CN111914322B - Method for determining differential mixing proportion of structural concrete of subway station - Google Patents
Method for determining differential mixing proportion of structural concrete of subway station Download PDFInfo
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- 238000002156 mixing Methods 0.000 title claims abstract description 98
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000005336 cracking Methods 0.000 claims abstract description 41
- 230000005484 gravity Effects 0.000 claims abstract description 6
- 238000012937 correction Methods 0.000 claims abstract description 4
- 239000000843 powder Substances 0.000 claims description 39
- 239000002893 slag Substances 0.000 claims description 39
- 239000000203 mixture Substances 0.000 claims description 26
- 238000005266 casting Methods 0.000 claims description 15
- 238000010276 construction Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 13
- 230000036571 hydration Effects 0.000 claims description 11
- 238000006703 hydration reaction Methods 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 9
- 238000012423 maintenance Methods 0.000 claims description 8
- 239000011398 Portland cement Substances 0.000 claims 1
- 230000003487 anti-permeability effect Effects 0.000 claims 1
- 239000004568 cement Substances 0.000 description 34
- 239000010881 fly ash Substances 0.000 description 27
- 239000004576 sand Substances 0.000 description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 239000000654 additive Substances 0.000 description 18
- 230000000996 additive effect Effects 0.000 description 18
- 239000004575 stone Substances 0.000 description 10
- 230000008859 change Effects 0.000 description 9
- 230000009467 reduction Effects 0.000 description 4
- 230000000740 bleeding effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003469 silicate cement Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000009415 formwork Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
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- G—PHYSICS
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- 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
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/2038—Resistance against physical degradation
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/27—Water resistance, i.e. waterproof or water-repellent materials
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
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Abstract
The invention discloses a method for determining a differential mixing ratio of concrete of a subway station structure, which is used for calculating and analyzing the temperature stress and the shrinkage stress of a concrete pouring body according to the structural characteristics of the concrete pouring body to obtain the influence factors of the temperature stress and the shrinkage stress of the concrete pouring body, and changing the mixing ratio of the concrete according to the influence factors. According to the invention, the main body structure of underground engineering such as subways is subdivided into different structural parts, the specific gravity of each structural part, which is influenced by temperature stress and shrinkage stress to cause cracking, is analyzed and calculated to obtain the temperature stress influence factor and the shrinkage stress influence factor respectively, and the existing concrete mixing proportion is subjected to differential correction according to the specific gravity of the temperature stress influence factor and the shrinkage stress influence factor, so that the strength index, the impervious index and the cracking index of the concrete are balanced, and the cracking requirements of the concrete with different structures are met.
Description
Technical Field
The invention relates to the technical field of engineering construction, in particular to a method for determining a concrete differentiated mixing ratio of a subway station structure.
Background
The subway engineering is an important municipal traffic engineering of modern cities, and urban residents carrying large passenger flows have great weight, and the engineering quality is a century old.
In water-rich areas, particularly in Shenzhen coastal cities, groundwater has a corrosion effect on concrete, the safety and durability of the structure are directly affected, horizontal or vertical harmful cracks are generated, and the quality of underground engineering such as subways is further affected by the existence of the harmful cracks. Even though the construction inspection and acceptance can be realized in delivery, structural leakage still repeatedly occurs in an operation stage, particularly after the water level reaches the designed water level elevation, a construction unit needs to pay huge plugging cost, the unit price is more than several times of that in the construction stage, great economic burden is caused for a construction general package unit, the engineering benefit is reduced, and meanwhile, the social negative influence is caused, so that the safety and convenience of passengers are threatened.
The concrete main body structure is easy to generate horizontal cracks, vertical cracks and other harmful cracks under the action of temperature stress and shrinkage stress generated by annual temperature difference and concrete drying shrinkage, and particularly, the temperature stress and the shrinkage stress are larger in early concrete pouring, the change is quicker, and the influence on a concrete pouring body is larger. In the prior art, the proportion of the concrete only considers the strength and permeability indexes, and the crack resistance of the ready-mixed concrete is not considered, so that the concrete cracks under the combined action of temperature stress and shrinkage stress at early stage, and the underground engineering water leakage condition is serious.
The above disadvantages are to be improved.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for determining the concrete differential mixing ratio of a subway station structure.
The technical scheme of the invention is as follows:
According to structural characteristics of a concrete casting body, temperature stress and shrinkage stress of the concrete casting body are calculated and analyzed, influence factors of the temperature stress and the shrinkage stress of the concrete casting body are determined, and the concrete mixing ratio is changed according to the influence factors.
According to the method for determining the differential mixing proportion of the subway station structure concrete, the standard mixing proportion of the concrete is determined according to the environment, the construction process, the mixing proportion of the concrete and the maintenance condition, and when the temperature stress influence factor of the concrete pouring body is larger than the shrinkage stress influence factor, the silicate cement consumption is reduced from the standard mixing proportion of the concrete.
According to the method for determining the differential mixing proportion of the subway station structure concrete, the standard concrete mixing proportion is determined according to the environment, the construction process, the concrete mixing proportion and the maintenance condition, and when the shrinkage stress influence factor of the concrete pouring body is larger than the temperature stress influence factor, the slag powder mixing amount is reduced from the standard concrete mixing proportion.
According to the method for determining the differential mixing proportion of the subway station structure concrete, the temperature stress influence factor of the bottom plate is smaller than the shrinkage stress influence factor.
Further, the temperature stress influence factor of the base plate was 0.48, and the shrinkage stress influence factor was 0.52.
Still further, in the concrete cementing material of the bottom plate, the proportion of the ground slag powder is not more than 15.00%.
According to the method for determining the differential mixing proportion of the subway station structure concrete, the temperature stress influence factor of the side wall is smaller than the shrinkage stress influence factor.
Further, the temperature stress influence factor of the side wall is 0.35, and the influence factor of the shrinkage stress is 0.65.
Still further, in the concrete cementing material of the side wall, the proportion of the ground slag powder is not more than 10.00%.
According to the method for determining the differential mixing proportion of the subway station structure concrete, the shrinkage stress influence factors of the top plate and the middle plate are larger than the temperature stress influence factors.
Further, the shrinkage stress influence factor of the top plate and the middle plate is 0.51, and the influence factor of the temperature stress is 0.49.
Still further, the ground slag powder accounts for no more than 16.00% of the concrete cementing material of the top plate and the middle plate.
According to the method for determining the concrete differentiated mixing ratio of the subway station structure, the concrete mixing ratio of the bottom plate is as follows: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 20.00-25.00%, the mixing amount of the slag powder is 10.00-15.00%, and the mixing amount of the additive is 1.50-2.00%.
According to the method for determining the concrete differentiated mixing proportion of the subway station structure, the concrete mixing proportion of the side wall is as follows: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 25.00-30.00%, the mixing amount of the slag powder is 0.00%, and the mixing amount of the additive is 1.50-2.00%.
According to the method for determining the concrete differentiated mixing ratio of the subway station structure, the concrete mixing ratio of the top plate and the middle plate is as follows: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 20.00-25.00%, the mixing amount of the slag powder is 10.00%, and the mixing amount of the additive is 1.50-2.00%.
According to the scheme, the underground engineering main structure of the subway and the like is subdivided into different structural parts, the proportion of cracking caused by the influence of temperature stress and shrinkage stress of each structural part is analyzed and calculated, the temperature stress influence factor and the shrinkage stress influence factor are obtained respectively, the existing concrete mixing proportion is subjected to differential correction according to the proportion of the temperature stress influence factor and the shrinkage stress influence factor, and the strength index, the impervious index and the cracking resistance index of the concrete are balanced so as to meet the cracking resistance requirements of the concrete with different structures.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of the structure of a base plate of a conventional standard station of a subway.
Fig. 2 is a schematic diagram of a side wall structure of a conventional standard station of a subway.
Fig. 3 is a schematic diagram of a roof structure of a conventional standard station of a subway.
Wherein, each reference sign in the figure:
1. a bottom plate; 2. a side wall; 21. a construction joint; 3. axillary angle; 4. an underground enclosure; 5. and a top plate.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
According to the structural characteristics of the concrete casting body, the temperature stress and the shrinkage stress of the concrete casting body are calculated and analyzed to obtain the influence factors of the temperature stress and the shrinkage stress of the concrete casting body, and the concrete mixing ratio is changed according to the influence factors.
According to the invention, the main body structure of underground engineering such as subways is subdivided into different structural parts, the specific gravity of each structural part, which is influenced by temperature stress and shrinkage stress to cause cracking, is analyzed and calculated to obtain the temperature stress influence factor and the shrinkage stress influence factor respectively, and the existing concrete mixing proportion is subjected to differential correction according to the specific gravity of the temperature stress influence factor and the shrinkage stress influence factor, so that the strength index, the impervious index and the cracking index of the concrete are balanced, and the cracking requirements of the concrete with different structures are met.
Within 14 days after the concrete casting body is cast, the temperature change is generated due to the hydration heat of the concrete, and as the time change, the temperature difference and the temperature reduction of each part of the concrete casting body are caused due to the property and the structure of the concrete, so that the temperature difference stress is formed, and the shrinkage stress of the concrete is influenced by the temperature difference stress. Meanwhile, as the concrete automatically contracts due to the change of the water content, shrinkage stress is generated, the shrinkage stress can be gradually released according to the growth of the concrete pouring body, and in the initial growth period of the concrete pouring body, especially in 2-7 days after the concrete pouring body is poured, the shrinkage stress of approximately 80% is released, the change rate of the water content in the concrete pouring body is larger, the volume change speed is higher, the shrinkage rate of the concrete is high, and the shrinkage stress is large. Therefore, in the early forming process of the concrete pouring body, temperature stress and shrinkage stress are important influencing factors influencing the cracking of the concrete, and when the cracking resistance of the concrete is considered, the cracking resistance index of the concrete needs to be established on the basis, which is a basic principle of designing the mixing proportion of the cracking resistant concrete:
(1) Low shrinkage: the shrinkage of the concrete directly represents the shrinkage stress of the concrete, and the concrete with low strength and low shrinkage is a basic requirement for reducing cracking when the early concrete is not cured and formed;
(2) Low cracking properties: the cracking performance shows the dry shrinkage condition of the concrete, and the structural concrete configuration requirement of the subway station needs to have early-stage low cracking performance;
(3) Low bleeding: the high bleeding rate can cause poor compaction performance after concrete pouring and tamping, less aggregate, more slurry, more water content, large water change rate, large shrinkage stress and shrinkage cracking, so the low bleeding rate is the early low cracking performance required by the structural concrete of the subway station;
(4) High workability: at low water-to-gel ratios, good workability means good workability, especially pumping performance.
The main body structure of subway station and interval is subdivided and divided into different structural parts, the structural characteristics of the conventional standard station are analyzed, the concrete main body structure comprises a bottom plate 1, a side wall 2, a top plate 5 and a middle plate, the thickness ratio of the concrete main body structure is about 1:0.9:0.96:0.96, and the main factors influencing concrete cracking are different due to the difference of the concrete structures.
Because the temperature of each part of the concrete casting body is different due to the temperature change of the hydration heat of the concrete, the structural temperature difference and the temperature reduction are formed, and therefore the temperature stress is generated. Therefore, the temperature stress is influenced by the temperature of the inner surface of the concrete and the cooling rate, and when the conditions of the same environment, construction process, concrete mixing ratio, maintenance condition and the like are consistent, the temperature stress is directly related to the highest temperature rise caused by the hydration heat of the concrete. Meanwhile, the thickness of the concrete casting body influences temperature transmission, and is one of reasons for causing the temperature difference and the cooling rate of the interior surface. In summary, the thermal insulation temperature rise and the thickness of the concrete casting body affect the temperature stress.
The self-shrinkage caused by the change of the water content of the concrete generates shrinkage stress, the shrinkage stress causes the deformation of the concrete pouring body, and the deformation of the concrete pouring body is subjected to external constraint, so that the shrinkage stress is directly related to the constraint condition of the structure when the conditions of the same environment, construction process, concrete mixing ratio, maintenance condition and the like are consistent.
And analyzing the bottom plate 1, the side walls 2, the top plate 5 and the middle plate one by one according to the influence factors of the temperature stress and the shrinkage stress.
(1) Bottom plate 1
From the temperature stress analysis, the thickness of the bottom plate 1 is relatively thicker, only the surface of the bottom plate is subjected to single-sided heat dissipation, the highest temperature rise caused by the hydration heat of the concrete is larger, and the temperature difference of the structural part is larger, so that the influence of the temperature stress on the cracking performance of the bottom plate 1 is larger.
From the analysis of shrinkage stress angle, the subway station is deeply buried with the section, and the foundation condition is good, which means that the external constraint stress of the bottom plate 1 is large, as shown in fig. 1, the bottom plate 1 is limited by the plane of the base surface and is also limited by the vertical of the side wall of the underground enclosing structure 4, especially the axillary angle 3, at the joint of the bottom plate 1 and the side wall 2, so that the cracking is more easy to generate. Therefore, the shrinkage stress has a large influence on the concrete cracking performance of the floor panel 1.
In view of the above, the concrete mix ratio of the base plate 1 needs to comprehensively consider the dual factors of the temperature stress and the shrinkage stress.
In early stage of concrete growth, the concrete is not affected by annual temperature difference, the biggest influencing factor of temperature stress is hydration heat release, and the concrete casting body can release shrinkage stress of approximately 80% of the structure in early stage 2-7 days. Therefore, in early stages of concrete growth, shrinkage stress should have a slightly greater effect on the cracking performance of the concrete than temperature stress.
According to the above analysis, the temperature stress influence factor of the base plate 1 is about 0.48, and the shrinkage stress influence factor is about 0.52.
(2) Side wall 2
From the analysis of temperature stress angle, the thickness of the side wall 2 is relatively smaller, the side wall is just like the bottom plate 1, the highest temperature rise caused by the hydration heat of the concrete is relatively not large, and the temperature difference of the structural part is not large, so that the influence of the temperature stress on the cracking performance of the side wall 2 is smaller, and the anti-cracking purpose is easy to achieve through maintenance means such as heat preservation or temperature reduction.
From the analysis of shrinkage stress angle, as shown in fig. 2, the side surface of the side wall 2 is restrained by the underground enclosure structure 4, the bottom is restrained by the plate surfaces of the bottom plate 1 and the middle plate poured first, the external restraint stress is larger, and especially, the construction joint 21 near the bottom of the armpit angle 3 and the middle part of the side wall 2 section is easy to form cracking, so that the shrinkage stress has a larger influence on the concrete cracking performance of the side wall 2.
In conclusion, in early growth of concrete, shrinkage stress has a larger influence on cracking performance of the concrete than temperature stress.
According to the above analysis, the temperature stress influence factor of the side wall 2 is about 0.35, and the influence factor of the shrinkage stress is about 0.65.
(3) Top plate 5 and middle plate
From the analysis of temperature stress angle, the thickness of the top plate 5 and the middle plate is relatively smaller, the two sides of the plate surface and the model surface are used for radiating, the highest temperature rise caused by the hydration heat of the concrete is relatively smaller, and the temperature difference of the part structure is smaller, so that the influence of the temperature stress on the cracking performance of the top plate 5 and the middle plate is smaller, and the anti-cracking purpose is realized by curing means such as heat preservation or temperature reduction.
From the analysis of shrinkage stress angle, as shown in fig. 3, the top plate 5 and the middle plate are cast by a formwork, the formwork belongs to weak constraint, but the joints of the top plate 5 and the middle plate and the side wall 2 are constrained by the side wall 2 cast first, and the side underground enclosure structure 4 is constrained, so that the influence of the shrinkage stress on the concrete cracking performance of the top plate 5 and the middle plate needs to be properly considered in combination of the two constraints.
In summary, the concrete mixing ratio between the top plate 5 and the middle plate needs to comprehensively consider the dual factors of the temperature stress and the shrinkage stress.
In early stage of concrete growth, shrinkage stress has a larger influence on concrete cracking performance than temperature stress.
According to the above analysis, the shrinkage stress influence factor of the top plate 5 and the middle plate was about 0.51, and the influence factor of the temperature stress was about 0.49.
According to the influence factors, the influence factors of the concrete cracking performance of different part structures are obtained, so that the concrete mixing ratio is adjusted, the influence of temperature stress or shrinkage stress is reduced pertinently, and the influence of the temperature stress or shrinkage stress on the concrete cracking performance is balanced.
When the temperature stress is a main influencing factor, the consumption of silicate cement in the concrete cementing material is required to be reduced, namely, the hydration heat phenomenon of the concrete is reduced, and the highest temperature rise caused by the hydration heat is reduced so as to reduce the inner surface temperature difference and reduce the temperature stress. Correspondingly, the mixing amount of the fly ash and the slag powder is increased, the shrinkage rate of the concrete is improved, the shrinkage stress is increased, and the shrinkage stress and the temperature stress are approximately balanced.
When shrinkage stress is a main influencing factor, the mixing proportion of slag powder in the concrete cementing material needs to be reduced, namely, the shrinkage rate of the concrete is reduced, and the shrinkage stress is reduced. Correspondingly, the usage amount of silicate cement is increased, the hydration heat phenomenon is increased, the temperature stress is increased, and the shrinkage stress and the temperature stress are approximately balanced.
Thus, in the concrete cementing material of the bottom plate 1, the ground slag powder accounts for no more than 15.00%; in the concrete cementing material of the side wall 2, the proportion of ground slag powder is not more than 10.00%; in the concrete cementing material of the top plate 5 and the middle plate, the proportion of the ground slag powder is not more than 16.00%.
Under the same requirement of the design strength grade and the impermeability grade, namely, the same requirement on the concrete strength and the impermeability, different part structures of subways, different constraint conditions and different processes, the factors influencing the early cracking performance of the concrete are different, and the concrete mixing proportion with differentiation is designed through the analysis and a large number of tests and detection, so that the influence of temperature stress and shrinkage stress on the cracking performance of the concrete is balanced, the quality of the concrete structure on site is improved, the cracking of the concrete is further prevented, and the waterproof and impermeable purposes are achieved.
According to the requirement of consistency of concrete materials and mix proportion of an underground main structure in the prior art, for example, 4.2.1 prescribes the selection and quality of cement in the national standard of mass concrete construction, and the like, and the impermeability of the concrete also has corresponding standards and requirements, for example, 4.1.4 prescribes the design impermeability grade requirement of subway station structure concrete in the underground engineering waterproof technical specification, and details are not repeated here.
On the basis, the standard concrete mix ratio is determined according to the environment, the construction process, the concrete mix ratio and the maintenance condition, and the standard concrete mix ratio uses the standard of the same strength and impermeability level, and does not consider different anti-cracking requirements in different structural parts, namely, stress conditions of temperature stress and shrinkage stress in structures of all parts.
Based on the requirements of the prior art and the standard, the concrete mixing ratio is preferably obtained after the invention is subjected to field test and detection as follows.
Concrete mix ratio of the bottom plate 1: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 20.00-25.00%, the mixing amount of the slag powder is 10.00-15.00%, and the mixing amount of the additive is 1.50-2.00%.
Concrete mix ratio of the side wall 2: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 25.00-30.00%, the mixing amount of the slag powder is 0.00%, and the mixing amount of the additive is 1.50-2.00%.
Concrete mix ratio of top plate 5 and middle plate: the water-cement ratio is 0.38-0.40, the sand ratio is 43.00%, the mixing amount of the fly ash is 20.00-25.00%, the mixing amount of the slag powder is 10.00%, and the mixing amount of the additive is 1.50-2.00%.
Embodiment one:
Concrete mix ratio of the bottom plate 1: the water-gel ratio is 0.38, the mixing amount of the fly ash is 25.00%, the slag powder is 10.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume a volume weight of 2360.00kg/m 3, wherein the cement content is 400kg/m 3, the cement content is 260.00kg/m 3, the fly ash content is 100.00kg/m 3, the slag powder content is 40.00kg/m 3, the sand content is 777.00kg/m 3, the crushed stone content is 1030kg/m 3, and the mixing water content is 146.00kg/m 3.
Embodiment two:
Concrete mix ratio of the bottom plate 1: the water-cement ratio is 0.38, the mixing amount of the fly ash is 25.00%, the mixing amount of the slag powder is 10.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume that the volume weight is 2360.00kg/m 3, the cement content is 400.00kg/m 3, the cement content is 240.00kg/m 3, the fly ash content is 100.00kg/m 3, the slag powder content is 60.00kg/m 3, the sand content is 777.00kg/m 3, the crushed stone content is 1030.00kg/m 3, and the mixing water content is 146.00kg/m 3.
Embodiment III:
Concrete mix ratio of the bottom plate 1: the water-cement ratio is 0.40, the mixing amount of the fly ash is 25.00%, the mixing amount of the slag powder is 10.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume a volume weight of 2360.00kg/m 3, wherein the cement content is 383.00kg/m 3, the cement content is 249.00kg/m 3, the fly ash content is 96.00kg/m 3, the slag powder content is 38.00kg/m 3, the sand content is 783.00kg/m 3, the crushed stone content is 1040.00kg/m 3, and the mixing water content is 147.00kg/m 3.
Embodiment four:
Concrete mix ratio of the bottom plate 1: the water-cement ratio is 0.40, the mixing amount of the fly ash is 20.00%, the mixing amount of the slag powder is 15.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume a volume weight of 2360.00kg/m 3, wherein the cement content is 383.00kg/m 3, the cement content is 249.00kg/m 3, the fly ash content is 77.00kg/m 3, the slag powder content is 57.00kg/m 3, the sand content is 783.00kg/m 3, the crushed stone content is 1040.00kg/m 3, and the mixing water content is 147.00kg/m 3.
Fifth embodiment:
Concrete mix ratio of the side wall 2: the water-cement ratio is 0.38, the mixing amount of the fly ash is 30.00%, the mixing amount of the slag powder is 0.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume that the volume weight is 2360.00kg/m 3, the cement content is 400.00kg/m 3, the cement content is 280.00kg/m 3, the fly ash content is 120.00kg/m 3, the slag powder content is 0.00kg/m 3, the sand content is 777.00kg/m 3, the crushed stone content is 1030.00kg/m 3, and the mixing water content is 146.00kg/m 3.
Example six:
Concrete mix ratio of the side wall 2: the water-cement ratio is 0.40, the mixing amount of the fly ash is 28.00%, the mixing amount of the slag powder is 0.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume a volume weight of 2360.00kg/m 3, wherein the cement content is 383.00kg/m 3, the cement content is 275.00kg/m 3, the fly ash content is 108.00kg/m 3, the slag powder content is 0.00kg/m 3, the sand content is 783.00kg/m 3, the crushed stone content is 1040.00kg/m 3, and the mixing water content is 147.00kg/m 3.
Embodiment seven:
Concrete mix ratio of the side wall 2: the water-cement ratio is 0.40, the mixing amount of the fly ash is 25.00%, the mixing amount of the slag powder is 0.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume that the volume weight is 2360.00kg/m 3, the cement content is 383.00kg/m 3, the cement content is 287.00kg/m 3, the fly ash content is 96.00kg/m 3, the slag powder content is 0.00kg/m 3, the sand content is 783.00kg/m 3, the crushed stone content is 1040.00kg/m 3, and the mixing water content is 147.00kg/m 3.
Example eight:
Concrete mix ratio of top plate 5 and middle plate: the water-cement ratio is 0.38, the mixing amount of the fly ash is 25.00%, the mixing amount of the slag powder is 10.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume that the volume weight is 2360.00kg/m 3, the cement content is 400.00kg/m 3, the cement content is 260.00kg/m 3, the fly ash content is 100.00kg/m 3, the slag powder content is 40.00kg/m 3, the sand content is 777.00kg/m 3, the crushed stone content is 1030.00kg/m 3, and the mixing water content is 146.00kg/m 3.
Example nine:
Concrete mix ratio of top plate 5 and middle plate: the water-cement ratio is 0.40, the mixing amount of the fly ash is 20.00%, the mixing amount of the slag powder is 10.00%, the sand ratio is 43.00%, and the mixing amount of the additive is 1.50-2.00%. Assume a volume weight of 2360.00kg/m 3, wherein the cement content is 383.00kg/m 3, the cement content is 268.00kg/m 3, the fly ash content is 77.00kg/m 3, the slag powder content is 38.00kg/m 3, the sand content is 783.00kg/m 3, the crushed stone content is 1040.00kg/m 3, and the mixing water content is 147.00kg/m 3.
Embodiments of the base plate 1 are specifically shown in the following table:
examples of side walls 2 are shown in the following table:
examples of top plate 5 and middle plate are shown in the following table:
| Concrete mixing ratio | Top plate and middle plate | Top plate and middle plate |
| Ratio of water to gel | 0.38 | 0.40 |
| Fly ash content (%) | 25.00 | 20.00 |
| Slag powder blend (%) | 10.00 | 10.00 |
| Sand ratio (%) | 43.00 | 43.00 |
| Additive amount (%) | 1.50-2.00 | 1.50-2.00 |
| Assume that the bulk density (kg/m 3) | 2360.00 | 2360.00 |
| Cementing material dosage (kg/m 3) | 400.00 | 383.00 |
| Cement (kg/m 3) | 260.00 | 268.00 |
| Fly ash (kg/m 3) | 100.00 | 77.00 |
| Slag powder (kg/m 3) | 40.00 | 38.00 |
| Sand (kg/m 3) | 777.00 | 783.00 |
| Macadam (kg/m 3) | 1030.00 | 1040.00 |
| Mixing water (kg/m 3) | 146.00 | 147.00 |
In all the above examples, the sand and crushed stone contained a small amount of moisture, about 7kg/m 3, calculated in the blending ratio, calculated in the assumed bulk weight.
Wherein, the selection, quality and application technology of the admixture should meet the relevant regulations of the current national standards of concrete admixture GB 8076 and concrete admixture application technical Specification GB 50119. In addition, the following conditions should be satisfied:
(1) The variety and the doping amount of the additive should be determined after the test;
(2) The influence coefficient of the additive on the performances of the hardened concrete such as shrinkage and the like is defined;
(3) High volume concrete casting bodies in high durability or cold areas need to be made with air entraining agents or water reducing agents.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (3)
1. The method for determining the differential mixing proportion of the concrete of the subway station structure is characterized by calculating and analyzing the temperature stress and the shrinkage stress of the concrete pouring body according to the structural characteristics of the concrete pouring body to obtain the influence factors of the temperature stress and the shrinkage stress of the concrete pouring body, and changing the mixing proportion of the concrete according to the influence factors;
The main structure of the underground engineering is subdivided into different structural parts, the concrete main structure comprises a bottom plate, side walls, a top plate and a middle plate, the specific gravity of cracking caused by the influence of temperature stress and shrinkage stress of each structural part is analyzed and calculated, temperature stress influence factors and shrinkage stress influence factors are respectively obtained, the existing concrete mixing ratio is subjected to differential correction according to the specific gravity of the temperature stress influence factors and the shrinkage stress influence factors, and the strength index, the anti-permeability index and the anti-cracking index of the concrete are balanced;
In early stage of concrete growth, the maximum influence factor of temperature stress is hydration heat release, the concrete pouring body releases 80% of shrinkage stress of the structure in 2-7 days in early stage, the temperature stress influence factor of the bottom plate is smaller than the shrinkage stress influence factor, the temperature stress influence factor of the bottom plate is 0.48, the shrinkage stress influence factor is 0.52, and the proportion of ground slag powder in the concrete cementing material of the bottom plate is not more than 15.00%;
in early stage of concrete growth, the temperature stress influence factor of the side wall is smaller than the shrinkage stress influence factor, the temperature stress influence factor of the side wall is 0.35, the influence factor of the shrinkage stress is 0.65, and the proportion of ground slag powder in the concrete cementing material of the side wall is not more than 10.00%;
in early stage of concrete growth, shrinkage stress influence factors of the top plate and the middle plate are larger than temperature stress influence factors, the shrinkage stress influence factors of the top plate and the middle plate are 0.51, the influence factors of the temperature stress are 0.49, and the proportion of ground slag powder in the concrete cementing material of the top plate and the middle plate is not more than 16.00%.
2. The method for determining the differential concrete mix ratio of the subway station structure according to claim 1, wherein the standard concrete mix ratio is determined according to the environment, the construction process, the concrete mix ratio and the maintenance condition, and when the temperature stress influence factor of the concrete casting body is larger than the shrinkage stress influence factor, the Portland cement dosage is reduced from the standard concrete mix ratio.
3. The method for determining the differential concrete mix ratio of the subway station structure according to claim 1, wherein the standard concrete mix ratio is determined according to the environment, the construction process, the concrete mix ratio and the maintenance condition, and when the shrinkage stress influence factor of the concrete casting body is larger than the temperature stress influence factor, the slag powder mixing amount is reduced from the standard concrete mix ratio.
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