Gob-side entry retaining high-strength filling and low-strength sealing structural filling process

Abstract

The invention discloses a gob-side entry retaining high-strength filling and low-strength sealing structural filling process which specifically comprises the following steps: S1, construction preparation: acquiring geological parameters, pre-burying an optical fiber sensor array in a roadside area, connecting to a mining explosion-proof control box, and then premixing dry materials according to a high-strength filling material ratio, S2, high-strength filling, S3, low-strength sealing, S5, high-strength filling and S6, low-strength sealing. And S4, dynamic regulation and maintenance. The invention relates to the technical field of coal mine underground gob-side entry retaining support. According to the gob-side entry retaining high-strength filling and low-strength sealing structural filling process, the high-strength filling body guarantees structural stability in the high mine pressure stage, the low-strength sealing layer improves leakproofness in the stable stage, the service life of a roadway is prolonged, the material performance is adjusted in real time through an optical fiber sensing and mechanical model, excessive supporting or insufficient sealing is avoided, and the working efficiency is improved. And extra sealing layer construction is reduced, the material and labor cost is reduced, the secondary fracture risk of the top plate is effectively controlled, and gas leakage and surrounding rock instability accidents are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of gob-side entry retaining support in coal mines, and specifically to a high-strength filling and low-strength sealing structural filling process for gob-side entry retaining. Background Art

[0002] Gob-side entry retaining is an important technical means for efficient coal mining. Its core lies in controlling the movement of roof strata through the gob-side filling body to maintain the stability of the roadway. Traditional filling processes mostly use single-strength materials, which are difficult to adapt to the dynamic changes of mine pressure during the mining process, resulting in the following problems:

[0003] 1. Strong mine pressure stage: When the strength of the filling body is insufficient, structural instability is likely to occur, leading to secondary fracture or even collapse of the roof.

[0004] 2. Stable stage: The high-strength materials have too high rigidity and cannot adapt to the stress release of the surrounding rock, resulting in poor airtightness and an increased risk of gas leakage in the gob area.

[0005] 3. Material waste: The single-strength design cannot balance the requirements of support and sealing, and additional sealing layers need to be constructed, increasing costs.

[0006] Existing technologies (such as high-water material filling) can solidify quickly, but lack a dynamic performance regulation mechanism and cannot achieve phased performance optimization. Summary of the Invention

[0007] (1) Technical problems to be solved

[0008] In view of the deficiencies of the existing technologies, the present invention provides a high-strength filling and low-strength sealing structural filling process for gob-side entry retaining, which solves the problems that the traditional filling process cannot effectively respond to the dynamic changes of mine pressure during the mining process, resulting in difficulty in balancing support and sealing performance, the single-strength filling material is prone to instability in the strong mine pressure stage, and is prone to insufficient airtightness due to excessive rigidity in the stable stage, and lacks real-time monitoring means and cannot ensure the coordinated operation of the high- and low-strength material interfaces.

[0009] (2) Technical solutions

[0010] To achieve the above objectives, the present invention is realized through the following technical solutions: A high-strength filling and low-strength sealing structural filling process for gob-side entry retaining specifically includes the following steps:

[0011] S1. Construction preparation: Collect geological parameters, embed an optical fiber sensor array in the gob-side area, connect it to a mining explosion-proof control box, and then premix the dry materials according to the ratio of the high-strength filling materials, and add 12% bentonite to the sealing materials.

[0012] S2. High-strength filling: Use a double-fluid grouting pump to inject high-water materials with a water-cement ratio of 1.4:1 into the side of the roadway. The width of the filling body is set to 3.0 m. Real-time feedback of strain data is obtained through fiber optic sensors to ensure that the compressive strength after 28 days is ≥12 MPa, thereby forming a high-strength filling body. Then, apply an interface agent on the surface of the high-strength filling body to enhance the bonding force with the sealing layer.

[0013] S3. Low-strength sealing: After the mine pressure stabilizes, adjust the water-cement ratio to 1.5:1, and pump low-strength materials to cover the high-strength filling body with a thickness of 0.5 m. Analyze the interface cracks using the fiber optic reflection signal. If the crack width > 0.2 mm, automatically increase the bentonite content to 15%. Support the sealing layer through wear-resistant pads and allow a compression of 5%-8% with the deformation of the surrounding rock.

[0014] S4. Dynamic regulation and maintenance: The mine control box generates stress-strain curves every 24 hours, and manually review abnormal data. If the strength of the sealing layer is lower than 8 MPa, increase the cement content by 5%-10% through the feedback execution module. After the danger is lifted, reset the sensor system through the control terminal and enter the next cycle.

[0015] Preferably, the specific ratio of the high-strength filling material in step S1 is: sulfoaluminate cement: fly ash: coagulant = 1:0.6:0.05.

[0016] Preferably, the interface agent in step S2 is epoxy resin.

[0017] Preferably, the wear-resistant pads in step S3 are made of polytetrafluoroethylene.

[0018] Preferably, the thickness of the wear-resistant pads is 10 mm, and the contact surface with the filling body is provided with anti-slip patterns with a depth of 1 mm.

[0019] Preferably, the fiber optic sensor array is arranged along the height direction of the filling body, and a set is installed every 0.5 m to monitor the strain of the filling body and the interface stress distribution in real time. The outer layer of the fiber optic sensor array is coated with an explosion-proof sheath, and the sheath material is polyurethane with a pressure resistance level ≥10 MPa.

[0020] Preferably, the feedback execution module can dynamically adjust the water-cement ratio of the pumped material according to the sensor data, and the control range is ±0.1. Analyze the crack width of the interface between the high-strength and low-strength materials through the fiber optic reflection signal, and the threshold is set to 0.2 mm. When the threshold is exceeded, an alarm is triggered and the ratio is automatically corrected.

[0021] Preferably, the mechanical model and parameter design module is based on the characteristics of the secondary fracture of the roof, establishes a coupling model of the surrounding rock and the filling body, and calculates the roof cutting resistance:

[0022]

[0023] In the formula: α is the dip angle of the coal seam; L is the length of the rock block; q is the self-weight per unit length of the rock block, h is the thickness of the rock block, and ΔS C is the subsidence amount of the roof when the rock block is cut off;

[0024] Calculation of coal body abutment pressure:

[0025]

[0026] Among them, the width x of the stress limit equilibrium zone 0 , guiding the design of the filling body width.

[0027] Preferably, in the model, ΔS C The allowable value of the roof subsidence amount is 50 - 80 mm. When it exceeds, the width of the filling body needs to be increased.

[0028] Preferably, the parameters collected in the geological parameter collection in step S1 are: the dip angle of the coal seam α = 15°, the mining height M = 3.2 m, and the thickness of the immediate roof h = 2.1 m.

[0029] (III) Beneficial effects

[0030] The present invention provides a high-strength filling and low-strength sealed structural filling process for gob-side entry retaining. Compared with the prior art, it has the following beneficial effects:

[0031] (1). In this high-strength filling and low-strength sealed structural filling process for gob-side entry retaining, the high-strength filling body in the strong mine pressure stage ensures the structural stability, and the low-strength sealing layer in the stable stage improves the tightness, prolonging the service life of the roadway. The material properties are adjusted in real time through fiber optic sensing and mechanical models, avoiding over-support or insufficient sealing.

[0032] (2). This high-strength filling and low-strength sealed structural filling process for gob-side entry retaining reduces the construction of additional sealing layers, reduces material and labor costs, effectively controls the risk of secondary roof fracture, and reduces gas leakage and surrounding rock instability accidents. Description of the drawings

[0033] Figure 1 is the mechanical model diagram of gob-side entry retaining of the present invention;

[0034] Figure 2 is the whole process of the present invention from high-strength filling construction, low-strength sealing layer laying to real-time monitoring and feedback. Specific embodiments

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1-2 The embodiment of the present invention provides two technical solutions: a high-strength filling process along the gob-retained tunnel and a low-strength sealing structural filling process, which specifically include the following embodiments:

[0037] Embodiment 1: Specifically comprises the following steps:

[0038] S1. Construction preparation: geological parameter collection, pre-buried fiber optic sensor array in the tunnel area, connected to the mine explosion-proof control box, and then pre-mixed dry materials according to the proportion of high-strength filling materials, and added 12% bentonite to the sealing material;

[0039] S2, high-strength filling: a double-liquid grouting pump is used to inject high-water materials with a water-cement ratio of 1.4:1 into the side of the tunnel. The filling body width is set to 3.0m. The strain data is fed back in real time through the optical fiber sensor to ensure that the 28-day compressive strength is ≥12MPa, thus forming a high-strength filling body. Then, an interface agent is sprayed on the surface of the high-strength filling body to enhance the bonding force with the sealing layer.

[0040] S3, low-strength sealing: after the mine pressure stabilizes (30 days after mining), adjust the water-cement ratio to 1.5:1, pump low-strength materials to cover the high-strength filling body with a thickness of 0.5m, use the optical fiber reflection signal to analyze the interface cracks, if the crack width is greater than 0.2mm, automatically increase the bentonite content to 15%, support the sealing layer with wear-resistant pads, and allow it to produce 5%-8% compression as the surrounding rock deforms;

[0041] S4. Dynamic control and maintenance: The mining control box generates a stress-strain curve every 24 hours and manually verifies abnormal data. If the strength of the sealing layer is lower than 8MPa, the cement content is increased by 5%-10% through the feedback execution module. After the danger is eliminated, the sensor system is reset through the control terminal to enter the next cycle.

[0042] In the embodiment of the present invention, the specific ratio of the high-strength filling material in step S1 is: sulphoaluminate cement: fly ash: accelerator = 1:0.6:0.05.

[0043] In the embodiment of the present invention, the interface agent in step S2 is epoxy resin.

[0044] In the embodiment of the present invention, the wear-resistant pad in step S3 is made of polytetrafluoroethylene.

[0045] In the embodiment of the present invention, the wear-resistant pad has a thickness of 10 mm, and anti-slip lines are provided on the contact surface with the filling body, and the depth of the anti-slip lines is 1 mm.

[0046] Embodiment 2: The different technical solution of the present invention compared with Embodiment 1 is that the fiber optic sensor array is arranged along the height direction of the filling body, and a group is installed every 0.5 m to monitor the strain of the filling body and the interfacial stress distribution in real time. The outer layer of the fiber optic sensor array is coated with an explosion-proof sheath, and the sheath material is polyurethane, and the pressure resistance level is ≥10 MPa.

[0047] In the embodiment of the present invention, the feedback execution module can dynamically adjust the water-cement ratio of the pumped material according to the sensor data, and the control range is ±0.1. The crack width of the interface between the high-strength material and the low-strength material is analyzed through the fiber optic reflection signal, and the threshold is set to 0.2 mm. When the threshold is exceeded, an alarm is triggered and the mixing ratio is automatically corrected.

[0048] In the embodiment of the present invention, the mechanical model and parameter design module is based on the characteristics of the secondary fracture of the roof, establishes a coupling model of the surrounding rock and the filling body, and calculates the roof cutting resistance:

[0049]

[0050] In the formula: α is the coal seam dip angle; L is the length of the rock block; q is the self-weight per unit length of the rock block, h is the thickness of the rock block, and ΔS C is the subsidence of the roof when the rock block is cut;

[0051] Calculation of coal body abutment pressure:

[0052]

[0053] In the formula:

[0054] C 0 , —Cohesion and internal friction angle of the interface between the coal seam and the roof and floor rock strata;

[0055] α—Coal seam dip angle;

[0056] P x —Support resistance of the support to the coal rib;

[0057] A—Lateral pressure coefficient;

[0058] M—Mining height;

[0059] H—Mining depth;

[0060] γ—Average unit weight of overlying strata;

[0061] k—Stress concentration coefficient.

[0062] Calculation of the support resistance beside the roadway: Mechanical equations are established for the two rock blocks AB and BC respectively using the equilibrium method. For the BC rock block, in the direction perpendicular to the dip angle α, ΣF n = 0, we get:

[0063] N B -qcosα·e - N c = 0

[0064] In the direction parallel to the dip angle α, ∑F s = 0, we get:

[0065] T B = T C +qsinα·e

[0066] ∑M B = 0, we get:

[0067]

[0068] For the AB rock block, ∑M A = 0, we get:

[0069]

[0070] Where:

[0071] α—the dip angle of the coal seam;

[0072] c—the width of the roadway;

[0073] d—the width of the support beside the roadway;

[0074] h—the thickness of the main roof rock stratum;

[0075] P q —the roof cutting resistance of the support beside the roadway;

[0076] M L —the ultimate bending moment of the main roof rock stratum;

[0077] M 0 —the residual bending moment of the main roof at end A;

[0078] q—the self-weight per unit length of the main roof and the weak rock stratum above it;

[0079] q 0 —the self-weight per unit length of the immediate roof;

[0080] ΔS B —the subsidence amount of end B before the main roof caving,

[0081] and its calculation formula is:

[0082]

[0083] The length of the e—BC rock block, and its calculation formula is:

[0084]

[0085] In the formula:

[0086] b—the weighting interval of the basic roof;

[0087] L m —the length of the working face.

[0088] According to the analysis in Chapter 2, the specific geomechanical parameter values are as follows:

[0089] The 090515 working face is a fully mechanized top coal caving face. The average thickness of the coal seam is 4.1m, the mining height is 2.8m, the top coal caving height is 1.3m, the working face length is 204m, the periodic weighting interval is considered as 15m, the maximum buried depth of the roadway is 454m, the thickness of the immediate roof is 5.83m, the thickness of the basic roof is 7.18m, the unit weight of the overlying strata is 24kN / m 3 , the stress concentration coefficient is 2.0, the maximum tensile strength of the basic roof rock stratum is 2.4MPa, the lateral pressure coefficient is 0.5, the cohesion of the coal seam is 1.7MPa, the internal friction angle is 53.67°, the side is supported by twist drill rod bolts, and the support resistance is considered as 0.06MPa, and the coal seam dip angle is considered as an average of 4°. Substituting the above parameters into Equation (3-7), the cutting resistance of the backfill body in the 090515 track roadway is 19.19MN / m. During on-site construction, the overall strength of the backfill body is considered as 10MPa, and the theoretical value of the required width of the backfill body is 1.92m.

[0090] In the embodiment of the present invention, ΔS in the model C The allowable value of the roof subsidence is 50 - 80mm. When it exceeds, the width of the backfill body needs to be increased.

[0091] In the embodiment of the present invention, the parameters collected in step S1 for geological parameters are: the coal seam dip angle α = 15°, the mining height M = 3.2m, and the thickness of the immediate roof h = 2.1m are measured.

[0092] In summary, in the strong mine pressure stage of the present invention, the high-strength backfill body ensures the structural stability, and in the stable stage, the low-strength sealing layer improves the tightness, prolongs the service life of the roadway, adjusts the material properties in real time through optical fiber sensing and mechanical models, avoids over-support or insufficient sealing, reduces the construction of additional sealing layers, reduces material and labor costs, effectively controls the risk of secondary roof fracture, and reduces gas leakage and surrounding rock instability accidents.

[0093] At the same time, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0094] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0095] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-strength filling and low-strength sealing structural filling process along the gob-side entry retention, characterized in that: The specific steps include: S1. Construction preparation: geological parameter collection, pre-buried fiber optic sensor array in the tunnel area, connected to the mine explosion-proof control box, and then pre-mixed dry materials according to the proportion of high-strength filling materials, and added 12% bentonite to the sealing material; S2, high-strength filling: a double-liquid grouting pump is used to inject high-water materials with a water-cement ratio of 1.4:1 into the side of the tunnel. The filling body width is set to 3.0m. The strain data is fed back in real time through the optical fiber sensor to ensure that the 28-day compressive strength is ≥12MPa, thus forming a high-strength filling body. Then, an interface agent is sprayed on the surface of the high-strength filling body to enhance the bonding force with the sealing layer. S3, low-strength sealing: after the mine pressure stabilizes, adjust the water-cement ratio to 1.5:1, pump low-strength materials to cover the high-strength filling body with a thickness of 0.5m, use the optical fiber reflection signal to analyze the interface cracks, if the crack width is greater than 0.2mm, automatically increase the bentonite content to 15%, support the sealing layer with wear-resistant pads, and allow it to produce 5%-8% compression as the surrounding rock deforms; S4. Dynamic control and maintenance: The mining control box generates a stress-strain curve every 24 hours and manually verifies abnormal data. If the strength of the sealing layer is lower than 8MPa, the cement content is increased by 5%-10% through the feedback execution module. After the danger is eliminated, the sensor system is reset through the control terminal to enter the next cycle.

2. A high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1, characterized in that: The specific ratio of the high-strength filling material in step S1 is: sulphoaluminate cement: fly ash: accelerator = 1:0.6:0.

05.

3. The high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1 is characterized in that: In step S2, the interface agent is epoxy resin.

4. The high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1 is characterized in that: In step S3, the wear-resistant pad is made of polytetrafluoroethylene.

5. A high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 4, characterized in that: The wear-resistant pad has a thickness of 10 mm, and is provided with anti-skid grooves on the contact surface with the filling body, and the depth of the anti-skid grooves is 1 mm.

6. The high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1 is characterized by: The optical fiber sensor array is arranged along the height direction of the filling body, with one group installed every 0.5m, to monitor the filling body strain and interface stress distribution in real time. The outer layer of the optical fiber sensor array is covered with an explosion-proof sheath made of polyurethane with a pressure resistance level of ≥10MPa.

7. The high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1 is characterized in that: The feedback execution module can dynamically adjust the water-cement ratio of the pumped material according to the sensor data, with a control range of ±0.

1. The crack width at the interface of high- and low-strength materials is analyzed through the optical fiber reflection signal, and the threshold is set to 0.2mm. When the threshold is exceeded, an alarm is triggered and the ratio is automatically corrected.

8. The high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 1 is characterized in that: The mechanical model and parameter design module is based on the secondary fracture characteristics of the roof, establishes a coupling model of the surrounding rock filling body, and calculates the top cutting resistance: Where: α is the coal seam inclination; L is the length of the rock block; q is the deadweight per unit length of the rock block; h is the thickness of the rock block; ΔS C is the amount of subsidence of the roof when the rock block is cut off; Calculation of coal support pressure: Among them, the width of the stress limit equilibrium zone x0 guides the design of the filling body width.

9. A high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 8, characterized in that: ΔS in the model C The allowable value of top plate subsidence is 50 to 80 mm. If it exceeds this value, the width of the filling body needs to be increased.

10. A high-strength filling and low-strength sealing structural filling process for gob-side entry retention according to claim 8, characterized in that: The parameters collected for the geological parameters in step S1 are: coal seam inclination angle α=15°, mining height M=3.2 m and immediate roof thickness h=2.1 m.

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