A test device and method for early-age concrete subjected to disturbance effects
By designing a test device including a geotechnical medium simulation block and a vibration transmission layer, the real load characteristics of early-age concrete being subjected to explosion impact are simulated, and the problem of disturbances in the early-age concrete being subjected to early-age concrete being subjected to is solved in the prior art. Research on the superposition of multiple shock sources is realized and research costs are reduced.
Patent Information
- Application Number
- CN202210203477.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-02
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2042-03-02
AI Technical Summary
The existing test devices cannot effectively simulate the real load characteristics of early-age concrete being affected by explosion impacts, and are costly and can only study the impact of a single impact source, and cannot reflect the superposition effect of multiple impact sources.
A test device including a geotechnical medium simulation block, a vibration transmission layer and a vibration consumption layer was designed. The explosion impact was simulated through the air pipe and the vibration membrane, and combined with an ultrasonic detection mechanism, the superposition influence of multiple shock sources can be simulated and reduced. Research costs.
Accurate simulation of the disturbances of early-age concrete is achieved, which reduces research costs, provides more accurate experimental results, avoids vibration back-transmission phenomenon, and supports the impact research of multiple shock sources.
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Figure CN114740085B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of civil engineering tests, and in particular to a test device and method for early-age concrete subjected to disturbance influence. Background Art
[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.
[0003] At present, with the increasing requirements for construction speed and the increasing distance between sites in the field of civil engineering, concrete is often disturbed by various external vibrations such as blasting, strong tamping, and vehicle vibration during the curing period. A large number of studies have shown that the strength of early-age concrete is relatively low and it is sensitive to external disturbances. Its internal colloids and crystals are still in the process of rapid development. Early disturbances have a huge impact on its later performance, especially for concrete support structures that are synchronized or interspersed with blasting operations. They are very close to the blasting source. Blasting construction will inevitably cause cumulative damage in early-age concrete structures, thereby affecting the long-term strength of the support structure. Therefore, it is very necessary to study the strength loss caused by early-age concrete after being disturbed. The existing test device usually uses a vibration table to apply a triangular load or conducts research through a Hopkinson pressure bar device. The inventor found that simplifying the impact into a triangular load that increases or decreases linearly according to the set value is significantly different from the actual load action form, and at the same time, it cannot reflect the superposition and interference characteristics of the explosion impact. Therefore, the load properties are not completely consistent with the explosion impact. The latter equipment is more complex and expensive and can only study the impact of a single impact source. Summary of the invention
[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a test device for the disturbance influence on early-age concrete, the load properties of which are consistent with the explosion impact, and the production cost is low, and the superposition influence of multiple impact sources can be studied.
[0005] To achieve the above object, the present invention adopts the following technical solution:
[0006] In a first aspect, an embodiment of the present invention provides a test device for early-age concrete subjected to disturbance, comprising a rock-soil medium simulation block, a sample placement cavity is provided inside the rock-soil medium simulation block, a vibration transmission layer is wrapped around the outer circumference of the rock-soil medium simulation block, and a vibration consumption layer is wrapped around the outer circumference of the vibration transmission layer;
[0007] It also includes at least one vibration generating mechanism, which includes an air pipe, one end of which is connected to an air source, and the other end of which serves as an end in contact with the vibration transmission layer and is provided with a vibration membrane.
[0008] Optionally, a detection mechanism is also included, which includes an ultrasonic transducer fixed at one end of the sample block and an ultrasonic probe fixed at the other end of the sample block, and the ultrasonic transducer is connected to the ultrasonic generator.
[0009] Optionally, the ultrasonic probe and the ultrasonic transducer are wrapped with a rubber vibration-damping layer.
[0010] Optionally, the vibration transmission layer includes a vibration adjustment medium layer on the outer peripheral surface of the rock and soil medium simulation block and a vibration transmission medium layer on the outer peripheral surface of the vibration adjustment medium layer.
[0011] Optionally, the vibration consumption layer includes a flexible material layer wrapped around the vibration transmission layer and a loose sand layer included around the flexible material layer.
[0012] Optionally, the flexible material layer is a rubber layer.
[0013] Optionally, the air pipe is a conical tube, the end with a larger area is fixed with a vibrating membrane, and the end with a smaller area is connected to the air source.
[0014] Optionally, a valve is provided in the trachea.
[0015] Optionally, a protective sleeve is provided on the outer periphery of the air pipe, the protective sleeve is fixedly connected to the air pipe, and the bottom end of the protective sleeve is flush with the end of the air pipe where the vibration membrane is installed.
[0016] In the second aspect, an embodiment of the present invention provides a working method of a test device for early-age concrete subjected to disturbance, wherein a sample block is placed in a sample placement cavity of a rock and soil medium simulation block, at least one vibration generating mechanism is placed at a set position on the upper end surface of a vibration transmission layer, and a vibration membrane is in contact with the upper end surface of the vibration transmission layer, and an air source passes a set pressure gas into an air pipe within a set time interval to simulate an explosion impact, thereby generating a vibration impact on the vibration transmission layer, which transmits the vibration and applies the vibration impact to the sample block through the soil medium simulation layer, and multiple vibration impacts are applied to the sample block until the experimental requirements are met and the sample block is taken out.
[0017] The beneficial effects of the present invention are as follows:
[0018] 1. In the test device of the present invention, a vibration membrane is provided at one end of the air pipe of the vibration generating mechanism, and the other end is connected to the air source. The gas generated by the air source can be used to impact the vibration membrane, thereby using the vibration membrane to generate a vibration impact on the vibration transfer layer, simulating the explosion impact vibration of concrete. Compared with the traditional triangular load, the vibration impact generated by the gas is more consistent with the explosion impact, and the test result is more accurate.
[0019] 2. The test device of the present invention is provided with at least one vibration generating mechanism, and a plurality of vibration generating mechanisms can be placed at set positions of the vibration transmission layer according to actual needs, so that the influence of a plurality of vibration impact sources on the sample can be realized simply and efficiently, thereby reducing the cost of scientific research and promoting the technological development in related fields.
[0020] 3. In the test device of the present invention, a protective tube is provided on the outer periphery of the air pipe, which plays a role of weighting and prevents the conical air pipe from being separated from the medium transfer layer under the action of gas.
[0021] 4. The test device of the present invention has a vibration consumption layer, and the radiated vibration energy can be absorbed and dissipated under the action of the vibration consumption layer, thereby avoiding the phenomenon of vibration feedback at the boundary. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The drawings in the specification, which constitute a part of the present application, are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute a limitation on the present application.
[0023] Figure 1 It is a schematic diagram of the overall structure of Embodiment 1 of the present invention;
[0024] Figure 2 is a top view of the overall structure of Example 1 of the present invention;
[0025] Figure 3 is a schematic structural diagram of a vibration generating mechanism according to Embodiment 1 of the present invention;
[0026] Among them, 1. concrete specimen block, 2. rock and soil medium simulation block, 3. vibration transmission medium layer, 4. vibration adjustment medium layer, 5. vibration generating mechanism, 5-1. air pipe, 5-2. metal membrane, 5-3. electric control valve. DETAILED DESCRIPTION
[0027] Example 1
[0028] This embodiment provides a test device for the influence of disturbance on early-age concrete. Figure 1-Figure 2 As shown, it includes a rock-soil medium simulation block 2, which is a cylindrical block made of soil according to the proportion required by the test and is used to simulate the soil around the engineering concrete.
[0029] The rock and soil medium simulation block 2 is provided with a sample block placement cavity, and the sample block placement cavity is used to place the concrete sample block 1. In this embodiment, the sample block placement cavity is arranged at the central part of the rock and soil medium simulation block 2, and the sample block placement cavity passes through the upper and lower end surfaces of the rock and soil medium simulation block. The shape of the sample block placement cavity matches the shape of the concrete sample block 1. When the concrete sample block 1 is a cubic block, the sample block placement cavity is a cavity with a cubic structure. When the concrete sample block 1 is a cylindrical block, the sample block placement cavity is a cylindrical cavity.
[0030] The outer circumference of the rock-soil medium simulation block 2 is wrapped with a vibration transmission layer, and the vibration transmission layer includes a vibration adjustment medium layer 4 wrapped on the outer circumference of the rock-soil medium simulation block, and the outer circumference of the vibration adjustment medium layer 4 is wrapped with a vibration transmission medium layer 3.
[0031] The upper end surface of the vibration transmission medium layer 3 is used for placing the vibration generating mechanism 5, which can generate vibration impact on the vibration transmission medium layer 3, and the vibration transmission medium layer 3 can transmit the vibration to the vibration adjustment medium layer 4. After adjusting the vibration, the vibration adjustment medium layer 4 transmits the vibration to the concrete sample block 1 through the rock and soil medium simulation block 2.
[0032] In this embodiment, the vibration adjustment medium layer 4 adjusts the shock wave according to the difference between the shock wave characteristics generated by the vibration generating mechanism 5 and the shock wave characteristics required for the simulation test. Sand, cement, clay, engine oil and rubber particles with various fineness moduli are mixed according to a set ratio. The set ratio is set according to actual needs. Its main function is to adjust the intensity and vibration characteristics of the impact vibration generated by the vibration generating mechanism 5 by filling media of different properties, so that it better meets the test requirements.
[0033] The material of the vibration transmission medium layer 3 is obtained by converting the site soil of the actual engineering project vertically according to the similarity principle. Commonly used materials are barite powder, clay, quartz sand, talcum powder, fly ash, and ceramic particles mixed according to the set ratio. To simulate the layered characteristics of the site soil, plastic film, glossy paper, and mica sheets can also be mixed according to the set requirements. The main function of this area is to simulate the dynamic response characteristics of the site soil when it is affected by the shock wave.
[0034] The outer circumferential surface of the vibration transmission medium layer 3 is wrapped with a vibration consumption layer, and the radiated vibration energy can be absorbed and dissipated under the action of the vibration consumption layer, thereby avoiding the phenomenon of vibration feedback at the boundary.
[0035] The vibration consumption layer includes a flexible material layer wrapped on the outer circumference of the vibration transmission medium layer. In this embodiment, the flexible material layer is a rubber layer 6, and the outer circumference of the flexible material layer is wrapped with a loose sand layer 7. The loose sand layer 7 in this embodiment is made of sand with a natural repose angle greater than 45°. The radiated vibration energy is weakened by the rubber layer 6 and then transmitted to the loose sand layer 7 to be absorbed and dissipated, thereby avoiding vibration feedback at the boundary.
[0036] The test device also includes a vibration generating mechanism 5, such as Figure 3 As shown, the vibration generating mechanism includes an air pipe 5-1, one end of which is provided with a vibration membrane, and the vibration membrane in this embodiment is a metal membrane 5-2. The other end of the air pipe 5-1 is connected to an air source, and in this embodiment, the air source is an air compressor.
[0037] The area of the metal film 5-2 is larger than the cross-sectional area of the air outlet pipe of the air compressor, so the air pipe 5-1 adopts a conical tube, the end of the conical tube with a larger area is connected to the metal film 5-2, and the end with a smaller area is connected to the air outlet pipe of the air compressor.
[0038] In this embodiment, the air pipe 5-1 is installed with a valve, which is an electrically controlled valve 5-3. The electrically controlled valve 5-3 is connected to a control system, and the control system can control the opening and closing of the electrically controlled valve 5-3. After the electrically controlled valve 5-3 is opened, it is closed after a set time interval, so that the air compressor can output a set amount of gas to the rear of the electrically controlled valve 5-3, impacting the metal film 5-2, causing the metal film 5-2 to vibrate, and transmit the vibration to the vibration transfer medium layer 3.
[0039] The test device of this embodiment can use the gas generated by the air compressor to impact the vibration membrane, thereby using the vibration membrane to generate vibration impact on the vibration transmission layer 3, simulating the impact vibration of concrete (including but not limited to explosion, strong tamping, vehicle operation, etc.). Compared with the traditional application of triangular load to simulate impact vibration, the vibration impact generated by gas is more consistent with explosion impact, and the test results are more accurate. The impact intensity and type generated by the metal film 5-2 can be adjusted by adjusting the gas pressure, the diameter of the air pipe, the stiffness of the metal film, etc.
[0040] The test device also includes a detection mechanism, which includes an ultrasonic transducer and an ultrasonic probe used in conjunction with each other. The ultrasonic transducer is used to be fixed on one end of the concrete sample block, and the ultrasonic probe is used to be fixed on the other end of the concrete sample block. The ultrasonic transducer is connected to the ultrasonic generator.
[0041] The ultrasonic probe can record the ultrasonic wave velocity during the vibration gap, thereby reflecting the strength changes of early-age concrete.
[0042] In this embodiment, except for the portion in contact with the concrete specimen block 1 , the rest of the outer surface of the ultrasonic transducer and the ultrasonic probe are wrapped with a rubber vibration-damping layer to avoid the influence of impact vibration.
[0043] The device of this embodiment has a simple structure and low manufacturing cost, and can simulate more realistic vibration impact loads at a lower cost. In addition, multiple vibration generating mechanisms can be placed on the upper end surface of the vibration transmission medium layer as needed, and the influence of multiple vibration impact sources on the sample can be simply and efficiently realized, thereby reducing the cost of scientific research and promoting technological development in related fields.
[0044] Embodiment 2:
[0045] This embodiment provides a working method of the early age concrete disturbance effect test device described in Embodiment 1, comprising the following steps:
[0046] S1: The top and bottom of the early-age concrete specimen 1 were treated with ultrasonic coupling agent, and an ultrasonic transducer and an ultrasonic probe were attached respectively (both were wrapped with rubber on the outside to avoid impact and vibration).
[0047] S2: The early-age concrete specimen block 1 is buried in the specimen block placement cavity of the soil simulation medium block 2 which is proportioned according to the test requirements. The rock and soil medium simulation block 2 and the vibration transmission medium layer 3 are separated by the vibration adjustment medium layer 4. The medium properties in the vibration adjustment zone medium layer 4 can be adjusted according to the test requirements.
[0048] S3: After installation, start the impact vibration generating mechanism 5, that is, start the air compressor. The adjustable electric control valve 5-3 controls the air pipe to release a certain amount of gas with a set pressure according to the command of the control system, impacting the metal membrane 5-2, and generating impact vibration in the vibration transmission medium layer 3. After adjustment by the vibration adjustment medium layer 4, it is transmitted to the rock and soil medium simulation block 2, and then acts on the early age concrete specimen block 1; the radiated and divergent vibration energy is weakened by the elastic rubber layer 6 and then transmitted to the loose sand layer to be absorbed and dissipated, avoiding the vibration feedback phenomenon at the model boundary.
[0049] S4: When the vibration stops, start the ultrasonic generator, record the test time and the ultrasonic wave velocity in the concrete specimen, complete a test, and then return to S3 and repeat the cycle until the acquired data meets the test requirements.
[0050] S5: After taking out the early-age concrete specimen block 1, further laboratory test studies such as electron microscopy scanning and triaxial compression were carried out.
[0051] In this embodiment, a plurality of vibration generating mechanisms 5 can be conveniently arranged at any position to simulate the influence of superposition of impacts of multiple groups of vibration sources on early-age concrete.
[0052] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.
Claims
1. A test device for the influence of disturbance on early-age concrete. It is characterized in that It comprises a rock-soil medium simulation block, wherein a sample placement cavity is provided inside the rock-soil medium simulation block, a vibration transmission layer is wrapped around the outer circumference of the rock-soil medium simulation block, and a vibration consumption layer is wrapped around the outer circumference of the vibration transmission layer; It also includes at least one vibration generating mechanism, the vibration generating mechanism includes an air pipe, one end of the air pipe is connected to the air source, and the other end of the air pipe is used as an end portion in contact with the vibration transmission layer and is provided with a vibration membrane; The vibration transmission layer includes a vibration adjustment medium layer on the outer peripheral surface of the rock and soil medium simulation block and a vibration transmission medium layer on the outer peripheral surface of the vibration adjustment medium layer; The vibration adjustment medium layer is made of sand, cement, clay, engine oil and rubber particles of various fineness moduli mixed in a set ratio. By filling the medium with different properties, the intensity and vibration characteristics of the impact vibration generated by the vibration generating mechanism are adjusted to make it more in line with the test requirements; The material of the vibration transmission medium layer is obtained by converting the site soil of an actual engineering project vertically according to a similarity principle, and its main function is to simulate the dynamic response characteristics of the site soil when it is affected by a shock wave.
2. A test device for early age concrete subjected to disturbance as claimed in claim 1, It is characterized in that The device also comprises a detection mechanism, which comprises an ultrasonic transducer fixed at one end of the sample block and an ultrasonic probe fixed at the other end of the sample block, and the ultrasonic transducer is connected to the ultrasonic generator.
3. A test device for early age concrete subjected to disturbance as claimed in claim 2, It is characterized in that The ultrasonic probe and the ultrasonic transducer are wrapped with a rubber vibration-damping layer.
4. A test device for early age concrete subjected to disturbance as claimed in claim 1, It is characterized in that The vibration consumption layer includes a flexible material layer wrapped around the vibration transmission layer and a loose sand layer included around the flexible material layer.
5. A test device for early age concrete subjected to disturbance as claimed in claim 4, It is characterized in that The flexible material layer is a rubber layer.
6. A test device for early age concrete subjected to disturbance as claimed in claim 1, It is characterized in that The air pipe is a conical pipe, a vibrating membrane is fixed on the end with a larger area, and the end with a smaller area is connected to the air source.
7. A test device for early age concrete subjected to disturbance as claimed in claim 1, It is characterized in that A valve is provided in the trachea.
8. A test device for early age concrete subjected to disturbance as claimed in claim 1, It is characterized in that A protective sleeve is arranged on the outer periphery of the air pipe, the protective sleeve is fixedly connected to the air pipe, and the bottom end of the protective sleeve is flush with the end of the air pipe where the vibration membrane is installed.
9. A method for operating the early age concrete disturbance effect test device according to any one of claims 1 to 8, It is characterized in that The sample block is placed in the sample placement cavity of the rock and soil medium simulation block, at least one vibration generating mechanism is placed at a set position on the upper end surface of the vibration transmission layer, and the vibration membrane is in contact with the upper end surface of the vibration transmission layer. The air source introduces a set pressure gas into the air pipe within a set time interval to simulate the explosion impact, thereby generating a vibration impact on the vibration transmission layer. The vibration transmission layer transmits the vibration and applies the vibration impact to the sample block through the soil medium simulation layer. Multiple vibration impacts are applied to the sample block until the experimental requirements are met and the sample block is taken out.