Design method of impact environment flexible mode pumping prop support system

Abstract

The application discloses a kind of impact environment soft mode pumping prop support system design methods, comprising the following steps: static load environment prop design parameter: obtaining the size information of mining roadway in mining range, mining roadway surrounding rock information, mining roadway anchoring design information, complete the design of prop under the action of roadway roof load, result includes prop height, prop diameter, prop design quantity, single prop support area to roadway roof;Obtain prop dynamic load support strength: make impact test block to carry out impact test, obtain the dynamic load strength of prop, the dynamic load support strength of roadway roof;Prop design parameter correction under impact environment: obtain the support strength of hydraulic support on working face and compare with dynamic load support strength, the application can accurately determine the optimal setting size and quantity of soft mode pumping prop, both ensure the support effect of soft mode pumping prop, avoid excessive design, save mining roadway support cost, realize the balance of safety and economy.

Description

Technical Field

[0001] This invention relates to the field of advanced support in fully mechanized mining operations. More specifically, this invention relates to a design method for a flexible mold pumped prop support system in impact environments. Background Technology

[0002] In current fully mechanized mining operations, the return roadway is a roadway excavated during coal mining for coal recovery. It is mainly used for coal transportation, ventilation, personnel access, and the placement of mining equipment. Depending on its location and function within the mining face, the return roadway can be classified as a transport roadway, return airway, etc. As the mining face advances, the roof of the return roadway is affected by mining activity, causing deformation and damage. Installing advance support within the return roadway can effectively support the roof before significant deformation occurs, preventing sudden roof collapse, avoiding roof fall accidents, and eliminating safety hazards.

[0003] Advance support for longwall mining roadways is crucial. In current longwall roadway support technologies, flexible molded pump props, as a novel type of support component, offer advantages such as low cost, easy construction, and good mechanical properties. They are gradually being applied in related projects with good results. Currently, there is considerable research on the design methods of flexible molded pump props under static roof loads. Specifically, Chinese authorized patent CN110397448B and the literature "Research and Application of Parameter Optimization for Coal Pillar Recovery Pump Props in Fully Mechanized Mining Faces" propose a design optimization method for flexible molded pump props. This method scientifically and effectively completes the design of pump prop dimensions and row spacing while ensuring effective roadway support, achieving good support effects and cost savings. However, this parameter optimization method is applicable to the design of flexible molded pump props under static load conditions and lacks consideration of the bearing capacity of flexible molded pump props under ground pressure impact.

[0004] In working environments where rock bursts are possible, and in mining methods using the direct caving method, the pre-support of the mining roadway will be subjected to the impact load when the roof collapses. If no targeted design is carried out, the flexible mold pumped props that only meet the static load are prone to crushing under sudden pressure, posing a significant safety hazard to the mining roadway. Currently, there is an urgent need for a parameter optimization method that can effectively guide the design of the size and layout of flexible mold pumped props in impact environments. Summary of the Invention

[0005] One objective of this invention is to provide a design method for a flexible mold pumping support system in an impact environment. This method, based on the stress characteristics of the flexible mold pumping support, can calculate the optimal size and quantity of the flexible mold pumping support in an impact environment, thereby avoiding safety risks and saving costs.

[0006] To achieve these objectives and other advantages according to the present invention, the present invention provides a design method for a flexible molded pumped prop support system for impact environments, comprising the following steps: S1. Obtain the support design parameters under static load: Obtain the size information of the mining roadway, the surrounding rock information of the mining roadway, and the anchoring design information of the mining roadway within the mining area of ​​the working face, and complete the support design under the load of the roadway roof. The design results include the support height h, the support diameter w, the number of supports N, and the support area S of a single support on the roadway roof. S2. Obtain the dynamic load support strength of the support column: Impact test blocks are fabricated using the same material as the support column, and impact tests are conducted on the impact test blocks to obtain the dynamic load strength σ of the support column. t And the dynamic load support strength q of the support column on the roadway roof. a The formula for calculating the dynamic load support strength is as follows: ; S3. Correct the support column design parameters under impact conditions: Obtain the hydraulic support strength q on the working surface. t If q a >q t The design results meet the dynamic load support requirements of the longwall mining roadway, if q a ≤q t If so, the number of support pillars in the design should be increased.

[0007] Preferably, the support includes a filling bag and a plurality of circumferential ribs spaced apart on the inner surface of the filling bag, wherein the support filling material fills and solidifies inside the filling bag to form a support.

[0008] Preferably, the surrounding rock information of the mining roadway includes the rock mass unit weight γ, the roadway caving width B, and the roadway caving height H; the anchoring design information of the mining roadway includes the anchor cable spacing a, the anchor cable anchoring force p', the number of anchor cables per row n, and the roadway support length L; and the support design under the roof load includes the following steps: A1. Determine the support diameter w based on the dimensions of the mining roadway and the working space requirements; A2. Calculate the design value P of the bearing capacity of a single support column. a The calculation formula is: Where r is the radius of the support column, σ is the axial compression test strength of the support column filling material specimen, and f s The structural strength coefficient is the Goohl coefficient. A3. Calculate the design number N of supports under the most unfavorable top slab load condition. The calculation formula is as follows: , where f is the anchoring force weakening coefficient; A4. Calculate the support area S of a single support pillar on the tunnel roof.

[0009] Preferably, step S2 includes the following steps: S21. Using the same material as the support column, make multiple cylindrical impact-resistant test blocks with dimensions of Ф50mm×50mm; S22. Using the Hopkinson bar test system, impact the impact test blocks one by one at different impact velocities and record the data, including the transmitted wave intensity σ corresponding to each test. ’ t ; S23. Observe the damage of the impact-resistant test blocks under different impact velocities, and use the transmitted wave intensity σ corresponding to the impact-resistant test block when a through crack is about to appear. ’ t As the dynamic strength of the test block; S24. Based on the height-to-diameter ratio of a single support column in the support column design results, the dynamic strength of the test block is corrected to obtain the dynamic load strength σ. t And obtain the dynamic load support strength q a .

[0010] Preferably, A1 includes the following steps: A11. Using the same material as the support column, multiple sets of height-to-diameter ratio specimens with varying height-to-diameter ratios from low to high were produced. A12. Apply axial compression to the high-to-diameter ratio specimens sequentially from high to low and record the compressive strength and the relative increase in the bearing capacity of the specimens with the previous high-to-diameter ratio specimens. Obtain the high-to-diameter ratio specimen with the maximum relative increase in bearing capacity. A13. The height-to-diameter ratio of the test block with the largest relative increase in bearing capacity is taken as the design height-to-diameter ratio of the support. The height of the support is h, and the diameter w of the support is calculated.

[0011] Preferably, the calculation formula for correcting the dynamic strength of the test block is as follows: .

[0012] Preferably, the formula for calculating the design value of the bearing capacity of a single support column is as follows: , where σ c To correct for axial compressive strength, σ c The calculation formula is: ; ; ; Where d is the diameter of the circumferential reinforcement, s' is the spacing of the circumferential reinforcement, σ1 is the radial restraint stress of the circular section, and k e For effective constraint coefficients, P sv For the volumetric stirrup ratio of the circumferential reinforcement, σ yh For the yield strength of the circumferential reinforcement, d s The diameter of the column section surrounded by circumferential reinforcement.

[0013] Preferably, S3 includes: S4. Based on the calculation results obtained in S3, the props are arranged in the mining roadway where the first mining is carried out, and monitoring points are set up to monitor the prop pressure in real time. S5. Based on the column pressure variation pattern obtained in S4, recalculate the column construction parameters; S6. Arrange supports in the subsequent mining roadway based on the calculation results of S5.

[0014] Preferably, a hydraulic pillow is used to monitor the support pressure.

[0015] Preferably, the diameter of the hydraulic pillow is equal to the diameter of the support column.

[0016] The present invention has at least the following beneficial effects: First, this invention is based on the design of flexible mold pumped props under static load on the roof. It further refines the design based on the stress characteristics of flexible mold pumped props under impact load, fully considering the stress characteristics of advanced support in the presence of impact load. It solves the limitation of relying solely on static load conditions for the parameter design of flexible mold pumped props, effectively improving the applicability of the advanced support system using flexible mold pumped props in impact environments. The design results meet the safety requirements of the support system and ensure safe mining of the working face.

[0017] Secondly, through multi-step calculations and experiments, this invention can accurately determine the optimal size and quantity of flexible mold pumping props under impact loads, ensuring the support effect of the flexible mold pumping props while avoiding over-design, saving support costs in the roadway, and achieving a balance between safety and economy.

[0018] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0019] Figure 1 This is a flowchart of an optimized design method for a flexible mold pumping support column in one technical solution of the present invention; Figure 2 This is a structural diagram of the flexible mold pumping support column in one technical solution of the present invention; Figure 3 This is a schematic diagram of the working surface 13128 in an embodiment of the present invention; Figure 4 The figures shown are cross-sectional and unfolded views of the anchor cable support in the return airway 13128 in this embodiment of the invention. Figure 5 This is a curve showing the relative increase in bearing capacity of the height-to-diameter ratio specimen in an embodiment of the present invention; Figure 6The stress wave curve corresponding to the impact-resistant test block with an impact velocity of 10.16 m in this embodiment of the invention is shown. Figure 7 This is a design diagram of the arrangement position of the flexible mold pumping support column in an embodiment of the present invention; Figure 8 This is the relationship curve between the stress at the monitoring point and the distance from the working surface in an embodiment of the present invention.

[0020] Attached diagram descriptions: 1-support column, 2-filling bag, 3-circumferential reinforcement, 4-lifting lug, 5-wooden strip support, 6-expansion hook, 7-grouting port, 8-diagonal support. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description.

[0022] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0023] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials mentioned are commercially available. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] like Figure 1-6 As shown, the present invention provides a design method for a flexible mold pumped prop support system for impact environments, comprising the following steps: S1. Obtain the dimensions of the mining roadway, the surrounding rock information, and the anchoring design information within the mining area of ​​the working face. Complete the support design under the roof load. The design results include the support height h, the support diameter w, the number of supports N, and the support area S of a single support 1 on the roadway roof. Specifically, under the static load of the roof, the axial bearing capacity of support 1 is evaluated through mechanical calculations and static mechanical property tests of the materials used. The bearing capacity design value of support 1 under static load is estimated by multiplying the compressive strength obtained from the test by the cross-sectional area of ​​support 1. Support 1 is a flexible mold pumped support. In the design parameters of support 1, the support height h is equal to the height of the mining roadway. The support diameter can be determined according to the empirical formula of the optimal height-to-diameter ratio or through the test results of the optimal height-to-diameter ratio. The number of supports 1 is derived from the calculation results of the roadway roof load and the bearing capacity design value of a single support 1. The design parameters also include the support spacing and the support row spacing. The design parameters need to meet the space requirements for pedestrian and transportation equipment passage, as well as the installation of ventilation ducts, cables, and other facilities.

[0025] S2. Using the same material as the support column 1, an impact-resistant test block is made, and an impact test is conducted on the impact-resistant test block to obtain the dynamic load strength σ of the support column 1. t And the dynamic load support strength q of pillar 1 to the roadway roof. a The formula for calculating the dynamic load support strength is as follows: Specifically, in the mining process using the complete caving method and in working faces with rock bursts, support column 1 must effectively resist impacts without failure. In order to determine the dynamic load capacity of support column 1, impact tests such as the Hopkinson bar test system, drop hammer impact test, and pendulum impact test are used. In accordance with relevant test specifications and the principle of scaled specimen fabrication, impact-resistant test blocks are made, and impact tests are conducted on the impact-resistant test blocks to obtain dynamic strength. When judging the dynamic strength of impact-resistant test blocks, the criterion is that the test block does not produce a through crack under an impact of a certain intensity and still maintains good static load bearing capacity after the impact. It can be considered that the impact-resistant test block will crush when subjected to an impact higher than this intensity. Then, based on the support area S of the single support column 1 to the roadway roof obtained in step S1, the dynamic load support strength q of the support column 1 to the roof can be calculated. a .

[0026] S3. Obtain the hydraulic support strength q on the working surface. t If q a >q t If the design results meet the dynamic load support requirements of the longwall mining roadway, then q a ≤q t Then increase the number of support columns until q. a >q tSpecifically, during the mining process at the longwall face, stress redistribution occurs in the surrounding rock strata, and mining pressure is transmitted towards the longwall roadway. Therefore, the support strength of the longwall roadway cannot be lower than the support strength of the hydraulic props at the working face, and the dynamic load support strength q of the roof must be maintained. a With respect to the hydraulic support strength q on the working surface t Compare, if q a ≥q t This indicates that the support column 1, designed according to the static load bearing requirements of the roof slab, can meet the stress requirements for the dynamic load of the roof slab, and the design result of step S1 can be used. However, when q... a ≤q t If the current condition is met, it indicates that although the existing support 1 design can meet the static load requirements of the roof, it cannot withstand the impact load when the roof collapses. Support 1 will be crushed when under pressure, and the mining roadway will be damaged when under impact. Therefore, it is necessary to increase the number of support 1 in the calculation area of ​​the mining roadway.

[0027] In another technical solution, the support column 1 includes a filling bag 2 and several circumferential reinforcing bars 3 spaced apart on the inner surface of the filling bag 2. The support column filling material fills and solidifies inside the filling bag 2 to form a support body. The filling bag 2 is provided with a grouting port 7 at the top and an exhaust hole at the top. The support column 1 also includes lifting lugs 4 and wooden strip supports 5. Anchoring sections of expansion hooks 6 corresponding to the number of lifting lugs 4 are fixed to the roadway roof. The filling bag 2 is connected to the expansion hooks 6 through the lifting lugs 4. The wooden strip supports 5 are fixedly connected to the steel reinforcement rings provided on the outside of the filling bag 2. An inclined support 8 is provided at the bottom of the filling bag 2 to stabilize and reinforce the support column 1. When constructing the support column 1, the filling bag 2 is first hung up through the lifting lugs 4, and then the prepared support column filling material is injected. After the support column filling material is poured and solidified, it plays a supporting role. In this technical solution, although the filling bag 2 and the circumferential reinforcing bars 3 do not directly bear the load, they play a restraining role on the solidified support column filling material inside during the subsequent stress process of the support column 1, and improve the load-bearing capacity and energy dissipation capacity of the support column 1 to a certain extent.

[0028] In another technical solution, the surrounding rock information of the mining roadway includes the rock mass unit weight γ, the roadway caving width B, and the roadway caving height H. The anchoring design information of the mining roadway includes the anchor cable spacing a, the anchor cable anchoring force, the number of anchor cables per row n, and the roadway support length L. The support design under the roof load includes the following steps: A1. Determine the diameter of the support column based on the dimensions of the mining roadway and the working space requirements. Specifically, the diameter of the support column can be determined based on the empirical formula for the optimal height-to-diameter ratio or by conducting a height-to-diameter ratio test. Under the optimal height-to-diameter ratio, support column 1 can withstand relatively high axial pressure while ensuring stability. In addition to considering the optimal height-to-diameter ratio, it is also necessary to consider that support column 1 will not affect personnel passage and equipment transportation in the mining roadway under this diameter design.

[0029] A2. Calculate the design value p of the bearing capacity of a single support column 1. a The calculation formula is: Where σ is the axial compression test strength of the support filling material specimen, and f s The structural strength is represented by the Gouldian coefficient. Specifically, using the same column filling material and filling bag 2 as in actual engineering projects, several full-size columns are fabricated and axial compression tests are conducted. The compression test results are used to obtain the design value of the single column bearing capacity through regression analysis. Optionally, axial compression test blocks conforming to the axial compression test standards can be fabricated using the same column filling material as in actual engineering projects. Multiple sets of axial compression tests are conducted according to the test specifications to obtain the axial compression test strength σ, f. s The value ranges from 0.9 to 1.

[0030] A3. Calculate the design number N of supports under the most unfavorable top slab load condition. The calculation formula is as follows: Where f is the anchoring force weakening coefficient; specifically, for a mining roadway with anchor cable reinforcement support, the most unfavorable roof load condition is that all rock strata within the anchoring range of the anchor cable are delaminated and the anchor cable is completely ineffective. At this time, the support column 1 is in a given load working state, and the required support load of the support column 1 can be determined, and its specific parameters can be determined. The roadway collapse width can be taken as the mining roadway width, the roadway collapse height can be taken as the anchor cable length, and the rock mass unit weight γ can be obtained through field collection or through experience.

[0031] A4. Calculate the spacing between the support pillars 1 and obtain the support area S of a single support pillar 1 for the roadway roof. Specifically, the support pillars 1 can be arranged in parallel or staggered rows throughout the roadway.

[0032] In another technical solution, S2 includes the following steps: S21. Using the same material as support column 1, multiple cylindrical impact test blocks with dimensions of Ф50mm×50mm are made. Specifically, using the same material as support column 1, the impact test blocks are scaled down. Each impact test block is a cylindrical test block filled with support column filling material in the filling bag 2. The impact test block covered with the filling bag 2 material can fully simulate the damage of support column 1 when it is impacted.

[0033] S22. Using the Hopkinson bar test system, impact the impact test blocks one by one at different impact velocities and record the data, including the transmitted wave intensity σ' corresponding to each test. tSpecifically, under actual stress, support column 1 is subjected to a short-duration, large-impact dynamic load in the axial direction. Compared with other impact tests, the Hopkinson bar test can better simulate the actual stress condition of support column 1. The Hopkinson bar test system consists of an impact bar, an incident bar, a transmission bar, and an impact-resistant specimen. Based on the principle of stress wave propagation in an elastic bar, the dynamic strength corresponding to the failure of the impact-resistant specimen can be obtained relatively accurately. When the impact bar impacts the incident bar at a certain speed, a stress wave is generated in the incident bar. The stress wave propagates along the incident bar to the impact-resistant specimen, which deforms under the action of the stress wave. Part of the stress wave passes through the specimen and is transmitted to the transmission bar. By measuring the incident stress wave in the incident bar and the transmitted stress wave in the transmission bar, the stress-strain relationship of the impact-resistant specimen under high strain rate can be calculated according to the one-dimensional stress wave theory. In this technical solution, the impact bar strikes each group of impact-resistant specimens at different speeds, and the transmitted wave amplitude and intensity corresponding to each impact are recorded.

[0034] S23. Observe the damage of the impact-resistant test blocks under different impact velocities, and use the transmitted wave intensity σ' corresponding to the impact-resistant test block when a through crack is about to appear. t The dynamic strength of the impact test specimen is used as a criterion. Specifically, dynamic strength refers to the ability of a material or component to resist failure under dynamic loads, and is usually measured by the maximum stress at which the impact test specimen reaches failure or yield. In the Hopkinson bar test, as the incident wave intensity gradually increases, the stress inside the impact test specimen also increases. When the impact test specimen reaches its dynamic strength, that is, when the impact test specimen is about to yield, undergo plastic deformation, or fail, the stress reflected by the transmitted wave in this critical state is approximately the maximum stress that the specimen can withstand. The occurrence of a through-crack in the impact test specimen can be used as a criterion for judging whether the specimen has failed, and the transmitted wave intensity corresponding to the first set of through-cracks in the impact test specimen can be used as the dynamic strength of the specimen.

[0035] S24. Based on the height-to-diameter ratio of a single support column in the support column design results, the dynamic strength of the test block is corrected to obtain the dynamic load strength σ. t And obtain the dynamic load support strength q a Specifically, since the impact test specimens in the Hopkinson bar test are standard cylindrical specimens with a height-to-diameter ratio of 1:1, while the actual support column 1 has a different height-to-diameter ratio, it is necessary to select an appropriate dynamic strength-height-to-diameter ratio calculation curve to correct the dynamic strength of the specimen obtained in step S23, and obtain the dynamic load strength σ of support column 1 under the corresponding height-to-diameter ratio. t .

[0036] In another technical solution, A1 includes the following steps: A11. Using the same material as the support column, multiple sets of height-to-diameter ratio specimens with varying height-to-diameter ratios from low to high were produced. A12. Apply axial compression to the high-to-diameter ratio specimens sequentially from high to low and record the compressive strength and the relative increase in the bearing capacity of the specimens with the previous high-to-diameter ratio specimens. Obtain the high-to-diameter ratio specimen with the maximum relative increase in bearing capacity. A13. The height-to-diameter ratio of the test block with the largest relative increase in bearing capacity is taken as the design height-to-diameter ratio of support 1. The diameter of the support is calculated by taking the roadway height as the support height h.

[0037] Specifically, a series of height-to-diameter ratio (HMR) specimens of equal height were prepared. The internal support filling material and filling bags 2 were identical to those used in the actual project. HMRs of 3, 3.5, 4, 4.5, and 5 were selected. Axial loading tests were conducted on the HMR specimens using an axial compression testing machine. During loading, uniform loading speed and other relevant test standards were ensured to obtain the maximum bearing capacity of the HMR specimens with different HMRs. The relative increase in bearing capacity was calculated, and the trend of this relative increase was observed. When the relative bearing capacity gradually increased as the HMR decreased, it indicated that reducing the HMR had a positive effect on improving the support's bearing capacity. When the HMR reached a certain value, the relative increase in bearing capacity began to decrease, indicating that further reducing the HMR had a weakening effect on improving the support's bearing capacity. At this point, the HMR corresponding to the inflection point and the maximum relative increase in bearing capacity can be considered the optimal HMR. The diameter of the support 1 was then designed based on this HMR.

[0038] In another technical solution, the calculation formula for correcting the dynamic strength of the test block is: Among them, the column diameter and column height are both optimal values, and the obtained σ t This is the dynamic load strength of support column 1 under the optimal dimensions.

[0039] In another technical solution, the formula for calculating the design value of the bearing capacity of a single support column 1 is: , where σ c To correct for axial compressive strength, σ c The calculation formula is: ; ; ; Where d is the diameter of the circumferential reinforcement, s' is the spacing of the circumferential reinforcement, σ1 is the radial restraint stress of the circular section, and k e For effective constraint coefficients, P sv For the volumetric stirrup ratio of the circumferential reinforcement, σ yh For the yield strength of the circumferential reinforcement, d sLet be the diameter of the cross-section of the column surrounded by the circumferential reinforcement. Column 1, with the addition of circumferential reinforcement 3, exhibits significantly higher axial compressive bearing capacity than the same type of column without circumferential reinforcement 3. Therefore, it is considered that during the static load-bearing process of column 1, the circumferential reinforcement 3 provides horizontal constraint to the support structure formed by the column filling material and enhances the axial bearing capacity of the support structure. To obtain the true axial compressive strength of column 1, the axial compressive strength σ of the specimen obtained from the axial compressive test needs to be corrected. In the elastic stress stage, the support structure can be considered as plain concrete or mortar. Each circumferential reinforcement 3, spaced apart, provides uneven constraint to the interior of the support structure. The effective constraint coefficient k... e To represent the effective constraint situation of circumferential reinforcement 3, k e This is the ratio of the effective confined area of ​​the cross-section of the support between adjacent circumferential ribs 3 to the area of ​​the core area of ​​the support. Comparative experiments show that the corrected axial compressive strength σ is based on the axial compressive strength σ of the test block. c The calculation error between the axial compressive strength of the scaled-down specimen and the simulated circumferential reinforcement 3 constraint effect does not exceed 5%. This technical solution can further accurately obtain the bearing capacity of a single support column 1. Optionally, in the design, the axial compressive strength σ of the same material specimen of support column 1 can also be directly used to calculate the bearing capacity of a single support column 1, and the constraint lifting effect of circumferential reinforcement 3 is used as the design redundancy of bearing capacity.

[0040] In another technical solution, S3 also includes: S4. Based on the calculation results obtained in S3, support pillar 1 is arranged in the first mining roadway, and monitoring points are set up to monitor the support pillar pressure in real time. Specifically, the monitoring equipment used to monitor the support pillar pressure can be a hydraulic pillow, or other monitoring equipment that can accurately record the stress and strain of the support pillar can be used. The observation begins within a range of 40 to 80m from the working face and ends when the working face is mined to the location of the monitoring point.

[0041] S5. Based on the prop pressure variation pattern obtained in S4, recalculate the prop construction parameters. Specifically, based on the obtained detection data, optimize the design of the goaf roadway in the subsequent mining phase. In the mining roadway in the first mining phase, the support effect of prop 1 is good. When the measured data shows that the force on prop 1 is small, the calculation results of the mining roadway in the subsequent mining phase can be appropriately optimized, and the total number of props 1 can be appropriately reduced to reduce the overall cost. When the collected data shows that the force on the prop is much greater than the design value, the construction parameters of prop 1 in the subsequent mining roadway are recalculated based on the collected values ​​to ensure the support safety of the mining roadway.

[0042] S6. Arrange supports in the subsequent mining roadway based on the calculation results of S5.

[0043] In another technical solution, a hydraulic bolster is used to monitor the support column pressure. The hydraulic bolster has significant advantages in monitoring the axial pressure of support column 1, including high-precision measurement, uniform loading, real-time monitoring, ease of operation, and high safety. It can accurately feed back pressure data, simulate actual working conditions, avoid localized stress concentration, and record pressure changes in real time through a data acquisition system, providing a reliable basis for the mechanical performance analysis of support column 1.

[0044] In another technical solution, the diameter of the hydraulic cushion is equal to the diameter of the support column 1. A hydraulic cushion of the same diameter can completely cover the end face of the support column 1, ensuring uniform distribution of axial pressure and avoiding stress concentration or edge effects, thereby more realistically simulating the actual stress state. At the same time, maximizing the contact area improves measurement accuracy, reduces pressure loss and errors, and makes the monitoring results more representative. A hydraulic cushion of the same diameter can more scientifically and efficiently detect the axial compression performance of the support column and provide accurate data support.

[0045] The following are specific on-site examples: Taking the 13218 longwall face of XJH Coal Mine as an example, the 13218 longwall face adopts a single-strike longwall mining method, integrated mechanized mining technology, and full caving method to treat the goaf. During the excavation of the 13218 longwall face's haulage roadway, auxiliary haulage roadway, return airway, and connecting roadway, all are excavated along the coal seam floor. The roadway shape is rectangular. The 13218 return airway has a height of 3.8m and a width of 5.3m. The roof support design drawing for the 13218 return airway is shown below. Figure 4 As shown, steel strands with a diameter of Φ21.6mm and a length of 6000mm are used as anchor cables, arranged in a 2×2 configuration with a spacing of 3000mm×2700mm between rows. Based on the calculation of the working face support strength and the mine pressure observation data of adjacent working faces, the ZY15000 / 28 / 58D hydraulic support is selected as the working face support equipment. The design value of the hydraulic support support strength is 1MPa. The 13218 return airway is designed with flexible mold pump props for advance support. A relatively independent section of the 13218 return airway is selected as a calculation example, with a length of 105m.

[0046] The specific steps in the design method of flexible mold pumped prop support system for impact environments include: The unit weight of the roof rock mass in return airways S1 and 13218 is 2.56 × 9.8 kN / m³. 3 The support filling material is prepared with a water-cement ratio of 1:1. The axial compression test strength σ of the same material test block after 28 days of curing is 15MPa. Considering the space requirements for mechanical transportation and construction in the 13218 return airway, the diameter of the support needs to be controlled between 700mm and 1100mm. The circumferential reinforcement on the filling bag used in the design is HPB235 steel bar with a diameter of 10mm and a spacing of 200mm. Four identical specimens of the same size and material, with a height-to-diameter ratio of 3.8m, were fabricated. The diameters of the four specimens were 700mm, 800mm, 900mm, and 1000mm, respectively. Axial compression tests were performed on the four specimens sequentially, and the relative increase in bearing capacity curves were plotted as follows: Figure 5 As shown, 800 mm, corresponding to the maximum relative increase in bearing capacity, is selected as the column diameter. The effective constraint coefficient k of the ring reinforcement on the column for the support body is... e =0.765, volumetric stirrup ratio P sv =0.0079, yield strength σ of circumferential reinforcement yh =235 MPa, radial constraint stress of circular cross section σ1=0.711 MPa, corrected axial compressive strength σ c =19.43 MPa. In this calculation example, to retain a certain design redundancy in bearing capacity, the axial compression test strength of the test block of 15 MPa is still used for subsequent calculations of the bearing capacity of a single column; the design value of the bearing capacity P of a single column is... a The calculation formula is: Among them, the structural strength Guggen coefficient f s The value is 0.97; Calculate the design number N of supports under the most unfavorable top slab load condition. In this calculation section, the anchor cable spacing is 3m, with 2 cables per row. The anchoring force of the anchor cables is 180KN, and the anchoring force weakening factor f is taken as 0.66. The calculation formula is as follows: This calculation section adopts a double-row support design, with a total number of supports rounded up to 46. The support area S of a single support on the roadway roof is 12.10㎡. The support locations are as follows: Figure 7 As shown, two supports are arranged in a row with a row spacing of 4.77m. To facilitate personnel passage and equipment transportation, the distance between the support axis and the nearby alleyway side is set at 0.9m, and the distance between the supports axis in the same row is 3.5m.

[0047] S2. Prepare multiple cylindrical impact test blocks with dimensions Ф50mm×50mm. Each impact test block is covered with a filler bag. The impact test blocks are then placed sequentially in a Hopkinson bar testing system and subjected to impact tests at different impact velocities. The test results show that at an impact velocity of 10.16 m / s, the filler bag of the corresponding impact test block remains intact, but axial cracks appear in the filling material of the internal pumping strut, along with circumferential cracks at a certain angle to the axial cracks. Multiple cracks show a tendency to penetrate each other. The stress wave curve of this impact test block at this time is as follows: Figure 6 As shown, the corresponding transmitted wave intensity σ' t The dynamic strength of the impact test block is 32.67 MPa. In step S1, the diameter of the support column is 800 mm and the height is 3.8 m. The dynamic strength of the test block needs to be corrected to obtain the dynamic load strength of the support column. The calculation formula is as follows: Dynamic load support strength .

[0048] S3. Obtain the hydraulic support strength q on the working surface. t =1 MPa, dynamic load support strength q of the calculated section of the 13218 return airway a >q t It can be assumed that the parameters of the flexible mold pumping support based on static load design meet the requirements of dynamic load calculation, which can ensure the stability of the support under pressure. In the calculation section of return airway 13218, 46 supports are evenly spaced. The design positions of the supports are as follows: Figure 7 As shown, the bearing capacity requirements of the top plate of this calculation section for both static and dynamic loads can be met.

[0049] S4. Based on the above design results, several large hydraulic pillows with the same diameter as the support pillars will be fabricated and customized on site. These pillows will be installed at the bottom of the pumping support pillars at the designed locations to monitor the support pillar resistance in real time. The pillows will be positioned in the first mining roadway. Figure 7 As shown, monitoring data is collected as the working face advances.

[0050] S5, the collected data is as follows Figure 7 As shown, the pressure values ​​at distances of 62m, 45m, and 27m from the monitoring point are 0.2MPa, 0.4MPa, and 2.8MPa, respectively. The highest value of 3.4MPa is reached at a distance of 22m from the monitoring point. After that, the value at the monitoring point gradually decreases as the working face advances. The support performance is excellent during the overall stress process. According to the monitoring results, the advance support range of the working face is considered to be 40m. According to the field monitoring results, the actual maximum bearing pressure of a single column is 1708KN, which is 2.7% different from the design bearing capacity of 1662.4KN for a single column in the previous steps. There were no cases where the actual monitoring data was too low or too high as the design value. This indicates that the support size and spacing adopted according to the design method can effectively achieve the support effect while controlling the number of columns. This design parameter can continue to be used in the subsequent mining roadways.

[0051] It should be noted that although the steps are described in a specific order above, this does not mean that they must be performed in that order. In fact, some of these steps can be executed concurrently, or even in a different order, as long as the required functionality is achieved. The number of devices and processing scale described herein are for simplification of the invention; applications, modifications, and variations of this invention will be readily apparent to those skilled in the art.

[0052] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A design method for a flexible mold pumping support system in impact environments, characterized in that, Includes the following steps: S1. Obtain the support design parameters under static load: Obtain the size information of the mining roadway, the surrounding rock information of the mining roadway, and the anchoring design information of the mining roadway within the mining area of ​​the working face, and complete the support design under the load of the roadway roof. The design results include the support height h, the support diameter w, the number of supports N, and the support area S of a single support on the roadway roof. S2. Obtain the dynamic load support strength of the support column: Impact test blocks are fabricated using the same material as the support column, and impact tests are conducted on the impact test blocks to obtain the dynamic load strength σ of the support column. t And the dynamic load support strength q of the support column on the roadway roof. a The formula for calculating the dynamic load support strength is as follows: ; S3. Correct the support column design parameters under impact conditions: Obtain the hydraulic support strength q on the working surface. a If q a >q t If the design results meet the dynamic load support requirements of the longwall mining roadway, then q a ≤q t If so, the number of support pillars should be increased; The support includes a filling bag and a plurality of circumferential ribs spaced apart on the inner surface of the filling bag, wherein the support filling material fills and solidifies inside the filling bag to form a support body; The surrounding rock information of the mining roadway includes the rock mass unit weight γ, the roadway caving width B, and the roadway caving height H. The anchoring design information of the mining roadway includes the anchor cable spacing a, the anchor cable anchoring force p', the number of anchor cables per row n, and the roadway support length L. The support design under the roof load includes the following steps: A1. Determine the support diameter w based on the dimensions of the mining roadway and the working space requirements; A2. Calculate the design value p of the bearing capacity of a single support column. a The calculation formula is: Where σ is the axial compression test strength of the support and the same material specimen, f s The structural strength coefficient is the Goohl coefficient, with a value ranging from 0.9 to 1. A3. Calculate the design number N of supports under the most unfavorable top slab load condition. The calculation formula is as follows: , where f is the anchoring force weakening coefficient; A4. Calculate the support area S of a single support pillar on the tunnel roof.

2. The design method for a flexible mold pumping support system for impact environments as described in claim 1, characterized in that, S2 includes the following steps: S21. Using the same material as the support column, make multiple cylindrical impact-resistant test blocks with dimensions of Ф50mm×50mm; S22. Using the Hopkinson bar test system, impact the impact test blocks one by one at different impact velocities and record the data, including the transmitted wave intensity σ' corresponding to each test. t ; S23. Observe the damage of the impact-resistant test blocks under different impact velocities, and use the transmitted wave intensity σ' corresponding to the impact-resistant test block when a through crack is about to appear. t As the dynamic strength of the test block; S24. Based on the height-to-diameter ratio of a single support column in the support column design results, the dynamic strength of the test block is corrected to obtain the dynamic load strength σ. t And obtain the dynamic load support strength q a .

3. The design method for a flexible mold pumping support system for impact environments as described in claim 1, characterized in that, A1 includes the following steps: A11. Using the same material as the support column, multiple sets of height-to-diameter ratio specimens with varying height-to-diameter ratios from low to high were produced. A12. Apply axial compression to the high-to-diameter ratio specimens sequentially from high to low and record the compressive strength and the relative increase in the bearing capacity of the specimens with the previous high-to-diameter ratio specimens. Obtain the high-to-diameter ratio specimen with the maximum relative increase in bearing capacity. A13. The height-to-diameter ratio of the test block with the largest relative increase in bearing capacity is taken as the design height-to-diameter ratio of the support. The height of the support is h, and the diameter w of the support is calculated.

4. The design method for a flexible mold pumping support system for impact environments as described in claim 3, characterized in that, The calculation formula for correcting the dynamic strength of the test block is as follows: .

5. The design method for a flexible mold pumping support system for impact environments as described in claim 1, characterized in that, S3 also includes: S4. Based on the calculation results obtained in S3, the props are arranged in the mining roadway where the first mining is carried out, and monitoring points are set up to monitor the prop pressure in real time. S5. Based on the column pressure variation pattern obtained in S4, recalculate the column construction parameters; S6. Arrange supports in the subsequent mining roadway based on the calculation results of S5.

6. The design method for a flexible mold pumping support system for impact environments as described in claim 5, characterized in that, Hydraulic pillows are used to monitor the support column pressure.

7. The design method for a flexible mold pumping support system for impact environments as described in claim 6, characterized in that, The diameter of the hydraulic pillow is equal to the diameter of the support column.

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