CN110409387B

CN110409387B - Water-through cooling water temperature control method for concrete with lining structure

Info

Publication number: CN110409387B
Application number: CN201910541481.XA
Authority: CN
Inventors: 段亚辉; 樊启祥; 段次祎; 方朝阳; 付继林; 苏立
Original assignee: Wuhan University WHU; China Three Gorges Projects Development Co Ltd CTG; Wuchang University of Technology
Current assignee: Wuhan University WHU; China Three Gorges Projects Development Co Ltd CTG; Wuchang University of Technology
Priority date: 2019-06-21
Filing date: 2019-06-21
Publication date: 2020-12-18
Anticipated expiration: 2039-06-21
Also published as: CN110409387A

Abstract

The invention provides a water cooling and water temperature control method for concrete of a lining structure, which comprises the following steps: step 1, collecting data for temperature control of lining concrete; step 2, calculating water-feeding cooling control water temperature based on the collected lining concrete temperature control data, comprising the following steps: step 2-1, calculating the allowable temperature difference (delta T) between the lining concrete and the cooling water according to the formula 1_cw2H + 0.6C; step 2-2, calculating the lowest value T of the water cooling water temperature_w,min＝T_max‑【△T_cwH ]; step 2-3, determining the water cooling control water temperature T_w: according to the water temperature condition which can be passed through in the construction site, the lowest value T of the water temperature of the water cooling system is calculated in a combined manner_w,minIs required to satisfy T_w≥T_w,minOn the premise of determining the water temperature T for water cooling control_w(ii) a Step 3, controlling the water temperature T according to the cooling of water_wThe water cooling is carried out on the concrete with the lining structure, the temperature control and crack prevention are realized, and the internal cracks caused by the too fast temperature drop are avoided.

Description

Water-through cooling water temperature control method for concrete with lining structure

Technical Field

The invention belongs to the technical field of temperature control and crack prevention of concrete with a lining structure, and particularly relates to a water cooling and water temperature control method for concrete with a lining structure.

Background

Lining is a structure widely adopted in civil engineering. The lining concrete can be heated up due to the hydration heat of cementing materials such as cement and the like to generate very high internal temperature, for example, the highest temperature inside the lining concrete of a water delivery hole in a permanent ship lock of the three gorges hydro-junction reaches nearly 60 ℃, and the highest temperature inside the lining concrete of a hydropower station water delivery hole at the bottom of small waves reaches more than 70 ℃. The lining structure is small in thickness, high in strength mostly (such as the strength of a flood discharging tunnel of a large hydropower station reaches C50 and C60), high in internal temperature, large in temperature drop amplitude, high in temperature rise and temperature drop speed, and capable of generating temperature cracks easily in the construction period and being mostly penetrating harmful cracks due to the fact that the thin-wall lining is subjected to extremely strong constraints such as surrounding rocks and a supporting structure. As shown in fig. 1, the treatment of cracks seriously affects the progress period and the construction cost of the project, and the failure to repair perfect penetrating cracks (generally difficult to reach the original concrete structure performance) seriously affects the durability and the service life of the lining structure, even causes leakage and threatens the project safety. The leakage of water (tunnel of Dong-deep water supply wild goose field) in the spraying state also directly endangers the health and comfort of people.

The concrete is embedded with the cooling water pipe for water cooling, the highest temperature inside the structural concrete and the temperature difference between the inside and the outside can be effectively reduced, the concrete is an extremely effective temperature control anti-cracking construction measure, and the concrete is widely applied to the construction of various civil and architectural mass concrete engineering. The water cooling measures are adopted in the temperature control and crack prevention of the underground water conveying tunnel of the three gorges permanent ship lock, the temperature control and crack prevention of the underground water conveying tunnel lining of the three gorges permanent ship lock are researched as early as 1999, and the water cooling measures are adopted in the temperature control construction of the middle partition pier water conveying tunnel lining concrete, so that a certain effect is achieved. Later, the construction method is comprehensively adopted in the pressure-section lining concrete temperature control anti-cracking construction of the power generation cave of the three gorges right bank underground power station. In particular to the concrete temperature control anti-cracking construction of underground engineering of hydropower stations such as Xiluodi, white Crane beach, Udongde and the like.

The existing relevant design specifications generally lack clear and specific regulations on temperature control and water cooling of underground cavern engineering lining concrete, and the water cooling of the underground cavern lining concrete in the hydraulic and hydroelectric junction engineering is a method for referring to large-volume concrete water cooling of a dam.

The water cooling is generally adopted in the dam concrete temperature control by 3 stages: in the initial stage, the aim is to control the highest temperature and reduce the highest temperature as much as possible, namely, low-temperature water and high flow are adopted as much as possible; in the middle stage, the purpose is to control the temperature difference between the inside and the outside, and the water temperature is proper; and in the later stage, the aim is to control the temperature drop amplitude of the dam body to a stable temperature after the joint is grouted. However, in any period, the temperature difference and the temperature drop speed between the dam concrete and the cooling water and the water supply time in each period need to be controlled. The temperature difference between the dam concrete and the cooling water is basically consistent in each standard control value and is 20-25 ℃. The temperature drop speed has great difference in each standard control value, and the dam work standard is 1.0 ℃/day; the hydraulic concrete construction specification stipulates that the initial stage is 1.0 ℃/day, and the middle stage is 0.5 ℃/day. The water passing time is not specified in dam work specifications; the hydraulic concrete construction specification stipulates that 10-20 days can be taken for initial cooling, and about 1-2 months is taken for intermediate water cooling. In addition, the hydraulic concrete construction specification also stipulates that the flow velocity of water in the water passing pipe at the initial stage is preferably 0.6-0.7 m/s, and the water flow direction should be changed for 1 time every 24 h.

The temperature difference between the concrete and the cooling water is controlled, so that the highest internal temperature can be effectively reduced, and concrete cracks or concrete cracks around the pipe due to too fast temperature reduction can be avoided. However, the strength of the lining concrete is greatly different (C20-C60), the ability of the lining concrete to bear the temperature difference is also greatly different, and the allowable value range of 20-25 ℃ is not enough to reflect the large strength difference. Therefore, it is necessary to newly study the allowable temperature difference between the lining concrete and the cooling water.

The comprehensive situation shows that the currently adopted water cooling method for controlling the internal temperature of the concrete with the lining structure has poor scientificity of water cooling water temperature control (allowable temperature difference between concrete and cooling water), no theoretical support, obvious unreasonable performance and poor guarantee of concrete temperature crack control.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for controlling water temperature of water to be introduced into concrete of a lining structure, which can scientifically control cracks in the concrete of the lining structure by introducing water to cool the concrete.

In order to achieve the purpose, the invention adopts the following scheme:

as shown in fig. 3, the present invention provides a method for controlling water temperature of concrete with a lining structure by water cooling, which is characterized by comprising the following steps:

step 1, collecting data for temperature control of lining concrete;

step 2, calculating water-feeding cooling control water temperature based on the collected lining concrete temperature control data, comprising the following steps:

step 2-1, calculating the allowable temperature difference (delta T) between the lining concrete and the cooling water according to the formula 1_cw】

【△T_cw2H +0.6C (formula 1),

in the formula: h is the thickness (m) of the lining concrete structure, and C is the strength grade (MPa) of the lining concrete;

step 2-2, calculating the lowest value T of the water cooling water temperature_w,min

T_w,min＝T_max-【△T_cwIs that (formula 2),

in the formula: t is_maxThe highest temperature (DEG C) in the lining concrete is adopted;

step 2-3, determining the water cooling control water temperature T_w

According to the water temperature condition which can be passed through in the construction site, the lowest value T of the water temperature of the water cooling system is calculated in a combined manner_w,minIs required to satisfy T_w≥T_w,minOn the premise of determining the water temperature T for water cooling control_w(ii) a In practical engineering, normal temperature tap water and water temperature T are usually adopted_cDetermined by nature, if the water temperature T is_cSatisfies the condition of being more than or equal to T_w,minThen can be directly adopted, i.e. T_w＝T_c。

Step 3, controlling the water temperature T according to the cooling of water_wAnd water cooling is carried out on the concrete with the building structure, so that temperature control and crack prevention are realized.

Preferably, the method for controlling the temperature of the concrete with the lining structure by water cooling can further have the following characteristics: the step 1 comprises the following steps: step 1-1, the basic data of the lining structure engineering is sorted and analyzed, and the method comprises the following steps: collecting design, construction and supervision data related to temperature control, crack prevention and water cooling of lining concrete; step 1-2, analyzing the technical requirements of temperature control design of lining concrete, comprising the following steps: the concrete temperature control, the allowable maximum temperature and the temperature control anti-cracking measures.

Further, the method for controlling the temperature of the concrete with the lining structure by water and cooling water provided by the invention can also have the following characteristics: the step 1 further comprises: in step 2-3, T_w＝T_w,min+1 to 5 ℃. Since the temperature of normal-temperature tap water is generally high and can meet the requirements, normal-temperature water is generally used for water cooling in a project. Since the temperature of the normal temperature water is generally high, the effect of cooling the water is poor. In some projects (such as the Raway tunnel flood spillway), in order to further improve the effect of reducing the internal temperature of the concrete by water cooling, a special refrigerating water system is adopted for water cooling, at the moment, the water temperature needs to be controlled not to be too low, and the water temperature is preferably controlled to be T_w＝T_w,minWithin the range of +1 to 5 ℃.

Preferably, the method for controlling the temperature of the concrete with the lining structure by water cooling can further have the following characteristics: the water temperature is reduced as much as possible in the temperature rise stage, so that the highest temperature in the lining concrete is reduced; in the temperature reduction stage, according to the water temperature T meeting the requirements of the step 2-3_wAnd water is introduced for cooling, the temperature drop speed is controlled, and internal cracks caused by too fast temperature drop are avoided.

In addition, the calculation formula 1 of the allowable temperature difference between the lining concrete and the cooling water is obtained by creative research on the principle that the influence rule of the water temperature control of the lining concrete on temperature, temperature stress and temperature cracks is obtained by adopting three-dimensional finite element method simulation calculation by combining the lining concrete with different structural thicknesses and different strengths (two main parameters) such as the Xiluou, the white Crane beach, the Wudongde 3 giant hydropower station engineering flood discharging holes, the power generation holes and the like and the principle of not reducing the anti-cracking safety coefficient, and the creative research comprises the following processes.

1. Different thickness lining concrete water cooling allowable water temperature difference [ Delta T_cwResearch on

The control of water cooling water temperature is realized by controlling the temperature gradient of concrete around a water pipe, so that cracks of the concrete around the pipe caused by an excessive temperature gradient are avoided; secondly, the temperature drop speed is controlled to avoid the over-fast production of the temperature drop speedThe ultra-strong tensile stress causes concrete cracks. The initial water temperature is lower because the temperature rise phase, the concrete expansion, the objective is to lower the maximum concrete temperature, the greater the reduction, the better. In the temperature reduction stage, too low water temperature can cause too high temperature reduction speed and too large temperature gradient of concrete around the pipe, so the water temperature must be controlled. Calculation shows that although the highest temperature and the maximum internal surface temperature difference inside the concrete can be reduced by adopting low water temperature all the time, the temperature of the concrete is reduced too fast due to too low water temperature, so that the temperature difference between a water pipe and nearby concrete is too large, the tensile stress inside the concrete is obviously increased in the water passing period, and the anti-cracking safety coefficient is reduced instead. Thus, with C ₉₀25 normal concrete is taken as an example, and the control research of the water flowing and cooling water temperature of lining concrete with different thicknesses is carried out. Firstly, low-temperature water (8 ℃) is adopted in the temperature rise stage, and normal-temperature water (the water temperature is controlled, namely the difference between the highest temperature of concrete and the water temperature is controlled) at 22 ℃ is adopted in the temperature drop stage; the second scheme is that low-temperature water (constant at 8 ℃) is adopted in the whole process. Through comparison, research suggests that the water cooling allowable water temperature difference (delta T) of lining concrete with different thicknesses_cw[ MEANS FOR solving PROBLEMS ] is provided. The characteristic values of the stress of each lining middle point and the minimum crack resistance safety coefficient under the two water passing schemes are arranged and listed in the following table 1; water cooling (temperature drop stage) of linings of different thicknesses_cwTable 2 below.

TABLE 1 characteristic values of stress and minimum crack resistance safety coefficient of each lining intermediate point under two water-passing schemes

TABLE 2 different thickness lining water cooling (temperature drop stage) allowable water temperature difference [ Delta T_cw】

The results show that: no matter which lining thickness is adopted, compared with the constant low water temperature water passing scheme, the maximum tensile stress in the curing period is obviously reduced and the crack resistance safety coefficient is obviously improved after the segmented water passing scheme is adopted. Therefore, the scientific approach is: in the temperature rise stage, the water temperature is lowered as much as possible, and the highest temperature is lowered; in the temperature drop stage, the water temperature is controlled, so that the temperature drop speed is controlled, and internal cracks caused by too fast temperature drop are avoided.

From Table 2 above, C ₉₀25, controlling the water temperature difference delta T in the temperature reduction process of the normal concrete in the concrete_cw＝17℃～19℃。

2. Different strength lining concrete water cooling allowable water temperature difference (delta T)_cwResearch on

(1)C ₉₀30 medium thermal lining concrete water cooling allowable water temperature difference [ Delta T ]_cwResearch on

To C ₉₀30, respectively carrying out simulation calculation on three conditions of lining thickness of 1.0m, 1.5m and 2.0m, constant water temperature and sectional water passing scheme, and finishing characteristic values of a temperature field and a stress field for comparative analysis. Wherein: thickness C of 1.0m₉₀The temperature, temperature stress and minimum crack resistance safety factor of 30 concrete constant water temperature and subsection water temperature are listed in the following table 3; thickness C of 1.5m₉₀The temperature, temperature stress and minimum crack resistance safety factor of 30 concrete constant water temperature and subsection water temperature are listed in the following table 4; 2.0m thickness C₉₀The temperature, temperature stress, minimum crack resistance safety factor for 30 concrete constant water temperature and segmental water temperature are listed in table 5 below.

TABLE 31.0 m thickness C ₉₀30 concrete constant water temperature and subsection water temperature, temperature stress and minimum crack resistance safety coefficient

TABLE 41.5 m thickness C ₉₀30 concrete constant water temperature and subsection water temperature, temperature stress and minimum crack resistance safety coefficient

TABLE 52.0 m thickness C ₉₀30 concrete constant water temperature and subsection water temperature, temperature stress and minimum crack resistance safety coefficient

According to the above calculation results, sorting C₉₀The difference between the water temperature of the 30-lined concrete section and the allowable water temperature of the concrete temperature reduction section is shown in the following table 6.

TABLE 6C₉₀30-lining concrete subsection water temperature and concrete temperature reduction stage allowable water temperature difference

C

₉₀30 lining concrete, wherein the water temperature difference delta Tcw of the concrete with the thickness of 1.0m is equal to 20 ℃; the water temperature difference delta Tcw of concrete with thickness of 1.5m and 2.0m is 23 ℃ and 25 ℃. Ratio C₉₀The 25-lined concrete is obviously improved, and the thickness is large and higher.

(2)C₉₀Water cooling allowable water temperature difference [ Delta T ] of 40 medium thermal lining concrete_cwResearch on

Same pair C

₉₀40, respectively carrying out simulation calculation on three conditions of lining thickness of 1.0m, 1.5m and 2.0m, constant water temperature and sectional water passing scheme, and finishing characteristic values of a temperature field and a stress field for comparative analysis. Wherein: thickness C of 1.0m, 1.5m, 2.0m₉₀The temperature, temperature stress, minimum crack resistance safety factor for 40 concrete constant water temperature and segmental water temperature are listed in tables 7 to 9 below.

TABLE 71.0 m thickness C₉₀Temperature, temperature stress and minimum crack resistance safety factor of 40 concrete constant water temperature and sectional water temperature

TABLE 81.5 m thickness C₉₀Temperature, temperature stress and minimum crack resistance safety factor of 40 concrete constant water temperature and sectional water temperature

TABLE 92.0 m thickness C₉₀Temperature, temperature stress and minimum crack resistance safety factor of 40 concrete constant water temperature and sectional water temperature

According to the above calculation results, sorting C₉₀The difference between the water temperature of the 40 lined concrete sections and the allowable water temperature of the concrete temperature drop sections is shown in table 10 below.

TABLE 10C

₉₀40 lining concrete subsection water temperature and concrete temperature reduction stage allowable water temperature difference

C

₉₀40 lining concrete, 1.0m thick concrete water temperature difference delta T_cwThe temperature is 28 ℃; water temperature difference delta T of concrete with thickness of 1.5m and 2.0m_cwAt 29 ℃. Is larger than the control value of dam concrete. Therefore, controlling the water temperature is related to the concrete strength and has a small relation to the adopted thickness.

3. Temperature difference [ Delta T ] allowed in temperature reduction stage of water cooling of lining concrete_cwComprehensive research

Synthesis of above C ₉₀25、C ₉₀30、C₉₀The research result of the allowable water temperature difference of the 40 lining concrete subsection water temperature and the concrete temperature reduction stage is obtained to obtain the maximum concrete temperature T_maxTemperature T of the cooling water_wAllowable temperature difference [ Delta T ]_cw Equation 1 is calculated.

Action and Effect of the invention

(1) The method of the invention can be suitable for controlling the water temperature of the water cooling of the lining concrete in any lining structure (comprising different civil engineering types, different structural forms, different thicknesses, different strengths and the like).

(2) The method scientifically realizes the water temperature control of the water cooling of the lining concrete. Water cooling is conducted to control water temperature difference (concrete highest temperature T)_maxTemperature T of the cooling water_wAllowable temperature difference [ Delta T ]_cwEquation 1), directly reflects the influence of lining thickness and intensity, avoids manual control errors, reduces labor intensity, avoids temperature cracks caused by water cooling at too low water temperature, and ensures the temperature control quality of water cooling at proper water temperature.

(3) The method has strong scientific property. The water temperature for water cooling is scientifically and reasonably controlled, the water temperature is as low as possible in the temperature rise stage, and the highest temperature is reduced; the water temperature is controlled in the temperature drop stage, so that the temperature drop speed is controlled, and internal cracks caused by too fast temperature drop are avoided. The temperature of the lining concrete can not rise again, the temperature control quality is ensured, the most effective temperature stress reduction in the whole process is realized, and the anti-cracking target is realized.

Drawings

Fig. 1 is a diagram of a crack of a flood discharging tunnel of a three-plate stream power station related to the background art, wherein (a) is an overall diagram, and (b) is a partially enlarged diagram;

FIG. 2 is a field diagram of a concrete water cooling water pipe lining the side wall of a flood discharge hole of a white crane beach hydropower station according to an embodiment of the invention;

FIG. 3 is a flowchart of a method for controlling water temperature of concrete water cooling of a lining structure according to an embodiment of the present invention;

FIG. 4 shows a graph 2 according to an embodiment of the present invention^#A structural section diagram of a 4 th unit of the flood discharge tunnel;

FIG. 5 shows a graph 2 according to an embodiment of the present invention^#An actual measurement curve diagram of the internal temperature of the lining concrete of the 4 th unit of the flood discharge tunnel;

FIG. 6 shows a white crane beach hydroelectric station 2 according to an embodiment of the present invention^#A cross section diagram of the lining of the flood discharging tunnel 139 unit;

FIG. 7 shows a white crane beach hydroelectric station 2 according to an embodiment of the present invention^#The spillway tunnel 139 unit is lined with concrete temperature over time.

Detailed Description

Hereinafter, the white crane beach hydropower station 2 shown in figure 2 is combined with the attached drawings^#Concrete is lined in the flood discharging hole 139 unit as an example, and a concrete embodiment of the concrete water-through cooling water temperature control method for the lining structure according to the present invention will be described in detail.

< temperature control data of lining concrete for flood discharge tunnel engineering of hydropower station in white crane beach >

1. Overview of the engineering

The white crane beach hydropower station is located in Ningnan county of Sichuan province and Qiaojia county of Yunnan province downstream of the Jinshajiang river, and is a control project for developing and governing Yangtze river. The installed capacity of the power station is 14004MW, the average power generation amount is 602.41 hundred million kW.h for many years, and the power station is the 2 nd hydropower station (next to 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 barrage is a concrete hyperbolic arch dam with the maximum dam height of 289.0 m. The flood discharge facility comprises 6 surface holes of a dam, 7 deep holes and 3 flood discharge tunnels on the left bank. The underground plant system adopts a head development scheme, the head development scheme is respectively and symmetrically arranged on the left bank and the right bank, and 8 hydroelectric generating sets are respectively installed in the plant.

The underground engineering comprises a diversion tunnel, a flood discharge tunnel, a power generation and water delivery system and the like. The diversion tunnel engineering is operated by water. 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 flood discharge tunnel non-pressure section and a flood discharge tunnel falling tail section, which are all of urban portal-shaped sections 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.

2. Maximum temperature allowed by concrete design and temperature control measure requirements

The allowable design maximum temperature of the flood tunnel lining concrete is shown in table 11 below:

table 11 maximum temperature unit allowed during construction period of flood discharge tunnel lining low-heat concrete: c

The concrete is subjected to temperature control in the whole process of pouring and curing, concrete cracking is avoided, and the following measures can be adopted (without limitation):

(1) the mixing proportion of the concrete is optimized, and the crack resistance of the concrete is improved. When the concrete mixing ratio is designed and concrete construction is carried out, the main design indexes such as concrete grade, frost resistance, impermeability and ultimate tensile value are met, and the construction homogeneity index and the strength guarantee rate are also met. Meanwhile, construction management should be enhanced, construction process should be improved, concrete performance should be improved, and concrete crack resistance should be improved.

(2) And reasonably arranging concrete construction procedures and construction progress. The concrete construction procedure and the construction progress should be reasonably arranged, and the construction management level should be improved in an effort.

(3) And controlling the highest temperature in the concrete. The effective measures include reducing the concrete pouring temperature, reducing the hydration heat temperature rise of the cementing material, leading water in the initial stage and the like. 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. When concrete at each part is poured, if the poured concrete temperature can not meet the relevant requirements, a supervisor is immediately informed, the concrete is processed according to the instruction of the supervisor, and effective measures are immediately taken to control the concrete pouring temperature.

3. Cooling water pipe burying

(1) The flood discharge tunnel flow passage lining concrete needs to embed a cooling water pipe for water cooling. The cooling water pipes are horizontally embedded and arranged in a row along the plane of the lining, and the distance between the cooling water pipes is 1.0-1.5 m.

(2) The concrete cooling water pipe can adopt a high-density polyethylene cooling water pipe, and the outer diameter of the high-density polyethylene cooling water pipe

The wall thickness was 2mm, as indicated in Table 12 below.

TABLE 12 high Density polyethylene Cooling Water pipe indices

(3) The arrangement of the concrete cabin surface cooling water pipes is carried out according to the design drawing of a contractor approved by a supervisor or the instruction of the supervisor, and the arrangement, the connection and the heat preservation of the water supply main branch pipes are determined by the contractor according to the situation of a construction site, but must be approved by the supervisor. The stable temperature of the concrete, the concrete cooling speed, the cooling procedure and the temperature monitoring method are carried out according to relevant regulations or instructions of a supervisor.

(4) Oil stains and the like on the surface of the cooling water pipe are to be removed. The length of a single circulating cooling water pipe is generally not more than 250 m. The pre-buried cooling water pipe cannot cross the contraction joint.

(5) All pipes are tightened or braced by metal pieces in a manner approved by a proctoring person. All joints of the water pipe should have water tightness, and the water pipe should be cleaned under the condition that a supervisor is present, and the joint should not leak water under the hydrostatic pressure of 0.35MPa when the water pipe is buried.

(6) Before concrete pouring, circulating water with the pressure not lower than 0.2MPa is introduced into the cooling water pipe for inspection. The resistance condition in the pipe is indicated by a pressure gauge and a flowmeter at the same time. The water tubes should be carefully protected to prevent shifting or damage to the cooling water tubes during concrete placement or other work after placement and during testing. The pipe head extending out of the concrete should be protected by a capping method and the like.

(7) The connection with each cooling water pipe should be effective at any time to can install and demolish fast, the circulating water that does not influence other cooling water pipes simultaneously need reliably to control the rivers of a certain water pipe. The inlet and outlet ends of all water pipes should be marked clearly to ensure that the cooling water can flow in the right direction in the whole cooling process. The arrangement of the header pipes is such that the positions of the pipe heads are easily switched with respect to the direction of water flow in the cooling water pipes. The direction of the cooling water flow was reversed every 24 h. The contractor should maintain a written record and report the following to the proctor weekly: water pressure, and the flow and temperature of water flow at the water inlet end and the water outlet end of each cooling water pipe.

(8) In the concrete pouring process, a special person needs to maintain the pipeline so as to prevent the pipeline from deforming or being blocked. After the concrete is buried by 30-60 cm, water (gas) is introduced for inspection, problems are found, and the concrete is treated in time. If any damage is done to the cooling water pipe during the concrete pouring process, the concrete pouring should be stopped immediately until the cooling water pipe is repaired and can continue after the test.

4. Cooling by water

Water is introduced for cooling and the water temperature is: generally, 18 ℃ refrigeration water or clean river water (the temperature of the river water is not more than 22 ℃), the temperature difference between the concrete temperature and the cooling water is not more than 25 ℃, the daily temperature reduction range of the concrete is not more than 2 ℃ during cooling, and the water flow direction is changed once a day, so that the concrete blocks are uniformly cooled. The water is designed to be supplied for 7 to 20 days.

5. Temperature measurement

(1) The temperature measurement of concrete should be performed using a resistance thermometer or a thermocouple buried in the concrete. In the construction period, one bin is selected for every 10 pouring bins, at least 1 pouring bin is selected for each building every month, construction period thermometers are buried in the pouring bins, 1-3 thermometers are buried in the pouring bins, and thermometers are additionally arranged if necessary.

(2) Temperature measurement reports should be recorded and submitted to the supervisor once a week, including (but not limited to): concrete pouring temperature, concrete internal temperature, cooling water flow of each cooling water pipe, flow direction, pressure, inlet temperature, outlet temperature and other measurement indexes required by a supervisor.

(3) In the concrete construction process, the outlet concrete temperature, the warehousing temperature, the pouring temperature and the temperature of the casting body cooling water are measured at least every 4 hours for 1 time and recorded.

(4) Measurement of concrete casting temperature per 100m²The area of the warehouse surface is not less than 1 measuring point, and each 1 pouring layer is not less than 3 measuring points. The measuring points should be evenly distributed on the pouring layer surface.

(5) After the thermometer is installed, the contractor should calibrate, observe, and record the initial readings of the equipment in the operating state, as approved by the supervisor. The temperature is measured within 24h after the temperature gauge is buried, 1 time is carried out every 4h, and then 3 times are carried out every day until the concrete reaches the highest temperature. The observation was performed 1 time per day for one ten days. And observing for 1 time every two days for 1 month, and observing for the rest of time period once a month.

Example 1^#Water cooling of lining concrete of fourth unit of flood discharge tunnel

As shown in FIG. 4, 2^#The thickness of the fourth unit lining structure of the upper flat section of the flood discharge tunnel is 2.5m and is C ₉₀40 low heat concrete. The side wall lining concrete is poured in 2017, 5, month and 12, for example.

As shown in fig. 3, the method for controlling water temperature of concrete with lining structure through water and cooling water provided by this embodiment includes the following steps:

step 1, analyzing temperature control data of lining concrete, and determining a water cooling temperature control scheme:

step 1-1, the basic data of the lining structure engineering are sorted and analyzed. 2^#Basic data of a fourth unit lining structure of the upper flat section of the flood discharge tunnel comprise temperature control anti-cracking, water cooling, design technical requirements and the like. As the flood discharge tunnel of the hydropower station of the white crane beach is a level 1 building, the water flow speed reaches nearly 50m/s to the maximum extent, and the temperature control and crack prevention of the lining concrete are very important. Depending on design requirements, effective measures including water cooling for temperature control are required.

Step 1-2. temperature control device for analyzing lining concreteAnd (6) counting the technical requirements. The concrete temperature control method comprises the technical requirements of concrete temperature control, allowable maximum temperature, temperature control anti-cracking measures and the like. Based on the above engineering data of the hydropower station in the white Crane beach, 2^#Concrete is lined in the fourth 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 in 2017, 5 months and 12 days, and according to the design requirements of table 7, the allowable maximum temperature of lining concrete with the thickness of 2.5m is 42 ℃.

【△T_cw2H +0.6C (formula 1),

in the formula: h is the thickness of the lining concrete structure, and C is the strength grade of the lining concrete;

substituting the thickness H of the lining concrete structure of 2.5m and the strength grade C of the lining concrete of 40(MPa) into the formula 1, and calculating to obtain [ Delta T ]_cw】＝29℃。

T_w,min＝T_max-【△T_cwIs that (formula 2),

in the formula: t is_maxAccording to similar engineering experience, pouring lining concrete with the thickness of 2.5m in the middle of 5 th of a month for lining the highest temperature in the concrete, and predicting C₉₀The 40 low heat concrete internal design allows a maximum temperature of 42 ℃.

Will T_max＝42℃，【△T_cwSubstituting 29 deg.C into equation 2 to calculate T_w,min＝13℃。

Step 2-3, determining the water cooling control water temperature T_w

According to the water temperature condition which can be passed through in the construction site, the lowest value T of the water temperature of the water cooling system is calculated in a combined manner_w,minIs required to satisfy T_w≥T_w,minOn the premise of determining the water temperature T for water cooling control_w；

According to T_w＝T_w,min+1～5℃，T_wPreferably between 14 ℃ and 18 ℃, in this example, T is used_wCold water at 18 ℃.

Step 3, determining a water cooling temperature control scheme, and controlling the water temperature T according to the water cooling_wAnd water cooling is carried out on the concrete with the building structure, so that temperature control and crack prevention are realized.

Water cooling water pipe arrangement, flow control, etc., as described above. Arranging water-cooling water pipes, and arranging single-layer water pipes (shown in figure 2) at the interval of 1.5m along the axis (lining plane) of the side wall; the flow rate of water is 48m³And d, controlling. Introducing water to cool water, and taking T_wCold water at 18 ℃.

According to the determined water cooling temperature control scheme, a water cooling water pipe (and a control switch thereof) is arranged before the pouring of lining concrete, and water cooling is carried out after the pouring of concrete. The water temperature of the water cooling is controlled to be T_w18 ℃. See Table 13 below for the results arrangement.

Watch 132^#Fourth unit lining concrete pouring actual measurement data

The internal temperature water cooling control result of lining structure concrete is arranged and analyzed:

2^#pouring concrete of a fourth unit lining structure of the upper horizontal section of the flood discharging tunnel in 2017, 5, month and 12 days, adopting a water cooling measure in the construction, and carrying out water cooling according to the temperature control scheme and the water cooling time of 10 days.

The main actual measurement temperature control data is shown in table 13 according to the construction record, and the actual measurement lining concrete internal temperature curve is shown in the solid line of fig. 5. Simulation calculation of water cooling 7d is also performed by the finite element method, and the internal temperature curve of the concrete is shown by a dotted line in fig. 5.

The above results show that:

(1) water cooling water temperature T_w18 ℃ and the difference with the maximum temperature in the concrete of 41.87 ℃ is 23.87 ℃ and less than 29 ℃, namely T_wHigher than 13 ℃ to meet the requirement. At the same time T_wThe temperature is 13+5 ℃ which is 18 ℃, which is the upper limit of the suggested value, and the water is cooled reasonably by water.

(2) The maximum temperature in the lining concrete is 41.87 ℃ and is less than the design allowable value of 42 ℃, the design technical requirements are met, and the temperature control target is realized. Namely, the water cooling obtains good effect.

(3) The temperature drop speed of the lining concrete is reduced to 34.7 ℃ from 41.87 ℃ to 9d of 3.5d, the average temperature drop speed is 1.3 ℃/d and is less than 2.0 ℃/d, and the requirement is met. Namely, the water temperature is not too low, and the temperature reduction speed of the concrete is reasonably controlled.

(4) Observation for 3 months by 2019 shows that 2^#The concrete of the fourth unit lining structure of the upper flat section of the flood discharge tunnel has no crack, and the temperature control and crack prevention effect is good.

(5) The water temperature control of the water cooling is carried out by calculating the allowable water temperature difference according to the scheme, and the method is scientific and reasonable.

EXAMPLE 2^#Water cooling of lining concrete of fourth unit of flood discharge tunnel

2^#139 th unit of flood discharge tunnel body, lining in the shape of an urban portal, lining with side walls with the thickness of 1.5m, arranging annular construction joints every 12m along the axial direction of the flood discharge tunnel, arranging IV-class surrounding rocks, and arranging a bottom plate and side walls of a lining structure to be C ₉₀40 low heat cement concrete with C top arch₉₀30 low heat cement concrete, as shown in fig. 6. The basic data of temperature control are the same as above. The pouring temperature of the concrete is designed to be 18 ℃, normal-temperature tap water is adopted for moisturizing and curing for 90 days, and water is introduced for cooling to control the internal temperature of the concrete. Pouring in the pouring way in 2018, 11, 12 months.

step 1, analyzing temperature control data of lining concrete and determining a water cooling temperature control scheme

Step 1-1, the basic data of the lining structure engineering are sorted and analyzed. 2^#Basic data of a 139 th unit lining structure of the upper flat section of the spillway tunnel comprise temperature control and crack prevention, water cooling, design technical requirements and the like. As the flood discharge tunnel of the hydropower station of the white crane beach is a level 1 building, the maximum water flow speed reaches nearly 50m/sThe temperature control and crack prevention of the lining concrete are very important. Depending on design requirements, effective measures including water cooling for temperature control are required.

Step 1-2, analyzing the technical requirements of temperature control design of lining concrete. Based on the above engineering data of the hydropower station in the white Crane beach, 2^#Concrete is lined in the 139 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 in 2018, 11, 9 days, and according to the design requirements of the table 11, the allowable maximum temperature of the lining concrete with the thickness of 1.5m is 38 ℃.

【△T_cw2H +0.6C (formula 1),

substituting the thickness H of the lining concrete structure of 1.5m and the strength grade C of the lining concrete of 40(MPa) into the formula 1, and calculating to obtain [ Delta T ]_cw】＝27℃。

T_w,min＝T_max-【△T_cwIs that (formula 2),

in the formula: t is_maxAccording to similar engineering experience, pouring lining concrete with the thickness of 1.5m in 11 middle-of-the-month to line the highest temperature in the concrete, and predicting C₉₀The 40 low heat concrete internal design allows a maximum temperature of 38 ℃.

Will T_max＝38℃，【△T_cwWhen equals 27 ℃, substitute formula 2, calculate T_w,min＝11℃。

Step 2-3, determining the water cooling control water temperature T_w

According to the water temperature condition which can be passed through in the construction site, the lowest value T of the water temperature of the water cooling system is calculated in a combined manner_w,minIs required to satisfy T_w≥T_w,minOn the premise of (1), determineWater cooling control water temperature T_w；

According to T_w＝T_w,min+1～5℃，T_wPreferably between 12 ℃ and 16 ℃, and about 16 ℃ according to local hydrological data, the temperature of 11 months river water, so in this embodiment, T is adopted_wAnd (4) cooling the river water at 16 ℃ by introducing water.

Water cooling water pipe arrangement, flow control, etc., as described above. Arranging water-cooling water pipes, and arranging single-layer water pipes (shown in figure 2) at the interval of 1.5m along the axis (lining plane) of the side wall; the flow rate of water is 48m³And d, controlling. Introducing water to cool water, and taking T_wClean river water at 16 ℃.

According to the determined water cooling temperature control scheme, a water cooling water pipe (and a control switch thereof) is arranged before the pouring of lining concrete, and water cooling is carried out after the pouring of concrete. The water temperature of the water cooling is controlled to be T_w16 ℃. The method is concretely finished product arrangement.

2^#and (3) lining the side wall of the cave body of the leveling tunnel with the 139 th unit concrete pouring time period: 2018.11.9(07:50) -2018.11.10(14:20). Flood discharge tunnel 2^#The arrangement of the concrete water-through cooling water pipe of the 139 th unit lined on the side wall of the structural section is shown in figure 2. 2 thermometers were mounted in place on 11/8 am, 2018. The environmental temperature, the concrete warehousing temperature and the pouring temperature during the concrete pouring are monitored in the whole process of the construction unit, and the results are listed in table 14. The average value of the ambient temperature is 15.9 ℃, the average value of the concrete warehousing temperature is 12.8 ℃, and the average value of the concrete pouring temperature is 14.6 ℃. The water cooling adopts normal temperature water at about 16 ℃.

TABLE 14 statistical table for temperature of No. 2 spillway tunnel side wall lining 139 th unit of white crane beach hydropower station

Pouring concrete starts to submerge the thermometer in 2018, 11, 9:00 and water cooling starts to be carried out. 2^#And (3) temperature when the side wall of the cave body of the leveling tunnel is lined with the 139 th unit concrete: the left wall was 15.0 ℃ and the maximum temperature of 29.8 ℃ was reached over 41 hours with a maximum temperature rise of 14.8 ℃. As shown in fig. 7.

The above results show that:

(1) according to the prior design, the water is introduced for cooling the water temperature T_w16 ℃ (16 ℃ in clean river water), and the temperature difference of 38 ℃ with the maximum temperature allowed by design is 22 ℃, and is less than [ Delta T ]_cwAt 27 ℃ and T_w＝16℃＝T_w,minAnd the temperature of +5 ℃ is the upper limit of the suggested value, and the water cooling water is reasonably designed. During construction, the maximum temperature inside the concrete is measured to be 29.8 ℃, the actual water temperature difference is 29.8-16-13.8 ℃, and is smaller than delta T_cw27 ℃ meets the requirement. But according to the measured maximum internal concrete temperature T_w29.8 ℃ and [ Delta T_cwThe cooling can be carried out by introducing water at a lower water temperature (29.8-27 is 2.98 ℃, and then 1-5 ℃ water can be adopted) and cooling at 27 ℃. If water (namely refrigeration water) with the temperature lower than 4-8 ℃ is adopted for water cooling, the maximum temperature of the concrete can be further reduced, a better temperature control effect is obtained, but the refrigeration cost needs to be increased. The results show that the water cooling is carried out at normal temperature (16 ℃ of clean river water), the refrigeration cost is not needed, the temperature control target is achieved (the maximum temperature is 29.8 ℃ and is less than the design allowable value of 38 ℃), the water cooling with lower water temperature is not needed at all, the refrigeration cost can be saved, and the water temperature is reasonable.

(2) The measured maximum temperature inside the concrete is 29.8 ℃, which is far less than the allowable designed maximum temperature of 38 ℃, and the maximum temperature inside the concrete is effectively controlled. The water cooling temperature control effect is good.

(3) The temperature is reduced from 41h to 205h for 8.5d, the total temperature is reduced by 11.5 ℃, the temperature reduction speed in the actual temperature reduction process is 1.35 ℃/d and is less than 2.0 ℃/d, and the average temperature reduction speed is effectively controlled. Namely, the water temperature is not too low, and the temperature reduction speed of the concrete is reasonably controlled.

(4) Water is introducedCooling flow rate 48m³D, meeting the design technical requirements;

(5) white crane beach hydropower station 2^#The 139 th unit concrete is lined on the side wall of the cave body of the leveling tunnel, and the temperature crack period is possibly generated in winter by 3 months in 2019, no crack is generated, and the remarkable temperature control and crack prevention effects are achieved.

The above results show that:

(1) actually measuring the highest temperature inside the concrete to be 29.8 ℃, wherein the highest temperature is far less than the allowable designed highest temperature of 38 ℃, and effectively controlling the highest temperature inside the concrete;

(2) the temperature is reduced from 41h to 205h for 8.5d, the total temperature is reduced by 11.5 ℃, the temperature reduction speed in the actual temperature reduction process is 1.35 ℃/d and is less than 2.0 ℃/d, and the average temperature reduction speed is effectively controlled;

(3) the average casting temperature is 14.6 ℃ and less than 18 ℃, and the design technical requirements are met;

(4) the temperature of the water is 16 ℃ and the difference between the water and the highest temperature in the concrete is 29.8 ℃ and is less than 25 ℃, so that the design technical requirement is met;

(5) cooling water flow rate of 48m³D, meeting the design technical requirements;

(6) white crane beach hydropower station 2^#The 139 th unit concrete is lined on the side wall of the cave body of the leveling tunnel, and the temperature crack period is possibly generated in winter by 3 months in 2019, no crack is generated, and the remarkable temperature control and crack prevention effects are achieved.

The results of the above examples show that the method of the present invention can be applied to control the water temperature of water-through cooling water in lining concrete in any lining structure (including different civil engineering types, different structural forms, different thicknesses, different strengths, etc.).

The method is scientific, the calculation formula 1 of the allowable temperature difference between the water cooling lining concrete and the cooling water directly reflects the influence of the lining thickness and the strength grade, and the water cooling temperature control quality is ensured.

The method scientifically and reasonably controls the water temperature for water cooling, lowers the water temperature as much as possible in the temperature rise stage, and lowers the highest temperature; the water temperature is controlled in the temperature drop stage, so that the temperature drop speed is controlled, and internal cracks caused by too fast temperature drop are avoided. The temperature of the lining concrete can not rise again, the temperature control quality is ensured, the most effective temperature stress reduction in the whole process is realized, and the anti-cracking target is realized.

The above embodiments are merely illustrative of the technical solutions of the present invention. The method for controlling the temperature of water for cooling and water for concrete of lining structure according to the present invention is not limited to the contents described in the above embodiments, but is subject to the scope defined by the claims. Any modification or supplement or equivalent replacement made by a person skilled in the art on the basis of this embodiment is within the scope of the invention as claimed in the claims.

Claims

1. A water cooling and water temperature control method for concrete of a lining structure is characterized by comprising the following steps:

step 1, collecting data for temperature control of lining concrete;

【△T_cw=2H +0.6C (formula 1),

in the formula: h is the thickness of the lining concrete structure, and the unit is m; c is the strength grade of the lining concrete, and the unit is MPa;

step 2-2, calculating the lowest value T of the water temperature of the water cooling_w,min

T_w,min= T_max-【△T_cwIs that (formula 2),

in the formula: t is_maxLining the highest temperature inside the concrete;

step 2-3, determining the water temperature T for controlling water cooling_w

2. The method for controlling the temperature of concrete water for cooling water in a lining structure according to claim 1, wherein:

wherein, step 1 includes:

step 1-1, the basic data of the lining structure engineering is sorted and analyzed, and the method comprises the following steps: collecting design, construction and supervision data related to temperature control, crack prevention and water cooling of lining concrete;

step 1-2, analyzing the technical requirements of temperature control design of lining concrete, comprising the following steps: the concrete temperature control, the allowable maximum temperature and the temperature control anti-cracking measures.

3. The method for controlling the temperature of concrete water for cooling water in a lining structure according to claim 1, wherein:

wherein, in step 2-3, T_w=T_w,min+（1~5℃）。

4. The lining structure concrete water cooling water temperature control method according to claim 1 or 3, characterized in that:

wherein, the water temperature is reduced as much as possible in the temperature rise stage, so that the highest temperature in the lining concrete is reduced; in the temperature reduction stage, according to the water temperature T meeting the requirements of the step 2-3_wCooling with water and controlling the temperature reduction speed.