Three-soft-roadway coupling supporting method integrating anchor frame and grouting

Abstract

The invention discloses a three-soft roadway coupling support method integrating anchor, frame and grouting. Comprising the following steps: S1, mounting a U-shaped steel shed frame; s2, a wood back plate is laid behind the shed frame to lock the shed; s3, a top plate and side anchor cables are constructed; s4, a pressure relief groove is excavated, and a base angle anchor cable is constructed; s5, fast-setting first grout is injected into the anchoring section of the anchor cable drill hole; s6, first-stage pre-tightening force is applied after the first slurry is solidified, so that early-stage rheology of the surrounding rock is inhibited; s7, then high-fluidity second slurry is injected into the non-anchoring section to consolidate the surrounding rock; and S8, applying second-stage pre-tightening force to a final design value (such as 320 kN) after the second slurry is solidified (such as 24 hours). According to the method, the contradiction between the timeliness of high prestress application and the timeliness of slurry solidification in the three-soft roadway is solved, cooperative control over early-stage deformation and later-stage large deformation of the roadway is achieved, and the stability of the roadway is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of coal mine support technology, and more specifically, to a method for coupled support of three soft roadways using an integrated anchor frame and injection system. Background Technology

[0002] Coal is my country's most important basic energy source and will remain so for a considerable period of time. my country's coal deposits are characterized by complex geological conditions, with 90% mined underground. A significant proportion of these are thick or extra-thick coal seams characterized by "three softnesses": a soft roof, soft coal quality, and a soft floor. The compressive strength of these coal seams is... 10 MPa (megapascals), and the compressive strength of the coal seam roof and floor 25 MPa (megapascals).

[0003] Compared to conventional coal seam roadways, the surrounding rock of "three-soft" coal seam roadways is characterized by easy softening upon contact with water, rapid deformation rate, and large deformation amount. Due to the inherent weakness of the surrounding rock, after mining disturbance, the roadway surrounding rock exhibits nonlinear large deformation and significant strong rheological effects. When using traditional support methods (such as single anchor bolt support or U-shaped steel canopy support), the roadway struggles to form a stable load-bearing structure, commonly exhibiting severe floor heave and sidewall spalling, which in turn leads to the bending and subsidence of the composite roof and delamination failure. The deformation of the roof, sidewalls, and floor interacts, creating a vicious cycle that results in difficult roadway support, huge maintenance workload, and high costs in the later stages.

[0004] For example, taking the No. 17 coal seam in Huoshaopu Mine as an example, this coal seam is a typical "three-soft" coal seam. Its roof lithology is thin-layered silty mudstone with well-developed joints, making it extremely prone to collapse; the floor lithology is mudstone, which turns into mud when exposed to water, making it extremely prone to "floor heave". Using existing support technology, it is impossible to effectively control roadway deformation, resulting in slow tunneling speed, significant safety hazards, and a large amount of subsequent maintenance.

[0005] Therefore, there is an urgent need for a new support method that can provide timely, efficient, and long-lasting support for the strong rheological and high deformation rate characteristics of the surrounding rock in "three-soft" roadways, so as to effectively control the large deformation of the surrounding rock, reduce roadway repairs, and ensure safe and efficient mine production. Summary of the Invention

[0006] The main objective of this invention is to overcome the shortcomings of the prior art and provide a three-soft roadway coupling support method integrating anchor frame and injection, thereby solving the technical problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for coupled support of three-soft roadways using integrated anchor frame and injection system includes the following steps: S1: Installing U-shaped steel frames along the roadway outline; S2: Laying wooden backing boards on the side of the U-shaped steel frames away from the roadway excavation face to lock adjacent U-shaped steel frames; S3: Drilling holes for anchor cables in the roadway roof and both sides, and installing anchor cables; S4: Excavating pressure relief grooves at the bottom corners of both sides of the roadway, and constructing bottom corner anchor cables; S5: Injecting a first grout into the end anchoring section of the anchor cable drilled in step S3, wherein the first grout is a super-fine grout. S6: After the first grout solidifies, a first-stage pre-tightening force is applied to the anchor cable, the first-stage pre-tightening force being less than the final design value of the pre-tightening force; S7: After applying the first-stage pre-tightening force, a second grout is injected into the non-anchored section of the anchor cable borehole through the hollow channel of the anchor cable, the second grout being a high-flowability cement-based grout; S8: After the second grout solidifies, a second-stage pre-tightening force is applied to the anchor cable, so that the pre-tightening force of the anchor cable reaches the final design value.

[0009] Further, step S3 includes: installing three roof anchor cables with a specification of Φ21.6×6200mm on the roof of the roadway, with a row spacing of 1400mm; and installing two side anchor cables with a specification of Φ17.8×4200mm on each side of the roadway.

[0010] Further, step S8 includes: applying a preload of 320kN to the top plate anchor cable as the final design value; step S4 includes: the pressure relief groove has a size of 300mm×300mm, and the bottom corner anchor cable is constructed at a 30-degree inclination angle.

[0011] Furthermore, before performing step S1, a temporary support step is also included: S0-1: After the tunnel is excavated, five hollow grouting anchors with a specification of Φ22×2500mm are installed on the top of the tunnel, and the spacing between the hollow grouting anchors is 800mm×800mm; S0-2: The hollow grouting anchors are interlocked using W-shaped steel strips; S0-3: A preload of 100kN is applied to the hollow grouting anchors; S0-4: Delayed grouting is performed through the hollow grouting anchors.

[0012] Furthermore, the first grout reaches the anchoring strength required for the application of the first stage preload within 15 to 30 minutes; the first stage preload is 40% to 60% of the final design value; the second grout is a shrinkage-compensating cement-based grout.

[0013] Furthermore, in step S3, a "1-band 3-hole" T-shaped steel strip is used to interlock the roof anchor cable on the roadway roof; in step S3, a W-shaped steel strip is used to interlock the side anchor cable on both sides of the roadway.

[0014] Furthermore, in step S8, when applying the second stage preload, the preload is kept constant for more than 30 seconds.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This invention integrates "anchoring, scaffolding, and grouting" with a wooden backing plate locking system, forming a coupled load-bearing system of "U-shaped steel scaffolding - wooden backing plate - anchor cable - surrounding rock". The U-shaped steel scaffolding provides initial support, the wooden backing plate achieves "locking" and "buffering" between the scaffolding sections, and the high-prestressed anchor cable (320kN) penetrates deep into the stable rock strata. The three work together to effectively control roof subsidence and sidewall spalling. Then, by excavating pressure relief trenches at the bottom corners of the roadway and constructing bottom corner anchor cables, a channel for stress release of the floor slab is provided, while simultaneously anchoring the floor slab rock strata, fundamentally suppressing the severe floor heave problem that is common and difficult to cure in "three-soft" roadways. Finally, the "time-division pressure-double grouting" process solves the technical contradiction between "three-soft" surrounding rock (rapid deformation rate) and "high prestressing application" (requiring waiting for grout curing). By applying the first-stage pre-tightening force (e.g., 160kN) within 1 hour, the early rapid rheological deformation of the surrounding rock was effectively suppressed; the subsequent secondary grouting and full final tensioning (320kN) achieved the consolidation of the surrounding rock and long-term high pre-stress control, truly realizing "loss prevention and strengthening control". Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of temporary support in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the coupling support technology in an embodiment of the present invention;

[0020] Figure 3 This is an overall construction process diagram of an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] Example 1

[0023] This embodiment uses the ventilation roadway of the 131705 working face of Huoshaopu Mine as the test background to elaborate in detail the complete construction steps of a three-soft roadway coupling support method integrating anchor frame and injection.

[0024] 1. Geological Overview of the Test Roadway: The test roadway is located in the No. 17 coal seam of Huoshaopu Mine. This coal seam is a typical "three-soft" coal seam with extremely complex geological conditions:

[0025] Soft coal seam: The average thickness of coal seam #17 is approximately 4.39 m, with a dip angle of approximately 30°. The coal seam is soft and fractured, with a complex structure and low compressive strength. 10 MPa (megapascals)

[0026] The top plate (soft): The direct top is a 3.8m thick sandy mudstone with broken rock core, well-developed joints, smooth surface, and is extremely prone to collapse.

[0027] The bottom plate (soft): The direct bottom is mudstone, blocky, and when it comes into contact with cement, it is very easy to "bulge".

[0028] Surrounding rock characteristics: After the tunnel is disturbed during excavation, the surrounding rock exhibits nonlinear large deformation and significant strong rheological effects, and it is easily softened when exposed to water.

[0029] 2. Tunnel Excavation and Temporary Support: The tunnel was excavated using a tunneling machine. Due to the poor integrity of the roof of the No. 17 coal seam, roof falls and sidewall spalling were prone to occur during excavation. Therefore, after the tunneling operation was completed, "self-consolidating anchor bolt temporary support technology" was immediately used for temporary support to ensure operational safety and provide conditions for permanent support.

[0030] Step S0-1 (Construction of anchor bolts): As follows Figure 1 As shown, five hollow grouting anchor bolts are drilled and installed along the roadway outline at the top of the roadway behind the excavation face. The anchor bolts are Φ (diameter) 22×2500mm (millimeters) fully threaded anchor bolts. The spacing between the anchor bolts is controlled at 800mm (millimeters) × 800mm (millimeters).

[0031] Step S0-2 (Interlocking): Use W-shaped steel strips to effectively interlock the 5 anchor bolts along the cross-sectional direction of the roadway.

[0032] Step S0-3 (Pre-tightening): Apply a pre-tightening force of 100 kN to the anchor bolt using a pneumatic wrench. The torque requirement is not less than 400 N·m for rock mass and not less than 300 N·m for coal mass.

[0033] Step S0-4 (Grouting): Before the permanent support construction, delayed grouting is performed through the hollow channel of the anchor bolt. The grouting material is ordinary cement slurry, which fills the gaps around the anchor bolt to achieve "self-consolidation" of the anchor bolt.

[0034] 3. Under the protection of temporary support, the integrated anchor frame and injection permanent support is constructed closely following the tunneling face, using the "integrated anchor frame and injection control - wooden backboard lock canopy" coupled support.

[0035] Step S1 (scaffolding): Install U-shaped steel scaffolding (U29 type steel scaffolding is used in this embodiment) along the contour of the tunnel. The spacing between the scaffolding is set to 800mm to 1000mm depending on the surrounding rock conditions.

[0036] Step S2 (locking the canopy): as follows Figure 2 As shown, behind the installed U-shaped steel frame (on the side facing away from the excavation face), a wooden backing board (i.e., a wooden pad) is laid tightly between the U-shaped steel frame and the surrounding rock. The wooden backing board is made of 50mm thick anti-corrosion pine wood. The wooden backing board serves two purposes: first, it acts as a buffer layer to mitigate the impact of surrounding rock deformation on the steel frame; second, it "locks" adjacent U-shaped steel frames together longitudinally, forming a cohesive load-bearing structure.

[0037] Step S3 (Construction Anchor Cable):

[0038] Top slab anchor cables: such as Figure 2 As shown, three anchor cables are installed on the roof of the roadway. The anchor cables are high-strength, low-relaxation steel strands with a diameter of Φ 21.6 × 6200 mm. The roof anchor cables are interlocked using T-shaped steel strips with three holes per strip. The spacing between the three anchor cables is 1400 mm.

[0039] Side anchor cables: Two short anchor cables are installed on each side. The specifications are Φ (diameter) 17.8×4200mm (millimeters). The side anchor cables are interlocked with the W-shaped steel strips of the temporary support, with a spacing of 700×700mm (millimeters).

[0040] Step S4 (Kick Drum Control): As follows Figure 2 As shown, to prevent the mudstone floor from becoming "cement-like" and "floor bulging," pressure relief grooves with a cross-sectional dimension of 300mm × 300mm are excavated at the bottom corners of both sides of the roadway. At the same time, bottom corner anchor cables are installed at a 30-degree inclination angle into the floor rock strata to anchor the floor and limit its deformation.

[0041] 4. Analysis of Key Technical Issues The above steps S1-S4 constitute the foundation of the "anchor lock" of this invention. However, under the strong rheological geological conditions of "three-soft" roadways, the coordination of steps S5 (grouting) and S6 (tensioning) is crucial to the success or failure of the project.

[0042] The prototype of this invention requires "grouting immediately after the anchor cable construction is completed" in order to seal the surrounding rock fissures in a timely manner and prevent the surrounding rock (which is easily softened by water in "three-soft" roadways) from deteriorating due to groundwater. At the same time, the scheme also requires the application of a preload force of up to 320 kN (kilonewtons) to actively suppress the "strong rheology" and "large deformation" of the surrounding rock.

[0043] However, a serious technical contradiction exists here: the requirement for high preload (320kN). Applying high preload requires the anchoring grout (step S5) to reach sufficient anchoring strength. If conventional cement grout (such as P.O42.5 cement mortar) is used, it takes at least 24 hours to reach the anchoring strength required for 320kN (kilonewtons) tension (e.g., >30MPa (megapascals)).

[0044] Strong rheological properties of surrounding rock: "Three soft" surrounding rock has a "fast deformation rate", with the largest deformation occurring within 0-24 hours after excavation.

[0045] If a 24-hour delay is made to allow the grout to cure before applying a preload of 320 kN, significant rheological deformation (floor bulging, spalling) will have already occurred in the surrounding rock during this "support delay period." Applying the high preload will be "too late," missing the optimal opportunity to "stop the damage." Conversely, attempting to apply a high preload immediately after "immediate grouting" will inevitably lead to anchorage failure.

[0046] Technical principle: The rheological properties of "three-soft" surrounding rocks can be simplified and described using the Nishihara model, whose total strain... (Total strain of surrounding rock, varying with time t) is derived from elastic strain. (Elastic strain), viscoelastic strain (Viscoelastic strain) and viscoplastic strain (rheology) (Viscoplastic strain) composition: , ,

[0047] Symbol definition: (Time) refers to time; (Strain of the surrounding rock after tunnel excavation) refers to the stress of the surrounding rock after tunnel excavation; (Elastic modulus) is the elastic modulus; (Viscosity coefficient) is the viscosity coefficient; (Long-term strength or yield limit of the surrounding rock) refers to the long-term strength (yield limit) of the surrounding rock.

[0048] The key to tunnel instability lies in the third factor, namely viscoplastic strain (rheology). In "three-soft" surrounding rocks, Very low (weak rock mass). The viscosity coefficient is very small, resulting in exist The growth rate is extremely fast in the initial stage (i.e., 0-24 hours after tunneling).

[0049] The purpose of support is to provide support resistance. (Support resistance), causing stress in the surrounding rock Rapidly decrease, when hour, Growth has ceased. Conventional processes are in... Within the interval, Minimal (scaffolding resistance only), anchor cable resistance is 0. This is insufficient to prevent... Rapid growth.

[0050] 5. To resolve the above-mentioned technical contradictions, this embodiment refines steps S5 (grouting) and S6 (tensioning) as follows, adopting an improved "time-division pressure-double grouting" grouting and tensioning method.

[0051] Preparation: The anchor cables installed in step S3 (such as Φ (diameter) 21.6×6200mm (millimeters) top plate anchor cables) adopt a dual-channel grouting structure. This includes a central grouting pipe (for the second grout) and a slender external grouting pipe (for the first grout) tied to the outside of the steel strand bundle (the pipe opening (the opening of the external grouting pipe) is located at the end of the anchor hole for injecting the first grout).

[0052] Step S5-1 (Injecting the first slurry):

[0053] After the anchor cable is installed in place, the first grout (first grout, fast setting) is immediately injected into the anchoring section (anchoring section, located at the end of the anchor hole) (e.g., 2.0m (meter) long at the bottom of the hole) through the external grouting pipe.

[0054] Grout selection: The first grout is an ultra-early strength fast-setting grout, such as a two-component polyurethane grout or a modified sulfoaluminate cement grout.

[0055] Setting time: Within 15 to 30 minutes, the shear strength of the anchor body of the grout rapidly reaches more than 25 MPa, which is sufficient to withstand the tension of the first stage.

[0056] Step S6 (Applying the first stage preload):

[0057] After S5 is completed, wait 15-30 minutes until the first grout (anchoring section) reaches the specified strength, then immediately tension the anchor cable and apply the first stage preload. (First stage preload).

[0058] Load selection: The preload is 50% of the final design value (320 kN), i.e., applied... (Qianniu).

[0059] Technical principle: In The 160 kN active preload applied within one hour rapidly provided strong support resistance. According to the aforementioned Nishihara model, this Enough to make (Long-term strength of the surrounding rock), thereby immediately suppressing viscoplastic rheology. The rapid increase in (viscoplastic strain) (i.e., the gradual decrease in the slope of the curve) controlled the early deformation of the surrounding rock.

[0060] Step S7 (Injecting the second slurry):

[0061] After S6 (applying the first stage pre-tightening force) is completed, the second grout (the second grout, which is highly fluid) is immediately injected through the central grouting pipe 20 of the anchor cable.

[0062] Grout selection: The second grout is a high-flowability, shrinkage-compensating cement-based grout (such as P.O42.5 cement, water-cement ratio 0.5:1, with added micro-expansion agent).

[0063] Grouting principle: The grout (slow grout) is injected under low pressure. Its high fluidity allows it to fully fill the voids in the free section (non-anchored section) of the anchor cable and penetrate into the broken surrounding rock around the anchor hole through the cracks, while filling the voids between the wooden backing and the surrounding rock.

[0064] Function: To achieve "full-length dense grouting" of the surrounding rock (i.e., "grouting" in "anchor-frame integrated grouting"), consolidate the fractured surrounding rock, isolate moisture (prevent "softening upon contact with water"), and significantly improve the overall strength of the surrounding rock. (Long-term strength and elastic modulus of the surrounding rock) (Elastic modulus).

[0065] Step S8 (Applying the second stage preload):

[0066] After S7 is completed, wait for the second slurry to fully solidify (e.g., after 24 hours).

[0067] Load application: The anchor cable is tensioned a second time using a tensioning device, increasing the preload from 160 kN (kilonewtons) (first stage). Increased to 320 kN (kilonewtons) (final design value) (Final design value preload)

[0068] Operating requirements: When the tensioner pressure reaches 40 MPa (megapascals) (corresponding to 320 kN (kilonewtons)), the pressure must be maintained for more than 30 seconds to ensure effective transmission of tension force.

[0069] Technical principle: At this point, the surrounding rock has been consolidated by the second grout ( (Improved), the entire support system has formed a high-strength "anchor-injection-rock" composite. A high prestress of 320kN (kilonewtons) is applied to this composite, giving it a strong ability to resist later mining stress or long-term rheological changes, achieving the ultimate goal of "loss prevention and enhanced control".

[0070] 6. Monitoring and Feedback: Monitoring stations are set up in the roadway to monitor the anchor cable stress and roof delamination in real time, and to analyze the effectiveness of the support parameters of this invention in soft, slippery roadways. The support parameters for the next cycle are dynamically adjusted based on the monitoring data (e.g., if early rheology is still rapid, the preload in the first stage can be appropriately increased). (The value is up to 60% of the final value).

[0071] 7. Summary of the Implementation Example This implementation example, based on the "anchor frame injection integrated control - wooden backboard lock" technology, innovatively introduces the "time-division pressure-double slurry" construction method, which solves the technical contradiction between the "strong rheology" (fast deformation rate) requirement for "timely support" and the "high prestress" (320kN) requirement for "delayed application" in "three soft" roadways.

[0072] conventional process (Conventional support resistance curve) The support resistance is 0 within 24 hours, leading to deformation of the surrounding rock. The total deformation curve of conventional processes continues to increase rapidly. However, this invention... (The support resistance curve of this invention) is applied within 1 hour. and apply after 24 hours Its support resistance is always higher than the resistance required by the surrounding rock, effectively reducing the total deformation. (The total deformation curve of this invention) is controlled within (e.g.) ) level.

[0073] The method of this invention was applied to the construction of ventilation roadway 131705, resulting in a 30% increase in tunneling efficiency and a 30% reduction in roadway repair time, achieving significant technical and economic benefits.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-soft roadway coupling support method integrated with anchor frame injection, characterized in that, The method comprises the following steps: S1: installing a U-shaped steel shed along the roadway profile; S2: laying a wood back plate on the side of the U-shaped steel shed away from the roadway heading face to achieve locking of adjacent U-shaped steel sheds; S3: drilling anchor cable holes in the roadway roof and two sides and installing anchor cables; S4: excavating a pressure relief groove at the bottom corner of the roadway two sides and constructing a bottom corner anchor cable; S5: injecting a first slurry into the end anchoring segment of the anchor cable hole in step S3, the first slurry being a super-early-strength quick-setting slurry; S6: after the first slurry solidifies, applying a first-stage pre-tightening force to the anchor cable, the first-stage pre-tightening force being less than the final design value of the pre-tightening force; S7: after the first-stage pre-tightening force is applied, injecting a second slurry into the non-anchoring segment of the anchor cable hole through the hollow passage of the anchor cable, the second slurry being a high-fluidity cement-based slurry; S8: after the second slurry solidifies, applying a second-stage pre-tightening force to the anchor cable so that the pre-tightening force of the anchor cable reaches the final design value.

2. The method of claim 1, wherein, The step S3 comprises: installing three roof anchor cables with a specification of Φ21.6×6200 mm on the roadway roof, the row distance of the roof anchor cables being 1400 mm; and installing two side anchor cables with a specification of Φ17.8×4200 mm on the roadway two sides.

3. The method according to claim 1 or 2, characterized in that, The step S8 comprises: applying a pre-tightening force of 320 kN to the roof anchor cable as the final design value; and the step S4 comprises: the size of the pressure relief groove being 300 mm×300 mm, and the bottom corner anchor cable being constructed at an inclination angle of 30 degrees.

4. The method of claim 1, wherein, Before step S1 is performed, a temporary support step is further included: S0-1: after the roadway is excavated, five hollow grouting anchor rods with a specification of Φ22×2500 mm are constructed on the roadway roof, the interval row distance of the hollow grouting anchor rods being 800 mm×800 mm; S0-2: a W-shaped steel belt is used to interlock the hollow grouting anchor rods; S0-3: a pre-tightening force of 100 kN is applied to the hollow grouting anchor rods; and S0-4: hysteresis grouting is performed through the hollow grouting anchor rods.

5. The method of claim 1, wherein, The first slurry reaches the anchoring strength required for the first-stage pre-tightening force application within 15 to 30 minutes; the first-stage pre-tightening force is 40% to 60% of the final design value; and the second slurry is a shrinkage-compensating cement-based grouting material.

6. The method of claim 1, wherein, In step S3, a "1 belt 3 hole" T-shaped steel belt is used to interlock the roof anchor cables on the roadway roof; and in step S3, a W-shaped steel belt is used to interlock the side anchor cables on the roadway two sides.

7. The method of claim 1, wherein, In step S8, when the second-stage pre-tightening force is applied, the pre-tightening force is kept constant for more than 30 seconds.

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