A pre-compensation micro-arched roadway structure and an effective section maintaining method thereof

Abstract

The application discloses a pre-compensation micro-arched side help roadway structure and an effective section maintaining method thereof, which comprises a roof, a floor and pre-compensation micro-arched side helps; the roof, the floor and the pre-compensation micro-arched side helps on both sides form a closed roadway section; a roadway design effective section is arranged in the roadway, and preset clearance control lines are arranged on the left and right sides of the roadway design effective section; the initial excavation profiles of the pre-compensation micro-arched side helps on both sides are outwardly convex, and are arranged on the outside of the corresponding preset clearance control lines; supporting members are arranged on the surfaces of the roof and the pre-compensation micro-arched side helps, and the supporting members are any one or more of an anchor rod, an anchor cable and a steel strand. According to the pre-compensation micro-arched side help which is outwardly convex and is designed according to the predicted convergence of the roadway sides before tunneling and forming, the roadway sides converge and approach the preset clearance control lines after the roadway is in service, and the effective section of the roadway can be maintained.

Description

Technical Field

[0001] This invention relates to a pre-compensated micro-arch sidewall roadway structure and its effective cross-section preservation method, belonging to the field of coal mine underground roadway surrounding rock control technology. Background Technology

[0002] As coal mining depth increases, the surrounding rock of roadways is affected by multiple factors, including high ground stress, mining disturbance, rheology of weak coal and rock, development of joints and fissures, and floor deformation. Currently, commonly used rectangular, trapezoidal, and straight-walled semi-circular arch roadways in coal mines are prone to various instability problems during long-term service, such as roof subsidence, bulging of the sidewalls, coal wall spalling, and floor heave. For core roadways that serve as underground material transport, ventilation, personnel passage, and the layout and passage of fully mechanized mining equipment, the inward convergence deformation of the sidewalls is a major challenge restricting roadway performance. This deformation compresses ventilation space, equipment layout space, and safety margins, resulting in a continuous reduction in the effective cross-section of the roadway. Furthermore, to ensure normal roadway use, subsequent repair work such as sidewall widening, floor leveling, and reinforcement is required, increasing the amount of underground construction work and mining costs.

[0003] Currently, the control of surrounding rock deformation in deep tunnels in my country mainly focuses on support methods that improve support strength and enhance the overall integrity of the surrounding rock. For example, patent CN117552813B discloses a construction method for reinforcing the surrounding rock in deep tunnels; patent CN112196596B proposes an advanced support scheme using a grouting anchor cable combination beam adapted to fractured surrounding rock; and patent CN114165269B discloses a composite tunnel support system based on a combination of steel-concrete composite supports and shotcrete technology. All of these existing technologies enhance the overall integrity of the surrounding rock and the load-bearing capacity of the support structure through anchor bolts, anchor cables, grouting reinforcement, shotcrete, steel supports, and their combined support structures, thereby resisting surrounding rock deformation. However, this type of support mode is a passive anti-deformation support, which can only constrain the displacement of the surrounding rock from the outside. It does not eliminate the inherent inward squeezing deformation defects of the sidewalls of straight-walled roadways from the perspective of the roadway cross-sectional structure. Under complex working conditions such as deep high ground stress, soft rock rheology and repeated mining disturbance, the problem of inward squeezing deformation of the two sides cannot be solved from the root. The deformation will still gradually invade the pre-designed cross-section of the roadway, eventually causing engineering problems such as insufficient roadway net width, failure of effective cross-section, and high frequency of repairs.

[0004] To address this issue, some existing technologies control the deformation of the surrounding rock in roadways by reserving deformation allowances. For example, patent CN105180888B determines the reserved deformation allowances for the tunnel arch and sidewalls through test section excavation and monitoring of arch settlement and horizontal clearance convergence; patent CN106014423B discloses an excavation and support method for close-range coal seam roadways, which adapts to later-stage deformation of the surrounding rock by determining the reserved excavation allowances for the two sides of the close-range coal seam roadway; patent CN1083896A discloses a roadway support method for underground goaf excavation in coal mines, proposing reserved deformation allowances for excavation and implementing combined anchor bolt support for the roof and sidewalls; and patent CN101280684A discloses a method for supporting the surrounding rock of roadways left in goaf areas under three-soft geological conditions, which ensures the usable cross-section of the primary roadway by expanding the cross-section of the roadway and reserving roof and sidewall deformation allowances. While the above scheme compensates for the shortcomings of purely passive support and considers the impact of later-stage deformation of the surrounding rock on the usable cross-section of the roadway, the technical solution still has limitations: its core logic is to broadly widen and raise the roadway excavation cross-section, which is a passive reservation mode of full-area expansion. On the one hand, it will increase the amount of earth and rock excavated in the roadway and the cost of support materials, increasing the difficulty of construction; on the other hand, it does not combine the actual convergence data of the roadway's single side to design the sidewall cross-section structure in a targeted manner, nor does it establish a matching relationship between the standardized clearance control boundary and the final state of sidewall deformation, thus failing to achieve pre-compensation for deformation.

[0005] In summary, none of the existing mainstream technical solutions can offset the internal squeezing deformation of the two sides from a structural perspective and solve the problem of easy failure of the effective cross section of deep roadways while controlling the increase in tunneling volume and support costs. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a pre-compensated micro-arched sidewall roadway structure and a method for maintaining its effective cross-section. Based on the expected convergence of the two sides of the roadway, the two sides are designed as outwardly protruding pre-compensated micro-arched sidewalls before excavation, so that the two sides converge and approach the preset clearance control line after the roadway is put into service, which is beneficial to maintaining the effective cross-section of the roadway.

[0007] To achieve the above objectives, this invention employs a pre-compensated micro-arched sidewall roadway structure, comprising a roof plate, a floor plate, and two symmetrically arranged pre-compensated micro-arched sidewalls. The roof plate, floor plate, and the two pre-compensated micro-arched sidewalls together form a closed roadway cross-section. An effective design cross-section for defining the roadway's service limit boundary is provided inside the roadway, with vertical preset clearance control lines set on both sides of the effective design cross-section. The initial excavation contours of the two pre-compensated micro-arched sidewalls protrude outwards and are arranged outside the corresponding preset clearance control lines to pre-compensate for the inward squeezing deformation of the two sidewalls during the roadway's service life. Support components are evenly distributed on the surfaces of the roof plate and the pre-compensated micro-arched sidewalls, and these support components are any one or more of anchor bolts, anchor cables, and steel strands. The pre-compensated micro-arched sidewalls can converge inwards in a controlled manner under the influence of surrounding rock pressure and mining disturbance, and the final convergence contour does not intrude into the inside of the preset clearance control lines, maintaining the roadway's effective design cross-section unchanged.

[0008] A second aspect of the present invention also provides a method for maintaining the effective cross-section of a pre-compensated micro-arched roadway, applied to the aforementioned pre-compensated micro-arched roadway structure, comprising the following steps:

[0009] S1. Collect the basic engineering parameters of the roadway to be excavated and the adjacent roadways that have already been excavated, and obtain the side convergence monitoring data of the adjacent roadways or the test section roadway.

[0010] S2. Based on the needs of roadway ventilation, transportation, equipment access and personnel operation, determine the effective cross-section of the roadway design, and lay out two mutually parallel preset clearance control lines on the left and right sides of the effective cross-section of the roadway design.

[0011] S3. Based on the engineering basic parameters and the sidewall convergence monitoring data, predict the maximum inward convergence of the two sides of the roadway to be excavated during the entire service life, calculate the corresponding outward convexity compensation amount, and complete the contour parameter design of the pre-compensated micro-arch sidewall based on the outward convexity compensation amount.

[0012] S4. Cut and excavate the tunnel to be excavated according to the design outline to form a closed tunnel section consisting of the roof, floor and double-sided pre-compensated micro-arched sidewalls.

[0013] S5. Support components are installed on the roof and the pre-compensated micro-arched sidewalls on both sides of the roadway. The support components are anchor bolts, anchor cables or steel strands to constrain the disorderly abrupt deformation of the pre-compensated micro-arched sidewalls and make the sidewall convergence process controllable.

[0014] S6. During the service phase of the roadway, real-time monitoring of the convergence deformation data of the pre-compensated micro-arched sidewalls is conducted to control the inward deformation of the pre-compensated micro-arched sidewalls. After deformation, the sidewall profile gradually approaches the preset clearance control line to maintain the effective cross-section of the roadway design.

[0015] As a further step, in step S1, the basic engineering parameters include the effective cross-section of the tunnel design, the effective net width of the tunnel design, the effective net height of the tunnel design, the physical and mechanical parameters of the surrounding rock, and the original rock stress and mining stress parameters.

[0016] The surrounding rock physical and mechanical parameters include the uniaxial compressive strength, tensile strength, cohesion, internal friction angle, elastic modulus, Poisson's ratio, softening coefficient, and joint and fracture development characteristics of the coal and rock mass.

[0017] The original rock stress and mining stress parameters include vertical ground stress, maximum horizontal principal stress, minimum horizontal principal stress, mining influence coefficient, and roadway depth.

[0018] The sidewall convergence monitoring data is a dataset of the displacement of the left and right sides of the roadway over time.

[0019] As a further step, in step S2, both of the preset clearance control lines are vertical straight lines, and the distance between the two preset clearance control lines is equal to the effective net width of the roadway corresponding to the effective cross-section of the roadway design.

[0020] The initial excavation profile of the pre-compensated micro-arched sidewall is located outside the preset clearance control line. The final profile of the pre-compensated micro-arched sidewall after controlled convergence is in line with the preset clearance control line or maintains a safe distance from the preset clearance control line.

[0021] As a further step, in step S3, the calculation formula for the maximum outward arch height 'a' of the pre-compensated micro-arched sidewall is as follows: ;

[0022] Among them, a σ The arch height is controlled by theoretical stress; a u To compensate for the arch height due to deformation, a u It is used to compensate for the inward convergence deformation of the pre-compensated micro-arch sidewall caused by the rheology of the surrounding rock and mining disturbance in the later stage.

[0023] As a further step, the theoretical stress controls the arch height a σ The calculation method is as follows: ;

[0024] Where, η σ The theoretical arch height ratio is calculated using the following formula: B represents the effective net width of the tunnel design; σ n For the normal stress concentration on the sidewall of the roadway, σ c It represents the shear strength of the coal and rock mass.

[0025] As a further step, the deformation compensation arch height a u The calculation formula is: ;

[0026] In the formula, u is the corrected maximum inward convergence of a single rock face, λ is the surrounding rock deformation correction coefficient, and Δ is the safety compensation amount.

[0027] The formula for calculating u is: ;

[0028] In the formula, u0 is the basic value of maximum inward convergence of a single side, and k m k is the correction factor for on-site monitoring. s The support constraint correction coefficient; the on-site monitoring correction coefficient k m This is used to correct for parameter differences between the roadway to be excavated and adjacent roadways in terms of burial depth, original rock stress, mining intensity, coal and rock mechanical properties, and degree of fracture development; the support constraint correction coefficient k s It is used to characterize the ability of support components composed of anchor bolts, anchor cables and steel strands to suppress the inward convergence deformation of pre-compensated micro-arched sidewalls;

[0029] When the geological conditions, stress conditions, and support parameters of the tunnel to be excavated are consistent with those of the adjacent tunnels, k m k s The value approaches 1;

[0030] When the disturbance during mining in the roadway to be excavated is stronger than that in adjacent roadways, and the surrounding rock is weaker than that in adjacent roadways, k m The value is greater than 1;

[0031] When the support strength of the roadway to be excavated is higher than that of the adjacent roadway, k s The value is less than 1.

[0032] As a further step, the engineering economics of the maximum outward arch height 'a' are checked, and the ratio of the maximum outward arch height 'a' to the effective net width B of the roadway is controlled to be within the range of 5% to 15%.

[0033] If the calculated maximum outward arch height 'a' exceeds the preset range, it can be jointly controlled by any one or more methods, such as strengthening the support strength of anchor bolts and anchor cables, adding side support components, grouting and reinforcing the surrounding rock, assembling pressure relief components, and adjusting the outward arch height of the double-sided pre-compensated micro-arch sidewalls.

[0034] As a further step, in step S3, the pre-compensated micro-arched sidewall adopts an arc structure, and the arc radius R is calculated using the following formula: ;

[0035] In the formula, H b To pre-compensate the effective vertical height between the top and bottom plates corresponding to the micro-arched sidewall, 'a' represents the maximum outward arch height of the pre-compensated micro-arched sidewall.

[0036] As a further step, in step S4, the connection between the pre-compensated micro-arched sidewall and the top and bottom plates adopts a rounded transition or a short straight section transition structure to weaken the stress concentration effect at the corners of the roadway; for tunneling equipment that does not have the conditions for direct arc cutting, the roadway cross-section forming operation is completed by using a multi-segment broken line fitting arc contour.

[0037] And / or, in step S6, the criteria for determining the effective cross-section of the roadway are: during the service period, the deformed profile of the pre-compensated micro-arched sidewall is located outside the preset clearance control line or coincides with the preset clearance control line, and the real-time net width and real-time cross-sectional area of ​​the roadway are not less than the designed effective net width and the designed effective cross-sectional area of ​​the roadway, respectively; convergence measurement stations and three-dimensional laser scanners are used to collect the convergence deformation data of the pre-compensated micro-arched sidewall. When the convergence deformation is close to the warning threshold, the roadway reinforcement and support are completed by adding anchor bolts, anchor cables, secondary grouting, and shotcreting reinforcement.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] (1) The present invention designs the two sides of the roadway as pre-compensated micro-arched sidewalls located outside the preset clearance control line, so that the deformation space of the two sides inward convergence in the later stage is arranged outside the design effective cross section in advance, which can avoid the deformation of the two sides intruding into the design effective cross section and maintain the effective net width and effective cross section area of ​​the roadway.

[0040] (2) This invention does not simply widen or raise the roadway cross section, nor does it adopt a common circular or integral arch cross section. Instead, it determines the outward convexity compensation amount based on the expected inward convergence amount of the two sides of the roadway, so as to achieve pre-compensation control of the deformation of the two sides without significantly increasing the amount of tunneling work.

[0041] (3) The present invention combines the pre-compensated micro-arched sidewall with anchor bolts, anchor cables or steel strand support components, so that the sidewall is controlled to converge inward under the action of surrounding rock pressure and approach the preset clearance control line, which is conducive to reducing the amount of subsequent expansion, bottoming and repair work, and improving the long-term service stability of the roadway. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the pre-compensated micro-arch side roadway of the present invention;

[0043] Figure 2 The following are comparison diagrams showing the deformation effects of the pre-compensated micro-arched sidewalls of the present invention and the traditional roadway cross-section: (a) before deformation of the pre-compensated micro-arched sidewalls, (b) after deformation of the pre-compensated micro-arched sidewalls, and (c) after deformation of the traditional roadway cross-section.

[0044] Figure 3 This is a schematic diagram of the geometric parameters of the pre-compensated micro-arched sidewall of the present invention.

[0045] In the figure: 1. Pre-compensated micro-arched sidewall; 2. Pre-set clearance control line; 3. Roof plate; 4. Floor plate; 5. Anchor bolt; 6. Anchor cable; 7. Effective cross-section of the roadway design; 8. Sidewall outline after deformation; 9. Outline of the traditional cross-section after deformation; 10. Roadway to be excavated. Detailed Implementation

[0046] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0047] Example 1

[0048] This embodiment provides a pre-compensated micro-arch side roadway structure, which is suitable for underground mining roadways in coal mines. The effective net width B of the roadway design is 5500mm.

[0049] like Figure 1 , Figure 2 As shown, the tunnel structure includes a roof slab 3, a floor slab 4, and two sets of symmetrically arranged pre-compensated micro-arched sidewalls 1. The roof slab 3, the floor slab 4, and the two pre-compensated micro-arched sidewalls 1 together form a closed tunnel cross-section. The area inside the tunnel that defines the standard usable space is the tunnel design effective cross-section 7. Two parallel vertical preset clearance control lines 2 are set on the left and right sides of the tunnel design effective cross-section 7, and the distance between the two preset clearance control lines 2 is equal to the tunnel design effective net width of 5500mm.

[0050] The pre-compensated micro-arched sidewall 1 protrudes outwards as a whole, and its initial outline after excavation is entirely located outside the corresponding preset clearance control line 2. Support components, namely anchor bolts 5 and anchor cables 6, are evenly distributed on the surface of the roof slab 3 and the pre-compensated micro-arched sidewall 1 to constrain the disorderly deformation of the pre-compensated micro-arched sidewall 1. During the service of the roadway, the pre-compensated micro-arched sidewall 1 slowly and controllably converges inwards under the pressure of the surrounding rock. The deformed sidewall outline 8 formed after convergence will not intrude into the inner side of the preset clearance control line 2. Compared with the deformed outline 9 of the traditional cross-section that occupies the usable space, this ensures the standard usable cross-sectional dimensions of the roadway.

[0051] Example 2

[0052] A method for maintaining the effective cross-section of a pre-compensated micro-arched roadway, applied to the aforementioned pre-compensated micro-arched roadway structure, includes the following steps:

[0053] S1. Collect the basic engineering parameters of the roadway to be excavated 10 and the adjacent roadways that have been excavated, and obtain the side convergence monitoring data of the adjacent roadways or the test section roadway.

[0054] Specifically, in this embodiment, the roadway 10 to be excavated is a mining roadway, and the original design effective net width B of the roadway is 5500mm; based on the requirements of roadway transportation, ventilation, pedestrians, equipment installation, pipeline hanging and safety clearance, the design effective cross section 7 and the design effective net width B of the roadway are determined.

[0055] The basic engineering parameters include the effective cross-section of the tunnel (7), the effective net width of the tunnel (B), the effective net height of the tunnel, the physical and mechanical parameters of the surrounding rock, and the original rock stress and mining stress parameters.

[0056] The surrounding rock physical and mechanical parameters include the uniaxial compressive strength, tensile strength, cohesion, internal friction angle, elastic modulus, Poisson's ratio, softening coefficient, and joint and fracture development characteristics of the coal and rock mass.

[0057] The original rock stress and mining stress parameters include vertical ground stress, maximum horizontal principal stress, minimum horizontal principal stress, mining influence coefficient, and tunnel depth.

[0058] The physical and mechanical parameters of the surrounding rock can be obtained through in-situ core sampling and laboratory uniaxial compression, triaxial compression, Brazilian splitting and shear tests; the geostress parameters can be obtained through hydraulic fracturing, stress relief, borehole deformation gauge or mine pressure inversion.

[0059] The side convergence monitoring data can be obtained from adjacent excavated roadways or test roadways, including data on the displacement of the left and right sides over time.

[0060] In this embodiment, based on the 30-day monitoring results of adjacent roadways, the maximum inward convergence base value u0 of a single sidewall is 260mm.

[0061] S2. Determine the preset clearance control line 2 on both sides of the effective cross section 7 of the roadway design. The preset clearance control line 2 serves as the boundary for maintaining the effective cross section after the roadway is put into service, and determines the control target for the inward convergence of the two sides of the roadway.

[0062] Specifically, based on the requirements for roadway transportation, ventilation, pedestrians, equipment installation, pipeline hanging, and safety clearance, the effective design cross-section 7 of the roadway is first determined; the straight side boundary on both sides of the effective design cross-section 7 of the roadway is the preset clearance control line 2, and the distance between the two preset clearance control lines 2 is the effective design width B of the roadway, which is 5500mm;

[0063] like Figure 1 As shown, the pre-compensated micro-arched sidewall 1 is located outside the preset clearance control line 2 during the excavation and forming process. The preset clearance control line 2 is used to define the final state boundary of the two sides after the roadway is in service. That is, during the service of the roadway, the pre-compensated micro-arched sidewall 1 can converge in a controlled manner to the inside of the roadway under the action of the surrounding rock pressure, but its converged contour should not invade the inside of the preset clearance control line 2, so as to ensure that the effective cross-section of the roadway is not occupied by the deformation of the two sides.

[0064] S3. Based on the engineering basic parameters and the side convergence monitoring data, determine the expected inward convergence amount and the corresponding outward convexity compensation amount of the two sides during the service period, and design the two sides of the roadway as pre-compensated micro-arched side sides 1 located outside the preset clearance control line 2.

[0065] Specifically, the maximum outward arch height 'a' of the pre-compensated micro-arched sidewall 1 is controlled according to the theoretical stress. σ and deformation compensation arch height a u The formula for its calculation is jointly determined as follows:

[0066] ;

[0067] In the formula, 'a' represents the maximum outward arch height of the pre-compensated micro-arched sidewall 1, which is the maximum distance the pre-compensated micro-arched sidewall 1 protrudes outward from the preset clearance control line 2 relative to the roadway; σ The arch height is controlled by theoretical stress to meet the sidewall stress control requirements; a u The arch height is used to compensate for deformation and meet the requirements for subsequent convergence deformation compensation; the maximum outward convex arch height 'a' is not less than 'a'. σ With a u The larger of the two;

[0068] Theoretical stress controls the arch height a σ The calculation formula is:

[0069] ;

[0070] Theoretical arch height ratio η σ The calculation formula is:

[0071] ;

[0072] In the formula, B is the effective net width of the tunnel design, and η σ For the theoretical arch height ratio, σ n For the normal stress concentration on the sidewall of the roadway, σ c The shear strength of the coal and rock mass is given by this formula. This formula is used to determine the basic arch height required for the outwardly convex micro-arch sidewall based on the stress state of the roadway sidewall, so that the pre-compensated micro-arch sidewall 1 can improve the stress concentration state of the sidewall.

[0073] Deformation compensation arch height a u The calculation formula is:

[0074] ;

[0075] The revised formula for calculating the maximum inward convergence u of a single-sided approach is as follows:

[0076] ;

[0077] In the formula, u is the corrected maximum inward convergence of a single sidewall, λ is the surrounding rock deformation correction coefficient, Δ is the safety compensation amount, u0 is the basic value of the maximum inward convergence of a single sidewall obtained from adjacent roadways, test roadways, or numerical simulation, and k m k is the correction factor for on-site monitoring. s This is the correction factor for support constraints;

[0078] Where, k m Used to correct differences between the roadway to be excavated 10 and adjacent roadways in terms of burial depth, original rock stress, degree of mining impact, coal and rock strength, and degree of joint and fracture development; k s This is used to reflect the restraining effect of anchor bolts, anchor cables, or steel strand support components on the convergence deformation of the sidewall. When the geological conditions, stress conditions, and support parameters of the roadway 10 to be excavated are basically the same as those of the adjacent roadways, k m and k s A value close to 1 is acceptable; however, when the impact of mining on the 10th tunnel to be excavated is stronger, the surrounding rock is weaker, or the service time is longer, k should be used. m It can be greater than 1; when the support strength is higher than that of adjacent roadways, k s It can be less than 1;

[0079] In this embodiment, the roadway 10 to be excavated is a mining roadway with a designed effective net width B of 5500 mm. Based on the 30-day monitoring results of adjacent roadways, the maximum inward convergence base value u0 of the single side is obtained as 260 mm. Considering the roadway burial depth, original rock stress, degree of mining impact, coal and rock strength, and degree of joint and fracture development, u0 is corrected by on-site monitoring and support constraints to obtain the corrected maximum inward convergence amount u of the single side. Considering soft coal, mining disturbance, and construction errors, the surrounding rock deformation correction coefficient λ is taken as 1.15, the safety compensation amount Δ is 40 mm, and the arch height a is controlled by theoretical stress. σ A comprehensive verification was conducted to determine the maximum outward arch height 'a' of the pre-compensated micro-arched sidewall 1.

[0080] If theoretical stress controls the arch height a σ Not greater than the deformation compensation arch height a u Then, the maximum outward convex arch height 'a' is determined according to the deformation compensation arch height. At this time, 'a'... u =1.15×260mm+40mm=339mm, that is, the maximum outward arch height a is taken as 339mm; if the theoretical stress controls the arch height a σ If the diameter is greater than 339mm, then the maximum height of the outward convex arch 'a' is determined by a. σ Sure.

[0081] To avoid excessive outward convexity of the pre-compensated micro-arch sidewall 1, which would significantly increase the amount of tunneling work, the maximum outward convex arch height 'a' should also be checked for economic efficiency.

[0082] Preferably, the ratio of the maximum outward arch height 'a' to the effective net width 'B' of the tunnel design is controlled within 5% to 15%. In this embodiment, when B is 5500 mm and a is 339 mm, a / B is approximately 6.16%, which is within the preferred range of 5% to 15%, and can meet the pre-compensation requirements for deformation of both sides without significantly increasing the amount of tunneling work.

[0083] Furthermore, when the pre-compensated micro-arched sidewall 1 adopts a circular arc micro-arch, such as Figure 3 As shown, the formula for calculating the radius R of the arc is:

[0084] ;

[0085] In this embodiment, the pre-compensated micro-arched sidewall 1 adopts a circular arc micro-arch structure, effectively increasing the sidewall height H. b Taking 4000mm as the maximum outer arch height a as 339mm, the radius of the arc can be calculated as R = 6069.2mm according to the formula.

[0086] Therefore, in this embodiment, the radius R of the pre-compensated micro-arched sidewall 1 is approximately 6069mm. During construction layout, the preset clearance control line 2 is used as a reference, and the outermost point with the maximum outward arch height a of 339mm is determined on its outer side. The arc contours of the two sides are then laid out according to the radius R = 6069mm.

[0087] For roadways where the forming conditions of a roadway are limited, a multi-segment broken line can be used to approximate the micro-arch curve, and the outer envelope of the broken line should not be smaller than the designed micro-arch profile.

[0088] S4. Tunneling is carried out according to the design outline of the pre-compensated micro-arched sidewall 1, so that the roadway is formed by the roof 3, the bottom 4 and the pre-compensated micro-arched sidewall 1 protruding outward on both sides to form a pre-compensated micro-arched sidewall cross-section structure.

[0089] Specifically, during the tunneling process, the effective cross-section 7 of the tunnel design is first determined by the preset clearance control line 2, and then the design outline of the pre-compensated micro-arch sidewall 1 is laid out outside the preset clearance control line 2.

[0090] In this embodiment, two preset clearance control lines 2 are first marked on site, and then 339mm is used as the maximum outward arch height of the two sides. The design outline of the pre-compensated micro-arched side wall 1 is laid out outside the preset clearance control lines 2.

[0091] During the tunneling process, the cross-section can be controlled by a laser pointer, total station, cross-section forming instrument or tunneling machine cutting trajectory control system; the tunneling equipment can be formed along the design contour by a roadheader, roadheader or blasting method; the pre-compensated micro-arch sidewall 1 after forming is connected to the top plate 3 and bottom plate 4 by rounded corner transition or short straight section transition to reduce local stress concentration at the shoulder angle and bottom angle.

[0092] Through the above forming method, the deformation compensation space of the two sides of the tunnel is pre-arranged outside the effective cross section 7 of the tunnel design, providing geometric space for the controlled convergence of the two sides in the later stage.

[0093] S5. Install anchor bolts, anchor cables or steel strand support components on the top plate 3 and the two pre-compensated micro-arched side walls 1 to constrain the inward convergence process of the pre-compensated micro-arched side walls 1.

[0094] Specifically, the top plate 3 is supported by a combination of anchor bolts and anchor cables, and the two pre-compensated micro-arched side walls 1 are supported by a combination of side anchor cables, metal mesh, and steel reinforcement beams.

[0095] In this embodiment, the anchor bolt length is 2400mm, the top plate anchor cable length is 6300mm, and the side anchor cables length is 3300mm. The side anchor cables are preferably arranged along the normal direction of the curved surface of the pre-compensated micro-arched sidewall 1 so that the support force matches the sidewall convergence direction.

[0096] Through the above support method, the pre-compensated micro-arch sidewall 1 can generate controlled inward convergence under the action of surrounding rock pressure, instead of disordered spalling or local sudden failure. The role of the support components is not to completely prevent the sidewall deformation, but to constrain the sidewall convergence process, so that the pre-compensated micro-arch sidewall 1 gradually approaches the preset clearance control line 2, thereby achieving the coordination of deformation release and section maintenance.

[0097] S6. During the service of the roadway, the pre-compensated micro-arch sidewall 1 converges in a controlled manner towards the inside of the roadway under the action of the surrounding rock pressure, and approaches the preset clearance control line 2, so as to keep the effective cross-section of the roadway from being reduced due to the deformation of the two sides.

[0098] Specifically, such as Figure 2 As shown, in the early stage of tunnel excavation, the two sides are pre-compensated micro-arched sidewalls 1 protruding outward from the tunnel. As the stress of the surrounding rock is released, the soft rock rheology and mining disturbance are affected, the two sides converge towards the inside of the tunnel. When the convergence process is controlled, the deformed sidewall outline 8 of the pre-compensated micro-arched sidewall 1 approaches the preset clearance control line 2, or is still located outside the preset clearance control line 2.

[0099] At this point, the actual net width and actual net area of ​​the tunnel shall not be less than the effective net width and effective cross-sectional area of ​​the tunnel, and the effective cross-sectional area of ​​the tunnel shall be kept within the design range.

[0100] To facilitate the assessment of the convergence status of the pre-compensated micro-arched sidewall 1, real-time convergence measurements can be obtained using methods such as roadway surface convergence monitoring stations, cross-section instruments, 3D laser scanning, flexible survey lines, or digital image monitoring. When the real-time convergence measurement is less than the design convergence measurement, the original support parameters are maintained. When the real-time convergence measurement approaches or exceeds the design convergence measurement, reinforcement control is implemented through additional anchor bolts, additional anchor cables, secondary shotcreting, grouting reinforcement, or the addition of pressure-relief components. Simultaneously, the monitoring results can be fed back into the subsequent roadway excavation section design to correct the maximum outward arch height 'a' of subsequent sections.

[0101] In this embodiment, after the roadway is put into service, the two sides converge inward in a controlled manner under the action of the surrounding rock pressure. After deformation, the side profile 8 gradually approaches the preset clearance control line 2. The actual net width of the roadway still meets the design effective net width requirement of 5500mm, thereby achieving effective cross-section maintenance.

[0102] The above description of the disclosed embodiments enables those skilled in the art to make and use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pre-compensated micro-arch sidewall roadway structure, characterized in that, The structure includes a top plate (3), a bottom plate (4), and two symmetrically arranged pre-compensated micro-arched sidewalls (1); the top plate (3), bottom plate (4), and the two pre-compensated micro-arched sidewalls (1) together form a closed roadway cross-section; the roadway is equipped with a roadway design effective cross-section (7) to define the service limit boundary of the roadway, and vertical preset clearance control lines (2) are set on the left and right sides of the roadway design effective cross-section (7); the initial excavation outline of the two pre-compensated micro-arched sidewalls (1) protrudes outward and is arranged on the opposite side. The pre-compensated micro-arched sidewall (1) is located outside the pre-set clearance control line (2) and is used to pre-compensate the internal squeezing deformation of the two sides during the service life of the surrounding rock of the roadway. The top plate (3) and the surface of the pre-compensated micro-arched sidewall (1) are uniformly provided with support components, which are any one or more of anchor bolts (5), anchor cables (6), and steel strands. The pre-compensated micro-arched sidewall (1) can converge inward in a controlled manner under the action of surrounding rock pressure and mining disturbance, and the final convergence profile does not invade the inside of the pre-set clearance control line (2), keeping the effective cross-section (7) of the roadway unchanged.

2. A method for maintaining the effective cross-section of a pre-compensated micro-arch roadway, characterized in that, The method applied to the pre-compensated micro-arched roadway structure of claim 1 includes the following steps: S1. Collect the engineering foundation parameters of the roadway to be excavated (10) and the adjacent roadway that has been excavated, and obtain the side convergence monitoring data of the adjacent roadway or the test section roadway. S2. Based on the needs of ventilation, transportation, equipment access and personnel operation in the roadway, determine the effective cross section (7) of the roadway design, and lay out two parallel pre-set clearance control lines (2) on the left and right sides of the effective cross section (7) of the roadway design. S3. Based on the engineering basic parameters and the side convergence monitoring data, predict the maximum inward convergence of the two sides of the roadway (10) during the entire service cycle, calculate the corresponding outward convexity compensation amount, and complete the contour parameter design of the pre-compensated micro-arch sidewall (1) based on the outward convexity compensation amount. S4. Cut and excavate the tunnel (10) to be excavated according to the design outline to form a closed tunnel section consisting of the roof plate (3), the bottom plate (4) and the double-sided pre-compensated micro-arched sidewalls (1); S5. Support components are installed on the roof (3) and the double-sided pre-compensated micro-arched sidewalls (1) of the roadway. The support components are anchor bolts (5), anchor cables (6) or steel strands to constrain the disorderly abrupt deformation of the pre-compensated micro-arched sidewalls (1) and realize the controllable sidewall convergence process. S6. During the service phase of the roadway, real-time monitoring of the convergence deformation data of the pre-compensated micro-arched sidewall (1) is carried out to control the inward deformation of the pre-compensated micro-arched sidewall (1). After deformation, the sidewall outline (8) gradually approaches the preset clearance control line (2) to keep the effective cross-section (7) of the roadway design unchanged.

3. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 2, characterized in that, In step S1, the basic engineering parameters include the effective cross-section of the tunnel design (7), the effective net width of the tunnel design, the effective net height of the tunnel design, the physical and mechanical parameters of the surrounding rock, and the original rock stress and mining stress parameters. The surrounding rock physical and mechanical parameters include the uniaxial compressive strength, tensile strength, cohesion, internal friction angle, elastic modulus, Poisson's ratio, softening coefficient, and joint and fracture development characteristics of the coal and rock mass. The original rock stress and mining stress parameters include vertical ground stress, maximum horizontal principal stress, minimum horizontal principal stress, mining influence coefficient, and roadway depth. The sidewall convergence monitoring data is a dataset of the displacement of the left and right sides of the roadway over time.

4. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 2, characterized in that, In step S2, both of the preset clearance control lines (2) are vertical straight lines, and the distance between the two preset clearance control lines (2) is equal to the effective net width of the roadway design corresponding to the effective cross section (7) of the roadway design. The initial excavation profile of the pre-compensated micro-arched sidewall (1) is located outside the preset clearance control line (2). The final profile of the pre-compensated micro-arched sidewall (1) after controlled convergence fits the preset clearance control line (2) or maintains a safe distance from the preset clearance control line (2).

5. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 2, characterized in that, In step S3, the formula for calculating the maximum outward arch height a of the pre-compensated micro-arched sidewall (1) is as follows: ; Among them, a σ The arch height is controlled by theoretical stress; a u To compensate for the arch height due to deformation, a u Used to compensate for the inward convergence deformation of the pre-compensated micro-arch sidewall (1) caused by the rheology of the surrounding rock and mining disturbance in the later stage.

6. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 5, characterized in that, The theoretical stress controls the arch height a σ The calculation method is as follows: ; Where, η σ The theoretical arch height ratio is calculated using the following formula: B represents the effective net width of the tunnel design; σ n For the normal stress concentration on the sidewall of the roadway, σ c It represents the shear strength of the coal and rock mass.

7. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 5, characterized in that, The deformation compensation arch height a u The calculation formula is: ; In the formula, u is the corrected maximum inward convergence of a single rock face, λ is the surrounding rock deformation correction coefficient, and Δ is the safety compensation amount. The formula for calculating u is: ; In the formula, u0 is the basic value of maximum inward convergence of a single side, and k m k is the correction factor for on-site monitoring. s The support constraint correction coefficient; the on-site monitoring correction coefficient k m Used to correct the differences in parameters such as burial depth, original rock stress, mining intensity, coal and rock mechanical properties, and fracture development between the roadway to be excavated (10) and adjacent roadways; the support constraint correction coefficient k s Used to characterize the support components composed of anchor bolts (5), anchor cables (6) and steel strands, and their ability to suppress the inward convergence deformation of the pre-compensated micro-arched sidewall (1); When the geological conditions, stress conditions, and support parameters of the tunnel to be excavated (10) are consistent with those of the adjacent tunnels, k m k s The value approaches 1; When the disturbance of the roadway to be excavated (10) is stronger than that of the adjacent roadway and the surrounding rock is weaker than that of the adjacent roadway, k m The value is greater than 1; When the support strength of the roadway to be excavated (10) is higher than that of the adjacent roadway, k s The value is less than 1.

8. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 5, characterized in that, The engineering economics of the maximum outward arch height 'a' are checked, and the ratio of the maximum outward arch height 'a' to the effective net width B of the roadway is controlled to be within the range of 5% to 15%. If the calculated maximum outward arch height a exceeds the preset range, it can be jointly controlled by enhancing the support strength of anchor rods (5) and anchor cables (6), adding side support components, grouting the surrounding rock, assembling pressure relief components, and adjusting the outward arch height of the double-sided pre-compensated micro-arch sidewalls (1) in any one or more ways.

9. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 2, characterized in that, In step S3, the pre-compensated micro-arched sidewall (1) adopts a circular arc structure, and the formula for calculating the radius R of the circular arc is: ; In the formula, H b To pre-compensate the effective vertical support height between the top plate (3) and the bottom plate (4) corresponding to the micro-arched sidewall (1), a is the maximum outward arch height of the pre-compensated micro-arched sidewall (1).

10. The method for maintaining the effective cross-section of a pre-compensated micro-arch roadway according to claim 2, characterized in that, In step S4, the connection between the pre-compensated micro-arched sidewall (1) and the top plate (3) and bottom plate (4) adopts a rounded transition or a short straight section transition structure to weaken the stress concentration effect at the corner of the roadway; for tunneling equipment that does not have the conditions for direct arc cutting, the roadway cross-section forming operation is completed by using a multi-segment broken line fitting arc contour. And / or, in step S6, the criteria for determining the effective cross-section of the roadway are: during the service period, the deformed sidewall profile (8) corresponding to the pre-compensated micro-arched sidewall (1) is located outside the preset clearance control line (2) or coincides with the preset clearance control line (2), and the real-time net width and real-time cross-sectional area of ​​the roadway are not less than the designed effective net width and the designed effective cross-sectional area (7) of the roadway, respectively; the convergence deformation data of the pre-compensated micro-arched sidewall (1) are collected by the convergence station and the three-dimensional laser scanner. When the convergence deformation is close to the warning threshold, the roadway reinforcement and support are completed by adding anchor bolts (5), anchor cables (6), secondary grouting, and shotcreting reinforcement.

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