A high-strength filling and low-strength sealing structural filling process for gob-side entry retaining

Abstract

This invention discloses a high-strength filling and low-strength sealing structural filling process for gob-side roadway retention, specifically including the following steps: S1, Construction preparation: geological parameter acquisition, pre-embedding fiber optic sensor arrays in the roadway side area, connecting to a mine explosion-proof control box, and then pre-mixing dry materials according to the high-strength filling material ratio; S2, High-strength filling; S3, Low-strength sealing; S4, Dynamic control and maintenance. This invention relates to the field of gob-side roadway support technology in coal mines. This high-strength filling and low-strength sealing structural filling process ensures structural stability during periods of high mine pressure with high-strength filling, while the low-strength sealing layer improves airtightness and extends the roadway's service life during stable periods. Through fiber optic sensing and mechanical models, material properties are adjusted in real time to avoid over-support or insufficient sealing, reduce the need for additional sealing layer construction, lower material and labor costs, effectively control the risk of secondary roof fracture, and reduce gas leakage and surrounding rock instability accidents.

Description

Technical Field

[0001] This invention relates to the field of underground gob-side roadway support technology in coal mines, specifically a high-strength filling and low-strength sealing structural filling process for gob-side roadway support. Background Technology

[0002] Roadway retention along the goaf is a crucial technique for efficient coal mining. Its core lies in controlling roof strata movement and maintaining roadway stability through roadway backfill. Traditional backfilling techniques often use single-strength materials, which are ill-suited to adapting to dynamic changes in mine pressure during mining, leading to the following problems:

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

[0004] 2. Stable stage: The high-strength material is too rigid and cannot adapt to the stress release of the surrounding rock, resulting in poor sealing and an increased risk of gas leakage in the goaf.

[0005] 3. Material waste: A single strength design cannot meet both support and sealing requirements, requiring an additional sealing layer and increasing costs.

[0006] While existing technologies (such as high-water-content material filling) can achieve rapid solidification, they lack dynamic performance regulation mechanisms and cannot achieve phased performance optimization. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a structural filling process for high-strength filling and low-strength sealing along the goaf, solving the problems of traditional filling processes being unable to effectively cope with the dynamic changes in mine pressure during mining, making it difficult to balance support and sealing performance, single-strength filling materials being prone to instability during high mine pressure stages, and being prone to insufficient sealing due to excessive rigidity during stable stages, lacking real-time monitoring methods, and being unable to ensure the coordinated work of high and low strength material interfaces.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a high-strength filling and low-strength sealing structural filling process for gob-side roadway retention, specifically comprising the following steps:

[0009] S1. Construction preparation: Geological parameters are collected, fiber optic sensor arrays are pre-buried in the area next to the tunnel and connected to the mine explosion-proof control box, and then dry materials are pre-mixed according to the high-strength filling material ratio, and 12% bentonite is added to the sealing material.

[0010] S2. High-strength filling: A dual-liquid grouting pump is used to inject high-water material with a water-cement ratio of 1.4:1 into the roadway side. The width of the filling body is set to 3.0m. The strain data is fed back in real time through fiber optic sensors to ensure that the compressive strength after 28 days is ≥12 MPa, thereby forming a high-strength filling body. Then, an interface agent is sprayed on the surface of the high-strength filling body to enhance the adhesion with the sealing layer.

[0011] S3. Low-strength sealing: After the mine pressure stabilizes, adjust the water-cement ratio to 1.5:1, pump low-strength material to cover the high-strength filling body with a thickness of 0.5m, use fiber optic reflection signal to analyze interface cracks, if the crack width is >0.2 mm, automatically increase the bentonite content to 15%, support the sealing layer with wear-resistant pads, and allow it to generate 5%-8% compression with the deformation of the surrounding rock.

[0012] S4. Dynamic Control and Maintenance: The mine control box generates a stress-strain curve every 24 hours. Abnormal data is manually reviewed. 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.

[0013] Preferably, the specific ratio of the high-strength filling material in step S1 is: sulfoaluminate cement: fly ash: accelerator = 1:0.6:0.05.

[0014] Preferably, the interface agent in step S2 is epoxy resin.

[0015] Preferably, the wear-resistant pad in step S3 is made of polytetrafluoroethylene.

[0016] Preferably, the wear-resistant pad has a thickness of 10mm, and the contact surface with the filling body is provided with anti-slip texture, and the depth of the anti-slip texture is 1mm.

[0017] Preferably, the fiber optic sensor array is arranged along the height direction of the filling body, with one set installed at every 0.5m interval, to monitor the strain and interface stress distribution of the filling body in real time. The outer layer of the fiber optic sensor array is covered with an explosion-proof protective sleeve made of polyurethane with a pressure resistance rating of ≥10 MPa.

[0018] Preferably, the feedback execution module can dynamically adjust the water-cement ratio of the pumped material based on sensor data, with a control range of ±0.1. It analyzes the crack width at the interface between high and low strength materials through fiber optic reflection signals, with a threshold set at 0.2 mm. When the threshold is exceeded, an alarm is triggered and the mix ratio is automatically corrected.

[0019] Preferably, the mechanical model and parameter design module is based on the secondary fracture characteristics of the roof, establishing a coupled model of the surrounding rock infill body, and calculating the roof cutting resistance:

[0020] ;

[0021] In the formula: The dip angle of the coal seam; The length of the rock block; The weight per unit length of the rock block. The thickness of the rock block, This represents the amount of subsidence of the top plate when the rock block is cut off;

[0022] Calculation of coal seam support pressure: ;

[0023] Among them, the width of the stress limit equilibrium zone This guides the design of the filling body width.

[0024] Preferably, in the model The allowable settlement of the roof slab is 50~80 mm. If it exceeds this, the width of the filling body needs to be increased.

[0025] Preferably, the geological parameters collected in step S1 are: measuring the coal seam dip angle. =15°, mining height M=3.2m and immediate roof thickness h=2.1m.

[0026] This invention provides a high-strength filling and low-strength sealing structural filling process for roadway retention along the goaf. Compared with the prior art, it has the following advantages:

[0027] (1) The high-strength filling and low-strength sealing structural filling process of the roadway along the goaf ensures structural stability during the strong mine pressure stage, and the low-strength sealing layer improves the airtightness and extends the service life of the roadway during the stable stage. The material properties are adjusted in real time through fiber optic sensing and mechanical model to avoid excessive support or insufficient sealing.

[0028] (2) The high-strength filling and low-strength sealing structural filling process of the goaf-retaining roadway reduces the construction of additional sealing layers, reduces material and labor costs, effectively controls the risk of secondary fracture of the roof, and reduces gas leakage and surrounding rock instability accidents. Attached Figure Description

[0029] Figure 1 This is a mechanical model diagram of the goaf retention method of the present invention;

[0030] Figure 2 This invention covers the entire process from high-strength filling construction and low-strength sealing layer laying to real-time monitoring and feedback. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figure 1-2The present invention provides two technical solutions: a high-strength filling and low-strength sealing structural filling process for roadway retention along the goaf, specifically including the following embodiments:

[0033] Example 1: Specifically includes the following steps:

[0034] S1. Construction preparation: Geological parameters are collected, fiber optic sensor arrays are pre-buried in the area next to the tunnel and connected to the mine explosion-proof control box, and then dry materials are pre-mixed according to the high-strength filling material ratio, and 12% bentonite is added to the sealing material.

[0035] S2. High-strength filling: A dual-liquid grouting pump is used to inject high-water material with a water-cement ratio of 1.4:1 into the roadway side. The width of the filling body is set to 3.0m. The strain data is fed back in real time through fiber optic sensors to ensure that the compressive strength after 28 days is ≥12 MPa, thereby forming a high-strength filling body. Then, an interface agent is sprayed on the surface of the high-strength filling body to enhance the adhesion with the sealing layer.

[0036] 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 material to cover the high-strength filling body with a thickness of 0.5m, use fiber optic reflection signal to analyze interface cracks, if the crack width is >0.2 mm, automatically increase the bentonite content to 15%, support the sealing layer with wear-resistant pads, and allow it to generate 5%-8% compression with the deformation of the surrounding rock;

[0037] S4. Dynamic Control and Maintenance: The mine control box generates a stress-strain curve every 24 hours. Abnormal data is manually reviewed. 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.

[0038] In this embodiment of the invention, the specific ratio of the high-strength filling material in step S1 is: sulfoaluminate cement: fly ash: accelerator = 1:0.6:0.05.

[0039] In this embodiment of the invention, the interface agent in step S2 is epoxy resin.

[0040] In this embodiment of the invention, the wear-resistant pad in step S3 is made of polytetrafluoroethylene.

[0041] In this embodiment of the invention, the wear-resistant pad is 10mm thick, and the contact surface with the filling body is provided with anti-slip texture, and the depth of the anti-slip texture is 1mm.

[0042] Example 2: The technical solution that differs from Example 1 is that the fiber optic sensor array is arranged along the height direction of the filling body, with one set installed at every 0.5m interval, to monitor the strain and interface stress distribution of the filling body in real time. The outer layer of the fiber optic sensor array is covered with an explosion-proof protective sleeve, the sleeve material is polyurethane, and the pressure resistance rating is ≥10 MPa.

[0043] In this embodiment of the invention, the feedback execution module can dynamically adjust the water-cement ratio of the pumped material based on sensor data, with a control range of ±0.1. It analyzes the crack width at the interface between high and low strength materials through optical fiber reflection signals, with a threshold set at 0.2 mm. When the threshold is exceeded, an alarm is triggered and the mix ratio is automatically corrected.

[0044] In this embodiment of the invention, the mechanical model and parameter design module establishes a coupled model of the surrounding rock filling body based on the secondary fracture characteristics of the roof, and calculates the roof cutting resistance: ;

[0045] In the formula: The dip angle of the coal seam; The length of the rock block; The weight per unit length of the rock block. The thickness of the rock block, This represents the amount of subsidence of the top plate when the rock block is cut off;

[0046] Calculation of coal seam support pressure: ;

[0047]

[0048] In the formula:

[0049] , —The cohesion and internal friction angle at the interface between the coal seam and the roof and floor strata;

[0050] — Coal seam dip angle;

[0051] —The support resistance of the support frame to the coal face;

[0052] — Lateral pressure coefficient;

[0053] —High-level mining;

[0054] —Mining depth;

[0055] —Average unit weight of the overlying strata;

[0056] —Stress concentration factor.

[0057] Calculation of roadway side support resistance: using the balance method , Mechanical equations were established for each of the two rock blocks.

[0058] Rock block, perpendicular to the dip angle direction, ,have to:

[0059] Parallel to the angle of inclination direction, ,have to:

[0060] ,have to:

[0061]

[0062] rock blocks ,have to:

[0063]

[0064]

[0065] In the formula:

[0066] — Coal seam dip angle;

[0067] —Wide width of the alleyway;

[0068] —Width of the support structure beside the alley;

[0069] —Thickness of the basic top rock layer;

[0070] —The shear resistance of the roadside support structure;

[0071] —The ultimate bending moment of the basic top rock stratum;

[0072] — The residual bending moment at the top of the end base;

[0073] —The self-weight per unit length of the main top and the weak rock layers above it;

[0074] —Directly weighing the unit length of its own weight;

[0075] —Before the basic top span fell The amount of sinking at the end,

[0076] The formula is:

[0077]

[0078] — The length of the rock block is calculated using the following formula:

[0079]

[0080] In the formula:

[0081] —Basic top pressure step distance;

[0082] —Working face length.

[0083] The specific geomechanical parameter values ​​are as follows:

[0084] The 090515 working face is a fully mechanized top-coal caving longwall face with an average coal seam thickness of 4.1m, a mining height of 2.8m, a top-coal caving height of 1.3m, a working face length of 204m, a periodic pressure step distance of 15m, a maximum roadway depth of 454m, an immediate roof thickness of 5.83m, an overlying roof thickness of 7.18m, and an overlying stratum unit weight of 24kN / m³. 3 The stress concentration factor is 2.0, the maximum tensile strength of the basic roof stratum is 2.4 MPa, the lateral pressure coefficient is 0.5, the coal seam cohesion is 1.7 MPa, the internal friction angle is 53.67º, the sidewalls are supported by twisted anchor bolts with a support resistance of 0.06 MPa, and the coal seam dip angle is considered to be an average of 4°. Substituting the above parameters into the formula, the shear resistance of the 090515 track roadway filling body is 19.19 MN / m. During on-site construction, the overall strength of the filling body is considered to be 10 MPa, and the theoretical value of the required filling body width is 1.92 m.

[0085] In this embodiment of the invention, the model The allowable settlement of the roof slab is 50~80 mm. If it exceeds this, the width of the filling body needs to be increased.

[0086] In this embodiment of the invention, the geological parameters collected in step S1 are: measuring the coal seam dip angle. =15°, mining height M=3.2m and immediate roof thickness h=2.1m.

[0087] In summary, the high-strength backfill body in the high-pressure stage ensures structural stability, while the low-strength sealing layer in the stable stage improves airtightness and extends the service life of the roadway. By adjusting the material properties in real time through fiber optic sensing and mechanical models, the invention avoids over-support or insufficient sealing, reduces the need for additional sealing layer construction, lowers material and labor costs, effectively controls the risk of secondary roof fracture, and reduces gas leakage and surrounding rock instability accidents.

[0088] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0089] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength filling and low-strength sealing structural filling process for roadway retention along the goaf, characterized in that: Specifically, the following steps are included: S1. Construction preparation: Geological parameters are collected, fiber optic sensor arrays are pre-buried in the area next to the tunnel and connected to the mine explosion-proof control box, and then dry materials are pre-mixed according to the high-strength filling material ratio, and 12% bentonite is added to the sealing material. S2. High-strength filling: A dual-liquid grouting pump is used to inject high-water material with a water-cement ratio of 1.4:1 into the roadway side. The width of the filling body is set to 3.0m. The strain data is fed back in real time through fiber optic sensors to ensure that the compressive strength after 28 days is ≥12 MPa, thereby forming a high-strength filling body. Then, an interface agent is sprayed on the surface of the high-strength filling body to enhance the adhesion 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 material to cover the high-strength filling body with a thickness of 0.5m, use fiber optic reflection signal to analyze interface cracks, if the crack width is >0.2 mm, automatically increase the bentonite content to 15%, support the sealing layer with wear-resistant pads, and allow it to generate 5%-8% compression with the deformation of the surrounding rock. S4. Dynamic Control and Maintenance: The mine control box generates a stress-strain curve every 24 hours. Abnormal data is manually reviewed. 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. The high-strength filling and low-strength sealing structural filling process for roadway retention according to claim 1, characterized in that: The specific ratio of the high-strength filling material in step S1 is: sulfoaluminate cement: fly ash: accelerator = 1:0.6:0.

05.

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

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

5. The high-strength filling and low-strength sealing structural filling process for gob-side retention according to claim 4, characterized in that: The wear-resistant pad is 10mm thick, and the contact surface with the filling body is provided with anti-slip texture, and the depth of the anti-slip texture is 1mm.

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

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

1. It analyzes the crack width at the interface between high and low strength materials through fiber optic reflection signals, with a threshold set at 0.2 mm. When the threshold is exceeded, an alarm is triggered and the mix ratio is automatically corrected.

8. The high-strength filling and low-strength sealing structural filling process for roadway retention according to claim 1, characterized in that: The geological parameters collected in step S1 are: measuring the coal seam dip angle. =15°, mining height M=3.2m and immediate roof thickness h=2.1m.

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