Pumping resistance calculation method for self-compacting concrete

Abstract

The invention provides a self-compacting concrete pumping resistance calculation method, which belongs to the field of pumping and comprises the following steps: S1, establishing an initial pumping parameter model according to pipeline geometric parameters of a pumping pipeline, initial physical characteristics of self-compacting concrete and pumping process parameters; s2, pumping working condition data are collected in real time and subjected to digital filtering processing, and the filtered concrete flow velocity is obtained; s3, calculating the dynamic plastic viscosity of the self-compacting concrete under the current working condition by utilizing a dynamic rheological evolution model according to the pumping time, the pumping environment temperature and the relative humidity; and S4, according to the initial pumping parameter model, the dynamic plastic viscosity and the filtered concrete flow velocity, pressure losses of different sections of the pumping pipeline are calculated, and the total pumping resistance is obtained based on the pressure losses of all the sections. According to the method, the calculation accuracy of the total pumping resistance of the pumping pipeline is improved through the concrete dynamic rheological characteristics, the environment temperature and humidity effect, the pipeline geometric parameters and the pumping process parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of pumping, and in particular to a method for calculating the pumping resistance of self-compacting concrete. Background Art

[0002] As a new type of high-performance concrete, self-compacting concrete has good fluidity, filling property, economy and environmental protection, and is widely used in large bridges, super high-rise buildings, water conservancy projects and other fields. Especially in the construction of long-span concrete-filled steel tube arch bridges, due to its excellent fluidity and self-compacting characteristics, it can effectively fill dense steel bars and complex cross-sections, ensuring the integrity and durability of the structure, so it is widely adopted.

[0003] In recent years, with the rapid development of infrastructure construction in China, the number of long-span concrete-filled steel tube arch bridges under construction has been increasing. However, the self-compacting concrete in the tube of long-span concrete-filled steel tube arch bridges has a large volume, high strength, long pumping distance and long pouring time, and it is easy to cause accidents such as pipe blockage and pipe explosion due to the increase in pumping resistance.

[0004] Chinese Patent Invention No. CN114542411A discloses a pumping system for double-pump pipeline infusion based on big data. The system is provided with pressure and speed sensors at the inlets and outlets of each pressurization component to monitor data in real time and feedback to adjust the rotation speed of each pressurization component. However, the length of the conveying pipe between the pressurization devices of the system and the pressure values required to be compensated by each level of pressurization device highly depend on the accurate calculation of the pressure loss of the concrete in this section of the pipeline. If the calculation of the pressure loss is incorrect, it may cause the compensated pressure to be too large or insufficient. Moreover, during the long-term pumping process, the rheological parameters of self-compacting concrete will change significantly, thereby affecting the result of the pumping pressure. Summary of the Invention

[0005] In view of this, the present invention proposes a method for calculating the pumping resistance of self-compacting concrete to solve the defect in the prior art that the rheological parameters of self-compacting concrete are not considered to change, and improve the calculation accuracy of the total pumping resistance in the pumping process of the pumping pipeline through the dynamic rheological characteristics of concrete, the environmental temperature and humidity effect, the pipeline geometric parameters and the pumping process parameters.

[0006] The technical solution of the present invention is realized as follows: The present invention provides a method for calculating the pumping resistance of self-compacting concrete, including the following steps: S1. Establish an initial pumping parameter model according to the pipeline geometric parameters of the pumping pipeline, the initial physical properties of self-compacting concrete, and the pumping process parameters; S2. Collect the pumping condition data in real time and perform digital filtering on the concrete flow rate in the pumping condition data to obtain the filtered concrete flow rate. The pumping condition data includes pumping time, pumping ambient temperature, relative humidity, and the concrete flow rate in the pumping pipeline. S3. According to the pumping time, pumping ambient temperature, and relative humidity, use the dynamic rheological evolution model to calculate the dynamic plastic viscosity of the self-compacting concrete under the current condition. S4. According to the initial pumping parameter model, dynamic plastic viscosity, and filtered concrete flow rate, calculate the pressure losses in different sections of the pumping pipeline, and obtain the total pumping resistance based on the pressure losses in each section.

[0007] On the basis of the above technical solutions, preferably, the pipeline geometric parameters of the pumping pipeline include the inner diameters of different pump pipes, the lengths of each horizontal pump pipe, and the vertical pumping height. The initial physical properties of the self-compacting concrete include the density of the self-compacting concrete, the initial plastic viscosity, the slump, the spread, the initial setting time, the final setting time, and the pouring time. The pumping process parameters include the flow rate of the concrete pump, the time for the piston to push the concrete, and the switching time of the distribution valve of the concrete pump.

[0008] On the basis of the above technical solutions, preferably, the dynamic rheological evolution model includes a basic evolution function, a temperature effect model, a humidity effect model, and a model parameter set. Step S3 specifically includes: Using the temperature effect model and the humidity effect model, according to the pumping ambient temperature and relative humidity, and combining with the model parameter set, calculate the comprehensive temperature and humidity correction factor of the plastic viscosity. Substitute the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor. Perform operations on the initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor to obtain the dynamic plastic viscosity of the self-compacting concrete under the current condition.

[0009] On the basis of the above technical solutions, preferably, the model parameter set includes a reference viscosity coefficient, an influence coefficient of spread, an influence coefficient of slump, a temperature sensitivity parameter of plastic viscosity, a reference temperature, a sensitivity index of plastic viscosity to humidity, a plastic viscosity growth coefficient, a rheological time evolution index, a reference flow resistance factor, an influence coefficient of spread on the flow resistance factor, and an influence coefficient of slump on the flow resistance factor.

[0010] On the basis of the above technical solutions, preferably, the calculation formula for the dynamic plastic viscosity of the self-compacting concrete under the current condition is: Wherein, It represents the dynamic plastic viscosity value of self-compacting concrete at any time t during the pumping process, under the conditions of pumping ambient temperature T and relative humidity RH. It represents the time elapsed since pumping started. It represents the initial plastic viscosity. It represents the reference viscosity coefficient. It represents the slump flow influence coefficient. It represents the slump influence coefficient. It represents the slump flow. It represents the slump. It represents the time correction factor. It represents the final setting time of the concrete. It represents the initial setting time of the concrete. It represents the comprehensive temperature and humidity correction factor for plastic viscosity. It represents the temperature sensitivity parameter of plastic viscosity. It represents the reference temperature. It represents the actual average temperature of the concrete. It represents the sensitivity index of plastic viscosity to humidity, and n represents the rheological time evolution index. It represents the plastic viscosity growth coefficient.

[0011] Based on the above technical solutions, preferably, the pumping pipeline includes a small-diameter pump pipe section and a large-diameter pump pipe section, where the diameter of the small-diameter pump pipe is not greater than 150 mm, and the diameter of the large-diameter pump pipe is not less than 600 mm.

[0012] Based on the above technical solutions, preferably, step S4 specifically includes: Calculating the dynamic adhesion coefficient using the dynamic plastic viscosity, calculating the dynamic velocity coefficient using the filtered concrete flow rate, and calculating the dynamic pressure loss of the small-diameter pump pipe section in combination with the pipeline geometric parameters and pumping process parameters; Calculating the pressure loss of the large-diameter pump pipe section using the self-compacting concrete density and the vertical pumping height of the large-diameter pump pipe section, calculating the pressure loss correction term of the large-diameter pump pipe section based on the friction and viscosity of the large-diameter pump pipe section, and obtaining the total dynamic pressure loss of the large-diameter pump pipe section based on the pressure loss and the pressure loss correction term; Determining the local loss of the pumping pipeline and the loss of the pump itself according to the initial pumping parameter model; Obtaining the total pumping resistance based on the dynamic pressure loss of the small-diameter pump pipe section, the total dynamic pressure loss of the large-diameter pump pipe section, the local loss, and the loss of the pump itself.

[0013] Based on the above technical solutions, preferably, the calculation formula for the dynamic pressure loss of the small-diameter pump pipe section is: Among them, represents the dynamic pressure loss of the small-diameter pump pipe section, represents the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic velocity coefficient, represents the time for the piston to push the concrete, represents the switching time of the distribution valve of the concrete pump, represents the ratio of the radial pressure to the axial pressure of the pumped concrete, represents the proportionality coefficient of the adhesion coefficient, represents the dynamic plastic viscosity value of the self-compacting concrete at any time t, pumping ambient temperature T, and relative humidity RH during the pumping process, represents the constant correction term of the adhesion coefficient, represents the influence factor of the flow velocity on the velocity coefficient, represents the average flow velocity of the concrete in the small-diameter pump pipe section, represents the adjustment constant of the velocity coefficient, represents the length of the small-diameter pump pipe section.

[0014] On the basis of the above technical solutions, preferably, the calculation formula for the total dynamic pressure loss of the large-diameter pump pipe section is: Among them, represents the pressure loss of the large-diameter pump pipe section, represents the comprehensive correction coefficient of the pipe diameter amplification and the gravity effect, represents the density of the self-compacting concrete, represents the acceleration due to gravity, represents the vertical pumping height of the large-diameter pump pipe section, represents the pressure loss correction term of the large-diameter pump pipe section, represents the adjustment coefficient of the friction viscosity term, represents the reference flow resistance factor, represents the influence coefficient of the spread on the flow resistance factor, represents the influence coefficient of the slump on the flow resistance factor, represents the length of the large-diameter pump pipe section, represents the inner diameter of the large-diameter pump pipe section, represents the average flow velocity of the concrete in the large-diameter pump pipe section, represents the dynamic pressure loss of the large-diameter pump pipe section.

[0015] Even more preferably, the pumping resistance calculation method further includes: Set a pumping safety factor; Calculate the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance; Compare the pumping pressure requirement of the pumping pipeline with the rated pumping resistance of the pump, and adjust the parameters of the pumping equipment.

[0016] The pumping resistance calculation method of self-compacting concrete of the present invention has the following beneficial effects compared with the prior art: (1) By means of the dynamic rheological properties of concrete, the environmental temperature and humidity effects, the pipeline geometric parameters and the pumping process parameters, the calculation accuracy of the total pumping resistance of the pumping pipeline during the pumping process is improved, the engineering risk is effectively reduced, and the safety of pumping construction is enhanced; (2) The viscosity change law of self-compacting concrete from the initial stage to before final setting is accurately described by the time correction factor, and the temperature influence factor and the humidity influence factor are introduced to quantify the influence of environmental conditions on the material properties, so as to improve the calculation accuracy of the pumping resistance; (3) By adopting the method of separately calculating the small-diameter pump pipe section and the large-diameter pump pipe section, the calculation accuracy of the pressure loss of the pumping pipeline is significantly improved. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a flowchart of the pumping resistance calculation method of self-compacting concrete of the present invention; Figure 2 It is a block diagram of the pumping resistance calculation method of self-compacting concrete of the present invention. Detailed Embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0020] As Figure 1 and Figure 2 shown, the present invention provides a pumping resistance calculation method for self-compacting concrete, including the following steps: S1. Establish an initial pumping parameter model based on the pipeline geometric parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters. Among them, the pipeline geometric parameters of the pumping pipeline include the inner diameters of different pump pipes, the lengths of each horizontal pump pipe, and the vertical pumping height. The initial physical properties of the self-compacting concrete include the self-compacting concrete density, the initial plastic viscosity, the slump, the spread, the initial setting time, and the final setting time. The pumping process parameters include the flow rate of the concrete pump, the time for the piston to push the concrete, and the switching time of the distribution valve of the concrete pump.

[0021] It can be understood that the initial physical properties of the self-compacting concrete are obtained through standard tests on the concrete mixture in the laboratory. For example, the concrete density is usually determined in the concrete mix design stage and rechecked by on-site sampling. The initial plastic viscosity is determined by rheological tests on self-compacting concrete samples through a rotational rheometer (such as a Brookfield viscometer, a coaxial cylinder rheometer, a vane rheometer, etc.) before the start of concrete pumping. By measuring the shear stress at different shear rates, a rheological curve is plotted, and then a suitable rheological model (such as the Bingham model, the Herschel-Bulkley model) is selected to fit the curve, so as to obtain the initial plastic viscosity.

[0022] S2. Real-time collect the pumping condition data and perform digital filtering processing on the concrete flow rate in the pumping condition data to obtain the filtered concrete flow rate. Among them, the pumping condition data includes the pumping time, the pumping ambient temperature, the relative humidity, and the concrete flow rate in the pumping pipeline. In an embodiment of the present invention, flow rate sensors are installed at the outlet of the pumping pipeline and the inlet and / or outlet positions of the large-diameter pump pipe section to obtain the flow rate of the concrete in the pumping pipeline.

[0023] In an embodiment of the present invention, temperature sensors are arranged at the starting point of the pumping pipeline (such as the discharge port of the mixing plant or the hopper of the pump), along the pumping pipeline (such as every 50 meters), and at the end point of the pumping pipeline (such as near the pouring port) to obtain the temperature and relative humidity data of the ambient air.

[0024] In an embodiment of the present invention, after collecting the pumping condition data, the pumping condition data is converted into engineering unit data with clear physical meanings. For example, the voltage signal is converted into a flow rate value in meters per second (m / s), a temperature value in degrees Celsius (°C), and a relative humidity value in percentage (%RH).

[0025] In an embodiment of the present invention, the median filtering method is used to process the pumping condition data, which specifically includes: Represent the data sequence of the concrete flow rate as x[n]; Select a neighborhood window according to the pumping condition data, where the size of the neighborhood window is N. By calculating the median value of the data points x[n-(N-1) / 2] to x[n+(N-1) / 2] within the window, the data sequence y[n] of the filtered concrete flow velocity after the wave is obtained.

[0026] Among them, the selection of the neighborhood window size N can be adjusted according to the noise level of the actual signal and the desired smoothness. Usually, when the sampling frequency of the sensor data is high, the selectable window size N can also be increased accordingly.

[0027] Specifically, a specific embodiment is used for illustration: When the window size N is set to 5, the filtered data point y[n] is the original data point The median value after sorting these five values.

[0028] S3. According to the pumping time, pumping ambient temperature and relative humidity, use the dynamic rheological evolution model to calculate the dynamic plastic viscosity of the self-compacting concrete under the current working condition.

[0029] In an embodiment of the present invention, the dynamic rheological evolution model includes a basic evolution function, a temperature effect model, a humidity effect model and a model parameter set. Step S3 specifically includes: Using the temperature effect model and the humidity effect model, according to the pumping ambient temperature and relative humidity, and combining the model parameter set to calculate the comprehensive temperature and humidity correction factor of the plastic viscosity; Substitute the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor; Perform operations on the initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor to obtain the dynamic plastic viscosity of the self-compacting concrete under the current working condition.

[0030] Among them, the model parameter set includes a reference viscosity coefficient, a slump spread influence coefficient, a slump influence coefficient, a temperature sensitivity parameter of the plastic viscosity, a reference temperature, a humidity sensitivity index of the plastic viscosity, a plastic viscosity growth coefficient, a rheological time evolution index, a reference flow resistance factor, an influence coefficient of the slump spread on the flow resistance factor, and an influence coefficient of the slump on the flow resistance factor.

[0031] It is understandable that both the temperature effect model and the humidity effect model are determined by using the non-linear regression analysis method. Among them, the temperature effect model is obtained by measuring the change of the rheological parameters of concrete with time under different temperature conditions, and the humidity effect model is obtained by measuring the rheological parameters of concrete under the same temperature but different humidity conditions. In self-compacting concrete, the plastic viscosity is a key rheological parameter that describes the flow behavior of concrete, which reflects the frictional characteristics of the fluid internal resistance to deformation and flow. The higher the plastic viscosity of the concrete, the more "viscous" it appears during flow, and the slower the flow rate under the same pumping pressure, or in other words, a greater pumping pressure is required to achieve the same flow rate.

[0032] By introducing the plastic viscosity that dynamically changes with the pumping time, ambient temperature and humidity, the real rheological state of concrete at a specific moment in the actual pumping path can be more realistically reflected.

[0033] Specifically, the calculation formula for the dynamic plastic viscosity of self-compacting concrete under the current working conditions is: Where, represents the value of the dynamic plastic viscosity of self-compacting concrete at any moment t during the pumping process, under the conditions of the pumping ambient temperature T and relative humidity RH, represents the time that the pumping has been carried out, represents the initial plastic viscosity, represents the reference viscosity coefficient, represents the slump flow influence coefficient, represents the slump influence coefficient, represents the slump flow, represents the slump, represents the time correction factor, represents the final setting time of the concrete, represents the initial setting time of the concrete, represents the comprehensive temperature and humidity correction factor of the plastic viscosity, represents the temperature sensitivity parameter of the plastic viscosity, represents the reference temperature, represents the actual average temperature of the concrete, represents the sensitivity index of the plastic viscosity to humidity, n represents the rheological time evolution index, represents the plastic viscosity growth coefficient.

[0034] It is understandable that during the pumping process of self-compacting concrete, due to the continuous progress of cement hydration, its rheological properties (especially plastic viscosity) will change continuously over time (usually increase). The environmental temperature and humidity during pumping are the most important external factors that affect the hydration rate of concrete and thus change the evolution rate of its rheological properties. The temperature sensitivity parameter of plastic viscosity is determined by fitting the change of plastic viscosity over time at different temperatures, which reflects the influence amplitude of temperature change on the plastic viscosity correction factor.

[0035] Among them, the slump flow is negatively correlated with the plastic viscosity, that is to say, more fluid concrete (high slump flow) usually has a lower plastic viscosity, while the slump is positively correlated with the plastic viscosity, reflecting the characteristics of self-compacting concrete: while maintaining high fluidity, its internal structure must have sufficient cohesiveness to prevent segregation.

[0036] The present invention accurately describes the viscosity change law of self-compacting concrete from the initial stage to before final setting through a time correction factor, and introduces a temperature influence factor and a humidity influence factor to quantify the influence of environmental conditions on material properties, improving the calculation accuracy of pumping resistance.

[0037] In an embodiment of the present invention, the dynamic rheological evolution model is a physical evolution model based on the Sigmoid growth curve and combined with temperature and humidity correction factors.

[0038] In an embodiment of the present invention, the reference viscosity coefficient usually ranges from The slump flow influence coefficient is the influence degree of the slump flow on the initial plastic viscosity (when the slump flow increases, the plastic viscosity decreases), usually in the range of 0.1 - 1.0 Pa·s / mm, and the slump influence coefficient is the influence degree of the slump on the initial plastic viscosity (when the slump increases, the plastic viscosity increases), usually in the range of 0.5 - 3.0 Pa·s / mm.

[0039] S4. Calculate the pressure losses in different sections of the pumping pipeline according to the initial pumping parameter model, the dynamic plastic viscosity, and the filtered concrete flow rate, and obtain the total pumping resistance based on the pressure losses in each section.

[0040] It is understandable that the sum of the pressure losses in each section is the total pumping resistance that the pumping equipment needs to overcome.

[0041] Specifically, the pumping pipeline includes a small-diameter pump pipe section and a large-diameter pump pipe section, where the diameter of the small-diameter pump pipe is not greater than 150 mm, and the diameter of the large-diameter pump pipe is not less than 600 mm.

[0042] Furthermore, step S4 specifically includes: Calculate the dynamic adhesion coefficient using the dynamic plastic viscosity, calculate the dynamic velocity coefficient using the filtered concrete flow velocity, and calculate the dynamic pressure loss in the small-diameter pump pipe section in combination with the pipe geometric parameters and pumping process parameters; the calculation formula for the dynamic pressure loss in the small-diameter pump pipe section is: Where, represents the dynamic pressure loss in the small-diameter pump pipe section, represents the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic velocity coefficient, represents the time for the piston to push the concrete, represents the switching time of the distribution valve of the concrete pump, represents the ratio of the radial pressure to the axial pressure of the pumped concrete, represents the proportionality coefficient of the adhesion coefficient, represents the value of the dynamic plastic viscosity of the self-compacting concrete at any time t, pumping ambient temperature T, and relative humidity RH during the pumping process, represents the constant correction term of the adhesion coefficient, represents the influence factor of the flow velocity on the velocity coefficient, represents the average flow velocity of the concrete in the small-diameter pump pipe section, represents the adjustment constant of the velocity coefficient, represents the length of the small-diameter pump pipe section.

[0043] Calculate the pressure loss in the large-diameter pump pipe section using the density of the self-compacting concrete and the vertical pumping height of the large-diameter pump pipe section, calculate the pressure loss correction term in the large-diameter pump pipe section based on the friction and viscosity in the large-diameter pump pipe section, and obtain the total dynamic pressure loss in the large-diameter pump pipe section based on the pressure loss and the pressure loss correction term; the calculation formula for the total dynamic pressure loss in the large-diameter pump pipe section is: Where, represents the pressure loss in the large-diameter pump pipe section, represents the comprehensive correction coefficient of the pipe diameter amplification and the gravity effect, represents the density of the self-compacting concrete, represents the acceleration due to gravity, represents the vertical pumping height of the large-diameter pump pipe section, represents the pressure loss correction term in the large-diameter pump pipe section, represents the adjustment coefficient of the friction viscosity term, represents the reference flow resistance factor, represents the influence coefficient of the slump on the flow resistance factor, Represents the influence coefficient of slump on the flow resistance factor, Represents the length of the large-diameter pump pipe section, Represents the inner diameter of the large-diameter pump pipe section, Represents the average flow velocity of the concrete in the large-diameter pump pipe section, Represents the dynamic pressure loss of the large-diameter pump pipe section; Determine the local loss of the pumping pipeline and the loss of the pump itself according to the initial pumping parameter model; Based on the dynamic pressure loss of the small-diameter pump pipe section, the total dynamic pressure loss of the large-diameter pump pipe section, the local loss and the loss of the pump itself, obtain the total pumping resistance; the calculation formula of the total pumping resistance is: Among them, Represents the total pumping resistance, Represents the local loss, Represents the hydraulic loss of the pump itself, Represents the local resistance coefficient, Represents the average flow velocity of the concrete at the local component, Represents the density of self-compacting concrete.

[0044] It can be understood that the dynamic pressure loss of the small-diameter pump pipe section = the comprehensive resistance effect term per unit length × the length of the small-diameter pump pipe section, where the dynamic adhesion coefficient Describes the resistance generated by the adhesion and friction between the concrete and the inner wall of the pump pipe. The dynamic plastic viscosity of the concrete Is the key factor affecting the adhesion effect. The dynamic velocity coefficient Describes the energy dissipation generated by the relative movement and flow velocity inside the concrete, that is, the viscous resistance. During the actual pumping process, The larger the ratio of, the greater the velocity-related pressure loss.

[0045] Reference flow resistance factor Represents the basic value of the internal flow resistance of self-compacting concrete with a standard mix ratio under reference conditions. Usually, a pressure sensor is used to measure the pressure drop along the way and determined through regression analysis; the influence coefficient of the spread on the flow resistance factor Quantifies the adjustment effect of the concrete spread performance on the flow resistance, that is, the increase in the spread indicates the improvement of the overall fluidity of the concrete, so the flow resistance decreases, Determined through multiple linear regression analysis; the influence coefficient of slump on the flow resistance factor Characterizes the influence degree of the concrete slump on the flow resistance. Among them, the slump is measured by the multi-ratio comparison test method, the pressure loss is measured, and then obtained through statistical regression analysis .

[0046] The initial pumping parameter model includes a local loss module, in which the local resistance coefficients ( values) of concrete flowing through various non-linear components in the pumping pipeline (such as elbows (bends), reducers (enlarging or reducing sections), tees, valves, inlets and outlets, etc.) are pre-stored. After determining the set parameters of the pumping pipeline, these local resistance elements and their quantities are identified according to the pipeline configuration, and the corresponding values are retrieved from the model. The local loss can be calculated based on the hydrodynamic dynamic pressure loss formula.

[0047] The initial pumping parameter model also includes data on the performance of the concrete pump used, and the hydraulic loss of the pump itself is determined by specific values obtained through calibration experiments under specific working conditions and preset in this model.

[0048] The present invention significantly improves the calculation accuracy of the pressure loss of the pumping pipeline by adopting the method of separate calculation for the small-diameter pump pipe section and the large-diameter pump pipe section.

[0049] In an embodiment of the present invention, by installing a flow velocity sensor at a key position of the pumping pipeline (such as the pump outlet or the main delivery pipe), the concrete pump flow rate is measured, and the average flow velocity of the concrete in the small-diameter pump pipe section and the average flow velocity of the concrete in the large-diameter pump pipe section are calculated respectively: : wherein, represents the cross-sectional area of the small-diameter pump pipe section, represents the inner diameter of the small-diameter pump pipe section, represents the cross-sectional area of the large-diameter pump pipe section, represents the inner diameter of the large-diameter pump pipe section.

[0050] The present invention improves the calculation accuracy of the total pumping resistance of the pumping pipeline during the pumping process through the dynamic rheological characteristics of concrete, the environmental temperature and humidity effects, the pipeline geometric parameters and the pumping process parameters, effectively reduces the engineering risk, and improves the safety of the pumping construction.

[0051] In an embodiment of the present invention, independent flow velocity sensors are respectively arranged in the small-diameter pump pipe section and the large-diameter pump pipe section, and the average flow velocity of the concrete in the small-diameter pump pipe section and the average flow velocity of the concrete in the large-diameter pump pipe section can directly adopt the readings after filtering by the flow velocity sensor.

[0052] In an embodiment of the present invention, when the diameter of the large-diameter pump pipe section is 600 mm, take 1.00, and when the pipe diameter is 1500 mm, take 1.09, and the intermediate pipe diameters are calculated using linear interpolation value.

[0053] In an embodiment of the present invention, when the ratio of the switching time of the concrete pump distribution valve to the time for the piston to push the concrete is 0.3, and the ratio of the radial pressure to the axial pressure of the pumped concrete is 0.9, a total of 7 groups of calculated values and test values for the actual bridge pouring are compared, and the results are shown in Table 1: As can be seen from Table 1, the deviation rate between the calculated value and the test value ≤ -3.37%, that is, the calculation result is in good agreement with the test result, indicating that it is feasible to calculate the pumping pressure of the concrete in the pump pipe using the above formula.

[0054] In an embodiment of the present invention, for the actual bridge pouring of the large-diameter pump pipe section, a total of 9 groups of pressure loss values of the large-diameter pump pipe section are compared with the test values, and the results are shown in Table 2: Table 2 Comparison table of measured and calculated values of concrete pumping pressure in steel pipe As can be seen from Table 2, the deviation rate between the pressure loss value of the large-diameter pump pipe section and the test value ≤ 9.77%, that is, the pressure loss result of the large-diameter pump pipe section is in good agreement with the test result, indicating that the calculation formula for the pressure loss of the large-diameter pump pipe section can be used to guide the calculation of the pumping pressure of the concrete in the main arch steel pipe.

[0055] Furthermore, the pumping resistance calculation method further includes: setting a pumping safety factor; calculating the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance; comparing the pumping pressure requirement of the pumping pipeline with the rated pumping resistance of the pump machine, and adjusting the pumping equipment parameters.

[0056] A specific embodiment is used to specifically illustrate the pumping resistance calculation method for self-compacting concrete: Prepare the concrete in the pipe using the dense skeleton theory. Through carrying out relevant tests on the working performance of the concrete, the performance of the concrete should meet the requirements of the pumpability index of the main pipe concrete of the concrete-filled steel tube arch bridge. As shown in Table 3, the volume stability of the main pipe concrete of the concrete-filled steel tube arch bridge is: in a closed environment, the free expansion rate of the concrete should be controlled within 1×10 -4 ~6×10 -4, the stable convergence period should be less than 60 days, and the gas content is: the gas content of the concrete in the steel pipe should not be greater than 2.5%: Among them, the perfusion time refers to the time from the concrete leaving the mixing plant to the completion of the perfusion of a single main pipe; Calculate the dynamic plastic viscosity based on the initial plastic viscosity of the concrete tested in the concrete test, and calculate the viscosity coefficient; Determine the pumping speed according to the construction organization arrangement of the pumping perfusion, and calculate the speed coefficient; Calculate the frictional resistance of the concrete pumping pressure in the horizontal pump pipe based on the dynamic plastic viscosity, viscosity coefficient and speed coefficient, and convert it into the horizontal pump pipe layout length L according to the actual layout of the on-site pump pipe to obtain the pumping resistance of the concrete in the small-diameter pump pipe section; Calculate the pumping pressure required for the concrete to move in the main arch steel pipe according to the rise of the concrete-filled steel tube arch bridge; Determine the total pumping resistance according to the dynamic pressure loss in the small-diameter pump pipe section, the total dynamic pressure loss in the large-diameter pump pipe section, the local loss and the loss of the pump itself, and determine the power of the pump, the wall thickness of the pump pipe and the specification of the pump pipe clamp based on the total pumping resistance; Verify whether the maximum pumping resistance of the pump can meet the actual pumping requirements. It should be satisfied that: the total pumping resistance P required for concrete pumping × 1.5 ≤ the maximum pumping resistance of the pump (taking a safety factor of 1.5). If not satisfied, a pump with a larger power should be replaced, or the plastic viscosity of the concrete should be reduced, or the pumping speed should be reduced, or the diameter of the pump pipe should be increased.

[0057] Compare the calculated formula for the pumping resistance of the concrete in the small-diameter pump pipe section proposed by the test with the measured value of the pumping pressure of the actual bridge. Among them, the calculated value and the measured value of the frictional resistance of the horizontal pump pipe are in the unit of pressure gradient, that is, the pressure loss per unit length. The comparison results are shown in Table 4 below: It can be seen from the above table that the calculated value of the pumping pressure of the horizontal pump pipe proposed in this test is in good agreement with the measured value of the test. Through this correction calculation method, the pumping pressure value of the concrete in the horizontal pump pipe can be calculated more accurately, providing guidance for engineering practice.

[0058] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating the pumping resistance of self-compacting concrete, characterized in that: It includes the following steps: S1. Establish an initial pumping parameter model according to the pipe geometric parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters; S2. Collect the pumping condition data in real time and perform digital filtering on the concrete flow rate in the pumping condition data to obtain the filtered concrete flow rate; wherein the pumping condition data includes pumping time, pumping ambient temperature, relative humidity, and the concrete flow rate in the pumping pipeline; S3. Calculate the dynamic plastic viscosity of the self-compacting concrete under the current condition by using the dynamic rheological evolution model according to the pumping time, pumping ambient temperature, and relative humidity; S4. Calculate the pressure losses in different sections of the pumping pipeline according to the initial pumping parameter model, the dynamic plastic viscosity, and the filtered concrete flow rate, and obtain the total pumping resistance based on the pressure losses in each section.

2. The pumping resistance calculation method of self-compacting concrete according to claim 1, characterized in that: The pipe geometric parameters of the pumping pipeline include the inner diameters of different pump pipes, the lengths of each horizontal pump pipe, and the vertical pumping height. The initial physical properties of the self-compacting concrete include the self-compacting concrete density, initial plastic viscosity, slump, spread, initial setting time, final setting time, and pouring time. The pumping process parameters include the concrete pump flow rate, the piston pushing time of the concrete, and the concrete pump distribution valve switching time.

3. The pumping resistance calculation method of self-compacting concrete according to claim 2, characterized in that: The dynamic rheological evolution model includes a basic evolution function, a temperature effect model, a humidity effect model, and a model parameter set. Step S3 specifically includes: Using the temperature effect model and the humidity effect model, calculate the comprehensive temperature and humidity correction factor of the plastic viscosity according to the pumping ambient temperature and relative humidity, and in combination with the model parameter set; Substitute the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor; Perform operations on the initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor to obtain the dynamic plastic viscosity of the self-compacting concrete under the current condition.

4. The pumping resistance calculation method of a self-compacting concrete according to claim 3, characterized in that: The model parameter set includes a reference viscosity coefficient, a spread influence coefficient, a slump influence coefficient, a temperature sensitivity parameter of the plastic viscosity, a reference temperature, a humidity sensitivity index of the plastic viscosity, a plastic viscosity growth coefficient, a rheological time evolution index, a reference flow resistance factor, an influence coefficient of the spread on the flow resistance factor, and an influence coefficient of the slump on the flow resistance factor.

5. The pumping resistance calculation method of a self-compacting concrete according to claim 4, characterized in that: The calculation formula for the dynamic plastic viscosity of the self-compacting concrete under the current condition is: Among them, represents the dynamic plastic viscosity value of self-compacting concrete at any time t during the pumping process, under the conditions of pumping ambient temperature T and relative humidity RH. represents the time elapsed since pumping started. represents the initial plastic viscosity. represents the reference viscosity coefficient. represents the slump flow influence coefficient. represents the slump influence coefficient. represents the slump flow. represents the slump. represents the time correction factor. represents the final setting time of the concrete. represents the initial setting time of the concrete. represents the comprehensive temperature and humidity correction factor of the plastic viscosity. represents the temperature sensitivity parameter of the plastic viscosity. represents the reference temperature. represents the actual average temperature of the concrete. represents the sensitivity index of the plastic viscosity to humidity, and n represents the rheological time evolution index. represents the plastic viscosity growth coefficient.

6. The pumping resistance calculation method of a self-compacting concrete according to claim 4, characterized in that: The pumping pipeline includes a small-diameter pump pipe section and a large-diameter pump pipe section, wherein the diameter of the small-diameter pump pipe is not greater than 150 mm, and the diameter of the large-diameter pump pipe is not less than 600 mm.

7. The pumping resistance calculation method of self-compacting concrete according to claim 6, characterized in that: Step S4 specifically includes: Calculate the dynamic adhesion coefficient by using the dynamic plastic viscosity, calculate the dynamic velocity coefficient by using the filtered concrete flow rate, and calculate the dynamic pressure loss in the small-diameter pump pipe section in combination with the pipe geometric parameters and the pumping process parameters; Calculate the pressure loss in the large-diameter pump pipe section by using the self-compacting concrete density and the vertical pumping height of the large-diameter pump pipe section, calculate the pressure loss correction term in the large-diameter pump pipe section based on the friction and viscosity in the large-diameter pump pipe section, and obtain the total dynamic pressure loss in the large-diameter pump pipe section based on the pressure loss and the pressure loss correction term. Determine the local loss of the pumping pipeline and the loss of the pump itself according to the initial pumping parameter model; Based on the dynamic pressure loss of the small-diameter pump pipe section, the total dynamic pressure loss of the large-diameter pump pipe section, the local loss, and the loss of the pump itself, obtain the total pumping resistance.

8. The pumping resistance calculation method of a self-compacting concrete according to claim 7, characterized in that: The calculation formula for the dynamic pressure loss of the small-diameter pump pipe section is: Among them, represents the dynamic pressure loss of the small-diameter pump pipe section, represents the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic velocity coefficient, represents the time for the piston to push the concrete, represents the switching time of the concrete pump distribution valve, represents the ratio of the radial pressure to the axial pressure of the pumped concrete, represents the proportionality coefficient of the adhesion coefficient, represents the dynamic plastic viscosity value of the self-compacting concrete at any time t, pumping ambient temperature T, and relative humidity RH during the pumping process, represents the constant correction term of the adhesion coefficient, represents the influence factor of the flow velocity on the velocity coefficient, represents the average flow velocity of the concrete in the small-diameter pump pipe section, represents the adjustment constant of the velocity coefficient, represents the length of the small-diameter pump pipe section.

9. The pumping resistance calculation method of a self-compacting concrete according to claim 8, characterized in that: The calculation formula for the total dynamic pressure loss of the large-diameter pump pipe section is: Among them, represents the pressure loss of the large-diameter pump pipe section, represents the comprehensive correction coefficient of pipe diameter enlargement and gravity effect, represents the density of self-compacting concrete, represents the acceleration due to gravity, represents the vertical pumping height of the large-diameter pump pipe section, represents the pressure loss correction term of the large-diameter pump pipe section, represents the adjustment coefficient of the frictional viscous term, represents the reference flow resistance factor, represents the influence coefficient of slump flow on the flow resistance factor, represents the influence coefficient of slump on the flow resistance factor, represents the length of the large-diameter pump pipe section, represents the inner diameter of the large-diameter pump pipe section, represents the average flow velocity of concrete in the large-diameter pump pipe section, represents the dynamic pressure loss of the large-diameter pump pipe section.

10. A method for calculating the pumping resistance of self-compacting concrete according to claim 1, characterized in that: The pumping resistance calculation method further includes: Set a pumping safety factor; Calculate the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance; Compare the pumping pressure requirement of the pumping pipeline with the rated pumping resistance of the pump, and adjust the pumping equipment parameters.

Images