Concrete pouring crack control method in abnormal environmental region

Abstract

The invention discloses a concrete pouring crack control method in an abnormal environmental region, and the method comprises the steps: collecting the data information of concrete pouring in the abnormal environmental region, constructing a shrinkage model of a multi-field coupling mechanism, considering the material, structure and environmental factors, and carrying out the quantitative evaluation of the cracking risk of a concrete structure, the irrigation work in the abnormal environment region is controlled according to the quantitative evaluation result, the irrigation work is adjusted in real time according to the parameter information of the irrigation process, after the irrigation work is completed, heat preservation and moisture preservation maintenance and supervision are conducted, and generation of early cracks and temperature self-constraint cracks is prevented. According to the method, the long-term influence of the temperature in the abnormal environment is considered, secondary calculation is performed on the cracking risk of the concrete, the change rule of the temperature is considered, the cracking risk of the concrete structure is corrected, the accuracy of concrete cracking risk assessment is improved, and the whole process of accurate and efficient cracking control is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete pouring crack control, and in particular to a concrete pouring crack control method in an abnormal environment area. Background Art

[0002] During the construction process, many construction projects are located in extreme environments such as large temperature differences, low air pressure, high temperature, strong ultraviolet rays, high wind speeds, and sudden hail and snowfall due to their unique geographical structure and location. The construction safety of concrete projects faces severe challenges. At present, there is insufficient research experience on the bearing capacity and durability of concrete in areas with abnormal environments, and the inability to ensure the safety performance of concrete has become a major challenge for engineering construction.

[0003] In the process of using concrete for construction work, attention to crack prevention and control of concrete has always been a key component of concrete research. In the existing technology, most of the performance evaluation of concrete is carried out in a conventional environment, and crack control guidance is provided based on the evaluation results, aiming to preliminarily reveal the impact of the current ambient temperature on the mechanical properties and hydration characteristics of concrete, indicating that temperature has a significant impact on concrete performance. However, the compressive strength and tensile strength of concrete are not taken into account in extreme environments, which leads to the fact that crack control research cannot fully reflect the real environment of the concrete construction process, and lacks comprehensive research considering the performance of concrete in abnormal environmental areas. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling cracking of concrete pouring in areas with abnormal environments, so as to solve the above-mentioned problems existing in the prior art.

[0005] The specific application is as follows:

[0006] A method for controlling cracking of concrete pouring in an abnormal environment region is provided, which is characterized by comprising the following steps: step one: collecting data information of concrete pouring in an abnormal environment region; step two: constructing a shrinkage model of a multi-field coupling mechanism, considering material, structure and environmental factors, and quantitatively evaluating the cracking risk of the concrete structure; step three: controlling the pouring work in the abnormal environment region according to the quantitative evaluation result, and adjusting the pouring operation in real time according to the parameter information of the pouring process; step four: after completing the pouring operation, performing thermal insulation, moisture retention maintenance and supervision.

[0007] The data information of concrete pouring in step 1 includes mix ratio data, material performance parameters, raw material temperature, ambient temperature, temperature distribution information and stress and strain state information.

[0008] In the step 2, a shrinkage model of a multi-field coupling mechanism is constructed, and the cracking risk of the concrete structure is quantitatively evaluated by considering material, structural and environmental factors, including:

[0009] Calculate concrete cracking risk factor:

[0010]

[0011] Among them, η is the concrete cracking risk factor, σ(t) is the maximum tensile stress of concrete at time t / MPa, and f t (α) is the tensile strength of concrete at time t / MPa;

[0012] The elastic modulus and tensile strength of concrete are necessary parameters for calculating shrinkage stress and crack risk. The calculation formula is as follows:

[0013]

[0014] Where, E(α) is the early elastic modulus / GPa, f t (α) is the tensile strength at time t / MPa, E ∞ is the final elastic modulus / GPa, f t ∞ is the ultimate tensile strength / MPa, α o and α ∞ are the initial and final values ​​of the degree of hydration α, p and q are exponential constants with values ​​of 0.5 and 1, respectively;

[0015]

[0016] Where α is the degree of hydration, To drive the chemical affinity of the hydration reaction, Q α is the activation energy, R is a constant, B1, B2 and γ are the model parameters that control the hydration reaction rate, α ∞ is the final value of the degree of hydration.

[0017] In abnormal environment areas for a long time, concrete structures are greatly affected by changes in ambient temperature. It is necessary to perform secondary calculations on the risk of concrete cracking, consider the temperature change law, evaluate the risk of concrete structure cracking, and consider the impact of temperature on the concrete pouring process:

[0018]

[0019] Where T is the annual rate of change of temperature, is the annual average temperature / ℃, A is the annual temperature change / ℃, T0 is the lowest temperature in a year / ℃, T m is the highest temperature in a year / ℃;

[0020]

[0021] Where K T is the temperature influence coefficient, T is the annual rate of change of temperature, T1 is the initial temperature value, is the annual average temperature / ℃, W is the water consumption, which is preliminarily determined according to the relevant concrete mix design specifications or empirical data, and C is the cement consumption, which is calculated according to the design strength grade of concrete, the type and strength grade of cement;

[0022]

[0023] Among them, f0 is the mix strength of concrete, f k is the design strength grade, f e is the strength grade of cement, σ is the standard deviation of strength, α a , α b It is an empirical coefficient, which is determined according to different cement types and aggregate conditions, and the cement dosage is obtained from it.

[0024] Calculation of cracking risk factor considering temperature effect:

[0025]

[0026] Among them, f c (k) is the function of the evolution of concrete compressive strength, k is an internal variable related to the degree of hydration α and temperature, is the final compressive strength of concrete under standard conditions, A and B are material parameters;

[0027] The tensile strength of concrete is related to its compressive strength:

[0028]

[0029] Among them, (E ∞ )' is the final elastic modulus after considering the temperature effect / GPa, (f t ∞ )' is the ultimate tensile strength after considering the temperature effect / MPa, k1 and k2 are constants;

[0030] The final elastic modulus after considering the temperature effect (E ∞ )' and ultimate tensile strength (f t ∞ )' is substituted into formula (2) and (3), and the concrete cracking risk factor after considering the temperature effect is obtained as follows:

[0031]

[0032] Among them, η' is the concrete cracking risk factor after considering the temperature effect, σ(t)' is the maximum tensile stress of concrete at time t after considering the temperature effect / MPa, and f t (α)' is the tensile strength of concrete at time t after considering the influence of temperature / MPa.

[0033] The concrete cracking risk assessment criteria are obtained to guide the subsequent pouring work. When η'>1.0, the concrete will definitely crack. When 0.7<η'≤1.0, the concrete has a greater risk of cracking. When η'≤0.7, the concrete will basically not crack, and the non-cracking guarantee rate is ≥95%.

[0034] In the step three, the pouring work in the abnormal environment area is controlled according to the quantitative evaluation results, and the pouring operation is adjusted in real time according to the parameter information of the pouring process, including: adjusting the type and amount of cement, water-cement ratio, aggregate, mixed water temperature, admixture ratio and mix ratio design in the concrete pouring process according to the quantitative evaluation results, recording the concrete pouring start time, end time and speed changes during the pouring process, and adjusting the pouring speed for different temperature periods.

[0035] For concrete pouring of multi-layer or higher structures, it is necessary to collect the pouring height of each layer, set a reasonable layer height, record the interval time of layer pouring and control it, record the vibration method, vibration time and vibration position and adjust them according to the actual pouring situation.

[0036] The thermal insulation and moisture retention maintenance and supervision described in step 4 include: maintenance using "two cloths and one film", i.e. geotextile + plastic film + quilt. During the maintenance period, water is sprinkled under the plastic film to keep the geotextile moist and the quilt dry. In winter, the number of thermal insulation quilt layers is increased depending on the temperature. In rainy, snowy and windy seasons, an extra layer of rainproof cloth is covered outside the quilt.

[0037] The supervision includes assigning a dedicated person to monitor the temperature monitoring data, and adjusting the cooling water flow time and insulation measures according to the temperature monitoring data, reasonably organizing the construction, reducing the time difference between the pouring of the upper and lower layers of concrete, and before pouring the upper layer of concrete, first pour a 5cm thick layer of mortar on the interface between the new and old concrete; specially collect meteorological information, and if a sudden drop in temperature is found, immediately strengthen the insulation work of the concrete at the construction site; after the pouring of the corridor and empty box structure is completed, immediately use rainproof cloth to seal the openings and holes of the corridor and empty box.

[0038] Compared with the prior art, the embodiments of the present invention achieve the following beneficial effects: the present invention provides a method for controlling cracks in concrete pouring in areas with abnormal environments, constructs a shrinkage model of a multi-field coupling mechanism, considers material, structural and environmental factors, quantitatively evaluates the cracking risk of concrete structures, and considers the long-term impact of temperature in abnormal environments during the evaluation process, performs a secondary calculation of the risk of concrete cracking, considers the temperature variation law, corrects the cracking risk of concrete structures, improves the accuracy of concrete cracking risk assessment, controls pouring work in areas with abnormal environments based on the risk assessment results, and performs thermal insulation and moisture maintenance and supervision after the pouring operation is completed to prevent the occurrence of early cracks and temperature self-constrained cracks, thereby achieving an accurate and efficient crack control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention provides a flow chart of a method for controlling cracking during concrete pouring in an abnormal environment. DETAILED DESCRIPTION

[0040] The following will be combined with the attached Figure 1 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The present invention provides a method for controlling cracking of concrete pouring in an abnormal environment region, such as Figure 1 As shown, the following steps are included: Step 1: Collect data information on concrete pouring in abnormal environmental areas; Step 2: Construct a shrinkage model of a multi-field coupling mechanism, consider material, structural and environmental factors, and conduct a quantitative assessment of the cracking risk of the concrete structure; Step 3: Control the pouring work in the abnormal environmental area according to the quantitative assessment results, and adjust the pouring operation in real time according to the parameter information of the pouring process; Step 4: After completing the pouring operation, perform thermal insulation and moisture maintenance and supervision to prevent the occurrence of early cracks and temperature self-constrained cracks.

[0042] Among them, the data information of concrete pouring in step one includes mix ratio data, material performance parameters, raw material temperature, ambient temperature, temperature distribution information and stress and strain state information.

[0043] Specifically, the data information of concrete pouring includes mix ratio data: the ratio of cement, sand, stone, water and admixtures. For example, the ratio of cement to water / water-cement ratio directly affects the strength and shrinkage performance of concrete. The higher the water-cement ratio, the better the fluidity of the concrete, but the strength may decrease, the shrinkage increases, and cracks are more likely to occur. Therefore, it is necessary to accurately collect the mix ratio parameters of water-cement ratio and sand ratio to provide basic data for subsequent crack control.

[0044] Material performance parameters: such as the type and strength grade of cement. Different types of cement (such as ordinary Portland cement, low-heat Portland cement, etc.) have different hydration heat. The hydration heat generated by low-heat Portland cement is relatively low, which helps to reduce cracks caused by temperature stress in large-volume concrete pouring. It is also necessary to collect the type and performance parameters of admixtures (such as water reducers, expansive agents, etc.). Water reducers can improve the workability of concrete, and expansive agents can compensate for the shrinkage of concrete. Understanding the performance of these admixtures is crucial to crack control.

[0045] Raw material temperature: Collect the temperature of concrete raw materials (cement, sand, stone and water). In summer, the temperature of raw materials may be high, which will increase the temperature of concrete entering the mold, resulting in an increase in the peak temperature inside the concrete and an increase in the risk of temperature cracks. In winter, the temperature of concrete may be too low, delaying the setting time of concrete and even causing frost damage cracks. Therefore, real-time collection of raw material temperature helps to take temperature control measures in advance.

[0046] Ambient temperature: In areas with abnormal environments, ambient temperature is one of the key factors affecting the occurrence of concrete cracks. In a high temperature environment, the moisture in the concrete evaporates quickly, which easily causes plastic shrinkage cracks; in a low temperature environment, the concrete may suffer from freezing damage and crack.

[0047] Temperature distribution information: After concrete is poured, the temperature inside it will change due to the heat of cement hydration. By arranging temperature sensors at different locations inside the concrete structure (such as the center, surface, different depths, etc.), temperature distribution data can be collected. Understanding the temperature distribution helps to determine whether there is excessive temperature stress inside the concrete. For example, when the temperature difference between the inside and outside of the concrete exceeds 25°C, cooling or insulation measures need to be taken to prevent temperature cracks.

[0048] Stress and strain state information: Collecting stress and strain data inside the concrete structure can intuitively understand whether there is a risk of cracks in the concrete. For example, when the tensile strain of the concrete exceeds its limit tensile strain, cracks may occur. The strain changes of the concrete during the pouring process and the initial hardening stage are measured by sensors such as strain gauges, and the stress state is calculated in combination with the elastic modulus parameters of the concrete, so as to timely discover potential crack hazards.

[0049] In the step 2, a shrinkage model of a multi-field coupling mechanism is constructed, and the cracking risk of the concrete structure is quantitatively evaluated by considering material, structural and environmental factors, including:

[0050] Calculate concrete cracking risk factor:

[0051]

[0052] Among them, η is the concrete cracking risk factor, σ(t) is the maximum tensile stress of concrete at time t / MPa, and f t (α) is the tensile strength of concrete at time t / MPa;

[0053] The elastic modulus and tensile strength of concrete are necessary parameters for calculating shrinkage stress and crack risk. The calculation formula is as follows:

[0054]

[0055] Where, E(α) is the early elastic modulus / GPa, f t(α) is the tensile strength at time t / MPa, E ∞ is the final elastic modulus / GPa, f t ∞ is the ultimate tensile strength / MPa, α o and α ∞ are the initial and final values ​​of the degree of hydration α, p and q are exponential constants with values ​​of 0.5 and 1, respectively;

[0056]

[0057]

[0058] Where α is the degree of hydration, To drive the chemical affinity of the hydration reaction, Q α is the activation energy, R is a constant, B1, B2 and γ are the model parameters that control the hydration reaction rate, α ∞ is the final value of the degree of hydration.

[0059] In abnormal environment areas for a long time, concrete structures are greatly affected by changes in ambient temperature. It is necessary to perform secondary calculations on the risk of concrete cracking, consider the temperature change law, evaluate the risk of concrete structure cracking, and consider the impact of temperature on the concrete pouring process:

[0060]

[0061] Where T is the annual rate of change of temperature, is the annual average temperature / ℃, A is the annual temperature change / ℃, T0 is the lowest temperature in a year / ℃, T m is the highest temperature in a year / ℃;

[0062]

[0063] Where K T is the temperature influence coefficient, T is the annual rate of change of temperature, T1 is the initial temperature value, is the annual average temperature / ℃, W is the water consumption, which is preliminarily determined according to the relevant concrete mix design specifications or empirical data, and C is the cement consumption, which is calculated according to the design strength grade of concrete, the type and strength grade of cement;

[0064]

[0065] Among them, f0 is the mix strength of concrete, f k is the design strength grade, f e is the strength grade of cement, σ is the standard deviation of strength, α a , α bIt is an empirical coefficient, which is determined according to different cement types and aggregate conditions, and the cement dosage is obtained from it.

[0066] Calculation of cracking risk factor considering temperature effect:

[0067]

[0068] Among them, f c (κ) is the function of the evolution of concrete compressive strength, κ is an internal variable related to the hydration degree α and temperature, is the final compressive strength of concrete under standard conditions, A and B are material parameters;

[0069] The tensile strength of concrete is related to its compressive strength:

[0070]

[0071] Among them, (E ∞ )' is the final elastic modulus after considering the temperature effect / GPa, (f t ∞ )' is the ultimate tensile strength after considering the temperature effect / MPa, k1 and k2 are constants;

[0072] The final elastic modulus after considering the temperature effect (E ∞ )' and ultimate tensile strength (f t ∞ )' is substituted into formula (2) and (3), and the concrete cracking risk factor after considering the temperature effect is obtained as follows:

[0073]

[0074] Among them, η' is the concrete cracking risk factor after considering the temperature effect, σ(t)' is the maximum tensile stress of concrete at time t after considering the temperature effect / MPa, and f t (α)' is the tensile strength of concrete at time t after considering the influence of temperature / MPa.

[0075] The concrete cracking risk assessment criteria are obtained to guide the subsequent pouring work. When η'>1.0, the concrete will definitely crack. When 0.7<η'≤1.0, the concrete has a greater risk of cracking. When η'≤0.7, the concrete will basically not crack, and the non-cracking guarantee rate is ≥95%.

[0076] In the step three, the pouring work in the abnormal environment area is controlled according to the quantitative evaluation results, and the pouring operation is adjusted in real time according to the parameter information of the pouring process, including: adjusting the type and amount of cement, water-cement ratio, aggregate, mixed water temperature, admixture ratio and mix ratio design in the concrete pouring process according to the quantitative evaluation results, recording the concrete pouring start time, end time and speed changes during the pouring process, and adjusting the pouring speed for different temperature periods.

[0077] Taking the design of concrete mix ratio in high temperature areas as an example, the type and amount of cement is low heat cement: using low heat cement in high temperature environment can slow down the release of hydration heat and reduce the risk of temperature cracks; reduce the amount of cement: try to reduce the amount of cement to reduce the degree of temperature rise inside the concrete, and at the same time, mineral admixtures (such as fly ash and slag) can be added to replace part of the cement. Low water-cement ratio: choose a lower water-cement ratio to reduce capillary pores and increase the density of concrete, enhance durability and impermeability. Aggregate selection of low water absorption aggregate: select aggregate with low water absorption to reduce the loss of water inside the concrete, and ensure that the aggregate temperature is kept low before mixing to avoid thermal expansion of aggregate at high temperature causing volume change of concrete. Mixing water temperature selects cooling mixing water: use ice water or cooled water to adjust the initial temperature of concrete, control temperature rise, and reduce the impact of hydration heat on concrete. Admixture selection of mineral admixtures: such as fly ash, slag, etc., can reduce hydration heat and improve workability and durability. Water reducing agent: Use high-efficiency water reducing agent to reduce water consumption and improve the fluidity and strength of concrete. Concrete mix design adjustment: By appropriately increasing the sand ratio: to improve the cohesiveness of concrete and improve construction performance. Extend the mixing time: Appropriately extend the mixing time to make the mixture fully uniform, especially in the low water-cement ratio design, to ensure the strength, durability and workability of the concrete.

[0078] Specifically, record the start and end time of concrete pouring and the speed changes during the pouring process. Pouring too fast may cause the air inside the concrete to be unable to be discharged in time, forming pores, reducing the density of the concrete, and increasing the possibility of cracks. At the same time, the pouring speed in different time periods can also reflect the situation during the construction process. For example, slowing down the pouring speed appropriately during periods of high temperature is conducive to controlling the temperature of the concrete.

[0079] For concrete pouring of multi-layer or higher structures, it is necessary to collect the pouring height of each layer. Setting a reasonable layer height will help dissipate heat from the concrete and prevent temperature cracks. The interval time of layered pouring should be recorded and controlled. The vibration method, vibration time and vibration position should be recorded and adjusted according to the actual pouring situation.

[0080] Specifically, for concrete pouring of multiple layers or higher structures, it is necessary to collect the height of each pouring layer. For example, in the layered pouring of large-volume concrete, a reasonable layer height (such as 30-50 cm) helps the concrete dissipate heat and prevent temperature cracks. It is also necessary to record the interval time of layered pouring. Too long an interval time may affect the bonding between concrete layers and cause interlayer cracks. The vibration conditions include the vibration method (such as inserted vibrating rods, flat vibrators, etc.), vibration time and vibration position. Sufficient and reasonable vibration can make the concrete more compact, reduce porosity, and improve crack resistance. If the vibration time is too short, the concrete is not dense enough; if the vibration time is too long, it may cause concrete segregation, which will affect the cracks. By collecting data such as the insertion depth and vibration frequency of the vibrating rod through sensors, the vibration process can be better controlled.

[0081] Taking pouring operations in high-temperature areas as an example, the temperature of concrete entering the mold is controlled within 32°C, and the time from concrete mixing to the final completion of pouring is controlled within 90 minutes. The wall and top plate concrete pouring is poured using a pump truck with an arm length of 56m. The concrete pouring should be poured in layers, and the thickness of each layer should not exceed 40cm. The pouring time between layers should not be too long to avoid cold joints. The entire pouring process should be kept continuous and not interrupted. At the same time, attention should be paid to controlling the wall pouring speed to no more than 2m / h to prevent the template from bearing too much concrete side pressure in a short time. Appropriate vibration technology should be adopted, and the vibration should be carried out using a 50-type inserted vibrator. The time of each vibration is controlled within 15-20 seconds, and the distance between the vibration points is between 40-50cm. When vibrating, the vibrator should be inserted into the lower layer of concrete by 10-15cm to ensure the effective combination of the upper and lower layers of concrete. At the same time, attention should be paid to avoiding steel bars, embedded parts, truncated cone nuts and embedded anchor rods. The minimum distance between the vibrator and the side mold is controlled at 5-10cm, and the side mold must not be touched. The vibrating rod should be inserted quickly and pulled out slowly, and vibrated until the concrete surface is flat and there is no slurry or bubbles. No missing vibration or over-vibration is allowed. It is strictly forbidden to add water to the concrete during the pouring process. If the concrete workability is found to be poor, the concrete tank truck should rotate 5 times at a constant speed, and then take other measures to strengthen vibration and improve workability.

[0082] The thermal insulation and moisture retention maintenance and supervision described in step 4 include: maintenance using "two cloths and one film", i.e. geotextile + plastic film + quilt. During the maintenance period, water is sprinkled under the plastic film to keep the geotextile moist and the quilt dry. In winter, the number of thermal insulation quilt layers is increased depending on the temperature. In rainy, snowy and windy seasons, an extra layer of rainproof cloth is covered outside the quilt to ensure the thermal insulation effect of the concrete.

[0083] The supervision includes assigning a dedicated person to monitor the temperature monitoring data, and adjusting the cooling water flow time and insulation measures according to the temperature monitoring data, reasonably organizing the construction, reducing the time difference between the pouring of the upper and lower layers of concrete, and before pouring the upper layer of concrete, first pour a 5 cm thick layer of mortar on the interface between the new and old concrete to reduce the foundation constraint coefficient; specially collect meteorological information, and if the temperature drops sharply, immediately strengthen the insulation of the concrete at the construction site to prevent cracks caused by rapid temperature loss of the concrete; after the pouring of the corridor and empty box structure is completed, immediately use rainproof cloth to seal the openings and holes of the corridor and empty box to prevent wind from causing temperature loss of the concrete.

[0084] Taking the maintenance in high temperature areas as an example, two temperature sensors are buried in the concrete to measure the temperature change process of the first large-volume concrete. The temperature probes are buried in the center and top surface of the bottom plate (the top probe is 50mm away from the concrete surface). During the maintenance process, the internal and surface temperatures of the concrete are continuously monitored to ensure that the maximum temperature inside the concrete does not exceed 70°C and the temperature difference between the inside and the surface does not exceed 20°C to prevent concrete cracking. Temperature measurement is carried out every two hours in the first 24 hours and every three hours in the next 24 hours. The measurement time is 5 days, or when the concrete reaches a constant temperature. All test items should be carried out immediately after the concrete is poured and continuously. The temperature sensor of the concrete is automatically monitored, and the temperature data is collected and analyzed after the test. After the concrete is poured, its surface is covered with a curing geotextile. During the curing period, water is continuously sprinkled to keep the geotextile and concrete surface moist. If necessary, a cement sill can be built on the edge of the concrete for water storage and maintenance. Due to the high temperature and extreme weather such as sandstorms, attention should be paid to fixing the geotextile during maintenance to prevent it from being damaged and causing the curing water to evaporate quickly.

[0085] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0086] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly recited in each claim. More specifically, as reflected in the claims below, inventive aspects lie in less than all the features of the individual embodiments disclosed above. Therefore, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, with each claim itself serving as a separate embodiment of the present invention.

[0087] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims below, any one of the claimed embodiments may be used in any combination.

Claims

1. A method for controlling cracking of concrete pouring in an abnormal environment area, characterized in that: The following steps are involved: Step 1: Collect data information on concrete pouring in abnormal environmental areas; Step 2: Construct a shrinkage model with multi-field coupling mechanism, consider material, structural and environmental factors, and conduct a quantitative assessment of the cracking risk of concrete structures; Step 3: Control the irrigation work in the abnormal environment area according to the quantitative evaluation results, and adjust the irrigation operation in real time according to the parameter information of the irrigation process; Step 4: After completing the watering operation, carry out thermal insulation, moisturizing maintenance and supervision.

2. A method for controlling cracking of concrete pouring in an abnormal environment area according to claim 1, characterized in that: The data information of concrete pouring in step 1 includes mix ratio data, material performance parameters, raw material temperature, ambient temperature, temperature distribution information and stress and strain state information.

3. The method for controlling cracking of concrete pouring in an abnormal environment region according to claim 1, characterized in that: In the step 2, a shrinkage model of a multi-field coupling mechanism is constructed, and the cracking risk of the concrete structure is quantitatively evaluated by considering material, structure and environmental factors, including: Calculate concrete cracking risk factor: Among them, η is the concrete cracking risk factor, σ(t) is the maximum tensile stress of concrete at time t / MPa, and f t (α) is the tensile strength of concrete at time t / MPa; The elastic modulus and tensile strength of concrete are necessary parameters for calculating shrinkage stress and crack risk. The calculation formula is as follows: Where, E(α) is the early elastic modulus / GPa, f t (α) is the tensile strength at time t / MPa, E ∞ is the final elastic modulus / GPa, f t ∞ is the ultimate tensile strength / MPa, α o and α ∞ are the initial and final values ​​of the degree of hydration α, p and q are exponential constants with values ​​of 0.5 and 1, respectively; Where α is the degree of hydration, To drive the chemical affinity of the hydration reaction, Q α is the activation energy, R is a constant, B1, B2 and γ are the model parameters that control the hydration reaction rate, α ∞ is the final value of the degree of hydration.

4. A method for controlling cracking of concrete pouring in an abnormal environment area according to claim 3, characterized in that: In abnormal environment areas for a long time, concrete structures are greatly affected by changes in ambient temperature. It is necessary to perform secondary calculations on the risk of concrete cracking, consider the temperature change law, evaluate the risk of concrete structure cracking, and consider the impact of temperature on the concrete pouring process: Where T is the annual rate of change of temperature, is the annual average temperature / ℃, A is the annual temperature change / ℃, T0 is the lowest temperature in a year / ℃, T m is the highest temperature in a year / ℃; Where K T is the temperature influence coefficient, T is the annual rate of change of temperature, T1 is the initial temperature value, is the annual average temperature / ℃, W is the water consumption, which is preliminarily determined according to the relevant concrete mix design specifications or empirical data, and C is the cement consumption, which is calculated according to the design strength grade of concrete, the type and strength grade of cement; Among them, f0 is the mix strength of concrete, f k is the design strength grade, f e is the strength grade of cement, σ is the standard deviation of strength, α a , α b It is an empirical coefficient, which is determined according to different cement types and aggregate conditions, and the cement dosage is obtained from it.

5. A method for controlling cracking of concrete pouring in an abnormal environment area according to claim 4, characterized in that: Calculation of cracking risk factor considering temperature effect: Among them, f c (κ) is the function of the evolution of concrete compressive strength, κ is an internal variable related to the hydration degree α and temperature, is the final compressive strength of concrete under standard conditions, A and B are material parameters; The tensile strength of concrete is related to its compressive strength: Among them, (E ∞ )' is the final elastic modulus after considering the temperature effect / GPa, (f t ∞ )' is the ultimate tensile strength after considering the temperature effect / MPa, k1 and k2 are constants; The final elastic modulus after considering the temperature effect (E ∞ )' and ultimate tensile strength (f t ∞ )' is substituted into formula (2) and (3), and the concrete cracking risk factor after considering the temperature effect is obtained as follows: Among them, η' is the concrete cracking risk factor after considering the temperature effect, σ(t)' is the maximum tensile stress of concrete at time t after considering the temperature effect / MPa, and f t (α)' is the tensile strength of concrete at time t after considering the influence of temperature / MPa.

6. A method for controlling cracking during concrete pouring in an abnormal environment area according to claim 5, characterized in that: The concrete cracking risk assessment criteria are obtained to guide the subsequent pouring work. When η'>1.0, the concrete will definitely crack. When 0.7<η'≤1.0, the concrete has a greater risk of cracking. When η'≤0.7, the concrete will basically not crack, and the non-cracking guarantee rate is ≥95%.

7. The method for controlling cracking of concrete pouring in an abnormal environment region according to claim 1, characterized in that: In the step three, the pouring work in the abnormal environment area is controlled according to the quantitative evaluation results, and the pouring operation is adjusted in real time according to the parameter information of the pouring process, including: adjusting the type and amount of cement, water-cement ratio, aggregate, mixed water temperature, admixture ratio and mix ratio design in the concrete pouring process according to the quantitative evaluation results, recording the concrete pouring start time, end time and speed changes during the pouring process, and adjusting the pouring speed for different temperature periods.

8. The method for controlling cracking of concrete pouring in an abnormal environment area according to claim 7, characterized in that: For concrete pouring of multi-layer or higher structures, it is necessary to collect the pouring height of each layer, set a reasonable layer height, record the interval time of layer pouring and control it, record the vibration method, vibration time and vibration position and adjust them according to the actual pouring situation.

9. The method for controlling cracking of concrete pouring in an abnormal environment region according to claim 1, characterized in that: The thermal insulation and moisture retention maintenance and supervision described in step 4 include: maintenance using "two cloths and one film", i.e. geotextile + plastic film + quilt. During the maintenance period, water is sprinkled under the plastic film to keep the geotextile moist and the quilt dry. In winter, the number of thermal insulation quilt layers is increased depending on the temperature. In rainy, snowy and windy seasons, an extra layer of rainproof cloth is covered outside the quilt.

10. A method for controlling cracking of concrete pouring in an abnormal environment area according to claim 9, characterized in that: The supervision includes assigning a dedicated person to monitor the temperature monitoring data, and adjusting the cooling water flow time and insulation measures according to the temperature monitoring data, reasonably organizing the construction, reducing the time difference between the pouring of the upper and lower layers of concrete, and before pouring the upper layer of concrete, first pour a 5cm thick layer of mortar on the interface between the new and old concrete; specially collecting meteorological information, and if a sudden drop in temperature is found, the construction site will immediately strengthen the insulation work of the concrete; after the pouring of the corridor and empty box structure is completed, immediately use rainproof cloth to seal the openings and holes of the corridor and empty box.

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