A method and system for controlling the steam curing of tube segments in a universal steam curing kiln.

Abstract

This invention discloses a method and system for controlling the steam curing of tunnel segments in a universal steam curing kiln, relating to the field of tunnel segment steam curing technology. The method includes: determining the key hydration time sequence for segments of different permeability grades under different steam curing modes based on segment impermeability grade information and concrete mix proportion data; establishing differentiated steam curing parameter sets for individual and overall steam curing modes; calculating the energy utilization rate and temperature uniformity under the current steam curing mode based on the thermal fluid boundary layer theory according to the segment entry sequence information, and determining mode switching conditions to complete the switching between different steam curing modes; adjusting the steam pipeline supply and steam curing temperature based on the current steam curing mode and mode switching conditions to ensure the quality of segment steam curing. This invention can accurately control both individual and overall steam curing modes, fully leveraging the advantages of a universal steam curing kiln that combines the benefits of both independent and interconnected kilns.

Description

Technical Field

[0001] This invention relates to the field of tube segment steam curing technology, and more specifically, to a tube segment steam curing control method and system for a general-purpose tube segment steam curing kiln. Background Technology

[0002] With the rapid development of urban infrastructure construction, shield tunneling has been widely used in large-scale projects such as subways and undersea tunnels. In shield tunnel engineering, the tunnel segments, as the core component of the support structure, directly affect the safety and service life of the tunnel. Especially in shield tunnel projects such as undersea tunnels with large diameters, deep burial, and high water pressure, the concrete performance requirements for the tunnel segments are extremely high. Generally, C60 high-performance double-blended concrete is used, and different impermeability grades (P15, P12) are set according to different water pressure conditions. In the process of segment production, steam curing is a key process to ensure the early strength and impermeability of concrete. By controlling temperature and humidity conditions, the hydration reaction of concrete is accelerated, improving the quality of the tunnel segments. With the expansion of the scale of tunnel segment production and the improvement of process requirements, traditional steam curing equipment can no longer meet the differentiated, high-efficiency, and high-quality production needs.

[0003] Currently, there are two main types of tube-section steam curing kilns: independent kilns and multi-section kilns. Independent kilns allow for individual steam curing of each tube section, enabling precise control of each individual section, but they require a large footprint and have low energy efficiency. Multi-section kilns, on the other hand, place multiple tube sections in a single large kiln for unified steam curing. While this improves energy efficiency, it cannot provide differentiated control for different types of tube sections, and the uneven temperature distribution can easily lead to fluctuations in tube quality. To address these issues, universal tube-section steam curing kilns have emerged. Through modular design, they can be used individually like independent kilns or in combination like multi-section kilns. They are equipped with an intelligent control system that monitors parameters such as temperature and humidity in real time during the steam curing process and employs advanced heat recovery technology to improve energy efficiency. However, the current control methods for universal steam curing kilns still have many shortcomings, making it difficult to fully realize their technological advantages.

[0004] Existing methods for controlling the steam curing of tunnel segments suffer from two main problems: First, they cannot achieve flexible switching and precise control of the steam curing mode. When production demand increases from single-shift operation (e.g., 60 rings / month) to double-shift operation (e.g., 120 rings / month), existing control methods cannot intelligently adjust the steam curing mode based on the segment entry sequence information, leading to energy waste and low kiln utilization. Second, they cannot implement differentiated steam curing control for segments with different impermeability grades. Existing methods often use a uniform steam curing curve, ignoring the differences in material properties, pore distribution, and hydration processes among segments with different impermeability grades (e.g., P15 and P12). This results in unsatisfactory steam curing effects for some segments, making it difficult to meet the stringent requirements for segments in high-water-pressure sections of tunnel engineering. Furthermore, existing control methods lack precise monitoring and regulation of the temperature field distribution during steam curing, failing to ensure temperature uniformity within the steam curing kiln. This leads to unstable segment curing quality, affecting the impermeability and service life of the final product.

[0005] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0006] To address the problems in related technologies, this invention proposes a method and system for controlling the steam curing of pipe segments in a universal steam curing kiln. This system has the advantages of being able to flexibly switch modes and achieve differentiated and precise control based on the characteristics of pipe segments with different impermeability grades. This solves the problems in existing technologies that cannot meet the needs of different production scales and lack differentiated steam curing control for pipe segments with different impermeability grades.

[0007] Therefore, the specific technical solution adopted by the present invention is as follows:

[0008] According to one aspect of the present invention, a method for controlling the steam curing of tube segments in a universal steam curing kiln for tube segments is provided, the method comprising:

[0009] S1. Based on the segment impermeability grade information and concrete mix proportion data, determine the key hydration time node sequence of segments with different impermeability grades under different steam curing modes, and establish a differentiated steam curing parameter set under individual steam curing mode and overall steam curing mode.

[0010] S2. Based on the segment entry sequence information and the differentiated steam curing parameter set, select the current steam curing mode, calculate the energy utilization rate and temperature uniformity under the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode switching conditions to complete the switching of different steam curing modes.

[0011] S3. Based on the current steam curing mode and mode conversion conditions, adjust the steam pipeline supply and steam curing temperature to ensure the quality of tube segment steam curing.

[0012] Furthermore, to improve the steam curing quality of pipe segments with different impermeability grades, based on the impermeability grade information of the segments and concrete mix proportion data, the key hydration time node sequence of segments with different impermeability grades under different steam curing modes was determined, and a differentiated steam curing parameter set was established under individual steam curing mode and overall steam curing mode, including:

[0013] S11. Based on the permeability grade information of the pipe segments and the concrete mix proportion data, obtain the material property parameter matrix of pipe segments with different permeability grades, and analyze the pore characteristics of the pipe segments to obtain pore distribution characteristic data.

[0014] S12. Using a multi-point temperature and humidity sensor array, monitor the hydration heat release curve and temperature field distribution of pipe segments of each anti-seepage grade under individual steam curing mode and overall steam curing mode, and determine the key hydration time node sequence under different steam curing modes.

[0015] S13. Based on the key hydration time node sequence and pore distribution characteristic data, calculate the weight coefficients of different steam curing stages, and combine them with the benchmark steam curing parameters to generate a set of differentiated steam curing parameters for segments with different impermeability grades.

[0016] Furthermore, to analyze the material properties of different tunnel segments, based on the segment impermeability grade information and concrete mix proportion data, a material property parameter matrix for segments with different impermeability grades was obtained. The pore characteristics of the segments were also analyzed, yielding pore distribution characteristic data including:

[0017] S111. Based on the concrete mix proportion, extract the water-cement ratio and mineral admixture content of pipe segments with different impermeability grades, and construct a material property parameter matrix;

[0018] S112. Using a permeability meter, gradient water pressure is applied to pipe segment test blocks with different anti-permeability grades, the relationship between permeation depth and time is recorded, and the permeability coefficient and critical permeation pressure value are obtained by data fitting.

[0019] S113. Based on the permeability coefficient and critical osmotic pressure value, and combined with the material characteristic parameter matrix, calculate the pore size distribution and porosity of pipe segments with different anti-permeability grades using the capillary bundle method, and establish a pore distribution characteristic data table.

[0020] Furthermore, to differentiate the hydration process characteristics under different steam curing modes, a multi-point temperature and humidity sensor array was used to monitor the hydration heat release curves and temperature field distribution of segments of different impermeability grades under both individual and overall steam curing modes. The key hydration time node sequences under different steam curing modes were determined to include:

[0021] S121. In the single steam curing mode, the temperature field distribution and hydration heat release rate of a single tube segment are monitored by a multi-point temperature and humidity sensor array to identify the initial setting time point, final setting time point, hydration peak time point and strength target achievement time point, forming the first hydration time node sequence.

[0022] S122. In the overall steam curing mode, the temperature field distribution and hydration heat release curve of multiple tube segments are monitored synchronously through a distributed temperature and humidity sensor network to identify the group hydration synchronization point, temperature equilibrium point and overall intensity target point, forming a second hydration time node sequence.

[0023] S123. Based on the first hydration time node sequence and the second hydration time node sequence, calculate the peak time difference and temperature difference of hydration heat release for the same anti-permeability grade pipe segments under different steam curing modes, and generate the key hydration time node sequence.

[0024] Furthermore, to optimize the configuration of steam curing process parameters, weighting coefficients for different steam curing stages are calculated based on key hydration time node sequences and pore distribution characteristics. Combined with baseline steam curing parameters, a differentiated steam curing parameter set for segments with different impermeability grades is generated, including:

[0025] S131. The steam curing process of the tube segments is divided into a preheating stage, a constant temperature holding stage, and a cooling stage. An evaluation system for the steam curing stage is established using the analytic hierarchy process. A judgment matrix is ​​constructed based on the pore distribution characteristic data and the key hydration time node sequence as the judgment criteria.

[0026] S132. By calculating the eigenvalues ​​and eigenvectors of the judgment matrix, the weighting coefficients of the influence of different steam curing stages on the anti-seepage performance of the pipe segments are obtained.

[0027] S133. Based on the benchmark steam curing parameters and weighting coefficients, calculate the temperature setpoint, steam supply and duration of pipe segments with different anti-permeability grades under different steam curing modes, and record the parameter difference rate, conversion sensitivity and adaptability range between the two modes to form a differentiated steam curing parameter set.

[0028] Furthermore, to achieve intelligent switching of steam curing modes, the current steam curing mode is selected based on the segment entry sequence information and a differentiated steam curing parameter set. The energy utilization rate and temperature uniformity under the current steam curing mode are calculated based on the thermofluid boundary layer theory, and the mode switching conditions are determined to complete the switching between different steam curing modes, including:

[0029] S21. Obtain the current production plan data and the sequence of segments entering the kiln. Based on the distribution of the segments' impermeability level and the sequence of segments entering the kiln, and combined with the differentiated steam curing parameter set, calculate the expected hydration heat distribution under different combination schemes, and select the current steam curing mode.

[0030] S22. Based on the thermal fluid boundary layer theory, the steam flow characteristics and heat exchange efficiency of the tube surface are monitored in real time by a multi-point temperature and humidity sensor array. The energy utilization rate and temperature uniformity under the current steam curing mode are calculated to determine the mode switching conditions.

[0031] S23. When the mode switching conditions are met, an instruction is issued according to the position distribution of the tube segments in the curing kiln to control the tie rod mechanism to push the mold to move, so as to complete the switching of different steam curing modes.

[0032] According to another aspect of the present invention, a tube curing control system for a universal tube curing kiln is also provided, the tube curing control system comprising:

[0033] The parameter setting unit is used to determine the key hydration time node sequence of segments with different permeability grades under different steam curing modes based on the segment permeability grade information and concrete mix proportion data, and to establish a differentiated steam curing parameter set under individual steam curing mode and overall steam curing mode.

[0034] The mode control unit is used to select the current steam curing mode based on the segment entry sequence information and the differentiated steam curing parameter set, calculate the energy utilization rate and temperature uniformity of the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode switching conditions to complete the switching of different steam curing modes.

[0035] The control unit is used to adjust the steam supply and steam curing temperature based on the current steam curing mode and mode switching conditions to ensure the quality of the tube segment steam curing.

[0036] The beneficial effects of this invention are as follows:

[0037] (1) This invention determines the key hydration time node sequence and establishes a differentiated steam curing parameter set by using the permeability grade information of the pipe segments and the concrete mix proportion data. It can implement precise control for pipe segments of different permeability grades (P15 and P12) in both individual steam curing and overall steam curing modes, giving full play to the characteristics of the general-purpose steam curing kiln which has the advantages of both independent kiln and kiln. At the same time, this method uses a multi-point temperature and humidity sensor array to monitor the environmental parameters inside the kiln in real time, which can automatically adjust the amount of steam and temperature, making the temperature rise and fall more precise, avoiding temperature cracks caused by sudden temperature rise and fall when the pipe segments enter and exit the kiln, ensuring the steam curing effect in every corner, thereby significantly improving the permeability performance of the pipe segments and the quality of concrete.

[0038] (2) This invention intelligently selects the current steam curing mode based on the information of the tube segments entering the kiln and the differentiated steam curing parameter set, and calculates the energy utilization rate and temperature uniformity based on the thermal fluid boundary layer theory. When the mode conversion conditions are met, it automatically completes the switching of different steam curing modes, so that the general-purpose steam curing kiln can be used alone like an independent kiln or in combination like a general kiln. This modular design and flexible switching mechanism greatly improves the adaptability of the steam curing kiln. It can meet the needs of different production scales such as single-shift operation (60 rings / month) and double-shift operation (120 rings / month). It can also complete the mode conversion by controlling the tie rod mechanism to push the mold to move, avoiding problems such as temperature loss and sudden cooling at the inlet and outlet positions caused by the opening and closing of the steam curing kiln. At the same time, it improves the mold turnover rate and shortens the casting cycle.

[0039] (3) The steam curing control method of the present invention adopts advanced heat energy recovery technology and intelligent control system, and combines the hierarchical analysis method to calculate the weight coefficients of different steam curing stages, so that the steam curing kiln is more tightly sealed and effectively prevents steam from escaping to the outside of the steam curing kiln; the method puts the finishing process into the steam curing kiln, avoiding the disturbance of concrete caused by moving the mold during the finishing process, and at the same time reducing the length of the production line, saving the space required for the mold of the cast segment during the finishing process when continuously pouring; in addition, the use of steam pipelines, temperature sensors and other equipment in the steam curing kiln in conjunction with the steam curing monitoring system realizes real-time monitoring and precise control of the kiln environment, avoids the temperature from rising too fast or too slow, ensures the quality and stability of the steam curing effect, and avoids water vapor accumulation in the workshop causing obstruction of vision or equipment failure due to rainwater. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic flowchart of a tube segment steam curing control method for a universal tube segment steam curing kiln according to an embodiment of the present invention;

[0042] Figure 2 This is a detailed implementation diagram of a method for controlling the steam curing of tube segments in a general-purpose steam curing kiln for tube segments, according to an embodiment of the present invention, which establishes a differentiated steam curing parameter set for individual steam curing modes and overall steam curing modes;

[0043] Figure 3 This is an overall process flow diagram of a tube segment steam curing control method for a universal tube segment steam curing kiln according to an embodiment of the present invention;

[0044] Figure 4This is a schematic block diagram of a tube-segment steam curing control system for a universal tube-segment steam curing kiln according to an embodiment of the present invention;

[0045] Figure 5 This is a real-time monitoring diagram of steam curing kiln data for a universal steam curing kiln for tube segments according to an embodiment of the present invention.

[0046] Figure 6 This is a diagram of the steam curing kiln production line monitoring interface according to an embodiment of the present invention, which is a method for controlling the steam curing of tube segments in a general-purpose steam curing kiln. Detailed Implementation

[0047] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0048] According to embodiments of the present invention, a method and system for controlling the steam curing of tube segments in a universal steam curing kiln for tube segments is provided.

[0049] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, according to an embodiment of the present invention, a method for controlling the steam curing of tube segments in a universal steam curing kiln for tube segments is provided. This method includes:

[0050] S1. Based on the permeability grade information of the pipe segments and the concrete mix proportion data, determine the key hydration time node sequence of pipe segments of each permeability grade under different steam curing modes, and establish a differentiated steam curing parameter set for pipe segments of different permeability grades under individual steam curing mode and overall steam curing mode.

[0051] S2. Based on the segment entry sequence information and the differentiated steam curing parameter set, select the current steam curing mode, calculate the energy utilization rate and temperature uniformity under the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode switching conditions to complete the switching of different steam curing modes.

[0052] S3. Based on the current steam curing mode and mode conversion conditions, adjust the steam pipeline supply and steam curing temperature to ensure the quality of tube segment steam curing.

[0053] In one embodiment, such as Figure 2As shown, based on the segment permeability grade information and concrete mix proportion data, the key hydration time node sequence of segments with different permeability grades under different steam curing modes is determined, and a differentiated steam curing parameter set for segments with different permeability grades under individual steam curing mode and overall steam curing mode is established, including:

[0054] S11. Based on the permeability grade information of the pipe segments and the concrete mix proportion data, obtain the material property parameter matrix of pipe segments with different permeability grades, and analyze the pore characteristics of the pipe segments to obtain pore distribution characteristic data.

[0055] S12. Using a multi-point temperature and humidity sensor array, monitor the hydration heat release curve and temperature field distribution of pipe segments of each anti-seepage grade under individual steam curing mode and overall steam curing mode, and determine the key hydration time node sequence under different steam curing modes.

[0056] S13. Based on the key hydration time node sequence and pore distribution characteristic data, calculate the weight coefficients of different steam curing stages, and combine them with the benchmark steam curing parameters to generate a set of differentiated steam curing parameters for segments with different impermeability grades.

[0057] In one embodiment, based on the segment impermeability grade information and concrete mix proportion data, a material property parameter matrix for segments with different impermeability grades is obtained, and the pore characteristics of the segments are analyzed to obtain pore distribution characteristic data, including:

[0058] S111. Based on the concrete mix proportion, extract the water-cement ratio and mineral admixture content of pipe segments with different impermeability grades, and construct a material property parameter matrix;

[0059] S112. Using a permeability meter, gradient water pressure is applied to pipe segment test blocks with different anti-permeability grades, the relationship between permeation depth and time is recorded, and the permeability coefficient and critical permeation pressure value are obtained by data fitting.

[0060] S113. Based on the permeability coefficient and critical osmotic pressure value, and combined with the material characteristic parameter matrix, calculate the pore size distribution and porosity of pipe segments with different anti-permeability grades using the capillary bundle method, and establish a pore distribution characteristic data table.

[0061] Specifically, taking a large-scale undersea tunnel project in a coastal city as an example, this project selected two types of tunnel segments with different impermeability grades: P15 grade segments for depths with water pressure ≥ 60m and P12 grade segments for depths with water pressure ≤ 60m. For P15 grade segments, C60 high-performance double-admixed concrete was prepared with a water-cement ratio controlled at 0.29, and 30% mineral powder and 8% silica fume were added; while for P12 grade segments, the C60 concrete had a water-cement ratio of 0.32, and 25% mineral powder and 5% silica fume were added. First, the concrete mix proportion data of the two types of segments were collected, and six key parameters were extracted: water-cement ratio (w / b), total mineral admixture content (MA), mineral powder content (GGBS%), silica fume content (SF%), alkali content (Na2Oeq), and water-reducing agent content (SP%), to construct a 6×2 material property parameter matrix. Subsequently, in accordance with the "Test Procedures for Hydraulic Concrete", a GJL-6 concrete permeability tester was used to test the permeability of standard-cured test blocks (100mm×100mm×100mm) and steam-cured test blocks of two types of pipe segments. An initial water pressure of 0.2MPa was applied and maintained for 8 hours, then increased by 0.3MPa every 12 hours until the water pressure reached the upper limit of the required permeability grade for the samples. By recording the penetration depth and corresponding time of the test blocks at each water pressure level, a hyperbolic fitting model was used to calculate the permeability coefficient of the P15 grade steam-cured pipe segment as 3.2×10⁻⁶. -14 With a flow rate of m / s and a critical osmotic pressure of 1.65 MPa, the permeability coefficient of P12 grade steam-cured pipe segments is 7.8 × 10⁻⁶ m / s. -14 The surface tension (m / s) and critical osmotic pressure (COP) are 1.28 MPa. Based on these data, the pore size distribution and porosity are calculated using a modified capillary bundle method. The specific calculation formula is r = 2σcosθ / p, where r is the pore size, σ is the surface tension, θ is the contact angle, and p is the pressure. Calculations show that the harmful porosity (>100 nm) of P15 grade segments is 2.31%, and the total porosity is 6.42%; the harmful porosity of P12 grade segments is 3.65%, and the total porosity is 8.17%. Finally, the above data are integrated into a pore distribution characteristic data table to provide a basis for the subsequent design of differentiated steam curing parameters.

[0062] In one embodiment, a multi-point temperature and humidity sensor array is used to monitor the hydration heat release curves and temperature field distribution of segments of different impermeability grades under both individual steam curing and overall steam curing modes, respectively, to determine the key hydration time node sequence under different steam curing modes, including:

[0063] S121. In the single steam curing mode, the temperature field distribution and hydration heat release rate of a single tube segment are monitored by a multi-point temperature and humidity sensor array to identify the initial setting time point, final setting time point, hydration peak time point and strength target achievement time point, forming the first hydration time node sequence.

[0064] S122. In the overall steam curing mode, the temperature field distribution and hydration heat release curve of multiple tube segments are monitored synchronously through a distributed temperature and humidity sensor network to identify the group hydration synchronization point, temperature equilibrium point and overall intensity target point, forming a second hydration time node sequence.

[0065] S123. Based on the first hydration time node sequence and the second hydration time node sequence, calculate the peak time difference and temperature difference of hydration heat release for the same anti-permeability grade pipe segments under different steam curing modes, and generate the key hydration time node sequence.

[0066] Specifically, the individual steam curing mode includes: placing a single segment mold independently in the steam curing kiln for steam curing, and achieving individual temperature and humidity control through a modular sealing device; the overall steam curing mode includes: placing multiple segment molds together in the steam curing kiln for steam curing, and achieving overall temperature and humidity control through a unified steam pipeline system.

[0067] It should be noted that a multi-point temperature and humidity sensor array refers to setting 3-5 temperature and humidity sensors at different locations on a single tube segment, respectively arranged at the top, bottom, side, and center of the tube segment. This allows for real-time monitoring of the temperature field distribution and hydration heat release rate of the single tube segment, identifying the initial setting time, final setting time, hydration peak time, and strength attainment time, forming the first hydration time node sequence. A distributed temperature and humidity sensor network refers to setting multiple sets of temperature and humidity sensors in a grid-like layout within the steam curing kiln. Each set of sensors is responsible for monitoring a group of tube segments within a specific area. The sensors transmit data synchronously through a wireless communication module, monitoring the temperature field uniformity and hydration heat release curves of multiple tube segments, identifying the group hydration synchronization point, temperature equilibrium point, and overall strength attainment point, forming the second hydration time node sequence.

[0068] Specifically, the sequence of the first hydration time nodes includes:

[0069] Based on the collected temperature data of a single tube segment, the rate of temperature change between two adjacent sampling time points is calculated, a time series of temperature change rate is generated, and the temperature change rate curve is obtained after smoothing.

[0070] The point where the slope of the temperature change rate curve changes sign is determined. When the slope changes from negative to positive and the rate of change is greater than a preset first threshold, the time point is determined as the initial condensation time point.

[0071] When the rate of temperature change first reaches the preset proportion of its maximum value, it is marked as the start time of rapid hydration; when the rate of temperature change reaches its maximum value, it is marked as the peak time of hydration.

[0072] When the rate of temperature change drops from the peak to a preset percentage of the maximum value and the rate of change at multiple consecutive sampling points is less than a preset second threshold, it is marked as the critical time point for hydration termination.

[0073] The different time points are arranged in chronological order to form the first hydration time node sequence.

[0074] Specifically, the sequence of time nodes for forming the second hydration includes:

[0075] Based on the temperature data of each tube segment within the same steam curing cycle, the tube segments are grouped according to their spatial position in the steam curing kiln, with each group containing several tube segments.

[0076] Calculate the average temperature and temperature standard deviation of each group of segments at the same time point, and plot the curve of standard deviation changing over time.

[0077] When the temperature standard deviation of all groups is simultaneously less than the preset temperature deviation value and continues for more than the preset time, the starting point of this time period is determined as the group hydration synchronization point.

[0078] Calculate the temperature gradient between different measuring points in the steam curing kiln. When the maximum temperature gradient value is less than the preset gradient threshold and continues for more than the preset duration, mark the starting point of this time period as the temperature equilibrium point.

[0079] Based on the pre-established temperature-strength correspondence, when the calculated equivalent strength reaches the preset percentage of the design strength, the time point is marked as the overall strength compliance point;

[0080] The hydration synchronization point, temperature equilibrium point, and overall strength attainment point are arranged in chronological order to form the second hydration time node sequence.

[0081] Specifically, in the aforementioned mega-scale bay area subsea tunnel project, steam curing process tests were conducted on tunnel segments of two impermeability grades: P15 and P12, using DS-T840 high-precision temperature and humidity sensors. In standalone steam curing mode, tests were performed on a standard tunnel segment (outer diameter 11.6m). Five temperature and humidity sensors were placed on the inner and outer surfaces, the top arc section, the bottom arc section, and the central area of ​​the segment. The sampling frequency was set to collect data once per minute, and the data was transmitted to the steam curing monitoring system. The collected temperature data was smoothed using the Savitzky-Golay filtering algorithm to eliminate the influence of measurement noise on the calculation of the temperature change rate. Through experiments, the temperature change rate threshold at the initial setting time of P15 grade segments was determined to be 0.25℃ / min. The temperature change rate at the rapid hydration start time point reached 75% of the maximum value. The average temperature change rate at the hydration peak time point was 1.82℃ / min. The hydration termination critical time point was determined when the temperature change rate dropped from the peak to 15% of the maximum value and the change rate at 5 consecutive sampling points was less than 0.08℃ / min.

[0082] Specifically, in the overall steam curing mode, eight tube segments were arranged in a 2×4 matrix within the steam curing kiln. The kiln's internal dimensions were 12.5m × 25.0m × 3.5m (height), and a total of 24 temperature and humidity sensor nodes were installed, distributed in a 3-layer, 8-node spatial grid. Each node used an STM32F103C8T6 chip as its control core, in conjunction with an SHT31 temperature and humidity sensor module, and achieved synchronous data transmission via a ZigBee wireless network (CC2530 chip), with a sampling period of 30 seconds. To ensure measurement accuracy, the system underwent multi-point calibration before the experiment, and an automatic temperature compensation algorithm was implemented. Through repeated experiments, the criteria for determining the synchronous hydration point of the group were: the temperature standard deviation of all measurement points in the group is simultaneously less than 1.2℃ and the duration exceeds 25 minutes; the criteria for determining the temperature equilibrium point are: the maximum temperature gradient value in the kiln is less than 0.8℃ / m and the duration exceeds 40 minutes; the overall strength attainment point is determined based on the established temperature-strength mapping model, through integral calculation to determine the equivalent age of C60 concrete, and is marked as the attainment point when the equivalent strength reaches 70% of the design strength (approximately 42MPa). Using the above methods, the key time node sequences of P15 and P12 grade segments under the overall steam curing mode were successfully identified, providing data support for the optimization of process parameters under the two steam curing modes.

[0083] In one embodiment, based on the key hydration time node sequence and pore distribution characteristic data, weight coefficients for different steam curing stages are calculated, and combined with baseline steam curing parameters, a differentiated steam curing parameter set for segments with different impermeability grades is generated, including:

[0084] S131. The steam curing process of the tube segments is divided into a preheating stage, a constant temperature holding stage, and a cooling stage. An evaluation system for the steam curing stage is established using the analytic hierarchy process. A judgment matrix is ​​constructed based on the pore distribution characteristic data and the key hydration time node sequence as the judgment criteria.

[0085] S132. By calculating the eigenvalues ​​and eigenvectors of the judgment matrix, the weighting coefficients of the influence of different steam curing stages on the anti-seepage performance of the pipe segments are obtained.

[0086] S133. Based on the benchmark steam curing parameters and weighting coefficients, calculate the temperature setpoint, steam supply and duration of pipe segments with different anti-permeability grades under different steam curing modes, and record the parameter difference rate, conversion sensitivity and adaptability range between the two modes to form a differentiated steam curing parameter set.

[0087] Specifically, this invention focuses on P15 and P12 grade pipe segments required for a large-scale bay area subsea tunnel project. The steam curing process is divided into three key stages: preheating (T1, 2-4 hours), constant temperature maintenance (T2, 6-8 hours), and cooling (T3, 3-4 hours). An evaluation system is established using the analytic hierarchy process (AHP), selecting pore distribution characteristics and hydration time points as judgment criteria. Pore characteristics include total porosity (C1), harmful porosity (C2), and critical pore size (C3). Hydration time points include initial setting time (C4), peak hydration time (C5), and strength attainment time (C6). For P15 grade pipe segments, a 6×6 judgment matrix A is constructed. The 1-9 scaling method is used to quantify the relative importance of each criterion. The calculated maximum eigenvalue λmax = 6.185, consistency index CI = 0.037, and random consistency ratio CR = 0.03 < 0.1, indicating that the judgment matrix has satisfactory consistency. The weights of each criterion were calculated using the eigenvector method as follows: w = [0.32, 0.26, 0.15, 0.12, 0.09, 0.06]. This yielded the following weighting coefficients for the three steam curing stages on the impermeability of P15 grade pipe segments: 0.28 for the preheating stage, 0.52 for the isothermal stage, and 0.20 for the cooling stage. Similarly, the weighting coefficients for P12 grade pipe segments were: 0.25 for the preheating stage, 0.45 for the isothermal stage, and 0.30 for the cooling stage.

[0088] Specifically, based on the conventional steam curing parameters (preheating stage: 2.5 hours, heating rate 8℃ / h, steam supply 2.8t / h; constant temperature holding stage: 60±2℃, 7 hours, steam supply 1.5t / h; cooling stage: 3 hours, cooling rate 12℃ / h, steam supply 0.8t / h), and combined with weighting coefficient adjustments, the optimized parameters for P15 grade tube segments under the single steam curing mode are: preheating stage 2.8 hours, heating rate 7.5℃ / h, steam supply 2.6t / h; constant temperature holding stage 62±1℃, 7.5 hours, steam supply 1.6t / h; cooling stage 3.2 hours, cooling rate 10℃ / h, steam supply 0.9t / h). Meanwhile, by comparing and analyzing the parameter changes under the two steam curing modes, the parameter difference rate (temperature setpoint difference rate ±3%, duration difference rate ±12%, steam supply difference rate ±15%), conversion sensitivity (preheating stage 0.85, constant temperature holding stage 0.92, cooling stage 0.78) and applicable range (single shift production of 60-80 cycles / month is suitable for individual steam curing mode, double shift production of 100-120 cycles / month is suitable for overall steam curing mode) were recorded. Finally, a complete set of differentiated steam curing parameters was formed, providing a scientific basis for the conversion of steam curing modes under different production needs.

[0089] In one embodiment, the current steam curing mode is selected based on the segment entry sequence information and a differentiated steam curing parameter set. The energy utilization rate and temperature uniformity under the current steam curing mode are calculated based on the thermofluid boundary layer theory, and the mode switching conditions are determined to complete the switching between different steam curing modes, including:

[0090] S21. Obtain the current production plan data and the sequence of segments entering the kiln. Based on the distribution of the segments' impermeability level and the sequence of segments entering the kiln, and combined with the differentiated steam curing parameter set, calculate the expected hydration heat distribution under different combination schemes, and select the current steam curing mode.

[0091] Specifically, on the segment production line of this mega-scale bay area subsea tunnel project, the factory management system receives current production plan data, including monthly output requirements (120 rings / month), the proportion of segments with different impermeability grades (P15 grade accounts for 45%, P12 grade accounts for 55%), and the kiln loading sequence. Based on data analysis from the production management system, the daily kiln loading sequence shows that eight consecutive segments of the same grade (P15 grade) need to undergo steam curing treatment sequentially, and there are 12 mixed-grade segments to be processed subsequently. The system calculates the expected hydration heat distribution under both individual steam curing and overall steam curing modes based on the aforementioned differentiated steam curing parameter set. The calculation results show that, under the current kiln loading sequence, if the individual steam curing mode is used to treat these eight P15 grade segments, the expected hydration heat peak is misaligned, resulting in higher energy consumption; while using the overall steam curing mode, the hydration heat can achieve a synergistic superposition effect, reducing the expected energy consumption by 18%. Considering that the current monthly production demand is at its peak (greater than 100 rings / month), the system automatically selects the overall steam curing mode as the current steam curing mode and sets the steam curing conditions according to the differentiated steam curing parameters of P15 grade pipe segments.

[0092] S22. Based on the thermal fluid boundary layer theory, the steam flow characteristics and heat exchange efficiency of the tube surface are monitored in real time by a multi-point temperature and humidity sensor array. The energy utilization rate and temperature uniformity under the current steam curing mode are calculated to determine the mode switching conditions.

[0093] Specifically, the energy utilization rate and temperature uniformity under the current steam curing mode are calculated to determine the mode switching conditions, including:

[0094] Based on real-time monitoring data from multi-point temperature and humidity sensors, the Reynolds number and Prandtl number of the steam fluid in the steam curing kiln are calculated to determine the boundary layer flow characteristics.

[0095] Based on the boundary layer flow characteristics, the convective heat transfer coefficient and thermal resistance between the inner wall of the steam curing kiln and the surface of the tube segments are calculated.

[0096] Analyze the flow path of steam under the current steam curing mode, calculate the Nusselt number on the surface of the tube segments, and determine the heat transfer coefficient;

[0097] The effective heat transfer rate and heat loss rate per unit time are calculated by multiplying the heat transfer coefficient by the temperature gradient, thus obtaining the energy utilization rate.

[0098] Calculate the temperature uniformity index under the current steam curing mode based on the maximum temperature difference and standard deviation at each measuring point;

[0099] When the energy utilization rate is lower than the preset efficiency value or the temperature uniformity exceeds the preset fluctuation range, the mode switch is determined.

[0100] Specifically, after selecting the overall steam curing mode, the system activates the real-time monitoring and calculation module based on the thermal fluid boundary layer theory. A multi-point temperature and humidity sensor array arranged inside the steam curing kiln continuously collects data, transmitting temperature, humidity, and flow rate data to the control system every 30 seconds. The system first calculates the Reynolds number (Re) and Prandtl number (Pr) of the steam fluid. When the measured steam velocity is 0.8 m / s and the temperature is 62℃, the calculated Re is 2.3 × 10⁻⁶. 4 Pr = 1.03 indicates that the flow is turbulent. Based on the turbulent heat transfer correlation, the convective heat transfer coefficient of the tube surface is calculated to be 25 W / (m²). 2 ·K), thermal resistance is 0.04 (m) 2 ·K) / W. Subsequently, the system analyzes the steam flow path under the current overall steam curing mode, calculates the Nusselt number (Nu) on the surface of each tube segment, and determines the average heat transfer coefficient to be 28 W / (m). 2 (·K). Based on the temperature gradient data at each measuring point, the system calculated the effective heat transfer rate per unit time to be 42kW and the heat loss rate to be 7.5kW, resulting in a current energy utilization rate of 84.8%, which is higher than the preset efficiency threshold of 80%. Simultaneously, by analyzing the temperature data from 24 measuring points, the maximum temperature difference was calculated to be 2.3℃, the temperature standard deviation to be 0.85℃, and the temperature uniformity index to be 92.6%, which is better than the preset uniformity requirement of 90%. Since both energy utilization rate and temperature uniformity meet the preset conditions, the system confirms that no mode switch is needed at this time and will continue to maintain the overall steam curing mode.

[0101] S23. When the mode switching conditions are met, an instruction is issued according to the position distribution of the tube segments in the curing kiln to control the tie rod mechanism to push the mold to move, so as to complete the switching of different steam curing modes.

[0102] Specifically, during production, the system continuously monitors energy utilization and temperature uniformity indicators. When the monthly production plan is adjusted from 120 cycles / month to 75 cycles / month, the sequence of segments entering the kiln becomes intermittent, and the number of segments entering the kiln at one time decreases. At this time, the system recalculates the energy utilization rate and finds that it has dropped to 76.2%, lower than the preset efficiency threshold of 80%; the temperature uniformity indicator has also dropped to 88.5%, failing to meet the preset standard. Based on the changes in these two indicators, the system determines that the mode conversion conditions are met and triggers the steam curing mode switching process. The control system first sends a warning signal to the operating terminal, indicating that the mode conversion is about to begin; then, the system generates an optimized mold movement sequence according to the actual position distribution of the segments in the steam curing kiln and sends instructions to the hydraulic tie rod mechanism control unit. The hydraulic tie rod mechanism is activated according to the instruction sequence, pushing the mold to move along the guide rail, separating the originally uniformly arranged segment molds into independent units, and simultaneously activating the independent sealing devices and steam supply systems of each unit. The entire conversion process took about 15 minutes. The system successfully switched the overall steam curing mode to the individual steam curing mode and automatically adjusted to the corresponding differentiated steam curing parameters to ensure that the system can maintain the best energy efficiency and segment quality stability even when production needs change.

[0103] In one embodiment, the steam supply and steam curing temperature are adjusted based on the current steam curing mode and mode switching conditions to ensure the quality of the tube segment steam curing.

[0104] It should be noted that the steam supply system of the autocure kiln in this invention consists of a main steam pipeline and branch steam pipelines. The main steam pipeline connects to the high-pressure steam source in the boiler room, and the pressure is reduced to 0.6 MPa by a pressure reducing valve before entering the autocure kiln area. The branch steam pipelines control the steam supply to each autocure area or unit through a combination of electromagnetic proportional valves and flow meters. In the overall autocure mode, steam is supplied evenly mainly through annular steam distributors located at the bottom and side walls of the autocure kiln. The steam supply is calculated based on the total volume of the tube segments and the impermeability grade. In the individual autocure mode, steam is supplied directly to each tube segment mold through independent steam nozzles. The steam supply is calculated separately based on the volume of each tube segment and the impermeability grade to ensure that the hydration reaction of tube segments with different impermeability grades can be carried out within the optimal temperature range in each autocure stage, thereby ensuring that the mechanical properties and impermeability of the tube segments meet the design requirements.

[0105] Specifically, based on the current steam curing mode and mode switching conditions, this invention employs an intelligent PID control strategy to dynamically adjust the steam pipeline supply and steam curing temperature. In the overall steam curing mode, the control system divides the steam curing process into a preheating stage (20℃ to 60℃, heating rate of 15℃ / h), a constant temperature holding stage (60±1℃, lasting 8 hours), and a cooling stage (60℃ to 30℃, cooling rate not exceeding 10℃ / h) according to the temperature set curve of the differentiated steam curing parameter set. The steam flow rate is precisely controlled by a proportional regulating valve on the main steam pipeline, initially set at 45 kg / h·m³. 3 The system adaptively adjusts based on real-time monitored temperature field data. When the temperature uniformity index drops below the threshold, the system automatically activates the auxiliary steam injection device to increase steam supply in areas with lower temperatures; when the temperature in a certain area is too high, the steam supply in that area is reduced to ensure overall temperature field uniformity. When the system detects that the mode switching conditions meet the requirements to switch from the overall mode to the individual mode, the control system first reduces the main steam pipeline supply to 25%. After the isolation device completes the mode switch, the steam supply system of each independent steam curing unit is then turned on, and the steam supply is adjusted to 22 kg / h·m³. At the same time, the temperature curve is adjusted accordingly to the optimal parameters in the individual steam curing mode to adapt to the individual steam curing requirements of the tube segments.

[0106] To facilitate understanding of the above-mentioned technical solution of the present invention, the following detailed description is based on a segment production line of a large-scale bay area submarine tunnel project:

[0107] A certain large-scale bay area undersea tunnel project adopts the shield tunneling method for construction. The segment factory adopts a 1+4 production line layout, that is, one production line is paired with four static curing lines.

[0108] like Figure 5 As shown, a digital tube segment intelligent control center was constructed during the implementation of this invention. This center monitors the data of the steam curing kilns in real time, including the number of kilns, the number of tubes being cured, and temperature indicators. This system allows for a clear understanding of the operating status of each steam curing kiln, ensuring that the temperature during the steam curing process is controlled within the optimal range. In the illustrated data, a total of 7 tube segments are being cured in the kiln. The system monitored a maximum temperature of 40.9°C, a minimum temperature of 37.0°C, and an average temperature of 38.3°C. It also displays the real-time temperature data for the heating zone (preheating stage), the constant temperature zone (constant temperature maintenance stage), and the cooling zone (cooling stage) of lines 1 to 4 in the kiln. This data provides accurate basic parameters for the steam curing control method of this invention.

[0109] like Figure 6As shown, the production line monitoring interface of the digital segment control center provides more detailed real-time monitoring data for the static area and production line. This interface clearly displays the number of segments, temperature, steam valve status, and temperature and humidity conditions for each production line. The system also displays the time-varying trends of the static stop zone temperature and the heating zone temperature in chart form, allowing operators to intuitively understand the temperature change patterns in each area and thus optimize the steam curing parameter settings.

[0110] like Figure 3 As shown, the segment production process begins with bending and cutting the reinforcing bars, followed by the fabrication of the reinforcing cage. The completed reinforcing cage must pass inspection before installation, followed by another inspection and acceptance. Simultaneously, the mold-making process begins, involving mold cleaning, application of release agent, and mold inspection. After the reinforcing cage is installed and accepted, concrete production begins: mixing is done based on the raw materials, and the concrete is poured after passing inspection. Following pouring, the process involves finishing, curing in a kiln, and demolding. After demolding, the segments are inspected, then water-cured for 7 days, and finally stored and transported to the construction site. The molds are cleaned, coated with release agent, and inspected after each demolding to prepare for the next production cycle. The curing kiln uses a fully tie-rod structure, allowing individual or multiple molds to be moved to meet the production needs of different mold numbers for ultra-large segments.

[0111] In this project, the segment steam curing control method of the present invention first acquires the mix proportion data of segments with different impermeability grades, then uses a multi-point temperature and humidity sensor array to monitor the hydration heat release and identify key hydration time nodes; subsequently, a differentiated steam curing parameter set is determined. During production, production plan data and kiln loading sequence information are acquired first, and the optimal steam curing mode is automatically selected; then, energy utilization rate and temperature uniformity are calculated based on the thermofluid boundary layer theory; finally, when the conditions are met, the tie rod mechanism is controlled to push the mold to move, completing the steam curing mode switch. By applying the segment steam curing control method of the present invention, this project achieved an energy utilization rate increase of approximately 18%, a temperature uniformity index increase from 85% to 92.6%, and a segment impermeability performance qualification rate increase from 93% to 99.5% during the segment production process, providing a strong guarantee for ensuring the long-term safety and durability of the tunnel project.

[0112] like Figure 4 As shown, according to another embodiment of the present invention, a tube curing control system for a universal tube curing kiln is also provided, the tube curing control system for the universal tube curing kiln includes:

[0113] Parameter setting unit 1 is used to determine the key hydration time node sequence of segments with different permeability grades under different steam curing modes based on the segment permeability grade information and concrete mix data, and to establish a differentiated steam curing parameter set for segments with different permeability grades under individual steam curing mode and overall steam curing mode.

[0114] The mode control unit 2 is used to select the current steam curing mode based on the segment entry sequence information and the differentiated steam curing parameter set, calculate the energy utilization rate and temperature uniformity of the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode switching conditions to complete the switching of different steam curing modes.

[0115] The regulating unit 3 is used to adjust the steam supply and steam curing temperature based on the current steam curing mode and mode switching conditions to ensure the quality of the tube segment steam curing.

[0116] 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 within the protection scope of the present invention.

Claims

1. A segment autoclaving control method for a segment universal autoclave, characterized by, The method comprises the following steps: S1, based on the pipe piece impermeability grade information and the concrete mix data, determine the key hydration time node sequence of each impermeability grade pipe piece under different steam curing modes, and establish the differential steam curing parameter set under the separate steam curing mode and the overall steam curing mode; specifically including: S11, according to the pipe piece impermeability grade information and the concrete mix data, obtain the material characteristic parameter matrix of pipe pieces of different impermeability grades, and analyze the pore characteristics of the pipe pieces to obtain pore distribution characteristic data; S12, using a multi-point temperature and humidity sensor array, monitor the hydration heat release curve and temperature field distribution of pipe pieces of each impermeability grade under the separate steam curing mode and the overall steam curing mode respectively, and determine the key hydration time node sequence under different steam curing modes; S13, according to the key hydration time node sequence and the pore distribution characteristic data, calculate the weight coefficients of different steam curing stages, and generate the differential steam curing parameter set for pipe pieces of different impermeability grades in combination with the reference steam curing parameters; S2, according to the pipe piece kiln entry sequencing information, select the current steam curing mode in combination with the differential steam curing parameter set, calculate the energy utilization rate and temperature uniformity under the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode conversion condition to complete the switching of different steam curing modes; specifically including: S21, obtain the current production plan data and the pipe piece kiln entry sequencing information, calculate the expected hydration heat distribution under different combination schemes according to the pipe piece impermeability grade distribution and the kiln entry timing in combination with the differential steam curing parameter set, and select the current steam curing mode; S22, based on the thermal fluid boundary layer theory, real-time monitor the steam flow characteristics and the heat exchange efficiency of the pipe piece surface through the multi-point temperature and humidity sensor array, calculate the energy utilization rate and temperature uniformity under the current steam curing mode to determine the mode conversion condition; S23, when the mode conversion condition is met, issue an instruction according to the pipe piece position distribution in the curing kiln to control the pull rod mechanism to push the mold to move, so as to complete the switching of different steam curing modes; S3, based on the current steam curing mode and the mode conversion condition, adjust the steam pipe supply amount and the steam curing temperature to ensure the pipe piece steam curing quality; The calculation of the energy utilization rate and the temperature uniformity under the current steam curing mode to determine the mode conversion condition comprises: based on the real-time monitoring data of the multi-point temperature and humidity sensor, calculating the Reynolds number and the Prandtl number of the steam fluid in the steam curing kiln to determine the boundary layer flow characteristics; according to the boundary layer flow characteristics, calculating the convective heat transfer coefficient and the thermal resistance value between the inner wall of the steam curing kiln and the pipe piece surface; analyzing the flow path of the steam under the current steam curing mode, calculating the Nusselt number of the pipe piece surface to determine the heat transfer coefficient; through the product of the heat transfer coefficient and the temperature gradient, calculating the effective heat transfer rate and the heat loss rate per unit time to obtain the energy utilization rate; according to the maximum difference and the standard deviation of the temperature of each measuring point, calculating the temperature uniformity index under the current steam curing mode; when the energy utilization rate is lower than the preset efficiency value or the temperature uniformity exceeds the preset fluctuation range, the mode conversion is determined.

2. A segment steam curing control method for a segment universal steam curing kiln according to claim 1, characterized in that, The obtaining of the material characteristic parameter matrix of pipe pieces of different impermeability grades according to the pipe piece impermeability grade information and the concrete mix data, and the analysis of the pore characteristics of the pipe pieces to obtain the pore distribution characteristic data comprises: S111, based on the concrete mix proportion, the water-binder ratio and mineral admixture content of different impermeability grade pipe pieces are extracted, and a material characteristic parameter matrix is constructed; S112, using a permeability tester, a gradient water pressure is applied to different impermeability grade pipe piece test blocks, the relationship between penetration depth and time is recorded, and the permeability coefficient and critical penetration pressure value are obtained through data fitting; S113, according to the permeability coefficient and critical penetration pressure value, combined with the material characteristic parameter matrix, the pore size distribution and porosity of different impermeability grade pipe pieces are calculated by capillary bundle method, and a pore distribution characteristic data table is established.

3. The segment steam curing control method for a segment universal steam curing kiln according to claim 1, wherein, The use of a multi-point temperature and humidity sensor array in a separate steam curing mode and a whole steam curing mode respectively monitors the hydration heat release curve and temperature field distribution of each impermeability grade pipe piece, and determines the key hydration time node sequence under different steam curing modes, which includes: S121, in the separate steam curing mode, the temperature field distribution and hydration heat release rate of a single pipe piece are monitored by using a multi-point temperature and humidity sensor array, the initial setting time point, final setting time point, hydration peak time point and strength standard time point are identified, and a first hydration time node sequence is formed; S122, in the whole steam curing mode, the temperature field distribution and hydration heat release curve of multiple pipe pieces are synchronously monitored by a distributed temperature and humidity sensor network, the group hydration synchronization point, temperature equalization point and whole strength standard point are identified, and a second hydration time node sequence is formed; S123, according to the first hydration time node sequence and the second hydration time node sequence, the hydration heat release peak time difference and temperature difference of the same impermeability grade pipe piece under different steam curing modes are calculated, and a key hydration time node sequence is generated.

4. The segment steam curing control method for a segment universal steam curing kiln according to claim 3, wherein The first hydration time node sequence includes: Based on the collected single pipe piece temperature data, the temperature change rate between adjacent two sampling time points is calculated, a temperature change rate time sequence is generated, and a temperature change rate curve is obtained by smoothing processing; The slope sign change point of the temperature change rate curve is detected, when the slope changes from negative to positive and the change rate is greater than a preset first threshold value, the time point is determined as the initial setting time point; When the temperature change rate reaches a preset proportion of the maximum value for the first time, it is marked as the rapid hydration starting time point; when the temperature change rate reaches the maximum value, it is marked as the hydration peak time point; When the temperature change rate drops from the peak value to a preset percentage of the maximum value and the change rate of the continuous multiple sampling points is less than a preset second threshold value, it is marked as the hydration termination critical time point; The determined different time points are arranged in time sequence to form the first hydration time node sequence.

5. The segment steam curing control method for a segment universal steam curing kiln according to claim 3, wherein The second hydration time node sequence includes: According to the temperature data of each pipe piece in the same steam curing cycle, the pipe pieces are grouped according to their spatial positions in the steam curing kiln, and each group contains several pipe pieces; The average temperature and temperature standard deviation of each group of pipe pieces at the same time point are calculated, and a standard deviation curve with time is drawn; When the temperature standard deviation of all groups is simultaneously less than a preset temperature deviation value and lasts for more than a preset time, the starting point of the time period is determined as the group hydration synchronization point; The temperature gradient between different position measuring points in the steam curing kiln is calculated, and when the maximum temperature gradient value is less than the preset gradient threshold and lasts for more than a preset duration, the starting point of the time period is marked as a temperature equalization point; Based on the pre-established temperature-strength correspondence, when the calculated equivalent strength reaches the preset strength percentage of the design requirement, the time point is marked as an overall strength compliance point; The group hydration synchronization point, the temperature equalization point and the overall strength compliance point are arranged in time sequence to form a second hydration time node sequence.

6. The segment steam curing control method for a segment universal steam curing kiln according to claim 1, wherein, The weight coefficients of different steam curing stages are calculated based on the key hydration time node sequence and the pore distribution characteristic data, and the differential steam curing parameter set for different impermeability grade pipes is generated in combination with the benchmark steam curing parameters, which includes: S131, the pipe steam curing process is divided into a preheating and warming-up stage, a constant temperature maintaining stage and a cooling-down stage, an analytic hierarchy process is used to establish a steam curing stage evaluation system, the pore distribution characteristic data and the key hydration time node sequence are used as judgment criteria to construct a judgment matrix; S132, the weight coefficients of different steam curing stages on the impermeability of the pipes are obtained by calculating the eigenvalues and eigenvectors of the judgment matrix; S133, based on the benchmark steam curing parameters and the weight coefficients, the temperature setting value, the steam supply amount and the duration of different impermeability grade pipes under different steam curing modes are calculated respectively, and the parameter difference rate, the conversion sensitivity and the adaptive range between the two modes are recorded to form the differential steam curing parameter set.

7. A segment autoclave control system for a segment universal autoclave for implementing the segment autoclave control method according to any one of claims 1 to 6, characterized by The system comprises: A parameter setting unit is configured to determine the key hydration time node sequence of each impermeability grade pipe under different steam curing modes based on the impermeability grade information of the pipes and the concrete mix data, and to establish the differential steam curing parameter set under the separate steam curing mode and the overall steam curing mode; specifically including: obtaining the material characteristic parameter matrix of different impermeability grade pipes according to the impermeability grade information of the pipes and the concrete mix data, and analyzing the pore characteristics of the pipes to obtain the pore distribution characteristic data; using a multi-point temperature and humidity sensor array to monitor the hydration heat release curve and the temperature field distribution of each impermeability grade pipe under the separate steam curing mode and the overall steam curing mode, respectively, to determine the key hydration time node sequence under different steam curing modes; calculating the weight coefficients of different steam curing stages based on the key hydration time node sequence and the pore distribution characteristic data, and generating the differential steam curing parameter set for different impermeability grade pipes in combination with the benchmark steam curing parameters; The mode control unit is used to select a current steam curing mode according to the segment entry sequence information, combine the differentiated steam curing parameter set, calculate the energy utilization rate and temperature uniformity under the current steam curing mode based on the thermal fluid boundary layer theory, and determine the mode conversion condition to complete the switching of different steam curing modes; specifically including: obtaining the current production plan data and segment entry sequence information, calculating the expected hydration heat distribution under different combination schemes according to the segment impermeability grade distribution and entry timing, combining the differentiated steam curing parameter set, selecting the current steam curing mode; based on the thermal fluid boundary layer theory, the steam flow characteristics and the heat exchange efficiency of the segment surface are monitored in real time through a multi-point temperature and humidity sensor array, the energy utilization rate and temperature uniformity under the current steam curing mode are calculated to determine the mode conversion condition; when the mode conversion condition is met, an instruction is issued according to the segment position distribution in the curing kiln to control the pull rod mechanism to move the mold to complete the switching of different steam curing modes; The execution adjustment unit is used to adjust the steam pipeline supply amount and the steam curing temperature based on the current steam curing mode and the mode conversion condition to ensure the segment steam curing quality; The calculation of the energy utilization rate and the temperature uniformity under the current steam curing mode to determine the mode conversion condition includes: based on the real-time monitoring data of the multi-point temperature and humidity sensor, the Reynolds number and the Prandtl number of the steam fluid in the steam curing kiln are calculated to determine the boundary layer flow characteristics; according to the boundary layer flow characteristics, the convective heat transfer coefficient and the thermal resistance value between the inner wall of the steam curing kiln and the segment surface are calculated; the flow path of the steam under the current steam curing mode is analyzed, the Nusselt number of the segment surface is calculated, and the heat transfer coefficient is determined; the effective heat transfer rate and the heat loss rate per unit time are calculated through the product of the heat transfer coefficient and the temperature gradient to obtain the energy utilization rate; according to the maximum difference and the standard deviation of the temperature of each measuring point, the temperature uniformity index under the current steam curing mode is calculated; when the energy utilization rate is lower than the preset efficiency value or the temperature uniformity exceeds the preset fluctuation range, the mode conversion is determined.

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