Method for determining early strength collapse prevention grouting and drilling detection in old goaf

Abstract

The present invention discloses an early-strength collapse-preserving grouting and borehole detection determination method for old goaf areas, and relates to the technical field of repairing old goaf areas in mines. The method comprises: drilling grouting boreholes and detection boreholes on the ground, preparing early-strength collapse-preserving slurry, placing a sonar detector at the bottom of the detection borehole to detect signals, and recording them as the first magnetic field signal; injecting early-strength collapse-preserving slurry into the grouting borehole, and after stopping the grouting, detecting and receiving the signal again through the sonar detector, recording it as the last magnetic field signal, and fitting the overall distribution map of the goaf magnetic field under the signal; combining theoretical knowledge to calculate the maximum radius value of a grouting; and finally obtaining the optimal borehole spacing value according to the maximum radius value. The method of the present invention utilizes industrial solid waste discharged after refining alumina from bauxite, and while effectively responding to the grouting filling of goaf areas, it also lays an important foundation for related research such as the flow law of grouting in goaf areas.

Description

Technical Field

[0001] The invention relates to the technical field of repairing and managing old goaf areas in mines, and in particular to an early-strength collapse-preserving grouting and drilling detection determination method for old goaf areas. Background Art

[0002] The old goaf areas formed underground after coal mining, the generation and existence of this adverse geological body pose a serious threat to the safe construction and stable operation of surface buildings (structures). Coal mining subsidence area refers to the area where the surface subsidence depth is greater than 10mm due to coal mining. The agricultural land in the coal mining subsidence area that has reduced or no production due to underground coal mining, as well as the affected construction land and unused land are called coal mining subsidence areas. At present, the problems of limited space for transformation and development and insufficient construction land in most mining cities are becoming increasingly prominent. It is urgent to carry out the construction and utilization of coal mining subsidence areas, ensure the supply of urban construction land, and promote urban transformation and development.

[0003] When treating old goafs, grouting filling is used as one of the treatment methods. The current difficulties mainly lie in the fact that the optimal grouting radius for old goafs is still unclear, resulting in inappropriate spacing of drilling holes. In addition, the flow process and state of the slurry in the goaf are difficult to accurately judge, making it difficult to control the amount of grouting during the grouting process, which can easily lead to insufficient slurry injection, causing the formation to remain in an unstable state, or excessive slurry injection, increasing the cost of project investment.

[0004] In summary, the design of grouting holes is particularly critical when repairing and managing old goaf areas. Summary of the invention

[0005] The purpose of the present invention is to provide a method for early-strength collapse-preserving grouting and drilling detection determination in old goaf areas. This method introduces a filling material that can timely produce early strength and collapse preservation, and can judge the grouting effect and the effective diffusion radius of grouting during the grouting process, thereby laying an important foundation for the study of the flow laws of grouting in goaf areas in mining projects.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for early-strength collapse-preserving grouting and drilling detection in old goaf areas comprises the following steps in sequence:

[0008] a. Determine the ground position corresponding to the central axis of the old goaf tunnel according to the geological data above and below the coal mine, and drill grouting holes on the ground;

[0009] b. According to the direction of the tunnel in the old goaf, a detection borehole is drilled on one side of the grouting borehole along the direction, and the distance between the detection borehole and the grouting borehole is 30 to 50 meters;

[0010] c. preparing an early-strength collapse-preserving slurry, wherein the raw materials used in the early-strength collapse-preserving slurry include cement, fly ash, red mud, a composite activator, a water reducing agent, an early-strength agent, a collapse-preserving agent and water;

[0011] d. placing a sonar detector at the bottom of the detection borehole, turning on the sonar detector, detecting and receiving signals, and recording them as the first magnetic field signal; moving the sonar detector to enable it to scan the entire space of the goaf, transmitting the obtained information to a host on the ground through signals, storing the records in the ground host, fitting the overall sonar distribution of the goaf according to the sound waves, and fitting the overall magnetic field distribution map of the goaf in combination with theoretical knowledge;

[0012] e. Inject early-strength collapse-preserving slurry into the grouting borehole, and stop grouting when the grouting pressure reaches the grouting limit and the sonar detector detects that the sound wave no longer has a significant change;

[0013] f. Detect and receive the signal again through the sonar detector, record it as the last magnetic field signal, and fit the overall distribution map of the magnetic field in the goaf under the signal;

[0014] g. Compare the magnetic field distribution diagrams of the goaf area obtained in step d and step f, and calculate the maximum radius value of a grouting operation;

[0015] h. Twice the maximum radius of the first grouting in step g is the optimal drilling hole spacing value;

[0016] i. According to the optimal borehole spacing value described in step h, drill the second grouting borehole, the third grouting borehole...the Nth grouting borehole in sequence, and complete the repair of the goaf by injecting early-strength collapse-preserving slurry into each grouting borehole.

[0017] As a preferred solution of the present invention, the diameter of the grouting borehole and the detection borehole is the same, and the diameter is 250-300 mm.

[0018] As another preferred embodiment of the present invention, in step c, the composite activator is composed of CaO and CaSO 4 Composition, by mass ratio, CaO:CaSO 4 =1:1.5; the collapse retaining agent is a main side chain graft density improved type, a carboxylic acid protected type, a cross-linked type or an amphoteric type.

[0019] Preferably, in step c, the mass ratio is: cement: fly ash: red mud: composite activator: water reducing agent = 1:3.5:4.7:0.5:0.1.

[0020] Preferably, in step d, the dynamic monitoring time interval of the sonar detector is 5 to 10 minutes.

[0021] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0022] (1) The present invention proposes a method for early-strength collapse-preventing grouting and drilling detection in old goaf areas. The early-strength collapse-preventing slurry selected in the method contains red mud, which solves the problem of industrial solid waste discharged after refining alumina from bauxite and protects the environment.

[0023] (2) The early strength and collapse-preventing slurry can reach early strength in a short time after the old goaf is filled. Construction can be carried out on the filled old goaf as early as possible, which can achieve ecological management of the old goaf and shorten the ground construction time. In addition, the addition of the collapse-preventing agent ensures the long-term stability of the overlying rock strata in the goaf.

[0024] (3) The sonar wave detection can accurately determine the maximum grouting range of the actual grouting area, and then determine the distance between the left and right drilling holes, to ensure that the grouting material fills the goaf to the greatest extent and reduce the waste of drilling and filling materials.

[0025] (4) The present invention directly injects grout into the tunnel of the old goaf, which is easier to implement and control than injecting grout into the overlying rock strata in the goaf. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings:

[0027] Figure 1 This is a schematic diagram of the optimal drilling arrangement of the present invention;

[0028] Figure 2 is a flow chart of the method of the present invention;

[0029] In the figure:

[0030] 1. Grouting drilling, 2. Detection drilling, 3. Eye cutting, 4. Slope, 5. Sonar detector, 6. Inspection station. DETAILED DESCRIPTION

[0031] The present invention proposes an early-strength collapse-preserving grouting and drilling detection determination method for old goaf areas. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is specifically described below in conjunction with specific embodiments.

[0032] like Figure 2 As shown, the present invention proposes a method for fluidized filling grouting detection and optimal drilling arrangement in old goaf areas, and the specific steps are as follows:

[0033] Step 1: Determine the ground position corresponding to the central axis of the goaf tunnel according to the geological data above and below the coal mine, and drill a grouting hole on the ground with a diameter of 250mm;

[0034] Step 2: According to the direction of the old goaf roadway, drill a detection hole on one or both sides of the grouting borehole along the direction. The distance between the detection hole and the grouting hole is 50m, and the diameter of the detection hole is 250mm.

[0035] Step 3, preparing early strength and collapse-preserving slurry;

[0036] The raw materials used for the early-strength and collapse-preventing slurry include: cement, fly ash, red mud, composite activator, water reducing agent, early-strength agent, collapse-preventing agent and water. All the raw materials are mixed and stirred, and the early-strength and collapse-preventing slurry is made by stirring evenly.

[0037] Among the above raw materials, according to the mass ratio:

[0038] Cement: fly ash: red mud: composite activator: water reducer = 1:3.5:4.7:0.5:0.1, of which the solid mass fraction is 74%.

[0039] The composite activator is composed of CaO and CaSO 4 Composition, CaO:CaSO 4 =1:1.5; the water reducer is analytical grade naphthalene-based water reducer.

[0040] The dosage of early strength agent is 1% chloride salt, 2% sodium sulfate, 3% sodium sulfate and slow setting water reducing agent, and 0.05% triethanolamine in dry environment. In humid environment, 1.5% sodium sulfate and 0.05% triethanolamine.

[0041] The collapse-preserving agent can be a main-side chain graft density-modified type, a carboxylic acid-protected type, a cross-linked type, an amphoteric type, etc., such as hydroxypropyl acrylate, an amphoteric polycarboxylic acid type, etc.;

[0042] Step 4, record it as the first magnetic field signal; move the sonar detector to scan the entire space of the goaf, transmit the obtained information to the host on the ground through the signal, store the record in the ground host, fit the overall distribution of the goaf sonar according to the sound wave, and fit the overall distribution map of the goaf magnetic field in combination with theoretical knowledge; the time interval is 5 to 10 minutes;

[0043] Step 5: Inject early-strength collapse-preserving slurry into the grouting borehole, and stop grouting when the grouting pressure reaches the grouting limit and the sonar detector detects that the sound wave no longer has a significant change;

[0044] Step 6: Detect and receive the signal again through the sonar detector, record it as the last magnetic field signal, and fit the overall distribution map of the goaf magnetic field under the signal;

[0045] Step 7, comparing the magnetic field distribution diagrams of the goaf area obtained in step 4 and step 6, and calculating the maximum radius value of a grouting operation;

[0046] Step 8: Twice the maximum radius of a grouting operation in step 6 is the optimal drilling hole spacing value;

[0047] Step nine: according to the optimal borehole spacing value described in step eight, drill the second grouting borehole, the third grouting borehole ... the Nth grouting borehole in sequence, and complete the filling of the goaf by injecting fluidized filling slurry into each grouting borehole.

[0048] The red mud in the above-mentioned early-strength collapse-preserving slurry comes from industrial solid waste discharged after refining alumina from bauxite, thus completing the utilization of solid waste.

[0049] Embodiment 1:

[0050] Take a coal mine as an example. Figure 1 As shown, the figure shows a grouting borehole 1, a detection borehole 2, a cut hole 3, a drift 4, a sonar detector 5, and a detection station 6. The method of the present invention is used, and the specific steps are as follows:

[0051] Step 1: According to the geological data of the coal mine, fluidized grouting is carried out on the old goaf of the 4# coal seam in the mine, the ground position corresponding to the centerline of the goaf is determined, and a grouting hole is drilled on the ground corresponding to the middle of the goaf. The diameter of the grouting hole is 250mm.

[0052] According to the direction of the old goaf, detection holes are drilled on both sides of the grouting hole along the direction. The distance between the detection hole and the grouting hole is 50m, and the diameter of the detection hole is 250mm.

[0053] Step 2: Prepare early strength and collapse-proof slurry

[0054] The raw materials used for the early-strength and collapse-preventing slurry include: cement, fly ash, red mud, composite activator, water reducing agent, early-strength agent, collapse-preventing agent and water. All the raw materials are mixed and stirred, and the early-strength and collapse-preventing slurry is made by stirring evenly.

[0055] Among the above raw materials, according to the mass ratio:

[0056] Cement: fly ash: red mud: composite activator: water reducer = 1:3.5:4.7:0.5:0.1, of which the solid mass fraction is 74%.

[0057] The composite activator is composed of CaO and CaSO 4 Composition, CaO:CaSO 4 =1:1.5; the water reducer is analytical grade naphthalene-based water reducer.

[0058] The dosage of early strength agent is 1% chloride salt, 2% sodium sulfate, 3% sodium sulfate and slow setting water reducing agent, and 0.05% triethanolamine in dry environment. In humid environment, 1.5% sodium sulfate and 0.05% triethanolamine.

[0059] Hydroxypropyl acrylate is used as the collapse-preventing agent;

[0060] Step 3: Place the sonar detector at the bottom of the detection borehole, turn on the sonar detector, detect and receive signals, and record them as the first magnetic field signal; move the sonar detector to enable it to scan the entire space of the goaf, transmit the obtained information to the host on the ground through signals, store and record, and fit the overall distribution map of the goaf magnetic field in combination with theoretical knowledge; during the grouting process, the sonar detector performs dynamic detection at a time interval of 10 minutes;

[0061] Step 4: inject early strength collapse-preserving slurry into the grouting borehole, and stop grouting when the grouting pressure reaches the grouting limit and the sonar detector detects that the magnetic field no longer has a significant change;

[0062] Step 5: Detect and receive the signal again through the sonar detector, record it as the last magnetic field signal, and fit the overall distribution map of the magnetic field in the goaf under the signal;

[0063] Step 6: Compare the magnetic field distribution diagrams of the goaf obtained in step 3 and step 5, and calculate that the maximum radius of a grouting is 20m;

[0064] Step 7: To ensure the grouting effect, take twice the maximum radius of the grouting in step 6 as the optimal drilling hole spacing;

[0065] Step 8. According to the optimal borehole spacing value described in step 7, drill the second grouting borehole, the third grouting borehole...the Nth grouting borehole in sequence, and complete the filling of the goaf by injecting fluidized filling slurry into each grouting borehole.

[0066] Effect:

[0067] The ground in the area was monitored during the grouting process of the old goaf of the coal mine and during the construction of the building. At the five measuring points on the west side of the data processing center, the ground gradually rose during the grouting project and dropped again after the grouting was completed. With the construction of the central building, the ground sank. When the second floor of the building was completed (300 days after the completion of the grouting reinforcement of the goaf), the ground sank by a maximum of 6 mm, the elevation change tended to be gentle, and the average settlement rate was 0.011 mm / d, which met the relevant requirements of the "Code for Measurement of Building Deformation". It is believed that the ground deformation has entered a stable stage.

[0068] Parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0069] It should be further noted that the specific embodiments described herein are merely examples of the spirit of the present invention. A person skilled in the art of the present invention may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but this will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for determining early strength collapse prevention grouting and drilling detection in old goaf areas, It is characterized in that The following steps are included in sequence: Step a: Determine the ground position corresponding to the central axis of the old goaf tunnel according to the geological data above and below the coal mine, and drill grouting holes on the ground; Step b: according to the direction of the old goaf roadway, drilling a detection borehole on one side of the grouting borehole along the direction, the distance between the detection borehole and the grouting borehole is 30-50m; Step c: preparing an early strength and collapse-preserving slurry, wherein the raw materials used in the early strength and collapse-preserving slurry include cement, fly ash, red mud, composite activator, water reducing agent, early strength agent, collapse-preserving agent and water; Step d: placing a sonar detector at the bottom of the detection borehole, turning on the sonar detector, detecting and receiving signals, and recording them as the first magnetic field signal; moving the sonar detector to enable it to scan the entire space of the goaf, transmitting the obtained information to a host on the ground through signals, storing the records in the ground host, fitting the overall sonar distribution of the goaf according to the sound waves, and fitting the overall magnetic field distribution map of the goaf in combination with theoretical knowledge; Step e: injecting early strength collapse-preserving slurry into the grouting borehole, and stopping grouting when the grouting pressure reaches the grouting limit and the sonar detector detects that the sound wave no longer has a significant change; Step f: Detect and receive the signal again through the sonar detector, record it as the last magnetic field signal, and fit the overall distribution map of the magnetic field of the goaf under the signal; Step g: Compare the goaf area magnetic field distribution diagrams obtained in step d and step f, and calculate the maximum radius value of a grouting operation; Step h: twice the maximum radius of the grouting in step g is the optimal drilling hole spacing; Step i: According to the optimal borehole spacing value described in step h, drill the second grouting borehole, the third grouting borehole...the Nth grouting borehole in sequence, and complete the repair of the goaf by injecting early-strength collapse-preserving slurry into each grouting borehole.

2. According to the method for early strength collapse prevention grouting and drilling detection in old goaf area described in claim 1, Features: In step a, the grouting borehole and the detection borehole have the same aperture, which is 250-300 mm.

3. The method for early-strength collapse-preserving grouting and drilling detection in old goaf according to claim 1, Features: In step c, the composite activator consists of CaO and CaSO 4 and, by mass ratio, CaO:CaSO 4 = 1:1.5; the slump retaining agent is a main side chain graft density improved type, carboxylic acid protection type, crosslinked type or amphoteric type.

4. The method for early strength collapse prevention grouting and drilling detection in old goaf according to claim 1, Features: In step c, the mass ratio is: cement: fly ash: red mud: composite activator: water reducing agent = 1:3.5:4.7:0.5:0.

1.

5. The method for early-strength collapse-preserving grouting and drilling detection in old goaf according to claim 1, Features: In step d, the dynamic monitoring time interval of the sonar detector is 5 to 10 minutes.

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