CN113432963A - Experimental device and experimental method for obtaining characteristics of touchdown impact load of demolished collapsed body - Google Patents
Experimental device and experimental method for obtaining characteristics of touchdown impact load of demolished collapsed body Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
- G01N3/303—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated only by free-falling weight
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N2203/001—Impulsive
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention relates to the technical field of physical model test devices for acquiring the touchdown impact load characteristics of collapsed bodies, in particular to an acquisition test device for acquiring the touchdown impact load characteristics of the disassembled collapsed bodies and an experimental method thereof. The device can simply and effectively simulate the quantitative observation of the touchdown impact and the load characteristic of the collapsed body demolition blasting of the high-rise structure, solves the problems that the test of the touchdown impact load characteristic of the collapsed body is difficult and the theoretical research of the load characteristic lacks actual measurement data and test support in the blasting demolition process of the high-rise structure, and provides theoretical basis and test support for the safety protection design of the blasting demolition safety and the protection object of the high-rise structure.
Description
Technical Field
The invention relates to the technical field of physical model test devices for acquiring the touchdown impact load characteristics of collapsed bodies, in particular to an experimental device and an experimental method for acquiring the touchdown impact load characteristics of the disassembled collapsed bodies.
Background
The blasting demolition mode has become the preferred mode for demolishing high-rise structures in complex environments due to the advantages of safety, high efficiency, economy, environmental protection and the like. In the blasting demolition process, the impact of structure collapse and vibration thereof can cause damage to important protection targets such as adjacent buildings (structures), facilities and equipment, underground pipelines, subway tunnels and the like, and the blasting demolition process is the most prominent harmful effect of the blasting demolition project. Therefore, in the demolition blasting design stage, the touchdown impact load characteristics of the collapsed body, the particle vibration speed at the position adjacent to the protection target and the dynamic response characteristic of the structure need to be predicted and checked, and safe and effective protective measures need to be made.
However, in the prior art, a corresponding experimental device is not disclosed to provide theoretical research, and the existing impact load characteristics cannot be accurately obtained and researched.
Disclosure of Invention
Aiming at the problems, the invention provides an experimental device for obtaining the touchdown impact load characteristics of demolished falling bodies, which comprises a collapsed body load model, a model test box, a loading implementation device and a monitoring measurement system, wherein the model test box comprises a test box, foam is arranged on the outer side of the test box, and two layered ground structures of 'hard top and soft bottom' and 'soft top and hard bottom' are arranged in the test box; the loading test device is connected with the collapse body load model, the model test box is positioned below the loading test device, and the monitoring and measuring system is installed on the loading test device.
The invention adopts the following further technical scheme: three contact modes of the collapsed body in the collapsed body load model and the soil body are arranged: respectively planar contact, edge contact and cambered surface contact.
The invention adopts the following further technical scheme: the layered ground structure with hard upper part and soft lower part is as follows: a concrete panel is arranged in the test box, and a powdery clay layer is arranged on the lower side of the concrete panel; the layered ground structure with soft upper part and hard lower part is as follows: a powdery clay layer is arranged in the test box, and gravels are arranged on the lower side of the powdery clay layer.
The invention adopts the following further technical scheme: the loading test device comprises a small gantry crane, a fixed pulley is mounted on the small gantry crane, a main cable penetrates through the fixed pulley, one end of the main cable is connected with a winch, the other end of the main cable is connected with a connecting hook, and the connecting hook is connected with the slump load model.
The invention adopts the following further technical scheme: the monitoring and measuring system comprises an accelerometer, a soil pressure gauge, a soil body displacement meter, a strain gauge, a dynamic signal acquisition instrument, a laser emitter, a photoelectric receiving device, a scale and a high-speed camera, three groups of measuring points are radially distributed on the test box along a drop hammer point, each group of measuring points comprises a dynamic strain test point on the surface of concrete, the strain gauge is uniformly distributed on the dynamic strain test point, the soil pressure gauge, the displacement meter and the accelerometer are uniformly distributed along the depth direction of the test box, two groups of laser emitters and the photoelectric receiving device are symmetrically arranged on the small gantry crane, the scale is placed on one side of the test box, and the high-speed camera is arranged right in front of the test box.
An experiment method for obtaining an experiment device based on the characteristic of demolishing the touchdown impact load of a collapsed body comprises the following steps:
1) manufacturing a test box and arranging a monitoring measurement system: the test box is internally provided with two layered ground structures of 'hard top and soft bottom' and 'soft top and hard bottom', the similar theory of model test and the actual operability of the test are considered at the same time, the similar scale of the basic physical quantity is obtained by calculation, a typical stratum model is selected, and a three-dimensional scale model similar to the two typical stratums is manufactured; three groups of measuring points are radially distributed on the test box along the drop hammer point, each group of measuring points comprises dynamic strain test points on the surface of concrete, strain gauges are uniformly distributed on the dynamic strain test points, soil pressure gauges, displacement meters and accelerometers are uniformly distributed 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 scale is arranged on one side of the test box, and a high-speed camera is arranged right in front of the test box;
2) selecting a collapse body load model: in the blasting demolition engineering, the sizes of collapsed bodies are different and the shapes of the collapsed bodies are irregular when a high-rise structure collapses, so that the contact modes of the collapsed bodies with the soil body when the collapsed bodies touch the ground are also different greatly, and three contact modes of the collapsed bodies in the collapsed body load model with the soil body when the collapsed bodies touch the ground are arranged: respectively, plane contact, edge contact and cambered surface contact; meanwhile, the time difference existing when different collapse bodies touch the ground is considered, so that the ground-contact impact load forms with the same ground-contact mode and different ground-contact heights and the ground-contact load forms with different ground-contact heights and different contact modes are designed;
3) model loading application: after the test box is installed, the collapse body load model is lifted through the loading test device, and the lifting height of the collapse body load model is measured through the ruler;
4) test testing and data recording: and controlling the falling height of the load to carry out a ground contact impact test by selecting different collapse body load models, and acquiring the damage forms and deformation characteristics of different ground structures under different ground contact load conditions and the moving soil response characteristic parameters of acceleration, moving soil pressure and dynamic stress.
The invention adopts the following further technical scheme: the manufacturing method of the test box in the step 1) specifically comprises the following steps:
A. determining a similarity ratio
Carrying out parameter design according to a first similarity theory similarity criterion and a second similarity theory similarity criterion, determining that the geometric similarity ratio of the geometric dimension of a prototype and the geometric dimension of a device in actual engineering is L-10, and designing the ground dimension and the depth of the model according to the geometric similarity ratio and 1/10 of the prototype dimension; the gravity acceleration similarity ratio Cg is 1, the density similarity ratio Crho is 1, the volume-weight similarity ratio Cgamma is 1, the geometric similarity ratio and the volume-weight similarity ratio are taken as the basis similarity ratio, the Poisson ratio and the friction angle are completely similar, and the elastic modulus is designed according to the L of the elastic modulus of the prototype structural material; meanwhile, ensuring that the collapse load quality and the collapse load speed are similar according to the dimensional relationship, and determining the soil layer similarity ratio as follows:
geometric similarity ratio: cL＝L；
Volume-weight similarity ratio: c γ ═ 1;
pressure similarity ratio Cξ＝Cγ×CL；
Concentration force similarity ratio psi ═ Cγ×CL 3；
Stress similarity ratio Cσ＝L；
Displacement similarity ratio Cs ═ CL；
B. Test box for making model
Taking an actual prototype as reference, simultaneously according to a dynamic boundary effect and an elastic wave transmission speed, the model area is more than 5 times of the load main action area, considering that the longest side length of the load of a cuboid block and a triangular prism block is not less than 300mm, the radius of a large sphere is not less than 100mm, the size of a test platform is 1000mm multiplied by 1000mm, the length, the width and the height of a model test box model are 900mm, the four sides around the test box are made of steel plate materials, after the polishing treatment by adopting mortar plastering, sponge with the thickness of 3cm is respectively pasted, according to a set geometric similarity ratio, the actual prototype is taken as reference, different stratum landfill positions are marked on the inner side of the steel plate of the test box, wherein a powder clay layer in a soft stratum with hard upper part and soft lower part of a concrete panel-powder clay layer is positioned at the bottom of the test box and has the thickness of 850mm, the concrete panel is positioned at the upper part of the powder clay layer and has the thickness of 50mm, and the size is marked in the test box A, manufacturing a model test box according to the requirements; the method comprises the following steps that (1) gravels in a soft upper and hard lower stratum of a silty clay layer-gravels soil layer are located at the bottom of a model test box and 500mm in thickness, the silty clay layer is located at the top of the test box and 400mm in thickness, the test box B is marked with dimensions, and the model test box is manufactured according to the requirements;
C. making soil layer material
And calculating the weighted average gravity of the actual soil layer according to a weighted average algorithm, solving the physical parameters of the soil layer similar materials in the model test according to the determined similar proportion value, layering the soil layer similar materials into a prepared model test box for hammering and tamping, and presetting a collapse point.
The invention adopts the following further technical scheme: the selection operation steps of the slump body load model in the step 2) are as follows:
the load is summarized into three types of plane contact, edge contact and cambered surface contact according to the actual common contact mode of a collapsed body and a soil body when the collapsed body contacts the ground, namely cuboid blocks, triangular prism blocks and spherical blocks are adopted, the weight of each block is 9kg, 15kg and 21kg, meanwhile, considering that the collapse body load contacts the ground to be multiple continuous impact, three small cuboid blocks, three small triangular prism blocks and three small spherical blocks are also designed, each small block respectively has 3kg, 5kg and 7kg, three small blocks of the same type are arranged, and the three small blocks are located at different heights and fall simultaneously;
during the test, a single variable control factor is considered, when the test is started, a certain collapsed body load model is tested, other conditions are controlled to be unchanged, and the mass of the collapsed body load model is changed;
secondly, controlling the mass of the collapsed body load model to be unchanged, changing the falling height, and then controlling other quantities to be unchanged to change the model test box;
repeating the above steps for a slump body loading model of another form; meanwhile, considering that the collapse body load model has the characteristic of multiple continuous impacts due to the contact impact, and a certain time difference exists due to the multiple contact impacts, the simultaneous falling test with the height difference of 10cm is carried out on the collapse body load models in different forms;
in addition, considering the complexity of the collapse process of the actual blasting demolition engineering, a small cuboid model, a triangular prism model and a spherical model can be selected to fall to the ground simultaneously, so that the damage form and the dynamic response characteristic of the ground structure model under the corresponding collapse condition can be obtained.
The invention adopts the following further technical scheme: the operation steps of applying the model loading in the step 3) are as follows:
A. placing a test box, and placing the test box on a horizontal ground;
B. selecting a collapsed body load model, hanging the collapsed body load model at a connecting hook through a string, and lifting the collapsed body load model to fixed heights of 0.5m, 1.0m and 1.5m by rotating a handle of a hand winch to ensure that the surface of the collapsed body load model is horizontal to the ground; opening a test instrument, adjusting the initial state of the test instrument, and preparing a test record;
C. and disconnecting the connecting hook and the string of the slump body load model to enable the slump body load model to fall freely, sequentially changing the load height, the load mass, the load type, the load grounding type and the ground structure in a single variable control mode, and repeating the test.
The invention adopts the following further technical scheme: the operation steps of the test and the data recording in the step 4) are as follows:
A. in the slump body load model pouring process, setting slump points in advance, arranging three groups of measuring points along the radial direction of the slump points, wherein the horizontal distances of the measuring points are 0.2m and 0.4m respectively, burying a group of accelerometers, soil pressure gauges and soil displacement meters every 0.2m from the top of the slump body load model downwards, arranging representative measuring points at a soft and hard soil layer interface, and arranging strain monitoring points, namely strain gauges, on the layered interface when the slump body load model is poured in layers, wherein the whole monitoring point burying process is completed in the slump body load model pouring manufacturing stage;
B. meanwhile, a soil displacement meter is arranged on the surface of the collapsed body load model and used for recording the displacement of the collapsed body, a laser transmitter and a photoelectric receiving device are arranged around the device and used for measuring the movement speed of the collapsed body load model, and a high-speed camera is used for observing the falling movement characteristics of the collapsed body load model;
C. before the collapse body load model falls, the recording instruments of all the monitoring points are opened, the data of the initial monitoring points are recorded, the monitoring recording instruments are kept started, the whole process of the whole touchdown impact test is continuously monitored, and the monitoring process is ended until all the monitoring data are stable.
The invention has the beneficial effects that:
1. the test device and the method overcome the problem of difficult observation of the touchdown vibration effect in the actual engineering, simultaneously consider factors such as different touchdown modes, different forms of slump loads, different touchdown energies, different types of ground structures and the like, and realize the principle of realizing single variable control test in a multivariable system to a great extent;
2. through the test device measurement system, the comprehensive acquisition of dynamic response data such as dynamic strain, dynamic soil pressure, soil body acceleration, displacement and the like of the ground structure under the condition of touchdown impact of demolition blasting of collapsed bodies of the high-rise structure is realized, and theoretical basis and test support are provided for theoretical research and safety protection design of touchdown impact load of the collapsed bodies;
3. the device can simply and effectively simulate the quantitative observation of the touchdown impact and the load characteristic of the collapsed body demolition blasting of the high-rise structure, solves the problems that the test of the touchdown impact load characteristic of the collapsed body is difficult and the theoretical research of the load characteristic lacks actual measurement data and test support in the blasting demolition process of the high-rise structure, and provides theoretical basis and test support for the safety protection design of the blasting demolition safety and the protection object of the high-rise structure.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic view of a touchdown load model of the present invention;
FIG. 2 is a schematic diagram of the overall structure of the testing system of the present invention;
FIG. 3 is a schematic diagram of the soil layer structure in the model test box of the present invention (concrete panel-silty clay layer);
FIG. 4 is a schematic diagram of the soil structure (silty clay-gravelly soil) in the model test box of the invention.
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-soil pressure cell, 10-soil displacement meter, 11-strain gauge, 12-laser emitter, 13-photoelectric receiving device, 14-scale, 15-high speed camera and 16-foam.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Example 1:
with reference to fig. 1-4, in the embodiment of the present invention, an experimental apparatus for obtaining a touchdown impact load characteristic of a collapsed body is disassembled, the experimental apparatus includes a collapsed body load model 1, a model test box, a loading implementation apparatus and a monitoring measurement system, the model test box includes a test box 2, foam 16 is disposed on an outer side of the test box 2, and two layered ground structures of "hard top and soft bottom" and "soft top and hard bottom" are disposed in the test box 2; the loading test device is connected with the collapse body load model 1, the model test box is positioned below the loading test device, and the monitoring and measuring system is installed on the loading test device.
Referring to fig. 3, the collapsed body load model 1 has three contact modes with the soil body when contacting the ground: respectively planar contact, edge contact and cambered surface contact.
Referring to fig. 4, the layered floor structure with hard top and soft bottom 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 layered ground structure with soft upper part and hard lower part is as follows: a silty clay layer is arranged in the test box 2, and gravels are arranged on the lower side of the silty clay layer.
The loading test device comprises a small gantry crane 3, a fixed pulley 4 is mounted on the small gantry crane 3, a main cable 5 penetrates through the fixed pulley 4, one end of the main cable 5 is connected with a winch 6, the other end of the main cable 5 is connected with a connecting hook 7, and the connecting hook 7 is connected with the slump body load model 1.
The monitoring and measuring system comprises an accelerometer 8, a soil pressure gauge 9, a soil displacement gauge 10, a strain gauge 11, a dynamic signal acquisition instrument, a laser emitter 12, a photoelectric receiving device 13, a scale 14 and a high-speed camera 15, wherein three groups of measuring points are radially distributed on a test box 2 along a drop hammer point, each group of measuring points comprises dynamic strain test points on the surface of concrete, the strain gauge 11 is uniformly distributed on the dynamic strain test points, the soil pressure gauge 9, the displacement gauge 10 and the accelerometer 8 are uniformly distributed along the depth direction of the test box 2, two groups of laser emitters 12 and photoelectric receiving devices 13 are symmetrically arranged on the small gantry crane 3 and used for measuring the falling speed of the drop hammer, a computer for outputting the strain, the soil pressure, the acceleration, the displacement and the speed is arranged on one side of the test box 2, the scale 14 is arranged on one side of the test box 2, a high-speed camera 15 is arranged right in front of the test chamber 2.
Example 2:
an experiment method for obtaining an experiment device based on the characteristic of demolishing the touchdown impact load of a collapsed body comprises the following steps:
1) manufacturing of test box 2 and arrangement of monitoring measurement system: the test box 2 is internally provided with two layered ground structures of 'hard top and soft bottom' and 'soft top and hard bottom', the similar theory of model test and the actual operability of the test are considered at the same time, the similar scale of the basic physical quantity is obtained by calculation, a typical stratum model is selected, and a three-dimensional scale model similar to the two typical stratums is manufactured; three groups of measuring points are radially distributed on the test box 2 along the drop hammer point, each group of measuring points comprises dynamic strain test points on the surface of concrete, the strain gauges 11 are uniformly distributed on the dynamic strain test points, soil pressure gauges 9, displacement gauges 10 and accelerometers 8 are uniformly distributed in 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 scale 14 is arranged on one side of the test box 2, and a high-speed camera 15 is arranged right in front of the test box 2;
2) selecting a collapse body load model 1: in the blasting demolition engineering, the sizes of collapsed bodies are different and the shapes of the collapsed bodies are irregular when a high-rise structure collapses, so that the contact modes of the collapsed bodies with the soil body when the collapsed bodies touch the ground are also different greatly, and three contact modes of the collapsed bodies in the collapsed body load model 1 with the soil body when the collapsed bodies touch the ground are provided: respectively, plane contact, edge contact and cambered surface contact; meanwhile, the time difference existing when different collapse bodies touch the ground is considered, so that the ground-contact impact load forms with the same ground-contact mode and different ground-contact heights and the ground-contact load forms with different ground-contact heights and different contact modes are designed;
3) model loading application: after the test box 2 is installed, the collapse body load model 1 is lifted through a loading test device, the rising height of the collapse body load model 1 is measured through a scale 14, the collapse body load model 1 has different mass, and a plurality of collapse body load models 1 of the same type fall from different heights, so that the deformation and dynamic response characteristics of different stratum structures under the conditions of different impact energy, different ground contact modes and different collapse time intervals can be researched;
4) test testing and data recording: the method comprises the steps of selecting different collapse body load models 1, controlling the falling height of the load to carry out a ground contact impact test, and obtaining the damage forms and deformation characteristics of different ground structures under different ground contact load conditions and the moving soil response characteristic parameters of acceleration, moving soil pressure and moving stress.
The manufacturing of the test box 1 in the step 1) specifically comprises the following steps:
A. determining a similarity ratio
Carrying out parameter design according to a first similarity theory similarity criterion and a second similarity theory similarity criterion, determining that the geometric similarity ratio of the geometric dimension of a prototype and the geometric dimension of a device in actual engineering is L-10, and designing the ground dimension and the depth of the model according to the geometric similarity ratio and 1/10 of the prototype dimension; the gravity acceleration similarity ratio Cg is 1, the density similarity ratio Crho is 1, the volume-weight similarity ratio Cgamma is 1, the geometric similarity ratio and the volume-weight similarity ratio are taken as the basis similarity ratio, the Poisson ratio and the friction angle are completely similar, and the elastic modulus is designed according to the L of the elastic modulus of the prototype structural material; meanwhile, ensuring that the collapse load quality and the collapse load speed are similar according to the dimensional relationship, and determining the soil layer similarity ratio as follows:
geometric similarity ratio: cL＝L；
Volume-weight similarity ratio: c γ ═ 1;
pressure similarity ratio Cξ＝Cγ×CL；
Concentration force similarity ratio psi ═ Cγ×CL 3；
Stress similarity ratio Cσ＝L；
Displacement similarity ratio Cs ═ CL；
B. Test box for making model
Taking an actual prototype as reference, simultaneously according to a dynamic boundary effect and an elastic wave transmission speed, the model area is more than 5 times of the load main action area, considering that the longest side length of the load of a cuboid block and a triangular prism block is not less than 300mm, the radius of a large sphere is not less than 100mm, the size of a test platform is 1000mm multiplied by 1000mm, the length, the width and the height of a model test box model are 900mm, four sides around the test box 2 are made of steel plate materials, after the polishing treatment of mortar plastering, sponge with the thickness of 3cm is respectively pasted, according to a set geometric similarity ratio, the actual prototype is taken as reference, different stratum landfill positions are marked on the inner side of the steel plate of the test box 2, wherein a powder clay layer in a hard upper soft stratum and a hard lower soft stratum of a concrete panel-powder clay layer is positioned at the bottom of the test box 2 and has the thickness of 850mm, the concrete panel is positioned at the upper part of the powder clay layer and has the thickness of 50mm, marking the size of the test box A, and manufacturing a model test box according to the requirements; the crushed stone in the soft upper and hard lower strata of the silty clay layer-crushed stone layer is positioned at the bottom of the model test box and 500mm thick, the silty clay layer is positioned at the top of the test box 2 and 400mm thick, the size of the test box B is marked, and the model test box is manufactured according to the requirements;
C. making soil layer material
And calculating the weighted average gravity of the actual soil layer according to a weighted average algorithm, solving the physical parameters of the soil layer similar materials in the model test according to the determined similar proportion value, layering the soil layer similar materials into a prepared model test box for hammering and tamping, and presetting a collapse point.
The selection operation steps of the slump body load model 1 in the step 2) are as follows:
the load is summarized into three types of plane contact, edge contact and cambered surface contact according to the actual common contact mode of a collapsed body with a soil body when contacting the ground, namely cuboid blocks, triangular prism blocks and spherical blocks are adopted, the weight of each block is 9kg, 15kg and 21kg, and meanwhile, considering that the collapse body load is continuously impacted for multiple times when contacting the ground, three small cuboid blocks, three small triangular prism blocks and three small spherical blocks are also designed, each small block is 3kg, 5kg and 7kg, three small blocks of the same type are arranged and fall at different heights simultaneously, so that the effect of time difference when different collapsed loads contact the ground is achieved, and the height difference in the experiment is 10 cm; in order to simulate the energy influence caused by the falling height, the falling height is selected to be 0.5m, 1m and 1.5m, and the load lifting height is changed by using a scale 14;
during the test, a single variable control factor is considered, when the test is started, a certain collapsed body load model 1 is tested, other conditions are controlled to be unchanged, and the quality of the collapsed body load model 1 is changed;
secondly, controlling the mass of the collapsed body load model 1 to be unchanged, changing the falling height, and then controlling other quantities to be unchanged to change the model test box;
repeating the above steps of the slump body load model 1 of another form; meanwhile, considering that the collapse body load model 1 has the characteristic of multiple continuous impacts due to the contact impact, and a certain time difference exists due to the multiple contact impacts, the simultaneous falling test with the height difference of 10cm is carried out on the collapse body load models 1 in different forms;
in addition, considering the complexity of the collapse process of the actual blasting demolition engineering, a small cuboid model, a triangular prism model and a spherical model can be selected to fall to the ground simultaneously, so that the damage form and the dynamic response characteristic of the ground structure model under the corresponding collapse condition can be obtained.
The operation steps of applying the model loading in the step 3) are as follows:
A. placing the test box 2, and placing the test box 2 on a horizontal ground;
B. selecting a collapsed body load model 1 to be hung at a connecting hook 7 through a string, and lifting the collapsed body load model 1 to fixed heights of 0.5m, 1.0m and 1.5m by rotating a handle of a hand winch 6 to ensure that the surface of the collapsed body load model 1 is horizontal to the ground; opening a test instrument, adjusting the initial state of the test instrument, and preparing a test record;
C. the rope connecting the hook 7 and the slump body load model 1 is disconnected, so that the slump body load model 1 falls freely, the load height, the load mass, the load type, the load grounding type and the ground structure are changed in sequence in a single variable control mode, and the test is repeated.
The operation steps of the test and the data recording in the step 4) are as follows:
A. in the pouring process of the slump body load model 1, setting collapse points in advance, arranging three groups of measuring points along the radial direction of the collapse points, wherein the horizontal distances of the measuring points are 0.2m and 0.4m respectively, burying a group of accelerometers 8, a soil pressure gauge 9 and a soil displacement meter 10 every 0.2m from the top of the slump body load model 1 downwards, arranging representative measuring points at a soft and hard soil layer interface, arranging strain monitoring points, namely strain gauges 11, when the slump body load model 1 is poured in layers, bonding the strain monitoring points on the layered interface, and completing the whole monitoring point burying process in the pouring manufacturing stage of the slump body load model 1;
B. meanwhile, a soil displacement meter 10 is arranged on the surface of the collapsed body load model 1 and used for recording the displacement of the collapsed body, a laser emitter 12 and a photoelectric receiving device 13 are arranged around the device and used for measuring the movement speed of the collapsed body load model 1, and a high-speed camera 15 is used for observing the falling movement characteristics of the collapsed body load model 1;
C. before the collapse body load model 1 falls, the recording instruments of all monitoring points are opened, the data of the initial monitoring points are recorded, the monitoring recording instruments are kept started, the whole process of the whole touchdown impact test is continuously monitored until all the monitoring data are stable, and the monitoring process is finished.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (10)
1. The collapse body grounding impact load characteristic dismantling experimental device is characterized by comprising a collapse body load model (1), a model test box, a loading implementation device and a monitoring measurement system, wherein the model test box comprises a test box (2), foam (16) is arranged on the outer side of the test box (2), and two layered ground structures of 'hard top and soft bottom' and 'soft top and hard bottom' are arranged in the test box (2); the loading test device is connected with the collapse body load model (1), the model test box is positioned below the loading test device, and the monitoring measurement system is installed on the loading test device.
2. The experimental device for obtaining the touchdown impact load characteristics of demolished collapsed bodies according to claim 1, wherein the collapsed bodies in the collapsed body load model (1) are in contact with the soil body in three contact modes: respectively planar contact, edge contact and cambered surface contact.
3. The collapsed body grounding impact load feature removal experimental device as claimed in claim 1, wherein the layered ground structure with hard top and soft bottom is: a concrete panel is arranged in the test box (2), and a powdery clay layer is arranged on the lower side of the concrete panel; the layered ground structure with soft upper part and hard lower part is as follows: a silty clay layer is arranged in the test box (2), and gravels are arranged on the lower side of the silty clay layer.
4. The collapse body grounding impact load dismantling characteristic obtaining experimental device as claimed in claim 1, wherein the loading test device comprises a small gantry crane (3), a fixed pulley (4) is mounted on the small gantry crane (3), a main cable (5) penetrates through the fixed pulley (4), one end of the main cable (5) is connected with a winch (6), the other end of the main cable (5) is connected with a connecting hook (7), and the connecting hook (7) is connected with the collapse body load model (1).
5. The experimental device for obtaining the touchdown impact load characteristics of a demolished collapsed body according to claim 4, wherein the monitoring and measuring system comprises an accelerometer (8), a soil pressure gauge (9), a soil mass displacement meter (10), a strain gauge (11), a dynamic signal acquisition instrument, a laser emitter (12), a photoelectric receiving device (13), a scale (14) and a high-speed camera (15), three groups of measuring points are radially distributed on the test box (2) along a drop hammer point, each group of measuring points comprises a dynamic strain test point on the surface of concrete, the strain gauge (11) is uniformly distributed on the dynamic strain test point, the soil pressure gauge (9), the displacement meter (10) and the accelerometer (8) are uniformly distributed along the depth direction of the test box (2), two groups of laser emitters (12) and the photoelectric receiving device (13) are symmetrically arranged on the small gantry crane (3), a scale (14) is placed on one side of the test box (2), and a high-speed camera (15) is arranged right in front of the test box (2).
6. An experimental method for dismantling a collapsed body ground contact impact load characteristic obtaining experimental device based on the claim 5 is characterized by comprising the following steps of:
1) manufacturing a test box (2) and arranging a monitoring and measuring system: the test box (2) is internally provided with two layered ground structures of 'hard top and soft bottom' and 'soft top and hard bottom', the similar theory of model test and the actual operability of the test are considered at the same time, the similar scale of the basic physical quantity is obtained by calculation, a typical stratum model is selected, and a three-dimensional scale model similar to the two typical stratums is manufactured; three groups of measuring points are radially distributed on the test box (2) along a drop hammer point, each group of measuring points comprises dynamic strain test points on the surface of concrete, strain gauges (11) are uniformly distributed on the dynamic strain test points, soil pressure gauges (9), displacement gauges (10) and accelerometers (8) are uniformly distributed in 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 scale (14) is arranged on one side of the test box (2), and a high-speed camera (15) is arranged right in front of the test box (2);
2) selecting a collapsed body load model (1): in the blasting demolition engineering, when a high-rise structure collapses, collapsed bodies are different in size and irregular in shape, so that the contact modes of the collapsed bodies with the soil body when the collapsed bodies touch the ground are greatly different, and three contact modes of the collapsed bodies in the collapsed body load model (1) with the soil body when the collapsed bodies touch the ground are provided: respectively, plane contact, edge contact and cambered surface contact; meanwhile, the time difference existing when different collapse bodies touch the ground is considered, so that the ground-contact impact load forms with the same ground-contact mode and different ground-contact heights and the ground-contact load forms with different ground-contact heights and different contact modes are designed;
3) model loading application: after the test box (2) is installed, the collapse body load model (1) is lifted through a loading test device, and the lifting height of the collapse body load model (1) is measured through a ruler (14);
4) test testing and data recording: the method comprises the steps of selecting different collapse body load models (1), controlling the falling height of the load to carry out a ground contact impact test, and obtaining the damage forms and deformation characteristics of different ground structures under different ground contact load conditions and the moving soil response characteristic parameters of acceleration, moving soil pressure and moving stress.
7. The experimental method for dismantling the collapsed body ground contact impact load characteristic obtaining experimental facility as claimed in claim 6, wherein the manufacturing of the test box (1) in the step 1) specifically comprises the following steps:
A. determining a similarity ratio
Carrying out parameter design according to a first similarity theory similarity criterion and a second similarity theory similarity criterion, determining that the geometric similarity ratio of the geometric dimension of a prototype and the geometric dimension of a device in actual engineering is L-10, and designing the ground dimension and the depth of the model according to the geometric similarity ratio and 1/10 of the prototype dimension; the gravity acceleration similarity ratio Cg is 1, the density similarity ratio Crho is 1, the volume-weight similarity ratio Cgamma is 1, the geometric similarity ratio and the volume-weight similarity ratio are taken as the basis similarity ratio, the Poisson ratio and the friction angle are completely similar, and the elastic modulus is designed according to the L of the elastic modulus of the prototype structural material; meanwhile, ensuring that the collapse load quality and the collapse load speed are similar according to the dimensional relationship, and determining the soil layer similarity ratio as follows:
geometric similarity ratio: cL＝L；
Volume-weight similarity ratio: c γ ═ 1;
pressure similarity ratio Cξ＝Cγ×CL；
Concentration force similarity ratio psi ═ Cγ×CL 3；
Stress similarity ratio Cσ＝L；
Displacement similarity ratio Cs ═ CL；
B. Test box for making model
Taking an actual prototype as reference, simultaneously according to a dynamic boundary effect and an elastic wave transmission speed, the model area is more than 5 times of the main action area of the load, considering that the longest side length of the load of a cuboid block and a triangular prism block is not less than 300mm, the radius of a large sphere is not less than 100mm, the size of a test platform is 1000mm multiplied by 1000mm, the length, the width and the height of a model test box model are 900mm, four sides around a test box (2) are made of steel plate materials, after mortar plastering and polishing treatment are adopted, sponges with the thickness of 3cm are respectively pasted, according to a set geometric similarity ratio, the actual prototype is taken as reference, different stratum landfill positions are marked on the inner side of the steel plate of the test box (2), wherein a powdery clay layer in a hard upper soft stratum of a concrete panel-powdery clay layer is positioned at the bottom of the test box (2), the thickness is 850mm, the concrete panel is positioned at the upper part of the powdery clay layer, marking the thickness of the test box A to be 50mm, and manufacturing a model test box according to the requirements; the method comprises the following steps that (1) gravels in a soft upper hard stratum and a hard lower hard stratum of the silty clay layer-gravels are located at the bottom of a model test box and 500mm in thickness, the silty clay layer is located at the top of the test box (2) and 400mm in thickness, the size of the silty clay layer is marked in a test box B, and the model test box is manufactured according to the requirements;
C. making soil layer material
And calculating the weighted average gravity of the actual soil layer according to a weighted average algorithm, solving the physical parameters of the soil layer similar materials in the model test according to the determined similar proportion value, layering the soil layer similar materials into a prepared model test box for hammering and tamping, and presetting a collapse point.
8. The experimental method for dismantling the touchdown impact load characteristic acquisition experimental facility of the collapsed body according to claim 6, wherein the selecting operation steps of the collapsed body load model (1) in the step 2) are as follows:
the load is summarized into three types of plane contact, edge contact and cambered surface contact according to the actual common contact mode of a collapsed body and a soil body when the collapsed body contacts the ground, namely cuboid blocks, triangular prism blocks and spherical blocks are adopted, the weight of each block is 9kg, 15kg and 21kg, meanwhile, considering that the collapse body load contacts the ground to be multiple continuous impact, three small cuboid blocks, three small triangular prism blocks and three small spherical blocks are also designed, each small block respectively has 3kg, 5kg and 7kg, three small blocks of the same type are arranged, and the three small blocks are located at different heights and fall simultaneously;
during the test, a single variable control factor is considered, when the test is started, the test of a certain collapsed body load model (1) is firstly carried out, other conditions are controlled to be unchanged, and the quality of the collapsed body load model (1) is changed;
secondly, controlling the mass of the collapsed body load model (1) to be unchanged, changing the falling height, and then controlling other quantities to be unchanged to change the model test box;
repeating the above steps of the collapse body load model (1) of another form; meanwhile, considering that the collapse body load model (1) has the characteristic of multiple continuous impacts due to the contact impact, and a certain time difference exists due to the multiple contact impacts, the simultaneous falling test with the height difference of 10cm is carried out on the collapse body load models (1) in different forms;
in addition, considering the complexity of the collapse process of the actual blasting demolition engineering, a small cuboid model, a triangular prism model and a spherical model can be selected to fall to the ground simultaneously, so that the damage form and the dynamic response characteristic of the ground structure model under the corresponding collapse condition can be obtained.
9. The experimental method for dismantling the collapsed body ground contact impact load characteristic obtaining experimental device as claimed in claim 6, wherein the operation steps of applying model loading in the step 3) are as follows:
A. placing the test box (2), and placing the test box (2) on a horizontal ground;
B. selecting a collapsed body load model (1) to be hung at a connecting hook (7) through a string, and lifting the collapsed body load model (1) to the positions with fixed heights of 0.5m, 1.0m and 1.5m by rotating a handle of a hand winch (6) to ensure that the surface of the collapsed body load model (1) is horizontal to the ground; opening a test instrument, adjusting the initial state of the test instrument, and preparing a test record;
C. and disconnecting the connecting hook (7) and the string of the collapse body load model (1) to enable the collapse body load model (1) to freely fall, sequentially changing the load height, the load mass, the load type, the load grounding type and the ground structure in a single variable control mode, and repeating the test.
10. The experimental method for dismantling the collapsed body ground contact impact load characteristic obtaining experimental device as claimed in claim 6, wherein the operation steps of the test and the data recording in the step 4) are as follows:
A. in the pouring process of the collapse body load model (1), setting collapse points in advance, arranging three groups of measuring points along the radial direction of the collapse points, wherein the horizontal distances of the measuring points are 0.2m and 0.4m respectively, burying a group of accelerometer (8), a soil pressure gauge (9) and a soil displacement meter (10) from the top of the collapse body load model (1) downwards every 0.2m or so, laying representative measuring points at a soft and hard soil layer interface, and adhering strain monitoring points, namely strain gauges (11) to a layered interface when the collapse body load model (1) is poured in layers, wherein the whole monitoring point burying process is completed in the pouring and manufacturing stage of the collapse body load model (1);
B. meanwhile, a soil displacement meter (10) is arranged on the surface of the collapsed body load model (1) and used for recording the displacement of the collapsed body, a laser transmitter (12) and a photoelectric receiving device (13) are arranged around the device and used for measuring the movement speed of the collapsed body load model (1), and a high-speed camera (15) is used for observing the falling movement characteristics of the collapsed body load model (1);
C. before the collapse body load model (1) falls, the recording instruments of all monitoring points are opened, data of the initial monitoring points are recorded, the monitoring recording instruments are kept started, the whole process of the whole touchdown impact test is continuously monitored until all the monitoring data are stable, and the monitoring process is finished.
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| CN116735387A (en) * | 2023-08-08 | 2023-09-12 | 河海大学 | Device and method for testing impulse power response of grotto under complex conditions |
| CN116735387B (en) * | 2023-08-08 | 2023-11-14 | 河海大学 | Device and method for testing impulse power response of grotto under complex conditions |
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