Experimental device and experimental method for obtaining the impact load characteristics of demolished collapsed bodies touching the ground

Abstract

The present invention relates to the technical field of physical model test devices for obtaining the impact load characteristics of collapsed bodies touching the ground, and specifically to an experimental device and an experimental method for obtaining the impact load characteristics of collapsed bodies touching the ground during demolition, including a collapsed body load model, a model test box, a loading implementation device and a monitoring and measurement system, wherein the model test box includes a test box, foam is arranged on the outside of the test box, and two layered ground structures of "hard on top and soft on bottom" and "soft on top and hard on bottom" are arranged inside the test box. The device can simply and effectively simulate the impact of collapsed bodies touching the ground during blasting demolition of high-rise and tall structures and quantitatively observe their load characteristics, solving the problems of difficulty in testing the impact load characteristics of collapsed bodies touching the ground during blasting demolition of high-rise and tall structures, and lack of measured data and experimental support for theoretical research on load characteristics, and providing a theoretical basis and experimental support for the safety of blasting demolition of high-rise and tall structures and the safety protection design of protected objects.

Description

Technical Field

[0001] The invention relates to the technical field of physical model test devices for acquiring the impact load characteristics of a collapsed body touching the ground, and in particular to an experimental device and an experimental method for acquiring the impact load characteristics of a collapsed body touching the ground. Background Art

[0002] Blasting demolition has become the preferred method for demolishing high-rise and towering structures in complex environments due to its advantages of safety, efficiency, economy, and environmental protection. During the blasting demolition process, the impact of the structure collapsing and touching the ground and its vibration may cause damage to important protection targets such as adjacent buildings (structures), facilities and equipment, underground pipelines, and subway tunnels, which is the most prominent harmful effect of blasting demolition projects. Therefore, in the demolition blasting design stage, it is necessary to predict and verify the impact load characteristics of the collapsed body touching the ground, the particle vibration velocity at the location of the adjacent protection target, and the dynamic response characteristics of the structure, and formulate safe and effective protection measures.

[0003] However, in the prior art, there is no corresponding experimental device disclosed to provide theoretical research, and the existing impact load characteristics cannot be accurately obtained and studied. Summary of the invention

[0004] In response to the problem, the present invention provides an experimental device for obtaining the impact load characteristics of a collapsed body touching the ground when it is demolished, including a collapsed body load model, a model test box, a loading implementation device and a monitoring and measurement system. The model test box includes a test box, foam is arranged on the outside of the test box, and two layered ground structures, "hard on top and soft on bottom" and "soft on top and hard on bottom", are arranged in the test box; the loading test device is connected to the collapsed body load model, the model test box is located below the loading test device, and the monitoring and measurement system is installed on the loading test device.

[0005] As a further technical solution of the present invention, there are three contact modes between the collapsed body in the collapsed body load model and the soil when the collapsed body touches the ground: plane contact, edge contact and arc surface contact.

[0006] As a further technical solution of the present invention, the "hard on top and soft on bottom" layered ground structure is: a concrete panel is arranged in the test box, and a silty clay layer is arranged on the lower side of the concrete panel; the "soft on top and hard on bottom" layered ground structure is: a silty clay layer is arranged in the test box, and crushed stone soil is arranged on the lower side of the silty clay layer.

[0007] As a further technical solution of the present invention, the loading test device includes a small gantry crane, a fixed pulley is installed on the small gantry crane, a main cable passes through the fixed pulley, one end of the main cable is connected to a winch, the other end of the main cable is connected to a connecting hook, and the connecting hook is connected to the collapse body load model.

[0008] As a further technical solution of the present invention, the monitoring and measuring system includes an accelerometer, an earth pressure gauge, an earth displacement gauge, a strain gauge, a dynamic signal acquisition instrument, a laser transmitter, a photoelectric receiving device, a ruler and a high-speed camera. Three groups of measuring points are arranged radially along the hammer drop point in the test box, each group of measuring points includes a dynamic strain test point on the concrete surface, the strain gauges are arranged at the dynamic strain test points, the earth pressure gauge, the displacement gauge and the accelerometer are evenly arranged along the depth direction of the test box, two groups of laser transmitters and photoelectric receiving devices are symmetrically arranged on the small gantry crane, a ruler is placed on one side of the test box, and a high-speed camera is arranged directly in front of the test box.

[0009] An experimental method based on the above-mentioned experimental device for obtaining the impact load characteristics of demolished collapsed bodies touching the ground comprises the following steps:

[0010] 1) Production of the test box and arrangement of the monitoring and measurement system: Two layered ground structures, "hard on top and soft on bottom" and "soft on top and hard on bottom", are arranged in the test box. Considering the similarity theory of the model test and the actual operability of the test, the similarity scale of the basic physical quantities is calculated, and a typical stratum model is selected to produce a three-dimensional scaled model similar to the two typical strata; three groups of measuring points are arranged radially along the drop hammer point in the test box, each group of measuring points includes a dynamic strain test point on the concrete surface, and the strain gauges are arranged at the dynamic strain test points. Earth pressure gauges, displacement gauges and accelerometers are evenly arranged along the depth direction of the test box, two groups of laser transmitters and photoelectric receiving devices are symmetrically arranged on the small gantry crane, a ruler is placed on one side of the test box, and a high-speed camera is arranged in front of the test box;

[0011] 2) Selection of collapse body load model: In blasting demolition projects, collapse bodies of high-rise buildings are of different sizes and irregular shapes, resulting in different contact modes between collapse bodies and soil when they touch the ground. In the collapse body load model, there are three types of contact modes between collapse bodies and soil when they touch the ground: plane contact, edge contact, and arc contact. Considering the time difference between different collapse bodies when they touch the ground, impact load forms with the same touch-ground mode and different landing heights and touch-ground load forms with different landing heights and different contact modes are designed.

[0012] 3) Model loading: After installing the test box, the collapse load model is lifted by the loading test device, and the rising height of the collapse load model is measured by a ruler;

[0013] 4) Experimental testing and data recording: By selecting different collapse load models and controlling the load drop height to conduct ground impact tests, the failure forms, deformation characteristics, and dynamic earth response characteristic parameters of different ground structures under different ground load conditions, such as acceleration, dynamic earth pressure, and dynamic stress, are obtained.

[0014] As a further technical solution of the present invention, the preparation of the test box in step 1) specifically includes the following steps:

[0015] A. Determine the similarity ratio

[0016] According to the similarity criteria of the first and second similarity theories, the parameter design is carried out, and the geometric similarity ratio of the prototype geometric dimensions and the device geometric dimensions in the actual project is determined to be L=10. According to the geometric similarity ratio, the ground size and depth of the model are designed as 1 / 10 of the prototype size; the gravity acceleration similarity ratio Cg=1, the density similarity ratio Cρ=1, and the bulk density similarity ratio Cγ=1. Based on the geometric similarity ratio and bulk density similarity ratio, the full similarity of Poisson's ratio and friction angle is achieved, and the elastic modulus is designed according to the elastic modulus L of the prototype structural material; at the same time, according to the dimensional relationship, the collapse load mass and the collapse load speed are guaranteed to be similar, and the soil layer similarity ratio is determined as follows:

[0017] Geometric similarity ratio: C L =L;

[0018] Bulk density similarity ratio: Cγ=1;

[0019] Pressure similarity ratio C ξ =C γ ×C L ;

[0020] Concentration force similarity ratio ψ=C γ ×C L 3 ;

[0021] Stress similarity ratio C σ =L;

[0022] Displacement similarity ratio Cs = C L ;

[0023] B. Make a model test box

[0024] Taking the actual prototype as a reference, and based on the dynamic boundary effect and elastic wave transmission speed, the model area should be more than 5 times the main action area of ​​the load. Considering that the longest side length of the rectangular block and triangular prism block load is not less than 300mm, the radius of the large sphere is not less than 100mm, the test platform size is 1000mm×1000mm, and the length, width and height of the model test box are all 900mm. The four sides of the test box are made of steel plates. After mortar finishing, 3cm thick sponges are pasted on each side. According to the set geometric similarity ratio and the actual prototype as a reference, The landfill positions of different strata are marked on the inner side of the steel plate of the test box. In the "concrete panel-silty clay layer" with hard upper and soft lower strata, the silty clay layer is located at the bottom of the test box with a thickness of 850mm, and the concrete panel is located at the upper part of the silty clay layer with a thickness of 50mm. The dimensions are marked in test box A, and a model test box is made according to the above requirements; in the "silty clay layer-gravel soil" with soft upper and hard lower strata, the gravel soil is located at the bottom of the model test box with a thickness of 500mm, and the silty clay layer is located at the top of the test box with a thickness of 400mm. The dimensions are marked in test box B, and a model test box is made according to the above requirements;

[0025] C. Making soil materials

[0026] The weighted average density of the actual soil layer is calculated according to the weighted average algorithm, and the physical parameters of the similar materials of the soil layer in the model test are obtained according to the determined similarity ratio value. The soil layers are placed in the prepared model test box for hammer compaction, and the collapse point is set in advance.

[0027] As a further technical solution of the present invention, the selection operation steps of the collapse body load model in step 2) are:

[0028] The load is classified into three types according to the contact modes of the actual common collapse body with the soil when it touches the ground: plane contact, edge contact, and arc surface contact. That is, rectangular blocks, triangular prism blocks, and spherical blocks are used. The weight of each block is 9kg, 15kg, and 21kg. At the same time, considering that the collapse body load touches the ground for multiple continuous impacts, three small rectangular blocks, three small triangular prism blocks, and three small spherical blocks are also designed. Each small block weighs 3kg, 5kg, and 7kg. Three small blocks of the same type are set and fall at different heights at the same time.

[0029] Consider controlling a single variable factor during the test. At the beginning of the test, a certain collapse load model is tested first, other conditions are kept constant, and the mass of the collapse load model is changed;

[0030] Secondly, the mass of the collapse load model is controlled to be constant, the drop height is changed, and then other quantities are controlled to be constant and the model test box is changed;

[0031] Repeat the above steps for another form of collapse body load model; at the same time, considering that the collapse body load model has the characteristics of multiple continuous impacts when touching the ground, and there is a certain time difference between the multiple impacts, the collapse body load models of different forms are subjected to simultaneous drop tests with a height difference of 10 cm;

[0032] In addition, considering the complexity of the collapse process of actual blasting and demolition projects, a small rectangular model, a triangular prism model and a spherical model can be selected to fall to the ground at the same time, so as to obtain the failure form and dynamic response characteristics of the ground structure model under the corresponding collapse conditions.

[0033] As a further technical solution of the present invention, the operation steps of model loading in step 3) are:

[0034] A. Place the test box on a level ground;

[0035] B. Select the collapse load model and hang it on the connecting hook through a thin rope. Raise the collapse load model to fixed heights of 0.5m, 1.0m, and 1.5m by turning the handle of the hand winch to ensure that the surface of the collapse load model is level with the ground; turn on the test instrument, adjust the initial state of the test instrument, and prepare for test records;

[0036] C. Disconnect the thin rope connecting the hook and the collapse load model to allow the collapse load model to fall freely. By controlling a single variable, change the load height, load mass, load type, load contact type, and ground structure in turn and repeat the above test.

[0037] As a further technical solution of the present invention, the operating steps of the test and data recording in step 4) are:

[0038] A. During the casting process of the collapse load model, the collapse point is pre-set, and three groups of measuring points are arranged along the radial direction of the collapse point. The horizontal distances of the measuring points are 0.2m and 0.4m respectively. A group of accelerometers, earth pressure gauges, and soil displacement gauges are buried every 0.2m from the top of the collapse load model. Representative measuring points should be arranged at the interface between the soft and hard soil layers. The arrangement of the strain monitoring points, i.e. the strain gauges, is bonded to the layered interface when the collapse load model is cast in layers. The entire monitoring point burying process is completed during the casting and production stage of the collapse load model.

[0039] B. At the same time, a soil displacement meter is installed on the surface of the collapse body load model to record the displacement of the collapse body. At the same time, a laser transmitter and a photoelectric receiving device are installed around the device to measure the movement speed of the collapse body load model. A high-speed camera is used to observe the falling movement characteristics of the collapse body load model;

[0040] C. Before the collapse load model falls, turn on the recording instruments at all monitoring points, record the data at the initial monitoring points, and keep all monitoring and recording instruments turned on to continuously monitor the entire process of the ground impact test until all monitoring data are stable and the monitoring process is terminated.

[0041] The present invention has the following beneficial effects:

[0042] 1. This test device and method overcomes the difficulty in observing the ground contact vibration effect in actual engineering. At the same time, it takes into account factors such as different ground contact modes, different forms of collapse loads, different ground contact energies, and different types of ground structures. To a large extent, it realizes the principle of controlling a single variable in a multivariable system.

[0043] 2. Through the test device measurement system, the dynamic response data of the ground structure, such as dynamic strain, dynamic earth pressure, soil acceleration and displacement, under the impact condition of the collapse body touching the ground during the demolition of high-rise buildings by blasting are fully acquired, providing theoretical basis and experimental support for the theoretical research on the impact load of the collapse body touching the ground and the safety protection design;

[0044] 3. This device can simply and effectively simulate the quantitative observation of the impact of collapsed bodies touching the ground and their load characteristics during blasting demolition of high-rise and tall buildings. It solves the difficult problems of testing the load characteristics of collapsed bodies touching the ground during blasting demolition of high-rise and tall buildings and the lack of measured data and experimental support for theoretical research on load characteristics. It provides a theoretical basis and experimental support for the safety of blasting demolition of high-rise and tall buildings and the safety protection design of protected objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0046] Figure 1 is a schematic diagram of a contact load model of the present invention;

[0047] Figure 2 It is a schematic diagram of the overall structure of the test system of the present invention;

[0048] Figure 3 It is a schematic diagram of the soil layer structure in the model test box of the present invention (concrete panel-silty clay layer);

[0049] Figure 4 It is a schematic diagram of the soil layer structure (silty clay layer-gravel soil) in the model test box of the present invention.

[0050] In the figure: 1- load model, 2- test box, 3- small gantry crane, 4- fixed pulley, 5- main cable, 6- hand winch, 7- connecting hook, 8- accelerometer, 9- earth pressure box, 10- soil displacement meter, 11- strain gauge, 12- laser transmitter, 13- photoelectric receiving device, 14- ruler, 15- high-speed camera, 16- foam.

[0051] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0054] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0055] Embodiment 1:

[0056] Combination Figure 1-Figure 4 In an embodiment of the present invention, an experimental device for obtaining the impact load characteristics of a collapsed body touching the ground is provided, comprising a collapsed body load model 1, a model test box, a loading implementation device and a monitoring and measuring system, wherein the model test box comprises a test box 2, a foam 16 is arranged on the outside of the test box 2, and two layered ground structures of "hard on top and soft on bottom" and "soft on top and hard on bottom" are arranged inside the test box 2; the loading test device is connected to the collapsed body load model 1, the model test box is located below the loading test device, and the monitoring and measuring system is installed on the loading test device.

[0057] See also Figure 3 There are three contact modes between the collapsed body in the collapsed body load model 1 and the soil when the collapsed body touches the ground: plane contact, edge contact and arc surface contact.

[0058] See also Figure 4 The "hard on top and soft on bottom" layered ground structure is: a concrete panel is arranged in the test box 2, and a silty clay layer is arranged on the lower side of the concrete panel; the "soft on top and hard on bottom" layered ground structure is: a silty clay layer is arranged in the test box 2, and crushed stone soil is arranged on the lower side of the silty clay layer.

[0059] The loading test device includes a small gantry crane 3, on which a fixed pulley 4 is installed, and a main cable 5 passes through the fixed pulley 4. One end of the main cable 5 is connected to a winch 6, and the other end of the main cable 5 is connected to a connecting hook 7, and the connecting hook 7 is connected to the collapse body load model 1.

[0060] The monitoring and measuring system includes an accelerometer 8, an earth pressure gauge 9, an earth displacement gauge 10, a strain gauge 11, a dynamic signal acquisition instrument, a laser transmitter 12, a photoelectric receiving device 13, a ruler 14 and a high-speed camera 15. Three groups of measuring points are arranged radially along the drop hammer point on the test box 2, each group of measuring points includes a dynamic strain test point on the concrete surface, and the strain gauge 11 is arranged at the dynamic strain test point. The earth pressure gauge 9, the displacement gauge 10 and the accelerometer 8 are evenly arranged along the depth direction of the test box 2. Two groups of laser transmitters 12 and photoelectric receiving devices 13 are symmetrically arranged on the small gantry crane 3 for measuring the falling speed of the drop hammer. A computer for outputting strain, earth pressure, acceleration, displacement and speed is arranged on one side of the test box 2. A ruler 14 is placed on one side of the test box 2, and a high-speed camera 15 is arranged directly in front of the test box 2.

[0061] Embodiment 2:

[0062] An experimental method based on the above-mentioned experimental device for obtaining the impact load characteristics of demolished collapsed bodies touching the ground comprises the following steps:

[0063] 1) Production of the test box 2 and arrangement of the monitoring and measurement system: Two layered ground structures, "hard on top and soft on bottom" and "soft on top and hard on bottom", are arranged in the test box 2. Considering the similarity theory of the model test and the actual operability of the test, the similarity scale of the basic physical quantities is calculated, and a typical stratum model is selected to produce a three-dimensional scaled model similar to the two typical strata; three groups of measuring points are arranged radially along the hammer drop point in the test box 2, each group of measuring points includes a dynamic strain test point on the concrete surface, and the strain gauges 11 are arranged at the dynamic strain test points. Earth pressure gauges 9, displacement meters 10 and accelerometers 8 are evenly arranged along the depth direction of the test box 2, two groups of laser transmitters 12 and photoelectric receiving devices 13 are symmetrically arranged on the small gantry crane 3, a ruler 14 is placed on one side of the test box 2, and a high-speed camera 15 is arranged directly in front of the test box 2;

[0064] 2) Selection of collapse body load model 1: In blasting demolition projects, collapse bodies of high-rise structures are of different sizes and irregular shapes, resulting in different contact modes between collapse bodies and soil when they touch the ground. In collapse body load model 1, there are three types of contact modes between collapse bodies and soil when they touch the ground: plane contact, edge contact, and arc contact. Considering the time difference between different collapse bodies when they touch the ground, impact load forms with the same touch-ground mode and different landing heights and touch-ground load forms with different landing heights and different contact modes are designed.

[0065] 3) Model loading: After the test box 2 is installed, the collapse load model 1 is lifted by the loading test device, and the rising height of the collapse load model 1 is measured by the ruler 14. The collapse load models 1 with different masses and multiple collapse load models 1 of the same type falling from different heights can be used to study the deformation and dynamic response characteristics of different stratum structures under different impact energies, different ground contact modes and different collapse time intervals;

[0066] 4) Experimental testing and data recording: By selecting different collapse load models 1 and controlling the load drop height to conduct ground impact tests, the failure forms, deformation characteristics, and dynamic earth response characteristic parameters of acceleration, dynamic earth pressure, and dynamic stress of different ground structures under different ground load conditions are obtained.

[0067] The preparation of the test box 1 in step 1) specifically includes the following steps:

[0068] A. Determine the similarity ratio

[0069] According to the similarity criteria of the first and second similarity theories, the parameter design is carried out, and the geometric similarity ratio of the prototype geometric dimensions and the device geometric dimensions in the actual project is determined to be L=10. According to the geometric similarity ratio, the ground size and depth of the model are designed as 1 / 10 of the prototype size; the gravity acceleration similarity ratio Cg=1, the density similarity ratio Cρ=1, and the bulk density similarity ratio Cγ=1. Based on the geometric similarity ratio and bulk density similarity ratio, the full similarity of Poisson's ratio and friction angle is achieved, and the elastic modulus is designed according to the elastic modulus L of the prototype structural material; at the same time, according to the dimensional relationship, the collapse load mass and the collapse load speed are guaranteed to be similar, and the soil layer similarity ratio is determined as follows:

[0070] Geometric similarity ratio: C L =L;

[0071] Bulk density similarity ratio: Cγ=1;

[0072] Pressure similarity ratio C ξ =C γ ×C L ;

[0073] Concentration force similarity ratio ψ=C γ ×C L 3 ;

[0074] Stress similarity ratio C σ =L;

[0075] Displacement similarity ratio Cs = C L ;

[0076] B. Make a model test box

[0077] Taking the actual prototype as a reference, and based on the dynamic boundary effect and elastic wave transmission speed, the model area should be more than 5 times the main action area of ​​the load. Considering that the longest side length of the rectangular block and triangular prism block load is not less than 300mm, the radius of the large sphere is not less than 100mm, the test platform size is 1000mm×1000mm, and the length, width and height of the model test box are all 900mm. The four sides of the test box 2 are made of steel plates. After mortar finishing, each is pasted with 3cm Thickness of sponge, according to the set geometric similarity ratio, with the actual prototype as reference, mark the different stratum landfill positions on the inner side of the steel plate of test box 2, among which the silty clay layer in the upper hard and lower soft stratum of "concrete panel-silty clay layer" is located at the bottom of test box 2, with a thickness of 850mm, and the concrete panel is located on the upper part of the silty clay layer, with a thickness of 50mm. Mark the size in test box A, and make a model test box according to the above requirements; the gravel soil in the upper soft and lower hard stratum of "silty clay layer-gravel soil" is located at the bottom of the model test box, with a thickness of 500mm, and the silty clay layer is located at the top of test box 2 with a thickness of 400mm. Mark the size in test box B, and make a model test box according to the above requirements;

[0078] C. Making soil materials

[0079] The weighted average density of the actual soil layer is calculated according to the weighted average algorithm, and the physical parameters of the similar materials of the soil layer in the model test are obtained according to the determined similarity ratio value. The soil layers are placed in the prepared model test box for hammer compaction, and the collapse point is set in advance.

[0080] The selection operation steps of the collapse body load model 1 in step 2) are as follows:

[0081] The load is classified into three types according to the contact mode between the actual common collapse body and the soil body when it touches the ground: plane contact, edge contact, and arc surface contact. That is, rectangular blocks, triangular prism blocks, and spherical blocks are used. The weight of each block is 9kg, 15kg, and 21kg. At the same time, considering that the collapse body load touches the ground for multiple continuous impacts, three small rectangular blocks, three small triangular prism blocks, and three small spherical blocks are also designed. Each small block weighs 3kg, 5kg, and 7kg. Three small blocks of the same type are set and fall at different heights at the same time to achieve the effect of time difference when different collapse loads touch the ground. In this experiment, the height difference is 10cm; in order to simulate the energy impact caused by the falling height, the falling heights are selected as 0.5m, 1m, and 1.5m, and the load lifting height is changed with a ruler 14;

[0082] Consider controlling a single variable factor during the test. At the beginning of the test, a test of a collapse load model 1 is first carried out, other conditions are kept unchanged, and the mass of collapse load model 1 is changed;

[0083] Secondly, the mass of the collapse load model 1 is controlled to be constant, the falling height is changed, and then other quantities are controlled to be constant and the model test box is changed;

[0084] Repeat the above steps for the collapse body load model 1 of another form; at the same time, considering that the collapse body load model 1 has the characteristics of multiple continuous impacts when touching the ground, and there is a certain time difference between the multiple impacts, the collapse body load model 1 of different forms is subjected to a simultaneous drop test with a height difference of 10 cm;

[0085] In addition, considering the complexity of the collapse process of actual blasting and demolition projects, a small rectangular model, a triangular prism model and a spherical model can be selected to fall to the ground at the same time, so as to obtain the failure form and dynamic response characteristics of the ground structure model under the corresponding collapse conditions.

[0086] The operation steps of model loading in step 3) are:

[0087] A. Place the test box 2 on a horizontal ground;

[0088] B. Select the collapse load model 1 and hang it on the connecting hook 7 through a thin rope. Raise the collapse load model 1 to fixed heights of 0.5m, 1.0m, and 1.5m by turning the handle of the hand winch 6 to ensure that the surface of the collapse load model 1 is level with the ground; turn on the test instrument, adjust the initial state of the test instrument, and prepare for test records;

[0089] C. Disconnect the thin rope connecting the hook 7 and the collapse load model 1, and let the collapse load model 1 fall freely. By controlling a single variable, change the load height, load mass, load type, load contact type, and ground structure in turn, and repeat the above test.

[0090] The operation steps of the test and data recording in step 4) are as follows:

[0091] A. During the pouring process of the collapse load model 1, the collapse point is pre-set, and three groups of measuring points are arranged along the radial direction of the collapse point. The horizontal distances of the measuring points are 0.2m and 0.4m respectively. A group of accelerometers 8, soil pressure gauges 9, and soil displacement gauges 10 are buried every 0.2m from the top of the collapse load model 1 downward. Representative measuring points should be arranged at the interface between the soft and hard soil layers. The arrangement of the strain monitoring point, i.e., the strain gauge 11, is bonded to the layered interface when the collapse load model 1 is poured in layers. The entire monitoring point burying process is completed during the pouring and manufacturing stage of the collapse load model 1.

[0092] B. A soil displacement meter 10 is installed on the surface of the collapse body load model 1 to record the displacement of the collapse body. A laser transmitter 12 and a photoelectric receiving device 13 are installed around the device to measure the movement speed of the collapse body load model 1. A high-speed camera 15 is used to observe the falling movement characteristics of the collapse body load model 1.

[0093] C. Before the collapse load model 1 falls, turn on the recording instruments at all monitoring points, record the data of the initial monitoring points, and keep all monitoring and recording instruments turned on to continuously monitor the entire process of the ground impact test until all monitoring data are stable, and then end the monitoring process.

[0094] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. The experimental device for obtaining the impact load characteristics of the collapsed body touching the ground is characterized by: The invention comprises a collapse body load model (1), a model test box, a loading implementation device and a monitoring and measuring system, wherein the model test box comprises a test box (2), the outer side of the test box (2) is provided with foam (16), and the inside of the test box (2) is provided with two layered ground structures, namely, "upper hard and lower soft" and "upper soft and lower hard"; the loading implementation device is connected to the collapse body load model (1), the model test box is located below the loading implementation device, and the monitoring and measuring system is installed on the loading implementation device; The loading implementation device comprises a small gantry crane (3), a fixed pulley (4) is installed on the small gantry crane (3), a main cable (5) passes through the fixed pulley (4), one end of the main cable (5) is connected to a winch (6), and the other end of the main cable (5) is connected to a connecting hook (7), and the connecting hook (7) is connected to the collapse body load model (1); The monitoring and measuring system comprises an accelerometer (8), an earth pressure gauge (9), an earth displacement gauge (10), a strain gauge (11), a dynamic signal acquisition instrument, a laser transmitter (12), a photoelectric receiving device (13), a ruler (14) and a high-speed camera (15); three groups of measuring points are arranged radially along the hammer drop point on the test box (2); each group of measuring points comprises a dynamic strain test point on the concrete surface; the strain gauge (11) is arranged at each dynamic strain test point; the earth pressure gauge (9), the displacement gauge (10) and the accelerometer (8) are evenly arranged along the depth direction of the test box (2); two groups of laser transmitters (12) and the photoelectric receiving device (13) are symmetrically arranged on the small gantry crane (3); a ruler (14) is placed on one side of the test box (2); and a high-speed camera (15) is arranged directly in front of the test box (2); The experimental steps are as follows: 1) Production of the test box (2) and arrangement of the monitoring and measuring system: two layered ground structures, "hard on top and soft on bottom" and "soft on top and hard on bottom", are arranged in the test box (2). Considering the similarity theory of the model test and the actual operability of the test, the similarity scale of the basic physical quantities is calculated and obtained, a typical stratum model is selected, and a three-dimensional scaled model similar to the two typical strata is produced; three groups of measuring points are arranged radially along the hammer drop point in the test box (2), each group of measuring points includes a dynamic strain test point on the concrete surface, and the strain gauges (11) are arranged at the dynamic strain test points; soil pressure gauges (9), displacement gauges (10) and accelerometers (8) are evenly arranged along the depth direction of the test box (2); two groups of laser transmitters (12) and photoelectric receiving devices (13) are symmetrically arranged on the small gantry crane (3); a ruler (14) is placed on one side of the test box (2); and a high-speed camera (15) is arranged directly in front of the test box (2); 2) Selection of collapse body load model (1): In blasting demolition projects, collapse bodies of high-rise buildings are of different sizes and shapes, resulting in different contact modes between collapse bodies and soil when they touch the ground. In collapse body load model (1), there are three types of contact modes between collapse bodies and soil when they touch the ground: plane contact, edge contact, and arc contact. Considering the time difference between different collapse bodies when they touch the ground, impact load forms with the same touch-ground mode and different landing heights and touch-ground load forms with different landing heights and different contact modes are designed. 3) Model loading: After the test box (2) is installed, the collapse load model (1) is lifted by a loading implementation device, and the lifting height of the collapse load model (1) is measured by a ruler (14); 4) Experimental testing and data recording: By selecting different collapse load models (1), controlling the load drop height to conduct ground impact tests, the failure forms and deformation characteristics of different ground structures under different ground load conditions, as well as the dynamic response characteristic parameters of acceleration, dynamic earth pressure, and dynamic stress are obtained; The preparation of the test box (2) in step 1) specifically includes the following steps: A. Determine the similarity ratio According to the similarity criteria of the first and second similarity theories, the parameter design is carried out, and the geometric similarity ratio of the prototype geometric dimensions and the device geometric dimensions in the actual project is determined to be L=10. According to the geometric similarity ratio, the ground size and depth of the model are designed as 1 / 10 of the prototype size; the gravity acceleration similarity ratio Cg=1, the density similarity ratio Cρ=1, and the bulk density similarity ratio Cγ=1. Based on the geometric similarity ratio and bulk density similarity ratio, the full similarity of Poisson's ratio and friction angle is achieved, and the elastic modulus is designed according to the elastic modulus L of the prototype structural material; at the same time, according to the dimensional relationship, the collapse load mass and the collapse load speed are guaranteed to be similar, and the soil layer similarity ratio is determined as follows: Geometric similarity ratio: C L =L; Bulk density similarity ratio: Cγ=1; Pressure similarity ratio C ξ =C γ ×C L ; Concentration force similarity ratio ψ=C γ ×C L 3 ; Stress Similarity Ratio ; Displacement similarity ratio Cs=C L ; B. Make a model test box Taking the actual prototype as a reference, and based on the dynamic boundary effect and elastic wave transmission speed, the model area should be more than 5 times the main action area of ​​the load. Considering that the longest side length of the rectangular block and triangular prism block load is not less than 300mm, the radius of the large sphere is not less than 100mm, the test platform size is 1000mm×1000mm, and the length, width and height of the model test box are all 900mm. The four sides of the test box (2) are made of steel plates, which are polished with mortar and then pasted with 3cm thick sponges. According to the set geometric similarity ratio, taking the actual prototype as a reference, in the test box, The inner side of the steel plate of (2) is marked with different strata landfill positions. In the "concrete panel-silty clay layer" with hard upper and soft lower strata, the silty clay layer is located at the bottom of the test box (2) with a thickness of 850 mm, and the concrete panel is located at the upper part of the silty clay layer with a thickness of 50 mm. The dimensions are marked in the test box A, and a model test box is made according to the above requirements; in the "silty clay layer-gravel soil" with soft upper and hard lower strata, the gravel soil is located at the bottom of the model test box with a thickness of 500 mm, and the silty clay layer is located at the top of the test box (2) with a thickness of 400 mm. The dimensions are marked in the test box B, and a model test box is made according to the above requirements; C. Making soil materials The weighted average density of the actual soil layer is calculated according to the weighted average algorithm, and the physical parameters of the similar materials of the soil layer in the model test are obtained according to the determined similarity ratio value. The soil layers are placed in the prepared model test box for hammer compaction, and the collapse point is set in advance.

2. The experimental device for obtaining the impact load characteristics of demolished collapsed bodies touching the ground according to claim 1, characterized in that: The "hard on top and soft on bottom" layered ground structure is: a concrete panel is arranged in the test box (2), and a silty clay layer is arranged below the concrete panel; the "soft on top and hard on bottom" layered ground structure is: a silty clay layer is arranged in the test box (2), and crushed stone soil is arranged below the silty clay layer.

3. An experimental method for obtaining the characteristics of the impact load of a demolished collapsed body touching the ground, applied to the experimental device for obtaining the characteristics of the impact load of a demolished collapsed body touching the ground as described in any one of claims 1-2, characterized in that: The steps for selecting the collapse load model (1) in step 2) are as follows: The load is classified into three types according to the contact modes of the actual common collapse body with the soil when it touches the ground: plane contact, edge contact, and arc surface contact. That is, rectangular blocks, triangular prism blocks, and spherical blocks are used. The weight of each block is 9kg, 15kg, and 21kg. At the same time, considering that the collapse body load touches the ground for multiple continuous impacts, three small rectangular blocks, three small triangular prism blocks, and three small spherical blocks are also designed. Each small block weighs 3kg, 5kg, and 7kg. Three small blocks of the same type are set and fall at different heights at the same time. When testing, consider controlling a single variable factor. At the beginning of the test, first conduct a test of a collapse load model (1), control other conditions unchanged, and change the mass of the collapse load model (1); Secondly, the collapse body load model (1) keeps the mass constant, changes the drop height, and then controls other quantities constant and changes the model test box; Repeat the above steps for the collapse body load model (1) of another form; at the same time, considering that the collapse body load model (1) has the characteristics of multiple continuous impacts when touching the ground, and there is a certain time difference between the multiple impacts when touching the ground, the collapse body load model (1) of different forms is subjected to a simultaneous drop test with a height difference of 10 cm; In addition, considering the complexity of the collapse process of actual blasting and demolition projects, a small rectangular model, a triangular prism model and a spherical model can be selected to fall to the ground at the same time, so as to obtain the failure form and dynamic response characteristics of the ground structure model under the corresponding collapse conditions.

4. The experimental method according to claim 3, characterized in that The operation steps of model loading in step 3) are: A. Place the test box (2) on a level surface. B. Select a collapse load model (1) and hang it on the connecting hook (7) through a thin rope. Raise the collapse load model (1) to fixed heights of 0.5 m, 1.0 m, and 1.5 m by turning the handle of the hand winch (6) to ensure that the surface of the collapse load model (1) is level with the ground; Turn on the test instrument, adjust the initial state of the test instrument, and prepare test records; C. Disconnect the thin rope connecting the hook (7) and the collapse load model (1), and let the collapse load model (1) fall freely. By controlling a single variable, change the load height, load mass, load type, load contact type, and ground structure in sequence, and repeat the above test.

5. The experimental method according to claim 3, characterized in that: The operation steps of the test and data recording in step 4) are as follows: A. During the pouring process of the collapse load model (1), the collapse point is pre-set, and three groups of measuring points are arranged along the radial direction of the collapse point. The horizontal distances of the measuring points are 0.2m and 0.4m respectively. A group of accelerometers (8), soil pressure gauges (9), and soil displacement gauges (10) are buried every 0.2m from the top of the collapse load model (1). Representative measuring points should be arranged at the interface between the soft and hard soil layers. The strain monitoring points, i.e., the strain gauges (11), are arranged when the collapse load model (1) is poured in layers and bonded to the layer interface. The entire monitoring point burying process is completed during the pouring and manufacturing stage of the collapse load model (1); B. A soil displacement meter (10) is installed on the surface of the collapse body load model (1) to record the displacement of the collapse body. A laser transmitter (12) and a photoelectric receiving device (13) are installed around the device to measure the movement speed of the collapse body load model (1). A high-speed camera (15) is used to observe the falling movement characteristics of the collapse body load model (1); C. Before the collapse load model (1) falls, turn on the recording instruments at all monitoring points, record the data at the initial monitoring point, and keep all monitoring recording instruments turned on to continuously monitor the entire process of the ground impact test until all monitoring data are stable, and then end the monitoring process.

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