A floor grouting induced roadway dynamic destruction risk prediction method and device

Abstract

This invention discloses a method and equipment for predicting the risk of dynamic damage to roadways induced by floor grouting, belonging to the field of coal and rock dynamic disaster prevention technology. First, it determines whether the immediate floor is a hard rock stratum with a thickness greater than or equal to 1m. Then, based on the rock stratum's attitude, mechanical properties, ground stress, roadway width, and lateral support pressure, the critical grouting pressure causing damage to the hard immediate floor stratum is calculated. Finally, the ratio of the critical grouting pressure causing damage to the hard immediate floor stratum to the design grouting pressure is defined as the roadway dynamic damage safety factor, quantitatively assessing the risk of dynamic damage to roadways induced by floor grouting. This invention relates to a method for predicting the risk of dynamic damage to roadways induced by floor grouting, enabling the evaluation of the risk level of dynamic damage to roadways induced by floor grouting in a region. It has strong operability and is particularly suitable for risk prediction of dynamic damage to roadways induced by floor grouting in coal mines.

Description

Technical Field

[0001] This invention relates to the field of coal and rock dynamic disaster prevention and control technology, specifically to a method and equipment for predicting the risk of roadway dynamic damage induced by bottom grouting. Background Technology

[0002] Some coal mines contain confined water in the floor. As mining progresses to deeper levels, the likelihood of floor water inrush increases. To effectively prevent floor water inrush disasters, pre-mining regional floor grouting modification has become a common technique, constructing artificial water-resistant layers to reduce the risk of water inrush. However, under the combined effects of grouting and mining, roadway dynamic damage frequently occurs. Therefore, risk prediction of roadway dynamic damage after floor grouting implementation is particularly important.

[0003] The prior art disclosed in CN114439514A describes a method for grouting reinforcement to prevent floor heave in coal mine roadways. This method involves drilling holes in the roadway floor and then injecting prepared mortar into these pre-drilled holes using grouting equipment. The mortar fills the fissures in the floor rock through the cracks in the borehole wall. Simultaneously, under grouting pressure, the high-pressure grout directly compacts and closes some small fissures in the floor rock. Essentially, this method seals the original fissures in the immediate floor rock strata through grouting, thereby enhancing the strength of the immediate floor rock strata and preventing water from entering the immediate floor through these original fissures and causing softening and deformation. However, it only considers preventing floor heave and does not consider whether the geological environment is suitable for grouting reinforcement, the potential destructive effect of grouting reinforcement on the immediate floor structure, or whether the immediate floor exhibits a dynamic effect when it fails under grouting pressure. Currently, there is a lack of operational methods for predicting the risk of roadway dynamic damage induced by floor grouting. The only way to predict the possibility of roadway damage is to observe the grouting pressure and the parameters of roadway floor deformation during the implementation of floor grouting modification, and to determine whether the roadway floor damage has a dynamic effect based on the final damage situation. Summary of the Invention

[0004] Purpose of the invention: This invention provides a method and equipment for predicting the risk of dynamic damage to roadways induced by floor grouting. The steps are simple, easy to quantify, and highly operable. By defining the ratio of the critical grouting pressure that causes damage to the hard direct bottom rock layer to the design grouting pressure as the safety factor for dynamic damage to the roadway, the risk of dynamic damage to roadways induced by floor grouting can be predicted. It has strong scientific, economic and operable characteristics.

[0005] Technical Solution: To achieve the above objectives, this invention discloses a method for predicting the risk of dynamic damage to roadways induced by floor grouting. Before performing floor grouting to prevent water inrush disasters, the following steps are performed: S1. Determine whether the direct bottom of the tunnel is a hard rock layer with a thickness of 1m or more; S2. Calculate the critical grouting pressure that causes the current roadway's hard, direct bottom rock layer to fail; S3. Calculate the roadway dynamic damage safety factor. The roadway dynamic damage safety factor can be used to determine the risk of roadway dynamic damage induced by floor grouting in the current roadway, and then determine whether pre-mining floor grouting modification can be carried out.

[0006] Furthermore, when it is determined that there is an aquifer with a risk of water inrush below the current floor, in order to prevent water inrush disasters, a certain rock layer between the aquifer and the roadway floor is selected for grouting and transformation into a water-resistant layer. If the grouting pressure of the grouting layer exceeds the resistance capacity of the roadway floor, the roadway floor will be damaged. If the vibration energy released when the floor is damaged is large, it will have a significant dynamic effect, manifested as dynamic damage. The method for judging whether the roadway floor damage has a significant dynamic effect is as follows: by sampling from the roadway floor, it is determined whether the roadway floor is sandstone or other rock layers with a uniaxial tensile strength greater than 4MPa. Roadway floors that meet the conditions are judged as hard floor rock layers. At the same time, the thickness of the roadway floor is sampled to determine whether it is greater than or equal to 1m.

[0007] Furthermore, based on the measured information on the attitude of the rock strata at the bottom of the tunnel, the mechanical properties of the rock strata, the in-situ stress, as well as the tunnel width and the lateral support pressure of the tunnel, the critical grouting pressure that causes failure of the hard, direct bottom rock strata is calculated. The calculation formula is as follows: , In the formula, The critical grouting pressure required to cause damage to the hard, direct underlying rock layer, expressed in MPa; The elastic modulus of the hard, direct underlying rock layer, expressed in GPa. The moment of inertia of the cross section of the hard, direct bottom rock layer, in meters. 4 ; The elastic modulus of each rock layer between the hard, direct bottom rock layer and the grouting layer is expressed in GPa. The moment of inertia of the cross sections of each rock layer between the hard, direct bottom rock layer and the grouting layer, in meters. 4 ; Tensile strength of the hard, direct underlying rock layer, in MPa; The horizontal stress is derived from the lateral support pressure of the roadway, expressed in MPa. The horizontal structural stress is expressed in MPa, perpendicular to the tunnel axis. Thickness of the hard, direct bottom rock layer, in meters; The width of the alleyway is measured in meters (m). The depth of the loosened zone in the sidewall of the tunnel, in meters; This represents the lateral support pressure of the roadway, in MPa.

[0008] Furthermore, the critical grouting pressure that causes failure of the hard, direct underlying rock layer is defined. With design grouting pressure The ratio is the roadway dynamic failure safety factor K, which quantitatively assesses the risk of roadway dynamic failure induced by floor grouting; the roadway dynamic failure safety factor K is calculated as follows: , In the formula, The critical grouting pressure required to cause damage to the hard, direct underlying rock layer, expressed in MPa; The threshold grouting pressure is preset manually, in MPa.

[0009] Furthermore, the safety factor of roadway dynamic damage The grading criteria are as follows: When the roadway dynamics are disrupted, the safety factor is reduced. When the value is ≤1, the risk of dynamic damage to the roadway induced by bottom grouting is at a high level; When the roadway dynamic failure safety factor is 1 < When the value is ≤1.5, the risk of dynamic damage to the roadway induced by grouting of the floor slab is at a moderate level; When the roadway dynamics are disrupted, the safety factor is reduced. When the value is >1.5, the risk of dynamic damage to the roadway induced by bottom grouting is low. Based on the roadway dynamic damage safety factor, when the risk of roadway dynamic damage induced by floor grouting is low, floor grouting can be carried out normally; when the risk of roadway dynamic damage induced by floor grouting is medium to high, the location of the grouting layer and grouting parameters, such as orifice pressure and grout specific gravity, need to be reconsidered, or grouting modification work may not be carried out.

[0010] A computer device includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the method for predicting the risk of dynamic damage to roadways induced by grouting of the foundation plate.

[0011] Beneficial effects: Based on the critical grouting pressure and design grouting pressure that cause damage to hard direct bottom rock layers, this method can quantitatively assess the risk of roadway dynamic damage induced by floor grouting by defining the roadway dynamic damage safety factor, thus providing theoretical guidance for mine production organization and floor grouting modification. Attached Figure Description

[0012] Figure 1 This is a flowchart of the method for predicting the risk of roadway dynamic damage induced by bottom grouting according to the present invention.

[0013] Figure 2This is a schematic diagram of the mechanical model of the incision plate in an embodiment of the present invention; Figure 2 (a) is a complete mechanical model of the grouting layer below K2 and the roadway floor. Figure 2 (b) is the mechanical model of the fixed beam with cut-eye base plate.

[0014] Figure 3 This is a schematic diagram of the mechanical model of the semi-fixed beam with a cut-eye base plate in an embodiment of the present invention. Detailed Implementation

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] like Figure 1 As shown, this invention discloses a risk prediction method for dynamic failure of roadway floor induced by floor grouting, specifically including the following steps: S1 determines whether the immediate bottom is a hard rock layer with a thickness greater than or equal to 1m.

[0017] S2, based on the rock strata attitude, rock strata mechanical properties, in-situ stress, tunnel width, and lateral support pressure of the tunnel, calculates the critical grouting pressure that causes failure of the hard direct subsoil. The calculation formula is as follows: , In the formula, The critical grouting pressure required to cause damage to the hard, direct underlying rock strata is MPa; The elastic modulus of the hard, direct underlying rock layer, in GPa; The moment of inertia of the cross section of the hard, direct bottom rock layer is m. 4 ; The elastic modulus of each rock layer between the hard, direct bottom rock layer and the grouting layer, in GPa; The moment of inertia of the cross sections of each rock layer between the hard, direct bottom rock layer and the grouting layer, m 4 ; The tensile strength of the hard, direct underlying rock layer, in MPa; The horizontal stress is derived from the lateral support pressure of the roadway, measured in MPa. The horizontal structural stress is measured in MPa and is perpendicular to the tunnel axis. The thickness of the hard, direct bottom rock layer is in meters (m). The width of the alley is half its width, in meters. The depth of the loosened zone in the sidewall of the tunnel, in meters; The pressure is the lateral support pressure of the roadway, in MPa.

[0018] The rock strata between the hard, direct bottom layer and the grouting layer are considered as a whole. This represents the total flexural stiffness of the composite rock strata. Based on the composite beam theory of rock strata: when there is no delamination or slippage between rock layers, multi-layered rock strata can be calculated as a composite beam, and the total flexural stiffness is the sum of the stiffnesses of each layer. The calculation formula is as follows: =∑E i ·I i , i=1,2,…,n; n is the number of rock layers between the hard direct bottom rock layer and the grouting layer; Where E represents the elastic modulus and I represents the moment of inertia of the cross section; Using the formula: Calculate the design grouting pressure of the grouting layer. In the formula, The grouting pump pressure at the grouting hole opening is in MPa. The height, in meters, is the distance from the grouting hole opening to half the length of the grouting layer. The density of the grout is expressed in g / cm³. 3 ; The height of the water column at 1 / 2 of the grouting section before grouting.

[0019] S3 is defined as the critical grouting pressure that causes failure of the hard, direct subsurface rock. With design grouting pressure The ratio is the roadway dynamic failure safety factor K, which is used to quantitatively assess the risk of roadway dynamic failure induced by floor grouting.

[0020] The safety factor for dynamic failure of a roadway is calculated using the following formula. : In the formula, The safety factor for dynamic damage to the roadway; The critical grouting pressure required to cause damage to the hard, direct underlying rock strata is MPa; The grouting pressure is designed in MPa.

[0021] Considering that the values ​​of various parameters may differ from the actual site conditions, a roadway dynamic failure safety factor is defined. The grading criteria are as follows: When the roadway dynamics are disrupted, the safety factor is reduced. When the value is ≤1, the risk of dynamic damage to the roadway induced by bottom grouting is at a high level; When the roadway dynamic failure safety factor is 1 < When the value is ≤1.5, the risk of dynamic damage to the roadway induced by grouting of the floor slab is at a moderate level; When the roadway dynamics are disrupted, the safety factor is reduced. When the value is greater than 1.5, the risk of dynamic damage to the roadway induced by grouting of the bottom plate is low.

[0022] The present invention will be further described below with reference to the embodiments.

[0023] S1, as shown in Table 1, the bottom of the working face of a certain mine is quartz sandstone, which is a hard rock layer with a thickness of 1.85m.

[0024] S2, the thickness of all rock layers between the direct bottom of the coal seam and the grouting layer is shown in Table 1, and the elastic modulus of all rock layers between the direct bottom of the coal seam and the grouting layer is shown in Table 2.

[0025] Table 1. Thickness and depth of the bottom strata of the cut: ; Table 2 Elastic modulus of rock strata determined: ; Based on the attitude and physical and mechanical properties of the rock strata near the cut, as shown in Table 2, the following can be calculated: It is 10.71.

[0026] Calculate the flexural stiffness of all rock layers between the hard, direct bottom rock layer and the grouting layer, which is also the flexural stiffness of the composite beam: This bending stiffness is used in calculating the critical grouting pressure that causes failure of the hard, direct bottom rock layer. It is used at times.

[0027] The hard, direct bedrock strata of the roadway are considered as a supporting beam, and the ultimate bearing capacity of the supporting beam is derived. The hard, direct bedrock strata are the main body of dynamic failure of the floor. The hard, direct bedrock strata are simplified as a supporting beam, with the support point of the supporting beam at the boundary of the loosened zone on both sides of the cut. The boundary of the loosened zone on both sides of the cut is considered as the boundary of the supporting beam, and the support pressure within the loosened zone of the cut is linearly simplified. The grouting pressure of the grouting layer is approximately replaced by a uniformly distributed load, directed vertically upwards. For example... Figure 2 (a) represents the complete mechanical model between the grouting layer below K2 and the roadway floor. The rock strata between the hard direct bottom rock layer and the K2 limestone aquifer are regarded as a composite beam. The rock strata of the composite beam are in close contact, without separation or relative slippage. A rectangular coordinate system is established with the center of the fixed support beam as the origin, the horizontal direction to the right as the positive x-axis, and the vertical direction downward as the positive y-axis.

[0028] Derivation of the formula for the critical grouting pressure that causes failure of hard, direct bottom rock layers: Based on the bending differential equation of a fixed beam in mechanics of materials and the interlaminar deformation compatibility condition: assuming that the deflection at the contact points is completely equal: ,get and Relational expressions between the two: (1), in: Represents the elastic modulus of rock strata, in GPa; The moment of inertia of the beam section is expressed in m.4 ; Indicates the total distributed load intensity on the beam (positive downwards); Represents rock stratum deflection, in meters (m). This represents the critical bearing capacity of hard rock strata, expressed in MPa.

[0029] To facilitate subsequent formula derivation, the symbols are defined as follows: (1) Bending moment Positive is defined as causing tension at the bottom of the beam (i.e., concave bending, with positive bending moment causing tensile stress at the bottom). (2) The downward load is positive. (Indicates downwards); (3) Corner In the points, using (Considering the agreement, the scoring conditions are as follows) to satisfy and ); (4) Other parameters: half width of the tunnel Loosening zone depth Half beam length Lateral support pressure of the incision eye The lower surface of the beam bears a uniformly distributed load. .

[0030] in: Indicates bending moment (unit: N·m); This represents the angle of rotation (slope, dimensionless or rad) of the beam at position x. This represents the lateral support pressure coefficient of the cut eye (dimensionless). This indicates the unit weight of rock (unit: kN / m). 3 ); Indicates the depth of the tunnel (unit: m).

[0031] based on Figure 2 (b) Deriving the critical bearing pressure q on a hard, direct bottom stratum 硬 The derivation process is as follows: (1) Establish a semi-fixed beam model: considering Figure 2 (b) Due to the symmetry of the mechanical model of the fixed-support beam in the middle plate, it is simplified to a semi-fixed-support beam mechanical model. Let the left endpoint of the semi-fixed-support beam mechanical model be the midpoint of the fixed-support beam model in the middle plate, denoted as... The right end point of the semi-fixed beam model is considered as Semi-fixed beam model, such as Figure 3 As shown; Boundary conditions: Due to the left-right symmetry of the semi-fixed beam mechanical model, shear force , ; The location is a fixed branch. ;in: This represents the shear force (in N) at position x of the fixed beam. Equivalent uniformly distributed load on the beam (Downward is positive): When position x satisfies: If x is located in the tunnel area, then the beam only bears an upward uniformly distributed load. Equivalent uniformly distributed load ; When position x satisfies: Then it is determined that x is in the support pressure zone: the beam is subjected to the support pressure of and Then the equivalent uniformly distributed load ; Where: P0 is the lateral support pressure, MPa.

[0032] (2) Use formula (2) to integrate and find the shear force at a certain point on the fixed beam. : (2), in, Express the differential equation of shear force on a fixed beam, with the following boundary conditions: (Central symmetry); When position x satisfies: When it satisfies formula (3): (3), When position x satisfies: When the conditions are met, formulas (4) and (5) are satisfied: (4), (5).

[0033] (3) Integrate to find the bending moment at a certain point on the fixed beam. : (6), In the formula Express the differential equation of the bending moment acting on a fixed beam. Indicates the bending moment at the center of the fixed beam; When position x satisfies: hour: (7), (8), According to formula (8): .

[0034] When position x satisfies: hour: (9), (10), (11), By combining equations (9), (10), and (11), we can obtain: (12), Substituting equation (12) into equation (9), we get: (13), (14), Specifically: Solve for the bending moment at x=l of the fixed beam.

[0035] (4) Integrate to find the rotation angle at a certain point of the fixed beam. ,based on Solve : in: This indicates that the rotation angle at x=l in the semi-fixed beam mechanical model is 0; This represents the bending moment at x=0 in the fixed beam in the semi-fixed beam mechanical model; Angle equation: , ; have to: , (15), (16), Adding equations (15) and (16) together, we get: (17), (18).

[0036] (5) Substituting into equation (14), we can obtain the solution. Therefore, we can obtain and The expression: (19), (20), in: This represents the bending moment at a point in a semi-fixed beam mechanical model. This represents the bending moment at x=a in the mechanical model of a semi-fixed beam; This represents the bending moment at x=l in the mechanical model of a semi-fixed beam.

[0037] (6) Assume that the failure of the hard, direct bottom rock layer is dominated by the central negative bending moment and the vertical upward load This causes tension at the top interface in the middle of the fixed beam, introducing horizontal stress (assuming it is uniform compressive stress). , After the action of compression, a first-order theory approximation is used (linear superposition theory: axial force does not affect the bending moment distribution, but it does affect the stress state). Second-order effects are not considered in the semi-fixed beam mechanical model for the time being. (Effect). The normal stress on the beam section is equal to the sum of the original horizontal stress and the bending normal stress of the rock strata, that is: (twenty one), in: This represents the normal stress on the beam cross section (unit: MPa). Represents total horizontal stress (including horizontal structural stress) Lateral support pressure on both sides of the cut eye The transformed horizontal stress, i.e. (Unit: MPa) This indicates the distance from the neutral axis of the fixed beam to the bottom surface. Top surface , At the center of the fixed beam place, (Upward load) When the load is dominant, it causes tension at the top interface and compression at the bottom. The bending stress at the top interface is: (twenty two), Where: I is the moment of inertia of the fixed beam section, m 4 ; The total stress at the top interface of the beam is: (twenty three), Failure conditions of hard, direct bottom rock layers: The maximum tensile stress at the top interface reaches the tensile strength of the rock. ,Right now When the hard, direct underlying rock layer is destroyed, that is: (twenty four), We can obtain: (25), Combined equations (18) and (25), and (Upward load) (When dominant) the critical load of the fixed beam is obtained : (26), In the mechanical model of a semi-fixed beam, the beam's cross-sectional width is temporarily disregarded. Substituting into equation (26), we can obtain the critical load that causes failure of the hard, direct bottom rock layer: (27), Substituting equation (27) into equation (1) and rearranging, we obtain the critical grouting pressure that causes damage to the hard, direct bottom rock layer: (28), The critical grouting pressure causing failure of the hard, direct subsurface rock layer is calculated using the following formula. : .

[0038] Example: The width of the cut in a certain mine is 8.6m, so we take 4.3m. The depth of the loosened zone of the cut is 3.8m. According to the geostress measurement results of the nearby area, the horizontal structural stress in the vertical direction of the cut is 12.72MPa. The burial depth of the cut is 530.58m, and the self-weight stress σcz is about 13.26MPa. According to the numerical simulation results, the lateral support pressure concentration coefficient Kconcentration of the cut side is taken as 1.2, so the lateral support pressure of the cut side is 15.92MPa. The lateral pressure coefficient Klateral pressure is taken as 0.3. The horizontal stress increment converted from the lateral support pressure of the cut is about = σcz × (Kconcentration - 1) × Klateral pressure = 0.80MPa.

[0039] Based on the above parameters and the relevant parameters in Tables 1 and 2, the critical grouting pressure that causes damage to the hard, direct bottom rock layer is obtained. It is 14.41 MPa; The height from the grouting hole opening to half the height of the grouting layer. Approximately 550m, grouting pump pressure at the orifice. Approximately 10 MPa, grout density Take 1.5g / cm 3 Water column height at 1 / 2 of the grouting section before grouting The design grouting pressure for the grouting layer is calculated using the following formula, given a depth of 255m. : , Based on the above parameters, the design grouting pressure for the grouting layer is obtained. It is 15.7 MPa; Define the critical grouting pressure that causes failure of hard, direct subsurface rock layers. With design grouting pressure The ratio is the safety factor for dynamic failure of the roadway. The safety factor for dynamic failure of the roadway is calculated using the following formula. : , Based on the above parameters, the roadway dynamic failure safety factor is obtained. Approximately 0.92; Considering that the values ​​of various parameters may differ from the actual site conditions, the roadway dynamic failure safety factor... The grading criteria are as follows: When the roadway dynamics are disrupted, the safety factor is reduced. When the value is ≤1, the risk of dynamic damage to the roadway induced by bottom grouting is at a high level; When the roadway dynamic failure safety factor is 1 < When the value is ≤1.5, the risk of dynamic damage to the roadway induced by grouting of the floor slab is at a moderate level; When the roadway dynamics are disrupted, the safety factor is reduced. When the value is >1.5, the risk of dynamic damage to the roadway induced by bottom grouting is low. Based on this, the risk of roadway dynamic damage induced by grouting in the cut area is determined to be high, and the grouting parameters (orifice pressure and grout specific gravity) need to be reconsidered, or grouting modification work should not be carried out.

[0040] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiment based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the risk of dynamic damage to roadways induced by grouting of the foundation plate, characterized in that, Before performing grouting of the foundation slab to prevent sudden water inrush disasters, the following steps should be performed: S1. Determine whether the direct bottom of the tunnel is a hard rock layer with a thickness of 1m or more; S2. Calculate the critical grouting pressure that would cause damage to the direct bottom rock layer of the roadway, which is currently determined to be a hard rock layer. S3. Calculate the roadway dynamic damage safety factor, and use the roadway dynamic damage safety factor to judge the risk of roadway dynamic damage induced by floor grouting in the current roadway, and then judge whether pre-mining floor grouting modification can be carried out.

2. The method for predicting the risk of roadway dynamic damage induced by bottom grouting according to claim 1, characterized in that, When it is determined that there is an aquifer with a risk of water inrush below the current floor, in order to prevent water inrush disasters, a certain rock layer between the aquifer and the roadway floor is selected for grouting to transform it into a water-resistant layer. If the grouting pressure of the grouting layer exceeds the resistance capacity of the roadway floor, the roadway floor will be damaged. If the vibration energy released when the floor is damaged is large, it will have a significant dynamic effect, which manifests as dynamic damage. The method for judging whether the roadway floor damage has a significant dynamic effect is as follows: by sampling from the roadway floor, it is determined whether the roadway floor is sandstone or other rock layers with a uniaxial tensile strength greater than 4MPa. Roadway floors that meet the conditions are judged as hard floor rock layers. At the same time, the thickness of the roadway floor is sampled to determine whether it is greater than or equal to 1m.

3. The method for predicting the risk of roadway dynamic damage induced by bottom grouting according to claim 1, characterized in that, Based on the measured information on the attitude, mechanical properties, and in-situ stress of the roadway floor strata, as well as the roadway width and lateral support pressure, the critical grouting pressure that causes failure of the hard, direct floor strata is calculated. The calculation formula is as follows: ， In the formula, The critical grouting pressure required to cause damage to the hard, direct underlying rock layer, expressed in MPa; The elastic modulus of the hard, direct underlying rock layer, expressed in GPa. The moment of inertia of the cross section of the hard, direct bottom rock layer, in meters. 4 ; The elastic modulus of each rock layer between the hard, direct bottom rock layer and the grouting layer is expressed in GPa. The moment of inertia of the cross sections of each rock layer between the hard, direct bottom rock layer and the grouting layer, in meters. 4 ; Tensile strength of the hard, direct underlying rock layer, in MPa; The horizontal stress is derived from the lateral support pressure of the roadway, expressed in MPa. The horizontal structural stress is expressed in MPa, perpendicular to the tunnel axis. Thickness of the hard, direct bottom rock layer, in meters; The width of the alleyway is measured in meters (m). The depth of the loosened zone in the sidewall of the tunnel, in meters; This represents the lateral support pressure of the roadway, in MPa.

4. The method for predicting the risk of roadway dynamic damage induced by bottom grouting according to claim 3, characterized in that, Define the critical grouting pressure that causes failure of hard, direct subsurface rock layers. With design grouting pressure The ratio is the roadway dynamic failure safety factor K, which quantitatively assesses the risk of roadway dynamic failure induced by floor grouting; the formula for calculating the roadway dynamic failure safety factor K is as follows: ， In the formula, The critical grouting pressure required to cause damage to the hard, direct underlying rock layer, expressed in MPa; The threshold grouting pressure is preset manually, in MPa.

5. The method for predicting the risk of roadway dynamic damage induced by bottom grouting according to claim 4, characterized in that, Safety factor of roadway dynamic damage The grading criteria are as follows: When the roadway dynamics are disrupted, the safety factor is reduced. When the value is ≤1, the risk of dynamic damage to the roadway induced by bottom grouting is at a high level; When the roadway dynamic failure safety factor is 1 < When the value is ≤1.5, the risk of dynamic damage to the roadway induced by grouting of the floor slab is at a moderate level; When the roadway dynamics are disrupted, the safety factor is reduced. When the value is >1.5, the risk of dynamic damage to the roadway induced by bottom grouting is low. Based on the roadway dynamic damage safety factor, when the risk of roadway dynamic damage induced by floor grouting is low, floor grouting can be carried out normally; when the risk of roadway dynamic damage induced by floor grouting is medium to high, the grouting parameters, such as orifice pressure and grout specific gravity, need to be reconsidered, or grouting modification work can be not carried out.

6. A computer device, characterized in that, It includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the method for predicting the risk of roadway dynamic damage induced by bottom grouting as described in any one of claims 1-5.

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