A graded grouting energy absorption and anti-scour method based on tunnel damage degree

Abstract

The present invention discloses a graded grouting energy absorption and anti-impact method based on the degree of tunnel damage, which relates to the technical field of deep dynamic load tunnel grouting technology. Its technical points include the following steps: Step 1: Drilling construction is carried out before grouting reinforcement operation, and the boreholes are arranged on both sides and the top plate of the tunnel surrounding rock. The boreholes are drilled perpendicular to the inner wall of the tunnel surrounding rock along the inclination of the tunnel, and the boreholes are equidistantly distributed; Step 2: The sonic test probe is set in position close to the inner wall of the borehole, aligned and arranged in parallel, and the surrounding rock wave velocity measurement operation is carried out. The measurement operation is carried out in sequence from shallow to deep, with a measurement interval of 30.0 cm, and the wave velocity value of each test point is recorded; The technical effect is to integrate the segmented and layered anti-impact structure design concept through the coordinated segmented grouting measures and technologies of flexible and rigid grouting materials, and construct the anti-impact layer system structure from deep to shallow, which greatly exerts the impact resistance and energy dissipation capacity of the tunnel surrounding rock itself.

Description

Technical Field

[0001] The invention relates to the technical field of deep dynamically loaded tunnel grouting technology, in particular to a graded grouting energy absorption and anti-impact method based on tunnel damage degree. Background Art

[0002] As an important energy driver for the country's modern economic development, the safe mining of coal resources is a crucial guarantee for the healthy and green development of the national economy. With the increasing depletion of shallow coal resources, "moving deeper" is the strategic direction for coal resource mining to promote the sustainable development of the national economy and ensure national energy security. With the increasing depth of coal resource mining, the stress environment of deep tunnels, the mechanical properties of the tunnel surrounding rock, the spatial migration pattern of the overburden, and the manifestation mechanism of coal and rock dynamic disasters are becoming increasingly complex. The impact dynamic loads generated by mining-induced mine tremors seriously affect the stability of the tunnels, leading to continuous damage and deformation of the tunnels, and even causing the occurrence of nonlinear dynamic disasters such as rock bursts, posing a serious threat to the safety of miners and the normal use of mining equipment. Therefore, considering the stress characteristics of deep tunnels, it is urgent to study and propose effective support measures and methods for deep tunnels under dynamic loads.

[0003] After tunnel excavation, under the dual effects of excavation unloading effect and mining stress, the cracks in the shallow surrounding rock of the tunnel are fully developed and the density of the crack network is high, which makes the shallow surrounding rock of the tunnel prone to bulging deformation, loosening, spalling and cracking, and even slagging and delamination, destroying the integrity and stability of the tunnel surrounding rock. As the depth of the tunnel surrounding rock gradually increases, the degree of crack development and the density of secondary cracks gradually decrease, and the stability of the tunnel surrounding rock gradually increases until it enters the original rock stress zone and no longer changes. Grouting technology can change the physical and mechanical properties of the tunnel surrounding rock through the bonding and solidification of slurry, enhance the cohesion between surrounding rock blocks, reduce porosity, and improve the bearing capacity and integrity of the tunnel surrounding rock. It is a convenient, economical, fast and technically mature tunnel support measure that has been unanimously recognized and applied by many tunnel support experts and scholars. Existing grouting materials are mostly silicate cement, which exhibits a certain degree of rigidity after solidification but lacks energy absorption and shock absorption properties or flexible support characteristics. This makes it difficult to exert toughness under impact loads and mitigate the damaging effects of dynamic loads on roadways. Therefore, energy-absorbing grouts, which absorb energy through deformation or structural failure of the grouting material itself, have emerged. These grouting materials are primarily composed of epoxy resin, polyurethane, or expanded perlite. However, compared to the energy carried by impact loads induced by spatial motion in the overburden, the energy absorption capacity of energy-absorbing grouts within a limited porous fracture volume is significantly insufficient. The effectiveness of relying on energy-absorbing grouts to fully absorb energy is controversial and lacks verification. Therefore, utilizing surrounding rock grouting modification technology to fully utilize the synergistic load-bearing capacity and energy absorption effects of the surrounding rock and grouting is an effective and innovative research direction, thereby reducing roadway dynamic load damage and avoiding deformation and dynamic instability. At the same time, current roadway support grouting materials primarily use one of the aforementioned materials, which violates the principle of synergistic rigidity and flexibility, resulting in significant limitations and deficiencies in support effectiveness. Furthermore, there's no unified standard for grouting depth, relying primarily on empirical judgment. There's a lack of scientific grouting depth determination and judgment. Excessive grouting depth can lead to economic losses; conversely, insufficient support strength can easily fail to meet safety standards. With the increasing degree of mechanization and the precision of data acquisition equipment, the use of acoustic wave detection and determination of surrounding rock velocity values ​​can effectively identify the degree of crack development and initial damage zones in roadway surrounding rocks, providing a prerequisite for the implementation of scientific and effective grouting measures. Based on acoustic wave detection technology, a method for energy-absorbing grouting support and anti-blowout measures in deep roadways that considers initial damage is proposed. This method aims to accurately determine and delineate the distribution of cracks and damage zones in the roadway surrounding rock through acoustic wave detection technology, thereby guiding the drilling and grouting depths. By utilizing the drilled hole pore structure and segmented grouting with rigid and flexible slurries, the method maximizes the energy absorption function of the deep surrounding rock in the roadway and enhances the bearing capacity and impact resistance of the shallow surrounding rock. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention provides a graded grouting energy absorption and impact prevention method based on the degree of roadway damage. This method leverages the importance and necessity of segmented grouting, combining rigid grouting with flexible grouting materials, to fully utilize and enhance the energy absorption and bearing capacity of the roadway surrounding rock. This method not only provides scientific decision-making support for roadway grouting support but also effectively reduces the degree of damage caused by roadway deformation and impact, providing greater safety assurance for coal mine production. It has broad application prospects and socioeconomic value.

[0005] To achieve the above object, the present invention provides the following technical solution: a graded grouting energy absorption and anti-impact method based on the degree of tunnel damage, comprising the following steps:

[0006] Step 1: Drill holes before grouting reinforcement. Arrange the holes on both sides and top of the tunnel surrounding rock. Drill holes perpendicular to the inner wall of the tunnel surrounding rock along the tunnel inclination. The holes are evenly spaced.

[0007] Step 2: Position the acoustic wave test probe close to the inner wall of the borehole, align and arrange them parallel to each other, and start measuring the wave velocity of the surrounding rock. Carry out the measurement from shallow to deep, with a measurement interval of 30.0 cm, and record the wave velocity value at each test point;

[0008] Step 3: Make a secondary correction to the borehole depth based on the wave velocity evolution trend, and divide the borehole into zones from shallow to deep, namely, the crushing zone, the plastic zone, and the in-situ rock stress zone;

[0009] Step 4: Analyze the wave velocity in the crushed area and the original rock stress area, and record the minimum wave velocity value V min and maximum wave velocity V max , calculate the surrounding rock damage degree, and divide the damaged area into high damage area, transition damage area and original rock stress area according to the damage degree result;

[0010] Step 5: Seal the hole at 20.0 cm in the transition damage zone and the original rock stress section, and inject energy-absorbing slurry into this discontinuous interval;

[0011] Step 6: After the energy absorption grouting is completed, the borehole opening is sealed and nano-based grouting is performed in the highly damaged area;

[0012] Step 7: Repeat steps 2 to 6 for the remaining holes.

[0013] Preferably, the surrounding rock damage degree calculation formula is: ;

[0014] Where: V min is the minimum wave velocity value in the highly damaged area; V max is the maximum wave velocity value in the original rock stress zone;V d For depth d The wave velocity value at ; D d For depth d The degree of damage.

[0015] Preferably, the energy-absorbing slurry in the transitional damaged section in step five is a resin slurry energy-absorbing material, which has the characteristics of low viscosity and high ductility and can form a flexible support reinforcement layer.

[0016] Preferably, the nano-based material in step six is ​​nano-based silica slurry, which is used to fill the tiny pores in the shallow surrounding rock of the tunnel, improve the density and cohesion between blocks, and improve stability and impact resistance.

[0017] Preferably, the length of the original rock stress zone is ≥2m.

[0018] Compared with the existing technology, the present invention provides a graded grouting energy absorption and anti-impact method based on the degree of tunnel damage, which has the following beneficial effects: through the coordinated segmented grouting measures and technologies of flexible and rigid grouting materials, it integrates the design concept of segmented and layered impact-resistant structure, and constructs the anti-impact layer system structure of "drilling structure dynamic load buffer energy absorption layer - energy-absorbing slurry buffer energy absorption layer - shallow high-strength slurry reinforcement layer" from deep to shallow, which greatly exerts the impact resistance and energy dissipation capacity of the tunnel surrounding rock itself, and greatly improves the energy dissipation coefficient in the dynamic load transmission process and the stability and strength of the shallow tunnel surrounding rock through energy absorption and wave dissipation means;

[0019] Through the use of acoustic wave measurement technology, the initial damage of the tunnel surrounding rock is taken into account, the effective scientific layout depth of the grouting drilling is determined, and the human error based on experience is overcome.

[0020] By extending the grouting depth, a slurry solidification anchoring structure is formed between the unstable layer and the stable layer. Since the slurry has a certain shear and tensile resistance after solidification, it can form an anchor reinforcement structure, strengthen the bonding strength between layers, and avoid the occurrence of deformation disasters such as delamination, spalling and overall bulging. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the arrangement of grouting holes for surrounding rock grouting in the roadway;

[0022] Figure 2 This is a schematic diagram of the layout of the acoustic wave test points for boreholes 1 and 2;

[0023] Figure 3 This is the wave velocity distribution curve of borehole measuring points No. 1 and No. 2;

[0024] Figure 4 The damage curves of No. 1 and No. 2 boreholes at different depths;

[0025] Figure 5 The maximum depth curve of the damaged area at different drilling heights;

[0026] Figure 6 The maximum depth curve of transition damage zone in different boreholes;

[0027] Figure 7 is the distribution curve of critical depth of damage area;

[0028] Figure 8 This is a schematic diagram of segmented grouting of surrounding rock in the tunnel;

[0029] Figure 9 Schematic diagram of the layered impact-resistant structure of the tunnel surrounding rock after segmented grouting. DETAILED DESCRIPTION

[0030] In the present invention, unless otherwise specified, directions such as "up" and "down" are generally used with respect to the directions shown in the drawings, or with respect to the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "left" and "right" are generally used with respect to the left and right shown in the drawings; "inside" and "outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directions are not used to limit the present invention.

[0031] See also Figures 1-9 The present invention provides a technical solution for a graded grouting energy absorption and anti-impact method based on the degree of tunnel damage, which includes the following steps:

[0032] Step 1: Drill holes before grouting reinforcement. Arrange the holes on both sides and top of the tunnel surrounding rock. Drill holes perpendicular to the inner wall of the tunnel surrounding rock along the tunnel inclination. The holes are evenly spaced, such as Figure 1 As shown, the specific number of drill holes can be adaptively adjusted without specific restrictions. The drill hole diameter is 10.0 cm and the drill hole depth is 10.0 m. The drill hole spacing and depth will be modified based on the grouting effect. After the drilling operation is completed, the coal powder and rock chips in the drill hole will be cleared.

[0033] Step 2: Place the acoustic wave test probe close to the inner wall of the borehole, align and arrange it in parallel, and carry out the surrounding rock wave velocity measurement operation, and carry out the measurement operation from shallow to deep, such as Figure 2 As shown (serial numbers ①-⑥ indicate sequential measurements and are not used to limit the number of measurement points), the measurement interval is 30.0 cm, and the wave velocity value of each test point is recorded;

[0034] Further: Take the wave velocity measurement between borehole 1 and borehole 2 as an example, Figure 2As shown in the figure, the acoustic wave measurement points are set in sequence from shallow to deep with a spacing of 30.0 cm along the grouting borehole. The transmitter and receiver of the acoustic wave measurement are respectively placed at the corresponding measurement points in borehole No. 1 and borehole No. 2. The probe is close to the borehole surface to complete one acoustic wave measurement. Then, the wave velocity measurement work of the remaining measurement points is completed in sequence from shallow to deep, and the wave velocity measured at each measurement point is recorded and a curve is drawn, as shown in the figure. Figure 3 As shown (number the test points in sequence and draw the wave velocity change curve). When the wave velocity measurement shows a high value and stabilizes, the wave measurement work surface can be ended;

[0035] Step 3: Make a secondary correction to the borehole depth based on the wave velocity evolution trend, and divide the borehole into zones from shallow to deep, namely, the crushing zone, the plastic zone, and the in-situ rock stress zone;

[0036] Supplementary explanation: Due to the significant excavation damage effect on the surrounding rock of deep tunnels, the surrounding rock can be divided into a crushed zone, a plastic zone, and an in-situ stress zone, from shallow to deep. This results in a three-stage evolutionary trend in wave velocity measurements: "low value fluctuation, gradual increase, and high value stable fluctuation," which spatially corresponds to the damaged and fractured zones. If the wave velocity measurement is in the "gradual increase" evolutionary stage, drilling should continue until the "high value stable fluctuation" stage is reached. The distance in the "high value stable fluctuation" stage must be maintained at least 2.0m. A secondary correction to the drilling depth is made based on this wave velocity distribution pattern.

[0037] Step 4: Analyze the wave velocity in the crushed area and the original rock stress area, and record the minimum wave velocity value V min and maximum wave velocity V max , calculate the surrounding rock damage degree, and divide the damaged area into high damage area, transition damage area and original rock stress area according to the damage degree result;

[0038] It should be noted that the wave velocity range in the highly damaged area is 0-2.0 km / s; the wave velocity range in the transitional damage area is 2.0-4.0 km / s; and the wave velocity in the original rock stress area is higher than 4.0 km / s. The above wave velocity ranges need to be determined according to specific construction conditions and are not the only limiting conditions.

[0039] Step 5: Seal the hole at 20.0 cm in the transition damage zone and the original rock stress section, and inject energy-absorbing slurry in this discontinuous interval. When the grouting pressure suddenly increases and the flow rate decreases significantly, stop grouting. Figure 8 As shown in the figure, the No. 1 and No. 2 grout plugs are used to seal the transition damage zone and the original rock stress zone;

[0040] Step 6: After the energy-absorbing grouting is completed, the borehole mouth is sealed, and nano-based grouting is performed in the highly damaged area. When the grouting pressure suddenly increases and the flow rate drops significantly, the grouting is stopped. After the grouting is completed, the borehole mouth is sealed, and the No. 2 and No. 3 grout stoppers are used to seal the transitional damage area and the highly damaged area.

[0041] Step 7: Repeat steps 2 to 6 for the remaining holes;

[0042] Repeat steps 2 to 6 in the remaining grouting holes to perform segmented grouting. The results after grouting are as follows: Figure 9 As shown in the figure, the tunnel surrounding rock structure, from shallow to deep, can be divided into: a nano-scale high-strength grouting reinforcement layer, an energy-absorbing slurry layer, and a dynamic load buffer layer of a drilled structure. The advantage of this layered, combined impact-resistant structure is that it fully utilizes the energy absorption and impact resistance properties of the tunnel surrounding rock, significantly absorbing the energy of dynamic shock waves and increasing the bearing capacity and impact resistance of the tunnel surrounding rock.

[0043] At the same time, after the slurry solidifies, a 20.0 cm column of slurry can anchor the highly damaged area to the transitional damaged area, and the transitional damaged area to the original rock stress area, improving the connection strength between the layers and preventing the occurrence of delamination phenomena that cause large deformation and impact damage to the roadway. Specifically, when far-field dynamic loads are generated, the dynamic load stress carries a certain amount of energy. When passing through the dynamic load buffer layer of the drilled hole structure, the pores and cracks formed by the drill hole absorb, refract, and reflect the energy through changes in wave impedance and deformation and damage to the surrounding rock and coal structure, reducing the transmission of dynamic load energy.

[0044] When the residual dynamic load passes through the energy-absorbing layer of the energy-absorbing slurry, the slurry's toughness buffers and absorbs the energy, further weakening the flow rate carried by the dynamic stress wave. At the same time, the anchoring end formed by the 20.0 cm slurry has an anchoring effect, improving the tensile and shear resistance of the transitional damage zone and preventing delamination failure. When the weak dynamic load is transmitted into the highly damaged area, the nano-scale high-strength slurry densifies and fills the shallow surrounding rock, increasing its mechanical properties, such as cohesion, internal friction angle, and elastic modulus, and strengthening the impact resistance and bearing capacity of the consolidated shallow fractured surrounding rock.

[0045] It can be seen that through the above-mentioned segmented grouting measures, a multi-layer impact-resistant structure of "structural energy absorption-slurry energy absorption-enhanced impact-resistant structure" is formed, which can give full play to the dynamic load absorption and impact resistance of the tunnel surrounding rock itself, and increase the surrounding rock stability of deep dynamic load tunnels.

[0046] The calculation formula for the surrounding rock damage degree is: ;

[0047] Where: V minis the minimum wave velocity value in the highly damaged area; V max is the maximum wave velocity value in the original rock stress zone; V d For depth d The wave velocity value at ; D d For depth d The degree of damage at the site;

[0048] Record the maximum and minimum wave velocities, calculate the damage degree of each measuring point under the synergistic coupling of excavation damage effect and mining effect according to the formula, and draw the damage curve that changes with the depth of the borehole. Figure 4 As shown in the figure, it can be seen that as the depth increases, the surrounding rock can be divided into a high damage zone, a transitional damage zone and an original rock stress zone. The maximum depth of the high damage zone is recorded ( h max ) Maximum depth of transition damage zone ( t max ).

[0049] Furthermore: the energy-absorbing slurry in the transitional damaged section in step 5 is a resin slurry energy-absorbing material, which has low viscosity and high ductility and can form a flexible support reinforcement layer;

[0050] Furthermore: the nano-based material in the highly damaged section in step 6 is a nano-based silica slurry, which is used to fill the tiny pores in the shallow surrounding rock of the tunnel, improve the density and cohesion between blocks, and improve the stability and impact resistance;

[0051] Furthermore: the length of the original rock stress zone is ≥ 2m.

[0052] Supplementary explanation: The dynamic load buffer layer of the bored structure is to increase the compressible space in the original rock stress zone, give full play to the energy absorption capacity of the surrounding rock through artificial structures, improve the energy dissipation coefficient and refractive index in the process of dynamic load transmission, and weaken the dynamic load amplitude of the tunnel surrounding rock by reducing the dynamic load energy transmittance; the energy-absorbing slurry buffer layer is to further absorb the transmitted surplus dynamic load and weaken the dynamic load amplitude in the highly damaged area; the shallow high-strength slurry reinforcement layer is to improve the strength and integrity of the shallow highly damaged area of ​​the tunnel, and improve the deformation resistance and stability of the shallow layer, so as to ensure the stability of the shallow surrounding rock under smaller dynamic load impact loads under the above conditions, and prevent the occurrence of nonlinear damage accidents such as impact ground pressure and large deformation of the tunnel surrounding rock.

[0053] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all included in the scope of protection of the present invention.

Claims

1. A graded grouting energy absorption and anti-impact method based on the degree of tunnel damage, characterized in that: The following steps are involved: Step 1: Drilling is carried out before grouting reinforcement. The holes are arranged on both sides and the roof of the tunnel surrounding rock. The holes are drilled perpendicular to the inner wall of the tunnel surrounding rock along the tunnel inclination, and the holes are evenly spaced. Step 2: Place the acoustic wave test probe close to the inner wall of the borehole, align and arrange them in parallel, and measure the wave velocity of the surrounding rock. Measure from shallow to deep with a measurement interval of 30.0 cm, and record the wave velocity value at each test point. Step 3: Make a secondary correction to the borehole depth based on the wave velocity evolution trend, and divide the borehole into zones from shallow to deep, namely, the crushing zone, the plastic zone, and the in-situ rock stress zone; Step 4: Analyze the wave velocity in the crushed area and the original rock stress area, and record the minimum wave velocity value V min and maximum wave velocity V max , calculate the surrounding rock damage degree, and divide the damaged area into high damage area, transition damage area and original rock stress area according to the damage degree result; Step 5: Seal the hole at 20.0 cm in the transition damage zone and the original rock stress section, and inject energy-absorbing slurry into this discontinuous interval; Step 6: After the energy-absorbing grouting is completed, the borehole opening is sealed, and nano-based grouting is performed in the highly damaged area. After the grouting is completed, the borehole opening is sealed; Step 7: Repeat steps 2 to 6 for the remaining holes; The calculation formula for the surrounding rock damage degree is: ； Where: V min is the minimum wave velocity value in the highly damaged area; V max is the maximum wave velocity value in the original rock stress zone; V d For depth d The wave velocity value at ; D d For depth d The degree of damage.

2. The method for absorbing energy and preventing impact by graded grouting based on the degree of tunnel damage according to claim 1 is characterized in that: The energy-absorbing slurry in the transition damage section in step five is a resin slurry energy-absorbing material.

3. The method for preventing impact by graded grouting based on roadway damage degree according to claim 1 is characterized in that: The nano-based material of the highly damaged section in step six is ​​nano-based silicon dioxide slurry.

4. The method for absorbing energy and preventing impact by graded grouting based on the degree of tunnel damage according to claim 1 is characterized in that: The length of the original rock stress zone is ≥2m.

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