CN113818445A - Cooling control method and circulating cooling system for mass concrete structure in water body - Google Patents
Cooling control method and circulating cooling system for mass concrete structure in water body Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 271
- 239000004567 concrete Substances 0.000 title claims abstract description 158
- 238000001816 cooling Methods 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000000498 cooling water Substances 0.000 claims abstract description 176
- 230000001276 controlling effect Effects 0.000 claims abstract description 38
- 230000001105 regulatory effect Effects 0.000 claims abstract description 16
- 238000003860 storage Methods 0.000 claims description 16
- 238000004891 communication Methods 0.000 claims description 9
- 238000004458 analytical method Methods 0.000 claims description 5
- 238000009529 body temperature measurement Methods 0.000 claims description 5
- 238000010276 construction Methods 0.000 abstract description 32
- 239000008239 natural water Substances 0.000 abstract description 6
- 238000005086 pumping Methods 0.000 abstract 1
- 230000006641 stabilisation Effects 0.000 abstract 1
- 238000011105 stabilization Methods 0.000 abstract 1
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- 238000004321 preservation Methods 0.000 description 2
- 238000003908 quality control method Methods 0.000 description 2
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/06—Placing concrete under water
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D17/00—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces
- F25D17/02—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces for circulating liquids, e.g. brine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D29/00—Arrangement or mounting of control or safety devices
- F25D29/005—Mounting of control devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D2600/00—Control issues
- F25D2600/06—Controlling according to a predetermined profile
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Abstract
The embodiment of the application provides a cooling control method and a circulating cooling system for a mass concrete structure in a water body, and relates to the technical field of mass concrete construction, wherein in the cooling control method, after concrete covers a pre-buried cooling water pipe, water in the water body and water stored in a cofferdam area are respectively and successively extracted as circulating cooling water to circulate the cooling water pipe; when the monitored internal temperature of the concrete reaches a preset first temperature threshold value, pumping the water in the water body again as circulating cooling water; and meanwhile, regulating and controlling the water flow rate according to the temperature of each temperature measuring point obtained in real time until the concrete enters a stabilization period. According to the technical scheme, natural water resources around the large-volume concrete construction of the hydraulic engineering are utilized to realize the allocation of cooling water, the utilization rate of the water resources is improved, the investment of water supply equipment is reduced, and the quality and the efficiency of the engineering construction are ensured, so that the energy-saving and environment-friendly civilized construction requirement is met.
Description
Technical Field
The invention relates to the technical field of mass concrete construction, in particular to a cooling control method and a circulating cooling system for a mass concrete structure in a water body.
Background
The rapid development of economy drives the construction speed of infrastructure, hydraulic engineering is a project which is closely related to the life of people, so that the quality control is very critical in the construction process, the main material of the hydraulic engineering is reinforced concrete, large-volume concrete structures are used at the key parts of the engineering along with the complexity of the hydraulic engineering conditions and the higher and higher construction technical requirements, and the realization of the hydraulic building function is directly influenced by the quality control of the large-volume concrete construction technology.
The large-volume concrete is in the pouring process, because the temperature difference that cement heat of hydration arouses can be great, generally all be one shot forming at the pouring process, consequently gathering behind the cement heat of hydration after the shaping can't give out in the structure is inside, the inside temperature of concrete can be higher than outside temperature like this, the influence of inside and outside difference in temperature can lead to pressure to produce the bulging force, then great contractility can appear when the temperature ratio reduces, very easily lead to the production of concrete structure crack, seriously influence the safety of concrete structure.
At present, a lot of cooling control methods are adopted, namely cooling water pipes are buried in a large-volume concrete structure to be poured, and circulating cooling water is introduced into the cooling water pipes to realize the cooling of the concrete. Therefore, in order to meet the requirement of a large amount of cooling water required in the cooling process of the large-volume concrete, a cooling water allocation scheme needs to be configured, for example, a cooling water recycling device composed of a refrigeration system, a circulating water tank, a cold water conveying system, a return water collecting tank and the like, so that not only is certain construction cost required, but also the pressure of a refrigeration unit is very high, a large amount of energy is consumed, and the civilized construction requirement of energy conservation and environmental protection cannot be met.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a cooling control method and a circulating cooling system for a mass concrete structure in a water body, which utilize natural water resources around mass concrete construction of a hydraulic engineering to realize allocation of cooling water, improve the utilization rate of the water resources, reduce the investment of water supply equipment, and ensure the quality and efficiency of the engineering construction, thereby achieving the civilized construction requirements of energy saving and environmental protection.
In a first aspect, an embodiment of the present application provides a method for controlling cooling of a mass concrete structure in a water body, including the following steps:
when concrete is poured, after the concrete covers the pre-buried cooling water pipe, water in the water body and water stored in the cofferdam area are respectively and successively extracted to be used as circulating cooling water to carry out circulating water communication on the cooling water pipe, and the water flow rate is regulated according to the temperature of each temperature measuring point acquired in real time, so that the difference between the water inlet temperature and the water outlet temperature of the cooling water pipe is within a preset temperature difference range;
when the monitored internal temperature of the concrete reaches a preset first temperature threshold value, water in the water body is extracted again to serve as circulating cooling water, the water flow rate is regulated according to the temperature of each temperature measuring point obtained in real time until the internal temperature of the concrete is lower than a preset second temperature threshold value, and the temperature difference value between the internal temperature of the concrete and the surface temperature is lower than 25 ℃.
Further, when concrete is poured, after the concrete covers the pre-buried cooling water pipe, water in the water body and the water stored in the cofferdam area are successively extracted respectively to carry out circulating water communication on the cooling water pipe, and the method comprises the following steps:
after the concrete covers the pre-buried cooling water pipe, extracting water in the water body to carry out circulating water communication on the cooling water pipe, and storing water in the cofferdam area;
and after the water storage level of the cofferdam area reaches a preset height, extracting the stored water of the cofferdam area as circulating cooling water.
Further, before the internal temperature of the concrete reaches the first temperature threshold, the method further comprises the following steps:
and controlling the water in the cooling water pipe to switch the flow direction at a first preset time interval.
Further, the first preset time interval is 12 h.
Further, after the internal temperature of the concrete reaches the first temperature threshold, the method further comprises the following steps:
and controlling the water in the cooling water pipe to switch the flow direction at a second preset time interval.
Further, the second preset time interval is 24 h.
Further, the adjusting and controlling of the flow rate of the cooling water according to the temperature at each temperature measurement point obtained in real time includes:
calculating to obtain a temperature change rule of each temperature measuring point based on a pre-established finite element analysis model of the large-volume concrete structure;
calculating the water flow of the cooling water pipe in each time period based on the temperature change rule of each temperature measuring point and the actually measured temperature value;
and controlling the water flow speed in the cooling water pipe according to the water flow.
Further, the controlling the water flow rate in the cooling water pipe according to the water flow rate includes:
before the internal temperature of the concrete reaches the first temperature threshold value, controlling the water flow through variable speed of a frequency converter to enable the water in the cooling water pipe to be in a turbulent flow state;
after the internal temperature of the concrete reaches the first temperature threshold value, the water flow is controlled through the regulating valve, so that the water in the cooling water pipe is in a laminar state.
In a second aspect, embodiments of the present application provide a circulating cooling system for a mass concrete structure in a body of water, including: the system comprises a circulating cooling water pipe system, a temperature sensor group and a central controller; the central controller is respectively connected with the circulating cooling water pipe system and the temperature sensor group; wherein,
the temperature sensor group comprises a plurality of temperature sensors arranged in the mass concrete structure and is used for sending real-time temperature information to the central controller;
the central controller is used for controlling the circulating cooling water pipe system to regulate the flow of cooling water according to the real-time temperature information;
the circulating cooling water pipe system comprises at least one circulating cooling water pipe group and at least one water pump group which are horizontally laid in the large-volume concrete structure; each circulating cooling water pipe group comprises at least one cooling water pipe, and the cooling water pipe is a coiled pipe; each water pump group comprises at least two water pumps, the water inlet ends of the two water pumps are respectively communicated with a water body and the cofferdam area through external water pipes, and the water outlet ends of the two water pumps are connected with the water inlets of the cooling water pipes through double-channel switching devices; the double-channel switching device is connected with the central controller and used for controlling the switching and communication between the water inlet of the cooling water pipe and the water outlet ends of the two water pumps according to the switching instruction of the central controller.
Furthermore, the circulating cooling water pipe system comprises two or more circulating cooling water pipe groups; the vertical distance between two adjacent layers of circulating cooling water pipe groups is 1.0m, and the arrangement directions are mutually vertical; the distance between the parallel pipe bodies of each circulating cooling water pipe group is 1.0 m; and the distance between each circulating cooling water pipe group and the boundary of the concrete structure is not less than 0.5 m.
Furthermore, the water pump is a variable-frequency water pump, the circulating cooling water pipe system further comprises at least one frequency converter, each frequency converter is connected with the central controller and the two water pumps, and the frequency converter is used for adjusting the water yield of the currently working water pump according to a control instruction of the central controller.
According to the cooling control method and the circulating cooling system for the mass concrete structure in the water body, natural water resources around the mass concrete construction of the hydraulic engineering are utilized, and the water resources are regulated, stored, conveyed and distributed, so that the water circulation cooling in the mass concrete is realized, the utilization rate of the water resources is improved, the investment of water supply equipment is reduced, the quality and the efficiency of the engineering construction are ensured, and the civilized construction requirements of energy conservation and environmental protection are met; and the central controller is used for realizing real-time acquisition of temperature information, improving the working efficiency, automatically controlling the cooling water flow of the circulating cooling water pipe system and ensuring the implementation controllability, thereby ensuring the quality of concrete construction.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a circulating cooling system for a mass concrete structure in a body of water according to one embodiment;
FIG. 2 is a schematic view of the shape of a cable tower bearing platform template provided by the first embodiment;
FIG. 3 is a diagram of the arrangement of cooling water pipes in the template of the bearing platform of the cable tower provided by the first embodiment;
fig. 4 is a schematic flow chart of a cooling control method for a mass concrete structure in a water body according to the second embodiment.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
In some of the flows described in the specification and claims of this application and in the above-described figures, a number of operations are included that occur in a particular order, but it should be clearly understood that these operations may be performed out of order or in parallel as they occur herein, with the order of the operations being numbered, e.g., S11, S12, etc., merely to distinguish between various operations, and the order of the operations itself is not intended to represent any order of performance. Additionally, the flows may include more or fewer operations, and the operations may be performed sequentially or in parallel. It should be noted that, the descriptions of "first", "second", etc. in this document are used for distinguishing different messages, devices, modules, etc., and do not represent a sequential order, nor limit the types of "first" and "second" to be different.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.
It will be understood by those of ordinary skill in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, wherein the same or similar reference numerals refer to the same or similar elements or elements with the same or similar functions throughout. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In order to facilitate understanding of the technical solutions provided in the embodiments of the present application, a description will be given below of a circulating cooling system for a mass concrete structure in a water body according to the embodiments of the present application.
Example one
Referring to fig. 1, fig. 1 is a schematic structural diagram of a circulating cooling system for a mass concrete structure in a water body according to an embodiment. The circulation cooling system includes: the recirculated cooling water pipe system 10, the temperature sensor group 20, and the central controller 30; the central controller 30 is respectively connected with the circulating cooling water pipe system 10 and the temperature sensor group 20; wherein,
the temperature sensor group 20 comprises a plurality of temperature sensors 21 arranged in the mass concrete structure and used for sending real-time temperature information to the central controller 30;
specifically, the plurality of temperature sensors 21 are respectively disposed at each temperature measuring point in the formwork of the mass concrete structure, preferably, the temperature sensors 21 are wireless temperature sensors, are connected to the central controller 30 through wireless communication, and transmit the collected temperature to the central controller 30 in real time. Collecting the temperature values of all temperature measuring points in real time on site within the time from the pouring of the concrete to the end of water supply, and well recording the temperature values; the hydration heat temperature changes violently in the time (namely, the temperature rise period) from the concrete pouring to the time when the internal temperature of the concrete reaches the temperature rise peak value, so the time interval of data acquisition in the temperature rise period of the concrete is 2 hours, the time interval of data acquisition in the slow hydration heat temperature change (namely, the temperature decrease period) is adjusted to 4 hours, and the time interval of data acquisition in the stable decline period (namely, the stable period) is 10 hours.
The central controller 30 is configured to control the recirculated cooling water pipe system 10 to adjust the flow rate of the cooling water according to the real-time temperature information;
the circulating cooling water pipe system 10 comprises at least one circulating cooling water pipe group 11 and at least one water pump group 12 which are horizontally laid in the large-volume concrete structure; each of the circulating cooling water pipe groups 11 comprises at least one cooling water pipe 111, and the cooling water pipe 111 is a serpentine pipe; each water pump group 12 comprises at least two water pumps 121, the water inlet ends of the two water pumps 121 are respectively communicated with a water body and a cofferdam area through external water pipes, and the water outlet ends of the two water pumps 121 are connected with the water inlet of the cooling water pipe 111 through a double-channel switching device 13; the two-channel switching device 13 is connected to the central controller 30, and is configured to control the water inlet of the cooling water pipe 111 and the water outlet ends of the two water pumps 121 to be switched and communicated according to a switching instruction of the central controller 30.
Preferably, the pipe diameter of the cooling water pipe 111 is 35mm to 45 mm. The pipe diameter of the cooling water pipe is too large, so that the consumption of the pipe is increased, the construction cost is increased, and the influence on the cooling effect is not obvious; the pipe diameter of the cooling water pipe is too small, the resistance of the water pipe is increased, the working load of the water pump is increased, and the construction cost is also improved.
Preferably, the water pump 121 is a variable-frequency water pump, the recirculated cooling water pipe system 10 further includes at least one frequency converter 14, each frequency converter 14 is connected to the central controller 30 and the two water pumps 121, and the frequency converter 14 is configured to adjust the water output of the currently operating water pump according to a control instruction of the central controller 30. Specifically, the output end of the frequency converter 14 is connected to the two water pumps 121 through two contactors, and one of the two water pumps 121 is driven to operate by switching and starting the two contactors.
In the preferred embodiment, the water yield of the currently working water pump is controlled through the variable speed of the frequency converter 14, so that the energy loss can be effectively reduced, and the efficiency and the energy can be improved; and the frequency converter 14 has higher control precision and can accurately adjust the water flow pressure and the water flow.
It should be noted that the flow regulation of the water pump may also be realized by a regulating valve disposed on the water inlet pipeline of the cooling water pipe, and of course, other water pump flow regulation manners may also be adopted, which is not limited herein.
As an alternative embodiment, the recirculated cooling water pipe system 10 includes two or more recirculated cooling water pipe groups 11; the vertical distance between two adjacent layers of circulating cooling water pipe groups 11 is 1.0m, and the arrangement directions are mutually vertical; the distance between the parallel pipe bodies of each circulating cooling water pipe group 11 is 1.0 m; and the distance between each circulating cooling water pipe group 11 and the boundary of the concrete structure is not less than 0.5 m. The cooling water pipe arrangement mode that this embodiment adopted can effectively avoid the inhomogeneous drawback of the vertical cooling of bulky concrete structure, reaches the purpose that reduces the vertical temperature gradient of bulky concrete structure, changes vertical cooling temperature field asymmetry.
It should be noted that the above embodiment is only an example in which one cooling water pipe 111 is provided in one horizontal layer, and those skilled in the art may provide a plurality of cooling water pipes 111 in the same horizontal layer according to the technical content and the actual construction requirement, and the present invention is not limited thereto.
Referring to fig. 2 to 3, the present embodiment is described by taking a cable tower bearing platform of a certain bridge in China as an example.
Fig. 2 is a schematic view showing the shape of the cable tower platform formwork, which is a mass concrete structure having a height of 5 m. Fig. 3 is a layout diagram of cooling water pipes in the formwork of the cable tower bearing platform, 5 layers of circulating cooling water pipe groups 11 are pre-arranged in the bearing platform before concrete pouring, each layer of circulating cooling water pipe group 11 comprises 3 or 4 cooling water pipes 111, steel pipes with the pipe diameters of 40 × 2.5mm are adopted, the horizontal distance between every two cooling water pipes 111 is 1.0m, the vertical distance between every two adjacent layers of circulating cooling water pipe groups 11 is 1.0m, and the arrangement directions are mutually perpendicular.
It should be noted that, the concrete pouring of the bearing platform adopts a layered pouring method, specifically, the pouring thickness of each layer is not more than 30cm, and the purpose of layering is to increase the surface coefficient of the concrete so as to be beneficial to the internal heat dissipation of the concrete. In order to ensure the temperature control of each layer of concrete, a water pump set 12 is separately arranged on each layer of circulating cooling water pipe set 11, and the central controller 30 respectively controls each water pump set 12 to circulate water to the circulating cooling water pipe set 11 of the corresponding layer.
According to the circulating cooling system for the mass concrete structure in the water body, provided by the embodiment of the invention, natural water resources around the mass concrete construction of the hydraulic engineering are utilized, and the water resources are regulated, stored, conveyed and distributed, so that the water circulation cooling in the mass concrete is realized, the utilization rate of the water resources is improved, the investment of water supply equipment is reduced, the quality and the efficiency of the engineering construction are ensured, and the civilized construction requirements of energy conservation and environmental protection are met.
The cooling control method for a mass concrete structure in a water body provided by the present application is described below by way of examples.
Example two
Referring to fig. 4, fig. 4 is a schematic flow chart of a cooling control method for a mass concrete structure in a water body according to a second embodiment, where the cooling control method uses a central controller as an execution main body, and includes the following steps:
and step S11, when concrete is poured, after the concrete covers the pre-buried cooling water pipe, water in the water body and the water stored in the cofferdam area are respectively and sequentially extracted to be used as circulating cooling water to carry out circulating water communication on the cooling water pipe, and the water flow rate is regulated according to the temperature of each temperature measuring point acquired in real time, so that the difference between the inlet water temperature and the outlet water temperature of the cooling water pipe is within a preset temperature difference range.
During concrete implementation, the concrete mold-entering temperature needs to be controlled in the concrete pouring construction process, and the mold-entering temperature is not higher than 30 ℃. The concrete pouring adopts a layered pouring method, which specifically comprises the following steps: and pouring thickness of each layer is not more than 30cm, vibrating by using an 80-type vibrating spear after the concrete distribution of each layer is finished, and controlling the vibrating distance according to 50-60 cm. The upper concrete pouring is completed before the initial setting of the lower concrete or on the basis that the concrete poured in the previous time can be remolded, and the initial setting time of the common concrete is 2-3 hours.
Preferably, when the concrete is poured, after the concrete covers the pre-buried cooling water pipe, the step of sequentially extracting the water in the water body and the water stored in the cofferdam area as circulating cooling water to circulate the water through the cooling water pipe includes:
s111, after the pre-buried cooling water pipe is covered by concrete, extracting water in the water body to circulate the cooling water pipe, and storing water in the cofferdam area;
specifically, the water body is a natural water body in which the large-volume concrete structure is located, such as a river, a reservoir, a lake, and the like.
In the concrete pouring process, water is slowly introduced immediately after the concrete covers the cooling water pipe to prevent the pipeline from being blocked, and the reservoir in the cofferdam area does not store water at the moment, so that the central controller controls the double-channel switching device to enable the water inlet of the cooling water pipe to be communicated with the water outlet of the water pump in the water body, the water pump is driven to extract water in the water body to introduce water into the cooling water pipe for cooling, and the water at the water outlet of the cooling water pipe flows back to the water body; after the concrete is initially set, the water flow is increased, the flow speed of cooling water is ensured to be not less than 0.6m/s, the temperature difference between the upper layer concrete and the layer concrete can be reduced, and temperature cracks are prevented; and meanwhile, storing water in the reservoir of the cofferdam area, and performing circulating maintenance by using the stored water after the reservoir is full.
And S112, after the water storage level of the cofferdam area reaches a preset height, extracting the stored water of the cofferdam area as circulating cooling water.
In addition to the influence of the hydration heat of the concrete, the temperature difference between the surface and the inside of the concrete can be caused by the outside air temperature; the sudden drop in outside air temperature increases the gradient of the temperature difference between the surface layer and the interior of the concrete. In order to reduce the internal and external temperature difference as much as possible, after the reservoir is fully stored and before the hydration heat peak value in the concrete appears, the circulating maintenance is carried out by using the stored water, and the temperature difference between the temperature of the cooling water and the internal temperature of the concrete is controlled not to exceed 25 ℃; the method specifically comprises the following steps: central controller control binary channels auto-change over device makes condenser tube's water inlet with the delivery port intercommunication of the water pump in the cistern to it is right to drive water pump extraction retaining condenser tube carries out circulation water-through, will earlier original water in the condenser tube washes outside the cofferdam, makes the circulating water backward flow extremely after washing totally the cistern.
Because the circulating water absorbs the hydration heat of the concrete, the water storage temperature in the water storage tank is continuously increased, and the difference between the water inlet temperature of the cooling water pipe and the internal temperature of the concrete can be reduced, so that the concrete is slowly cooled.
Preferably, after concrete pouring is finished, the concrete surface of the bearing platform can be maintained in a heat preservation mode by means of water storage in the water storage tank, and the difference value between the surface temperature of the concrete and the outside air temperature is controlled, so that the temperature stability of the concrete surface is kept, and the concrete surface is prevented from cracking. The preferable water storage height is 15-20 cm.
Preferably, when the water storage circulating maintenance is utilized, the water storage temperature is adjusted in real time according to the measured concrete surface temperature of the bearing platform, so that the water storage temperature is controlled to be +/-10 ℃ of the concrete surface temperature. On the premise of a certain water storage temperature, the difference between the inlet temperature and the outlet temperature of the cooling water pipe is strictly controlled within a preset temperature difference range by adjusting the flow rate of circulating water, preferably, the preset temperature difference range is 5-10 ℃, the cooling speed of the concrete cannot be ensured to be too fast, and the maximum cooling speed of the concrete cannot be more than 2 ℃/d according to the regulation in the technical Specification for mass concrete construction 3.04.
It should be noted that, in practical application construction, the cooling water pipes pre-embedded in the formwork can be laid in multiple layers, the vertical distance between two adjacent layers of cooling water pipes is 1.0m, and the laying directions are mutually perpendicular; the distance between the parallel pipe bodies of the cooling water pipes on the same horizontal layer is 1.0 m; and the distance between each layer of cooling water pipe and the boundary of the concrete structure is not less than 0.5 m. In order to ensure the temperature control of each layer of concrete, the central controller is used for respectively regulating and controlling the flow rate of circulating water in each layer of cooling water pipe.
And S12, when the internal temperature of the concrete is monitored to reach the preset first temperature threshold value, extracting the water in the water body as circulating cooling water again, and regulating and controlling the water flow rate according to the temperature of each temperature measuring point obtained in real time until the internal temperature of the concrete is lower than the preset second temperature threshold value and the temperature difference value between the internal temperature of the concrete and the surface temperature is lower than 25 ℃.
Specifically, the preset first temperature threshold may be a concrete hydration heat peak value or a certain temperature value close to the concrete hydration heat peak value, and the concrete hydration heat peak value is affected by cement types, cement usage amounts, concrete mold-entering temperature and the like, so the preset first temperature threshold may be set according to actual construction requirements, and is not limited herein.
Preferably, the preset second temperature threshold is 40 ℃.
The temperature of hydration heat in the concrete tends to be stable after reaching the peak value and does not rise any more, and the temperature begins to be reduced gradually (namely, in a cooling period), and in order to enhance the cooling effect, water in the water body is extracted again to be used as circulating cooling water, specifically: the central controller controls the double-channel switching device to enable the water inlet of the cooling water pipe to be communicated with the water outlet of the water pump in the water body, the water pump is driven to extract water in the water body to carry out water cooling on the cooling water pipe, and the water at the water outlet of the cooling water pipe flows back to the water body.
Preferably, if the concrete surface of the platform is filled with water of a certain height for heat preservation and maintenance, the step S12 further includes: the water storage in the bearing platform is reduced until the water storage level is slightly higher than the surface of the concrete, so that the surface of the concrete is ensured to be wet, and meanwhile, the heat dissipation effect of the whole bearing platform is ensured.
In a preferred embodiment, the step S11 further includes: controlling the water in the cooling water pipe to switch the flow direction at a first preset time interval; preferably, the first preset time interval is 12 hours.
Preferably, the step S12 further includes: controlling the water in the cooling water pipe to switch the flow direction at a second preset time interval; preferably, the first preset time interval is 24 hours.
In the above preferred embodiment, by switching the water flow direction in the cooling water pipe at intervals, the phenomenon that the temperature of the inlet side is reduced quickly and the temperature of the outlet side is reduced slowly due to the fact that the circulating cooling water in the same horizontal layer enters the mass concrete structure in a single direction can be effectively avoided, so that the phenomenon that the temperature of the interior of the concrete is reduced unevenly due to the single flow direction of the circulating cooling water in the cooling water pipe is effectively controlled, and the purposes of reducing the horizontal temperature gradient and changing the asymmetry of the horizontal cooling temperature field are achieved.
In another preferred embodiment, the step of regulating the flow rate of the cooling water according to the temperatures at the temperature measurement points acquired in real time includes:
s21, calculating to obtain a temperature change rule of each temperature measuring point based on a pre-established finite element analysis model of the large-volume concrete structure;
s22, calculating the water flow of the cooling water pipe in each time period based on the temperature change rule of each temperature measuring point and by combining the actually measured temperature value;
and S23, controlling the water flow rate in the cooling water pipe according to the water flow.
In the preferred embodiment, the maximum temperature and the temperature gradient at each temperature measurement point are determined by establishing the finite element analysis model of the mass concrete structure, carrying out grid division, carrying out hydrothermal analysis and obtaining the maximum temperature and the temperature distribution rule at each temperature measurement point; according to the heat energy exchange principle, the purpose of effectively controlling the temperature gradient is achieved, the actually measured temperature value of each temperature measuring point is combined, the water flow of the cooling water pipe in each time period is calculated, and the water flow speed in the cooling water pipe is effectively controlled according to the water flow, so that the temperature difference in the large-volume concrete structure is reduced, and the purpose of effectively and uniformly controlling the temperature is achieved.
Preferably, the step S23 includes:
s231, before the internal temperature of the concrete reaches the first temperature threshold value, controlling the water flow through variable speed of a frequency converter to enable the water in the cooling water pipe to be in a turbulent flow state;
and S232, after the internal temperature of the concrete reaches the first temperature threshold value, controlling the water flow through a regulating valve to enable the water in the cooling water pipe to be in a laminar flow state.
In general, turbulence is determined by the reynolds number, as opposed to "laminar flow". The Reynolds number Re is vd/gamma, wherein v is the flow velocity of the cooling water, d is the inner diameter of the cooling water pipe, and gamma is the kinematic viscosity coefficient of the cooling water; the small Reynolds number means that the viscous force among particles is dominant when the cooling water flows, and the particles of the cooling water regularly flow parallel to the inner wall of the pipeline and are in a laminar flow state; the large Reynolds number means that the inertia force is dominant and the cooling water is in a turbulent flow state; generally, the Reynolds number Re of the pipeline is less than 2000 and is in a laminar state, Re is more than 4000 and is in a turbulent state, and Re is 2000-4000 and is in a transitional state. Therefore, when laminar flow flows, cooling water in all layers is not mixed with each other, so that the heat exchange mode is mainly conduction, and turbulent flow is that cooling water particles in all layers are mixed violently, so that the heat exchange is greatly enhanced, the heat release coefficient is higher than that of laminar flow in turbulent flow, and the heat transfer effect of turbulent flow is good.
In order to enhance the heat transfer effect of the circulating cooling water, the frequency converter is used for controlling the water flow in the cooling water pipe in a variable speed manner so as to enable the water in the cooling water pipe to be in a turbulent flow state. However, turbulent flow is formed in the cooling water pipe, so that the heat transfer effect of the cooling water can be enhanced, but the increase of the flow rate can lead to the increase of the water head loss in the pipe, so that the temperature change tends to be stable in the concrete cooling period, the water can be controlled and slowed down through the regulating valve, the flow rate of the cooling water is reduced, the laminar flow is formed in the cooling water pipe to meet the cooling requirement, and the cooling efficiency of the cooling water in the pipe is improved. The flow control adopting the embodiment is very scientific and reasonable.
In summary, the cooling control method and the circulating cooling system for the mass concrete structure in the water body provided by the embodiment of the application utilize natural water resources around the mass concrete construction of the hydraulic engineering, and regulate, store, convey and distribute the water resources, so that the water circulation cooling in the mass concrete is realized, the utilization rate of the water resources is improved, the investment of water supply equipment is reduced, the quality and the efficiency of the engineering construction are ensured, and the civilized construction requirements of energy conservation and environmental protection are met; and the central controller is used for realizing real-time acquisition of temperature information, improving the working efficiency, automatically controlling the cooling water flow of the circulating cooling water pipe system and ensuring the implementation controllability, thereby ensuring the quality of concrete construction.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and may be performed in other orders unless explicitly stated herein. Moreover, at least a portion of the steps in the flow chart of the figure may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
The foregoing is only a partial embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (11)
1. A method for controlling cooling of a bulk concrete structure in a body of water, the method comprising:
when concrete is poured, after the concrete covers the pre-buried cooling water pipe, water in the water body and water stored in the cofferdam area are respectively and successively extracted to be used as circulating cooling water to carry out circulating water communication on the cooling water pipe, and the water flow rate is regulated according to the temperature of each temperature measuring point acquired in real time, so that the difference between the water inlet temperature and the water outlet temperature of the cooling water pipe is within a preset temperature difference range;
when the monitored internal temperature of the concrete reaches a preset first temperature threshold value, water in the water body is extracted again to serve as circulating cooling water, the water flow rate is regulated according to the temperature of each temperature measuring point obtained in real time until the internal temperature of the concrete is lower than a preset second temperature threshold value, and the temperature difference value between the internal temperature of the concrete and the surface temperature is lower than 25 ℃.
2. The method for controlling cooling of a mass concrete structure in a body of water according to claim 1, wherein said circulating water passage of the cooling water pipes by successively extracting water in the body of water and water stored in the cofferdam area after the concrete covers the pre-buried cooling water pipes at the time of concrete pouring comprises:
after the concrete covers the pre-buried cooling water pipe, extracting water in the water body to carry out circulating water communication on the cooling water pipe, and storing water in the cofferdam area;
and after the water storage level of the cofferdam area reaches a preset height, extracting the stored water of the cofferdam area as circulating cooling water.
3. The method of controlling cooling of a bulk concrete structure in a body of water of claim 1, further comprising, before the temperature inside the concrete reaches said first temperature threshold:
and controlling the water in the cooling water pipe to switch the flow direction at a first preset time interval.
4. The method for controlling cooling of a bulk concrete structure in a body of water according to claim 3, wherein said first predetermined time interval is 12 hours.
5. The method of controlling cooling of a bulk concrete structure in a body of water of claim 1, further comprising, after the temperature inside the concrete reaches said first temperature threshold:
and controlling the water in the cooling water pipe to switch the flow direction at a second preset time interval.
6. The method for controlling cooling of a bulk concrete structure in a body of water according to claim 5, wherein said second predetermined time interval is 24 hours.
7. The method for controlling cooling of a mass concrete structure in a body of water according to claim 1, wherein said adjusting the flow rate of cooling water according to the temperatures at the respective temperature measurement points acquired in real time comprises:
calculating to obtain a temperature change rule of each temperature measuring point based on a pre-established finite element analysis model of the large-volume concrete structure;
calculating the water flow of the cooling water pipe in each time period based on the temperature change rule of each temperature measuring point and the actually measured temperature value;
and controlling the water flow speed in the cooling water pipe according to the water flow.
8. The method of controlling cooling of a bulk concrete structure in a body of water according to claim 7, wherein said controlling a water flow rate in said cooling water pipe based on said water flow rate comprises:
before the internal temperature of the concrete reaches the first temperature threshold value, controlling the water flow through variable speed of a frequency converter to enable the water in the cooling water pipe to be in a turbulent flow state;
after the internal temperature of the concrete reaches the first temperature threshold value, the water flow is controlled through the regulating valve, so that the water in the cooling water pipe is in a laminar state.
9. A circulative cooling system of a mass concrete structure in a body of water, comprising: the system comprises a circulating cooling water pipe system, a temperature sensor group and a central controller; the central controller is respectively connected with the circulating cooling water pipe system and the temperature sensor group; wherein,
the temperature sensor group comprises a plurality of temperature sensors arranged in the mass concrete structure and is used for sending real-time temperature information to the central controller;
the central controller is used for controlling the circulating cooling water pipe system to regulate the flow of cooling water according to the real-time temperature information;
the circulating cooling water pipe system comprises at least one circulating cooling water pipe group and at least one water pump group which are horizontally laid in the large-volume concrete structure; each circulating cooling water pipe group comprises at least one cooling water pipe, and the cooling water pipe is a coiled pipe; each water pump group comprises at least two water pumps, the water inlet ends of the two water pumps are respectively communicated with a water body and the cofferdam area through external water pipes, and the water outlet ends of the two water pumps are connected with the water inlets of the cooling water pipes through double-channel switching devices; the double-channel switching device is connected with the central controller and used for controlling the switching and communication between the water inlet of the cooling water pipe and the water outlet ends of the two water pumps according to the switching instruction of the central controller.
10. The circulative cooling system of a bulk concrete structure in a body of water according to claim 9, wherein the circulative cooling water pipe system comprises two or more of the circulative cooling water pipe trains; the vertical distance between two adjacent layers of circulating cooling water pipe groups is 1.0m, and the arrangement directions are mutually vertical; the distance between the parallel pipe bodies of each circulating cooling water pipe group is 1.0 m; and the distance between each circulating cooling water pipe group and the boundary of the concrete structure is not less than 0.5 m.
11. The circulating cooling system for a mass concrete structure in a water body according to claim 9, wherein the water pump is a variable frequency water pump, the circulating cooling water pipe system further comprises at least one frequency converter, each frequency converter is connected with the central controller and the two water pumps, and the frequency converter is used for adjusting the water output of the currently operated water pump according to the control instruction of the central controller.
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Application publication date: 20211221 |