CN112987813A - Water cooling optimization control method for lining concrete with different strengths - Google Patents
Water cooling optimization control method for lining concrete with different strengths Download PDFInfo
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Abstract
The invention provides an optimal control method for cooling water through lining concrete with different strengths, which can objectively and accurately obtain optimal control water cooling time, water temperature and temperature drop rate suitable for the lining concrete with different strengths, and carries out water cooling on a lining structure based on the optimal control water cooling time, water temperature and temperature drop rate, thereby scientifically and reasonably realizing temperature control and crack prevention. The method for controlling the temperature by water cooling comprises the following steps: step 1, obtaining water cooling temperature control data of lining concrete; step 2, calculating water cooling time T according to the thickness of the lining concreted2.0H +0.04C + 3.0; step 3, calculating water cooling optimal control water temperature T according to the lining concrete thicknesswy17.22-0.17 xc; step 4, calculating and optimally controlling the temperature reduction rate (V) according to the thickness of the lining concretec0.14 xc-2.16; step 5, cooling time T according to waterdOptimally controlling water temperature TwyOptimally controlling the temperature drop rate [ V ]cOptimizing lining concrete water cooling measures.
Description
Technical Field
The invention belongs to the technical field of concrete temperature control and crack prevention, and particularly relates to a water-through cooling optimization control method for lining concrete with different strengths.
Background
Large-volume concrete such as a gravity dam and the like is embedded with a cooling water pipe for water cooling, and cooling water or low-temperature river water is introduced at the initial stage, so that the highest temperature of the concrete is reduced; in the middle stage, river water can be introduced for cooling, and the temperature difference between the inside and the outside can be controlled. The initial water cooling is carried out, the time is determined by calculation, 10 to 20 days can be taken, and the difference between the concrete temperature and the water temperature is not more than 25 ℃. The water cooling is carried out in the middle period, preferably about 1-2 months, and the difference between the water temperature and the concrete internal temperature should not exceed 20-25 ℃. The daily temperature reduction is not more than 1.0 ℃. Since the concrete expands during the temperature rise period, the maximum temperature of the concrete is preferably reduced as much as possible, and the initial water temperature is preferably reduced as much as possible under allowable conditions. In the middle stage, the temperature drop stage is the stage in which the water temperature is too low and the temperature drop speed is too fast, which may cause early-stage low-strength concrete cracks and may also cause local cracks due to too large temperature gradient of the concrete around the pipe, so the water temperature and thus the temperature drop rate must be controlled.
According to the research on the influence of the initial water-cooling temperature of the high-concrete arch dam on the concrete around the water pipe in the simulated concrete pouring process: for old concrete at the lower part (layer) of the water pipe, the temperature of the concrete is higher (20 ℃) before the water pipe is cooled by water, when the water pipe is cooled by the water, the concrete at the periphery of the water pipe is quickly close to the water temperature from the higher temperature, the closer to the water pipe, the faster the temperature drop speed is, a larger gradient of temperature drop amplitude is formed at the periphery of the water pipe, and the lower the water temperature is, the larger the gradient of the temperature drop amplitude is; the newly poured concrete on the upper part of the water pipe is cooled by water while being poured, and the concrete around the water pipe is kept at a temperature close to the water temperature without being raised to a high temperature (the initial warehousing temperature). Although the distance from the water pipe is different, the temperature and the temperature gradient of the parts are kept unchanged and do not change greatly. The shrinkage deformation is generated by temperature reduction, the deformation is not uniform due to non-uniform temperature reduction amplitude, and self-restraint is generated, so that the tensile stress is generated by old concrete at the lower part of the water pipe due to the non-uniform temperature reduction amplitude, and the tensile stress is not large due to the fact that newly poured concrete at the upper part of the water pipe does not have an obvious temperature reduction process. Therefore, the water temperature (namely the temperature difference with the internal concrete) of the water-through cooling water of the mass concrete such as the multi-layer pouring dam is controlled by not generating temperature cracks around the lower-layer old concrete pipe, and the allowable water temperature difference and the temperature drop speed are smaller.
The lining is a structure (figure 1) widely adopted in civil engineering, hydraulic tunnels and other relevant regulations have no provisions on control of water cooling time, water temperature, temperature reduction rate and the like of lining concrete. In the engineering construction, the concrete gravity dam (or arch dam) design, hydraulic concrete construction and other standard regulations are only required to be adopted: the temperature difference between the dam body concrete and cooling water is not more than 20-25 ℃, the water is used for cooling for 10-20 days, and the daily temperature reduction is not more than 1.0 ℃.
Practical research finds that lining structures have different strength, different heat productivity and different internal temperature, and different water cooling time, water temperature difference capable of being born, temperature reduction rate and the like, so that optimization of water cooling parameters also needs to be adjusted correspondingly according to the strength, but at present, no method for scientifically adjusting and controlling parameters of water cooling time, water temperature, temperature reduction rate and the like of lining concrete according to the strength exists.
Disclosure of Invention
The invention aims to solve the problems and provide a water cooling optimization control method for lining concrete with different strengths, which can objectively and accurately obtain the optimized control water cooling time, water temperature and temperature drop rate suitable for the lining concrete with different strengths, and can carry out water cooling on a lining structure based on the optimization control water cooling time, water temperature and temperature drop rate so as to scientifically and reasonably realize temperature control and crack prevention.
In order to achieve the purpose, the invention adopts the following scheme:
as shown in FIG. 2, the present invention provides a water cooling optimization control method for lining concrete with different strengths, which is characterized by comprising the following steps:
Td2.0H +0.04C +3.0 (formula 1)
In the formula: h is the thickness of the lining concrete; c, designing age strength grade for the lining concrete 90 d;
step 3, calculating water cooling optimal control water temperature T according to the lining concrete thicknesswy：
Twy17.22-0.17 × C (formula 2)
Step 4, calculating and optimally controlling the temperature reduction rate (V) according to the thickness of the lining concretec】：
【Vc0.14 × C-2.16 (formula 3)
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: in the water cooling measure taken in step 5, the water cooling time is controlled to be not less than Td。
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: in the water cooling measure taken in step 5, the water cooling time is controlled to be Td～(Td+0.5 d).
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: in the water cooling measures taken in step 5, the water temperature should be controlled to be (T)wy－0.5℃)～(Twy+1 ℃ range.
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: at step 5 adoptIn the water cooling measures, the temperature reduction rate should be controlled not to exceed Vc】。
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: adopting a control processing device to execute the steps 2 to 4, and calculating the water cooling time TdWater temperature TwyTemperature drop rate [ V ]c】。
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: the control processing device is also adopted to execute the step 5 according to the cooling time T of the waterdWater temperature TwyTemperature drop rate [ V ]cAnd determining water cooling measures, and controlling a water cooling system to execute the water cooling measures to carry out water cooling maintenance on the lining concrete.
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: and (3) executing the step (1) by adopting a control processing device, and inputting and storing the water-feeding cooling temperature control data of the lining concrete by a user according to the prompt.
Preferably, the optimal control method for water cooling of lining concrete with different strengths provided by the invention can also have the following characteristics: and the control processing device is also adopted to display the input information, the calculation result and the determined water cooling measures according to the user instruction.
In addition, the step 2 calculates the water cooling optimization control time T according to the structural strength of the liningdThe calculation formula 1 is obtained by taking lining concrete of different structures such as 3 large engineering flood spillways, power generation holes and the like of Xiluodi, white Crane beach, Wudongde as an example, adopting a three-dimensional finite element method to carry out simulation calculation to obtain the water cooling temperature control characteristics and the rules of the lining concrete, and then carrying out statistical analysis. The method comprises the following steps:
1) analysis of control parameters for water cooling opportunity
The thin-wall lining structure is small in thickness and only cooled by water in one period, and the aim is to reduce the highest internal temperature and control the internal surface temperature difference. The cooling water pipe is covered with concrete at the beginning of water coolingI.e. initially cooled by water. Therefore, the parameter to be determined for the cooling time is the water passage time Td. The water cooling age must be more than TmaxAge of onset TmdAnd maximum internal surface temperature difference delta TmaxAge of onset Δ Tmd. Taking into account the cooling time T of the waterdGreater than Δ TmdThe temperature control and crack prevention still have small effect, the increase of the temperature difference of the inner surface caused by stopping the water cooling cannot be allowed, and TdShould be greater than Δ TmdFor a slightly greater amount of time. However, the water passing time is not longer in consideration of the economical efficiency.
Therefore, the Delta T of lining concrete with different thicknesses and different strengths is calculated through finite element method simulationmdThe water cooling age T can be obtained by properly increasing the margin timedThe calculation formula of (2).
2) Concrete simulation calculation for lining structure of Xiluodi flood discharge tunnel
The different structural sections of the stream ferry spillway tunnel are used for simulation calculation of 43 schemes, and the scheme is shown in table 1. Wherein 1-27 are the pressure sections of the flood discharge tunnel; 28-40 are non-pressure sections of the flood discharge tunnel; 41-43 are the silica powder concrete of the tail section of the dragon falling. The lining concrete T is not influenced by some factorsmax、 △TmaxAge of appearance TmdAnd Δ TmdTherefore, it is not listed. In the table, the concrete strength grades are all 90d design strength.
TABLE 1 Rabbit crossing flood discharge tunnel lining concrete Tmax、△TmaxAge of appearance TmdAnd Δ Tmd
3) White crane beach lining concrete Tmax、△TmaxAge of appearance
Calculating concrete temperature control lining with flood discharge hole and power generation hole of white crane beach hydropower stationThe scheme is developed as a basis, and other changes are explained in a remark column. Wherein, 1-9 are diversion tunnels; 10-17 are flood discharging holes. The lining concrete T is not influenced by some factorsmax、△TmaxAge of appearance TmdAnd Δ TmdTable 2 shows only the thickness and strength influence items in the case of water cooling.
TABLE 2 white crane beach underground water work lining concrete Tmax、△TmaxAge of appearance TmdAnd Δ Tmd
| Serial number | Thickness (m) | Strength grade | Tmd(d) | △Tmd(d) | Remarks for |
| 1 | 2.5 | C30 | 5 | 6.25 | Side wall, |
| 2 | 2.5 | C40 | 4.5 | 5.75 | Floor, summer |
| 3 | 6 | C30 | 8 | 10 | Mid-partition wall in summer |
| 4 | 2.5 | C30 | 5 | 6.25 | Side walls, |
| 5 | 2.5 | C40 | 4.75 | 6 | Floor, winter |
| 6 | 1.5 | C30 | 2.75 | 3.75 | Side wall, summer |
| 7 | 1.5 | C40 | 2.5 | 3.5 | Floor, summer |
| 8 | 1.1 | C30 | 2.25 | 3.75 | Side wall, summer |
| 9 | 1.1 | C40 | 2 | 3.75 | Floor, |
| 10 | 1.0 | C40 impact mill | 1.75 | 3.75 | Floor, summer |
| 11 | 1.0 | C40 |
2 | 3.75 | Side wall, summer |
| 12 | 1.0 | C40 impact mill | 1.75 | 3.5 | Floor, winter |
| 13 | 1.0 | C40 impact mill | 1.75 | 3.5 | Side walls, |
| 14 | 1.5 | C40 impact mill | 2.5 | 3.75 | Side wall, |
| 15 | 1.0 | C60 impact mill | 2.25 | 3.75 | Side wall, summer |
| 16 | 1.0 | C60 impact mill | 2.0 | 3.75 | Floor, summer |
| 17 | 1.5 | C60 impact mill | 3 | 4.25 | Side wall, summer |
4) Wudongde lining concrete Tmax、△TmaxAge of appearance
The calculation is developed on the basis of a Wudongde flood discharge tunnel and power generation tunnel lining concrete temperature control scheme, and other changes are explained in a remark column. Wherein 1-19 are slow slope sections of the flood discharge tunnel; 20-22 are steep slope sections of the flood discharge tunnel; 23-24 are pressure sections of the flood discharge tunnel. 25-26 are voltage sections of the power generation holes; 27-28 are non-pressure sections of the power generation holes. In the table, the concrete strength grades are all 90d design strength. The results are summarized in Table 3.
TABLE 3 Udongde underground hydraulic lining concrete Tmax、△TmaxAge of appearance TmdAnd Δ Tmd
5) Delta T of lining concretemdWater-feeding cooling age TdStatistical formula
Delta T in tables 1 to 3maxAge Δ TmdThe relation between the thickness and the strength of the lining concrete is obtained by statistical analysis
△Tmd2.0H +0.04C +2.0 (formula 4)
According to the analysis, the cooling time by introducing water in the engineering is preferably properly longer than Delta TmaxAge Δ TmdTherefore, 1d is added to the formula 4 to obtain the formula 1.
Td2.0H +0.04C +3.0 (formula 1)
Calculating water cooling optimization control water temperature T according to lining structure strength in step 3wyThe calculation formula 2 is that the three-dimensional finite element method is adopted to carry out the flood discharge tunnel engineering of the giant hydropower station such as the Xiluodi, the white Crane beach, the Wudongde and the like, and the concrete with different strength and thickness of the gate tunnel type section is carried out under the conditions of different water cooling water temperaturesAnd (3) carrying out simulation calculation on temperature and temperature stress, and sorting and analyzing the temperature control and anti-cracking effect of the lining concrete in the whole process so as to obtain the optimal water cooling water temperature with different strengths on the principle of maximizing the anti-cracking safety coefficient in the whole process. For example, a 1.0m thickness sidewall C adopting a structure (FIG. 1)9030-strength concrete, calculating the crack resistance safety coefficient K of the whole lining concrete process through simulation calculation of different water temperatures Tw at 8-22 ℃ in the table 4, and arranging two curing periods with the minimum K value and K in winter1、K2Then make K1、K2With the temperature T of the waterwSee fig. 3. Due to K1With TwIncrease, K2With TwThe point of intersection of the two curves is the water temperature T which can obtain the maximum safety coefficient of crack resistance in the whole processwy. The optimal water cooling temperature of the lining concrete with different strengths is shown in the table 5, and the data are analyzed and researched to obtain the optimal water temperature TwyEquation 2 is calculated.
TABLE 41.0 m Lining C 9030 concrete water cooling characteristic values at different water temperatures
TABLE 5 optimal water cooling temperature for different strength lining concrete
In the step 4, the optimized control temperature drop rate [ V ] is calculated according to the structural strength of the liningcThe calculation formula 3 is that the temperature and temperature stress simulation calculation of the concrete with different strength of the cross section of the tunnel type 1.0m thickness under different water cooling water temperature conditions is carried out by adopting a three-dimensional finite element method, the temperature control anti-cracking effect of the lining concrete in the whole process is sorted and analyzed, the principle of maximizing the whole process anti-cracking safety coefficient is obtained, and the temperature reduction rate is optimized and controlled by different strength. For example, a 1.0m thickness sidewall C adopting a structure (FIG. 1)9030-strength concrete passing through 8-22 ℃ in Table 4Different water temperatures TwPerforming condition simulation calculation, solving the crack resistance safety coefficient K of the whole lining concrete process, and arranging the two maintenance periods with the minimum K value and the K value in winter1、K2Then make K1、K2Temperature T of waterwSee fig. 3. Due to K1With TwIncrease, K2With TwWhen the crack resistance coefficient is reduced, the maximum value of the crack resistance safety coefficient of the whole process is taken as the intersection point of the two curves, and the maximum value is called as the water cooling comprehensive optimization crack resistance safety coefficient KyThe water temperature is called the optimal control water temperature Twy. And KyThe corresponding water cooling temperature reduction rate is called as the optimized control temperature reduction rate [ V ]cThe water temperature difference is called as the optimal control water temperature difference delta Twy. For C 9030 concrete according to Table 4, fromyCorresponding optimization of water temperature TwyInterpolation to obtain TsdThe value is the optimized control temperature drop rate [ V ]cSummarizing optimal water cooling temperature drop rates [ V ] of lining concrete with different strengthscSee table 6 (only three common intensities are listed for illustration), then these data are analyzed and studied to obtain the optimized control of temperature drop rate [ V ]cEquation 3 is calculated.
TABLE 6 optimal allowable Rate of temperature drop for different Strength lined concrete
Action and Effect of the invention
The optimal control method for cooling the water by the lining concrete with different strengths provided by the invention has the advantages that:
(1) the method can be applied to any lining structure, and measures schemes and parameter optimization of water cooling and temperature control of lining concrete with different strengths are carried out.
(2) The method is scientific. Water cooling optimization control time TdThe water temperature difference and the temperature drop rate calculation formula scientifically reflect the influence of the thickness of the lining concrete structure on the water cooling effect, and comprehensively provide the optimization control parameters of the lining concrete structure.
(3) According to the formulas 1-3, the optimal control time, the water temperature difference and the temperature reduction rate of water cooling of the lining concrete with different strengths can be quickly and conveniently obtained, the better effect of temperature control and crack prevention of the lining concrete is obtained, and the temperature control and crack prevention are scientifically and reasonably realized.
Drawings
FIG. 1 is a structural section view (dimension unit: m in the figure) of a tunnel lining concrete of a hydraulic tunnel with a cave shape;
FIG. 2 is a flow chart of the optimal control method for cooling water by lining concrete with different strengths according to the present invention;
FIG. 3 shows a graph C according to the present invention 9030 concrete curing period K with different thickness1And winter K2Water is introduced for cooling water temperature TwA relationship diagram of (1);
FIG. 4 is a cross-sectional view of a lining with a 0.8m thickness of a pressure section of the Wudongde flood discharge tunnel according to the invention;
FIG. 5 is a sectional view of a B-type 1.0m thick lining of a pressureless gentle slope section of the Wudongde spillway tunnel according to the invention.
Detailed Description
The concrete implementation of the water cooling optimization control method for lining concrete with different strengths, which is provided by the invention, is described in detail below by taking the flood discharge tunnel project of the Wudongde hydropower station as an example in combination with the attached drawings.
< Udongde hydropower station spillway tunnel engineering lining concrete temperature control data >
The Wudongde hydropower station mainly generates electricity and has the functions of flood control, shipping, sand blocking and the like. Installed capacity 10200MW of power station. The dam is a concrete hyperbolic arch dam, and flood discharge adopts a mode that the dam body mainly discharges flood and the shore flood discharge hole is assisted. The three flood discharging holes are all of tunnel type tunnels with pressure holes and then door-connected holes, and each tunnel type tunnel comprises a water inlet, a pressure hole section, a working gate chamber, a non-pressure hole section, an outlet section and an energy dissipation plunge pool, and the outlets adopt trajectory jet energy dissipation. The pressure tunnel of the flood discharge tunnel has a circular section (figure 4), an inner diameter of 14m, lining thicknesses of 0.8m and 1m, surrounding rocks of II and III types respectively and lining concrete C 9030. The section of the non-pressure hole section is in an urban portal shape, and the size of the non-pressure hole section after lining is 14m multiplied by 18 m. The design of the flood discharge tunnel gentle slope section is provided with three lining thickness structural sections of 0.8m, 1.0m and 1.5mThe rock classes around the tunnel are II, III and IV surrounding rocks respectively. The bottom plate and the side wall are C9035 impact-resistant and wear-resistant concrete with crown arch of C 9030 concrete. The steep slope section is also designed with two lining thickness sections of 0.8m and 1.0m, and the bottom plate and the side wall are C9040 impact-resistant and wear-resistant concrete with crown arch of C 9030 concrete. The section of the lining structure with three thicknesses of the flood discharge tunnel non-pressure section (the gentle slope section and the steep slope section) is shown in figure 5 (the section is the same after lining, and the structure thickness is changed only).
Carry out temperature control to the concrete at the overall process of concrete placement and maintenance, avoid the concrete fracture, the design requires the temperature control measure to include:
(1) quality control and mix proportion optimization of concrete raw material
The water content of the concrete fine aggregate is controlled to be below 6%, and the fluctuation range of the water content is less than 2%. The mixing proportion of the concrete is optimized, and the using amount of concrete cementing materials is reduced; the construction management is enhanced, the construction process is improved, the concrete performance is improved, and the concrete anti-cracking performance is improved. On the premise of meeting the concrete strength, durability, workability and concrete pouring quality required by design, the concrete aggregate gradation is improved by adopting larger aggregate particle size as much as possible after the approval of a manager.
(2) Reasonably arranging concrete construction procedure and construction progress
The reasonable arrangement of concrete construction procedures and construction progress is one of the main measures for preventing foundation from penetrating cracks and reducing surface cracks. The concrete construction procedure and the construction progress should be reasonably arranged, and the construction management level should be improved in an effort.
(3) Controlling concrete internal maximum temperature
The necessary temperature control measures should be taken so that the maximum temperature does not exceed the design allowable maximum temperature (table 7). The effective measures include concrete pouring temperature reduction, cementing material hydration heat temperature rise reduction, initial water cooling and the like. The concrete production system provides mixed concrete meeting the outlet temperature requirement. The contractor is responsible for controlling the temperature of concrete during the concrete transportation, warehousing and casting and curing after leaving the machine outlet. According to the analysis of computational results, the concrete pouring temperature of the gentle slope section of the flood discharge tunnel of the Wudongde hydropower station is recommended to be controlled according to the table 7. And if the measured temperature can not meet the maximum temperature allowed by the design, the buried cooling water pipe needs to be filled with water for cooling.
(4) Reasonably controlling the thickness of the pouring layer and the interval period between layers
When concrete is poured on each part, if the poured concrete pouring temperature cannot meet related requirements, a supervisor is immediately informed, treatment is carried out according to the instruction of the supervisor, and effective measures are immediately taken to control the concrete pouring temperature.
Table 7 units of maximum temperature and casting temperature allowed during construction of flood tunnel lining concrete: c
| Month of the year | 12.1 |
2. 11 month | 3. 10 month | 4. 9 |
5 to 8 months |
| Allowable maximum temperature | 40 | 41 | 42 | 43 | 44 |
| Allowable casting temperature | Naturally put into storage | Naturally put into |
18 | 20 | 22 |
<Example one>Pressure section 0.8m thickness C of flood discharge tunnel90Water cooling optimization control for 30-lining concrete
A lining structure section with the thickness of 0.8m of the pressure section of the flood discharge tunnel is shown in figure 4, and annular construction parting seams, class II surrounding rocks are arranged every 12m along the axial direction of the flood discharge tunnel. Pouring concrete by stages 2: bottom arch first and top arch last. The optimized control of water cooling for pouring top arch lining concrete is introduced.
As shown in fig. 2, the method for optimally controlling the water cooling of the thin-wall lining concrete with different strengths provided by this embodiment includes the following steps:
The basic data of the Wudongde hydropower station flood discharge tunnel are as described above, the flood discharge tunnel is a level 1 building, the flood discharge flow rate is high, and the temperature control and crack prevention of the lining concrete are very important. According to the design requirements, the casting temperature is controlled to be less than or equal to 22 ℃ in the casting process of 5-8 months in a high-temperature season, and temperature control measures such as water cooling are adopted. The highest temperature is controlled to be less than or equal to 44 ℃.
Calculated from equation 1. Lining with pressed section H0.8 m and concrete C90Substituting 30 into formula 1 to calculate Td5.8 d. And 6d is taken as the actual engineering control.
Step 3, calculating water cooling optimal control water temperature T according to lining structure strengthwy：
Lining with pressed section H0.8 m and concrete C90Substituting 30 into formula 2 to calculate Twy12.12 ℃. The actual process control is used for preparing the product at 12-13 ℃.
Step 4, calculating and optimally controlling the temperature reduction rate (V) according to the structural strength of the liningc】：
Lining with pressed section H0.8 m and concrete C90Substituting 30 into formula 3 to calculate [ V ]c2.04 ℃/d. The actual process control prepares 2.0 ℃/d.
And 5, optimizing a water cooling and temperature control scheme of the concrete of the thin-wall lining structure, namely calculating water cooling time, water temperature and allowable temperature drop rate according to the design technical requirements and the above to further optimize the construction temperature control water cooling scheme.
According to the calculation and the design technical requirements, the scheme for optimizing the water cooling temperature control is determined as follows: the pouring temperature is less than or equal to 22 ℃, the single-row spacing of the water cooling water pipes is 1.5m, the water passing time is 6d, the water temperature is 12 ℃, and the temperature reduction rate is controlled according to 2.0 ℃/d.
The effect is as follows: for the scheme (pouring in 7 months and 1 day), a finite element method is adopted for simulation calculation, and the result is as follows: internal maximum temperature 32.74 ℃ occurred at 1.75 d; the maximum internal surface temperature difference occurs at 4d at 3.47 ℃; the temperature drop rate is 1.6 ℃/d. The maximum temperature is less than the design allowable value of 44 ℃, the temperature drop rate is less than the optimized control value of 2.0 ℃/d, and the water cooling time 6d (which is far less than the common 10-20 d and saves the temperature control cost) is just longer than the maximum internal temperature difference occurrence time 4 d. The minimum crack resistance safety coefficient reaches 1.71, which is far greater than the design requirement 1.5, and no temperature crack occurs. Namely: the highest temperature, the inner surface temperature difference and the temperature reduction rate are well controlled; the water cooling time is just optimized; the most economic and effective temperature control anti-cracking effect is obtained.
<Example two>1.0m thickness C of flood discharge tunnel slope-slowing section9035 lining concrete through water cooling optimization control
A B-shaped lining structure with the thickness of 1.0m in a slow slope section of the flood discharge tunnel is shown in figure 5, and the cross section of the tunnel is an urban portal-shaped cross section, i.e. type III surrounding rock. C9035 pouring the concrete by stages 2: the side wall is firstly arched and then is provided with a bottom plate. The optimized control of side wall lining concrete pouring water cooling is introduced.
As shown in fig. 2, the method for optimally controlling the water cooling of the thin-wall lining concrete with different strengths provided by this embodiment includes the following steps:
Calculated from equation 1. Lining B is 1.0m, C90Substituting 35 concrete into formula 1 to obtain Td6.4 d. The actual process program prepares 6.5 d.
Step 3, calculating water cooling optimal control water temperature T according to the thickness of the lining structurewy：
Lining B with C90Substituting 35 concrete H-1.0 m into formula 2 to calculate Twy11.27 ℃. The actual process program controlled preparation of 12 ℃.
Step 4, calculating and optimally controlling the temperature reduction rate (V) according to the thickness of the lining structurec】：
Form B is C90Substituting 35 concrete lining H-1.0 m into formula 3 to obtain Vc2.74 ℃/d. The actual process control prepares 2.7 ℃/d.
And 5, optimizing a water cooling temperature control scheme of the concrete of the lining structure, namely calculating water cooling time, water temperature and allowable temperature reduction rate according to the design technical requirements and the above steps, and further optimizing the construction temperature control water cooling scheme.
According to the calculation and the design technical requirements, the scheme for optimizing the water cooling temperature control is determined as follows: the pouring temperature is less than or equal to 22 ℃, the single-row spacing of the water cooling water pipes is 1.5m, the water passing time is 6.5d, the water temperature is 12 ℃, and the temperature reduction rate is controlled according to 2.7 ℃/d.
The effect is as follows: for the scheme (pouring in 7 months and 1 day), a finite element method is adopted for simulation calculation, and the result is as follows: internal maximum temperature 40.5 ℃ occurs at 2.5 d; the maximum internal surface temperature difference occurs at 4.25d at 3.75 ℃; the temperature drop rate is 1.8 ℃/d. The maximum temperature is less than the design allowable value of 44 ℃, the temperature drop rate is less than the optimized control value of 2.7 ℃/d, and the water cooling time of 6.5d (which is far less than the common 10-20 d and saves the temperature control cost) is just more than the maximum internal temperature difference occurrence time of 4.25 d. The minimum crack resistance safety coefficient reaches 1.77, which is far greater than the design requirement 1.5, and no temperature crack occurs. Namely: the highest temperature, the inner surface temperature difference and the temperature reduction rate are well controlled; the water cooling time is just optimized; the most economic and effective temperature control anti-cracking effect is obtained.
<EXAMPLE III>1.0m thickness C of flood discharge tunnel steep slope section90Optimization control of water cooling of 40-lining concrete
A lining structure with the thickness of 1.0m at a steep slope section of the flood discharge tunnel is shown in figure 5, a cross section of a shape of an urban cave, class III surrounding rocks and class C9040 impact-resistant and wear-resistant concrete. Pouring concrete by stages 2: the side wall is firstly arched and then is provided with a bottom plate. The optimized control of the concrete pouring water cooling of the side crown arch lining is introduced.
As shown in fig. 2, the method for optimally controlling the water cooling of the thin-wall lining concrete with different strengths provided by this embodiment includes the following steps:
the basic data of the Wudongde hydropower station flood discharge tunnel are as described above, the flood discharge tunnel is a level 1 building, particularly the flood discharge velocity of a steep slope section is high, and the temperature control and crack prevention of the lining concrete are very important. According to the design requirements, the casting temperature is controlled to be less than or equal to 22 ℃ in the casting process of 5-8 months in a high-temperature season, and temperature control measures such as water cooling are adopted. The highest temperature is controlled to be less than or equal to 44 ℃.
Calculated from equation 1. C is to be90Substituting the value of H1.0 m for the concrete lining of 40 m into the formula 1 to calculate Td6.6 d. The actual process program prepares 7.0 d.
Step 3, calculating water cooling optimal control water temperature T according to the thickness of the lining structurewy：
C is to be90Substituting the value of H1.0 m in the 40 concrete lining into the formula 2 to calculate Twy10.42 ℃. The actual process control prepares 11 ℃.
Step 4, calculating and optimally controlling the temperature reduction rate (V) according to the thickness of the lining structurec】：
C is to be90Substituting the value of H1.0 m in the concrete lining of 40 m into the formula 3 to calculate Vc3.44 ℃/d. The actual process control prepares 3.4 ℃/d.
and according to the design technical requirements and the calculation of the water cooling time, the water temperature and the allowable temperature drop rate, the construction temperature control water cooling scheme is further optimized.
According to the calculation and the design technical requirements, the scheme for optimizing the water cooling temperature control is determined as follows: the pouring temperature is less than or equal to 22 ℃, the single-row spacing of the water cooling water pipes is 1.5m, the water passing time is 7.0d, the water temperature is 11 ℃, and the temperature reduction rate is controlled according to 3.4 ℃/d.
The effect is as follows: for the scheme (pouring in 7 months and 1 day), a finite element method is adopted for simulation calculation, and the result is as follows: internal maximum temperature 40.65 ℃ occurs at 2.5 d; the maximum internal surface temperature difference occurs at 4.25d at 3.65 ℃; the temperature drop rate was 2.6 ℃/d. The maximum temperature is less than the design allowable value of 44 ℃, the temperature drop rate is less than the optimized control value of 3.4 ℃/d, and the water cooling time of 7.0d (which is far less than the common 10-20 d and saves the temperature control cost) is more than the maximum internal temperature difference occurrence time of 4.25 d. The minimum crack resistance safety coefficient reaches 1.75, which is far greater than the design requirement 1.5, and no temperature crack occurs. Namely: the highest temperature, the inner surface temperature difference and the temperature reduction rate are well controlled; the water cooling time is just optimized; the most economic and effective temperature control anti-cracking effect is obtained.
By combining the analysis, the water cooling time and the water temperature are calculated by adopting the formulas 1 to 3, the temperature drop rate is controlled, and the optimal temperature control anti-cracking effect can be obtained. The formula scientifically reflects the relationship between the lining structure strength and the temperature, time and temperature drop rate of water cooling, and achieves the aims of controlling the highest temperature and the maximum inner surface temperature difference in the concrete by water cooling, optimizing the temperature drop speed, maximizing the anti-cracking safety coefficient and maximizing the economic and temperature control benefits.
The above example results show that the method of the invention can be applied to any lining structure (including different civil engineering types, different structural forms, different strengths, different thicknesses and the like), can quickly calculate and obtain temperature control parameters to carry out water-through cooling and optimal control on lining concrete, and realizes water-through cooling, temperature control, anti-cracking and maximum optimization and economic benefits.
The method is scientific. The water cooling time, the water temperature and the temperature drop rate of the concrete with the lining structure are controlled and optimized, and the calculation formulas 1-3 comprehensively reflect the influence of main parameters such as the strength of the concrete structure with the lining structure.
And calculating control values of water cooling time, water temperature and temperature drop rate of the concrete with the lining structure according to formulas 1-3, optimizing reasonably, obtaining a maximum anti-cracking safety coefficient value, scientifically realizing the target of controlling the highest temperature and the maximum internal temperature difference of the concrete by water cooling, optimizing the temperature drop rate and maximizing the economic benefit.
The above embodiments are merely illustrative of the technical solutions of the present invention. The method for controlling the optimization of water cooling of lining concrete with different strengths according to the present invention is not limited to the contents described in the above embodiments, but is subject to the scope defined by the claims. Any modification or supplement or equivalent replacement made by a person skilled in the art on the basis of this embodiment is within the scope of the invention as claimed in the claims.
Claims (9)
1. The optimal control method for water cooling of lining concrete with different strengths is characterized by comprising the following steps of:
step 1, obtaining water cooling temperature control data of lining concrete;
step 2, calculating water cooling time T according to lining concrete strengthd：
Td2.0H +0.04C +3.0 (formula 1)
In the formula: h is the thickness of the lining concrete; c, designing age strength grade for the lining concrete 90 d;
step 3, calculating water cooling optimal control water temperature T according to lining concrete strengthwy：
Twy17.22-0.17C (formula 2)
Step 4, calculating optimization control according to lining concrete strengthCooling rate [ V ]c】：
【Vc0.14C-2.16 (formula 3)
Step 5, cooling time T according to waterdOptimally controlling water temperature TwyOptimally controlling the temperature drop rate [ V ]cOptimizing lining concrete water cooling measures.
2. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as claimed in claim 1, wherein:
wherein, in the water cooling measure taken in the step 5, the water cooling time is controlled to be not less than Td。
3. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as claimed in claim 1, wherein:
wherein, in the water cooling measure adopted in the step 5, the water cooling time is controlled to be Td～(Td+0.5 d).
4. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as claimed in claim 1, wherein:
wherein, in the water cooling measures adopted in step 5, the water temperature should be controlled to be (T)wy－0.5℃)～(Twy+1 ℃ range.
5. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as claimed in claim 1, wherein:
wherein, in the water cooling measures adopted in the step 5, the temperature reduction rate should be controlled not to exceed Vc】。
6. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as claimed in claim 1, wherein:
wherein, the control processing device is adopted to execute the steps 2 to 4 and calculate the water cooling time TdWater temperature TwyTemperature drop rate [ V ]c】。
7. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as recited in claim 6, wherein:
wherein, the control processing device is also adopted to execute the step 5 according to the cooling time T of the waterdWater temperature TwyTemperature drop rate [ V ]cAnd determining a water cooling measure, and controlling a water cooling system to execute the water cooling measure to carry out water cooling maintenance on the lining concrete.
8. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as recited in claim 7, wherein:
and (3) executing the step (1) by adopting a control processing device, and inputting and storing the water-feeding cooling temperature control data of the lining concrete by a user according to the prompt.
9. The method for optimizing and controlling the water cooling of the lining concrete with different strengths as recited in claim 8, wherein:
wherein, the control processing device is also adopted to display the input information, the calculation result and the determined water cooling measures according to the user command.
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