than 350m / s; When conducting statistical analysis on the grouting volume of zoned boreholes, the termination conditions are as follows: the volume of slurry injected into the hole per unit time is less than 50L / min, the grouting duration is 15 to 20 minutes, and the final hole pressure is 2 to 3MPa.

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