CN113158298A - Water cooling temperature control method for optimal control of concrete water temperature difference of lining structure - Google Patents

Water cooling temperature control method for optimal control of concrete water temperature difference of lining structure Download PDF

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CN113158298A
CN113158298A CN202110318550.8A CN202110318550A CN113158298A CN 113158298 A CN113158298 A CN 113158298A CN 202110318550 A CN202110318550 A CN 202110318550A CN 113158298 A CN113158298 A CN 113158298A
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temperature
water
concrete
water cooling
lining structure
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CN113158298B (en
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段亚辉
陈浩怀
苗婷
段次祎
吴博
王雷
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Qingyuan Water Conservancy And Hydropower Engineering Supervision Co ltd
Wuchang University of Technology
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Qingyuan Water Conservancy And Hydropower Engineering Supervision Co ltd
Wuchang University of Technology
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Abstract

The invention provides a method for optimally controlling the water cooling and temperature control of concrete water temperature difference of a lining structure, which can objectively and accurately obtain the water temperature difference suitable for concrete of different lining structures, and carries out water cooling on the lining structure based on the water temperature difference, thereby scientifically and reasonably realizing water cooling, temperature control and crack prevention. The method comprises the following steps: step 1, obtaining water cooling temperature control data of lining structure concrete; step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structurewy2.62-3.19H +0.61C +0.12 HC; step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water coolingmax(ii) a Step 4, calculating the water cooling optimal control water temperature T of the concrete of the lining structurewy＝Tmax‑△Twy(ii) a Step 5, optimally controlling the water temperature T according to water coolingwyOptimized lining structureAnd (5) water cooling measures of the concrete.

Description

Water cooling temperature control method for optimal control of concrete water temperature difference of lining structure
Technical Field
The invention belongs to the technical field of concrete temperature control and crack prevention, and particularly relates to a method for optimally controlling water cooling and temperature control of concrete with a lining structure through water temperature difference.
Background
By using the experience of reducing the highest temperature of concrete and successfully controlling the temperature control and crack prevention by controlling the temperature difference inside and outside by means of water cooling of a cooling water pipe embedded in mass concrete, in order to effectively control temperature cracks, a large amount of water cooling measures are taken for lining concrete in a hydraulic tunnel of a huge hydropower station such as a power generation diversion tunnel of a right bank of a three gorges hydropower hub to a stream ferry, a white crane beach, a Wudongde and the like. But the hydraulic tunnel design specification and regulations on the aspects of water cooling temperature and temperature drop rate control of water through lining concrete are not provided in the regulations. The design specification of a concrete gravity dam is often referred to, the temperature difference between the concrete of the dam body and cooling water is not more than 25 ℃, and the cooling speed of the dam body is not more than 1 ℃/d; or the design specification of the concrete arch dam is stipulated, the cooling speed of the dam body is not more than 1 ℃/d when water is introduced for cooling, and the temperature difference between the concrete temperature and the cooling water is not more than 20-25 ℃; and the hydraulic concrete construction specification stipulates that the difference between the concrete temperature and the water temperature should not exceed 25 ℃, and the daily cooling temperature should not exceed 1 ℃.
According to the research on the influence of the simulated concrete pouring process on the first-stage water cooling temperature of the high-concrete arch dam on the concrete around the water pipe: 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 the 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 the concrete is poured, and the temperature of the concrete around the water pipe is kept close to the water temperature without increasing to a high temperature (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 thin-wall lining structure concrete has small thickness, is poured once, is cooled by water when covering the cooling water pipe with the concrete, is equivalent to the condition of newly pouring the concrete on the upper part, has no obvious temperature reduction process around the pipe and has small tensile stress. Therefore, for the water cooling of the concrete with the thin-wall lining structure, the water temperature difference should be determined by obtaining the optimal temperature control anti-cracking effect (called as the water cooling optimization control water temperature of the concrete with the lining structure). Moreover, the thickness of the lining structure is different, the strength of concrete is different, and the optimal control of water temperature difference by water cooling can have larger difference.
However, at present, relevant regulation provisions such as hydraulic tunnels and the like do not scientifically calculate the water temperature difference, and a method for optimally regulating and controlling the water temperature of the lining concrete through water cooling is provided according to the water temperature difference.
Disclosure of Invention
The invention is made to solve the above problems, and aims to provide a method for controlling the temperature of concrete with a lining structure by water cooling in an optimized control mode, which can objectively and accurately obtain the water temperature difference suitable for the concrete with different lining structures, and carry out water cooling on the lining structure based on the water temperature difference, thereby scientifically and reasonably realizing water cooling, temperature control and cracking prevention.
In order to achieve the purpose, the invention adopts the following scheme:
as shown in FIG. 2, the invention provides a method for optimally controlling water cooling and temperature control of concrete water temperature difference of a lining structure, which is characterized by comprising the following steps:
step 1, obtaining water cooling temperature control data of lining structure concrete;
step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structurewy(℃)：
△Twy2.62-3.19H +0.61C +0.12HC (equation 1)
In the formula: h is the thickness (m) of the concrete of the lining structure; c is the strength grade (MPa) of the lining concrete 90d design age, and if the concrete strength of the lining structure is 28d age strength, the concrete strength needs to be converted into 90d design age according to the specification;
step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water coolingmax(℃)：
Tmax＝10.91H+0.051C+0.712T0+0.13Tg+0.51Ta-0.138H×Tg-0.0061T0×Tg+0.0335H×C-0.178
H×Ta-0.0295H(Ta-Tmin) +3.89 (equation 2)
In the formula, T0The concrete pouring temperature (DEG C), TgThe value of the effect of water cooling (DEG C), TaIs the environmental temperature (DEG C) of the concrete pouring period, TminThe lowest winter temperature (DEG C) of the annual change of the air temperature in the tunnel;
step 4, calculating the water cooling optimal control water temperature T of the concrete of the lining structurewy(℃)：
Twy＝Tmax-△Twy(formula 3)
Step 5, optimally controlling the water temperature T according to water coolingwyAnd optimizing the water-through cooling measure of the concrete with the lining structure.
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, 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 greater than (T)wy-1 ℃) and smallIn (T)wy+2℃)。
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: in step 3, Tg＝35℃-Tw，TwThe temperature (DEG C) of cooling water is set up to optimize the requirement or design of the scheme.
Calculating the internal maximum temperature T from equation 2maxIf a planned water cooling measure scheme (or design technical requirement) exists, taking TwThe water cooling water temperature T is introduced for the proposed scheme or the design technical requirement0Setting the pouring temperature for the planned scheme (step 7, further optimizing the water temperature of the water cooling system); if no water cooling measure scheme (or design technical requirement) is drawn up, the actual project T is consideredwGenerally, T is 12-22 deg.CwTaking T at 17 ℃0Estimated as the average temperature in the month +2 ℃. T thus estimatedmaxThe error of the value is generally less than 1.0 ℃, and the optimization of the water cooling water temperature in the step 5 is not influenced basically. If the optimization precision needs to be further improved, the step 5 can be carried out to determine the construction water cooling optimization water temperature and then the step 3 is carried out to calculate the TmaxAnd 4, calculating the optimal control water temperature TwyAnd then, the step 5 is carried out to correct the optimized water cooling measure.
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: executing the steps 2 to 4 by adopting a control processing device, and calculating the water cooling optimal control water temperature difference Delta TwyMaximum temperature TmaxWater temperature Twy。
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: and (5) executing the step 5 by adopting a control processing device, and optimally controlling the water temperature difference delta T according to the water coolingwyMaximum temperature TmaxWater temperature TwyAnd determining a water cooling measure, and controlling a water cooling system to carry out water cooling maintenance on the concrete with the brick structure.
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: and (3) executing the step (1) by adopting a control processing device, and inputting the data for water-through cooling and temperature control of the concrete with the lining structure by a user according to the prompt and storing the data.
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: and the control processing device is also adopted to display the input information, the calculated result and the optimized water cooling measures according to the user instruction.
Preferably, the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the concrete with the lining structure, provided by the invention, can also have the following characteristics: and the control processing device is also adopted to display the running condition of the water cooling system according to the user instruction.
In addition, the calculation of the water cooling optimization control water temperature difference Delta T of the concrete of the lining structure proposed in the step 2wyThe formula 1 is to take giant hydropower station flood discharging tunnel engineering such as Xiluodie, white Crane beach, Wudongde and the like as an example, a three-dimensional finite element method is adopted to carry out temperature and temperature stress simulation calculation on lining concrete with different thicknesses and different strength grades on an urban door opening type section under different water cooling water temperature conditions, the temperature control anti-cracking effect of the lining concrete in the whole process is analyzed in a finishing mode, the principle of maximizing the anti-cracking safety coefficient in the whole process is obtained, and the optimal water temperature difference of water cooling of the lining concrete with different thicknesses and different strength grades is obtained. For example, a 1.0m thickness sidewall C adopting a structure (FIG. 1)9030 strength concrete with different water temperatures T of 8-22 ℃ in the table 1wPerforming 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、K2With the temperature T of the waterwSee fig. 3. The internal maximum temperature T can also be adjustedmaxWith the temperature T of the waterwDifference (i.e. water temperature difference DeltaT)cw) With the temperature T of the waterwSee fig. 4. Due to K1With TwIncrease, K2With TwDecrease, then two curvesThe intersection point of the water temperature T is the water temperature T which can obtain the maximization of the whole process anti-cracking safety coefficientwy. Corresponding to the value, hereinafter referred to as water cooling comprehensive optimization crack resistance safety factor Ky. And KyThe corresponding water cooling temperature is called as the optimal control water temperature TwyThe temperature reduction rate is called as the optimized control temperature reduction rate VyThe water temperature difference is called as the optimal control water temperature difference delta Twy。
According to different thicknesses C90Simulation calculation of 30-lining concrete and making of water temperature difference delta TcwAnd TwThe relationship of (a) is shown in FIG. 4. From K in FIG. 31(Tw) And K2(Tw) Intersection determination TwyA value of TwyThe values are determined in FIG. 4wySummarizing the Delta T of lining concrete with different thicknesses H and different strength gradeswyThe values are shown in Table 2. Then, the data are analyzed and researched to obtain the water cooling optimal control water temperature difference delta TwyEquation 1 is calculated.
TABLE 11.0 m Lining C 9030 concrete water cooling characteristic values at different water temperatures
Figure BDA0002991839700000041
TABLE 2 Water cooling optimization control of water temperature difference DeltaT for lining concrete of different thickness and different strength gradewy
Figure BDA0002991839700000042
Figure BDA0002991839700000051
Step 3, estimating the maximum internal temperature T of the concrete of the lining structure under the condition of water coolingmaxThe formula 2 represents typical generalization of the sections of the three gorges, the brook ferry, the white crane beach, the Wudongde and the like, and the parameters of the lining concrete and the construction temperature control scheme, and totally carries out 175 scheme temperatures in the tables 3 and 4And (5) field simulation calculation. According to tables 3 and 4, the height of the side wall, the length of the parting, the deformation modulus of the surrounding rock, the water passing time, the annual variation of the air temperature and the pouring date do not influence the internal highest temperature TmaxTo TmaxThe thickness H of lining, the strength C of concrete and the pouring temperature T0Water cooling temperature TwAnd the temperature T in the tunnel in the casting periodaThe relationship of (a) is studied and analyzed to obtain formula 2.
TABLE 3 calculation of temperature crack mechanism and factor influence of lining concrete
Figure BDA0002991839700000052
Figure BDA0002991839700000061
Figure BDA0002991839700000071
Note: the distance between the water pipes in the water cooling condition is 1.0m, the length of a single water pipe is 100m, and the flow is 35L/min, which is the same as the following steps.
TABLE 4 temperature control, crack prevention, simulation and calculation supplementary scheme for lining concrete of urban portal section
Figure BDA0002991839700000072
Figure BDA0002991839700000081
Figure BDA0002991839700000091
Figure BDA0002991839700000101
Action and Effect of the invention
The method for optimally controlling the water cooling temperature of the concrete with the lining structure by the water temperature difference has the advantages that:
(1) the method can be suitable for any lining structure (including different civil engineering types, different structural forms, different thicknesses, different strengths and the like) to carry out water cooling of lining concrete and optimal control of water temperature.
(2) The method is scientific. The water cooling water temperature difference calculation formula 1 comprehensively reflects the influence of the thickness and the strength grade of the concrete of the lining structure on the water cooling effect, and is the water temperature difference corresponding to the maximum value of the anti-cracking safety coefficient in the whole process. The calculation formula 2 of the internal highest temperature scientifically reflects the thickness H of the lining, the strength C of the concrete and the pouring temperature T0Water cooling temperature TwAnd the temperature T in the tunnel in the casting periodaThe relationship (2) of (c). Therefore, the water temperature of the water cooling obtained by substituting the calculation results of the formulas 1 and 2 into the formula 3 is a water temperature value capable of obtaining the maximum anti-cracking safety coefficient, and the water cooling is carried out according to the water temperature value, so that the optimal effect of temperature control and anti-cracking can be scientifically obtained.
Drawings
FIG. 1 is a structural section view of a gate-opening type lining concrete of a hydraulic tunnel (dimension unit: m in the figure);
FIG. 2 is a flow chart of a method for controlling the temperature of concrete water through cooling by optimal control of the water temperature difference of the lining structure 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 shows a graph C according to the present invention 9030 concrete water temperature difference delta TcwWater is introduced for cooling water temperature TwA relationship diagram of (1);
FIG. 5 is a sectional view of a lining structure of a flat non-pressure section on a flood discharge tunnel of a white crane beach hydropower station according to the invention (the dimension unit in the figure: cm);
FIG. 6 shows a graph 2 according to the present invention#Unit 2 left side of tunnel portal section of flood discharge tunnelThe time curve graph of the actually measured internal temperature of the side wall is obtained;
fig. 7 is a graph of 145 units of lined concrete internal temperature over time according to the present invention.
Detailed Description
The concrete embodiment of the method for optimally controlling the water cooling temperature by controlling the water temperature difference of the lining structure concrete according to the invention is explained in detail below by taking lining structure concrete at different parts of a flood discharging tunnel project of a white crane beach hydropower station as an example with reference to the attached drawings.
< concrete temperature control data of lining structure of flood discharge tunnel engineering of white crane beach hydropower station >
The white crane beach hydropower station has an installed capacity of 16000MW, and is the 2 nd hydropower station (second to the three gorges) all over the world. The hub project consists of main buildings such as a barrage, a flood discharge and energy dissipation building, a water diversion and power generation system and the like. The flood discharge facility comprises 6 surface holes of a dam, 7 deep holes and 3 flood discharge tunnels on the left bank. 3 flood discharging holes are arranged on the left bank, a non-pressure flood discharging hole type is adopted, and the flood discharging holes are all composed of a water inlet (a gate chamber), a non-pressure slope relieving section, a dragon falling tail section and an outlet drift bucket, 1#、2#The falling tail of the flood discharge tunnel is reversely arc-connected with the flip bucket, 3#The tail end of the reverse arc is connected with a lower flat section with the gradient of 8% and then connected with an outlet flip bucket due to the limitation of topographic conditions.
The tunnel body section of the flood discharge tunnel comprises a pressure discharge section and a landing tail section, which are all of an urban portal-shaped section and are divided into four basic lining types with the thickness of 1.0m, 1.2m, 1.5m and 2.5m according to the characteristics of different lining thicknesses, surrounding rocks and the like. The maximum allowable temperature for the flood tunnel lining concrete design is shown in table 5.
Table 5 unit of maximum temperature allowed during construction of flood tunnel lining concrete: c
Engineering site 5 to 9 months 3. Months 4, 10 and 11 12. 1, 2 months
Upper flat section 1.0m 38 36 34
Upper flat section 1.5m 41 39 37
Upper flat section 2.5m 43 41 39
Dragon falling tail 1.2m 40 38 36
Dragon falling tail 1.5m 42 40 38
Carry out temperature control to the concrete at the overall process of concrete placement and maintenance, avoid the concrete fracture, the design requirement temperature control measure includes:
(1) the mixing proportion of the concrete is optimized, and the crack resistance of the concrete is improved.
(2) Reasonably arranging concrete construction procedures and construction progress and striving to improve the construction management level.
(3) And controlling the highest temperature in the concrete. The effective measures comprise the reduction of the concrete pouring temperature, the reduction of the hydration heat temperature rise of the cementing material, the initial water supply and the like. And (5) water cooling time, wherein the surface temperature of the concrete is required to reach the air temperature of the tunnel, and the water cooling time is generally required to be 10-20 d. Controlling the pouring temperature of the lining concrete, wherein the pouring temperature is 20 ℃ in 4-9 months; the temperature of 10 months to 3 months in the next year is 18 ℃. The concrete transporting tool should have heat insulation and sun shading measures, so that the concrete insolation time is shortened, and the temperature rise in the concrete transporting and pouring process is reduced. Concrete pouring in high-temperature time is avoided as much as possible, and pouring in low-temperature seasons, morning and evening and night with low air temperature is fully utilized.
<Example one>2#Water cooling temperature control is led to in 2 nd unit lining cutting structure concrete temperature difference optimal control of flood discharge tunnel entrance
2#The 2 nd unit of the tunnel portal section of the flood discharge tunnel, the city portal lining, the lining thickness of the side wall is 2.5m, the circumferential construction joints are arranged every 12m along the axial direction of the flood discharge tunnel, the class III surrounding rocks, the bottom plate and the side wall of the lining structure are C 9040 concrete, as shown in FIG. 5 (cross-sectional size after lining was constant, thickness 2.5 m). Pouring concrete by stages 3: side walls, a rear arch and a bottom plate. The calculation of the side wall lining concrete pouring water cooling optimization control water temperature is introduced. The basic data of temperature control are the same as above. And (5) moisturizing and maintaining for 90 days by adopting normal-temperature tap water, and introducing water for cooling to control the internal temperature of the concrete.
As shown in fig. 2, the method for calculating the optimal water temperature for controlling the water cooling of the concrete with the thin-wall lining structure provided by the embodiment includes the following steps:
step 1, analyzing relevant data of water cooling and temperature control of concrete with a lining structure, comprising the following steps of: collecting data related to temperature control and crack prevention of the lining concrete, analyzing the importance of the temperature control and crack prevention of the lining concrete, and analyzing the technical requirements of temperature control design of the lining concrete.
The flood discharge tunnel of the hydropower station of the white beach is a level 1 building, the flow velocity of water flow is close to 50m/s, and the temperature control and crack prevention of concrete are very important. Depending on design requirements, effective measures including water cooling for temperature control are required. The concrete temperature control, the allowable maximum temperature, the temperature control anti-cracking measure and other technical requirements are as above.
According to the engineering data, the 2 nd unit lining concrete at the inlet section of the flood discharge tunnel needs to control the pouring temperature and take water cooling measures. Pouring at 8 months and 5 days in 2017 at the pouring temperature of less than or equal to 20 ℃, wherein the allowable maximum temperature of the lining concrete with the thickness of 2.5m is 43 ℃ according to the design requirements of the table 2. And (3) carrying out simulation calculation on recommended high-temperature season pouring temperature control measures by using a finite element method: pouring at 18 ℃, cooling by water at 12 ℃ and preserving heat for 16 ℃ in winter; and calculating the highest internal temperature of 43 ℃, the crack resistance safety coefficient of 1.56 and the cooling time of 10 days by introducing water. The temperature in the tunnel is 26 ℃ at the maximum in summer and 14 ℃ at the minimum in winter, and the temperature in the tunnel is 16 ℃ at the minimum in winter by heat preservation.
Step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structurewy：
Substituting H2.5 m and C40 MPa into equation 1 to calculate Δ Twy＝31℃。
Step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water coolingmax：
According to the above description, since the finite element method simulation calculation in the engineering data recommends the temperature control measure scheme, here the optimization control, the casting temperature and the water cooling water temperature take the recommended values, T 018 ℃ and Tw 12 ℃. H2.5 m, C40 MPa, T0＝18℃，TwCalculating T at 12 ℃g＝35-12＝23℃，Ta＝26℃，TminSubstituting 16 deg.C into equation 2 to calculate Tmax43.29 ℃. It can be seen that equation 2 calculates TmaxThe value is very close to the simulation calculated value of the finite element method of 43 ℃, and the precision is high.
Step 4, calculating the water cooling optimal control water temperature T of the concrete of the lining structurewy：
Will Tmax＝43.29℃，△TwySubstituting 31 deg.C into equation 3, and calculating Twy12.29 ℃. Get Twy12 ℃. The method is completely consistent with the simulation calculation recommendation value of the finite element method.
Step 5, optimizing a water cooling temperature control scheme of the lining concrete, comprising the following steps: and calculating and optimizing water temperature, introducing water for cooling based on formulas 1-3, and controlling the temperature in the concrete curing period.
Based on the calculation results of the formulas 1-3, the water cooling water temperature T is recommended to be introducedwy12 ℃. In order to obtain the optimal temperature control anti-cracking effect, the hydropower 5 is locally provided with a special cooling water refrigeration system at the opening of the flood discharge tunnel, so that the water temperature can be optimally controlled in real time. And (3) determining a construction temperature control scheme in the structural section, and introducing 12 ℃ refrigeration water for cooling.
And analyzing the temperature control effect of the lining concrete. 2#And (3) pouring the No. 2 unit at the tunnel portal section of the flood discharge tunnel in 2017 in 8-month and 5-day period, and burying 1 thermometer in the lower part 2m and the middle part of the side wall on the left side respectively. And (3) water cooling time period: 8 months 5 days-8 months 15 days. The water is introduced for cooling, and the temperature is 12 ℃. The casting temperature is measured to be 15.4 ℃, the maximum temperature is measured to be 41.0 ℃, 38.1 ℃ after 77 hours and 50 minutes, the maximum daily cooling rate is 1.41 ℃/d, and the temperature duration curve is shown in figure 6. And (4) checking in situ without any temperature crack.
The results show that the concrete Tmax41.0 ℃, 38.1 ℃ and 43 ℃ lower than the maximum temperature allowed by design; the maximum value of the temperature drop speed is 1.41 ℃/d and is far less than the allowable value of 2.0 ℃/d. The field inspection shows that no temperature crack exists, and the temperature control anti-cracking effect has good effect.
By combining the analysis, the water cooling temperature calculated by adopting the method (formula 1-3) is completely consistent with the simulation calculation recommended value of the finite element method; the difference between the estimated internal highest temperature of the formula 2 and the simulation calculated value of the finite element method is only 0.29 ℃ (0.7%), and the precision is high; and water is introduced for cooling according to the water temperature to obtain the optimal temperature control anti-cracking effect, the highest temperature is less than the simulation calculated value and the estimated value of the finite element method by 2 ℃, and the anti-cracking safety coefficient is improved. Formulas 1-3 scientifically reflect the relation between the thickness and strength of the lining structure and the water temperature of water cooling, and achieve the aim of controlling the highest temperature and the maximum inner surface temperature difference inside concrete through water cooling, so that the temperature control benefit and the economic benefit are maximized.
<Example two>1#Water cooling temperature control is led to in 145 th unit lining structure concrete temperature difference optimal control of flood discharge tunnel upper flat section
1#145 th unit of the upper flat section of the flood discharge tunnel, an urban portal-shaped lining, the thickness of the side wall lining is 1.0m, and the rings are arranged every 12m along the axial direction of the flood discharge tunnelConstruction parting, class III surrounding rock, lining structure bottom plate and side wall are C 9040 low heat cement concrete, as shown in fig. 5. Pouring concrete by stages 3: side walls, a rear arch and a bottom plate. The optimal control of the water cooling temperature by the water temperature difference of the side wall lining concrete is introduced. The basic data of temperature control are the same as above. And (5) moisturizing and maintaining for 90 days by adopting normal-temperature tap water, and introducing water for cooling to control the internal temperature of the concrete.
As shown in fig. 2, the method for optimally controlling the water temperature difference of concrete with a lining structure to control the water cooling temperature includes the following steps:
step 1, analyzing relevant data of water cooling and temperature control of concrete with a lining structure:
collecting data related to temperature control and crack prevention of the lining concrete, analyzing the importance of the temperature control and crack prevention of the lining concrete, and analyzing the technical requirements of temperature control design of the lining concrete.
The flood discharge tunnel of the hydropower station of the white beach is a level 1 building, the flow velocity of water flow is close to 50m/s, and the temperature control and crack prevention of concrete are very important. Depending on design requirements, effective measures including water cooling for temperature control are required. The concrete temperature control, the allowable maximum temperature, the temperature control anti-cracking measure and other technical requirements are as above.
Based on the above engineering data, 1#Concrete is lined in the 145 th unit of the upper flat section of the flood discharge tunnel, and pouring temperature needs to be controlled, and water cooling measures need to be taken. Pouring is carried out at 25 days in 5 months, the pouring temperature is less than or equal to 20 ℃, and the allowable maximum temperature of the lining concrete with the thickness of 1.0m in the upper flat section is 38 ℃ according to the design requirements of the table 2. And (3) carrying out simulation calculation on recommended high-temperature season pouring temperature control measures by using a finite element method: pouring at 18 ℃, cooling by water at 12 ℃ and preserving heat for 16 ℃ in winter; and calculating the highest internal temperature of 34.17 ℃, the anti-cracking safety coefficient of 1.65 and the cooling time of 10 days by introducing water. The temperature in the tunnel is 26 ℃ at the maximum in summer and 14 ℃ at the minimum in winter, and the temperature in the tunnel is 16 ℃ at the minimum in winter by heat preservation.
Step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structurewyIt is calculated by equation 1.
Substituting H1.0 m and C40 MPa into equation 1 to calculate Δ Twy＝28.63℃。
Step 3. estimateCalculating the highest internal temperature T of the lining structure concrete under the condition of water coolingmaxIt is calculated by equation 2.
According to the above description, since the finite element method simulation calculation in the engineering data recommends the temperature control measure scheme, here the optimization control, the casting temperature and the water cooling water temperature take the recommended values, T0＝18℃，Tw12 ℃. H is 1.0m, C is 40MPa, T0＝18℃，Tw＝12℃，Tg＝35-12＝23℃，Ta＝26℃，TminSubstituting 16 deg.C into equation 2 to calculate Tmax35.05 ℃ (calculated for low heat cement). It can be seen that equation 2 calculates TmaxThe value is very close to the finite element method simulation calculated value of 34.17 ℃, and the precision is high.
Step 4, calculating the water cooling optimal control water temperature T of the concrete of the lining structurewy：
Will Tmax＝35.05℃，△TwySubstituting 28.63 ℃ into equation 3 to calculate Twy6.42 ℃. Get TwyAt 7 ℃. And the water cooling effect is improved when the temperature is lower than the simulation calculation recommended value of the finite element method by 12 ℃.
Step 5, optimizing a water cooling temperature control scheme of the lining concrete, comprising the following steps: and calculating and optimizing water temperature, introducing water for cooling based on formulas 1-3, and controlling the temperature in the concrete curing period.
Based on the calculation results of formulas 1-3, the water cooling water temperature T is recommended to be introducedwyAt 7 ℃. In order to obtain the optimal temperature control anti-cracking effect, the hydropower 5 is locally provided with a special cooling water refrigeration system at the opening of the flood discharge tunnel, so that the water temperature can be optimally controlled in real time. And (3) determining a construction temperature control scheme in the structural section, and introducing 7 ℃ refrigeration water for cooling.
145 units of lining concrete temperature control effect:
145 units concrete pouring period: 5/25/2019 15: 00-5/27/2019 (01): 30 hours. Construction units in construction period carry out temperature control related detection: the average casting temperature is 18.41 ℃ (the average value of the measured temperature when 4 thermometers are covered by concrete is taken); the water was passed through to cool the mixture at an average water temperature of 7 ℃.
Concrete cover thermometer to start concrete internal temperatureAnd observing, pouring concrete, covering a thermometer, and starting water cooling. Maximum temperature T of left side wallmax34.12 ℃, appearance time 1.98d, Δ Tmax4.37 ℃, appearance time 3.22 d; right side wall, highest temperature Tmax32.56 ℃, appearance time 2.83d, Δ Tmax4.81 ℃ and appearance time 3.98 d. The temperature history is shown in FIG. 7. And (4) checking in situ without any temperature crack.
The results show that the concrete Tmax34.12 ℃, 32.56 ℃ and less than the maximum allowable design temperature of 38 ℃; the maximum inner surface temperature difference is 4.37-4.81 ℃, and the temperature is relatively small. The anti-cracking safety coefficient is more than 1.7, and temperature cracks can not occur. The temperature and temperature control anti-cracking effect is consistent with the field actual measurement result. The actual internal highest temperature is lower than the simulation calculated value of the finite element method because the water temperature is optimized and the anti-cracking effect is achieved.
The water cooling water temperature calculated by the method (formula 1-3) is better than the recommended value calculated by finite element method simulation; the error between the estimated internal highest temperature by the formula 2 and the simulation calculation value of the finite element method is small, and the precision is high; and water is introduced for cooling according to the water temperature to obtain the optimal temperature control anti-cracking effect, the highest temperature is smaller than the simulation calculated value of the finite element method and the estimated value of the formula, and the anti-cracking safety coefficient is improved. Formulas 1-3 scientifically reflect the relation between the thickness and strength of the lining structure and the water temperature of water cooling, and achieve the aim of controlling the highest temperature and the maximum inner surface temperature difference inside concrete through water cooling, so that the temperature control benefit and the economic benefit are maximized.
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 thicknesses, different strengths, different temperature control measure schemes and the like), and the water temperature difference of the concrete of the lining structure is optimized to control the water cooling temperature, namely the water cooling temperature is optimized by the actual construction temperature control measure scheme.
The method is scientific. The water cooling of the concrete with the lining structure is used for optimizing and controlling the water temperature, and the influence of main parameters such as the thickness, the strength, the environmental condition, the temperature control measure and the like of the concrete structure with the lining structure is comprehensively reflected.
The temperature difference control value of the concrete of the thin-wall lining structure and the water cooling water is calculated according to the formula 1, optimization is reasonable, the water temperature value with the maximum crack resistance safety coefficient is obtained, the target of controlling the highest temperature inside the concrete and the maximum inner surface temperature difference through water cooling is scientifically achieved, and the temperature control benefit and the economic benefit are maximized.
The above embodiments are merely illustrative of the technical solutions of the present invention. The method for controlling the temperature of the concrete water in the lining structure by optimizing and controlling the temperature difference of the water cooling 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 (10)

1. The method for controlling the temperature of the concrete with the lining structure by optimally controlling the water temperature difference through water cooling is characterized by comprising the following steps of:
step 1, obtaining water cooling temperature control data of lining structure concrete;
step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structurewy：
△Twy2.62-3.19H +0.61C +0.12HC (formula 1) wherein: h is the thickness of the lining structure concrete, and C is the age strength grade of the lining concrete 90 d;
step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water coolingmax：
Tmax＝10.91H+0.051C+0.712T0+0.13Tg+0.51Ta-0.138H×Tg-0.0061T0×Tg+0.0335H×C-0.178H×Ta-0.0295H(Ta-Tmin) +3.89 (equation 2) where T is0For concrete casting temperature, TgFor water-cooling effect value, TaIs the environmental temperature, T, of the concrete casting periodminThe lowest temperature in winter is the annual change of the air temperature in the tunnel;
step 4, calculating the water cooling optimal control water temperature T of the concrete of the lining structurewy：
Twy＝Tmax-△Twy(formula 3)
Step 5, optimally controlling the water temperature T according to water coolingwyAnd optimizing the water-through cooling measure of the concrete with the lining structure.
2. The method for controlling the temperature of the lining structure concrete by optimizing the water temperature difference and cooling according to claim 1, which is characterized in that:
wherein, in the water cooling measures adopted in the step 5, the water temperature should be controlled to be more than (T)wy-1 ℃) and less than (Twy+2℃)。
3. The method for controlling the temperature of the lining structure concrete by optimizing the water temperature difference and cooling according to claim 1, which is characterized in that:
wherein, in step 3, Tg＝35℃-Tw，TwThe temperature (DEG C) of cooling water is set up to optimize the requirement or design of the scheme.
4. The lining structure concrete water temperature difference optimal control water cooling temperature control method according to claim 3, characterized in that:
wherein if no scheme is drawn, taking TwTaking T at 17 ℃0Estimated as the average temperature in the month +2 ℃.
5. The method for controlling the temperature of the lining structure concrete through water cooling according to claim 4, which is characterized in that:
under the condition that no scheme is drawn up, after the optimal water cooling measures of the lining structure concrete are obtained in the step 3-5, the optimal water cooling measures are taken as the drawn up scheme, and the step 3 and the step 4 are further returned to calculate TmaxAnd TwyAnd then, the step 5 is carried out to correct the optimized water cooling measure.
6. The method for controlling the temperature of the lining structure concrete by optimizing the water temperature difference and cooling according to claim 1, which is characterized in that:
wherein, the control processing device is adopted to execute the steps 2 to 4, calculate the water cooling optimal control water temperature difference Delta TwyMaximum temperature TmaxWater temperature Twy。
7. The method for controlling the temperature of the lining structure concrete through water cooling according to claim 6, which is characterized in that:
wherein, a control processing device is also adopted to execute the step 5, and the water temperature difference Delta T is optimally controlled according to the water coolingwyMaximum temperature TmaxWater temperature TwyAnd determining a water cooling measure, and controlling a water cooling system to carry out water cooling maintenance on the concrete with the brick structure.
8. The method for controlling the temperature of the lining structure concrete through water cooling according to claim 7, which is characterized in that:
and (3) executing the step (1) by adopting a control processing device, and inputting the data for water-feeding, cooling and temperature control of the concrete with the lining structure by a user according to the prompt and storing the data.
9. The lining structure concrete water temperature difference optimal control water cooling temperature control method according to claim 8, characterized in that:
wherein, the control processing device is also adopted to display the input information, the calculation result and the optimized water cooling measure according to the user instruction.
10. The lining structure concrete water temperature difference optimal control water cooling temperature control method according to claim 9, characterized in that:
wherein, the control processing device is also adopted to display the running condition of the water cooling system according to the instruction of a user.
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