Experimental device, design method and experimental method for vertical impact of steel strand by rockfall

Abstract

The invention discloses an experimental device, a design method and an experimental method for a steel strand vertically impacted by rockfall, and belongs to the field of rockfall vertical impact experiments. Comprising a reaction wall, two supporting frames symmetrically fixed to the same side of the reaction wall, a to-be-tested steel strand fixed between the two supporting frames through an anchorage device, lifting equipment arranged above the to-be-tested steel strand and a monitoring analysis mechanism, the power output end of the lifting equipment is connected with falling rocks, and the falling rocks are aligned to the to-be-tested steel strand; and the monitoring analysis mechanism is used for collecting the change of the to-be-tested steel strand in the vertical impact state of the rockfall and outputting a performance monitoring result. By adopting the experimental device, the design method and the experimental method for vertically impacting the steel strand by the rockfall, the rockfall impact limit parameters can be designed according to the parameters of the steel strand to be tested, so that the performance parameters of the steel strand close to the actual working state can be obtained, and the obtained result is more reliable.

Description

Technical Field

[0001] The invention relates to the technical field of rockfall vertical impact experiments, and in particular to an experimental device, a design method and an experimental method for rockfall vertical impact on a steel strand. Background Art

[0002] In order to effectively intercept and block the rocks rolling down the hillside and protect the vehicles, pedestrians, buildings and traffic routes below from being harmed by falling rocks, rockfall protection nets are set up in areas prone to rockfall disasters such as mountain roads, railways, slopes, tunnel entrances, etc. The rockfall protection nets are mainly composed of steel strands, anchors and supporting structures. Among them, the steel strands, as the main components of the protection nets, play the role of bearing, connecting and dispersing impact forces. Since the steel strands are easily impacted by different loads during work, it is easy to cause excessive force on the steel strands and cause safety hazards. Therefore, in order to ensure the performance of the steel strands, it is necessary to test the impact performance of the steel strands.

[0003] The existing steel strand impact performance test technology is as follows:

[0004] CN202211278612.8 discloses an anchor cable impact mechanical performance experimental device, which includes a support base, a support platform is provided above the support base, the support base and the support platform are connected by a plurality of first support plates, two fixed seats are provided on the top of the support platform, an anchor cable clamping mechanism is provided on the top of the fixed seat, a rectangular hole is opened on the top of the support base, one of the fixed seats is fixedly connected to the support base, and a first movable plate is fixedly connected to the bottom of the other fixed seat, and the first movable plate passes through the rectangular hole; the strength of the lateral impact force on the anchor cable can be adjusted, and the strength of the impact block hitting the anchor cable in the vertical direction can be adjusted, and it is convenient to change the position where the impact block hits the anchor cable.

[0005] CN202420308086.3 discloses an anchor cable impact mechanical performance experimental device, comprising a fixed base, the top of the fixed base is fixedly connected with a support leg, the top of the support leg is fixedly connected with a support plate; the support plate is provided with a fixed structure, the fixed structure comprises a support table, the bottom of the support table is fixedly connected to the top of the support plate, the top of the support table is provided with a through groove, and the top of the support table is provided with a slide groove. The utility model can fix anchor cables of different thicknesses by setting a fixed structure, and the anchor cables can be fixed inside the semi-arc plates on both sides by the cooperation between the sliding block, the semi-arc plate, the square clamping block, the square block and the clamping groove. At the same time, the length of the square clamping block and the clamping groove can be adjusted according to the thickness of the anchor cable, so that the anchor cable can be fixed more easily, achieving the effect of fixing anchor cables of different models, and greatly improving work efficiency.

[0006] It can be seen that the existing steel strand (anchor cable) performance experiments mostly remain in the laboratory stage and cannot truly simulate their working environment, resulting in large performance test errors. Summary of the invention

[0007] The purpose of the present invention is to provide an experimental device, a design method and an experimental method for vertical impact of falling rocks on steel strands, so as to solve the above-mentioned technical problems.

[0008] To achieve the above-mentioned purpose, the present invention provides an experimental device for vertical impact of falling rocks on steel strands, comprising a reaction wall, two support frames symmetrically fixed on the same side of the reaction wall, a steel strand to be tested fixed between the two support frames via an anchor, a lifting device arranged above the steel strand to be tested, and a monitoring and analysis mechanism, wherein the power output end of the lifting device is connected to the falling rocks, and the falling rocks are aligned with the steel strand to be tested;

[0009] The monitoring and analysis mechanism is used to collect the changes of the steel strand to be tested under the vertical impact state of falling rocks, and output the performance monitoring results.

[0010] Preferably, the monitoring and analysis mechanism includes a contact monitoring component and a non-contact monitoring component, wherein the contact monitoring component includes a tension sensor installed on the steel strand to be tested, a plurality of three-dimensional strain gauges, a displacement sensor, a piezoelectric acceleration sensor, and a piezoelectric force sensor installed between the support frame and the anchor;

[0011] The tension sensor, multiple three-dimensional strain gauges, displacement sensor, piezoelectric acceleration sensor and piezoelectric force sensor are all electrically connected to the input end of the data collector, and the output end of the data collector is electrically connected to the host computer;

[0012] Among them, the tension sensor is used to collect the tension of the steel strand to be tested;

[0013] Three-dimensional strain gauges are used to collect the stress state and deformation of the steel strand to be tested;

[0014] A displacement sensor, used to collect the displacement of the steel strand to be tested;

[0015] A piezoelectric acceleration sensor is used to collect the dynamic acceleration signal of the steel strand to be tested;

[0016] Piezoelectric force sensor is used to collect the impact force of the steel strand to be tested.

[0017] Preferably, the non-contact monitoring component includes one of a high-speed camera, a laser speckle meter, an infrared imager, and any combination thereof, and the non-contact monitoring component communicates with a host computer, and the host computer is equipped with a DHDAS software platform;

[0018] The non-contact monitoring assembly is aligned with the strand to be tested.

[0019] Preferably, the two support frames each include a transverse support rod with one end fixed to the reaction wall and an oblique pull rod fixedly connected to the other end of the transverse support rod, and the oblique pull rod is fixedly connected to the reaction wall;

[0020] Mounting holes are provided on opposite sides of the transverse support rods of the two support frames, and the two mounting holes are fixedly connected to the two ends of the steel strands respectively through anchors.

[0021] Preferably, the lifting equipment and the support frame are placed on both sides of the reaction wall.

[0022] The design method of the experimental device for vertical rockfall impact on steel strands comprises the following steps:

[0023] S1. Considering the 0.2% yield strength and destructive force of the steel strand to be tested, the tensile strength of the steel strand to be tested is set, and then combined with the ultimate tensile strength of the steel strand to be tested, the maximum impact energy of the steel strand to be tested is set:

[0024] Q=F ak ×ΔL (1);

[0025] Where, Q represents the maximum impact energy of the steel strand to be tested, in kJ; F ak Indicates the tensile strength of the steel strand to be tested, in kN; ΔL indicates the maximum elongation of the steel strand to be tested, in m;

[0026] S2. Relationship between the release height of the rockfall and the mass of the rockfall based on the maximum impact energy of the steel strand to be tested described in step S1:

[0027] Q = W = mgh (2);

[0028] Where W is the gravitational potential energy of the rockfall, in kJ; m is the mass of the rockfall, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the falling rock, in meters;

[0029] S3, based on the relationship between the release height of the falling rocks and the mass of the falling rocks described in step S2, and in combination with experimental requirements, setting the release height value of the falling rocks, and determining the mass of the falling rocks according to the release height value;

[0030] S4. The impact drop distance of the falling rock after it hits the steel strand to be tested is regarded as a triangle solving problem, and the impact drop distance is solved according to the Pythagorean theorem, and the height of the steel strand to be tested is designed according to the solved impact drop distance;

[0031] S5. Design the anchor force based on the release height and mass of the falling rocks.

[0032] Preferably, step S1 specifically includes the following steps:

[0033] S11. Take the NPR steel strand as the steel strand to be tested, and set the 0.2% yield strength of the NPR steel strand to 310kN, the destructive force to 450kN, and consider the tensile strength F ak The tensile strength F of the NPR steel strand is greater than 0.2% yield strength and less than the destructive force. ak Set to 350kN;

[0034] S12. Assuming the length of NPR steel strand is L, the maximum elongation expression is as follows:

[0035] ΔL = L × 10% = 0.1L (3);

[0036] S13, take L = 10m, then ΔL = 1m, set ΔL = 1m, F ak =350kN Substituting into formula (1), we obtain Q=350kJ.

[0037] Preferably, step S2 specifically includes the following steps:

[0038] S21. Assume that the impact energy of the falling rock is completely absorbed by the steel strand to be tested, and the gravitational potential energy of the falling rock is calculated as follows:

[0039] W = mgh (4);

[0040] Where W is the gravitational potential energy of the rockfall, in kJ; m is the mass of the rockfall, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the falling rock, in meters;

[0041] S22. The total energy absorbed by the tested steel strand will be regarded as the maximum impact energy, and the total energy absorbed by the tested steel strand is assumed to be equal to the gravitational potential energy of the falling rock, then:

[0042] Q=W=mgh (5).

[0043] Preferably, in step S3, the release height of the falling rock is set to h = 15 m, and h = 15 m and Q = 350 kJ are substituted into formula (2) to obtain m = 2.38 t;

[0044] In step S4, the rockfall impact drop distance is regarded as one of the right-angled sides of the right triangle, and is set as H. The steel strand to be tested before being impacted is taken as the other right-angled side of the right triangle. At the same time, it is assumed that the elongation length of the steel strand to be tested after being impacted is equal to the maximum elongation of the steel strand, and the elongated steel strand to be tested is taken as the hypotenuse of the right triangle, then:

[0045]

[0046] Substituting L = 10m, ΔL = 1m into formula (6), we can obtain H ≈ 2.3m, so the height of the steel strand to be tested is taken to be greater than 2.3m;

[0047] Step S5 specifically includes the following steps:

[0048] S51. Substitute h=15m into the following free fall formula:

[0049]

[0050] Calculated, v≈17.32m / s;

[0051] S52, setting the time for the tested steel strand to block the rockfall as t', and calculating the maximum vertical concentrated force transmitted by the rockfall to the tested steel strand according to the momentum theorem:

[0052] F / t'=m / v (8);

[0053] Where, F represents the maximum vertical concentrated force;

[0054] S53. Take t'=0.2s and substitute m=2.38t, v=17.32m / s into formula (8), and calculate F≈274.82kN, and regard the maximum vertical concentrated force F as the anchor force.

[0055] The experimental method of the experimental device for vertical impact of falling rocks on steel strands comprises the following steps:

[0056] The lifting equipment lifts the rockfall to the rockfall release height and then releases it. The rockfall falls freely until it impacts the steel strand to be tested. During the impact process, the tension, stress, displacement, acceleration, and impact force of the steel strand to be tested are collected in real time with the help of a monitoring and analysis mechanism. A stress-strain curve, an axial tension time-history curve, an impact force time-history curve, and an impact force-deformation curve are drawn based on the collected tension, stress, displacement, acceleration, and impact force. The elongation is calculated, and the stress when the steel strand to be tested breaks is taken as the breaking strength, thereby obtaining a characteristic curve of the energy consumption of the anchor cable.

[0057] The stress-strain curve drawing method is as follows: pair the collected stress and strain data: strain ε = L + ΔL / L, and draw the stress-strain curve with strain as the abscissa and stress as the ordinate;

[0058] The method for drawing the axial tension time history curve is as follows: using time as the abscissa and the tension changing with time as the ordinate to draw the axial tension time history curve;

[0059] The method for drawing the impact force time history curve is as follows: using time as the abscissa and the impact force changing with time as the ordinate to draw the impact force time history curve;

[0060] The method for drawing the impact force-deformation curve is as follows: using the impact force as the ordinate and the displacement as the abscissa to draw the impact force-deformation curve;

[0061] The calculation formula of elongation εf is as follows:

[0062] εf=(Lf-L) / L (9);

[0063] Where, Lf represents the total elongation of the tested steel strand when it breaks;

[0064] The calculation formula of anchor cable energy consumption E is as follows:

[0065] E = 1 / 2 × F × d (10);

[0066] Where d represents the vertical displacement of the tested steel strand under impact.

[0067] Therefore, the present invention adopts the above-mentioned experimental device, design method and experimental method for vertical impact of falling rocks on steel strands, which has the following beneficial effects:

[0068] The rockfall impact limit parameters can be designed according to the parameters of the steel strand to be tested, so that the performance parameters of the steel strand close to the actual working state can be obtained, and the results obtained are more reliable.

[0069] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a schematic diagram of the structure of the experimental device for vertical impact of falling rocks on steel strands of the present invention;

[0071] Figure 2 Graph showing the stress-strain curve of this embodiment.

[0072] Reference numerals

[0073] 1. Lifting equipment; 2. Falling rocks; 3. Reaction wall; 4. Support frame; 41. Horizontal support rod; 42. Diagonal pull rod. DETAILED DESCRIPTION

[0074] 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.

[0075] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0076] like Figure 1 As shown, an experimental device for vertical rockfall impact on steel strands includes a reaction wall 3, two support frames 4 symmetrically fixed on the same side of the reaction wall 3, a steel strand to be tested fixed between the two support frames 4 via anchors, a lifting device 1 arranged above the steel strand to be tested, and a monitoring and analysis mechanism, wherein the power output end of the lifting device 1 is connected to a rockfall 2, and the rockfall 2 is aligned with the steel strand to be tested; the monitoring and analysis mechanism is used for collecting changes in the steel strand to be tested under the vertical impact state of the rockfall 2, and outputting performance monitoring results.

[0077] The monitoring and analysis mechanism includes a contact monitoring component and a non-contact monitoring component, wherein the contact monitoring component includes a tension sensor installed on the steel strand to be tested, multiple three-dimensional strain gauges, a displacement sensor, a piezoelectric acceleration sensor, and a piezoelectric force sensor installed between the support frame 4 and the anchor; the tension sensor, multiple three-dimensional strain gauges, the displacement sensor, the piezoelectric acceleration sensor, and the piezoelectric force sensor are all electrically connected to the input end of the data collector, and the output end of the data collector is electrically connected to the host computer; wherein the tension sensor is used to collect the tension of the steel strand to be tested; the three-dimensional strain gauge is used to collect the stress state and deformation of the steel strand to be tested; the displacement sensor is used to collect the displacement of the steel strand to be tested; the piezoelectric acceleration sensor is used to collect the dynamic acceleration signal of the steel strand to be tested; the piezoelectric force sensor is used to collect the impact force of the steel strand to be tested.

[0078] The non-contact monitoring component includes one of a high-speed camera, a laser speckle meter, an infrared imager, and any combination thereof. The non-contact monitoring component communicates with a host computer, and the host computer is equipped with a DHDAS software platform. The non-contact monitoring component is aligned with the steel strand to be tested, so that waveform detection can be performed with the help of the DHDAS software platform.

[0079] It should be noted that the above-mentioned electronic components are mature products on the market. In this embodiment, they only need to be purchased and connected according to the instructions, so their circuit connection structure and principle will not be described in detail here.

[0080] Each of the two support frames 4 includes a transverse support rod 41 with one end fixed on the reaction wall 3 and an oblique pull rod 42 fixedly connected to the other end of the transverse support rod 41, and the oblique pull rod 42 is fixedly connected to the reaction wall 3; mounting holes are opened on the opposite sides of the transverse support rod 41 of the two support frames 4, and the two mounting holes are fixedly connected to the two ends of the steel strands through anchors, so that the support frames 4 are fixed on the reaction wall 3. Compared with the traditional ground fixing method, the structure of the support frames 4 is simplified.

[0081] The lifting device 1 and the support frame 4 are placed on both sides of the reaction wall 3, and the spatial layout is more reasonable.

[0082] The design method of the experimental device for vertical impact of falling rocks on steel strands comprises the following steps:

[0083] S1. Considering the 0.2% yield strength and destructive force of the steel strand to be tested, the tensile strength of the steel strand to be tested is set, and then combined with the ultimate tensile strength of the steel strand to be tested, the maximum impact energy of the steel strand to be tested is set:

[0084] Q=F ak ×ΔL (1);

[0085] Where, Q represents the maximum impact energy of the steel strand to be tested, in kJ; F ak Indicates the tensile strength of the steel strand to be tested, in kN; ΔL indicates the maximum elongation of the steel strand to be tested, in m;

[0086] S2, based on the maximum impact energy of the steel strand to be tested described in step S1, the relationship between the release height of the rockfall 2 and the mass of the rockfall 2 is:

[0087] Q = W = mgh (2);

[0088] Where W is the gravitational potential energy of the falling rock 2, in kJ; m is the mass of the falling rock 2, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the rockfall 2, in m;

[0089] S3, based on the relationship between the release height of the falling rock 2 and the mass of the falling rock 2 described in step S2, and in combination with experimental requirements, setting the release height value of the falling rock 2, and determining the mass of the falling rock 2 according to the release height value;

[0090] S4, treating the distance that the rockfall 2 drops after impacting the steel strand to be tested as a triangle problem, solving the impact drop distance according to the Pythagorean theorem, and designing the height of the steel strand to be tested according to the solved impact drop distance;

[0091] S5. Design the anchor force based on the release height of the rockfall 2 and the mass of the rockfall 2.

[0092] Step S1 specifically includes the following steps:

[0093] S11. Take the NPR steel strand as the steel strand to be tested, and set the 0.2% yield strength of the NPR steel strand to 310kN, the destructive force to 450kN, and consider the tensile strength F ak The tensile strength F of the NPR steel strand is greater than 0.2% yield strength and less than the destructive force. ak Set to 350kN;

[0094] S12. Assuming the length of NPR steel strand is L, the maximum elongation expression is as follows:

[0095] ΔL = L × 10% = 0.1L (3);

[0096] S13, take L = 10m, then ΔL = 1m, set ΔL = 1m, F ak =350kN Substituting into formula (1), we obtain Q=350kJ.

[0097] Step S2 specifically includes the following steps:

[0098] S21. Assume that the impact energy of the rockfall 2 is completely absorbed by the steel strand to be tested, and the calculation formula of the gravitational potential energy of the rockfall 2 is as follows:

[0099] W = mgh (4);

[0100] Where W is the gravitational potential energy of the falling rock 2, in kJ; m is the mass of the falling rock 2, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the rockfall 2, in m;

[0101] S22. The total energy absorbed by the tested steel strand will be regarded as the maximum impact energy, and the total energy absorbed by the tested steel strand is assumed to be equal to the gravitational potential energy of the falling rock 2, then:

[0102] Q=W=mgh (5).

[0103] In step S3, the release height of the rockfall 2 is set to h = 15 m, and h = 15 m and Q = 350 kJ are substituted into formula (2) to obtain m = 2.38 t;

[0104] In step S4, the impact drop distance of the rockfall 2 is regarded as one of the right-angled sides of the right triangle, and is set as H. The steel strand to be tested before being impacted is taken as the other right-angled side of the right triangle. At the same time, it is assumed that the elongation length of the steel strand to be tested after being impacted is equal to the maximum elongation of the steel strand, and the elongated steel strand to be tested is taken as the hypotenuse of the right triangle, then:

[0105]

[0106] Substituting L = 10m, ΔL = 1m into formula (6), we can obtain H ≈ 2.3m, so the height of the steel strand to be tested is taken to be greater than 2.3m;

[0107] Step S5 specifically includes the following steps:

[0108] S51. Substitute h=15m into the following free fall formula:

[0109]

[0110] It is calculated that v≈17.32m / s;

[0111] S52, set the time for the tested steel strand to block the rockfall 2 as t'. It should be noted that this value is an empirical estimate. The maximum vertical concentrated force transmitted by the rockfall 2 to the tested steel strand is calculated according to the momentum theorem:

[0112] F / t'=m / v (8);

[0113] Where, F represents the maximum vertical concentrated force;

[0114] S53, take t'=0.2s and substitute m=2.38t, v=17.32m / s into formula (8),

[0115] The calculated value is F≈274.82kN, and the maximum vertical concentrated force F is regarded as the anchor force.

[0116] The experimental method of the experimental device for vertically impacting a steel strand with falling rocks 2 comprises the following steps:

[0117] The lifting device 1 lifts the rockfall 2 to the release height of the rockfall 2 and then releases it. The rockfall 2 falls freely until it impacts the steel strand to be tested. During the impact process, the tension, stress, displacement, acceleration, and impact force of the steel strand to be tested are collected in real time with the help of a monitoring and analysis mechanism. A stress-strain curve, an axial tension time-history curve, an impact force time-history curve, and an impact force-deformation curve are drawn based on the collected tension, stress, displacement, acceleration, and impact force. The elongation is calculated, and the stress when the steel strand to be tested breaks is taken as the breaking strength, thereby obtaining a characteristic curve of the energy consumption of the anchor cable.

[0118] The stress-strain curve is drawn by pairing the collected stress and strain data: strain ε = L + ΔL / L, and drawing the curve with strain as the horizontal axis and stress as the vertical axis. Figure 2 The stress-strain curve shown;

[0119] The method for drawing the axial tension time history curve is as follows: using time as the abscissa and the tension changing with time as the ordinate to draw the axial tension time history curve;

[0120] The method for drawing the impact force time history curve is as follows: using time as the abscissa and the impact force changing with time as the ordinate to draw the impact force time history curve;

[0121] The method for drawing the impact force-deformation curve is as follows: using the impact force as the ordinate and the displacement as the abscissa to draw the impact force-deformation curve;

[0122] The calculation formula of elongation εf is as follows:

[0123] εf=(Lf-L) / L (9);

[0124] Where, Lf represents the total elongation of the tested steel strand when it breaks;

[0125] The calculation formula of anchor cable energy consumption E is as follows:

[0126] E = 1 / 2 × F × d (10);

[0127] Where d represents the vertical displacement of the tested steel strand under impact.

[0128] 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. An experimental device for vertical impact of falling rocks on steel strands, characterized in that: It includes a reaction wall, two support frames symmetrically fixed on the same side of the reaction wall, a steel strand to be tested fixed between the two support frames via an anchor, a lifting device arranged above the steel strand to be tested, and a monitoring and analysis mechanism, wherein a rockfall is connected to a power output end of the lifting device, and the rockfall is aligned with the steel strand to be tested; The monitoring and analysis mechanism is used to collect the changes of the steel strand to be tested under the vertical impact state of falling rocks, and output the performance monitoring results.

2. The experimental device for vertical rockfall impact on steel strands according to claim 1, characterized in that: The monitoring and analysis mechanism includes a contact monitoring component and a non-contact monitoring component, wherein the contact monitoring component includes a tension sensor installed on the steel strand to be tested, a plurality of three-dimensional strain gauges, a displacement sensor, a piezoelectric acceleration sensor, and a piezoelectric force sensor installed between the support frame and the anchor; The tension sensor, multiple three-dimensional strain gauges, displacement sensor, piezoelectric acceleration sensor and piezoelectric force sensor are all electrically connected to the input end of the data collector, and the output end of the data collector is electrically connected to the host computer; Among them, the tension sensor is used to collect the tension of the steel strand to be tested; Three-dimensional strain gauges are used to collect the stress state and deformation of the steel strand to be tested; A displacement sensor, used to collect the displacement of the steel strand to be tested; A piezoelectric acceleration sensor is used to collect the dynamic acceleration signal of the steel strand to be tested; Piezoelectric force sensor is used to collect the impact force of the steel strand to be tested.

3. The experimental device for vertical impact of falling rocks on steel strands according to claim 2 is characterized in that: The non-contact monitoring component includes one of a high-speed camera, a laser speckle meter, an infrared imager, or any combination thereof. The non-contact monitoring component communicates with a host computer, and the host computer is equipped with a DHDAS software platform; The non-contact monitoring assembly is aligned with the strand to be tested.

4. The experimental device for vertical rockfall impact on steel strands according to claim 1, characterized in that: The two support frames each include a transverse support rod with one end fixed to the reaction wall and an oblique pull rod fixedly connected to the other end of the transverse support rod, and the oblique pull rod is fixedly connected to the reaction wall; Mounting holes are provided on opposite sides of the transverse support rods of the two support frames, and the two mounting holes are fixedly connected to the two ends of the steel strands respectively through anchors.

5. The experimental device for vertical rockfall impact on steel strands according to claim 1, characterized in that: The lifting equipment and the supporting frame are placed on both sides of the reaction wall.

6. The design method of the experimental device for vertical rockfall impact on steel strands according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Considering the 0.2% yield strength and destructive force of the steel strand to be tested, the tensile strength of the steel strand to be tested is set, and then combined with the ultimate tensile strength of the steel strand to be tested, the maximum impact energy of the steel strand to be tested is set: Q=F ak ×ΔL (1); Where, Q represents the maximum impact energy of the steel strand to be tested, in kJ; F ak Indicates the tensile strength of the steel strand to be tested, in kN; ΔL indicates the maximum elongation of the steel strand to be tested, in m; S2. Relationship between the release height of the rockfall and the mass of the rockfall based on the maximum impact energy of the steel strand to be tested described in step S1: Q = W = mgh (2); Where W is the gravitational potential energy of the rockfall, in kJ; m is the mass of the rockfall, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the falling rock, in meters; S3, based on the relationship between the release height of the falling rocks and the mass of the falling rocks described in step S2, and in combination with experimental requirements, setting the release height value of the falling rocks, and determining the mass of the falling rocks according to the release height value; S4. The impact drop distance of the falling rock after it hits the steel strand to be tested is regarded as a triangle solving problem, and the impact drop distance is solved according to the Pythagorean theorem, and the height of the steel strand to be tested is designed according to the solved impact drop distance; S5. Design the anchor force based on the release height and mass of the falling rocks.

7. The design method of the experimental device for vertical rockfall impact on steel strands according to claim 6 is characterized by: Step S1 specifically includes the following steps: S11. Take the NPR steel strand as the steel strand to be tested, and set the 0.2% yield strength of the NPR steel strand to 310kN, the destructive force to 450kN, and consider the tensile strength F ak The tensile strength F of the NPR steel strand is greater than 0.2% yield strength and less than the destructive force. ak Set to 350kN; S12. Assuming the length of NPR steel strand is L, the maximum elongation expression is as follows: ΔL = L × 10% = 0.1L (3); S13, take L = 10m, then ΔL = 1m, set ΔL = 1m, F ak =350kN Substituting into formula (1), we obtain Q=350kJ.

8. The design method of the experimental device for vertical rockfall impact on steel strands according to claim 7 is characterized by: Step S2 specifically includes the following steps: S21. Assume that the impact energy of the falling rock is completely absorbed by the steel strand to be tested, and the gravitational potential energy of the falling rock is calculated as follows: W = mgh (4); Where W is the gravitational potential energy of the rockfall, in kJ; m is the mass of the rockfall, in kg; g is the acceleration due to gravity, and g = 9.8 m / s 2 ; h is the release height of the falling rock, in meters; S22. The total energy absorbed by the tested steel strand will be regarded as the maximum impact energy, and the total energy absorbed by the tested steel strand is assumed to be equal to the gravitational potential energy of the falling rock, then: Q=W=mgh (5).

9. The design method of the experimental device for vertical rockfall impact on steel strands according to claim 8 is characterized by: In step S3, the release height of the rockfall is set to h = 15 m, and h = 15 m and Q = 350 kJ are substituted into formula (2) to obtain m = 2.38 t; In step S4, the rockfall impact drop distance is regarded as one of the right-angled sides of the right triangle, and is set as H. The steel strand to be tested before being impacted is taken as the other right-angled side of the right triangle. At the same time, it is assumed that the elongation length of the steel strand to be tested after being impacted is equal to the maximum elongation of the steel strand, and the elongated steel strand to be tested is taken as the hypotenuse of the right triangle, then: Substituting L = 10m, ΔL = 1m into formula (6), we can obtain H ≈ 2.3m, so the height of the steel strand to be tested is taken to be greater than 2.3m; Step S5 specifically includes the following steps: S51. Substitute h=15m into the following free fall formula: Calculated, v≈17.32m / s; S52, setting the time for the tested steel strand to block the rockfall as t', and calculating the maximum vertical concentrated force transmitted by the rockfall to the tested steel strand according to the momentum theorem: F / t'=m / v (8); Where, F represents the maximum vertical concentrated force; S53. Take t'=0.2s and substitute m=2.38t, v=17.32m / s into formula (8), and calculate F≈274.82kN, and regard the maximum vertical concentrated force F as the anchor force.

10. The experimental method of the experimental device for vertical rockfall impact on steel strands according to any one of claims 1 to 5, characterized in that: The following steps are involved: The lifting equipment lifts the rockfall to the rockfall release height and then releases it. The rockfall falls freely until it impacts the steel strand to be tested. During the impact process, the tension, stress, displacement, acceleration, and impact force of the steel strand to be tested are collected in real time with the help of a monitoring and analysis mechanism. A stress-strain curve, an axial tension time-history curve, an impact force time-history curve, and an impact force-deformation curve are drawn based on the collected tension, stress, displacement, acceleration, and impact force. The elongation is calculated, and the stress when the steel strand to be tested breaks is taken as the breaking strength, thereby obtaining a characteristic curve of the energy consumption of the anchor cable. The stress-strain curve drawing method is: pair the collected stress and strain data: strain ε = L + ΔL / L, and draw the stress-strain curve with strain as the horizontal coordinate and stress as the vertical coordinate; The method for drawing the axial tension time history curve is as follows: using time as the abscissa and the tension changing with time as the ordinate to draw the axial tension time history curve; The method for drawing the impact force time history curve is as follows: using time as the abscissa and the impact force changing with time as the ordinate to draw the impact force time history curve; The method for drawing the impact force-deformation curve is as follows: using the impact force as the ordinate and the displacement as the abscissa to draw the impact force-deformation curve; The calculation formula of elongation εf is as follows: εf=(Lf-L) / L (9); Where, Lf represents the total elongation of the tested steel strand when it breaks; The calculation formula of anchor cable energy consumption E is as follows: E = 1 / 2 × F × d (10); Where d represents the vertical displacement of the tested steel strand under impact.

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