Soft-package pre-embedded early-age concrete strain sensor

Abstract

The utility model provides a soft package pre-embedded early-age concrete strain sensor, which is used for measuring the strain of early-age concrete and comprises a silica gel rod, a resistance strain gauge pre-embedded in the silica gel rod, and a connecting cable connected with the resistance strain gauge and extending out of the silica gel rod, the resistance strain gauge is embedded along the axis of the silica gel rod. The utility model has the advantages that the elastic modulus of the sensor is low, the rigidity matching between the sensor and the concrete to be measured in the early age and the service stage can be effectively realized, and the fidelity transmission and the high-precision measurement of the concrete strain are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of concrete stress measurement, and particularly relates to a soft-pack embedded early-age concrete strain sensor. Background Technique

[0002] In the fields of civil engineering, hydraulic engineering, ocean engineering, etc., after the casting of mass concrete, due to the hydration effect, the temperature rises sharply and the water content drops sharply during the early age, resulting in non-uniform deformation and internal damage of the structure under the multi-field coupling of temperature, humidity and stress, posing potential hazards to the safety and durability of the structure. Therefore, accurately detecting and scientifically evaluating the deformation and damage of mass concrete structures in the early age is an extremely important technical link in all concrete structure projects.

[0003] Due to the low stiffness of early-age concrete, traditional strain sensors cannot achieve stiffness matching with it, and the monitored data is much smaller than the actual deformation of the concrete structure, resulting in data distortion or even incorrect results. Secondly, the sharp rise and fall of temperature during the hydration process have a volume deformation effect on the base material of traditional sensors, resulting in the inclusion of base deformation information in the detection results, seriously affecting the accuracy and even correctness of the detected data information. Content of the Utility Model

[0004] The purpose of the utility model is to provide a soft-pack embedded early-age concrete strain sensor according to the deficiencies of the above-mentioned existing technologies. By embedding a resistance strain gauge in a cylindrical silica gel rod, due to the characteristics of the silica gel rod with low elastic modulus and high temperature resistance, it can match the stiffness of early-age concrete, thereby ensuring the accuracy of measurement data.

[0005] The purpose of the utility model is achieved by the following technical solutions:

[0006] A soft-pack embedded early-age concrete strain sensor, which is used to measure the strain of early-age concrete. The sensor includes a silica gel rod, a resistance strain gauge embedded inside the silica gel rod, and a connecting cable connecting the resistance strain gauge and extending outside the silica gel rod. The resistance strain gauge is buried along the axis of the silica gel rod.

[0007] The elastic modulus of the silica gel rod is 1-2 MPa.

[0008] The resistance strain gauge is a uniaxial resistance strain gauge.

[0009] The resistance strain gauge and the silica gel rod are fixedly bonded with glue.

[0010] An insulating and waterproof coating is provided outside the resistance strain gauge.

[0011] The silica gel rod is cylindrical, with a diameter of 20 mm and a length of 50 mm.

[0012] The grid wire size of the resistance strain gauge is 20×5 mm.

[0013] The connecting cable extends out from the side of the silica gel rod.

[0014] The advantages of the present utility model are as follows: The elastic modulus of the sensor is low, which can effectively achieve the stiffness matching between the sensor and the concrete to be measured in the early age and service stage, ensuring the faithful transmission and high-precision measurement of concrete strain. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of the sensor in the present utility model;

[0016] Figure 2 It is a front view schematic diagram of the sensor in the present utility model;

[0017] Figure 3 It is a side view schematic diagram of the sensor in the present utility model;

[0018] Figure 4 It is a size schematic diagram of the sensor in the present utility model;

[0019] Figure 5 It is a schematic diagram of the working principle of the sensor in the present utility model. Detailed Embodiment

[0020] The features of the present utility model and other related features are further described in detail below with reference to the drawings through embodiments for the understanding of those skilled in the same industry:

[0021] As Figures 1-5 shown, the marks 1-3 in the figure respectively represent: silica gel rod 1, resistance strain gauge 2, connecting cable 3.

[0022] Embodiment: As Figures 1-5 shown, this embodiment relates to a soft-pack embedded early-age concrete strain sensor for measuring the internal strain force of early-age concrete. The sensor includes a silica gel rod 1, a resistance strain gauge 2 embedded inside the silica gel rod 1, and a connecting cable 3 connecting the resistance strain gauge 2 and extending outside the silica gel rod 1. Among them, the connecting cable 3 is connected to an external measurement circuit, etc., to obtain the signal on the resistance strain gauge 2. And the resistance strain gauge 2 is buried along the axis of the silica gel rod 1. Since the elastic modulus of the silica gel rod 1 is low, it can effectively achieve the stiffness matching between the sensor and the concrete to be measured in the early age and service stage, ensuring the faithful transmission and high-precision measurement of concrete strain.

[0023] In this embodiment, the resistive strain gauge 2 is directly embedded in the silica gel rod 1 to form a structure enclosed by a soft package. Among them, the axis of the silica gel rod 1 lies on the plane where the resistive strain gauge 2 is located. Specifically, the silica gel rod 1 can be evenly divided into two halves along the axis first, and then the resistive strain gauge 2 is placed between the two halves of the silica gel rod 1, and the two halves of the silica gel rod 1 and the resistive strain gauge 2 are bonded and fixed with glue.

[0024] In this embodiment, the elastic modulus of the silica gel rod 1 is 1-2 MPa. That is to say, after concrete pouring, it experiences stages such as fluidity, curing, increase in elastic modulus, and stabilization of elastic modulus. The fluid stage has a short duration and the deformation in this stage does not affect the mechanical properties of the concrete in the later stage. The elastic modulus of the concrete is usually very low during the curing stage. Therefore, in view of the low stiffness of early-age concrete, this embodiment selects a silica gel rod 1 with a low elastic modulus (1.0-2.0 MPa) as the base material and the concrete deformation conduction medium, so that the stiffness of the sensor is less than that of the early-age concrete during the whole process of concrete curing, ensuring the stiffness matching between the sensor and the measured concrete medium. At the same time, the outer surface of the sensor body (i.e., the outer surface of the silica gel rod 1) is closely bonded to the concrete to ensure the transfer of the deformation displacement of the concrete, thereby ensuring the reliability and accuracy of the monitoring data.

[0025] In some alternative embodiments, the silica gel rod 1 has the property of high temperature resistance.

[0026] In this embodiment, the resistive strain gauge 2 is a uniaxial resistive strain gauge to achieve unidirectional stress monitoring. Due to the cylindrical structure of the silica gel rod 1, the sensor can be easily buried and installed on site, and the sensor can be buried in different directions according to the needs of test monitoring, and then combined into any bidirectional or triaxial monitoring system.

[0027] In this embodiment, the resistive strain gauge 2 and the silica gel rod 1 are bonded and fixed with glue to ensure that the stress received by the silica gel rod 1 is faithfully transmitted to the resistive strain gauge 2. Among them, the outside of the resistive strain gauge 2 is subjected to a sealing and waterproof treatment to avoid damage to the resistive strain gauge 2. Optionally, an insulating and waterproof coating is provided outside the resistive strain gauge 2. In some embodiments, this insulating and waterproof coating can be directly composed of glue, and in other embodiments, an additional insulating waterproof material can be coated outside the resistive strain gauge 2.

[0028] In this embodiment, optionally, the silica gel rod 1 is cylindrical, the diameter of the silica gel rod 1 is 20 mm, and the length is 50 mm. Due to the cylindrical structure of the silica gel rod 1, the sensor can be easily buried and installed on site.

[0029] In some embodiments, the grid wire size of the resistive strain gauge 2 is 20×5 mm. Optionally, the grid wires of the resistive strain gauge 2 are arranged in a grid pattern in the diameter direction of the silica gel rod 1.

[0030] In this embodiment, optionally, the connecting cable 3 extends from the side surface of the silica gel rod 1. Specifically, one end of the connecting cable 3 is connected to the resistance strain gauge 2, and the other end first extends a certain distance along the direction parallel to the axis of the silica gel rod 1, and then bends 90° and extends radially out of the silica gel rod 1.

[0031] The working principle of the sensor in this embodiment is introduced below by way of example.

[0032] Within 40 hours after concrete pouring, the internal temperature will rise from the atmospheric temperature to about 70 °C, and then the temperature will gradually drop and drop to normal temperature in about 170 hours. During the temperature rise and fall process, the main structure of the sensor will correspondingly generate temperature deformation, which directly affects the accuracy and reliability of the strain measurement results. In this embodiment, a standard test method for simulating the concrete temperature change process is adopted, and the sensor thermal strain change function relationships corresponding to the temperature rise and fall processes are respectively established to eliminate the influence of thermal deformation during the detection process and ensure the reliability and high precision of the monitoring data.

[0033] Specifically, the sensor is embedded in the concrete. After the concrete is poured, the sensor will receive the internal forces (gravity, shrinkage, etc.) P c and the temperature load P T of the concrete structure. The coupling effect is transmitted to the resistance strain gauge through the outer surface of the sensor body, causing the deformation of the resistance strain gauge.

[0034] Let: the strain generated by the internal force of the structural concrete be ε c , the thermal strain of the sensor body be ε T , and the directly monitored strain be ε. Then the strain of the concrete structure after eliminating the thermal strain is: ε c = ε - ε T .

[0035] The detection method of the sensor in this embodiment is introduced below by way of example.

[0036] (1) After the corresponding parts are processed according to the design technical parameters and pass the inspection, the factory assembles them into a prefabricated resistance strain sensor, that is, the sensor in the above embodiment.

[0037] (2) Calibrate the sensitivity of the resistance strain sensor at normal temperature.

[0038] (3) Set the temperature simulation environment, and respectively calibrate the temperature sensitivity of the resistance strain sensor during the whole process of temperature rise and fall of the sensor and establish the temperature change function relationship.

[0039] (4) Establish a sensor temperature sensitivity correction method.

[0040] (5) Provide on-site monitoring application for the project after the product passes the inspection.

[0041] In this embodiment, by calibrating the temperature sensitivity before leaving the factory, the influence of the base temperature of the strain gauge can be effectively eliminated.

[0042] In summary, the beneficial effects of the present utility model are as follows: The elastic modulus of the sensor is low, which can effectively achieve the stiffness matching between the sensor and the concrete to be measured in the early age and service stage, ensuring the faithful transmission and high-precision measurement of concrete strain; The cylindrical structure is adopted, and the on-site embedding and installation are simple, and it can be combined into any two-way or three-way monitoring system according to the needs of test monitoring.

[0043] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the field to which the present utility model belongs. The "first", "second" and similar terms used in the description and claims of the patent application of the present utility model do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, the terms such as "a" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "up", "down", "left" and "right" are only used to indicate relative position relationships, and when the absolute position of the object to be described changes, the relative position relationships also change accordingly.

[0044] The above is the preferred embodiment of the present utility model. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present utility model.

Claims

1. A soft-pack embedded early-age concrete strain sensor, characterized in that, The sensor is used for measuring the strain of early-age concrete. The sensor includes a silica gel rod, a resistance strain gauge embedded inside the silica gel rod, and a connecting cable connecting the resistance strain gauge and extending outside the silica gel rod. The resistance strain gauge is buried along the axis of the silica gel rod.

2. The sensor according to claim 1, characterized in that, The elastic modulus of the silica gel rod is 1-2 MPa.

3. The sensor according to claim 1, characterized in that The resistance strain gauge is a uniaxial resistance strain gauge.

4. The sensor according to claim 1, wherein The resistance strain gauge and the silica gel rod are fixed by adhesive bonding.

5. The sensor according to claim 1, wherein An insulating and waterproof coating is provided outside the resistance strain gauge.

6. The sensor according to claim 1, characterized in that, The silica gel rod is in a cylindrical shape. The diameter of the silica gel rod is 20 mm and the length is 50 mm.

7. The sensor according to claim 1, characterized in that, The grid wire size of the resistance strain gauge is 20×5 mm.

8. The sensor according to claim 1, wherein The connecting cable extends out from the side surface of the silica gel rod.

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