Graded grouting energy absorption and scour prevention method based on roadway damage degree

Abstract

The invention discloses a graded grouting energy-absorbing and scour-preventing method based on roadway damage degree, and relates to the technical field of deep dynamic load roadway grouting processes, which is technically characterized by comprising the following steps: step 1, drilling construction is carried out before grouting reinforcement operation, drill holes are formed in two sides and a top plate of roadway surrounding rock, and the drill holes are formed in the top plate of the roadway surrounding rock; drilling holes perpendicular to the inner wall of the roadway surrounding rock along the roadway inclination, wherein the drilled holes are distributed at equal intervals; 2, the acoustic wave testing probes are tightly attached to the set position of the inner wall of the drill hole and arranged in parallel in an aligned mode, and surrounding rock wave velocity measurement operation is carried out. Measuring operation is carried out in sequence from shallow to deep, the measuring distance is 30.0 cm, and the wave velocity value of each test point is recorded; the technical effects are that flexible and rigid grouting materials cooperate with segmented grouting measures and technologies, a segmented and layered impact-resistant structure design concept is fused, an impact-resistant layer system structure is constructed from deep to shallow in sequence, and the impact resistance and energy dissipation capacity of roadway surrounding rock are greatly exerted.

Description

Technical Field

[0001] The present invention relates to the technical field of deep dynamic load roadway grouting technology, and specifically to a graded grouting energy absorption and impact prevention method based on roadway damage degree. Background Technique

[0002] As an important energy driving force for the modern economic development of the country, the safe exploitation of coal resources is an important guarantee for the healthy and green development of the national economy. With the increasing depletion of shallow coal resources, in order to promote the sustainable development of the national economy and ensure national energy security, "marching towards the deep" is the strategic direction of coal resource exploitation. As the depth of coal resource exploitation increases, the stress environment of deep roadways, the mechanical properties of roadway surrounding rocks, the spatial migration mode of overlying strata, and the coal and rock dynamic disaster manifestation mechanism become increasingly complex. The impact dynamic load formed by mining-induced mine tremors seriously affects the stability of roadways, resulting in continuous damage and deformation of roadways, and even causing the occurrence of non-linear dynamic disasters - rock bursts, posing a serious threat to the safety of mining personnel and the normal use of mining equipment. Therefore, considering the stress characteristics of deep roadways, it is urgent to study and propose effective support measures and methods suitable for deep roadways under dynamic load.

[0003] After roadway excavation, under the dual action of excavation unloading effect and mining-induced stress, the fissures in the shallow surrounding rock of the roadway are fully developed and the density of the fissure network is relatively high, resulting in the easy occurrence of bulging deformation, loosening, rib spalling and cracking, and even slag falling and delamination in the shallow surrounding rock of the roadway, damaging the integrity and stability of the roadway surrounding rock. As the depth of the roadway surrounding rock gradually increases, the degree of fissure development and the density of secondary fissures gradually decrease, and the stability of the roadway surrounding rock gradually increases until it no longer changes after entering the original rock stress area. Through the bonding and curing effect of the grout, the grouting technology can change the physical and mechanical properties of the roadway surrounding rock, enhance the cohesion between the surrounding rock blocks, reduce the porosity, and improve the bearing capacity and integrity of the roadway surrounding rock. It is a convenient, economical, fast and technically mature roadway support measure, which has been unanimously recognized and applied by many roadway support experts and scholars. Most of the existing grouting materials are silicate cement materials, which have a certain stiffness after coagulation and curing, but do not have the energy absorption and shock damping effect and the flexible support characteristics, and it is difficult to exert toughness under the action of impact dynamic load and weaken the damage effect of dynamic load impact on the roadway. Therefore, the energy-absorbing grout that absorbs energy through the deformation or structural damage of the grout material itself emerged as the times require, and its main materials are mostly epoxy resin, polyurethane or expanded perlite. However, compared with the energy carried by the impact dynamic load induced by the movement of overlying strata space, the energy absorption capacity of the energy-absorbing grout filled in the limited pore-fissure volume is significantly insufficient, and the effectiveness of relying on the energy-absorbing grout to fully absorb energy is controversial and lacks verification. It can be seen that through the surrounding rock grouting modification technology, giving full play to the synergistic bearing capacity and energy absorption effect of the surrounding rock and the grout is an effective and innovative research direction, so as to reduce the impact damage of the roadway dynamic load and avoid the deformation and dynamic instability of the roadway. At the same time, at present, only one of the above materials is mainly used for the roadway support grouting material, which is contrary to the principle of rigid and flexible collaborative support, and the support effect has great limitations and deficiencies. In addition, there is no unified definition standard for the grouting depth, which mainly depends on empirical judgment, and there is a lack of value-taking and judgment for the scientific grouting depth. If the grouting depth is too large, it will cause economic losses; on the contrary, it is easy to cause insufficient support strength and cannot meet the safety standards. With the increasing improvement of the mechanization degree and the accuracy of the acquisition equipment, by using the acoustic wave method to detect and determine the wave velocity value of the surrounding rock, the degree of fissure development and the initial damage area of the roadway surrounding rock can be effectively discriminated, providing a prerequisite guarantee for the implementation of scientific and effective grouting measures. Based on the acoustic wave detection technology, an energy-absorbing grouting support anti-impact method considering the initial damage of deep roadway is proposed. This method aims to accurately determine and divide the fissure distribution and damage area of the roadway surrounding rock through acoustic wave detection technology, so as to guide the drilling depth and grouting depth. Through the pore structure of the drill hole, the rigid and flexible grout sectional grouting technology, the energy absorption function of the deep surrounding rock of the roadway is greatly exerted, and the bearing capacity and anti-impact ability of the shallow surrounding rock are enhanced. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a hierarchical grouting energy absorption and impact prevention method based on roadway damage degree, which combines the importance and necessity of rigid grouting and flexible grouting materials for collaborative sectional grouting, and gives full play to and improves the energy absorption and bearing capacity of the roadway surrounding rock itself. It can not only provide scientific decision-making support for roadway grouting support, but also effectively reduce the damage degree of roadway deformation and impact phenomena, provide a safer guarantee for coal mine safety production, and has broad application prospects and social and economic value.

[0005] To achieve the above object, the present invention provides the following technical solutions: A hierarchical grouting energy absorption and impact prevention method based on roadway damage degree, comprising the following steps: Step 1: Before the grouting reinforcement operation, boreholes are constructed. The boreholes are arranged on both sides and the roof of the roadway surrounding rock, and are drilled perpendicular to the inner wall of the roadway surrounding rock along the roadway dip. The boreholes are equally spaced. Step 2: The acoustic wave test probes are closely attached to the set positions on the inner wall of the boreholes, arranged in alignment and parallel, and the wave velocity measurement operation of the surrounding rock is carried out. The measurement operation is carried out successively from shallow to deep, with a measurement spacing of 30.0 cm, and the wave velocity values at each test point are recorded. Step 3: The borehole depth is corrected twice according to the wave velocity evolution trend, and the boreholes are divided into regions, which are divided into a broken zone, a plastic zone and an in-situ stress zone from shallow to deep. Step 4: Analyze the wave velocities in the broken zone and the in-situ stress zone, and record the minimum wave velocity value V min and the maximum wave velocity value V max , calculate the surrounding rock damage degree, and divide the damaged area into a high damage area, a transition damage area and an in-situ stress area according to the damage degree result; Step 5: Seal the boreholes at 20.0 cm of the footage in the transition damage area and the in-situ stress section, and carry out energy absorption slurry grouting in this intermittent interval; Step 6: After the energy absorption grouting is completed, seal the borehole orifice, and carry out nano-based grouting in the high damage area; Step 7: Repeat Steps 2 to 6 for the remaining boreholes.

[0006] Preferably, the surrounding rock damage degree calculation formula is: ;

[0007] In the formula: V min is the minimum wave velocity value in the high damage area; V max is the maximum wave velocity value in the in-situ stress area; V d is the depth d at which the wave velocity value; D d is the depth dThe damage degree at the

[0008] Preferably, the energy-absorbing slurry in the transition damage section in Step 5 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.

[0009] Preferably, the nano-based material in Step 6 is nano-based silica slurry, which is used to fill the tiny pores in the shallow surrounding rock of the roadway, improve the density and the cohesion between blocks, and enhance the stability and impact resistance.

[0010] Preferably, the length of the virgin rock stress area is ≥ 2 m.

[0011] Compared with the prior art, the present invention provides a graded grouting energy-absorbing and impact-proof method based on the damage degree of the roadway, and has the following beneficial effects: Through the collaborative staged grouting measures and techniques of flexible and rigid grouting materials, the design concept of staged and hierarchical impact-resistant structures is integrated, and an impact-resistant layer system structure of "drilling structure dynamic load buffer energy-absorbing layer - energy-absorbing slurry buffer energy-absorbing layer - shallow high-strength slurry reinforcement layer" is constructed from deep to shallow in sequence, which greatly exerts the impact resistance and energy dissipation capacity of the roadway surrounding rock itself, and significantly improves the energy dissipation coefficient and the stability strength of the shallow surrounding rock of the roadway during the dynamic load transfer process through energy-absorbing and wave-dissipating means; Through the acoustic wave measurement technology, considering the initial damage of the roadway surrounding rock, the effective and scientific layout depth of the grouting boreholes is determined, overcoming the human error based on empirical judgment.

[0012] Through the extension of the grouting depth, a slurry solidification and anchoring structure is formed between the unstable layer and the stable layer. Since the slurry has certain shear and tensile resistance after solidification, an anchoring reinforcement structure can be formed to strengthen the bonding strength between layers and avoid the occurrence of deformation disasters such as separation, spalling, and overall bulging. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the layout of grouting boreholes in the roadway surrounding rock; Figure 2 It is a schematic diagram of the layout of acoustic wave test points for No. 1 and No. 2 boreholes; Figure 3 It is a curve diagram of the wave velocity distribution of the measuring points of No. 1 and No. 2 boreholes; Figure 4 It is a damage curve diagram of No. 1 and No. 2 boreholes at different depths; Figure 5 It is a curve diagram of the maximum depth of the damage area at different borehole heights; Figure 6 It is a curve diagram of the maximum depth of the transition damage area of different boreholes; Figure 7 It is a curve distribution diagram of the critical depth of the damage area; Figure 8Schematic diagram of sectional grouting for roadway surrounding rock; Figure 9 Schematic diagram of layered impact-resistant structure after sectional grouting of roadway surrounding rock. Specific implementation manner

[0014] In the present invention, unless otherwise specified, the orientations such as "upper, lower" are generally in the direction shown in the drawings, or in the vertical, perpendicular or gravitational direction; similarly, for the convenience of understanding and description, "left, right" are generally in the left and right shown in the drawings; "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms are not used to limit the present invention.

[0015] Please refer to Figures 1-9 , the present invention provides a technical solution for a hierarchical grouting energy absorption and impact prevention method based on roadway damage degree, including the following steps: Step 1: Before the grouting reinforcement operation, boreholes are constructed. The boreholes are arranged on both sides and the roof of the roadway surrounding rock. Boreholes are drilled perpendicular to the inner wall of the roadway surrounding rock along the roadway dip. The boreholes are equally spaced, as Figure 1 shown. The specific number of boreholes can be adjusted adaptively without specific limitation. The borehole diameter is 10.0 cm and the borehole depth is 10.0 m. Subsequently, the borehole spacing and depth are corrected according to the grouting effect. After the borehole operation, the coal powder and rock debris in the boreholes are removed; Step 2: The acoustic wave test probe is closely attached to the set position on the inner wall of the borehole and arranged in parallel alignment to carry out the surrounding rock wave velocity measurement operation. The measurement operation is carried out from shallow to deep in sequence, as Figure 2 shown (where the serial numbers ①-⑥ represent the sequential measurement and do not limit the number of measurement points). The measurement spacing is 30.0 cm, and the wave velocity values of each test point are recorded; Further: Taking the wave velocity measurement between the No. 1 borehole and the No. 2 borehole as an example, as Figure 2 shown, acoustic wave measurement points are sequentially set at intervals of 30.0 cm from shallow to deep along the grouting borehole. The transmitting end and the receiving end of the acoustic wave measurement are respectively arranged at the corresponding measurement points in the No. 1 borehole and the No. 2 borehole. The probe is closely attached to the borehole surface to complete 1 acoustic wave measurement. Then, the wave velocity measurement work of the remaining measurement points is sequentially completed from shallow to deep, and the wave velocity measured at each measurement point is recorded and a curve is drawn, as Figure 3 shown (the test points are sequentially numbered and the wave velocity change curve is drawn). When the wave velocity measurement shows a high value and is stable, the wave measurement working face can be ended; Step 3: The borehole depth is corrected secondly according to the wave velocity evolution trend, and the boreholes are divided into regions, which are divided into a broken zone, a plastic zone and an original rock stress zone from shallow to deep; Supplementary note: Due to the obvious excavation damage effect in the surrounding rock of deep roadway, the surrounding rock of the roadway can be divided into a broken zone, a plastic zone and an original rock stress zone from shallow to deep in turn. This results in a three-stage evolution trend of wave velocity measurement, namely "low-value fluctuation, gradually increasing, high-value stable fluctuation", which shows a spatial correspondence with the damage and fracture zone. If the wave velocity measurement value is in the "gradually increasing" evolution stage, continue to drill holes until the "high-value stable fluctuation" stage appears, and it is necessary to ensure that the distance of the "high-value stable fluctuation stage" is more than 2.0 m. The drilling depth is corrected twice according to the above wave velocity distribution law.

[0016] Step 4: Analyze the wave velocities in the broken zone and the original rock stress zone, and record the minimum wave velocity value V min and the maximum wave velocity value V max , calculate the surrounding rock damage degree, and divide the damage area into a high damage area, a transition damage area and an original rock stress area according to the damage degree result; It should be noted that: the wave velocity range in the high damage area is 0 - 2.0 Km / s; the wave velocity range in the transition damage area is 2.0 - 4.0 Km / s; 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 specifically according to the specific construction conditions and are not the only limiting conditions; Step 5: Seal the holes at 20.0 cm of the footage in the transition damage area and the original rock stress section, and conduct energy-absorbing slurry grouting in this intermittent interval. When the grouting pressure suddenly rises and the flow rate significantly decreases, stop grouting. As Figure 8 shown, the holes in the transition damage area and the original rock stress area are sealed and grouted through the No. 1 and No. 2 grout plugs; Step 6: After the energy-absorbing grouting is completed, seal the hole orifice of the drill hole, and conduct nano-based grouting in the high damage area. When the grouting pressure suddenly rises and the flow rate significantly decreases, stop grouting. After the grouting is completed, seal the hole orifice of the drill hole. The holes in the transition damage area and the high damage area are sealed and grouted through the No. 2 and No. 3 grout plugs; Step 7: Repeat Steps 2 to 6 for the remaining drill holes; Repeat Steps 2 to 6 in the remaining grouting drill holes for sectional grouting. The result after grouting is as Figure 9 shown. The structure of the surrounding rock of the roadway can be divided into: a nano-level high-strength grouting reinforcement layer, an energy-absorbing slurry energy-absorbing layer and a drill hole structure dynamic load buffer layer from shallow to deep in turn. The advantage of its layered combined impact-resistant structure is that it can give full play to the energy-absorbing and impact-resistant characteristics of the surrounding rock of the roadway itself, can greatly absorb the energy of dynamic load shock waves, and increase the bearing capacity and impact resistance of the surrounding rock of the roadway.

[0017] Meanwhile, after the slurry solidifies, the 20.0-cm slurry column can anchor the highly damaged zone and the transition damaged zone, and can also anchor the transition damaged zone and the original rock stress zone, improving the bonding force between layers and avoiding large deformations and impact failures of the roadway caused by separation phenomena. Specifically, when a far-field dynamic load is generated, the dynamic load stress carries a certain amount of energy. When passing through the dynamic load buffer layer of the borehole structure, due to the pore and crack structures formed by the borehole, the energy is absorbed, refracted, and reflected through changes in wave impedance and deformation and failure of the surrounding rock coal body structure, reducing the transmission of dynamic load energy.

[0018] When the residual transmitted dynamic load passes through the energy-absorbing slurry layer, due to the certain toughness of the energy-absorbing slurry, the energy can be buffered and absorbed, further weakening the energy carried by the dynamic load 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 transition damaged zone and avoiding separation failure. When the weak dynamic load transmits into the highly damaged zone, due to the compaction and filling of the nano-scale high-strength slurry in the shallow surrounding rock, the mechanical properties of the shallow surrounding rock are increased, such as cohesion, internal friction angle, and elastic modulus, strengthening the impact resistance and bearing capacity of the consolidated shallow broken surrounding rock.

[0019] It can be seen that through the above segmented grouting measures, a multi-layer impact-resistant structure of "structural energy absorption - slurry energy absorption - strengthened impact-resistant structure" is formed, which can exert the dynamic load absorption capacity and impact resistance of the roadway surrounding rock itself, increasing the stability of the surrounding rock of deep dynamic load roadways.

[0020] The calculation formula for the degree of surrounding rock damage is: ;

[0021] In the formula: V min is the minimum wave velocity value in the highly damaged zone; V max is the maximum wave velocity value in the original rock stress zone; V d is the depth d at which the wave velocity value is located; D d is the depth d at which the damage degree is located; Record the maximum wave velocity and the minimum wave velocity, calculate the damage degree under the synergistic coupling action of the excavation damage effect and the mining-induced effect at each measuring point according to the formula, and draw the damage curve varying with the depth of the borehole. As Figure 4 shown, it can be seen that along with the increase in depth, the surrounding rock can be divided into a highly damaged zone, a transition damaged zone, and an original rock stress zone in sequence. Record the maximum depth of the highly damaged zone ( h max ), and the maximum depth of the transition damaged zone ( t max ).

[0022] Furthermore: The energy-absorbing slurry in the transition damage section described 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; Furthermore: The nano-based material in the highly damaged section described in step six is nano-based silica slurry, which is used to fill the tiny pores in the shallow surrounding rock of the roadway, improve the density and the cohesion between blocks, and enhance the stability and impact resistance; Furthermore: The length of the virgin rock stress zone ≥ 2m.

[0023] Supplementary description: The dynamic load buffer layer of the borehole structure is to increase the compressible space of the virgin rock stress zone, utilize the energy-absorbing capacity of the surrounding rock through an artificial structure, improve the energy dissipation coefficient and refraction coefficient during the dynamic load transfer process, and weaken the dynamic load amplitude of the roadway surrounding rock by reducing the dynamic load transmittance; the energy-absorbing slurry buffer layer is to further absorb the transmitted surplus dynamic load and weaken the dynamic load amplitude of 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 roadway, enhance the anti-deformation and stability of the shallow layer, so as to ensure the stability of the shallow surrounding rock under a small dynamic load impact load under the above conditions and prevent the occurrence of non-linear failure accidents such as rock bursts and large deformations in the roadway surrounding rock.

[0024] 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 replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all covered by the protection scope of the present invention.

Claims

1. A grading grouting energy absorption and impact prevention method based on roadway damage degree, characterized in that, It includes the following steps: Step 1: Before the grouting reinforcement operation, drilling construction is carried out. The drill holes are arranged on both sides and the roof of the roadway surrounding rock. Drill holes perpendicular to the inner wall of the roadway surrounding rock along the roadway dip, and the drill holes are equally spaced; Step 2: Press the acoustic wave test probe tightly against the set position on the inner wall of the drill hole, arrange them in alignment and parallel, carry out the measurement of the wave velocity of the surrounding rock, and carry out the measurement from shallow to deep in turn. The measurement spacing is 30.0 cm, and record the wave velocity values of each test point; Step 3: Make a secondary correction to the drill hole depth according to the wave velocity evolution trend, and divide the drill holes into regions. From shallow to deep, they are divided into a broken zone, a plastic zone and a virgin rock stress zone; Step 4: Analyze the wave velocities in the fractured zone and the virgin rock stress zone, and record the minimum wave velocity value V min and the maximum wave velocity value V max , calculate the surrounding rock damage degree, and divide the damage zone into a highly damaged zone, a transitional damaged zone, and a virgin rock stress zone according to the damage degree results; Step 5: Seal the drill hole at a depth of 20.0 cm in the transition damage zone and the virgin rock stress section, and carry out energy-absorbing slurry grouting in this discontinuous interval; Step 6: After the energy-absorbing grouting is completed, seal the drill hole orifice, carry out nano-based grouting in the highly damaged zone, and seal the drill hole orifice after the grouting is completed; Step 7: Repeat Steps 2 to 6 for the remaining drill holes.

2. The grading grouting energy absorption and impact prevention method based on roadway damage degree according to claim 1, characterized in that The calculation formula for the surrounding rock damage degree is as follows: ; In the formula: V min is the minimum wave velocity value in the highly damaged area; V max is the maximum wave velocity value in the virgin rock stress area; V d is the depth d at which the wave velocity value is located; D d is the depth d at which the damage degree is located.

3. A grading grouting energy absorption and impact prevention method based on roadway damage degree according to claim 1, characterized in that: The energy-absorbing slurry in the transition damage section described in Step 5 is a resin slurry energy-absorbing material.

4. A grading grouting energy absorption and impact prevention method based on roadway damage degree according to claim 1, characterized in that: The nano-based material in the highly damaged section described in Step 6 is nano-based silica slurry.

5. A grading grouting energy absorption and impact prevention method based on roadway damage degree according to claim 1, characterized in that: The length of the virgin rock stress zone ≥ 2m.

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