A method for calculating pumping resistance of self-compacting concrete

Abstract

The present invention proposes a method for calculating the pumping resistance of self-compacting concrete, which belongs to the field of pumping. The method comprises: S1: establishing an initial pumping parameter model based on the geometric parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters; S2: real-time acquisition of pumping condition data and digital filtering to obtain the filtered concrete flow rate; S3: calculating the dynamic plastic viscosity of the self-compacting concrete under the current working conditions using a dynamic rheological evolution model based on the pumping time, pumping ambient temperature, and relative humidity; S4: calculating the pressure loss in different sections of the pumping pipeline based on the initial pumping parameter model, the dynamic plastic viscosity, and the filtered concrete flow rate, and obtaining the total pumping resistance based on the pressure loss in each section. The present invention improves the accuracy of calculating the total pumping resistance of the pumping pipeline by taking into account the dynamic rheological properties of concrete, the effects of ambient temperature and humidity, the geometric parameters of the pipeline, and the pumping process parameters.

Description

Technical Field

[0001] The present invention relates to the field of pumping technology, 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 (SCC) boasts excellent fluidity, filling properties, economy, and environmental friendliness, making it widely used in large bridges, high-rise buildings, and water conservancy projects. In particular, it is widely adopted in the construction of long-span concrete-filled steel tubular arch bridges due to its excellent fluidity and self-compacting properties, enabling it to effectively fill densely packed steel bars and complex cross-sections, ensuring structural integrity and durability.

[0003] In recent years, with the rapid development of infrastructure construction in my country, the number of long-span steel tube concrete arch bridges has continued to increase. However, the large volume and high strength of the self-compacting concrete in these large-span steel tube concrete arch bridges require long pumping distances and long pouring times, making them prone to accidents such as pipe blockage and bursts due to increased pumping resistance.

[0004] Chinese invention patent publication number CN114542411A discloses a dual-pump pipeline infusion pumping system based on big data. This system uses pressure and speed sensors installed at the inlet and outlet of each booster assembly to monitor data in real time and use feedback to adjust the speed of each booster assembly. However, the length of the delivery pipe between the booster units in this system, as well as the pressure compensation required by each booster unit, are highly dependent on the accurate calculation of the pressure loss of concrete within that section of the pipeline. Incorrect calculations of the pressure loss can result in excessive or insufficient compensation pressure. Furthermore, over long periods of pumping, the rheological parameters of the self-compacting concrete can change significantly, affecting the resulting 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 have not changed. By taking into account the dynamic rheological characteristics 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.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a method for calculating the pumping resistance of self-compacting concrete, comprising the following steps:

[0007] S1. Establishing an initial pumping parameter model based on the geometric parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters;

[0008] S2. Real-time collection of pumping condition data and digital filtering of the concrete flow rate in the pumping condition data to obtain a filtered concrete flow rate, wherein the pumping condition data includes pumping time, pumping ambient temperature, relative humidity, and concrete flow rate in the pumping pipeline;

[0009] S3. Calculating the dynamic plastic viscosity of the self-compacting concrete under the current working conditions using a dynamic rheological evolution model based on the pumping time, pumping ambient temperature, and relative humidity;

[0010] S4. Calculate the pressure loss of 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 a total pumping resistance based on the pressure loss of each section.

[0011] On the basis of the above technical solution, 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 expansion, 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 concrete pump distribution valve.

[0012] On the basis of the above technical solution, preferably, the dynamic rheological evolution model includes a basic evolution function, a temperature effect model, a humidity effect model and a model parameter set, and step S3 specifically includes:

[0013] The temperature effect model and the humidity effect model are used to calculate the comprehensive temperature and humidity correction factor of the plastic viscosity according to the pumping environment temperature and relative humidity and in combination with the model parameter set;

[0014] Substituting the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor;

[0015] The initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor are calculated to obtain the dynamic plastic viscosity of the self-compacting concrete under the current working conditions.

[0016] Based on the above technical solution, preferably, the model parameter set includes a baseline viscosity coefficient, an expansion influence coefficient, a slump influence coefficient, 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 baseline flow resistance factor, an influence coefficient of expansion on the flow resistance factor, and an influence coefficient of slump on the flow resistance factor.

[0017] On the basis of the above technical solution, preferably, the calculation formula of the dynamic plastic viscosity of the self-compacting concrete under the current working conditions is:

[0018]

[0019] in, It represents the dynamic plastic viscosity of self-compacting concrete at any time t during the pumping process, under the conditions of pumping ambient temperature T and relative humidity RH. Indicates the time the pumping has been running, represents the initial plastic viscosity, represents the base viscosity coefficient, represents the expansion influence coefficient, represents the slump influence coefficient, Indicates the degree of expansion, Indicates slump, represents the time correction factor, The final setting time of concrete. Indicates the initial setting time of concrete. Indicates the comprehensive temperature and humidity correction factor for plastic viscosity, Parameter representing the temperature sensitivity of plastic viscosity, represents the reference temperature, represents the actual average temperature of the concrete, represents the sensitivity index of plastic viscosity to humidity, n represents the rheological time evolution index, Represents the plastic viscosity growth coefficient.

[0020] On the basis of the above technical solution, preferably, 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.

[0021] Based on the above technical solution, preferably, step S4 specifically includes:

[0022] The dynamic plastic viscosity is used to calculate the dynamic adhesion coefficient, the filtered concrete flow velocity is used to calculate the dynamic velocity coefficient, and the dynamic pressure loss of the small diameter pump pipe section is calculated in combination with the pipeline geometric parameters and the pumping process parameters;

[0023] calculating the pressure loss of 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, calculating a pressure loss correction term for the large diameter pump pipe section based on friction and viscosity of the large diameter pump pipe section, and obtaining a total dynamic pressure loss of the large diameter pump pipe section based on the pressure loss and the pressure loss correction term;

[0024] Determining the local loss of the pumping pipeline and the loss of the pump itself according to the initial pumping parameter model;

[0025] The total pumping resistance is obtained 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 machine itself.

[0026] On the basis of the above technical solution, preferably, the calculation formula for the dynamic pressure loss of the small diameter pump pipe section is:

[0027] in, Indicates the dynamic pressure loss in the small diameter pump pipe section, Indicates the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic speed coefficient, Indicates the time it takes for the piston to push the concrete. Indicates the switching time of the concrete pump distribution valve, It represents the ratio of radial to axial pressure of pumped concrete. represents the proportionality coefficient of the adhesion coefficient, 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. represents the constant correction term of the adhesion coefficient, Indicates the influence factor of flow velocity on velocity coefficient, Indicates the average flow velocity of concrete in the small diameter pump pipe section, represents the adjustment constant of the speed coefficient, Indicates the length of the small diameter pump tubing section.

[0028] On the basis of the above technical solution, preferably, the calculation formula of the total dynamic pressure loss of the large-diameter pump pipe section is:

[0029] in, Indicates the pressure loss in the large diameter pump pipe section, Indicates the comprehensive correction coefficient of pipe diameter enlargement and gravity effect, represents the density of self-compacting concrete, represents the acceleration due to gravity, Indicates the vertical pumping height of the large diameter pump pipe section, represents the pressure loss correction term for the large diameter pump pipe section, represents the adjustment coefficient of the friction viscosity term, represents the base flow resistance factor, Indicates the influence coefficient of expansion on flow resistance factor, Indicates the influence coefficient of slump on flow resistance factor, Indicates the length of the large diameter pump pipe section, Indicates the inner diameter of the large diameter pump pipe section, Indicates the average flow velocity of concrete in the large diameter pump pipe section, Indicates the dynamic pressure loss in the large diameter pump pipe section.

[0030] More preferably, the pumping resistance calculation method further includes:

[0031] Set pumping safety factor;

[0032] Calculating the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance;

[0033] The pumping pressure requirement of the pumping pipeline is compared with the rated pumping resistance of the pump machine, and the pumping equipment parameters are adjusted.

[0034] The method for calculating the pumping resistance of self-compacting concrete of the present invention has the following beneficial effects compared with the prior art:

[0035] (1) By considering the dynamic rheological characteristics of concrete, the effects of ambient temperature and humidity, the geometric parameters of the pipeline, and the pumping process parameters, the accuracy of the calculation of the total pumping resistance of the pumping pipeline during the pumping process is improved, which effectively reduces the engineering risk and improves the safety of the pumping construction;

[0036] (2) The time correction factor is used to accurately describe the viscosity change of self-compacting concrete from the initial stage to the final setting stage. The temperature and humidity influence factors are introduced to quantify the influence of environmental conditions on material properties, thereby improving the accuracy of the calculation of pumping resistance.

[0037] (3) By adopting the method of separate calculation of small diameter pump pipe sections and large diameter pump pipe sections, the calculation accuracy of the pumping pipeline pressure loss is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 Flowchart of the method for calculating the pumping resistance of self-compacting concrete of the present invention;

[0040] Figure 2 It is a block diagram of the method for calculating the pumping resistance of self-compacting concrete according to the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] like Figure 1 and Figure 2 As shown, the present invention provides a method for calculating the pumping resistance of self-compacting concrete, comprising the following steps:

[0043] S1. Establishing an initial pumping parameter model based on the pipeline geometry parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters; wherein the pipeline geometry 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, initial plastic viscosity, slump, expansion, initial setting time and final setting time of the self-compacting concrete; and 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 concrete pump distribution valve.

[0044] As you can understand, the initial physical properties of self-compacting concrete are obtained through standard laboratory tests on concrete mixtures. For example, concrete density is typically determined during the concrete mix design phase and sampled on-site for verification. Initial plastic viscosity, on the other hand, is determined by rheological testing of self-compacting concrete samples using a rotational rheometer (such as a Brookfield viscometer, coaxial cylinder rheometer, or vane rheometer) before concrete pumping begins. The initial plastic viscosity is determined by measuring shear stress at different shear rates, plotting rheological curves, and then fitting the curves using an appropriate rheological model (such as the Bingham model or the Herschel-Bulkley model).

[0045] S2. Real-time collection of pumping condition data and digital filtering of the concrete flow rate in the pumping condition data to obtain a filtered concrete flow rate, wherein the pumping condition data includes pumping time, pumping ambient temperature, relative humidity, and concrete flow rate in the pumping pipeline;

[0046] In one embodiment of the present invention, flow rate sensors are installed at the outlet of the pumping pipeline and the inlet and / or outlet of the large-diameter pump pipe section to obtain the flow rate of concrete in the pumping pipeline.

[0047] In one embodiment of the present invention, temperature sensors are installed at the starting point of the pumping pipeline (such as the discharge port of the mixing station 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.

[0048] In one embodiment of the present invention, after collecting the pumping operating condition data, the pumping operating condition data is converted into engineering unit data with clear physical meaning, for example, the voltage signal is converted into a flow rate value in meters per second (m / s), or a temperature value in degrees Celsius (°C), and a relative humidity value in percentage (%RH).

[0049] In one embodiment of the present invention, the pumping condition data is processed using a median filtering method, specifically including:

[0050] The data sequence of the concrete flow rate is expressed as x[n];

[0051] A neighborhood window is selected according to the pumping condition data, where the neighborhood window size is N. By calculating the median of the data points x[n-(N-1) / 2] to x[n+(N-1) / 2] in the window, the filtered concrete flow rate data sequence y[n] is obtained.

[0052] The selection of the neighborhood window size N can be adjusted according to the noise level of the actual signal and the desired smoothness. Generally, when the sampling frequency of the sensor data is high, the selectable window size N can also be increased accordingly.

[0053] Specifically, a specific embodiment is used to illustrate:

[0054] When the window size N is set to 5, the filtered data point y[n] is the original data point The middle value of these five values ​​after sorting.

[0055] S3. According to the pumping time, pumping environment temperature and relative humidity, the dynamic plastic viscosity of the self-compacting concrete under the current working condition is calculated using a dynamic rheological evolution model.

[0056] In one 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:

[0057] The temperature effect model and the humidity effect model are used to calculate the comprehensive temperature and humidity correction factor of the plastic viscosity according to the pumping environment temperature and relative humidity and in combination with the model parameter set;

[0058] Substituting the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor;

[0059] The initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor are calculated to obtain the dynamic plastic viscosity of the self-compacting concrete under the current working conditions.

[0060] Among them, the model parameter set includes a baseline viscosity coefficient, an expansion influence coefficient, a slump influence coefficient, 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 baseline flow resistance factor, an influence coefficient of expansion on the flow resistance factor, and an influence coefficient of slump on the flow resistance factor.

[0061] It can be understood that both the temperature effect model and the humidity effect model are determined using nonlinear regression analysis. The temperature effect model is obtained based on the measurement of the changes in the rheological parameters of concrete over time under different temperature conditions, and the humidity effect model is obtained based on the measurement of the rheological parameters of concrete under the same temperature but different humidity conditions. In self-compacting concrete, plastic viscosity is a key rheological parameter that describes the flow behavior of concrete. It reflects the friction characteristics of the fluid's internal resistance to deformation and flow. The higher the plastic viscosity of the concrete, the more "viscous" it appears when flowing, and the slower the flow rate at the same pumping pressure, or in other words, a greater pumping pressure is required to achieve the same flow rate.

[0062] By introducing the plastic viscosity that changes dynamically with pumping time, ambient temperature and humidity, the actual rheological state of concrete at a specific moment in the actual pumping path can be more realistically reflected.

[0063] Specifically, the calculation formula for the dynamic plastic viscosity of the self-compacting concrete under the current working conditions is:

[0064]

[0065] in, It represents the dynamic plastic viscosity of self-compacting concrete at any time t during the pumping process, under the conditions of pumping ambient temperature T and relative humidity RH. Indicates the time the pumping has been running, represents the initial plastic viscosity, represents the base viscosity coefficient, represents the expansion influence coefficient, represents the slump influence coefficient, Indicates the degree of expansion, Indicates slump, represents the time correction factor, The final setting time of concrete. Indicates the initial setting time of concrete. Indicates the comprehensive temperature and humidity correction factor for plastic viscosity, Parameter representing the temperature sensitivity of plastic viscosity, represents the reference temperature, represents the actual average temperature of the concrete, represents the sensitivity index of plastic viscosity to humidity, n represents the rheological time evolution index, Represents the plastic viscosity growth coefficient.

[0066] As is understandable, during the pumping process, the rheological properties (particularly plastic viscosity) of self-compacting concrete (SCC) continuously change (typically increasing) over time due to the ongoing cement hydration process. The temperature and humidity of the pumping environment are the most important external factors affecting the hydration rate of concrete, and thus the rate at which its rheological properties evolve. The temperature sensitivity parameter for plastic viscosity is determined by fitting the change in plastic viscosity over time at different temperatures. It reflects the magnitude of the impact of temperature changes on the plastic viscosity correction factor.

[0067] Among them, the expansion is negatively correlated with the plastic viscosity, that is, more fluid concrete (high expansion) 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 cohesion to prevent segregation.

[0068] The present invention accurately describes the viscosity change law of self-compacting concrete from initial to final setting through a time correction factor, and introduces temperature and humidity influence factors to quantify the influence of environmental conditions on material properties, thereby improving the calculation accuracy of pumping resistance.

[0069] In one embodiment of the present invention, the dynamic rheological evolution model is a physical evolution model based on a Sigmoid growth curve and combined with temperature and humidity correction factors.

[0070] In one embodiment of the present invention, the reference viscosity coefficient Usually in The expansion coefficient The influence of expansion on initial plastic viscosity (expansion increases, plastic viscosity decreases), usually in the range of 0.1-1.0 Pa·s / mm, slump influence coefficient It is the degree of influence of slump on initial plastic viscosity (the increase of slump increases the plastic viscosity), usually in the range of 0.5-3.0 Pa·s / mm.

[0071] S4. Calculate the pressure loss of 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 a total pumping resistance based on the pressure loss of each section.

[0072] It can be understood that the sum of the pressure losses in each section is the total pumping resistance that the pumping equipment needs to overcome.

[0073] Specifically, 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.

[0074] Furthermore, step S4 specifically includes:

[0075] The dynamic plastic viscosity is used to calculate the dynamic adhesion coefficient, the filtered concrete flow velocity is used to calculate the dynamic velocity coefficient, and the dynamic pressure loss of the small diameter pump pipe section is calculated in combination with the pipeline geometric parameters and pumping process parameters. The calculation formula for the dynamic pressure loss of the small diameter pump pipe section is:

[0076]

[0077] in, Indicates the dynamic pressure loss in the small diameter pump pipe section, Indicates the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic speed coefficient, Indicates the time it takes for the piston to push the concrete. Indicates the switching time of the concrete pump distribution valve, It represents the ratio of radial to axial pressure of pumped concrete. represents the proportionality coefficient of the adhesion coefficient, 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. represents the constant correction term of the adhesion coefficient, Indicates the influence factor of flow velocity on velocity coefficient, Indicates the average flow velocity of concrete in the small diameter pump pipe section, represents the adjustment constant of the speed coefficient, Indicates the length of the small diameter pump tubing section.

[0078] The pressure loss of the large-diameter pump pipe section is calculated using the density of the self-compacting concrete and the vertical pumping height of the large-diameter pump pipe section. The pressure loss correction term of the large-diameter pump pipe section is calculated based on the friction and viscosity of the large-diameter pump pipe section. The total dynamic pressure loss of the large-diameter pump pipe section is obtained based on the pressure loss and the pressure loss correction term. The calculation formula for the total dynamic pressure loss of the large-diameter pump pipe section is:

[0079]

[0080] in, Indicates the pressure loss in the large diameter pump pipe section, Indicates the comprehensive correction coefficient of pipe diameter enlargement and gravity effect, represents the density of self-compacting concrete, represents the acceleration due to gravity, Indicates the vertical pumping height of the large diameter pump pipe section, represents the pressure loss correction term for the large diameter pump pipe section, represents the adjustment coefficient of the friction viscosity term, represents the base flow resistance factor, Indicates the influence coefficient of expansion on flow resistance factor, Indicates the influence coefficient of slump on flow resistance factor, Indicates the length of the large diameter pump pipe section, Indicates the inner diameter of the large diameter pump pipe section, Indicates the average flow velocity of concrete in the large diameter pump pipe section, Indicates the dynamic pressure loss in the large diameter pump pipe section;

[0081] Determining the local loss of the pumping pipeline and the loss of the pump itself according to the initial pumping parameter model;

[0082] The total pumping resistance is obtained 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. The calculation formula of the total pumping resistance is:

[0083]

[0084] in, Indicates the total pumping resistance, Indicates local loss, Indicates the hydraulic loss of the pump itself, represents the local resistance coefficient, represents the average concrete flow velocity at the local component, Indicates the density of self-compacting concrete.

[0085] It can be understood that the dynamic pressure loss of the small diameter pump pipe section = the comprehensive resistance effect per unit length × the length of the small diameter pump pipe section, where the dynamic viscosity coefficient is 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 It is the key factor affecting the adhesion effect, the dynamic speed coefficient Describes the energy dissipation caused by relative movement and flow velocity inside the concrete, namely viscous resistance. In the actual pumping process, The larger the ratio, the greater the velocity-related pressure loss.

[0086] Baseline flow resistance factor The basic value of the internal flow resistance of self-compacting concrete with a standard mix ratio under benchmark conditions is usually determined by measuring the pressure drop along the way using a pressure sensor and through regression analysis; the coefficient of influence of expansion on the flow resistance factor The regulatory effect of concrete expansion performance on flow resistance was quantified, that is, an increase in expansion indicates an increase in the overall fluidity of concrete, thus reducing the flow resistance. Determine the influence coefficient of slump on flow resistance factor through multiple linear regression analysis; The influence of concrete slump on flow resistance is characterized by the slump test method of multiple ratios, measuring the pressure loss, and then statistical regression analysis to obtain .

[0087] The initial pumping parameter model includes a local loss module, which pre-stores the local resistance coefficients of concrete flowing through various non-straight components in the pumping pipeline (such as elbows (bends), reducers (enlarged or reduced sections), tees, valves, inlets and outlets, etc.) After determining the collective parameters of the pumping pipeline, these local resistance elements and their quantities are identified according to the pipeline configuration, and the corresponding Value. Local loss It can be calculated based on the fluid mechanics dynamic pressure loss formula.

[0088] The initial pumping parameter model also includes data on the performance of the concrete pump used, the hydraulic losses of the pump itself The specific values ​​are determined by calibration experiments under specific working conditions and preset in the model.

[0089] The present invention significantly improves the calculation accuracy of the pumping pipeline pressure loss by adopting a method of separate calculation of the small-diameter pump pipe section and the large-diameter pump pipe section.

[0090] In one embodiment of the present invention, a flow rate sensor is installed at a key position of the pumping pipeline (such as the pump outlet or the main delivery pipe) to measure the flow rate of the concrete pump. , according to the concrete pump flow Calculate the average flow rate of concrete in the small diameter pump pipe section and the average flow velocity of concrete in the large diameter pump pipe section :

[0091]

[0092] in, represents the cross-sectional area of ​​the small diameter pump tube section, Indicates the inner diameter of the small diameter pump pipe section, represents the cross-sectional area of ​​the large diameter pump pipe section, Indicates the inside diameter of the large diameter pump tubing section.

[0093] The present invention improves the calculation accuracy of the total pumping resistance of the pumping pipeline during the pumping process through the dynamic rheological properties of concrete, the environmental temperature and humidity effects, the pipeline geometric parameters and the pumping process parameters, effectively reduces the engineering risks and improves the safety of pumping construction.

[0094] In one embodiment of the present invention, independent flow velocity sensors are respectively provided in the small diameter pump pipe section and the large diameter pump pipe section. The average flow velocity of concrete in the small diameter pump pipe section is and the average flow velocity of concrete in the large diameter pump pipe section The filtered readings of the flow rate sensor can be used directly.

[0095] In one embodiment of the present invention, when the diameter of the large-diameter pump pipe section is 600 mm, Take 1.00, when the pipe diameter is 1500mm, Take 1.09, and use linear interpolation to calculate the intermediate pipe diameter value.

[0096] In one embodiment of the present invention, when the ratio of the concrete pump distribution valve switching time to the piston pushing concrete is 0.3, and the ratio of the radial to axial pressure of the pumped concrete is 0.9, a total of 7 sets of calculated values ​​and test values ​​for the actual bridge pouring are compared. The results are shown in Table 1:

[0097]

[0098] It can be seen from Table 1 that the deviation rate between the calculated value and the test value is ≤-3.37%, that is, the calculated results are in good agreement with the test results, indicating that it is feasible to use the above formula to calculate the pumping pressure of concrete in the pump pipe.

[0099] In one embodiment of the present invention, a large-diameter pump pipe section was subjected to real bridge pouring, and the pressure loss values ​​of a total of 9 groups of large-diameter pump pipe sections were compared with the test values. The results are shown in Table 2:

[0100] Table 2 Comparison of measured and calculated values ​​of concrete pumping pressure in steel pipes

[0101]

[0102] 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 is ≤9.77%, that is, the pressure loss results of the large-diameter pump pipe section are in good agreement with the test results, 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 concrete pumping pressure in the main arch steel pipe.

[0103] Furthermore, the pumping resistance calculation method further includes:

[0104] Set pumping safety factor;

[0105] Calculating the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance;

[0106] The pumping pressure requirement of the pumping pipeline is compared with the rated pumping resistance of the pump machine, and the pumping equipment parameters are adjusted.

[0107] The calculation method of the pumping resistance of self-compacting concrete is described in detail with a specific embodiment:

[0108] The dense skeleton theory was used to prepare the concrete in the tube. Through the relevant tests on concrete working performance, the various properties of the concrete should meet the pumpability index requirements of the main concrete of the steel tube concrete arch bridge. As shown in Table 3, the volume stability of the main concrete of the steel tube concrete 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 air content is: the air content of concrete in the steel pipe should not exceed 2.5%:

[0109]

[0110] Among them, pouring time refers to the time from when concrete leaves the mixing station to when the pouring of a single main pipe is completed;

[0111] The dynamic plastic viscosity is calculated based on the initial plastic viscosity of the concrete tested in the concrete test, and the viscosity coefficient is calculated;

[0112] According to the pumping grouting construction organization arrangement, determine the pumping speed and calculate the speed coefficient;

[0113] The resistance along the horizontal pump pipe concrete pumping pressure is calculated based on the dynamic plastic viscosity, viscosity coefficient and velocity coefficient. According to the actual layout of the pump pipe on site, it is converted into the horizontal pump pipe layout length L to obtain the pumping resistance of concrete in the small diameter pump pipe section.

[0114] The pumping pressure required for the concrete to move in the main arch steel tube is calculated based on the sagittal height of the steel tube concrete arch bridge;

[0115] The total pumping resistance is determined 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, local losses, and the pump's own losses. The power of the pump, the wall thickness of the pump pipe, and the specifications of the pump pipe caliper are determined based on the total pumping resistance.

[0116] Verify that the pump's maximum pumping resistance meets actual pumping requirements. This should satisfy the following: Total pumping resistance required for concrete pumping (P x 1.5) ≤ Maximum pumping resistance (using a safety factor of 1.5). If this is not true, replace the pump with a higher-power pump, reduce the plastic viscosity of the concrete, decrease the pumping speed, or increase the pump pipe diameter.

[0117] The pumping resistance calculation formula for concrete in the small-diameter pump pipe section proposed in the experiment was compared with the measured pumping pressure values ​​of the actual bridge. The units of the calculated and measured resistance along the horizontal pump pipe are pressure gradient, that is, pressure loss per unit length. The comparison results are shown in Table 4 below:

[0118]

[0119] According to the above table, it can be seen that the calculated value of the horizontal pump pipe pumping pressure proposed in this test is in good agreement with the actual measured value. Through this corrected calculation method, the pumping pressure value of the concrete in the horizontal pump pipe can be calculated more accurately, providing guidance for engineering practice.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for calculating the pumping resistance of self-compacting concrete, characterized by: The following steps are involved: S1. Establishing an initial pumping parameter model based on the geometric parameters of the pumping pipeline, the initial physical properties of the self-compacting concrete, and the pumping process parameters; S2. Real-time collection of pumping condition data and digital filtering of the concrete flow rate in the pumping condition data to obtain a filtered concrete flow rate, wherein the pumping condition data includes pumping time, pumping ambient temperature, relative humidity, and concrete flow rate in the pumping pipeline; S3. Calculating the dynamic plastic viscosity of the self-compacting concrete under the current working conditions using a dynamic rheological evolution model based on the pumping time, pumping ambient temperature, and relative humidity; 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: The temperature effect model and the humidity effect model are used to calculate the comprehensive temperature and humidity correction factor of the plastic viscosity according to the pumping environment temperature and relative humidity and in combination with the model parameter set; Substituting the pumping time and the model parameter set into the basic evolution function to calculate the time correction factor; The initial plastic viscosity, the comprehensive temperature and humidity correction factor, and the time correction factor are calculated to obtain the dynamic plastic viscosity of the self-compacting concrete under the current working conditions. The calculation formula for the dynamic plastic viscosity of the self-compacting concrete under the current working conditions is: ； ； ； ； in, 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. Indicates the time the pumping has been running, represents the initial plastic viscosity, represents the base viscosity coefficient, represents the expansion influence coefficient, represents the slump influence coefficient, Indicates the degree of expansion, Indicates slump, represents the time correction factor, The final setting time of concrete. Indicates the initial setting time of concrete. Indicates the comprehensive temperature and humidity correction factor for plastic viscosity, Parameter representing the temperature sensitivity of plastic viscosity, represents the reference temperature, represents the actual average temperature of the concrete, represents the sensitivity index of plastic viscosity to humidity, n represents the rheological time evolution index, represents the plastic viscosity growth coefficient; S4. Calculate the pressure loss of different sections of the pumping pipeline based on the initial pumping parameter model, dynamic plastic viscosity, and filtered concrete flow rate, and obtain the total pumping resistance based on the pressure loss of each section; the dynamic pressure loss of the small-diameter pump pipe section is calculated as follows: ； ； ； in, Indicates the dynamic pressure loss in the small diameter pump pipe section, Indicates the radius of the concrete delivery pipe, represents the dynamic adhesion coefficient, represents the dynamic speed coefficient, Indicates the time it takes for the piston to push the concrete. Indicates the switching time of the concrete pump distribution valve, It represents the ratio of radial to axial pressure of pumped concrete. represents the proportionality coefficient of the adhesion coefficient, It represents the dynamic plastic viscosity 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 constant correction term of the adhesion coefficient, Indicates the influence factor of flow velocity on velocity coefficient, Indicates the average flow velocity of concrete in the small diameter pump pipe section, represents the adjustment constant of the speed coefficient, Indicates the length of the small diameter pump pipe section; The calculation formula for the total dynamic pressure loss in the large diameter pump pipe section is: ； ； ； in, Indicates the pressure loss in the large diameter pump pipe section, Indicates the comprehensive correction coefficient of pipe diameter enlargement and gravity effect, represents the density of self-compacting concrete, represents the acceleration due to gravity, Indicates the vertical pumping height of the large diameter pump pipe section, represents the pressure loss correction term for the large diameter pump pipe section, represents the adjustment coefficient of the friction viscosity term, represents the base flow resistance factor, Indicates the influence coefficient of expansion on flow resistance factor, Indicates the influence coefficient of slump on flow resistance factor, Indicates the length of the large diameter pump pipe section, Indicates the inner diameter of the large diameter pump pipe section, Indicates the average flow velocity of concrete in the large diameter pump pipe section, Indicates the dynamic pressure loss in the large diameter pump pipe section.

2. The method for calculating pumping resistance of self-compacting concrete according to claim 1, wherein: 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, initial plastic viscosity, slump, expansion, initial setting time, final setting time and pouring time; the pumping process parameters include the flow rate of the concrete pump, the time for the piston to push concrete and the switching time of the concrete pump distribution valve.

3. The method for calculating pumping resistance of self-compacting concrete according to claim 2, wherein: The model parameter set includes a baseline viscosity coefficient, an expansion influence coefficient, a slump influence coefficient, 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 baseline flow resistance factor, an influence coefficient of expansion on the flow resistance factor, and an influence coefficient of slump on the flow resistance factor.

4. A method for calculating pumping resistance of self-compacting concrete according to claim 3, 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.

5. The method for calculating pumping resistance of self-compacting concrete according to claim 4, wherein: Step S4 specifically includes: The dynamic plastic viscosity is used to calculate the dynamic adhesion coefficient, the filtered concrete flow velocity is used to calculate the dynamic velocity coefficient, and the dynamic pressure loss of the small diameter pump pipe section is calculated in combination with the pipeline geometric parameters and the pumping process parameters; calculating the pressure loss of 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, calculating a pressure loss correction term for the large diameter pump pipe section based on friction and viscosity of the large diameter pump pipe section, and obtaining a 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; The total pumping resistance is obtained 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 machine itself.

6. The method for calculating pumping resistance of self-compacting concrete according to claim 1, wherein: The pumping resistance calculation method further includes: Set pumping safety factor; Calculating the pumping pressure requirement of the pumping pipeline based on the pumping safety factor and the total pumping resistance; The pumping pressure requirement of the pumping pipeline is compared with the rated pumping resistance of the pump machine, and the pumping equipment parameters are adjusted.

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