A test method and test device for measuring the friction between concrete and a pumping conduit

Abstract

The application provides a test method and a test device for measuring the friction between concrete and a pumping pipe, wherein the roughness of the inner wall of a measuring pipe is consistent with that of a pumping steel pipe, strain gauges are arranged at equal intervals along the length direction of the measuring pipe outside the measuring pipe, the strain gauges are connected with a strain acquisition instrument, annular fixing steel plates which are suitable for the shape and size of the measuring pipe are prepared, the measuring pipe is fixed through two annular fixing steel plates, a limiting rod and a matched nut, concrete with different pumping speeds is pumped, the strain value in the pumping process is recorded through the strain acquisition instrument, and the friction between the concrete and the pipe in the concrete pumping process is calculated according to the measured strain value. The provided test method and test device can directly and accurately measure the friction between the concrete and the pipe, and are convenient for adjusting the pumping speed and the concrete proportion, can provide direct numerical values for calculating the pressure loss along the pipeline in the concrete pumping process, and guarantee the safe and stable implementation of the concrete pumping project.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete pumping, and particularly provides a test method and a test device for measuring friction between concrete and a pumping pipe. BACKGROUND

[0002] In recent years, the concrete pumping technology is widely applied in building construction, and compared with the traditional technology, the concrete pumping technology greatly improves the construction level of concrete and plays an important role in building construction.

[0003] When pumping, the concrete flows in the pump pipe to generate friction and further generate a pumping pressure loss. Accurate measurement of the frictional resistance between the concrete and the pipe is a key factor for calculating the pumping pressure loss. The traditional method usually measures the viscous force of the concrete by using a rheometer and then obtains the frictional resistance through theoretical conversion. However, there are certain theoretical assumptions in the conversion process, which leads to a difference between the measured value and the actual value. In addition, the rotation speed of the stirring blade is usually used to reflect the influence of the concrete speed, and the influence of the real active flow speed of the concrete on the frictional resistance cannot be reflected.

[0004] In summary, the traditional method cannot accurately calculate the friction between the pumped concrete and the pipe, and it is also inconvenient to calculate the friction between the concrete and the pipe under the working conditions of changing the pumping speed and the concrete formula, so as to accurately calculate the pumping pressure loss and ensure the safe and stable progress of the pumped concrete project. SUMMARY

[0005] To solve the above technical problems, the present application provides a test method and a test device for measuring the friction between the concrete and the pumping pipe, so as to accurately and directly measure the frictional resistance between the concrete and the pipe, provide direct numerical values for calculating the pressure loss along the way in the concrete pumping process, and conveniently calculate the friction between the concrete and the pipe under the working conditions of changing the pumping speed and the concrete formula.

[0006] To achieve the above purpose, in a first aspect, the present application provides a test method for measuring the friction between the concrete and the pumping pipe, comprising the following steps:

[0007] S1. processing the inner wall of the measuring pipe so that the roughness of the inner wall of the measuring pipe is consistent with that of the pumping steel pipe;

[0008] S2. arranging strain gauges on the outer wall of the measuring pipe at equal intervals along the length direction of the measuring pipe, and connecting the strain gauges with a strain acquisition instrument;

[0009] S3. fixing the measuring pipe by using two annular fixed steel plates, a limiting rod and a matched nut which are adapted to the shape and size of the measuring pipe;

[0010] S4. sequentially connecting the pumping device, the pumping auxiliary pipe, the measuring pipe and the flow monitoring device, and supporting the pipes by the supporting device;

[0011] S5. pumping the concrete at different speeds, and recording the strain values in each pumping process by the strain collector;

[0012] S6. calculating the friction between the concrete and the pipes during the pumping of the concrete according to the measured strain values.

[0013] Optionally, before pumping the concrete, a set pre-pressure is applied to the measuring pipe by the nut on the limiting rod, and the strain value generated by the pre-pressure is recorded by the strain collector.

[0014] Optionally, S5 comprises: the flow monitoring device calculates the speed of the concrete passing through the measuring pipe by the following formula:

[0015]

[0016] wherein v is the flow speed of the concrete in the measuring pipe, Q is the volume of the concrete flowing through a certain section of the pipe per unit time, and A is the cross-sectional area of the measuring pipe.

[0017] Optionally, S5 comprises: the strain value when calculating the pressure loss uses an average value, which is calculated by the following formula:

[0018]

[0019]

[0020] wherein ε n1 , ε n2 , ε n3 , and ε n4 are the strain values read by the strain collector at the same section during the pumping of the concrete, and ε m1 , ε m2 , ε m3 , and ε m4 are the strain values read by the strain collector at the same section after applying the pre-pressure.

[0021] Optionally, S6 comprises: the friction when the concrete is pumped to a certain cross section of the measuring pipe is calculated by the following formula:

[0022] f i = ΔE·E = |(ε n - ε m )|·E

[0023] wherein f i is the friction when the concrete is pumped to a certain cross section of the measuring pipe, ΔE is the strain increment, and E is the elastic modulus of the PVC pipe material, and ε nε is the average strain of the cross section when the concrete is pumped m ε is the average strain of the cross section after the pre-pressure is applied.

[0024] Optionally, S6 comprises: the frictional force when the concrete is pumped is calculated according to the following formula:

[0025]

[0026] wherein f is the frictional force when the concrete is pumped, f i wherein f is the frictional force when the concrete is pumped to a certain cross section of the measuring pipe, and n is the number of strain gauges arranged along the length direction of the measuring pipe.

[0027] In order to achieve the above-mentioned purpose, the second aspect of the present application provides a test device for measuring the friction between concrete and a pumping pipe, which is suitable for the method for calculating the friction between concrete and a pipe, comprising a measuring pipe, a pumping auxiliary pipe, a pumping device and a flow monitoring device; the measuring pipe is connected with the pumping device through the pumping auxiliary pipe; the measuring pipe is fixed by two annular fixed steel plates and a limiting rod and its matched nuts; the roughness of the inner wall of the measuring pipe is consistent with that of the pumping steel pipe; the flow monitoring device is used for measuring the speed of the concrete when it passes through the measuring pipe; the outer wall of the measuring pipe is arranged with strain gauges at equal intervals along the length direction; the strain gauges are connected with a strain acquisition instrument, so as to record the strain values of each strain gauge during the pumping process through the strain acquisition instrument when pumping concrete at different speeds.

[0028] Optionally, the measuring pipe and the pumping auxiliary pipe are consistent with the diameter and the roughness of the inner surface of the actual concrete pump steel pipe; the measuring pipe and the pumping auxiliary pipe are both PVC pipe materials.

[0029] Optionally, the inner diameter of the annular fixed steel plate is the same as the inner diameter of the measuring pipe and the pumping auxiliary pipe, and the thickness is 2-4 mm.

[0030] Optionally, the measuring range of the strain gauge is 0-20000 micro-strain, and the accuracy is 1 micro-strain; the strain gauges are arranged at equal intervals along the flow direction of the concrete.

[0031] The provided test method and test device, the pumping equipment pumps the concrete to the measuring pipe through the pumping auxiliary pipe, the measuring pipe and the pumping auxiliary pipe are arranged to be consistent with the diameter and the inner surface roughness of the concrete pump steel pipe, the speed of the concrete passing through the measuring pipe is measured through the flow monitoring device, the strain gauges arranged at equal intervals along the length direction of the outer wall of the measuring pipe and the connected strain acquisition instrument record the strain values of each strain gauge in the pumping process when pumping the concrete at different speeds, and the friction between the concrete and the pipe during the concrete pumping process can be accurately calculated according to the measured strain values. The relationship between the pumping speed and the frictional resistance can be established according to the test results, and the pumping pressure loss of different pumping conditions can be accurately calculated by changing the concrete proportion and the concrete material proportion, so as to finally ensure that the concrete pumping engineering is safely and stably carried out. BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in conjunction with the drawings and specific implementation methods. The drawings described herein are used to provide further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application.

[0033] Figure 1 The flowchart of the test method for measuring the friction between the concrete and the pumping pipe provided by the present application.

[0034] Figure 2 The three-dimensional schematic view of the test device for measuring the friction between the concrete and the pumping pipe provided by the present application.

[0035] Figure 3 The left view of the test device for measuring the friction between the concrete and the pumping pipe.

[0036] Figure 4 The top view of the test device for measuring the friction between the concrete and the pumping pipe.

[0037] In the figure: 1 is the pumping equipment, 2 is the pumping auxiliary pipe, 3 is the limiting rod, 4 is the right end ring fixed steel plate, 5 is the strain gauge, 6 is the measuring pipe, 7 is the left end ring fixed steel plate, 8 is the left end ring fixed steel plate fixed and pre-pressed nut, 9 is the flow monitoring device, 10 is the right end ring fixed steel plate fixed and pre-pressed nut, 11 is the pipe support device; 3, 4, 10 jointly constitute the right end fixed and pre-pressed device; 3, 7, 8 jointly constitute the left end fixed and pre-pressed device. DETAILED DESCRIPTION

[0038] The embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application or its application or uses. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Unless otherwise specified, the relative arrangement, numerical expression and values of the components and steps described in these embodiments do not limit the scope of the present application.

[0039] In the construction, the concrete flows in the pump pipe during the concrete pumping process, and the friction is generated, and then the pumping pressure loss is generated. Accurately calculating the friction resistance between the concrete and the pipe is a key factor for calculating the pumping pressure loss. The traditional method cannot accurately calculate the friction between the concrete and the pipe during the pumping, and it is not convenient to calculate the friction between the concrete and the pipe under the working conditions of changing the pumping speed and the concrete formula, so as to accurately calculate the pumping pressure loss and ensure the safe and stable operation of the pumping concrete project.

[0040] Therefore, the present application provides a test method and a test device for measuring the friction between the concrete and the pumping pipe, so as to accurately and directly measure the friction between the concrete and the pipe. The test device for measuring the friction between the concrete and the pumping pipe provided by the present application comprises a measuring pipe 6, a pumping auxiliary pipe 2, a pumping device 1 and a flow monitoring device 9. The measuring pipe 6 is connected with the pumping device 1 through the pumping auxiliary pipe 2. The measuring pipe 6 is fixed by two annular fixed steel plates 47, a limiting rod 3 and a matched nut 8. The inner wall roughness of the measuring pipe 6 is consistent with that of the pumping steel pipe. The flow monitoring device 9 is used to measure the speed of the concrete when passing through the measuring pipe 6. The outer wall of the measuring pipe 6 is arranged with strain gauges 5 at equal intervals along the length direction. The strain gauges 5 are connected with a strain acquisition instrument, so as to record the strain values of the strain gauges 5 during the pumping process through the strain acquisition instrument when pumping the concrete at different speeds.

[0041] Among them, the measuring pipe 6 and the pumping auxiliary pipe 2 are consistent with the diameter and the inner surface roughness of the concrete pump steel pipe, and are both PVC pipe materials. The measuring pipe 6 is made of PVC material, which has a large elastic expansion range, so as to ensure that the strain generated by the friction between the pumping concrete and the measuring pipe 6 is within the measurable range of the strain gauges 5.

[0042] In some preferred embodiments, before pumping concrete, a certain pre-pressure is applied to the measuring pipe 6 through the nuts 8, 10 on the limiting rod 3, and the strain value at this time is recorded by the strain collector. This measure makes the deformation range of the measuring pipe 6 under the pre-pressure state closer to the original state of the free state than the friction resistance generated by the same concrete pumping in the free state. The measuring pipe 6 is a PVC pipe, and in the deformation range close to the original state, the relationship between the strain and the friction resistance received by the concrete is closer to the linear relationship, which can more accurately obtain the friction resistance of the concrete pumping through the strain. This measure ensures that the friction resistance generated by pumping concrete is in the high-precision measurement range of the strain gauge 5.

[0043] In some preferred embodiments, the flow monitoring device can monitor the flow velocity of the concrete, and the relationship between the pumping speed and the friction resistance can be established according to the test results. At the same time, the concrete mixture ratio is changed, and the relationship between the concrete material mixture ratio and the friction resistance can be established, so that the calculation of the friction resistance under different working conditions can be easily realized, and it is more suitable for the needs of engineering reality.

[0044] The basic technical scheme of the test method for measuring the friction between the concrete and the pumping pipe provided by the application includes the following steps:

[0045] S1. Processing the inner wall of the measuring pipe 6 so that the roughness of the inner wall of the measuring pipe 6 is consistent with that of the pumping steel pipe. Specifically, the processing method can be completed by grinding or other roughening treatment methods, such as chemical treatment of the surface of the measuring pipe. The reason for making the roughness of the inner wall of the measuring pipe 6 consistent with that of the pumping steel pipe is to realize the high-precision same nature of the test environment and the real pumping application, so as to obtain accurate test results.

[0046] S2. The strain gauges 5 are arranged at equal intervals along the length direction of the measuring pipe 6, and the strain gauges 5 are connected with the strain collector. The strain gauges are used to monitor the strain of the measuring pipe at different positions in the whole length during the concrete pumping process, so as to accurately obtain the length change value of the measuring pipe, and to obtain accurate calculation results.

[0047] S3. The measuring tube 6 is fixed by two annular fixed steel plates, limiting rods 3 and their matching nuts 8, 10 which are adapted to the shape and size of the measuring tube 6; in some preferred embodiments, a set pre-pressure is applied to the measuring tube 6 by the nuts 8, 10 on the limiting rods 3 before pumping the concrete, and the strain value generated by the pre-pressure is recorded by the strain collector. By applying the pre-pressure to the measuring tube 6 as described above, the measuring tube 6 is in a state of being compressed in the axial direction and being shortened under pressure when pumping the concrete, and the concrete generates a frictional force on the measuring tube 6 which is converted into an axial tensile force to gradually restore the original length, and then converted into an axial elongation. The entire stress process of the measuring tube 6 under pre-pressure is: axial compression - stress balance - axial tension, and the corresponding strain process is: shortening - original length - elongation. The entire deformation process of the measuring tube 6 without pre-pressure is: stress balance - axial tension, and the corresponding strain process is: original length - axial elongation. Thus, the deformation range of the measuring tube 6 under pre-pressure generated by the same tensile force caused by pumping the concrete is closer to the original state of the free state than the deformation range of the measuring tube 6 in the free state generated by the same frictional force of the concrete. The measuring tube 6 is a PVC tube, and in the deformation range close to the original state, the relationship between the strain and the frictional force of the concrete is closer to a linear relationship, and the frictional force of the concrete during pumping can be more accurately obtained by strain. On the contrary, if the measuring tube 6 is in a free state, the deformation range is far from the original state, and the relationship between the strain and the frictional force of the concrete no longer has a state close to linear relationship, so the size of the frictional force of the concrete during pumping cannot be accurately obtained by strain. For the same reason, applying pre-pressure to the measuring tube 6 also makes the measured strain range relatively large, which is more suitable for tests of different pumping concrete speeds and different concrete mix ratios.

[0048] S4. The pumping device 1, the pumping auxiliary pipe 2, the measuring tube 6 and the flow monitoring device are connected in sequence, and the pipeline is supported by the supporting device 11. Through the above structure, the pumping environment in engineering application can be established, and the conversion of different pumping speeds and different concrete mix ratios can be facilitated to realize the calculation of the frictional force under different pumping conditions.

[0049] S5. Pumping concrete at different speeds, and recording the strain values in each pumping process by the strain collector; wherein the flow monitoring device calculates the speed of the concrete passing through the measuring tube 6 by the following formula: wherein v is the flow speed of the concrete in the measuring tube 6, Q is the volume of the concrete flowing through a certain section of the pipeline per unit time, and A is the cross-sectional area of the measuring tube 6. Further, the average value of the strain value when calculating the pressure loss is calculated by the following formula: wherein ε n1 , ε n2 , ε n3 , εn4 All values ​​are strain values ​​read by a strain acquisition instrument at the same cross-section during concrete pumping, ε m1 , ε m2 , ε m3 , ε m4 All values ​​are strain values ​​read by the strain acquisition instrument at the same cross-section after prestressing was applied.

[0050] S6. Calculate the frictional force between the concrete and the pipeline during the concrete pumping process based on the measured strain value.

[0051] Optionally, S6 includes: the frictional resistance when concrete is pumped to a certain cross-section of the measuring pipe 6 is calculated by the following formula:

[0052] f i =Δε·E=|(ε n -ε m )|·E

[0053] Among them, f i Δε represents the frictional resistance when concrete is pumped to a certain cross-section of measuring pipe 6, Δε is the strain increment, E is the elastic modulus of the PVC pipe material, and ε n ε represents the average strain during concrete pumping at this cross-section. m This represents the average strain of the cross section after applying preload.

[0054] Optionally, S6 includes: the frictional resistance during concrete pumping is calculated using the following formula:

[0055]

[0056] Where f is the frictional resistance during concrete pumping, f i η is the frictional resistance when concrete is pumped to a certain cross section of the measuring pipe 6, and n is the number of strain gauges 5 arranged along the length of the measuring pipe 6.

[0057] Compared with traditional empirical calculation methods, the experimental apparatus and method provided by this invention, in which the measuring tube 6 and the pumping auxiliary tube 2 are configured to match the diameter and inner surface roughness of the concrete pump steel pipe, measure the velocity of concrete passing through the measuring tube 6 using a flow monitoring device, and record the strain values ​​of concrete pumped at different velocities using strain gauges 5. Based on the measured strain values, the frictional force between the concrete and the pipeline during concrete pumping can be accurately calculated. This experimental apparatus and method allows for convenient changes in concrete mix proportions and material ratios, thereby accurately calculating the pumping pressure loss under different pumping conditions, ultimately ensuring the safe and stable operation of concrete pumping projects. The apparatus and method are simple in structure, easy to operate, reusable, and highly accurate.

[0058] The test method for measuring the friction between concrete and a pumping pipeline according to the present application is described as follows: according to the shape and size of the measuring pipe 6, the annular fixing steel plates 4 and 7 required by the device are prepared, and the length of the limiting rod 3 is determined; the inner wall of the measuring pipe 6 is polished, and a profilometer is used for inspection until the roughness of the inner wall of the measuring pipe is consistent with that of the pumping steel pipe. After polishing, the strain gauges 5 are arranged at equal intervals along the length direction of the measuring pipe, and the strain acquisition instrument is connected. After the strain gauges 5 are connected, the measuring pipe 6 is fixed by using the two annular fixing steel plates 4 and 7 and the limiting rod 3 and the matched nuts 8 and 10. The pumping equipment 1, the pumping auxiliary pipe 2, the measuring pipe 6 and the flow monitoring device 9 are connected in sequence, and the pipeline is supported by the supporting device 11. In order to ensure that the measuring pipe 6 does not shake, and considering the influence of the measurement accuracy of the strain gauges 5 on the calculation results, before pumping the concrete, a certain pre-pressure is applied to the measuring pipe 6 through the nuts 8 and 10 on the limiting rod 3, and the strain value at this time is recorded by the strain acquisition instrument. The pumping of the concrete is started, and the strain value during pumping is recorded by the strain acquisition instrument. The volume of the concrete in a unit of time is measured by 9, and then the pumping speed of the concrete is calculated. The friction between the concrete and the pipeline during the pumping of the concrete is calculated, and the relationship between different pumping speeds and the frictional resistance is established.

[0059] The above drawings and specific embodiments are only used to illustrate the present application, and the present application is not limited thereto. Subtle changes to the present application within the spirit and scope of the application defined by the claims of the present application fall within the protection scope of the present application.

Claims

1. A test method for measuring the friction between concrete and a pumping conduit, characterized in that, The method comprises the following steps: S1. Processing the inner wall of the measuring pipe (6) so that the roughness of the inner wall of the measuring pipe (6) is consistent with that of the pumping steel pipe; S2. Arranging strain gauges (5) on the outer wall of the measuring pipe (6) at equal intervals along the length direction of the measuring pipe (6) and connecting the strain gauges (5) with a strain acquisition instrument; S3. Fixing the measuring pipe (6) by two annular fixing steel plates, a limiting rod (3) and its matched nut (8) which are adapted to the shape and size of the measuring pipe (6); S4. Connecting the pumping device (1), the pumping auxiliary pipe (2), the measuring pipe (6) and the flow monitoring device (9) in sequence and supporting the pipes by a supporting device (11); S5. Pumping concrete at different speeds and recording the strain values in each pumping process by the strain acquisition instrument; S6. Calculating the friction force between the concrete and the pipes in the concrete pumping process according to the measured strain values; S4 comprises: before pumping the concrete, exerting a set pre-pressure on the measuring pipe (6) by the nut (8) on the limiting rod (3) and recording the strain value generated by the pre-pressure by the strain acquisition instrument; S6 comprises: the frictional resistance when the concrete is pumped to a certain cross section of the measuring pipe (6) is calculated by the following formula: , where f i is the friction force of the concrete being pumped to a certain cross section of the measuring pipe (6), is the strain increment, E is the modulus of elasticity of the PVC pipe material, is the average strain of the concrete being pumped to this cross section, is the average strain of this cross section after the pre-stress has been applied.

2. The test method for measuring the friction between concrete and a pumping conduit of claim 1, wherein, S5 comprises: the flow monitoring device (9) calculates the speed of the concrete flowing through the measuring pipe (6) by the following formula: , Wherein, v is the flow speed of the concrete in the measuring pipe (6), Q is the volume of the concrete flowing through a certain section of the pipe per unit time, and A is the cross-sectional area of the measuring pipe (6).

3. The method of calculating the friction of concrete with a pipe according to claim 2, characterized in that, S5 comprises: the average value of the strain value when the pressure loss is calculated is calculated by the following formula: , , wherein ε n1 , ε n2 , ε n3 , ε n4 are the strain values read by the same section strain acquisition instrument during concrete pumping, ε m1 , ε m2 , ε m3 , ε m4 are the strain values read by the same section strain acquisition instrument after pre-pressing.

4. The test method for measuring the friction between concrete and a pumping conduit according to claim 3, wherein S6 Comprises: the frictional resistance when the concrete is pumped is calculated by the following formula: , where f is the frictional resistance when the concrete is pumped, f i is the frictional resistance when the concrete is pumped to a certain cross section of the measuring pipe (6), and n is the number of strain gauges (5) arranged along the length of the measuring pipe (6).

5. A test device for measuring the frictional force between concrete and pumping pipes, which is suitable for the method for calculating the frictional force between concrete and pipes according to any one of claims 1 to 4, characterized in that: It comprises a measuring pipe (6), a pumping auxiliary pipe (2), a pumping device (1) and a flow monitoring device (9); The measuring pipe (6) is connected with the pumping device (1) through the pumping auxiliary pipe (2); The measuring pipe (6) is fixed by two annular fixing steel plates and a limiting rod (3) and its matched nut (8), and the roughness of the inner wall of the measuring pipe (6) is consistent with that of the pumping steel pipe; The flow monitoring device (9) is used for measuring the speed of the concrete flowing through the measuring pipe (6); The outer wall of the measuring pipe (6) is arranged with strain gauges (5) at equal intervals along the length direction, and the strain gauges (5) are connected with a strain acquisition instrument to record the strain values of each strain gauge (5) in the pumping process when pumping concrete at different speeds by the strain acquisition instrument.

6. The test apparatus for measuring the friction between concrete and a pumping conduit of claim 5, wherein: The measuring pipe (6) and the pumping auxiliary pipe (2) are consistent with the diameter and the roughness of the inner surface of the actual concrete pumping steel pipe, and the measuring pipe (6) and the pumping auxiliary pipe (2) are both PVC pipe materials.

7. The test device for measuring the friction between concrete and a pumping conduit according to claim 5, characterized in that: The inner diameter of the annular fixing steel plate is the same as that of the measuring pipe (6) and the pumping auxiliary pipe (2), and the thickness is 2-4 mm.

8. The test apparatus for measuring the friction between concrete and a pumping conduit of claim 5, wherein: The measuring range of the strain gauges (5) is 0-20000 micro-strain, and the accuracy is 1 micro-strain, and the strain gauges (5) are arranged at equal intervals along the concrete flow direction.

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