CN113158298B - 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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CN113158298B
CN113158298B CN202110318550.8A CN202110318550A CN113158298B CN 113158298 B CN113158298 B CN 113158298B CN 202110318550 A CN202110318550 A CN 202110318550A CN 113158298 B CN113158298 B CN 113158298B
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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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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 optimization control water temperature difference delta T of concrete of lining structure wy =2.62-3.19H +0.61C +0.12HC; step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water cooling max (ii) a Step 4, calculating the water cooling optimization control water temperature T of the concrete of the lining structure wy ＝T max ‑△T wy (ii) a Step 5, optimally controlling the water temperature T according to water cooling wy And optimizing the water-through cooling measure of the concrete with the lining structure.

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 supply while being poured, and the temperature of the concrete around the water pipe is kept close to the water temperature without being raised to a high temperature (the initial storage 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 mass concrete such as a multi-layer pouring dam and the like is controlled by no temperature crack generated around the lower-layer old concrete pipe, and the water temperature difference and the temperature drop speed are allowed to be 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 the concrete is different, and the temperature difference of the water can be controlled optimally by water cooling.
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 structure wy (℃)：
△T wy =2.62-3.19H +0.61C +0.12HC (equation 1)
In the formula: h is the thickness (m) of the concrete of the lining structure; c, designing age strength grade (MPa) for lining concrete 90d, and if the concrete strength of the lining structure is 28d age strength, converting the concrete strength 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 cooling max (℃)：
T max ＝10.91H+0.051C+0.712T 0 +0.13T g +0.51T a -0.138H×T g -0.0061T 0 ×T g +0.0335H×C-0.178
H×T a -0.0295H(T a -T min ) +3.89 (equation 2)
In the formula, T 0 The concrete pouring temperature (DEG C), T g The value of the cooling effect (DEG C) is T a The environmental temperature (DEG C) and T in the concrete pouring period min The lowest winter temperature (DEG C) of the annual change of the air temperature in the tunnel;
step 4, calculating the water cooling optimization control water temperature T of the concrete of the lining structure wy (℃)：
T wy ＝T max -△T wy (formula 3)
Step 5, optimally controlling the water temperature T according to water cooling wy And 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 less than (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, T g ＝35℃-T w ，T w The 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 2 max If a planned water cooling measure scheme (or design technical requirement) exists, taking T w The water cooling water temperature T is introduced for the proposed scheme or the design technical requirement 0 Setting 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 considered w Generally between 12 and 22 ℃, T can be taken w =17 ℃ C., T is taken 0 Estimated as the average temperature in the month +2 ℃. T thus estimated max The 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 T max And 4, calculating the optimal control water temperature T wy And then, the step 5 is carried out to correct the optimized water cooling measure.
Preferably, the method for optimally controlling the water temperature difference of the concrete with the lining structure to control the water cooling temperature can also have the following characteristics: executing the steps 2 to 4 by adopting a control processing device, and calculating the temperature difference delta T of the water cooling optimization control water wy Maximum temperature T max Water temperature T wy 。
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 cooling wy Maximum temperature T max Water temperature T wy And 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 measure 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 first and second substrates are,calculating the water cooling optimization control water temperature difference Delta T of the concrete with the lining structure proposed in the step 2 wy The formula 1 is that taking giant hydropower station flood discharging tunnel projects such as Xiluogu, white beach, wudongde and the like as examples, a three-dimensional finite element method is adopted to carry out temperature and temperature stress simulation calculation of lining concrete with different thicknesses and different strength grades on an urban gate-opening type section under different water cooling water temperature conditions, the temperature control and crack prevention effects of the lining concrete in the whole process are analyzed in an arranging way, the whole process crack prevention safety coefficient maximization is obtained, and the optimal water temperature difference 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) 90 30 strength concrete with different water temperatures T of 8-22 ℃ in the table 1 w Performing 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 winter 1 、K 2 Then make K 1 、K 2 With the water temperature T w See fig. 3. The internal maximum temperature T can also be adjusted max With the water temperature T w Difference (i.e. water temperature difference Δ T) cw ) With the temperature T of the water w See fig. 4. Due to K 1 With T w Increase, K 2 With T w The 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 process wy . Corresponding to the value, hereinafter referred to as water cooling comprehensive optimization crack resistance safety factor K y . And K y The corresponding water cooling temperature is called as the optimal control water temperature T wy The temperature reduction rate is called as the optimized control temperature reduction rate V y The water temperature difference is called as the optimal control water temperature difference delta T wy 。
According to different thicknesses C 90 Simulation calculation of 30-lining concrete and making of water temperature difference delta T cw And T w The relationship of (a) is shown in FIG. 4. From K in FIG. 3 1 (T w ) And K 2 (T w ) Intersection determination T wy A value of T wy Values are determined at FIG. 4 wy Summarizing the Delta T of lining concrete with different thicknesses H and different strength grades wy The values are shown in Table 2. Then the data are analyzed and researched to obtain the water cooling optimal control waterTemperature difference delta T wy Equation 1 is calculated.
TABLE 1.0m Lining C 90 30 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 grade wy
Figure BDA0002991839700000042
Figure BDA0002991839700000051
Step 3, estimating the maximum internal temperature T of the concrete of the lining structure under the condition of water cooling max The 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 carries out simulation calculation of 175 temperature fields in the schemes in the tables 3 and 4. According to the table 3 and the table 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 amplitude of the air temperature and the pouring date do not influence the internal highest temperature T max To T, for max The thickness H of lining, the strength C of concrete and the pouring temperature T 0 Water cooling temperature T w And the temperature T in the tunnel in the casting period a The relationship of (a) is studied and analyzed to obtain formula 2.
TABLE 3 calculation conditions 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 effects 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 concrete and the pouring temperature T 0 Water cooling temperature T w And the temperature T in the tunnel in the casting period a The relationship (c) in (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 90 30 concrete curing period K with different thickness 1 And winter K 2 Water cooling water temperature T w A relationship diagram of (1);
FIG. 4 shows a graph C according to the present invention 90 30 concrete water temperature difference delta T cw Water is introduced for cooling water temperature T w A relationship diagram of (a);
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 2 according to the present invention # The measured internal temperature duration curve diagram of the left side wall of the unit 2 at the tunnel opening section of the flood discharge tunnel;
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 strips of a left bankA flood discharge tunnel. 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 5-9 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 (3) the water cooling time is required to reach the surface temperature of the concrete to the air temperature of the tunnel, and generally 10-20 days is required. Controlling the pouring temperature of the lining concrete to be 20 ℃ within 4-9 months; the temperature of 10 months to the next year and 3 months is 18 ℃. The concrete transporting tool should have heat insulation and sun shading measures, so that the exposure time of concrete 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 # Unit 2 at tunnel portal section of flood discharge tunnel and city portal liningThe lining thickness of the side wall is 2.5m, annular construction parting joints are arranged every 12m along the axial direction of the flood discharge tunnel, the class III surrounding rocks, and the bottom plate and the side wall of the lining structure are C 90 40 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 unit 2 at the inlet section of the flood discharge tunnel is lined with concrete, the pouring temperature needs to be controlled, and water cooling measures need to be taken. 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 structure wy ：
Substituting H =2.5m, c =40mpa into formula 1 to calculate Δ T wy ＝31℃。
Step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water cooling max ：
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 value, T 0 =18 ℃, tw =12 ℃. Mixing H =2.5m, C =40MPa 0 ＝18℃，T w =12 ℃, calculating T g ＝35-12＝23℃，T a ＝26℃，T min =16 ℃, and substituting into formula 2 to calculate T max =43.29 ℃. It can be seen that equation 2 calculates T max The 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 structure wy ：
Will T max ＝43.29℃，△T wy =31 ℃ and is substituted into equation 3 to calculate T wy =12.29 ℃. Get T wy =12 ℃. 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 the optimized water temperature based on the formulas 1-3, and carrying out water cooling to control the temperature in the concrete curing period.
Based on the calculation results of the formulas 1 to 3, the water cooling water temperature T is recommended to be introduced wy =12 ℃. In order to obtain the optimal temperature control anti-cracking effect, the hydropower 5 local is provided with a special cooling water refrigerating system at the opening of the flood discharge tunnel, and water can be supplied to Wen Shishi for optimal control. And (3) determining a construction temperature control scheme in the structural section, and introducing 12 ℃ refrigerating 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, 8 and 5 months, and burying 1 thermometer in each of the lower part 2m and the middle part of the side wall on the left side. And (3) water cooling period: 8 months 5 days-8 months 15 days. The water is introduced for cooling, and the temperature is 12 ℃. The casting temperature was found to be 15.4 ℃ for 77 hours and 50 minutes, the maximum temperature was 41.0 ℃, 38.1 ℃ and the maximum daily cooling rate was 1.41 ℃/d, and the temperature duration curve is shown in fig. 6. And (4) checking in situ without any temperature crack.
The results show thatConcrete T max 41.0 ℃, 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. On-site inspection, no temperature crack exists, and good effect is achieved in temperature control and crack prevention.
By combining the analysis, the water cooling temperature calculated by the method (formulas 1 to 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 to 3 scientifically reflect the relation between the thickness and the strength of the lining structure and the temperature of water cooling, realize the target of controlling the highest temperature and the maximum inner surface temperature difference in the concrete by water cooling, and maximize the temperature control benefit and the economic benefit.
<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 lining thickness of a side wall is 1.0m, annular construction parting joints are arranged every 12m along the axial direction of the flood discharge tunnel, class III surrounding rocks, and a bottom plate and a side wall of a lining structure are C 90 40 low heat cement concrete, as shown in fig. 5. Pouring concrete by 3 stages: 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 the 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 a recommended high-temperature season pouring temperature control measure 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 water cooling time of 10 days. 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 through heat preservation.
Step 2, calculating water cooling optimal control water temperature difference delta T of concrete of lining structure wy It is calculated by equation 1.
Substituting H =1.0m, C =40MPa into formula 1 to calculate Delta T wy ＝28.63℃。
Step 3, estimating the highest internal temperature T of the concrete of the lining structure under the condition of water cooling max It 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, T 0 ＝18℃，T w =12 ℃. Mixing H =1.0m, C =40MPa 0 ＝18℃，T w ＝12℃，T g ＝35-12＝23℃，T a ＝26℃，T min =16 ℃, and substituting into formula 2 to calculate T max =35.05 ℃ (calculated for low heat cement). It can be seen that equation 2 calculates T max The 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 structure wy ：
Will T max ＝35.05℃，△T wy =28.63 ℃ and is substituted into equation 3 to calculate T wy =6.42 ℃. Get T wy =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 the optimized water temperature based on formulas 1-3, and cooling by introducing water to control 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 introduced wy =7 ℃. In order to obtain the optimal temperature control anti-cracking effect, the hydropower 5 local is provided with a special cooling water refrigerating system at the opening of the flood discharge tunnel, and water can be supplied to Wen Shishi for optimal control. 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: 5/25/2019-00/5/27/2019 (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 ℃.
The concrete cover thermometer starts to observe the internal temperature of the concrete, and the concrete pouring cover thermometer starts to be cooled by water. Maximum temperature T of left side wall max =34.12 ℃, appearance time 1.98d, Δ T max =4.37 ℃, appearance time 3.22d; right side wall, highest temperature T max =32.56 ℃, epoch 2.83d, Δ Τ max =4.81 ℃, appearance time 3.98d. The temperature history is shown in FIG. 7. And (4) checking in situ without any temperature crack.
The results show that the concrete T max 34.12 ℃, 32.56 ℃ and 38 ℃ below the maximum allowable temperature; the maximum inner surface temperature difference is 4.37-4.81 ℃, and 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 method (formulas 1 to 3) is adopted to calculate the water cooling water temperature which is better than the simulation calculation recommended value of the finite element method; 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 to 3 scientifically reflect the relation between the thickness and the strength of the lining structure and the temperature of water cooling, realize the target of controlling the highest temperature and the maximum inner surface temperature difference in concrete by water cooling, and maximize the temperature control benefit and the economic benefit.
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 cooling temperature control is controlled by optimizing the concrete water temperature difference of the lining structure, namely the water cooling water temperature optimization of the actual construction temperature control measure scheme.
The method of the invention has strong scientificity. The water cooling of the concrete with the lining structure optimizes and controls the water temperature, and comprehensively reflects 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.
The temperature difference control value of the concrete water-cooling water of the thin-wall lining structure is calculated according to the formula 1, optimization is reasonable, the water temperature value with the maximum anti-cracking 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 temperature control benefits and economic benefits 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, supplement or equivalent replacement 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 structure wy ：
△T wy =2.62-3.19H +0.61C +0.12HC (equation 1)
In the formula: h is the thickness of the concrete of the lining structure, 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 cooling max ：
T max =10.91H+0.051C+0.712T 0 +0.13T g +0.51T a -0.138H×T g -0.0061T 0 ×T g +0.0335H×C-0.178H×T a -0.0295H(T a -T min ) +3.89 (equation 2)
In the formula, T 0 Is the concrete casting temperature, T g For water-cooling effect value, T a Is the environmental temperature, T, of the concrete casting period min The 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 structure wy ：
T wy =T max -△T wy (formula 3)
Step 5, optimally controlling the water temperature T according to water cooling wy And optimizing the water-feeding cooling measure of the concrete with the lining structure.
2. The method for controlling the temperature of the lining structure concrete through water cooling and optimizing the water temperature difference according to claim 1, wherein the method comprises the following steps:
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 (T) wy +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, T g =35℃-T w ，T w The temperature of the cooling water is set up according to the scheme requirement or design before optimization.
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 T w =17 ℃, take T 0 Estimated as the average temperature in the current 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 step 3~5 is executed to obtain the optimized water cooling measure of the concrete with the lining structure, the optimized water cooling measure is used as the drawn up scheme, and the step 3 and the step 4 are further returned to calculate T max And T wy And 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 through water cooling and optimizing the water temperature difference according to claim 1, wherein the method comprises the following steps:
wherein, the control processing device is adopted to execute the steps 2 to 4, calculate the water cooling optimal control water temperature difference Delta T wy Maximum temperature T max Water temperature T wy 。
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 adopted to execute the step 5, and the temperature difference Delta T of the water is optimally controlled according to the water cooling wy Maximum temperature T max Water temperature T wy And determining a water-through cooling measure, and controlling a water-through cooling system to carry out water-through cooling maintenance on the concrete of the masonry structure.
8. The method for optimally controlling the water cooling and temperature control of the concrete with the lining structure according to the 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:
and the control processing device is also adopted to display the input information, the calculation result and the optimized water-passing 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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