Flexible protective net multi-angle impact resistance test platform, design method and test method

Abstract

The invention discloses a flexible protective net multi-angle impact resistance test platform, a design method and a test method, and belongs to the field of flexible protective net performance tests.The flexible protective net multi-angle impact resistance test platform comprises two oppositely-arranged reaction walls, a flexible protective net arranged between the two reaction walls, hoisting equipment arranged above the flexible protective net and a monitoring analysis mechanism; a plurality of positioning holes arranged in a rectangular array are formed in the opposite sides of the two reaction walls, and the positioning holes in the two reaction walls are aligned one by one in the horizontal direction; the flexible protective net is composed of transverse steel strands and longitudinal steel strands, and the two ends of the longitudinal steel strands penetrate through the positioning holes in the two reaction walls respectively and then are fixed to the ground through ground anchors. By adopting the multi-angle impact resistance test platform for the flexible protective net, the design method and the test method, a vertical impact test or an inclined impact test can be carried out on the flexible protective net by utilizing the scientifically designed test platform, and the use is more flexible.

Description

Technical Field

[0001] The invention relates to the technical field of flexible protection net performance testing, and in particular to a flexible protection net multi-angle impact resistance testing platform, a design method and a testing method. Background Art

[0002] Flexible protection nets, also often called slope protection nets or SNS active protection systems, are designed to stabilize slopes and prevent natural disasters such as rock falls and soil erosion.

[0003] In order to ensure the performance of the flexible protective net, it is necessary to conduct an impact test on the flexible protective net before leaving the factory or before construction. The impact test simulates the impact force of natural phenomena such as sudden rockfall and soil sliding that may be encountered in actual applications on the protective net. Through the test, it can be verified whether the structural strength, energy absorption capacity and overall stability of the flexible protective net meet the design requirements, ensuring that it can effectively protect and ensure the safety of people and property below.

[0004] The existing impact test technologies for flexible protective nets are as follows: CN202410701769.X discloses an impact test device for a railway flexible protective net, which includes an impact test base, an impact test vertical plate fixedly connected to the rear of the upper end surface of the impact test base, a top plate slidably connected to the inner cavity of the impact test vertical plate, a buffer frame fixedly connected to the left and right sides of the front of the upper end surface of the impact test base, a mounting frame fixedly connected to the left and right sides of the middle of the front end surface of the impact test vertical plate, a protective net installed between the two mounting frames; a lifting mechanism, a lifting mechanism is provided on the rear end surface of the impact test vertical plate; a clamping mechanism; a buffer mechanism; and a protective mechanism.

[0005] It can be seen that general impact tests of flexible protective nets are mostly carried out in test environments, which cannot simulate the actual working environment of the flexible protective net and have poor reliability.

[0006] Some of the impact test technologies for flexible protective nets that simulate real rockfall impacts are as follows: CN201811074124.9 discloses a large-scale integrated platform that can be used for full-scale impact tests of various flexible protective structures, which includes a reaction wall and a detachable construction platform for installing a passive flexible protective net test model and a curtain net test model, an anchor trench for installing a flexible shed tunnel test model, a lifting device for lifting and releasing an impact test block and an impact slider, a slideway and slideway support for providing a horizontal impact speed for the impact slider, an observation platform for setting up a high-speed camera, and a junction box for burying sensor data cables.

[0007] It can be seen that it can only perform tests at specific angles, not multi-angle tests, and the test platform is not designed according to actual conditions. It needs to be debugged repeatedly before testing, which increases the test time cost. Summary of the invention

[0008] The purpose of the present invention is to provide a flexible protective net multi-angle impact resistance test platform, design method and test method to solve the above technical problems.

[0009] To achieve the above-mentioned purpose, the present invention provides a flexible protective net multi-angle impact resistance test platform, comprising two oppositely arranged reaction walls, a flexible protective net arranged between the two reaction walls, a lifting device arranged above the flexible protective net, and a monitoring and analysis mechanism for monitoring the state parameters of the flexible protective net under the impact of falling rocks released by the lifting device; A plurality of positioning holes arranged in a rectangular array are provided on opposite sides of the two reaction walls, and the plurality of positioning holes on the two reaction walls are aligned one by one in the horizontal direction; The flexible protective net is composed of transverse steel strands and longitudinal steel strands arranged in a criss-cross pattern. The intersections of the transverse steel strands and the longitudinal steel strands are fixed by buckles. The two ends of the longitudinal steel strands pass through the positioning holes on the two reaction walls and are fixed to the ground by ground anchors.

[0010] Preferably, when the two ends of the longitudinal steel strand pass through two positioning holes located at the same height respectively, it is used to perform a rockfall vertical impact test.

[0011] Preferably, when the two ends of the longitudinal steel strand pass through two positioning holes located at different heights respectively, it is used to perform a rockfall inclined impact test.

[0012] Preferably, the monitoring and analysis mechanism includes a contact monitoring component, a non-contact monitoring component, a data collector and a host computer. The contact monitoring component is connected to the host computer via the data collector, and the host computer is also connected to the non-contact monitoring component. The host computer is equipped with a DHDAS software platform for outputting performance test results of the flexible protective net based on state change parameters of the flexible protective net under rockfall impact collected by the contact monitoring component and the non-contact monitoring component.

[0013] Preferably, the contact monitoring assembly comprises: Multiple force sensors, which are installed at the connection point between the end of the transverse steel strand and the ground anchor or the connection point between the end of the longitudinal steel strand and the ground anchor, and are used to collect the force of each transverse steel strand and the force of each longitudinal steel strand when the falling rock impacts the flexible protection net; A plurality of strain rosettes are installed at a plurality of buckles arranged in a radial shape from the center of the flexible protection net, and are used to collect strains of the plurality of buckles radiating from the center to the outside when falling rocks impact the flexible protection net; A plurality of pull-wire sensors are installed at a plurality of buckles arranged in a radial shape at the center of the flexible protection net, and are used to collect the displacement of the plurality of buckles radiating from the center to the outside when falling rocks impact the flexible protection net; A plurality of three-dimensional acceleration sensors are installed at a plurality of buckles arranged in a radial shape from the center of the flexible protection net, and are used to collect the impact acceleration when the falling rock impacts the flexible protection net; A plurality of tension sensors are installed on the transverse steel strands or the longitudinal steel strands to collect the tension of the transverse steel strands or the longitudinal steel strands when falling rocks impact the flexible protective net; A plurality of displacement sensors are installed at the center of the flexible protective net and at symmetrical positions around the center of the flexible protective net, and are used to collect the displacement of the flexible protective net when falling rocks impact the flexible protective net.

[0014] Preferably, the non-contact monitoring component comprises one of a high-speed camera, a laser speckle meter, an infrared imager, and any combination thereof, and the non-contact monitoring component is aligned with the steel strand to be tested.

[0015] The design method of the flexible protective net multi-angle impact resistance test platform comprises the following steps: S1. Based on the constraint between the impact energy of the falling rock and the maximum absorbed energy of the flexible protection net, the number and length of the single steel strands constituting the flexible protection net, as well as the weight and height of the falling rock are designed; S2. Design the layout spacing of the flexible protection net based on the shape of the falling rocks; S3. Design the height of the flexible protection net based on the maximum deformation height of the flexible protection net under the impact of falling rocks; S4. Conduct test based on the designed rockfall and flexible protection net to test the stability of the test platform.

[0016] Preferably, step S1 specifically includes the following steps: S11. Consider the gravitational potential energy of the falling rock as the impact energy of the falling rock and calculate the impact energy of the falling rock: (1); In the formula, is the impact energy of the rockfall, in kJ; is the mass of the falling rock, in kg; is the acceleration due to gravity, and =9.8m / s 2 ; is the release height of the rockfall, in m; S12. Calculate the maximum absorbed energy of the flexible protective net: S121, galvanized anti-corrosion steel strands are used for both transverse and longitudinal steel strands, and the 0.2% yield strength of the steel strands is 310kN, the destructive force is 450kN, and the tensile strength is considered. Greater than 0.2% yield strength of steel strand and less than destructive force, the tensile strength of steel strand Set to 350kN; S122. Calculate the energy consumption of a single strand : (2); In the formula, represents the maximum elongation of a single strand, and , is the length of the steel strand; S123. Calculate the maximum absorbed energy of the flexible protective net : (3); In the formula, is the number of steel strands; S13. Assume that the impact energy of the falling rock is completely absorbed by the flexible protection net, and the maximum absorbed energy of the flexible protection net is equal to the gravitational potential energy of the falling rock when it is released: (4); S14. Design the number and length of single steel strands and the weight and height of falling rocks based on the constraints of formula (4).

[0017] Preferably, step S2 specifically includes the following steps: S21. Design the shape of the rockfall: simplify the 26-sided rockfall specimen into a regular hexahedron for calculation, and calculate the side length of the regular hexahedron : (5); In the formula, Indicates the speed of the falling rock when it contacts the flexible protective net; S22. Change the side length of the regular hexahedron It is regarded as the contact width between the falling rock and the flexible protective net, in meters. At the same time, the marginal effect of the falling rock impacting the flexible protective net is considered, and the width of the flexible protective net affected by the falling rock is calculated. : (6); In the formula, is a constant; S23, based on the calculation of the width of the flexible protective net affected by falling rocks , calculate the layout spacing between two adjacent steel strands in the same direction: (7); In the formula, for Layout spacing of steel strands, Direction is horizontal or vertical; In step S3, the rockfall impact drop distance is regarded as one of the right-angled sides of the right triangle and is set to , take the steel strand to be tested before impact as the other right-angled side of the right triangle, and assume that the elongation length of the steel strand to be tested after impact is equal to the maximum elongation of the steel strand, and take the elongated steel strand to be tested as the hypotenuse of the right triangle, then calculate the vertical deformation height of the flexible protective net according to the Pythagorean theorem: (8); In the formula, is the maximum descending distance of the flexible protective net under the impact of falling rocks, in meters. Deemed as the vertical deformation height of the flexible protective net; is the clear distance between two reaction walls, in m; is the elongation of a single steel strand; It is the length of the steel strand between the reaction wall and the ground anchor, in meters.

[0018] The test method of the flexible protective net multi-angle impact resistance test platform comprises the following steps: First, determine the test type and lay out the flexible protection net according to the test type: when conducting a vertical impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on the same horizontal line and then fix them to the ground through anchors; when conducting an inclined impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on different horizontal planes and then fix them to the ground through anchors; The falling rocks are then lifted to the rock release height using a lifting device and released. The rocks then fall freely until they impact the flexible protective net. During the impact, the status parameters of the flexible protective net are collected in real time with the help of a monitoring and analysis organization, and the performance test results are output.

[0019] Therefore, the present invention adopts the above-mentioned flexible protective net multi-angle impact resistance test platform, design method and test method, which has the following beneficial effects: The flexible protective net can be subjected to vertical impact test or inclined impact test by using a scientifically designed test platform. It is more flexible to use and can meet the requirements of multi-energy level testing, up to 15000kJ energy level.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a layout diagram of a rockfall vertical impact test of a multi-angle anti-impact test platform for a flexible protective net of the present invention; Figure 2 The present invention provides a layout diagram of a rockfall inclined impact test of a multi-angle anti-impact test platform for a flexible protective net.

[0022] Reference numerals 1. Falling rocks; 2. Ground anchor; 3. Reaction wall; 4. Flexible protective net; 5. Positioning hole. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "setting", "installation", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0025] like Figure 1 and Figure 2 As shown, a flexible protective net multi-angle impact resistance test platform includes two oppositely arranged reaction walls 3, a flexible protective net 4 arranged between the two reaction walls 3, a lifting device arranged above the flexible protective net 4, and a monitoring and analysis mechanism for monitoring the state parameters of the flexible protective net under the impact of falling rocks 1 released by the lifting device; a plurality of positioning holes 5 arranged in a rectangular array are opened on the opposite sides of the two reaction walls 3, and the plurality of positioning holes 5 on the two reaction walls 3 are aligned one by one in the horizontal direction; the flexible protective net 4 is composed of transverse steel strands and longitudinal steel strands arranged in a criss-cross pattern, and the intersection of the transverse steel strands and the longitudinal steel strands is fixed by buckles, and the two ends of the longitudinal steel strands pass through the positioning holes 5 on the two reaction walls 3 respectively and are fixed to the ground by ground anchors 2.

[0026] When the two ends of the longitudinal steel strand pass through the two positioning holes 5 at the same height, they are used to perform a vertical impact test of a rockfall 1. When the two ends of the longitudinal steel strand pass through the two positioning holes 5 at different heights, they are used to perform an inclined impact test of a rockfall 1. That is, in this embodiment, the flexible protective net 4 can be positioned on two positioning holes 5 at the same height or at different heights to perform a vertical impact test or an inclined impact test of a rockfall 1. Compared with the traditional test method, there is no need to change the test platform structure, which saves test time and cost and improves test efficiency.

[0027] The monitoring and analysis mechanism includes a contact monitoring component, a non-contact monitoring component, a data collector and a host computer. The contact monitoring component is connected to the host computer via the data collector, and the host computer is also connected to the non-contact monitoring component. The host computer is equipped with a DHDAS software platform, which is used to output the performance test results of the flexible protective net according to the state change parameters of the flexible protective net when impacted by falling rocks collected by the contact monitoring component and the non-contact monitoring component.

[0028] The contact monitoring component includes: a plurality of force sensors, which are installed at the connection point between the end of the transverse steel strand and the ground anchor or the connection point between the end of the longitudinal steel strand and the ground anchor, and are used to collect the force of each transverse steel strand and the force of each longitudinal steel strand when the rock falls and impacts the flexible protection net; a plurality of strain rosettes, which are installed at a plurality of buckles arranged in a radial shape at the center of the flexible protection net, and are used to collect the strain of a plurality of buckles radiating from the center to the outside when the rock falls and impact the flexible protection net; a plurality of pull rope sensors, which are installed at a plurality of buckles arranged in a radial shape at the center of the flexible protection net, and are used to collect the strain of a plurality of buckles radiating from the center to the outside when the rock falls and impact the flexible protection net. The flexible protective net is provided with a plurality of buckles radiating outward from the center thereof; a plurality of three-dimensional acceleration sensors are installed at a plurality of buckles arranged in a radial shape with the center of the flexible protective net, and are used to collect the impact acceleration when falling rocks impact the flexible protective net; a plurality of tension sensors are installed on the transverse steel strands or the longitudinal steel strands, and are used to collect the tension of the transverse steel strands or the longitudinal steel strands when falling rocks impact the flexible protective net; a plurality of displacement sensors are installed at the center of the flexible protective net and at symmetrical positions around the center of the flexible protective net, and are used to collect the displacement of the flexible protective net when falling rocks impact the flexible protective net.

[0029] The non-contact monitoring component comprises one of a high-speed camera, a laser speckle meter, an infrared imager and any combination thereof, and the non-contact monitoring component is aligned with the steel strand to be tested.

[0030] It should be noted that the above-mentioned electronic components are mature products on the market. This embodiment only needs to purchase them and connect them according to the instructions. No improvement is made to them, so their circuit connection structure and principle will not be described in detail here.

[0031] The design method of the flexible protective net multi-angle impact resistance test platform comprises the following steps: S1. Based on the constraint between the impact energy of the falling rock and the maximum absorbed energy of the flexible protection net, the number and length of the single steel strands constituting the flexible protection net, as well as the weight and height of the falling rock are designed; Step S1 specifically includes the following steps: S11. Consider the gravitational potential energy of the falling rock as the impact energy of the falling rock and calculate the impact energy of the falling rock: (1); In the formula, is the impact energy of the rockfall, in kJ; is the mass of the falling rock, in kg; is the acceleration due to gravity, and =9.8m / s 2 ; is the release height of the rockfall, in m; S12. Calculate the maximum absorbed energy of the flexible protective net: S121, galvanized anti-corrosion steel strands are used for both transverse and longitudinal steel strands, and the 0.2% yield strength of the steel strands is 310kN, the destructive force is 450kN, and the tensile strength is considered. Greater than 0.2% yield strength of steel strand and less than destructive force, the tensile strength of steel strand Set to 350kN; S122. Calculate the energy consumption of a single strand : (2); In the formula, represents the maximum elongation of a single strand, and , is the length of the steel strand; S123. Calculate the maximum absorbed energy of the flexible protective net : (3); In the formula, is the number of steel strands; S13. Assume that the impact energy of the falling rock is completely absorbed by the flexible protection net, and the maximum absorbed energy of the flexible protection net is equal to the gravitational potential energy of the falling rock when it is released: (4); S14. Design the number and length of single steel strands and the weight and height of falling rocks based on the constraints of formula (4).

[0032] S2. Design the layout spacing of the flexible protection net based on the shape of the falling rocks; Step S2 specifically includes the following steps: S21. Design the shape of the rockfall: simplify the 26-sided rockfall specimen into a regular hexahedron for calculation, and calculate the side length of the regular hexahedron : (5); In the formula, Indicates the speed of the falling rock when it contacts the flexible protective net; S22. Change the side length of the regular hexahedron It is regarded as the contact width between the falling rock and the flexible protective net, in meters. At the same time, the marginal effect of the falling rock impacting the flexible protective net is considered, and the width of the flexible protective net affected by the falling rock is calculated. : (6); In the formula, is a constant. In this embodiment, the constant Take 1m; S23, based on the calculation of the width of the flexible protective net affected by falling rocks , calculate the layout spacing between two adjacent steel strands in the same direction: (7); In the formula, for Layout spacing of steel strands, Direction is horizontal or vertical; in this embodiment, due to the calculated steel strand layout spacing It is usually a decimal, so the actual mesh spacing on site is Generally, it is smaller than the calculated steel strand layout spacing, so in this embodiment Take 0.2m.

[0033] S3. Design the height of the flexible protection net based on the maximum deformation height of the flexible protection net under the impact of falling rocks; In step S3, the rockfall impact drop distance is regarded as one of the right-angled sides of the right triangle and is set to , take the steel strand to be tested before impact as the other right-angled side of the right triangle, and assume that the elongation length of the steel strand to be tested after impact is equal to the maximum elongation of the steel strand, and take the elongated steel strand to be tested as the hypotenuse of the right triangle, then calculate the vertical deformation height of the flexible protective net according to the Pythagorean theorem: (8); In the formula, is the maximum descending distance of the flexible protective net under the impact of falling rocks, in meters. Deemed as the vertical deformation height of the flexible protective net; is the clear distance between two reaction walls, in m; is the elongation of a single steel strand; It is the length of the steel strand between the reaction wall and the ground anchor, in meters.

[0034] S4. Conduct test based on the designed rockfall and flexible protection net to test the stability of the test platform.

[0035] The test method of the flexible protective net multi-angle impact resistance test platform comprises the following steps: First, determine the test type and lay out the flexible protection net according to the test type: when conducting a vertical impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on the same horizontal line and then fix them to the ground via ground anchors; when conducting an inclined impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on different horizontal planes and then fix them to the ground via ground anchors; The falling rocks are then lifted to the rock release height using a lifting device and released. The rocks then fall freely until they impact the flexible protective net. During the impact, the status parameters of the flexible protective net are collected in real time with the help of a monitoring and analysis organization, and the performance test results are output.

[0036] In this embodiment, a 2D image of the amplitude change of the flexible protective net when impacted by falling rocks can be reconstructed based on the collected strain signals and displacement signals.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A flexible protective net multi-angle impact test platform, characterized by: It includes two opposing reaction walls, a flexible protective net arranged between the two reaction walls, a lifting device arranged above the flexible protective net, and a monitoring and analysis mechanism for monitoring the state parameters of the flexible protective net under the impact of falling rocks released by the lifting device; A plurality of positioning holes arranged in a rectangular array are provided on opposite sides of the two reaction walls, and the plurality of positioning holes on the two reaction walls are aligned one by one in the horizontal direction; The flexible protective net is composed of transverse steel strands and longitudinal steel strands arranged in a criss-cross pattern. The intersections of the transverse steel strands and the longitudinal steel strands are fixed by buckles. The two ends of the longitudinal steel strands pass through the positioning holes on the two reaction walls and are fixed to the ground by ground anchors.

2. The flexible protective net multi-angle impact resistance test platform according to claim 1 is characterized by: When the two ends of the longitudinal steel strand pass through two positioning holes at the same height, it is used to carry out a rockfall vertical impact test.

3. The flexible protective net multi-angle impact resistance test platform according to claim 1 is characterized by: When the two ends of the longitudinal steel strand pass through two positioning holes located at different heights, it is used to carry out the rockfall tilt impact test.

4. The flexible protective net multi-angle impact resistance test platform according to claim 1 is characterized by: The monitoring and analysis mechanism includes a contact monitoring component, a non-contact monitoring component, a data collector and a host computer. The contact monitoring component is connected to the host computer via the data collector, and the host computer is also connected to the non-contact monitoring component. The host computer is equipped with a DHDAS software platform, which is used to output the performance test results of the flexible protective net according to the state change parameters of the flexible protective net when impacted by falling rocks collected by the contact monitoring component and the non-contact monitoring component.

5. The flexible protective net multi-angle impact resistance test platform according to claim 4 is characterized in that: The contact monitoring components include: Multiple force sensors, which are installed at the connection point between the end of the transverse steel strand and the ground anchor or the connection point between the end of the longitudinal steel strand and the ground anchor, and are used to collect the force of each transverse steel strand and the force of each longitudinal steel strand when the falling rock impacts the flexible protection net; A plurality of strain rosettes are installed at a plurality of buckles arranged in a radial shape from the center of the flexible protection net, and are used to collect strains of the plurality of buckles radiating from the center to the outside when falling rocks impact the flexible protection net; A plurality of pull-wire sensors are installed at a plurality of buckles arranged in a radial shape at the center of the flexible protection net, and are used to collect the displacement of the plurality of buckles radiating from the center to the outside when falling rocks impact the flexible protection net; A plurality of three-dimensional acceleration sensors are installed at a plurality of buckles arranged in a radial shape from the center of the flexible protection net, and are used to collect the impact acceleration when the falling rock impacts the flexible protection net; A plurality of tension sensors are installed on the transverse steel strands or the longitudinal steel strands to collect the tension of the transverse steel strands or the longitudinal steel strands when falling rocks impact the flexible protective net; A plurality of displacement sensors are installed at the center of the flexible protective net and at symmetrical positions around the center of the flexible protective net, and are used to collect the displacement of the flexible protective net when falling rocks impact the flexible protective net.

6. The flexible protective net multi-angle impact resistance test platform according to claim 4 is characterized in that: The non-contact monitoring component comprises one of a high-speed camera, a laser speckle meter, an infrared imager and any combination thereof, and the non-contact monitoring component is aligned with the steel strand to be tested.

7. The design method of the flexible protective net multi-angle impact resistance test platform according to claim 5 or 6, characterized in that: The following steps are involved: S1. Based on the constraint between the impact energy of the falling rock and the maximum absorbed energy of the flexible protection net, the number and length of the single steel strands constituting the flexible protection net, as well as the weight and height of the falling rock are designed; S2. Design the layout spacing of the flexible protection net based on the shape of the falling rocks; S3. Design the height of the flexible protection net based on the maximum deformation height of the flexible protection net under the impact of falling rocks; S4. Conduct test based on the designed rockfall and flexible protection net to test the stability of the test platform.

8. The design method of the flexible protective net multi-angle impact resistance test platform according to claim 7 is characterized by: Step S1 specifically includes the following steps: S11. Consider the gravitational potential energy of the falling rock as the impact energy of the falling rock and calculate the impact energy of the falling rock: （1）； In the formula, is the impact energy of the rockfall, in kJ; is the mass of the falling rock, in kg; is the acceleration due to gravity, and =9.8m / s 2 ; is the release height of the rockfall, in m; S12. Calculate the maximum absorbed energy of the flexible protective net: S121, galvanized anti-corrosion steel strands are used for both transverse and longitudinal steel strands, and the 0.2% yield strength of the steel strands is 310kN, the destructive force is 450kN, and the tensile strength is considered. Greater than 0.2% yield strength of steel strand and less than destructive force, the tensile strength of steel strand Set to 350kN; S122. Calculate the energy consumption of a single strand : （2）； In the formula, represents the maximum elongation of a single strand, and , is the length of the steel strand; S123. Calculate the maximum absorbed energy of the flexible protective net : （3）； In the formula, is the number of steel strands; S13. Assume that the impact energy of the falling rock is completely absorbed by the flexible protection net, and the maximum absorbed energy of the flexible protection net is equal to the gravitational potential energy of the falling rock when it is released: （4）； S14. Design the number and length of single steel strands and the weight and height of falling rocks based on the constraints of formula (4).

9. The design method of the flexible protective net multi-angle impact resistance test platform according to claim 7 is characterized by: Step S2 specifically includes the following steps: S21. Design the shape of the rockfall: simplify the 26-sided rockfall specimen into a regular hexahedron for calculation, and calculate the side length of the regular hexahedron : （5）； In the formula, Indicates the speed of the falling rock when it contacts the flexible protective net; S22. Change the side length of the regular hexahedron It is regarded as the contact width between the falling rock and the flexible protective net, in meters. At the same time, the marginal effect of the falling rock impacting the flexible protective net is considered, and the width of the flexible protective net affected by the falling rock is calculated. : （6）； In the formula, is a constant; S23, based on the calculation of the width of the flexible protective net affected by falling rocks , calculate the layout spacing between two adjacent steel strands in the same direction: （7）； In the formula, for Layout spacing of steel strands, Direction is horizontal or vertical; In step S3, the rockfall impact drop distance is regarded as one of the right-angled sides of the right triangle and is set to , take the steel strand to be tested before impact as the other right-angled side of the right triangle, and assume that the elongation length of the steel strand to be tested after impact is equal to the maximum elongation of the steel strand, and take the elongated steel strand to be tested as the hypotenuse of the right triangle, then calculate the vertical deformation height of the flexible protective net according to the Pythagorean theorem: （8）； In the formula, is the maximum descending distance of the flexible protective net under the impact of falling rocks, in meters. Deemed as the vertical deformation height of the flexible protective net; is the clear distance between two reaction walls, in m; is the elongation of a single steel strand; It is the length of the steel strand between the reaction wall and the ground anchor, in meters.

10. The test method of the flexible protective net multi-angle impact resistance test platform according to claim 5 or 6, characterized in that: The following steps are involved: First, determine the test type and lay out the flexible protection net according to the test type: when conducting a vertical impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on the same horizontal line and then fix them to the ground via ground anchors; when conducting an inclined impact test, pass the two ends of the longitudinal steel strands of the flexible protection net through two positioning holes on different horizontal planes and then fix them to the ground via ground anchors; The falling rocks are then lifted to the rock release height using a lifting device and released. The rocks then fall freely until they impact the flexible protective net. During the impact, the status parameters of the flexible protective net are collected in real time with the help of a monitoring and analysis organization, and the performance test results are output.

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