Collaborative segmented supporting method for matching stiffness of multiple rock stratums of crossing roadway

Abstract

The invention relates to the technical field of mine safety, and provides a cross-layer roadway multi-rock-stratum rigidity matching collaborative segmented supporting method which comprises the steps that plastic zone ranges of different rock stratum areas in a cross-layer roadway are determined, and rock stratum joint fissure zones and weak intercalated layers are identified; monitoring the elastic zone rigidity and the plastic zone weakening rate of the surrounding rock, constructing a surrounding rock mechanical model, obtaining the supporting structure rigidity for inhibiting the expansion of the plastic zone through the surrounding rock mechanical model, and constructing a supporting structure according to the supporting rigidity; and the reinforcing material is sprayed to the surface of the surrounding rock through high-pressure jet flow to form a protective layer. Through the cooperative control thought of weak layer control, rigidity adjustment and resistance transfer, breakthrough transformation of crossing roadway support from passive defense to active control is achieved, according to a scientific surrounding rock mechanical model, the rigidity of the support structure can effectively inhibit expansion of a plastic zone, the stability of a system is maintained, and the stability of the system is improved. And finally, an ultrahigh strength performance and gradient spraying layer structure technology is adopted, so that the compression strength and the shear strength of the surrounding rock are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of mine safety technology, and more specifically, to a collaborative segmented support method for multiple rock strata stiffness matching in cross-layer roadways. Background Technology

[0002] In the construction of tunnels that traverse layers in mines and underground engineering projects, the surrounding rock exhibits severe stiffness heterogeneity due to the need to cross various rock strata with significantly different mechanical properties (such as limestone, sandstone, and mudstone). The stiffness difference between adjacent rock strata can be as great as 5 to 10 times, which leads to a fundamental dilemma for traditional uniform support designs (such as uniformly distributed anchor wire mesh): the stiffness of the support body is seriously mismatched with the stiffness of the surrounding rock, resulting in significant differences in failure modes such as local collapse and roof collapse. In addition, the traditional "one-size-fits-all" support scheme ignores the coupling mechanism between the weakening of the surrounding rock stiffness and the energy release failure, resulting in insufficient or excessive support, which easily leads to instability phenomena such as roof collapse and bulging of the sides. Summary of the Invention

[0003] In view of this, the present invention proposes a collaborative segmented support method for multi-layered roadways with stiffness matching of multiple rock strata. The support method with "controlling weak layers - adjusting stiffness - resisting transmission" as the core actively adapts to changes in the stiffness of the surrounding rock, maximizes the self-supporting capacity of the surrounding rock while controlling deformation, and ensures the long-term stability of the roadway, thereby solving the problems existing in the above-mentioned prior art.

[0004] To achieve the above objectives, this invention proposes a collaborative segmented support method for multi-stratum stiffness matching in cross-strata roadways, comprising:

[0005] Step S1: Determine the range of the plastic zone in different rock strata areas in the cross-layer roadway, identify the joint and fracture zones and weak interlayers in the rock strata, and perform grouting;

[0006] Step S2: Monitor the elastic zone stiffness and plastic zone weakening rate of the surrounding rock, construct a surrounding rock mechanics model, obtain the support structure stiffness that inhibits the expansion of the plastic zone through the surrounding rock mechanics model, and construct the support structure according to the support stiffness.

[0007] Step S3: High-pressure jetting is used to spray the reinforcing material onto the surface of the surrounding rock to form a protective layer.

[0008] Further, step S1 includes: using a high-definition borehole imager to perform a 360° circumferential scan of the cross-layer tunnel to generate a three-dimensional digital model of rock strata joints and fractures; and automatically identifying the boundaries of the plastic zone and the characteristics of weak interlayers through image processing algorithms.

[0009] Furthermore, in step S1, the relationship between the degree of weakening of the surrounding rock stiffness and the range of the plastic zone is constructed to determine the range of the plastic zone, and the stress and radius of the plastic zone after support are obtained.

[0010] Furthermore, the relationship between the degree of weakening of the surrounding rock stiffness and the range of the plastic zone is as follows:

[0011]

[0012] in, For the weakened stiffness, Let r be the initial stiffness of the intact rock mass, and r be the radial distance from the unloading surface of the tunnel excavation. Within the plastic region, This refers to the elastic zone range.

[0013] Furthermore, the stress and radius of the plastic zone after support are expressed by the following formula:

[0014]

[0015] in, For the tangential stress in the plastic zone after support, For the radial stress in the plastic zone after support, p is the radius of the plastic zone after support. i The confining pressure exerted by the support system on the surrounding rock. Let be the internal friction angle, and c be the cohesion within the rock mass. .

[0016] Furthermore, the boundary of the plastic zone is a region with a displacement mutation value ≥3mm / d, and the weak interlayer is characterized by a compressive strength ≤10MPa.

[0017] Furthermore, the construction process of the surrounding rock mechanics model includes:

[0018] Calculate the surrounding rock deformation before and after the intervention of the support structure, and then calculate the deformation shared by the support structure.

[0019] To obtain the relationship between the support stiffness and the support force of the support structure, and then to obtain the relationship between the support stiffness and the range of the plastic zone;

[0020] The weakened stiffness of the plastic zone after support is obtained based on the relationship between support stiffness and plastic zone range;

[0021] The conditions for ensuring the stability of the surrounding rock of the roadway after support are obtained based on the weakened stiffness of the plastic zone after support.

[0022] Furthermore, the relationship between the support stiffness and the support force of the support structure is expressed by the following formula:

[0023]

[0024] Where, p i For support force, k i Indicates the support stiffness, u 总U0 is the total deformation of the surrounding rock after the intervention of the support structure, and u0 is the free deformation of the surrounding rock before the intervention of the support structure.

[0025] Furthermore, the relationship between the support stiffness and the range of the plastic zone is expressed by the following formula:

[0026]

[0027] Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, u 总 U0 represents the total deformation of the surrounding rock after the intervention of the support structure, while u0 represents the free deformation of the surrounding rock before the intervention of the support structure. ρ is the internal friction angle, p0 is the original rock stress, and c is the rock cohesion.

[0028] Furthermore, the condition for satisfying the stability of the surrounding rock of the roadway after the support is expressed by the following formula:

[0029]

[0030] Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, k m The value represents the elastic zone stiffness of the surrounding rock system, k0 represents the initial stiffness of the intact rock mass, and r is the radial distance from the roadway excavation unloading surface.

[0031] Furthermore, in step S3, a 160MPa strength is used to spray reinforcing material according to a gradient spray structure, which not only blocks energy transmission but also reconstructs the stiffness chain of the surrounding rock to form a protective layer.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention achieves a breakthrough transformation in cross-layer roadway support from passive defense to active control through a coordinated control approach of "controlling weak layers → adjusting stiffness → resisting transmission." Specifically, this is reflected in the following aspects:

[0034] 1. The three-dimensional digital model of rock joints and fractures in step S1 of this invention, combined with image processing algorithms, can accurately identify the boundaries of plastic zones and the characteristics of weak interlayers, effectively improving the targeting and efficiency of support, making the support scheme more targeted, and avoiding blind support.

[0035] 2. In step S2 of this invention, fiber optic strain sensors are installed to monitor the stiffness of the elastic zone and the weakening rate of the plastic zone of the surrounding rock. Based on a scientific surrounding rock mechanics model, the stiffness k of the support structure is adjusted. iIt can effectively suppress the expansion of the plastic zone and maintain the stability of the system. Theoretical analysis and actual experiments show that when the support stiffness k... i When the conditions are met, the range R of the plastic zone of the surrounding rock can be defined. pm Effective compression reduces the chance of rockbursts.

[0036] 3. The ultra-high strength (160MPa grade) and gradient sprayed layer structure shotcrete technology used in step 3 of this invention increases the compressive strength (<40MPa) of traditional shotcrete by four times. This not only effectively blocks energy transfer channels but also reconstructs the surrounding rock stiffness chain, meeting the stiffness compensation requirements of step 2 and achieving efficient synergy between support and surrounding rock. In practical applications, this significantly improves the compressive and shear strength of the surrounding rock, extending the service life of the tunnel. Simultaneously, the protective layer formed by this technology also acts as a seal, preventing groundwater erosion and damage to the surrounding rock, further improving the long-term stability of the tunnel. Attached Figure Description

[0037] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings:

[0038] Figure 1 This is a comprehensive framework diagram of the collaborative segmented support method for multi-layered rock strata stiffness matching in cross-layered roadways proposed in this invention.

[0039] Figure 2 This is a schematic diagram illustrating the relationship between the stiffness weakening process and the elastoplastic region in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the interaction between the surrounding rock and the support structure in an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram illustrating the measures taken for construction safety in roadway surrounding rock according to an embodiment of the present invention. Detailed Implementation

[0042] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] This embodiment proposes a collaborative segmented support method for multi-stratum stiffness matching in cross-layer roadways, with a comprehensive framework as follows: Figure 1 As shown, it includes the following steps:

[0044] (1) Step S1: Intelligent positioning of weak layers. The range of plastic zones in different rock strata areas of the cross-layer roadway is determined by the borehole imaging instrument, and the joint and fracture zones and weak interlayers of the rock strata are identified.

[0045] (2) Step S2: Dynamic adaptation of support-surrounding rock stiffness. In the surrounding rock system, when the stiffness k in the elastic zone... m Unable to compensate for stiffness reduction due to weakening in the plastic region (i.e., k) m + f ， When (x) < 0, the system becomes unstable and triggers a rockburst. Therefore, the stiffness k of the support structure is required. i To compensate for the impact of stiffness reduction in the plastic region and maintain system stability.

[0046] (3) Step S3: Blocking the energy transfer channel. High-pressure jet stream is used to spray cement grout and other reinforcing materials onto the surface of the surrounding rock to form a protective layer, which enhances the compressive and shear strength of the surrounding rock and also serves as a seal.

[0047] As a preferred implementation, in step 1, a high-definition borehole imager is used to perform a 360° circumferential scan of the cross-layer tunnel to generate a three-dimensional digital model of rock strata joints and fractures; the boundaries of the plastic zone (areas with displacement mutation values ​​≥3mm / d) and the characteristics of weak interlayers (compressive strength ≤10MPa) are automatically identified through image processing algorithms.

[0048] Using the Weibull statistical damage model, the damage variable D is defined as:

[0049] (1)

[0050] In the formula, r is the radial distance from the roadway excavation unloading surface (0 ≤ r ≤ R). p ); m is the coefficient of non-uniformity of the surrounding rock.

[0051] Assuming the initial stiffness of the intact rock mass is k0, then the equivalent stiffness k in the plastic zone is... p (r) evolves with damage as follows:

[0052] (2)

[0053] Substituting equation (1) into equation (2), we can obtain the weakened stiffness:

[0054] (3)

[0055] In summary, the relationship between the degree of weakening of the surrounding rock stiffness and the extent of the plastic zone can be expressed as:

[0056] (4)

[0057] in, For the weakened stiffness, Let r be the initial stiffness of the intact rock mass, and r be the radial distance from the unloading surface of the tunnel excavation. Within the plastic region, This refers to the elastic zone range.

[0058] Therefore, the elastic region range is (0 ≤ r < R). p ): D ≈ 0, k p ≈ k0; Plastic region range (R) p ≤ r<R e D becomes significant with increasing plastic deformation, and stiffness begins to decrease; the range of the fracture zone (r≥R) e As D→1, the stiffness drops to an extremely low level, close to 0, such as... Figure 2 As shown.

[0059] When the stiffness k of the elastic zone in the surrounding rock system m Unable to compensate for stiffness reduction due to weakening in the plastic region (i.e., k) m When f(x) < 0, the system becomes unstable and triggers a rockburst. Therefore, the stiffness k of the support structure is required. i To compensate for the impact of stiffness reduction in the plastic zone and maintain system stability, the stiffness of the surrounding rock system is corrected after the application of the support structure as follows:

[0060] (5)

[0061] Where f(x) < 0 represents the weakening stiffness in the plastic zone, and the support objective is to satisfy the stability of the surrounding rock of the roadway, which requires kl > 0, i.e.:

[0062] (6)

[0063] Therefore, the interaction between the surrounding rock and the support structure is crucial during tunnel excavation. From a physical perspective, deformation coordination involves stress transfer and stiffness matching. Stress transfer refers to the transmission of residual stress from the surrounding rock to the support structure through the contact surface, thereby achieving stress redistribution.

[0064] When the support system applies confining pressure p to the surrounding rock i At that time, it participated in the elastoplastic deformation process of the rock mass, through a simplified model ( Figure 3 The interaction between the surrounding rock and the support system in the tunnel is described by ( ), and the tangential and radial stresses in the plastic zone under the action of the support structure are respectively marked. and The corresponding stress in the elastic region is and ,also, and These represent the radii of the plastic zone and the elastic zone after support, respectively.

[0065] The expressions for stress and radius in the plastic zone after support can be rewritten as:

[0066] (7)

[0067] in, For the tangential stress in the plastic zone after support, For the radial stress in the plastic zone after support, p is the radius of the plastic zone after support. i The confining pressure exerted by the support system on the surrounding rock. Let be the internal friction angle, and c be the cohesion within the rock mass. .

[0068] In a preferred embodiment, in step 2, fiber optic strain sensors are installed to monitor the stiffness of the elastic zone and the weakening rate of the plastic zone of the surrounding rock. Before the roadway is excavated to the point of support, the surrounding rock undergoes free deformation under the action of in-situ stress, with a deformation amount of u0. After the support structure is introduced, the surrounding rock and the support structure deform together until they reach an equilibrium state, at which point the total deformation amount is u. 总 Then the deformation shared by the support structure is:

[0069] (8)

[0070] If the deformation of the support structure is u i Then the surrounding rock and the support structure should meet the deformation coordination requirement, that is:

[0071] (9)

[0072] Support stiffness k i It refers to the ability of the support structure to resist deformation of the surrounding rock and inhibit the expansion of the plastic zone. This is related to the support force p. i The relationship can be expressed as:

[0073] (10)

[0074] Where, p i For support force, k i Indicates the support stiffness, u 总 U0 is the total deformation of the surrounding rock after the intervention of the support structure, and u0 is the free deformation of the surrounding rock before the intervention of the support structure.

[0075] Substituting formula (10) into formula (7), we can obtain the relationship between support stiffness and plastic zone range:

[0076] (11)

[0077] Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, u 总 U0 represents the total deformation of the surrounding rock after the intervention of the support structure, while u0 represents the free deformation of the surrounding rock before the intervention of the support structure. ρ is the internal friction angle, p0 is the original rock stress, and c is the rock cohesion.

[0078] Through the analysis of the relationship between the weakening of the surrounding rock stiffness and the plastic expansion in the above steps, it can be seen that substituting equation (11) into equation (4) yields the weakened stiffness k in the plastic zone after support. p (r):

[0079] (12)

[0080] Substituting equation (12) into equation (6), we can obtain the conditions for satisfying the stability of the surrounding rock of the roadway after the support structure is applied:

[0081] (13)

[0082] Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, k m The value represents the elastic zone stiffness of the surrounding rock system, k0 represents the initial stiffness of the intact rock mass, and r is the radial distance from the roadway excavation unloading surface.

[0083] From formula (13), it can be seen that the support stiffness k i Rock mass strength parameters (c) The plastic zone range R is jointly dominated by the original rock stress p0 and the stress of the original rock. pm ′ With regard to the stability of the surrounding rock.

[0084] 1) Support stiffness k i By suppressing deformation u i And to increase the overall stiffness of the surrounding rock system, directly compressing the plastic zone range R pm ′ And slow down the rate of stiffness reduction;

[0085] 2) Rock mass cohesion c and internal friction angle By enhancing the self-supporting capacity of the rock mass, the dependence of the plastic zone on support is reduced, especially in high-density rock formations. The value can also weaken the stress gradient and the exponential effect, further suppressing the sensitivity to plastic zone expansion;

[0086] 3) The increase in the original rock stress p0 needs to be offset by high-rigidity support or stress relief holes to counteract the driving effect of its expansion plastic zone.

[0087] As a preferred implementation, in step 3, ultra-high strength performance (160MPa level) and gradient spray layer structure are used to achieve a 4-fold increase in the compressive strength of traditional sprayed concrete (<40MPa), which not only blocks energy transmission but also reconstructs the stiffness chain of the surrounding rock, thus fully meeting the stiffness compensation requirements of step 2.

[0088] In summary, such as Figure 4 As shown, this embodiment adopts the following innovative measures for construction safety in the surrounding rock of the tunnel:

[0089] (1) Controlling weak layers: Identify the relatively weak layers in the surrounding rock, such as weak rock layers, joint and fissure development zones, etc., and use grouting reinforcement technology to inject cement grout, resin materials, etc. into the weak layers to fill the fissures, form a reinforced body, improve the density and strength of the weak layers, and enhance the stability of the roof.

[0090] (2) Adjusting stiffness: When the stiffness of the surrounding rock system is lower than that of the local rock mass in the roadway (km < ks), the surrounding rock is prone to deformation and failure. The support structure should focus on improving the overall stiffness and bearing capacity of the surrounding rock, reducing the stiffness difference with the surrounding rock system, and controlling deformation and energy release to ensure uniform and coordinated deformation of the surrounding rock. For example, high-strength anchor bolts (cables) can be used for support. Through prestressed active support, the self-bearing capacity of the surrounding rock can be enhanced. Secondly, grouting reinforcement can significantly improve the mechanical properties of the surrounding rock, enhance its resistance to deformation, increase the stiffness and strength of the surrounding rock, and reduce energy release.

[0091] (3) Blocking transmission: Blocking the connection between the surrounding rock and the external environment to prevent weathering or water erosion of the surrounding rock. High-pressure jetting is used to spray cement slurry and other reinforcing materials onto the surface of the surrounding rock to form a protective layer, which enhances the compressive and shear strength of the surrounding rock and also acts as a seal. When the surrounding rock is subjected to pressure and deformation, the shotcrete layer, as a whole, can provide a certain reaction force, limit the excessive deformation of the surrounding rock, redistribute the stress inside the surrounding rock, reduce stress concentration, and thus prevent the transmission of destructive energy inside the surrounding rock.

[0092] Example 2

[0093] This embodiment provides a specific implementation method for grouting in step S1 of embodiment one, including the following steps:

[0094] Step 1: Grouting is carried out in the plastic zone and weak interlayer of the roadway. First, drilling is performed: according to the diameter and length of the anchor cable, a φ36mm drill bit is selected for drilling.

[0095] Step 2: Anchoring: Install 28mm diameter anchoring agent, first inserting the thrust tube (white rigid tube) and then the sealing tube (black flexible tube) in sequence, and stir the anchoring agent;

[0096] Step 3: Tensioning: Install anchor cable trays, ball pads, locks, etc., and tension the anchor cables. During the tensioning process, the sealing tube is compressed and then expands to achieve automatic sealing.

[0097] Step 4: Grouting: Install the special grouting joint for anchor cables and begin grouting.

[0098] Example 3

[0099] This embodiment provides a specific implementation method for the construction of the support structure in step S2 of embodiment one, including the following steps:

[0100] Step 1: The support steel pipe is a 194mm×10mm seamless steel pipe, the core concrete is PO52.5 ordinary Portland cement, the coarse aggregate is crushed stone with a maximum particle size of 15mm, the fine aggregate is river sand, and 2% expansion agent is added.

[0101] Step 2: Determine the centerline and waistline of the tunnel. Following the direction and slope indicated by the centerline and waistline, gradually expand and smear the tunnel from one side to the other. During the expansion and smearing process, follow the principle of top to bottom, first clearing the rocks near the tunnel roof, then expanding and smearing the two sides, and finally expanding and smearing the floor.

[0102] Step 3: Assemble the steel pipe frame at a suitable location on the tunnel floor, paying attention to its flatness and verticality during assembly. Then, gradually erect the assembled steel pipe frame and use temporary supports to secure its position, ensuring it is flush against the surrounding rock of the tunnel. Connect the steel pipe frame to the surrounding rock anchors (such as anchor bolts or anchor cables) using bolts or cable clamps to form a unified support structure.

[0103] Example 4

[0104] This embodiment provides a specific method for implementing shotcrete in step S3 of Embodiment 1, including the following steps:

[0105] Step 1: Before shotcreting, the cross-sectional dimensions of the tunnel should be checked, loose and dangerous rocks should be removed, and serious under-excavation or over-excavation should be dealt with.

[0106] Step 2: Depending on the rock quality, use high-pressure air to clean the sprayed surface of the tunnel. Arrange the steel mesh frame structure according to the spraying location.

[0107] Step 3: Check the preparation of materials such as shotcrete material, fiber, and additives, and adjust the working status of air compressor, spraying and other mechanical equipment.

[0108] Step 4: After the preparation for the spraying operation is completed, strictly control the specified dosage of quick-setting agent and add it evenly. During spraying, strictly control the water-cement ratio to ensure that the sprayed surface is flat and smooth, without dry spots or slippage.

[0109] Step 5: To ensure the full hydration of the shotcrete material, uniform strength growth of the shotcrete, reduce concrete shrinkage and cracking, and ensure the quality of the shotcrete, good curing is required after shotcreting. The ventilation rate in the well should be controlled 1-2 hours after final setting, and the curing time should not be less than 3 days. After the shotcrete has set, water spraying should be carried out every 6 hours, and the surface condition should be observed.

[0110] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A collaborative segmented support method for multi-layered rock strata stiffness matching in cross-layered roadways, characterized in that, include: Step S1: Determine the range of the plastic zone in different rock strata areas in the cross-layer roadway, identify the joint and fracture zones and weak interlayers in the rock strata, and perform grouting; Step S2: Monitor the elastic zone stiffness and plastic zone weakening rate of the surrounding rock, construct a surrounding rock mechanics model, obtain the support structure stiffness that inhibits the expansion of the plastic zone through the surrounding rock mechanics model, and construct the support structure according to the support stiffness. Step S3: High-pressure jetting is used to spray the reinforcing material onto the surface of the surrounding rock to form a protective layer.

2. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 1, characterized in that, Step S1 includes: using a high-definition borehole imager to perform a 360° circumferential scan of the cross-layer tunnel to generate a three-dimensional digital model of rock strata joints and fractures; and automatically identifying the boundaries of the plastic zone and the characteristics of weak interlayers through image processing algorithms.

3. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 1, characterized in that, In step S1, the relationship between the degree of weakening of the surrounding rock stiffness and the range of the plastic zone is established to determine the range of the plastic zone, and the stress and radius of the plastic zone after support are obtained.

4. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 3, characterized in that, The relationship between the degree of weakening of the surrounding rock stiffness and the extent of the plastic zone is shown below: ， in, For the weakened stiffness, Let r be the initial stiffness of the intact rock mass, and r be the radial distance from the unloading surface of the tunnel excavation. Within the plastic region, This refers to the elastic zone range; The stress and radius of the plastic zone after support are expressed by the following formula: ， in, For the tangential stress in the plastic zone after support, For the radial stress in the plastic zone after support, p is the radius of the plastic zone after support. i The confining pressure exerted by the support system on the surrounding rock. Let be the internal friction angle, and c be the cohesion within the rock mass. .

5. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 2, characterized in that, The boundary of the plastic zone is a region with a displacement abrupt change value ≥3mm / d, and the weak interlayer is characterized by a compressive strength ≤10MPa.

6. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 1, characterized in that, The process of constructing the surrounding rock mechanics model includes: Calculate the surrounding rock deformation before and after the intervention of the support structure, and then calculate the deformation shared by the support structure. To obtain the relationship between the support stiffness and the support force of the support structure, and then to obtain the relationship between the support stiffness and the range of the plastic zone; The weakened stiffness of the plastic zone after support is obtained based on the relationship between support stiffness and plastic zone range; The conditions for ensuring the stability of the surrounding rock of the roadway after support are obtained based on the weakened stiffness of the plastic zone after support.

7. The method for coordinated segmented support of multi-stratum stiffness matching in cross-layer roadways according to claim 6, characterized in that, The relationship between the support stiffness and support force of the support structure is expressed by the following formula: ， Where, p i For support force, k i Indicates the support stiffness, u 总 U0 is the total deformation of the surrounding rock after the intervention of the support structure, and u0 is the free deformation of the surrounding rock before the intervention of the support structure.

8. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 6, characterized in that, The relationship between the support stiffness and the range of the plastic zone is expressed by the following formula: ， Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, u 总 U0 represents the total deformation of the surrounding rock after the intervention of the support structure, while u0 represents the free deformation of the surrounding rock before the intervention of the support structure. ρ is the internal friction angle, p0 is the original rock stress, and c is the rock cohesion.

9. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 6, characterized in that, The condition for ensuring the stability of the surrounding rock of the roadway after support is expressed by the following formula: ， Where, k i R represents the support stiffness. pm ′ Indicates the range of the plastic region, k m The value represents the elastic zone stiffness of the surrounding rock system, k0 represents the initial stiffness of the intact rock mass, and r is the radial distance from the roadway excavation unloading surface.

10. The method for coordinated segmented support of multiple rock strata with stiffness matching in cross-layer roadways according to claim 1, characterized in that, Step S3 uses a 160MPa strength to spray reinforcement material according to a gradient spray structure, which not only blocks energy transmission but also reconstructs the stiffness chain of the surrounding rock to form a protective layer.

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