Test calibration method for quantifying the impact force of rockfall on a shed structure

Abstract

This invention relates to a test calibration method for quantifying the impact force of falling rocks on tunnel structures. The method includes: constructing a tunnel structure model and installing resistance strain gauges, pressure sensors, and accelerometers; releasing a drop hammer and acquiring collected data; using the collected data to calculate the instantaneous impact force upon contact between the drop hammer and the tunnel structure model, the response impact force of the tunnel structure model, and the feedback impact force of the tunnel structure model; calibrating the response impact force by comparing and judging the numerical values ​​of the instantaneous impact force, response impact force, and feedback impact force, obtaining the final impact force, and determining safety. This invention simulates similar disasters in the laboratory, determines the actual impact force borne by the structure after inversion of the instrument-collected data, and uses this data to determine the structure's safety after structural calculation. The calculation process is clear and accurate, realizing the quantification of the impact force of falling rocks on tunnel structures, which is more reliable than previous judgments based solely on experience, ensuring the service safety of tunnel structures after withstanding falling rock impacts.

Description

Technical Field

[0001] This invention relates to the field of road engineering testing technology, specifically to a test calibration method for quantifying the impact force of falling rocks on tunnel structures. Background Technology

[0002] The complex and rugged terrain of mountainous areas leads to frequent geological disasters such as rockfalls, mudslides, landslides, and earthquakes. Rockfalls are one of the most common geological hazards encountered and requiring prevention and control when constructing railways, highways, and other transportation routes in mountainous areas. Currently, the common engineering measure for preventing rockfalls along transportation routes is to use covered tunnel structures.

[0003] However, there is no reliable algorithm for the dynamic response of structures such as sheds to rockfall impacts. Once a structure is subjected to a huge rockfall impact and suffers damage of varying degrees, whether the structure should continue to serve or be reinforced before service can only be judged based on experience, lacking quantitative scientific analysis.

[0004] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a test calibration method for quantifying the impact force of falling rocks on tunnel structures, in order to solve the problem that currently, we can only rely on experience to determine whether a tunnel structure can continue to serve after being subjected to falling rock impacts.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A test calibration method for quantifying the impact force of falling rocks on tunnel structures, the method comprising:

[0008] Construct a model of the shed / cave structure;

[0009] Resistance strain gauges were pre-installed inside the shed structure model;

[0010] Pressure sensors were pre-installed at the bottom of the tunnel structure model;

[0011] A drop hammer is suspended above the tunnel structure model, and an acceleration sensor is installed on the drop hammer;

[0012] Release the drop hammer and acquire data from resistance strain gauges, pressure sensors, and acceleration sensors when the drop hammer impacts the tunnel structure model.

[0013] Using data collected by an accelerometer, the instantaneous impact force at which the drop hammer contacts the tunnel structure model is calculated;

[0014] The response impact force of the tunnel structure model was calculated using data collected by a resistance strain gauge.

[0015] The feedback impact force of the tunnel structure model is calculated using data collected by pressure sensors.

[0016] By comparing and judging the values ​​of instantaneous impact force, response impact force, and feedback impact force, the response impact force is calibrated to obtain the final impact force.

[0017] Furthermore, a structural model of the shed / cave is constructed, including:

[0018] The shed structure model is a reinforced concrete structure with a mesh of reinforcing steel bars inside to resist bending, and the bottom on both sides is supported by shed supports.

[0019] Furthermore, resistance strain gauges are pre-installed within the shed structure model, including:

[0020] When tying the reinforcing bars of the shed, resistance strain gauges are tied to the reinforcing bars at the typical locations that bear structural impact, and then the concrete of the shed structure is poured.

[0021] Typical locations include the mid-span, quarter-span, and fulcrum.

[0022] Furthermore, pressure sensors are pre-installed at the bottom of the shed structure model, including:

[0023] A pressure sensor sleeve is reserved at the bottom of the support pier of the tunnel, and a pressure sensor is installed at the pressure sensor sleeve.

[0024] Furthermore, a drop hammer is suspended above the tunnel structure model, and an acceleration sensor is installed on the drop hammer, including:

[0025] The surface of the drop hammer is a steel plate shell, with concrete poured inside.

[0026] Pre-embed steel strand suspension ropes before concrete pouring;

[0027] The steel strand suspension rope is suspended from the tower hook;

[0028] A groove is reserved at the top of the drop hammer, and an acceleration sensor is embedded in the groove.

[0029] Furthermore, using data collected by the accelerometer, the instantaneous impact force at which the drop hammer contacts the tunnel structure model is calculated, including:

[0030] The accelerometer is connected to an external accelerometer data acquisition system;

[0031] Acquire data from the acceleration data acquisition system and calculate the instantaneous impact force F when the drop hammer contacts the tunnel structure model. a-max :

[0032]

[0033] F a-max =mz ×a max ;

[0034] in:

[0035] v z The instantaneous velocity of the drop hammer impacting the tunnel structure model;

[0036] T represents the time from the release of the drop hammer to the impact on the tunnel structure model;

[0037] a i The acceleration time history of the drop hammer from release to the tunnel structure model;

[0038] m z The mass of the falling hammer;

[0039] a max The maximum acceleration time history is the process of the falling hammer impacting the tunnel structure model.

[0040] Furthermore, using the data collected by the resistance strain gauge, the response impact force of the tunnel structure model is calculated, including:

[0041] The resistance strain gauge is connected to an external strain data acquisition system.

[0042] Acquire data from the strain data acquisition system and calculate the response impact force F of the tunnel structure model. b-max :

[0043] σ z =ε max ×E;

[0044] F b-max =σ z ×JW z ;

[0045] in:

[0046] σ z This represents the maximum stress on the reinforcing steel bars in the shed.

[0047] ε max The maximum stress was measured for the reinforcing steel bars in the shed opening;

[0048] E is the elastic modulus of the steel reinforcement;

[0049] JW z It is the product of the moment conversion factor and the section bending stiffness.

[0050] Furthermore, using data collected by pressure sensors, the feedback impact force of the tunnel structure model is calculated, including:

[0051] The pressure sensor is connected to an external pressure sensor data acquisition system.

[0052] Acquire data from the pressure sensor data acquisition system and calculate the feedback impact force F of the tunnel structure model. c-max :

[0053] F c-max =F zd -(m z +m p g;

[0054] in:

[0055] F zd This represents the maximum vertical reaction force at the bottom of the support pier during the impact of the falling hammer.

[0056] m p The quality of the shed structure model;

[0057] g is the acceleration due to gravity.

[0058] Furthermore, by comparing and judging the values ​​of instantaneous impact force, response impact force, and feedback impact force, the response impact force is calibrated to obtain the final impact force, including:

[0059] Numerical comparisons were made of instantaneous impact force, response impact force, and feedback impact force to meet the requirements.

[0060] F a-max >F b-max >F c-max ;

[0061] Error judgment is performed on instantaneous impact force, response impact force, and feedback impact force to meet the requirements.

[0062] and

[0063] Repeated numerical comparisons and error assessments were performed, and the response impact force F was determined by extracting data from multiple sets of data. b-max Calibration, forming the final impact force F max .

[0064] Furthermore, the method also includes:

[0065] After constructing the shed structure model, a buffer layer is poured on top of the shed structure model, and a buffer layer is laid inside the buffer layer.

[0066] When the drop hammer is released, it impacts the buffer layer.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] This invention provides a test calibration method for quantifying the impact force of falling rocks on tunnel structures. It simulates similar disasters in the laboratory, and determines the actual impact force on the structure by inverting the data collected by the instrument. The impact force load is then used to check the structure and determine the safety of the structure. The calculation process is clear and accurate, realizing the quantification of the impact force of falling rocks on tunnel structures. This method is more reliable than the previous judgment based solely on experience and ensures the service safety of tunnel structures after being subjected to the impact force of falling rocks. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0070] Figure 1 A schematic diagram illustrating a disaster caused by falling rocks impacting a tunnel structure.

[0071] Figure 2 This is the overall design drawing for the rockfall impact test tunnel (concrete materials are not shown).

[0072] Figure 3 This is the overall design drawing for the rockfall impact test tunnel (showing the concrete material).

[0073] Figure 4 This is a graph showing the results extracted from the accelerometer in the embodiment.

[0074] Figure 5 This is a flowchart of the method of the present invention.

[0075] The diagram is labeled as follows:

[0076] 601-Drop hammer, 602-Tower hook, 603-Acceleration sensor, 604-Acceleration data acquisition system, 605-Buffer layer, 606-Buffer layer enclosure, 607-Shelter structure model, 608-Shelter reinforcement, 609-Resistance strain gauge, 610-Strain data acquisition system, 611-Shelter support, 612-Pressure sensor, 613-Pressure sensor data acquisition system, 614-Steel strand suspension rope. Detailed Implementation

[0077] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0078] It should be noted that similar reference numerals and letters indicate similar items; therefore, once an item is defined in one embodiment, it does not need to be further defined and explained in subsequent embodiments. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0079] It should also be noted that although the order of steps is mentioned in the method description, in some cases, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0080] like Figure 1 Rockfall impact is a complex process of kinetic energy conversion. Determining the magnitude of the impact force involves two methods: first, measuring the initial energy before the impact; and second, converting the object's velocity into the rockfall impact force using the impulse theorem. Assessing whether a structure can function normally after withstanding an impact force requires calculating the structural safety by combining the impact force value with material properties. The impact of rockfalls occurring on-site is difficult to quantify. Therefore, it is necessary to collect parameters through rockfall impact force tests and then inversely calculate three types of rockfall impact forces. The final rockfall impact force is determined after calibration through tests with different rockfall impact force values.

[0081] like Figure 2 , Figure 3 and Figure 5 This invention provides a test calibration method for quantifying the impact force of falling rocks on a tunnel structure, the method comprising:

[0082] S1: Construct the shed / cave structure model 607, including:

[0083] The shed structure model 607 is a reinforced concrete structure with a mesh of shed steel bars 608 inside to resist bending, and the bottom on both sides is supported by shed support piers 611.

[0084] S2: Resistance strain gauges 609 are pre-installed within the shed structure model 607, including:

[0085] When tying the reinforcing bars 608 for the shed opening, resistance strain gauges 609 are tied at the reinforcing bars in typical locations that bear structural impact, and then the concrete for the shed opening structure is poured.

[0086] Typical locations include the mid-span, quarter-span, and fulcrum.

[0087] S3: Pressure sensors 612 are pre-installed at the bottom of the tunnel structure model 607, including:

[0088] A pressure sensor sleeve is reserved at the bottom of the support 611 of the tunnel, and a pressure sensor 612 is installed at the pressure sensor sleeve.

[0089] S4: A drop hammer 601 is suspended above the tunnel structure model 607, and an acceleration sensor 603 is installed on the drop hammer 601, including:

[0090] S401: The surface of the drop hammer 601 is a steel plate shell, and the inside is filled with concrete;

[0091] S402: 614 steel strand suspension rope pre-embedded before concrete pouring;

[0092] S403: Steel strand suspension rope 614 is suspended from tower hook 602;

[0093] S404: A groove is reserved on the top of the drop hammer 601, and the accelerometer 603 is embedded in the groove.

[0094] Install tower hook 602 at the test site and determine the position where the drop hammer 601 is released into free fall to simulate the impact according to the design energy. The plane position of the drop hammer should be directly above the top of the shed structure model 607 and the drop hammer should be installed there.

[0095] The above steps complete the construction of the experimental system. Before that, the following design verifications are required:

[0096] ① Determination of the initial energy of the falling rock:

[0097] To determine the characteristics of the affected structure, a site survey of the disaster site is required. This involves collecting the mass m of the fallen rock and the height h of the rock relative to the structure when it is at rest. The impact energy of the rock acting on the structure can be calculated using the gravitational potential energy formula, i.e., E0 = mgh (where E0 is the initial energy, m is the mass, g is the gravitational acceleration, and h is the height of the structure).

[0098] ② Select the drop hammer 601 to simulate falling rocks and the tower hook 602 to simulate the height of falling rocks in the test. By selecting drop hammers of different weights, the height of the hook can be reduced to ensure the safety of the test.

[0099] S5: Release the drop hammer 601. When the drop hammer 601 impacts the tunnel structure model 607, acquire the data collected by the resistance strain gauge 609, pressure sensor 612 and acceleration sensor 603.

[0100] The resistance strain gauge 609 can be a model 120-5AA strain gauge device, used to acquire the maximum stress of the reinforcing steel 608 in the tunnel. The pressure sensor 612 can be a GH-4 spoke-type sensor device, used to acquire the maximum vertical reaction force at the bottom of the tunnel support 611. The acceleration sensor 603 can be a DH5916 miniature dynamic data acquisition device, used to acquire the acceleration time history of the drop hammer 601 from release to the tunnel structural model 607. Of course, other commercially available devices capable of the above acquisition functions can also be used to implement this method.

[0101] S6: Using the data collected by the accelerometer 603, calculate the instantaneous impact force when the drop hammer 601 contacts the tunnel structure model 607, including:

[0102] Accelerometer 603 is connected to an externally installed acceleration data acquisition system 604. It acquires data from the acceleration data acquisition system 604 and calculates the instantaneous impact force F when the drop hammer 601 contacts the tunnel structure model 607. a-max :

[0103]

[0104] F a-max =m z ×a max ;

[0105] in:

[0106] v z The instantaneous velocity of the falling hammer 601 impacting the tunnel structure model 607;

[0107] T is the time from the release of the drop hammer 601 to the impact on the tunnel structure model 607;

[0108] a i The acceleration time history of the drop hammer 601 from release to the tunnel structure model 607;

[0109] m z The mass of the falling hammer 601;

[0110] a max The time history of the maximum acceleration during the impact of the falling hammer 601 on the tunnel structure model 607.

[0111] S7: Using the data collected by the resistance strain gauge 609, calculate the response impact force of the tunnel structure model 607, including:

[0112] The resistance strain gauge 609 is connected to an external strain data acquisition system 610. The system acquires data from the strain data acquisition system 610 and calculates the response impact force F of the tunnel structure model 607. b-max :

[0113] σz =ε max ×E;

[0114] F b-max =σ z ×JW z ;

[0115] in:

[0116] σ z The maximum stress of the 608 steel reinforcement in the shed opening;

[0117] ε max The maximum stress was measured for the 608 steel reinforcement in the shed opening.

[0118] E is the elastic modulus of the steel reinforcement;

[0119] JW z This is the product of the moment conversion factor and the section bending stiffness. This value is calculated using finite element analysis software; the specific calculation process is existing technology, and this method does not offer any further improvements.

[0120] S8: Using the data collected by pressure sensor 612, calculate the feedback impact force of the tunnel structure model 607, including:

[0121] Pressure sensor 612 is connected to an external pressure sensor data acquisition system 613. The system acquires data from the pressure sensor data acquisition system 613 and calculates the feedback impact force F of the tunnel structure model 607. c-max :

[0122] F c-max =F zd -(m z +m p g;

[0123] in:

[0124] F zd The maximum vertical reaction force at the bottom of the support pier 611 of the tunnel when the drop hammer 601 impacts;

[0125] m p The mass of the shed structure model 607;

[0126] g is the acceleration due to gravity.

[0127] S9: By comparing the values ​​of instantaneous impact force, response impact force, and feedback impact force and judging the error, the response impact force is calibrated to obtain the final impact force.

[0128] The response impact force is a design parameter used to calculate and determine whether a structure can continue to serve after being subjected to an impact. The instantaneous impact force and the feedback impact force are calibrations for the structural response impact force. Since the impact force initially transforms into gravitational potential energy and then decays as the structure's dynamic response and deformation dissipate energy, the theoretical relationship is instantaneous impact force > response impact force > feedback impact force. Analysis of multiple sets of experimental data shows that the difference between the three different inverted impact force values ​​is less than 20%.

[0129] Based on the experimental data, an impact force value was determined. This value was then applied to the rockfall-affected engineering entity to verify and determine the safety of the engineering structure for continued service.

[0130] This step includes:

[0131] S901: Numerical comparison of instantaneous impact force, responsive impact force, and feedback impact force, satisfying...

[0132] F a-max >F b-max >F c-max ;

[0133] S902: Error judgment is performed on instantaneous impact force, response impact force, and feedback impact force, satisfying...

[0134] and

[0135] S903: Repeated numerical comparison and error judgment, based on the response impact force F extracted from multiple sets of data. b-max Calibration, forming the final impact force F max This value is then used to calculate the safety of the engineering structure subjected to falling rock impacts and to determine its subsequent service safety.

[0136] The above methods also include:

[0137] After constructing the tunnel structure model 607, a buffer layer enclosure 606 is poured on top of the tunnel structure model 607, and a buffer layer 605 is laid inside the buffer layer enclosure 606. When the drop hammer 601 is released, it impacts the buffer layer 605. The buffer layer 605 can be sand, rubber, or EPS with a thickness not exceeding 30cm. Its function is to reduce the stiffness of the drop hammer, which is greater than the stiffness of falling rocks during a disaster, so that the stiffness of the drop hammer is reduced to be similar to that of falling rocks.

[0138] Example:

[0139] The following calculations, based on data from one set of experiments, further illustrate this method:

[0140] 1) Test conditions: The drop hammer diameter is 1m, the weight is 1.4t, the top of the shed is covered with a 30cm thick EPS buffer layer, and the drop point is 7.3m above the top of the buffer layer. According to the gravitational potential energy formula, the impact energy of contacting the shed structure is:

[0141] E0 = m z gh = 1.4 x 9.8 x 3.65 = 50 kJ

[0142] This method converts 50kJ of energy into impact force to determine structural safety.

[0143] 2) Extraction of results from accelerometer 603, such as Figure 4 The chart shows that the maximum acceleration of the impact occurred at approximately 0.06 s, with a peak acceleration of 208 m / s². 2 ,but

[0144] F a-max =m z ×a max =1.4 x 208 = 291 kN

[0145] 3) The strain of the steel bar measured by the 609 resistance strain gauge was 1200 x 10⁻⁶. -6 The elastic modulus E of HRB400 steel bars is a constant, i.e., 210 GPa.

[0146] σ z =ε max ×E=1200×10 -6 ×210=252MPa

[0147] Using a mature finite element analysis program, it can be calculated that the steel reinforcement stress can reach 252 MPa when the structure is subjected to an impact force of 273 kN, i.e., F. b-max =273kN < F a-max =291kN, the data is reasonable.

[0148] 4) The four pressure sensors (612) measured a column base reaction force of 102 kN. The self-weight of the shed is 15 tons. Therefore...

[0149] F c-max =F zd -(m z +m p )g=4×102-(1.4+15)×9.8=247kN

[0150] F c-max =247kN < F b-max =273kN

[0151] 5) It can be determined that F in this set of data b-max The value is reasonable, so F b-maxDetermined as the final impact force F max Then, this value is used to check the safety of the engineering structure subjected to the impact of falling rocks.

[0152] The method of the present invention has the following characteristics:

[0153] (1) The method of restoring the project after the disaster is reliable and has strong reference value for the safety assessment of the original project.

[0154] The process of a rockfall impacting a structure is essentially a conversion between the rock's gravitational potential energy and kinetic energy. While the size and location of falling rocks vary greatly in engineering practice, they can all be compared using three parameters: gravitational potential energy (mass), gravitational acceleration, and height. This allows for an equivalent reconstruction of the energy generated when the structure withstands the impact, making the impact reconstruction method relatively reliable. Furthermore, only by extracting the rockfall impact force under the same impact energy can the structural safety assessment be truly reliable.

[0155] (2) The impact of falling rocks is an instantaneous dynamic process. The results of single test inversion of impact force are highly discrete. The method of upgrading to three inversion impact force values ​​can more reliably calibrate the impact force conclusion.

[0156] Traditional impact force testing methods calculate the impact force by measuring the acceleration at the moment of contact and then calculating it based on the weight of the falling hammer. When collecting multiple sets of data, the sphere needs to be constantly moved and released for testing. If the impact force is large and the structural components are damaged, a backup structure needs to be installed. Furthermore, the accelerometer sensor needs to be sent to the factory for inspection and calibration before each test. This testing method is time-consuming, costly, and lacks methods to corroborate the impact force value. This invention proposes three impact force methods: inverting the impact force of the rockfall structure from the strain of the reinforcing steel, inverting the impact force at the moment of contact from the acceleration, and inverting the impact force of the rockfall support feedback from the pressure sensor. After calibration and verification using these three methods, the reliability is significantly improved.

[0157] This invention employs the gravitational potential energy similarity theory, utilizing the free-fall motion resulting from the combination of the weight of the falling hammer and its drop height to simulate the impact energy of an engineering structure subjected to falling rocks. Using conventional building materials and testing equipment, the method of this invention can measure and inversely derive the instantaneous impact force upon rockfall contact, the structural response impact force, and the feedback impact force from rockfall support. Finally, after impact force calibration, the final structural impact force value is used as an external parameter for assessing the structure's continued service safety. The testing and calibration method of this invention is simple to implement, elevating previous qualitative analysis to quantitative analysis, and can serve as an important reference for determining the subsequent service safety of structures such as sheds, bridges, and buildings after being subjected to falling rock impacts.

[0158] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A test calibration method for quantifying the impact force of falling rocks on a tunnel structure, characterized in that: The method includes: Construct a structural model of the shed / cave (607); Resistance strain gauges (609) are pre-installed in the shed structure model (607); Pressure sensors (612) are pre-installed at the bottom of the shed structure model (607); A drop hammer (601) is suspended above the shed structure model (607), and an acceleration sensor (603) is installed on the drop hammer (601); Release the drop hammer (601). When the drop hammer (601) impacts the tunnel structure model (607), acquire the data collected by the resistance strain gauge (609), pressure sensor (612) and acceleration sensor (603). Using the data collected by the accelerometer (603), the instantaneous impact force when the drop hammer (601) comes into contact with the tunnel structure model (607) is calculated; The response impact force of the tunnel structure model (607) is calculated using the data collected by the resistance strain gauge (609); Using the data collected by the pressure sensor (612), the feedback impact force of the tunnel structure model (607) is calculated; By comparing and judging the values ​​of instantaneous impact force, response impact force, and feedback impact force, the response impact force is calibrated to obtain the final impact force.

2. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 1, characterized in that: Constructing a structural model of the shed (607), including: The shed structure model (607) is a reinforced concrete structure with a mesh of shed reinforcement (608) inside to resist bending, and the bottom of both sides is supported by shed supports (611).

3. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 2, characterized in that: Resistance strain gauges (609) are pre-installed within the shed structure model (607), including: When tying the reinforcing bars (608) of the shed, resistance strain gauges (609) are tied at the reinforcing bars in typical locations that bear structural impact, and then the shed structure concrete is poured. Typical locations include the mid-span, quarter-span, and fulcrum.

4. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 3, characterized in that: Pressure sensors (612) are pre-installed at the bottom of the shed structure model (607), including: A pressure sensor sleeve is reserved at the bottom of the support pier (611), and a pressure sensor (612) is installed at the pressure sensor sleeve.

5. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 4, characterized in that: A drop hammer (601) is suspended above the tunnel structure model (607), and an acceleration sensor (603) is installed on the drop hammer (601), including: The surface of the drop hammer (601) is a steel plate shell, and the inside is filled with concrete; Pre-embed steel strand suspension rope (614) before concrete pouring; The steel strand suspension rope (614) is suspended from the tower hook (602); A groove is reserved on the top of the drop hammer (601), and an acceleration sensor (603) is embedded in the groove.

6. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 5, characterized in that: Using data collected by the accelerometer (603), the instantaneous impact force at which the drop hammer (601) contacts the tunnel structure model (607) is calculated, including: The accelerometer (603) is connected to an externally configured acceleration data acquisition system (604); Acquire the data collected by the acceleration data acquisition system (604) and calculate the instantaneous impact force F when the drop hammer (601) contacts the tunnel structure model (607). a-max : F a-max =m z ×a max ; in: v z The instantaneous velocity of the impact of the falling hammer (601) on the tunnel structure model (607); T is the time from the release of the drop hammer (601) to the impact of the tunnel structure model (607); a i The acceleration time history of the drop hammer (601) from release to the shed structure model (607); m z The mass of the falling hammer (601); a max The maximum acceleration time history of the impact of the falling hammer (601) on the tunnel structure model (607) is given.

7. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 6, characterized in that: Using data collected by a resistance strain gauge (609), the response impact force of the tunnel structure model (607) is calculated, including: The resistance strain gauge (609) is connected to an external strain data acquisition system (610); Acquire the data collected by the strain data acquisition system (610) and calculate the response impact force F of the tunnel structure model (607). b-max : s z =e max ×E; F b-max =s z ×JW z ; in: σ z The maximum stress of the 608 steel reinforcement in the shed opening; ε max The maximum stress was measured for the reinforcing steel (608) in the shed opening; E is the elastic modulus of the steel reinforcement; JW z It is the product of the moment conversion factor and the section bending stiffness.

8. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 7, characterized in that: Using the data collected by the pressure sensor (612), the feedback impact force of the tunnel structure model (607) is calculated, including: The pressure sensor (612) is connected to an externally installed pressure sensor data acquisition system (613); Acquire the data collected by the pressure sensor data acquisition system (613) and calculate the feedback impact force F of the tunnel structure model (607). c-max : F c-max =F zd -(m z +m p )g; in: F zd The maximum vertical reaction force at the bottom of the tunnel support pier (611) when the drop hammer (601) impacts; m p The quality of the shed structure model (607); g is the acceleration due to gravity.

9. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 8, characterized in that: By comparing and judging the values ​​of instantaneous impact force, response impact force, and feedback impact force, the response impact force is calibrated to obtain the final impact force, including: Numerical comparisons were made of instantaneous impact force, response impact force, and feedback impact force to meet the requirements. F a-max >F b-max >F c-max ; Error judgment is performed on instantaneous impact force, response impact force, and feedback impact force to meet the requirements. and Repeated numerical comparisons and error assessments were performed, and the response impact force F was determined by extracting data from multiple sets of data. b-max Calibration, forming the final impact force F max .

10. The test calibration method for quantifying the impact force of falling rocks on a tunnel structure according to claim 1, characterized in that: The method further includes: After constructing the shed structure model (607), a buffer layer enclosure (606) is poured on top of the shed structure model (607), and a buffer layer (605) is laid inside the buffer layer enclosure (606); When the drop hammer (601) is released, it impacts the buffer layer (605).

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