CN116971385A - Temperature control anti-cracking method for mass concrete - Google Patents
Temperature control anti-cracking method for mass concrete Download PDFInfo
- Publication number
- CN116971385A CN116971385A CN202310918121.3A CN202310918121A CN116971385A CN 116971385 A CN116971385 A CN 116971385A CN 202310918121 A CN202310918121 A CN 202310918121A CN 116971385 A CN116971385 A CN 116971385A
- Authority
- CN
- China
- Prior art keywords
- temperature
- concrete
- cooling
- water
- layering
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004567 concrete Substances 0.000 title claims abstract description 175
- 238000000034 method Methods 0.000 title claims abstract description 49
- 238000005336 cracking Methods 0.000 title abstract description 16
- 238000001816 cooling Methods 0.000 claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- 238000012544 monitoring process Methods 0.000 claims abstract description 27
- 238000010276 construction Methods 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 22
- 238000004364 calculation method Methods 0.000 claims abstract description 10
- 238000000465 moulding Methods 0.000 claims abstract description 5
- 239000000498 cooling water Substances 0.000 claims description 20
- 238000005266 casting Methods 0.000 claims description 12
- 238000012360 testing method Methods 0.000 claims description 5
- 238000009413 insulation Methods 0.000 claims description 3
- 230000032798 delamination Effects 0.000 claims 2
- 238000007689 inspection Methods 0.000 abstract description 2
- 238000004458 analytical method Methods 0.000 description 9
- 238000004321 preservation Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 4
- 230000007774 longterm Effects 0.000 description 4
- 238000005457 optimization Methods 0.000 description 4
- 230000000630 rising effect Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000009415 formwork Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 238000011217 control strategy Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 230000002262 irrigation Effects 0.000 description 2
- 238000003973 irrigation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241001330002 Bambuseae Species 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000005094 computer simulation Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- -1 high-rise buildings Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011120 plywood Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000012932 thermodynamic analysis Methods 0.000 description 1
Classifications
-
- 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
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D21/00—Methods or apparatus specially adapted for erecting or assembling bridges
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
- G01K13/10—Thermometers specially adapted for specific purposes for measuring temperature within piled or stacked materials
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K3/00—Thermometers giving results other than momentary value of temperature
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K3/00—Thermometers giving results other than momentary value of temperature
- G01K3/08—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values
- G01K3/14—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values in respect of space
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D2101/00—Material constitution of bridges
- E01D2101/20—Concrete, stone or stone-like material
- E01D2101/24—Concrete
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/08—Thermal analysis or thermal optimisation
Abstract
The invention provides a temperature control anti-cracking method of mass concrete, in the pouring process of concrete, the concrete is poured in layers, the center and the surface of the concrete are controlled by controlling the moulding temperature, the time-varying maximum temperature, the surface temperature and the layering temperature of the concrete, and the differences between the new concrete and the old concrete and between the surface temperature and the air temperature of the concrete are controlled, so that the layering temperature of the concrete is in a gradient range, and the method comprises the following steps: controlling the mold entering temperature of the concrete in a field entering inspection mode; detecting the time-varying maximum temperature of the position of the central axis of the concrete; obtaining the water cooling rate control temperature of the concrete construction site through theoretical calculation of time-varying maximum temperature calibration; by setting monitoring points in the concrete, the layering temperature and the surface temperature of the concrete are monitored, and the layering temperature and the surface temperature are used for detecting the surface and layering stress of the concrete.
Description
Technical Field
The invention relates to the field of bridge construction, in particular to a temperature-control anti-cracking method for mass concrete.
Background
Concrete is used as a product of modern industry and is spread in the life of people, wherein large-scale concrete such as high-rise buildings, water conservancy dams, large bridges and the like often generates cracks, the cracks are generated because the large-scale concrete has large volume, the cement is hardened to release a large amount of heat, the internal temperature of the concrete is too high, the surface heat is easy to dissipate, the temperature difference between the inside and the outside is too large, the compressive stress generated in the concrete and the tensile stress generated on the surface exceed the ultimate tensile strength, and the cracks are generated on the surface; in cold winter, the temperature is too low, and the concrete with saturated water absorption is frozen, so that the expansion force in the concrete is increased, and cracks are caused.
The problem of concrete construction period cracks of a dam or a bridge is a difficult problem which cannot be solved effectively, and the main reason is that besides the influence of complicated construction condition factors in the construction stage, the implementation of a plurality of temperature control measures in the construction process is inevitably interfered by human factors. Many concrete dams with cracks are caused by the fact that the internal temperature cannot be truly cooled or surface protected according to design requirements, so that the stress of the concrete exceeds the standard in the construction period, and the cracks appear. The excessive temperature stress in the construction period is one of the important reasons for cracking the concrete dam, and the temperature problem of the concrete of the arch dam is mainly solved from the two aspects of controlling the temperature and improving the restraint. Three major temperature differences are mainly controlled in the temperature control construction of the prior arch dam: basic temperature difference, internal and external temperature difference and upper and lower layer temperature difference. The basic temperature difference is controlled by the highest temperature, the internal and external temperature differences are controlled by the surface heat preservation and the internal temperature, and the upper and lower layer temperature differences are controlled by the highest temperature of the concrete and the reasonable cooling process. The temperature difference is controlled to reduce the temperature gradient in the concrete pouring process, thereby reducing the temperature stress caused by the temperature gradient.
The current mass concrete temperature control construction follows the guiding ideas of small temperature difference, early cooling and slow cooling, adopts measures such as primary (initial) cooling, middle cooling, secondary (later) cooling and the like to control the temperature of concrete in time, and controls the temperature of space in space through the regional cooling process of a simulated irrigation area, a common cooling area, a transition area and a cover weight area.
However, the temperature control curve model is mainly formulated based on the traditional temperature control strategy of 'three-period nine-stage control drop combination', the setting of the strategy is manually set based on the manual water supply control period, the defects of low standard reaching rate of concrete highest temperature control, discontinuous temperature control process, large temperature gradient, insufficient optimization of temperature control measures and the like are often caused in practical application, and the cracking risk of the concrete is increased.
Disclosure of Invention
Based on the method, the invention provides a temperature control anti-cracking method for mass concrete, which solves the defects of low standard reaching rate of highest temperature control, discontinuous temperature control process, large temperature gradient, insufficient optimization of temperature control measures and the like.
The invention provides a temperature control anti-cracking method of mass concrete, in the pouring process of the concrete, the concrete is poured in layers, and the center and the surface of the concrete are controlled by controlling the moulding temperature, the time-varying maximum temperature, the surface temperature and the layering temperature of the concrete, so that the differences between the new concrete and the old concrete and between the surface temperature and the air temperature of the concrete are controlled, and the layering temperature of the concrete is within a gradient range, and the method comprises the following steps:
controlling the mold entering temperature of the concrete in a field entering test mode;
detecting the time-varying maximum temperature of the position of the central axis of the concrete;
obtaining the water cooling rate control temperature of the concrete construction site through theoretical calculation of the time-varying maximum temperature;
monitoring the layering temperature and the surface temperature of the concrete by setting monitoring points in the concrete, wherein the layering temperature and the surface temperature are used for detecting the surface and layering stress of the concrete.
Further, the monitoring of the concrete layering temperature and the surface temperature by setting monitoring points in the concrete, the layering temperature and the surface temperature being used for detecting the concrete surface and layering stress, comprises:
setting bottom surface measuring points on the bottom template, the top surface or the surface among the concretes, and measuring the temperature field of the bottom template;
surface monitoring points are arranged at the height of 3m from the bottom surface of the concrete and are used for detecting the temperature gradient of Liang Duanmian of the concrete and the outer surface of the web;
and setting check monitoring points at other layers of the concrete pouring process, wherein the check monitoring points are used for detecting the highest temperature inside the concrete and checking the surface temperature.
Further, cooling pipes are arranged on the periphery of the concrete in the process of layered casting of the concrete.
Further, the inlet water temperature of the cooling pipe is monitored and used for controlling the maximum temperature rising value and the maximum temperature reducing rate of the concrete by adjusting the inlet water temperature.
Further, the outlet water temperature of the cooling pipe is monitored and used for adjusting the cooling water input rate or the inlet water temperature through the temperature rise value of the cooling water.
Further, the cooling pipes are arranged on the concrete in layers, and the density of the cooling pipes is set according to 1.3-1.5 m of interval on the horizontal plane and 1.3-1 m of interval on the vertical height direction.
Further, the cooling pipes of each layer are independently supplied with water, and the water supply direction of the cooling water in the cooling pipes of each layer is alternately supplied.
Further, the flow rate of cooling water in the cooling pipe of each layer is not less than 0.65m/s, the flow rate of the water pipe is not less than 22.3L/min, and the cooling water forms a turbulent flow state in the cooling pipe.
Further, the method also comprises the steps of testing the ambient temperature and calculating the ambient temperature difference so as to adjust the heat insulation structure according to the temperature difference.
From the technical scheme, the mass concrete temperature control cracking resistance method provided by the invention has the following beneficial effects:
the method for controlling and cracking the large-volume concrete body is applied to the construction of large-volume medium-low-heat concrete arch dams, can obviously improve the highest temperature control standard reaching rate, ensures that the temperature gradient of space-time dimension meets the design requirement, is dynamically adjustable, reduces the temperature stress and reduces the cracking risk of the dams. The standard reaching rate of the highest temperature is improved by dynamically controlling the pouring process before and after the temperature rising period, the time-space temperature gradient is adjustable by the continuous cooling period, and the opening of the transverse joint and the grouting of the joint are ensured. By long-term monitoring of the concrete temperature after the water is introduced into the structure in the rise period, the continuity of the temperature data in the whole life cycle is ensured, and basic data are accumulated for temperature rise rules and analysis of the long-term performance of the dam concrete.
Drawings
FIG. 1 is a control relationship diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a hierarchical arrangement of monitoring points according to an embodiment of the present invention;
FIG. 3 is a view of the monitoring point arrangement in the horizontal direction of arrangement 1 of FIG. 2 in accordance with an embodiment of the present invention;
FIG. 4 is a view of the monitoring point arrangement in the horizontal direction of arrangement 2 of FIG. 2 in accordance with an embodiment of the present invention;
FIG. 5 is a view of the monitoring point arrangement in the horizontal direction of arrangement 3 of FIG. 2 in accordance with an embodiment of the present invention;
FIG. 6 is a schematic view of a cooling tube of an embodiment of the present invention layered in a vertical direction;
fig. 7 is a horizontal arrangement view of the water pipe 1 of fig. 6 according to an embodiment of the present invention;
fig. 8 is a horizontal arrangement view of the water pipe 2 in fig. 6 according to an embodiment of the present invention;
fig. 9 is a horizontal arrangement view of the water pipe 3 of fig. 6 according to an embodiment of the present invention;
fig. 10 is a horizontal arrangement view of the water pipe 4 in fig. 6 according to an embodiment of the present invention;
FIG. 11 is a diagram of a computational model of heat of hydration of a concrete placement space solid model according to an embodiment of the present invention;
FIG. 12 is a graph showing the internal temperature change of the mold of FIG. 11 according to an embodiment of the present invention.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
The current mass concrete temperature control construction follows the guiding ideas of small temperature difference, early cooling and slow cooling, adopts measures such as primary (initial) cooling, middle cooling, secondary (later) cooling and the like to control the temperature of concrete in time, and controls the temperature of space in space through the regional cooling process of a simulated irrigation area, a common cooling area, a transition area and a cover weight area.
However, the temperature control curve model is mainly formulated based on the traditional temperature control strategy of 'three-period nine-stage control drop combination', the setting of the strategy is manually set based on the manual water supply control period, the defects of low standard reaching rate of concrete highest temperature control, discontinuous temperature control process, large temperature gradient, insufficient optimization of temperature control measures and the like are often caused in practical application, and the cracking risk of the concrete is increased.
In terms of the mechanical mechanism of cracking and the aim of controlling the construction temperature of the mass concrete, the essence of the construction temperature control of the mass concrete is temperature control and stress control, and the concrete is as follows: the tensile strength of the concrete structure with a large volume, which is controlled not to exceed the tensile strength of the concrete in the corresponding age, can generate two types of cracks under the common influences of internal factors (temperature shrinkage, hydration shrinkage, elastic modulus increase and tensile strength increase), external environment conditions (temperature change, wind speed and humidity), basic constraint conditions and construction process: surface and deep cracks and through cracks. In order to ensure the construction quality of the large-volume concrete structure, temperature prediction must be accurately performed according to the actual conditions of engineering, temperature stress analysis must be performed in detail, and a temperature control scheme can be reasonably formulated to avoid and prevent cracks.
As shown in fig. 1, the present invention provides a temperature-controlled crack-resistant method for mass concrete, in which concrete is layered in a casting process, and differences between a center and a surface of concrete, between new concrete and old concrete, and between a surface temperature and an air temperature of concrete are controlled by controlling a mold-in temperature, a time-varying maximum temperature, a surface temperature, and a layering temperature of concrete, so that the layering temperature of concrete is within a gradient range, comprising:
controlling the mold entering temperature of the concrete in a field entering inspection mode;
detecting the time-varying maximum temperature of the position of the central axis of the concrete;
obtaining the water cooling rate control temperature of the concrete construction site through theoretical calculation of time-varying maximum temperature calibration;
by setting monitoring points in the concrete, the layering temperature and the surface temperature of the concrete are monitored, and the layering temperature and the surface temperature are used for detecting the surface and layering stress of the concrete.
The method for controlling and cracking the large-volume concrete body is applied to the construction of large-volume medium-low-heat concrete arch dams, can obviously improve the highest temperature control standard reaching rate, ensures that the temperature gradient of space-time dimension meets the design requirement, is dynamically adjustable, reduces the temperature stress and reduces the cracking risk of the dams. The standard reaching rate of the highest temperature is improved by dynamically controlling the pouring process before and after the temperature rising period, the time-space temperature gradient is adjustable by the continuous cooling period, and the opening of the transverse joint and the grouting of the joint are ensured. By long-term monitoring of the concrete temperature after the water is introduced into the structure in the rise period, the continuity of the temperature data in the whole life cycle is ensured, and basic data are accumulated for temperature rise rules and analysis of the long-term performance of the dam concrete.
Furthermore, the method is used for controlling the casting temperature in the concrete casting process by controlling the casting temperature of the concrete, reducing the temperature rise of the concrete, delaying the appearance time of the highest temperature, controlling the cooling rate of the concrete after the temperature peak, reducing the temperature difference between the center and the surface of the concrete and between the temperature of new and old concrete and controlling the difference between the surface temperature and the temperature of the concrete.
Further, specific data of the temperature also needs to be determined according to specific conditions such as air temperature, concrete mixing ratio, structural size, constraint condition and the like.
Further, as shown in fig. 2, by setting monitoring points in the concrete, the layering temperature and the surface temperature of the concrete are monitored, and the layering temperature and the surface temperature are used for detecting the surface and the layering stress of the concrete, comprising:
a bottom surface measuring point is provided on the bottom formwork, the top surface of the concrete or the surface between the concrete for measuring the temperature field of the bottom formwork for accurately analyzing the heat dissipation situation of the bottom formwork, as in the arrangement 1 of fig. 2.
Further, to capture the temperature gradient of the top surface of the concrete poured in the first and second layers, a sensor may be also placed 3-10cm from the surface, as shown in fig. 3.
Further, the measuring point on the bottom surface is 3-10cm, preferably 5 cm, from the bottom surface.
Further, surface monitoring points are provided at a height of 3m from the concrete floor for detecting the temperature gradient of Liang Duanmian of the concrete and the outer surface of the web, as in arrangement 2 in fig. 2, and its arrangement position on the horizontal plane as in fig. 4.
Further, check monitoring points are arranged on other layers of the concrete pouring process and used for detecting the highest temperature inside the concrete and checking the surface temperature, as shown in the arrangement 3 in fig. 2, and the arrangement position of the check monitoring points on the horizontal plane is shown in fig. 4.
Further, in order to ensure the effectiveness of the monitoring points, a plurality of standby measuring points with the same arrangement mode are added in the concrete pouring process.
Further, as shown in fig. 6 to 10, cooling pipes are provided around the concrete during the layered casting of the concrete.
Wherein the distribution of the cooling pipes in the vertical direction is shown in fig. 6, and the distribution pattern of the cooling pipes of each level in the horizontal direction is shown in fig. 7 to 10, and the specific distribution pattern is determined according to the shape and properties of the concrete and the temperature control manner.
The maximum limit of the highest temperature is considered in the arrangement and optimization of the tube cooling scheme, and the tube cooling measure has the maximum effect on cooling after the concrete is poured, so that the tube cooling measure is fully considered to reduce the highest temperature.
Further, the cooling distance of the tube from the top surface, the bottom surface and the side surfaces is controlled according to 1.5m and 1.4m
Further, the first layer of poured concrete is provided with 5 layers of cooling pipes altogether, and the second layer of poured concrete is provided with 1 layer of cooling pipes altogether.
Further, the cooling distance of the tube from the top surface, the bottom surface and the side surfaces was controlled to 1.5m and 1.4 m.
The cooling water pipe is made of iron pipes with diameter of 32 mm and 2 mm. The water pipe joints are tightly connected according to the attached parts
The pipe cold layout is used for pipe cold positioning construction, and necessary steel bars are added in the construction to position or support the water pipe.
Further, the inlet water temperature of the cooling pipe is monitored and used for controlling the maximum temperature rise and the maximum temperature drop rate of the concrete by adjusting the inlet water temperature.
Further, the outlet water temperature of the cooling pipe is monitored and used for adjusting the cooling water input rate or the inlet water temperature through the temperature rise value of the cooling water.
Further, the cooling pipes are layered on the concrete, and the density of the cooling pipes is set at intervals of 1m on the horizontal plane and 1.3-1.5 m in the vertical height direction.
Further, the cooling pipes of each layer are independently supplied with water, and the water supply direction of the cooling water in the cooling pipes of each layer is alternately supplied.
Further, the flow rate of cooling water in the cooling pipes of each layer is not less than 0.65m/s, the flow rate of the water pipes is not less than 22.3L/min, and the cooling water forms a turbulent flow state in the cooling pipes.
Furthermore, each layer of circulating cooling water pipe starts to be filled with water at the latest when the circulating cooling water pipe is covered by concrete, and the water filling time and the water filling amount are determined according to the temperature control and temperature measurement result.
Furthermore, the maximum water flow is required to be communicated before the concrete is poured to the temperature peak, so that the temperature peak of the concrete is reduced as much as possible; after the temperature peak, the water flow is adjusted according to the cooling rate, so that concrete cracking caused by too fast cooling is prevented.
Furthermore, after the upper concrete layer is poured, a layer of cooling water pipe on the top surface of the lower concrete layer is required to be subjected to secondary water supply.
Furthermore, when the maximum temperature in the concrete is within 15 ℃ from the average temperature in the recent 3 days, water supply can be stopped.
Further, the method also comprises the steps of testing the ambient temperature and calculating the ambient temperature difference so as to adjust the heat preservation structure according to the temperature difference.
Further, the temperature of the environmental system is measured, including the air temperature, the inlet and outlet water temperature of the cooling water pipe, the concrete pouring temperature and the like.
Further, the method also comprises the temperature control of concrete pouring, and the control of the concrete pouring temperature is very important to control concrete cracks. The temperature rise of the same concrete at the high molding temperature is much larger than that at the low molding temperature. The pouring temperature is mainly influenced by the temperature of raw materials, the air temperature and the like. The casting temperature can be estimated by measuring the temperature of cement, fly ash, mineral powder, sand, stone, water, taking into account the ambient temperature, before the concrete is cast. Because the temperature of sand, stone and water is influenced by the air temperature, the concrete pouring temperature mainly depends on the environment temperature under the condition that the temperature of the rubber material is fixed, and therefore, it is important to select proper time for concrete pouring.
If the casting temperature exceeds the highest temperature control requirement, adopting phase measures to reduce the casting temperature through thermal calculation and reducing the temperature of each raw material so as to enable the casting temperature to meet the control standard.
Further, the temperature rise in the concrete pouring process is calculated according to the formula, and the concrete heat insulation temperature rise calculation formula is as follows:
T＝cQm
wherein:
q is heat;
c-specific heat capacity of concrete, 0.96 kJ/(kg. DEG C);
m-concrete mass, 2600kg/m3.
Furthermore, in the invention, the Ansys finite element software is used for calculating to establish a space entity model, thermodynamic analysis is carried out, and the cooling effect of the tube is considered. The model is shown in fig. 11, the water pipe model distributed around the model is also shown in fig. 11, the structural symmetry is considered, a 1/4 model is selected for analysis, the entity model comprises a layer of concrete and a layer of concrete, solid units are built by Solid70 units in calculation, a water pipe is built by Link34 units, water cooling is considered as the average temperature of the environment (both 22 ℃), the mold entering temperatures of the two layers of concrete are considered according to 22 ℃, the bottom surface and the side surface are made of bamboo plywood, the heat dissipation is 3W/m < 2 >, the top surface and the end surface are covered and insulated, and the calculation is carried out according to 4W/m < 2 >. The first and second casting is considered at a distance of 7 d.
The water cooling flow rate is considered according to 0.65m/s, and the water cooling convection heat exchange coefficient is calculated according to the following calculation formula:
h water ＝(552.4v+50.0)W/(m 2 ·K)＝409W/(m 2 ·K)
in the temperature analysis, the surface heat dissipation is constant under the condition of considering the package and heat preservation, and the surface and the outside heat dissipation are equivalently considered at the average air temperature of 22 ℃ in the analysis.
Considering the influence of creep on the concrete stress during stress calculation, the creep value of the concrete is shown as the following formula according to an empirical numerical model:
C(t,τ)＝c 1 (1+9.20τ -0.45 )(1-l -0.30(t-τ) )+c 2 (1+1.70τ -0.45 )(1-l -0.005(t-τ) )
wherein: c1 =0.23/E2, c2=0.52/E2, E2 being the final elastic modulus.
Through modeling analysis, the temperature gradient exists near the pipe cold and on the surface, and the temperature rising and falling process is generally gentle. The change in the maximum temperature of the first layer was extracted, the maximum temperature of the first layer was 74.9 c,
the relative temperature rise was 52.9 ℃, the highest temperature of the second layer was 73.2 ℃, and the relative temperature rise was 51.2 ℃. The highest temperature is not higher than 75 ℃, and the calculated temperature meets the control requirement.
According to the analysis in the 1/4 model in FIG. 11, the results obtained by modeling analysis are shown in FIG. 12, and the temperature gradient exists near the pipe cold and on the surface, and the temperature rise and fall process is generally gentle. The maximum temperature of the first layer was 74.9℃and the relative temperature rise was 52.9℃while the maximum temperature of the second layer was 73.2℃and the relative temperature rise was 51.2 ℃. The highest temperature is not higher than 75 ℃, and the calculated temperature meets the control requirement.
Because the structure is subjected to a smaller external constraint effect, the main temperature stress is caused by uneven temperature distribution;
the surface temperature and the temperature around the pipe cold are lower in the early stage, so that the tensile stress is expressed, and the temperature stress gradually decreases along with the gradual decrease of the temperature in the later stage. The maximum stress parts of the structure are corner boundary areas, the areas are cooled faster, the temperature stress is relatively high, and local heat preservation and moisture preservation maintenance are enhanced.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the invention thereto, but to limit the invention thereto, and any modifications, equivalents, improvements and equivalents thereof may be made without departing from the spirit and principles of the invention.
Claims (9)
1. The method is characterized in that in the pouring process of the concrete, the concrete is poured in layers, and the differences between the center and the surface of the concrete, between new concrete and old concrete and between the surface temperature and the air temperature of the concrete are controlled by controlling the molding temperature, the time-varying maximum temperature, the surface temperature and the layering temperature of the concrete, so that the layering temperature of the concrete is in a gradient range, and the method comprises the following steps:
controlling the mold entering temperature of the concrete in a field entering test mode;
detecting the time-varying maximum temperature of the position of the central axis of the concrete;
obtaining the water cooling rate control temperature of the concrete construction site through theoretical calculation of the time-varying maximum temperature;
monitoring the layering temperature and the surface temperature of the concrete by setting monitoring points in the concrete, wherein the layering temperature and the surface temperature are used for detecting the surface and layering stress of the concrete.
2. The method of claim 1, wherein the monitoring of the concrete's delamination temperature and surface temperature for detecting the concrete surface and delamination stress by setting monitoring points within the concrete comprises:
setting bottom surface measuring points on the bottom template, the top surface or the surface among the concretes, and measuring the temperature field of the bottom template;
surface monitoring points are arranged at the height of 3m from the bottom surface of the concrete and are used for detecting the temperature gradient of Liang Duanmian of the concrete and the outer surface of the web;
and setting check monitoring points at other layers of the concrete pouring process, wherein the check monitoring points are used for detecting the highest temperature inside the concrete and checking the surface temperature.
3. The method of claim 1, wherein cooling pipes are provided around the periphery of the concrete during the layered casting of the concrete.
4. A method according to claim 3, wherein the inlet water temperature of the cooling pipe is monitored for controlling the maximum temperature rise and rate of cooling of the concrete by adjusting the inlet water temperature.
5. A method according to claim 3, characterized in that the outlet water temperature of the cooling pipe is monitored for adjusting the cooling water input rate or the inlet water temperature by means of the temperature rise value of the cooling water.
6. The method according to claim 1, wherein the cooling pipes are layered on the concrete, and the density of the cooling pipes is set at intervals of 1m in a horizontal plane and 1.3 to 1.5m in a vertical height direction.
7. The method of claim 1, wherein the cooling pipes of each layer are supplied with water independently, and the direction of supply of the cooling water in the cooling pipes of each layer is alternately supplied.
8. The method of claim 1, wherein a flow rate of cooling water in the cooling tube of each layer is not less than 0.65m/s, a water tube flow rate is not less than 22.3L/min, and the cooling water forms a turbulent state in the cooling tube.
9. The method of claim 1, further comprising testing an ambient temperature and calculating an ambient temperature differential to adjust the insulation structure based on the temperature differential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310918121.3A CN116971385A (en) | 2023-07-25 | 2023-07-25 | Temperature control anti-cracking method for mass concrete |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310918121.3A CN116971385A (en) | 2023-07-25 | 2023-07-25 | Temperature control anti-cracking method for mass concrete |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116971385A true CN116971385A (en) | 2023-10-31 |
Family
ID=88478998
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310918121.3A Pending CN116971385A (en) | 2023-07-25 | 2023-07-25 | Temperature control anti-cracking method for mass concrete |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116971385A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117232671A (en) * | 2023-11-13 | 2023-12-15 | 江苏莱士敦建筑科技有限公司 | Temperature measurement method and system for mass concrete temperature field |
-
2023
- 2023-07-25 CN CN202310918121.3A patent/CN116971385A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117232671A (en) * | 2023-11-13 | 2023-12-15 | 江苏莱士敦建筑科技有限公司 | Temperature measurement method and system for mass concrete temperature field |
| CN117232671B (en) * | 2023-11-13 | 2024-01-30 | 江苏莱士敦建筑科技有限公司 | Temperature measurement method and system for mass concrete temperature field |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108133111A (en) | A kind of Study on Temperature Field method and temprature control method based on mass concrete | |
| CN105544578B (en) | A kind of method for determining large volume concrete structural construction and maintenance method | |
| CN101781931B (en) | Construction method of large-volume concrete bearing platform with one-time pouring in winter | |
| CN103293179B (en) | The early stage thermal expansion coefficient testing device of concrete based on suspension method and method of testing | |
| CN116971385A (en) | Temperature control anti-cracking method for mass concrete | |
| CN107816044B (en) | A kind of dumbbell shape structure Concreting of Large Volume Bearing Platform method for controlling crack | |
| CN112726421B (en) | Construction process of bridge pier bearing platform | |
| Yu et al. | Research on the influence factors of thermal cracking in mass concrete by model experiments | |
| CN116680782A (en) | Large-volume concrete construction temperature control method based on temperature rise regulation and control | |
| CN103257153A (en) | Method for monitoring stress change state of compensating concrete expansion reinforcing band | |
| Zhang et al. | Analysis of factors influencing the temperature field variation in mass concrete during hydration heat release | |
| Cai et al. | Early hydration heat temperature field of precast concrete T-beam under steam curing: Experiment and simulation | |
| CN116674052A (en) | Concrete anti-cracking control method for ballastless track slab | |
| Su et al. | Development and performance test including mechanical and thermal of new tenon composite block masonry walls | |
| Groth et al. | Air cooling of concrete by means of embedded cooling pipes—Part II: Application in design | |
| CN207553608U (en) | Mass concrete controls the structure of thermal cracking | |
| CN103104097B (en) | Ultra-long concrete base arrangement cancels the recursion cross construction method of temperature post-cast strip | |
| Xue et al. | Stress development and crack monitoring of massive concrete walls with embedded air-cooling pipes | |
| Sun et al. | Temperature Control for Mass Concrete Construction of Wentang Bridge 5# Pier Pile Cap in Winter Construction | |
| Siang | Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate | |
| Xie et al. | Influence of the different pipe cooling scheme on temperature distribution in RCC arch dams | |
| Geng et al. | Experimental and theoretical internal forced convection investigation on air pipe cooling of large-dimension RC walls | |
| CN110130282B (en) | Temperature control anti-cracking method for flood discharge tunnel lining concrete construction period | |
| Wu et al. | Temperature Control for Mass Concrete of Bridge Cap in Summer Construction | |
| CN203429563U (en) | Pier bottom mass concrete temperature regulating device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |