A continuous dynamic monitoring device for gravel soil vibration compaction process and its use method

Abstract

The present invention relates to the field of engineering tests, and in particular, designs a device for continuous dynamic monitoring of the indoor vibration compaction process of gravel soil and a method for using the device. The device includes a guide frame, an acceleration sensor, a vibration compactor drop hammer, and a microcomputer automatic data acquisition instrument. The present invention combines the vibration compactor used in the indoor heavy compaction test to establish a continuous dynamic monitoring system for the indoor vibration compaction process of gravel soil, studies the compaction law of gravel soil based on the indoor heavy compaction test under different frequencies and times of the vibration compactor calibration, and implements continuous dynamic monitoring of the vibration compaction process of soil-rock mixed materials, which is helpful to monitor the changes in the compaction state of gravel soil and understand the entire process of the formation of the structure of the roadbed filling layer. It is of great significance for studying the compaction quality control and is conducive to reducing the on-site engineering volume and accelerating the construction progress.

Description

Technical Field

[0001] The invention relates to the field of engineering experiments, and in particular to a device for continuously dynamically monitoring a gravel soil indoor vibration compaction process and a method for using the device. Background Art

[0002] The characteristics of crushed stone soil material are relatively complex. It is a mixed material composed of crushed stone particles of various particle sizes and soil particles. It can be used for high-grade asphalt pavement flexible base structure and railway roadbed subgrade structure. A key factor in forming an excellent structure is to monitor the quality during the structure formation process. The general indicator for evaluating the degree of compaction of materials is expressed by compaction density, but it has two shortcomings. One is that it cannot be measured during the compaction process of the material; the other is that when the crushed stone particles are large enough, it is much more difficult to conduct density tests indoors, and it is not easy to measure accurately. Therefore, it is particularly important to find other indicators that express the changes in the compaction state of materials. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a continuous dynamic monitoring device for the indoor vibration compaction process of gravel soil and a method of using the same. By real-time and continuous monitoring of the dynamic response signal of the compaction machine, relevant information on changes in the compaction state of the material is obtained, which plays a role in rapid quality monitoring and can effectively improve the quality of the project.

[0004] A continuous dynamic monitoring device for indoor vibration compaction process of crushed stone soil, comprising a guide frame, an acceleration sensor, a vibration compaction instrument drop weight and a microcomputer automatic data acquisition instrument;

[0005] The guide frame includes a tripod and three support columns, the three support columns support the tripod to be horizontally arranged, the three support columns are respectively located at the bottom of the corners of the tripod and are fixed to the tripod by bolts;

[0006] The vibratory compactor drop hammer is installed at the center of the guide frame and connected to the support column through three connecting rods, one end of each connecting rod is connected to the vibratory compactor drop hammer, and the other end is connected to a support column;

[0007] The acceleration sensor is installed on one of the connecting rods and is connected to a microcomputer automatic data acquisition instrument through a wire.

[0008] Preferably, the drop hammer of the vibratory compactor includes a hammer handle, a hammer body is arranged at the bottom of the hammer handle, a built-in clamping block is installed in the middle and lower part of the hammer handle, the built-in clamping block is composed of two menisci with a serrated portion at the bottom to form a cylinder, wrapped around the outside of the hammer handle, the thickness of each serrated portion gradually becomes thinner to the end, and the built-in clamping block is fixed by an external clamping block.

[0009] Preferably, an external card block is installed outside the built-in card block, and the external card block includes two menisci with fixing parts set at both ends, the fixing parts are straight, and the fixing parts of the two menisci can be matched together in pairs, and each fixing part is provided with screw holes of the same size, equal number and relative position, and the screw holes on the two menisci can be connected by the card block bolts, so that the external card block is fixed to the middle and lower end of the built-in card block and wraps the serrated part.

[0010] Preferably, one end of each of the connecting rods is evenly spaced and fixed on the outside of the built-in block at the same horizontal height, and a guide sliding bearing is installed on the end of each of the connecting rods connected to the support column. Each guide sliding bearing is adapted to the outer diameter of the support column, is sleeved on each support column and can slide vertically along the support column.

[0011] Preferably, a magnetic sheet is provided at the bottom of the acceleration sensor, which is adsorbed on one of the connecting rods through the magnetic sheet. A fixed block is connected to the outside of the acceleration sensor, and the fixed block is connected to the acceleration sensor and the connecting rod through bolts.

[0012] Preferably, a base is installed at the bottom of each support column, and a rubber pad is pasted on the bottom of the base, and the thickness of the rubber pad is preferably 0.5 cm.

[0013] Preferably, the tripod is an equilateral triangle, and three support columns are vertically installed directly below the three corners of the tripod.

[0014] A method for continuous dynamic monitoring of a crushed stone soil vibration compaction process, using the above-mentioned device for continuous dynamic monitoring of a crushed stone soil indoor vibration compaction process, specifically comprising the following steps:

[0015] a. Assemble the guide frame, place the support column at a suitable position outside the vibratory compactor drop hammer, splice the built-in block to the periphery of the hammer handle of the vibratory compactor drop hammer, and insert the guide sliding bearings at one end of each connecting rod into the outside of a support column respectively. Put the tripod on the top of the support column and tighten the bolts, splice the external block to the middle and lower part of the outside of the built-in block and tighten the block bolts to fix the built-in block;

[0016] b. Fix the acceleration sensor on one of the connecting rods, and connect the acceleration sensor to the microcomputer automatic data acquisition instrument through a wire;

[0017] c. Place the test barrel filler at the bottom of the vibration compactor drop hammer 4, lower the vibration compactor drop hammer to the specified position, adjust the vibration compactor frequency and time, start the microcomputer automatic data acquisition instrument and the vibration compactor to collect data, analyze the compaction process, and understand the changes in the structural compaction state by analyzing the changes in the acceleration response of the compaction tool. The specific sub-steps are as follows;

[0018] c1. The acceleration signal a in the vertical direction is collected in real time by using a vibration acceleration sensor installed on the indoor vibration compactor. The sampling time interval t is small enough to meet the indoor compaction accuracy requirements. In the calculation and analysis submodule of the microcomputer automatic data acquisition instrument, the real-time collected drop weight vibration acceleration signal is filtered to obtain the time domain curve at of the acceleration changing with time.

[0019] c2. Perform Fourier transform on the time domain curve at, establish a quality detection, evaluation and feedback system for indoor vibration compaction of crushed stone soil, realize real-time detection and control of indoor compaction quality of crushed stone soil, and calculate the vibration compaction value ICV. ICV is the ratio of the peak-to-peak value of the acceleration time domain curve to the amplitude of the fundamental frequency signal. The calculation formula is:

[0020]

[0021] Where: K is a constant coefficient with a value of 0.2, F A-B is the peak-to-peak value of the vibration acceleration time domain curve; N0 is the amplitude of the fundamental frequency signal;

[0022] The smaller the ICV value, the less compacted the gravel soil is. As the compaction process progresses, the gravel soil becomes more and more compact. A-B The ratio of the peak-to-peak value to the fundamental frequency amplitude will become larger, that is, the ICV value will increase. The change in the ICV value reflects the degree of compaction of the gravel soil by indoor vibration compaction.

[0023] Compared with the prior art, the present invention is beneficial in that:

[0024] (1) The present invention combines the vibration compactor used in the indoor heavy compaction test to establish a continuous dynamic monitoring system for the indoor vibration compaction process of gravel soil. The compaction law of gravel soil based on the indoor heavy compaction test under the conditions of different frequencies and times calibrated by the vibration compactor is studied. The vibration compaction process of soil-rock mixed materials is continuously and dynamically monitored, which is helpful to monitor the changes in the compaction state of gravel soil and understand the entire process of the formation of the structure of the roadbed filling layer. It is of great significance for studying the compaction quality control.

[0025] (2) The change in resistance of the soil-rock mixture during the compaction process is used to monitor the change in compaction state. Under the same vibration compaction process, the change in acceleration information can be used for monitoring and evaluation, making the test work more convenient.

[0026] (3) When evaluating the compaction state of coarse-grained materials, the change in the vibration compaction value reflected by the change in the acceleration signal can be used to express the change in the compaction state. This can replace the existing evaluation index - compaction degree, and has important practical significance. It provides a basis for continuous quality monitoring of the compaction of coarse-grained materials on site.

[0027] (4) When used in conjunction with an indoor vibration compactor, the quality monitoring of the vibration compaction process of gravel soil can be completed indoors, which is of great significance for determining the compaction process before construction and is conducive to reducing on-site engineering workload and accelerating construction progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a front view of a device for continuously dynamically monitoring the indoor vibration compaction process of gravel soil according to the present invention;

[0029] Figure 2 This is a schematic diagram of the card block structure of the present invention;

[0030] Figure 3 It is an enlarged schematic diagram of the acceleration sensor structure of the present invention;

[0031] Figure 4 It is a curve obtained by Fourier transformation of the time domain curve of the present invention;

[0032] Figure 5 It is the vibration compaction value curve of the present invention that changes with time.

[0033] In the figure: 1. support column, 2. tripod, 3. bolt, 4. vibration compactor drop weight, 5. rubber pad, 6. base, 7. guide sliding bearing, 8. connecting rod, 9. acceleration sensor, 10. magnetic sheet, 11. fixed card block, 12. card block bolt, 13. external card block, 14. internal card block, 15. wire, 16. microcomputer automatic data acquisition instrument, 1301. fixing part, 1302. screw hole, 1401. serrated part. DETAILED DESCRIPTION

[0034] The drawings are for illustrative purposes only; in order to better illustrate the present embodiment, some parts of the drawings are omitted, enlarged or reduced, and do not represent the size of the actual product; the terms "upper", "lower", "left", "right", "side", "outer", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. For those skilled in the art, some well-known structures in the drawings and their descriptions may be omitted, and therefore cannot be understood as a limitation on the present invention.

[0035] In order to make the technical means, creative features, purpose and efficacy of the present invention easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0036] like Figure 1 As shown, a device for continuous dynamic monitoring of indoor vibration compaction process of crushed stone soil includes a guide frame, an acceleration sensor 9, a vibration compactor drop hammer 4 and a microcomputer automatic data acquisition device 16;

[0037] The guide frame includes a tripod 2 and a support column 1. Three identical support columns 1 are arranged and installed at the bottom of the tripod 2. The three support columns 1 are used to support the tripod 2 to be arranged horizontally. The tripod 2 is an equilateral triangle. Each support column 1 is located at the bottom of the corner of the tripod 2 and is fixed by a bolt 3 and a matching screw hole.

[0038] The vibratory compactor drop hammer 4 is installed at the center of the guide frame and connected to the support column 1 through three connecting rods 8. One end of each connecting rod 8 is connected to the vibratory compactor drop hammer 4, and the other end is connected to a support column 1. The vibratory compactor drop hammer 4 includes a hammer handle, and a hammer body is arranged at the bottom of the hammer handle. The hammer handle is an elongated cylinder, and the hammer body is a cylinder whose upper end face is larger than the bottom end face of the hammer handle, but the height is smaller than the hammer handle. A built-in clamping block 14 is installed in the middle and lower part of the hammer handle. The built-in clamping block 14 is composed of two menisci with a serrated portion 1401 at the bottom to form a cylinder, which is wrapped around the outside of the hammer handle. The thickness of the outer side of each serrated portion 1401 gradually becomes thinner, and the thickness is the thinnest at the end (i.e., the bottom end), but the inner diameter of the serrated portion 1401 is the same as the inner diameter of the middle and upper part of the built-in clamping block 14. This design is for better fixation.

[0039] A base 6 is installed at the bottom of each support column 1, and a rubber pad 5 is pasted on the bottom of the base 6. The thickness of the rubber pad 5 is 0.5 cm.

[0040] like Figure 1 , Figure 2 As shown, the external card block 13 is installed outside the internal card block 14, and the internal card block 14 is fixed by the external card block 13, and the inner diameter of the external card block 13 is adapted to the outer diameter of the internal card block 14. The external card block 13 includes two menisci with fixing parts 1301 at both ends, and the fixing parts 1301 are straight. The fixing parts 1301 of the two menisci can be matched together in pairs, and each fixing part 1301 is provided with screw holes 1302 of the same size, equal number and relative position. The screw holes on the two menisci can be connected by the card block bolt 12, so that the external card block 13 is fixed to the middle and lower end of the internal card block 14 and wraps the serrated part 1401. Since the serrated part 1401 at the bottom of the internal card block 14 gradually becomes thinner to the end, the external card block 13 can only be wrapped on the outside by the bolt, and the internal card block 14 will not slide.

[0041] As a further preferred design, a rubber gasket may be provided at the wrapping position, and the fixing portion 1301 of the external clamping block 13 may be tightened or loosened by bolts and nuts for proper adjustment.

[0042] One end of each connecting rod 8 is fixed to the outside of the built-in block 14, and each connection point is evenly spaced and at the same level. A guide sliding bearing 7 is installed at one end of each connecting rod 8 connected to the support column 1. Each guide sliding bearing 7 is adapted to the outer diameter of the support column 1, is sleeved on each support column 1, and can slide vertically along the support column 1.

[0043] like Figure 1 , Figure 3 As shown, the acceleration sensor 9 is installed on one of the connecting rods 8 and is connected to a microcomputer automatic data acquisition device 16 via a wire 15 .

[0044] A magnetic sheet is arranged at the bottom of the acceleration sensor 9, which is adsorbed on one of the connecting rods 8 through a magnetic sheet 10. A fixed block 11 is connected to the outside of the acceleration sensor 9, and the fixed block 11 connects the acceleration sensor 9 and the connecting rod 8 through bolts.

[0045] About the application examples of the present invention:

[0046] The present invention uses an indoor vibrating compactor to conduct an in-depth study on the vibrating compaction process of crushed stone soil materials. The interaction relationship between the compactor and the compressed material is analyzed, and the structure formed by the crushed stone soil and the vibration equipment of the vibrating compactor on the working material are regarded as two subsystems. By utilizing the principle of system identification and continuously monitoring the dynamic response of the compactor during the crushed stone soil forming process, the response information related to the acceleration change is obtained, and the change in the compaction state is judged by the degree of change of the acceleration signal, so that the indoor compaction process of the crushed stone soil is continuously monitored in real time. This technology also ensures the construction quality on site. Practice has proved that under certain conditions, the dynamic response signal of the compactor can be continuously monitored in real time to obtain relevant information on the change in the compaction state of the material, which plays a role in rapid quality monitoring and can effectively improve the quality of the project.

[0047] A method for continuous dynamic monitoring of a crushed stone soil vibration compaction process, using the above-mentioned device for continuous dynamic monitoring of a crushed stone soil indoor vibration compaction process, specifically comprising the following steps:

[0048] a. Assemble the guide frame, place the support column 1 at a suitable position outside the vibration compactor drop hammer 4, splice the built-in block 14 to the periphery of the hammer handle of the vibration compactor drop hammer 4, and insert the guide sliding bearing 7 at one end of each connecting rod 8 into the outside of a support column 1 respectively. Put the tripod 2 on the top of the support column 1 and tighten the bolt 3, splice the external block 13 to the middle and lower part of the outside of the built-in block 14 and tighten the block bolt 12 to fix the built-in block 14;

[0049] b. The acceleration sensor 9 is fixed to one of the connecting rods 8, and the acceleration sensor 9 is connected to the microcomputer automatic data acquisition device 16 through a wire;

[0050] c. Place the test barrel filler at the bottom of the vibrating compactor drop hammer 4, lower the vibrating compactor drop hammer 4 to the specified position, adjust the frequency and time of the vibrating compactor, the frequency is 500Hz, start the microcomputer automatic data acquisition instrument and the vibrating compactor to collect data, analyze the compaction process, the specific sub-steps are;

[0051] c1. The acceleration signal a in the vertical direction is collected in real time by using a vibration acceleration sensor installed on the indoor vibration compactor. The sampling time interval t is small enough to meet the indoor compaction accuracy requirements. In the calculation and analysis submodule of the microcomputer automatic data acquisition instrument, the real-time collected drop weight vibration acceleration signal is filtered to obtain the time domain curve at of the acceleration changing with time.

[0052] like Figure 4 As shown, c2. Perform Fourier transform on the time domain curve at to obtain the transformed vibration acceleration signal spectrum, where f is the amplitude of the spectrum and has no unit. Establish a quality detection, evaluation and feedback system for indoor vibration compaction of crushed stone soil to achieve real-time detection and control of indoor compaction quality of crushed stone soil and calculate the vibration compaction value ICV.

[0053] During the indoor vibration compaction process, the ICV value was extracted and observed every 3 seconds. The following Table 1 shows the measurement data.

[0054] Table 1 shows the fundamental frequency signal amplitude, acceleration time domain curve peak-to-peak value and vibration compaction value recorded every 3 seconds

[0055]

[0056] like Figure 5 As shown in the figure, the calculated vibration compaction value ICV. The smaller the ICV value, the less compacted the gravel soil is. As the compaction process progresses, the gravel soil becomes more and more compact, and the ratio of the peak-to-peak value to the fundamental frequency amplitude becomes larger, that is, the ICV value increases. The change in the ICV value reflects the compactness of the indoor vibration compaction of the gravel soil.

[0057] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Other matters not mentioned adopt the common practices in the prior art and will not be described in detail here.

[0059] 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. A method for continuous dynamic monitoring of indoor vibration compaction process of crushed stone soil, using a device for continuous dynamic monitoring of indoor vibration compaction process of crushed stone soil, characterized in that: It includes a guide frame, an acceleration sensor, a vibratory compactor drop weight and a microcomputer automatic data acquisition instrument; The vibratory compactor drop hammer comprises a hammer handle, a hammer body is arranged at the bottom of the hammer handle, a built-in clamping block is installed at the middle and lower part of the hammer handle, the built-in clamping block is composed of two menisci with a serrated portion at the bottom to form a cylinder, wrapped around the outside of the hammer handle, the thickness of each serrated portion gradually becomes thinner to the end, and the built-in clamping block is fixed by an external clamping block; The guide frame includes a tripod and three support columns, the three support columns support the tripod to be horizontally arranged, the three support columns are respectively located at the bottom of the corners of the tripod and are fixed to the tripod by bolts; The vibratory compactor drop hammer is installed at the center of the guide frame and is connected to the support column through three connecting rods, one end of each connecting rod is connected to the vibratory compactor drop hammer, and the other end is connected to a support column; The acceleration sensor is installed on one of the connecting rods and connected to a microcomputer automatic data acquisition instrument through a wire; The specific steps of the monitoring method are: a. Assemble the guide frame, place the support column at a suitable position outside the vibratory compactor drop hammer, splice the built-in block to the periphery of the hammer handle of the vibratory compactor drop hammer, and insert the guide sliding bearings at one end of each connecting rod into the outside of a support column respectively. Put the tripod on the top of the support column and tighten the bolts, splice the external block to the middle and lower part of the outside of the built-in block and tighten the block bolts to fix the built-in block; b. Fix the acceleration sensor on one of the connecting rods, and connect the acceleration sensor to the microcomputer automatic data acquisition instrument through a wire; c. Place the test barrel filler at the bottom of the vibrating compactor drop hammer, lower the vibrating compactor drop hammer to the specified position, adjust the frequency and time of the vibrating compactor, start the microcomputer automatic data acquisition instrument and the vibrating compactor to collect data, analyze the compaction process, and understand the changes in the structural compaction state by analyzing the changes in the acceleration response of the compaction tool. The specific sub-steps are as follows; c1. The acceleration signal a in the vertical direction is collected in real time by using a vibration acceleration sensor installed on the indoor vibration compactor. The sampling time interval t is small enough to meet the indoor compaction accuracy requirements. In the calculation and analysis submodule of the microcomputer automatic data acquisition instrument, the real-time collected drop weight vibration acceleration signal is filtered to obtain the time domain curve at of the acceleration changing with time. c2. Perform Fourier transform on the time domain curve at, establish a quality detection, evaluation and feedback system for indoor vibration compaction of crushed stone soil, realize real-time detection and control of indoor compaction quality of crushed stone soil, and calculate the vibration compaction value ICV, which is the ratio of the peak-to-peak value of the acceleration time domain curve to the amplitude of the fundamental frequency signal; Where: K is a constant coefficient with a value of 0.2, F A-B is the peak-to-peak value of the vibration acceleration time domain curve; N0 is the amplitude of the fundamental frequency signal; The smaller the ICV value, the less compacted the gravel soil is. As the compaction process progresses, the gravel soil becomes more and more compact. A-B The ratio of the peak-to-peak value to the fundamental frequency amplitude will become larger, that is, the vibration compaction value ICV value will increase. The change in the ICV value is used to reflect the degree of compaction of the gravel soil by indoor vibration compaction.

2. The method for continuous dynamic monitoring of indoor vibration compaction process of gravel soil according to claim 1 is characterized in that: An external card block is installed outside the internal card block, and the external card block includes two menisci with fixing parts at both ends, and each fixing part is provided with screw holes of the same size, equal number and relative position. The screw holes on the two menisci are connected by card block bolts, so that the external card block is fixed to the middle and lower end of the internal card block and wraps the serrated part.

3. The method for continuous dynamic monitoring of indoor vibration compaction process of gravel soil according to claim 1, characterized in that: One end of each connecting rod is evenly spaced and fixed on the outside of the built-in block and at the same horizontal height. A guide sliding bearing is installed at one end of each connecting rod connected to the support column. Each guide sliding bearing is adapted to the outer diameter of the support column, is sleeved on each support column and can slide vertically along the support column.

4. The method for continuous dynamic monitoring of indoor vibration compaction process of gravel soil according to claim 1, characterized in that: A magnetic sheet is arranged at the bottom of the acceleration sensor, and is adsorbed on one of the connecting rods through the magnetic sheet. A fixed block is connected to the outside of the acceleration sensor, and the fixed block is connected to the acceleration sensor and the connecting rod through bolts.

5. The method for continuous dynamic monitoring of indoor vibration compaction process of gravel soil according to claim 1, characterized in that: A base is installed at the bottom of each support column, and a rubber pad is pasted on the bottom of the base.

6. The method for continuous dynamic monitoring of indoor vibration compaction process of gravel soil according to claim 1, characterized in that: The tripod is an equilateral triangle, and three supporting columns are vertically installed just below the three corners of the tripod.

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