Experimental method for supporting parameter design of pile foundation hydraulic support

Abstract

The invention relates to an experimental method for supporting parameter design of a pile foundation hydraulic support. The experimental method for supporting parameter design of the pile foundation hydraulic support comprises the following steps of (1) designing a support-bottom pile-surrounding rock system experimental model, (2) building an experimental system, (3) performing an experiment, and (4) analyzing an experimental result. According to the method, the plane strain theory of mechanics is adopted, a digital image correlation method is used for direct observation, and an experimental basis is provided for pile foundation hydraulic support supporting parameter design; and a bracket-bottom pile-surrounding rock interaction mechanism and a control mechanism of a bottom pile and bracket coupling effect on surrounding rock expansion, bottom heaving and damage are disclosed. By changing specific geology and mining parameters of a coal mine, pile foundation hydraulic support supporting design parameters under different surrounding rock conditions are finally obtained.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation hydraulic support support, in particular to an experimental method for pile foundation hydraulic support support parameter design. Background Art

[0002] The support form of pile foundation hydraulic support is fundamentally different from that of anchor rods (cables) and traditional supports in terms of support principle. There are still many problems that have not been answered by current theories in terms of the interaction between support and surrounding rock, especially the displacement, deformation and stress evolution characteristics of the support, bottom pile and tunnel surrounding rock under load. Therefore, through in-depth and meticulous experimental research on the interaction between pile foundation hydraulic support and surrounding rock, the interaction mechanism of support-bottom pile-surrounding rock can be revealed, so as to design scientific and reasonable support equipment that can effectively control the expansion, bottom drum and destruction of surrounding rock. At present, in the experimental research on the interaction between support and surrounding rock, the plane stress model (tunnel thickness is about 0.2m) is mainly used, anchor rods (cables) or supports are arranged in the tunnel, and support and surrounding rock stress monitoring are carried out through strain gauges. This plane stress model has the following three disadvantages: Disadvantage 1: The boundary effect of the model causes errors in the experimental results; Disadvantage 2: The discontinuous distribution of anchor rods (cables) or brackets causes mutual influence between the support structures, which affects the accuracy of the design of the interaction parameters between the surrounding rock and the support; Disadvantage 3: During the laying of similar materials to simulate the rock formation, strain gauges are buried in the surrounding rock to monitor the surrounding rock stress; however, the buried strain gauges are not sensitive to the slight deformation of the surrounding rock, and the test accuracy is inaccurate. Summary of the invention

[0003] The purpose of the present invention is to solve the above problems and to provide an experimental method for designing support parameters of a pile foundation hydraulic support.

[0004] The technical solution of the present invention is: an experimental method for designing support parameters of a pile foundation hydraulic support, comprising the following steps: ① Design the experimental model of the support-bottom pile-surrounding rock system According to the specific geological and mining parameters of the coal mine, the size parameters of the experimental model and the simulation support are determined by similarity ratio calculation; the experimental model includes a bottom plate, coal seam similar materials and a top plate from bottom to top; the bottom plate and the top plate are paved with rock layer similar materials; an experimental simulation roadway is set at the bottom of the coal seam similar materials; a number of simulation supports are evenly distributed axially in the experimental simulation roadway; the simulation support includes a steel top beam, a column and a bottom pile; the simulation support simulates a pile foundation hydraulic support; because the hydraulic cylinder of the pile foundation hydraulic support will no longer expand and contract after it is determined to support the top of the roadway, the processing can be simplified here, and the top of the column is directly connected symmetrically to the two ends of the top beam; the bottom end of the column is hinged to the top of the bottom pile; the bottom pile is inserted into the bottom plate; the experimental model simulates the surrounding rock of the roadway supported by the pile foundation hydraulic support; ②Build an experimental system Lay rock-like materials on the test bench to form a bottom plate; lay coal-like materials layer by layer on the top of the bottom plate; use metal partitions to vertically separate the simulated tunnel area when laying coal-like materials layer by layer; when the coal-like materials laid layer by layer approach the top of the metal partition, set up a simulated bracket in the experimental simulated tunnel area; install strain gauges on the top beam, columns and bottom piles; insert the bottom piles into the bottom plate; the strain gauges are used to detect the stress and deformation of the top beam, columns and bottom piles; the detection data of the strain gauges are different currents, not It can directly reflect the stress and deformation of the top beam, columns and bottom piles; the detection data of the strain gauge is converted by the strain gauge into data that can directly reflect the stress and deformation of the top beam, columns and bottom piles; the simulated tunnel area is horizontally separated by a metal partition; after the coal seam similar material is laid layer by layer to a certain thickness, the rock stratum similar material is laid layer by layer to form the roof; the speckle is sprayed within a certain range around the end face of the experimental model tunnel to produce a speckle surface; the speckle surface is conducive to the rock stratum similar material simulating the surrounding rock to be photographed by the CCD camera for tiny deformation; ③ Conduct experiments Pull out the metal partition; apply static load on the top plate; use CCD camera to capture speckle images; use strain gauge to collect strain data of columns, top beams and bottom piles; prepare for subsequent experimental results analysis; ④Analysis of experimental results The digital speckle correlation method is used to analyze the experimental speckle images collected by the CCD camera, and the displacement field, deformation field and energy field of the experimental model during static loading are calculated. The force and deformation characteristics of the bottom pile under the support load are studied, and the evolution law of the support displacement and the deformation of the experimental model is analyzed. The influence of the bottom pile on the stress, displacement and deformation of the surrounding rock is studied, and the influence of the bottom pile on the stress distribution of the support is studied.

[0005] The above method can simulate the support situation of pile foundation hydraulic support under different surrounding rock conditions, analyze the deformation evolution law of surrounding rock with digital speckle pattern, and monitor the support deformation data with strain gauge, so as to provide a basis for the support design parameters.

[0006] Preferably, in step ①, the top beam includes a left beam body and a right beam body; the left end of the left beam body and the right end of the right beam body are both connected to the top end of the column; the right end of the left beam body and the left end of the right beam body are hinged to each other.

[0007] Preferably, in step ①, baffles extend upward from both ends of the top of the experimental table; the experimental model is set between the two baffles; the baffles constrain the experimental model to ensure that the experimental model can fill the space between the top plate and the bottom plate to simulate the real tunnel surrounding rock environment.

[0008] Preferably, the static load in step ③ is a weight, which is a standard weight with high precision, facilitating the analysis and calculation in the subsequent step ④.

[0009] Preferably, in step ③, the speckle image data obtained by the CCD camera and the data collected by the strain gauge are transmitted to the computer; in step ④, the computer completes the analysis of the experimental results; the computer replaces manual analysis of the experimental results, which not only ensures the accuracy of the calculation results, but also improves the calculation speed.

[0010] Furthermore, in step ③, the strain gauge outputs an electrical signal to the data converter; the data converter outputs a data signal to the computer; this can reduce the process of manually inputting strain gauge detection data and improve experimental efficiency.

[0011] Preferably, in step ①, the column is a micro cylinder to better fit the actual situation of the pile foundation hydraulic support.

[0012] Preferably, in step ②, the axial length of the experimental simulation tunnel is ≥ 4 times the larger of the length and width of the experimental simulation tunnel, so as to be closer to the actual tunnel surrounding rock conditions.

[0013] The beneficial effects of the present invention are as follows: the experimental method for designing support parameters of a pile foundation hydraulic support of the present invention has the following advantages: (1) The present invention adopts the plane strain theory of mechanics and uses the digital image correlation method for direct observation to provide an experimental basis for the design of support parameters for pile foundation hydraulic support; it reveals the interaction mechanism between support, bottom pile and surrounding rock and the control mechanism of the coupling effect of bottom pile and support on the expansion, bottom drum and destruction of surrounding rock. Finally, the design parameters of pile foundation hydraulic support support under different surrounding rock conditions are obtained; (2) The present invention uses computers to replace manual analysis of experimental results, which not only ensures the accuracy of the calculation results but also improves the calculation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a three-dimensional diagram of the present invention after forming an experimental model on a test bench; Figure 2 yes Figure 1 A vertical cross-sectional view of Figure 3 It is a working principle diagram of the present invention; Figure 4 It is to make a real picture of the object in front of the speckle; Figure 5 It is the actual picture after making the speckle surface; Figure 6 yes Figure 5 A partial map of Figure 7 yes Figure 5 's vision; Figure 8 is the diagram after static load is applied; Fig. 9It is the cloud image obtained by speckle image analysis; In the figure: 1. experimental table, 11. baffle, 111. adjusting screw hole, 2. coal seam similar material, 21. experimental simulation tunnel, 31. roof, 32. bottom plate, 4. simulation support, 411. left beam, 412. right beam, 42. column, 43. bottom pile, 5. weight, 6. CCD camera, 7. strain gauge, 8. computer, 91. pressure plate, 92. limit plate. DETAILED DESCRIPTION

[0015] Example 1: See Figure 1-3 , an experimental method for designing support parameters of pile foundation hydraulic support, comprising the following steps: ① Design the experimental model of the support-bottom pile 43-surrounding rock system According to the specific geological and mining parameters of the coal mine, the size parameters of the experimental model and the simulation support 4 are determined by similarity ratio calculation; the experimental model includes a bottom plate 32, a coal seam similar material 2 and a top plate 31 from bottom to top; the bottom plate 32 and the top plate 31 are both paved with rock layer similar materials; an experimental simulation tunnel 21 is arranged at the bottom of the coal seam similar material 2; a number of simulation supports 4 are evenly distributed axially in the experimental simulation tunnel 21; the simulation support 4 includes a steel top beam, a column 42 and a bottom pile 43; the simulation support 4 simulates a pile foundation hydraulic support; because the hydraulic cylinder of the pile foundation hydraulic support will no longer expand and contract after determining that the top of the tunnel is supported, the processing can be simplified here, and the top of the column 42 is directly connected symmetrically to the two ends of the top beam; the bottom end of the column 42 is hinged to the top of the bottom pile 43; the bottom pile 43 is inserted into the bottom plate 32; the experimental model simulates the tunnel surrounding rock supported by the pile foundation hydraulic support; ②Build an experimental system A rock-like material is laid on the test bench 1 to form a bottom plate 32; a coal-like material 2 is laid layer by layer on the top of the bottom plate 32; when the coal-like material 2 is laid layer by layer, a metal partition is used to vertically separate the simulated tunnel area; when the layered coal-like material 2 approaches the top of the metal partition, a simulated bracket 4 is set in the experimental simulated tunnel 21 area; a strain gauge is installed on the top beam, the column 42 and the bottom pile 43; the bottom pile 43 is inserted into the bottom plate 32; the strain gauge is used to detect the stress deformation of the top beam, the column 42 and the bottom pile 43; the detection data of the strain gauge is different in size. Small current cannot directly reflect the stress and deformation of the top beam, the column 42 and the bottom pile 43; the detection data of the strain gauge is converted by the strain gauge 7 into data that can directly reflect the stress and deformation of the top beam, the column 42 and the bottom pile 43; a metal partition is used to horizontally separate the simulated tunnel area; after the coal seam similar material 2 is laid layer by layer to reach a certain thickness, the rock layer similar material is laid layer by layer to form the roof 31; the speckle is sprayed within a certain range around the experimental model tunnel to produce a speckle surface; the speckle surface is conducive to the rock layer similar material simulating the surrounding rock being photographed by the CCD camera 6 to detect the slight deformation; ③ Conduct experiments Pull out the metal partition; apply a static load on the top plate 31; use the CCD camera 6 to capture the speckle image; use the strain gauge 7 to collect the strain data of the column 42, the top beam and the bottom pile 43; prepare for the subsequent experimental result analysis; ④Analysis of experimental results The digital speckle correlation method is used to analyze the experimental speckle images collected by the CCD camera 6, and the displacement field, deformation field and energy field of the experimental model during static load loading are calculated. The force and deformation characteristics of the bottom pile 43 under the support load are studied, the evolution law of the support displacement and the deformation of the experimental model is analyzed, the influence of the bottom pile 43 on the stress, displacement and deformation of the surrounding rock is studied, and the influence of the bottom pile 43 on the support stress distribution is studied; the interaction mechanism of the support-bottom pile 43-surrounding rock and the control mechanism of the coupling effect of the bottom pile 43 and the support on the expansion, bottom drum and destruction of the surrounding rock are revealed.

[0016] The above method is used to simulate the support conditions of pile foundation hydraulic support under different surrounding rock conditions, digital speckle analysis is used to analyze the deformation evolution law of surrounding rock, and strain gauges are used to monitor the support deformation data, providing a basis for the support design parameters.

[0017] Compared with the prior art, the present invention adopts the plane strain theory of mechanics and directly observes with the digital image correlation method, providing an experimental basis for the design of support parameters of pile foundation hydraulic support; revealing the interaction mechanism of support-bottom pile 43-surrounding rock and the control mechanism of the coupling effect of bottom pile 43 and support on the expansion, bottom drum and destruction of surrounding rock. By changing the specific geological and mining parameters of the coal mine, the design parameters of pile foundation hydraulic support support under different surrounding rock conditions are finally obtained.

[0018] In step ①, the top beam includes a left beam body 411 and a right beam body 412; the left end of the left beam body 411 and the right end of the right beam body 412 are both connected to the top of the column 42; the right end of the left beam body 411 and the left end of the right beam body 412 are hinged to each other.

[0019] In step ①, baffles 11 extend upward from both ends of the top of the experimental platform 1; the experimental model is set between the two baffles 11; the baffles 11 constrain the experimental model to ensure that the experimental model can fill the space between the top plate 31 and the bottom plate 32 to simulate the real tunnel surrounding rock environment.

[0020] In step ②, a pressing plate 91 is placed on the top of the test model; the static load can be uniformly applied to the test model through the pressing plate 91 .

[0021] The baffle 11 has a plurality of adjustment screw holes 111 in an array on the end face; the limit plates 92 are symmetrically installed at the front and rear ends of the baffle 11; the two ends of the limit plates 92 are connected to the adjustment screw holes 111 through screws; the limit plates 92 can limit the flow of coal seam similar materials 2 and rock formation similar materials until they solidify and form an experimental model.

[0022] The static load in step ③ is weight 5, which is a standard weight with high precision, and is convenient for analysis and calculation in the subsequent step ④.

[0023] In step ③, the speckle image data obtained by the CCD camera 6 and the data collected by the strain gauge 7 are transmitted to the computer 8; in step ④, the computer 8 completes the analysis of the experimental results; the computer 8 replaces manual analysis of the experimental results, which not only ensures the accuracy of the calculation results, but also improves the calculation speed.

[0024] In step ③, the strain gauge outputs an electrical signal to the data converter; the data converter outputs a data signal to the computer 8; this can reduce the process of manually inputting the strain gauge 7 detection data and improve the experimental efficiency.

[0025] Working principle of this embodiment: The present invention adopts the plane strain theory of mechanics and directly observes with the digital image correlation method to provide an experimental basis for the design of support parameters of pile foundation hydraulic support; it reveals the interaction mechanism of support-bottom pile 43-surrounding rock and the control mechanism of the coupling effect of bottom pile 43 and support on surrounding rock expansion, bottom drum and destruction. By changing the specific geological and mining parameters of the coal mine, the design parameters of pile foundation hydraulic support support under different surrounding rock conditions are finally obtained.

[0026] Embodiment 2: Embodiment 2 is basically the same as Embodiment 1, and the similarities are not repeated here. The difference is that in step ①, the column 42 is a micro cylinder to better fit the actual situation of the pile foundation hydraulic support.

[0027] In step ②, the axial length of the experimental simulation tunnel 21 is ≥ 4 times the larger of the length and width of the experimental simulation tunnel 21 to be closer to the actual tunnel surrounding rock conditions.

Claims

1. An experimental method for designing support parameters of pile foundation hydraulic support, characterized in that: The following steps are involved: ① Design the experimental model of the support-bottom pile-surrounding rock system According to the specific geological and mining parameters of the coal mine, the size parameters of the experimental model and the simulation support are determined by similarity ratio calculation; the experimental model includes a bottom plate, a coal seam similar material and a top plate from bottom to top; the bottom plate and the top plate are both paved with rock layer similar materials; an experimental simulation roadway is set at the bottom of the coal seam similar material; a number of simulation supports are evenly distributed axially in the experimental simulation roadway; the simulation support includes a steel top beam, a column and a bottom pile; the top of the column is symmetrically connected to the two ends of the top beam; the bottom end of the column is hinged to the top of the bottom pile; the bottom pile is inserted into the bottom plate; ②Build an experimental system Lay rock-like materials on the test bench to form a bottom plate; lay coal-like materials layer by layer on the top of the bottom plate; use metal partitions to vertically separate the simulated tunnel area when laying coal-like materials layer by layer; set up simulation brackets in the experimental simulated tunnel area when the coal-like materials laid layer by layer are close to the top of the metal partition; install strain gauges on the top beam, columns and bottom piles; insert the bottom piles into the bottom plate; use metal partitions to horizontally separate the simulated tunnel area; after the coal-like materials are laid layer by layer to a certain thickness, lay rock-like materials layer by layer to form a top plate; Spraying speckles in a certain range around the end face of the experimental model tunnel to produce a speckle surface; ③ Conduct experiments Pull out the metal partition; apply static load on the top plate; use a CCD camera to capture speckle images; use strain gauges to collect strain data on the columns, top beams, and bottom piles; ④Analysis of experimental results The digital speckle correlation method is used to analyze the experimental speckle images collected by the CCD camera, and the displacement field, deformation field and energy field of the experimental model during static loading are calculated. The force and deformation characteristics of the bottom pile under the support load are studied, and the evolution law of the support displacement and the deformation of the experimental model is analyzed. The influence of the bottom pile on the stress, displacement and deformation of the surrounding rock is studied, and the influence of the bottom pile on the stress distribution of the support is studied.

2. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1 is characterized in that: In step ①, the top beam includes a left beam body and a right beam body; the left end of the left beam body and the right end of the right beam body are both connected to the top of the column; the right end of the left beam body and the left end of the right beam body are hinged to each other.

3. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1 is characterized in that: In step ①, baffles are extended upward from both ends of the top of the experimental table; and the experimental model is set between the two baffles.

4. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1 is characterized in that: The static load in step ③ is the weight.

5. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1, characterized in that: In step ③, the speckle image data obtained by the CCD camera and the data collected by the strain gauge are transmitted to the computer; in step ④, the computer completes the analysis of the experimental results.

6. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1, characterized in that: In step ①, the column is a micro cylinder.

7. The experimental method for designing support parameters of pile foundation hydraulic support according to claim 1, characterized in that: In step ②, the axial length of the experimental simulation tunnel is ≥ 4 times the larger of the length and width of the experimental simulation tunnel.

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