Comprehensive roadway surrounding rock control method

Abstract

The invention provides a comprehensive roadway surrounding rock control method. The method comprises the following steps: according to field geological conditions, roof and surrounding rock failure characteristics and small coal pillar size requirements, determining a working face periodic weighting step pitch, a roadway width and goaf distribution; establishing a mechanical model based on a basic top arc-shaped triangular block, deducing primary support design parameters, and cutting a roadway by using a heading machine to implement primary support; a pre-delay stage is set after primary supporting is completed, and after it is confirmed that a supporting system meets the design requirement by monitoring surrounding rock deformation and roof settlement in real time, layered roof cutting and pressure relief are conducted on a roof on the outer side of a small coal pillar through a directional pre-joint-cutting technology; and after top cutting, secondary support reinforcement is rapidly carried out according to feedback data. According to the method, accurate separation of supporting and roof cutting procedures in time is achieved, the roof pressure relief effect is optimized, the risks of local surrounding rock instability and large deformation of small coal pillars are reduced, and meanwhile engineering construction safety and economic benefits are improved.

Description

Technical Field

[0001] The present invention relates to a comprehensive roadway surrounding rock control method, belonging to the field of roadway surrounding rock control methods. Background Art

[0002] In the past roadway mining process, in order to reduce the risk of excessive settlement or local instability caused by the direct action of the roof load on the small coal pillar, the directional pre-splitting technology is usually used for layered roof cutting and pressure relief. However, due to improper timing of roof cutting construction, there are the following two contradictions:

[0003] Premature roof cutting: Starting roof cutting before the support system fully exerts its bearing capacity may cause local surrounding rock instability and a sharp increase in settlement, thereby affecting the stability of the small coal pillar;

[0004] Delayed roof cutting: Delaying the roof cutting operation will make the roof pressure relief effect not obvious, and the direct roof load continuously acts on the small coal pillar, resulting in excessive support load and the risk of large deformation.

[0005] Therefore, how to accurately control the roof cutting timing and achieve the "time sequence separation" of support and pressure relief on the premise of meeting the support requirements has become an urgent technical problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to design a comprehensive roadway surrounding rock control method to overcome the deficiencies of the prior art.

[0007] The technical solution of the present invention is: to provide a comprehensive roadway surrounding rock control method, including the following steps:

[0008] S1. Determine the periodic weighting interval of the working face, the roadway width, and the goaf distribution according to the specific geological conditions of the mining area, the failure characteristics of the roof and surrounding rocks, and the size requirements of the small coal pillar;

[0009] S2. Establish a mechanical analysis model based on the arc triangular block of the main roof, and deduce the design parameters required for the primary support;

[0010] S3. Use a roadheader to cut the roadway, and first carry out the primary support construction of the roadway, and complete the preliminary support with bolts, cables, and mesh members;

[0011] S4. After the initial support is completed, set a pre-delay stage, and continuously monitor the surrounding rock deformation and roof settlement during this period;

[0012] S5. When the monitoring data shows that the initial support system has reached the design requirements and it is confirmed that the local surrounding rock has reached a stable state, enter the next stage of construction;

[0013] S6. After the pre-delay stage ends, use the directional pre-splitting technology to carry out layered roof cutting on the roof outside the small coal pillar;

[0014] After the roof cutting operation is completed, according to the monitoring feedback and the results of mechanical calculations, the roadway is immediately reinforced by secondary support.

[0015] Specifically, the calculation method of the weighting interval is as follows:

[0016]

[0017] Wherein, L is the weighting interval, H 1 is the thickness of the main roof, σ ′ is the tensile strength of the main roof, and P is the load per unit area of the overlying strata on the main roof.

[0018] Specifically, the establishment of the mechanical analysis model based on the arc triangular block of the main roof in step S2 specifically includes:

[0019] The arc triangular block of the main roof is simplified into a cantilever beam model with one end hinged and one end free, and assuming that the action of the overlying strata is a uniformly distributed load, a vertical force balance equation is established. Considering that the support force provided by the coal pillar also acts as a uniformly distributed load, the design strength parameters required for the primary support are derived.

[0020] Specifically, the design strength parameters required for the primary support include: the strength of the support member, the parameters of bolts and cables.

[0021] Furthermore, the pre-delay stage is the support stability period.

[0022] Furthermore, in step S5, when the monitoring data shows that the initial support system has reached the design requirements, it specifically includes: the deformation rate tends to be stable and the stress of the bolts is stable.

[0023] Furthermore, in step S6, the roof cutting operation is carried out strictly according to the pre-set time sequence: first, partial cutting is performed on part of the roof, so that the direct top outside the small coal pillar is locally cut along the edge of the coal pillar, and local pressure relief is immediately achieved. During the roof cutting construction process, combined with the real-time monitoring data, the cutting depth and cutting sequence are controlled to ensure that the pressure relief effect is coordinated and matched with the local support bearing capacity.

[0024] Furthermore, the secondary support measures in step S7 include reinforcement with high-strength bolts or cables and necessary concrete spraying or grouting reinforcement.

[0025] The beneficial effects of the present invention are: compared with the prior art,

[0026] 1) After the initial support is completed, by setting the pre-delay stage and carrying out real-time monitoring, the present invention ensures that the support system fully plays its role, reduces the risk of local instability caused by incomplete support or uneven stress distribution. This stable support state provides safety guarantee for the subsequent roof cutting operation;

[0027] 2) By adopting the directional pre - cutting seam technology, the invention stratifies the roof cutting outside the small coal pillar and strictly constructs according to the predetermined sequence, avoiding the contradiction of premature roof cutting (resulting in local instability) or delayed roof cutting (insufficient pressure relief and the direct roof load continuously acting on the small coal pillar), making the roof pressure relief more balanced, effectively reducing the stress concentration and large deformation risk of the small coal pillar;

[0028] 3) By starting the roof cutting operation after the support is stable, this method not only reduces the safety hazards brought by sudden surrounding rock instability during the construction process, but also avoids over - support and unnecessary reinforcement, thus reducing the waste of construction materials and cost expenditure, and improving the overall engineering economic benefits;

[0029] 4) The support design parameters derived from the mechanical analysis model of the basic roof arc - shaped triangular block of the invention provide an accurate basis for the selection and layout of bolt, cable and grid members. At the same time, the real - time monitoring data feedback enables the construction process to be dynamically adjusted according to the on - site changes;

[0030] 5) By organically integrating steps such as on - site parameter measurement, mechanical model establishment, initial support, support stability confirmation, stratified roof cutting and secondary support reinforcement, a closed - loop control system is formed, which not only improves the construction efficiency, but also enhances the control ability of the overall stability state of the surrounding rock, extends the service life of the mine, and ensures the safety and efficiency of mining operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the flow chart of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] To make the objectives, technical solutions and advantages of the invention more clear, the invention will be further described in detail below with reference to the drawings of this specification.

[0033] Refer to Figure 1 , a comprehensive roadway surrounding rock control method, including the following steps:

[0034] Step S1 - On - site parameter measurement and design parameter determination

[0035] 1.1 Conduct a detailed geological survey of the construction area on - site, collect the geological and physical - mechanical parameters of the roof, basic roof and surrounding rock by means of drilling, ground penetrating radar, etc., and determine the goaf distribution, the periodic weighting interval of the working face and the roadway section size.

[0036] 1.2 According to the laboratory test data and on - site stress test data, calculate the optimal weighting interval using formula (1), and determine the roadway width and small coal pillar size in combination with the actual goaf situation:

[0037]

[0038] Among them, L is the weighting interval, H 1 is the thickness of the main roof, σ ′ is the tensile strength of the main roof, and P is the load per unit area of the overlying strata of the main roof.

[0039] Step S2 - Establishing a mechanical analysis model and deriving design parameters

[0040] 2.1 Simplify the arc triangular block of the main roof into a cantilever beam model with one end hinged and one end free. Assume that a uniform load is applied by the overlying strata, and establish a vertical force balance equation;

[0041] 2.2 Considering the supporting effect of the coal pillar, obtain the design strength parameters required for the primary support through theoretical derivation and numerical simulation, including the selection basis and layout parameters of bolts, cable bolts and grid members.

[0042] Step S3 - Initial support construction

[0043] 3.1 Use a roadheader to cut the roadway and complete the roadway excavation according to the design requirements;

[0044] 3.2 According to the design parameters determined in step S2, first carry out the primary support construction, lay out bolts, cable bolts and steel bar grids, and spray concrete to form an initial support system;

[0045] 3.3 At the same time, install a mine pressure monitor, a displacement sensor and a bolt non-destructive detector in the roadway to record the deformation and stress conditions of the surrounding rock and the support members in real time.

[0046] Step S4 - Pre-delay stage and monitoring

[0047] 4.1 After the initial support construction is completed, set a pre-delay stage (usually 3 to 7 days), during which continuously monitor the deformation of the surrounding rock, roof settlement and bolt stress;

[0048] 4.2 Through data acquisition, judge whether the support system has fully exerted its bearing capacity and ensure that the local stability of the surrounding rock meets the design requirements.

[0049] Step S5 - Confirming the support stability

[0050] 5.1 When the monitoring data shows that the deformation rate of the surrounding rock tends to be stable and the stress state of the bolts is stable, confirm that the local surrounding rock has reached a stable state and meets the subsequent construction conditions;

[0051] 5.2 Record and file the monitoring data to provide a technical basis for the next roof cutting operation.

[0052] Step S6 - Directional pre-slotting and layered roof cutting for pressure relief

[0053] 6.1 After the end of the pre-delay stage, the directional pre-splitting technology is adopted to perform layered roof cutting on the outer roof of the small coal pillar:

[0054] - First, perform local cutting on the local roof to cause the direct top outside the small coal pillar to locally fall along the edge of the coal pillar, quickly achieving local pressure relief;

[0055] - During the roof cutting process, combine the real-time monitoring data to control the cutting depth and cutting sequence to ensure that the roof pressure relief effect after cutting matches the local support bearing capacity.

[0056] 6.2 After the roof cutting operation is completed, detect the settlement amount and deformation state of the roof after pressure relief, and confirm that the pressure relief effect meets the design expectations.

[0057] Step S7 - Secondary support reinforcement

[0058] 7.1 According to the monitoring feedback after roof cutting and the results of mechanical calculations, immediately perform secondary support reinforcement on the roadway:

[0059] - Use high-strength bolts or cables for reinforcement, and cooperate with concrete spraying or grouting reinforcement if necessary;

[0060] - After the secondary support construction is completed, continue to dynamically monitor the stability of the surrounding rock to ensure that the entire support system is in a safe state for a long time.

[0061] The parts not detailed in the present invention are all well-known technologies to those skilled in the art. 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 them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A comprehensive tunnel surrounding rock control method, characterized in that: The following steps are involved: S1. According to the specific geological conditions of the mining area, the characteristics of roof and surrounding rock damage, and the requirements for the size of small coal pillars, determine the periodic pressure step distance of the working face, the width of the roadway, and the distribution of the goaf; S2. Establish a mechanical analysis model based on the basic top arc triangle block and derive the design parameters required for primary support; S3, using a tunnel boring machine to cut the tunnel, first carry out a support construction on the tunnel, and use anchor rods, anchor cables and grid components to complete the initial support; S4. After the initial support is completed, a pre-delay stage is set, during which the surrounding rock deformation and roof settlement are continuously monitored; S5. When the monitoring data shows that the initial support system has met the design requirements and the local surrounding rock has reached a stable state, the next stage of construction will begin; S6. After the pre-delay stage is over, the directional pre-cutting technology is used to cut the roof of the outer side of the small coal pillar in layers; S7. After the top cutting operation is completed, the tunnel shall be immediately reinforced with secondary support according to the monitoring feedback and mechanical calculation results.

2. The comprehensive tunnel surrounding rock control method according to claim 1 is characterized in that: The calculation method of the pressure step distance is: Among them, L is the pressure step distance, H1 is the basic top thickness, σ ′ is the tensile strength of the basic top, and P is the load per unit area of ​​the overlying strata above the basic top.

3. The comprehensive tunnel surrounding rock control method according to claim 1, characterized in that: The step S2 of establishing a mechanical analysis model based on the basic top arc triangle block specifically includes: The basic top arc-shaped triangular block is simplified into a cantilever beam model with one end hinged and the other end free. It is assumed that the overlying rock stratum acts as a uniformly distributed load, and the vertical force balance equation is established. Considering that the support force provided by the coal pillar also acts as a uniformly distributed load, the design strength parameters required for primary support are derived.

4. The comprehensive tunnel surrounding rock control method according to claim 3, characterized in that: The design strength parameters required for the primary support include: the strength of the support components, anchor rods and anchor cable parameters.

5. The comprehensive tunnel surrounding rock control method according to claim 1, characterized in that: The pre-delay stage is the support stabilization period.

6. The comprehensive tunnel surrounding rock control method according to claim 1, characterized in that: In step S5, when the monitoring data indicates that the initial support system has met the design requirements, specifically including: the deformation rate tends to be stable and the anchor force is stable.

7. The comprehensive tunnel surrounding rock control method according to claim 1, characterized in that: The top cutting operation in step S6 is strictly carried out according to the preset timing: first, local cutting is carried out on part of the roof, so that the top of the outer side of the small coal pillar is locally cut off along the edge of the coal pillar, and local pressure relief is immediately achieved. During the top cutting construction process, the cutting depth and cutting sequence are controlled in combination with real-time monitoring data to ensure that the pressure relief effect is coordinated with the local support bearing capacity.

8. The comprehensive tunnel surrounding rock control method according to claim 1, characterized in that: The secondary support measures in step S7 include high-strength anchor rod or anchor cable reinforcement and necessary concrete spraying or grouting reinforcement.

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