Mass concrete anti-cracking method and system based on unit engineering construction process evaluation and early warning

Abstract

The invention belongs to the field of mass concrete anti-cracking methods, and particularly provides a mass concrete anti-cracking method and system based on unit engineering construction process evaluation early warning, and the method comprises the steps: building a unit engineering construction process evaluation system; dividing unit engineering construction process evaluation grade standards; formulating a unit engineering construction process quality evaluation score deduction standard based on a score deduction method; carrying out comprehensive evaluation calculation and grade evaluation; and evaluating dynamic early warning regulation and control field measures based on the unit engineering construction process. According to the method, the anti-cracking problem of the mass concrete structure is decomposed into anti-cracking of a series of unit projects, aiming at each unit project, the anti-cracking of each unit project is realized by performing evaluation and early warning on the construction process of the unit project before bin opening, after bin opening, after bin collection and after formwork removal, and then the whole mass concrete structure does not generate harmful cracks.

Description

Technical Field

[0001] The present invention belongs to the field of mass concrete crack prevention methods, and in particular relates to a mass concrete crack prevention method and system based on unit engineering construction process evaluation and early warning. Background Art

[0002] During the construction period of large-volume concrete structures, due to temperature changes or other improper measures, large tensile stress often occurs, which often causes cracks in the structure, thereby destroying the integrity of the structure, reducing the durability of the structure, and bringing greater harm. Therefore, crack prevention during the construction period of large-volume concrete has always been a key and difficult issue that engineering units pay attention to.

[0003] my country has successively built a series of high concrete dam projects such as Xiaowan, Xiluodu, Baihetan, and Wudongde. In view of the temperature control and crack prevention problems during the construction period of these high concrete dam projects, Chinese scholars have adopted information, automation, intelligence, and intelligent technology, based on the closed-loop model of "perception-decision-control", and proposed and established a complete intelligent dam concrete temperature control and crack prevention system, which provides good guidance for the successful construction of these high concrete dam projects. However, with the advancement of my country's basic water conservancy project construction, in addition to the construction of a series of high concrete dam projects, my country has also built and planned to build a large number of concrete water projects such as sluices, ship locks, pumping stations, and aqueducts. Obviously, the intelligent dam concrete temperature control and crack prevention system is difficult to implement in the crack prevention of concrete water projects such as sluices, ship locks, pump stations, and aqueducts during the construction period. The reasons are as follows: (1) The former has too much hardware investment in temperature intelligent sensing, aggregate precooling, refrigeration water plants and other temperature control measures, which is difficult for general concrete water projects to bear; (2) The former also has a large investment in software such as calculation and analysis, which often involves the collaborative research of multiple universities and research institutes, which is difficult for general concrete water projects to achieve. (3) The former generally obtains a more comprehensive set of concrete thermal and mechanical properties through testing, while general concrete water projects, in addition to the necessary mix ratio test and 28d compressive strength test, generally refer to similar projects for other concrete thermal and mechanical properties, which to a certain extent reduces the reliability of the simulation calculation of temperature field and stress field during the construction period. (4) The former can combine the fully sensed temperature and stress to make accurate analysis and decision-making on the concrete dam structure during the construction period, while general concrete water projects, due to only a small amount of sensed temperature, rely more on the experience and judgment of engineering and technical personnel. In summary, for concrete water projects such as sluices, ship locks, pump stations, aqueducts, etc. during the construction period, the simulation calculation of temperature field and temperature stress field has inaccurate calculation parameters, boundary conditions and initial conditions, which makes it difficult for the simulation calculation results to effectively guide on-site construction; in addition, during on-site construction, measures such as water temperature are difficult to implement according to the design measures; whether the temperature control measures are in place, there is a certain degree of blindness and inspection danger of on-site implementation personnel, which leads to cracks in concrete water projects such as sluices, ship locks, pump stations, aqueducts, etc. during the construction period due to improper measures.

[0004] Regarding the crack prevention of large-volume concrete, Academician Zhu Bofang summarized the domestic and foreign experience and summarized it into the following five aspects: (1) Select reasonable structural form and joints and blocks; (2) Select concrete raw materials and optimize concrete mix ratio; (3) Strictly control concrete temperature to reduce foundation temperature difference, internal and external temperature difference and surface temperature drop; (4) Pay attention to the preparatory work before construction; (5) Strengthen construction management. So far, general concrete water projects have carried out a lot of work in terms of structural form, joints and blocks, and concrete mix ratio. Due to insufficient temperature and stress perception, the temperature control measures are unsatisfactory; in addition, the contradiction between demolition and progress has led to deficiencies in preparatory work before construction and construction management. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for preventing cracks in large-volume concrete based on evaluation and early warning of the construction process of unit projects, which decomposes the problem of preventing cracks in large-volume concrete structures into the prevention of cracks in a series of unit projects. For each unit project, by evaluating and early warning the construction process of the unit project before opening, after opening, after closing, and after demolding, the prevention of cracks in each unit project is achieved, thereby achieving the goal of preventing harmful cracks from occurring in the entire large-volume concrete structure.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preventing cracks in large-volume concrete based on evaluation and early warning of the unit engineering construction process, comprising the following steps: S1. Establish a unit project construction process evaluation system; S2. Classification of unit project construction process evaluation standards; S3. Formulate deduction standards for unit project construction process quality evaluation based on the deduction method; S4, comprehensive evaluation calculation and grade assessment; S5. Dynamic early warning and control of on-site measures based on unit project construction process evaluation.

[0007] In the preferred scheme, in the step S1, the unit project construction process evaluation system includes the evaluation system of the unit project before opening, after opening, after closing and after demolding, wherein the inspection before opening includes the appearance, position and size, material quality, and mechanical equipment; the inspection after opening includes the ambient temperature, concrete temperature, and construction quality; the inspection after closing includes the insulation condition in the low temperature season or the maintenance condition in the high temperature season, the water supply condition, and the concrete temperature condition; the inspection after demolding includes the insulation condition in the low temperature season or the maintenance condition in the high temperature season, and the concrete temperature condition.

[0008] In the preferred scheme, in step S2, a 4-level evaluation standard is used to divide the construction process of the concrete water engineering unit project into grades, and the evaluation grades before opening, after opening, after closing and after demolding are divided into grade A, grade B, grade C and grade D from best to worst.

[0009] In the preferred solution, in step S3, 100 points are assigned to each link of the unit engineering quality evaluation, and then allocated to each inspection item, inspection content and each evaluation level deduction score, thereby formulating the deduction standard for the quality evaluation status of the mass concrete unit engineering.

[0010] In a preferred solution, in step S4, the comprehensive evaluation calculation and grade assessment include the following steps: S401. Invite evaluation experts to rate the importance of the four construction processes: before warehouse opening, after warehouse opening, after warehouse closing, and after formwork removal; S402, use the Critic method to assign weights to the four processes. The calculation process is as follows: 1) For m Evaluation objects, n The evaluation system of evaluation indicators constitutes an indicator matrix, where the evaluation object refers to the evaluation expert in step S401, and the evaluation indicators correspond to the four construction processes before opening, after opening, after closing, and after demolding in step S401. The expression of the indicator matrix is: (1); In the formula, X is the indicator matrix; For the i The first evaluation object j The score value of the indicator, i =1,2,…, m ; j=1,2,…, n ; 2) Standardization: The evaluation model based on the unit engineering construction process has four processes, all of which are positive indicators, and the closer to 1, the better. Therefore, standardization is performed according to formula (2): (2); Where: After standardization i The first evaluation object j The score value of each indicator; Indicates i The first evaluation object j The minimum score value of the indicator. Indicates i The first evaluation object j The maximum score value of an indicator; 3) The variability of the indicator is expressed in the form of standard deviation, and the mathematical expression is: (3); Where: S j For the j The standard deviation of the indicator; For the j The average value of the indicators; in, The calculation formula is: (4); 4) The indicator conflict is expressed in the form of correlation coefficient. The indicator correlation matrix used to calculate the indicator conflict is: (5); Where: R is the correlation coefficient matrix; r ij Indicates evaluation index i and j The correlation coefficient between in, r ij The calculation formula is: (6); Where: After standardization i The first evaluation object k The value of an indicator; For the k The average value of the indicators; (7) ; Where: A j For the j Conflict of evaluation indicators; 5) Amount of information C j Indicates j The role of an evaluation index in the evaluation index system. The larger the value, the greater the weight and the amount of information. C j The calculation formula is: (8) ; Where: C j For the j The role value of each evaluation indicator in the evaluation indicator system; 6) The weight calculation formula is: (9); Where:oh j For the j The objective weight of each indicator; S403. Determine the comprehensive evaluation score and grade: After deducting points according to the deduction standards for each link level in step S3, the evaluation results of each process are obtained. When performing a comprehensive evaluation, the total score calculation formula is: z = oh 1 z 1+ oh 2 z 2+ oh 3 z 3+ oh 4 z 4(10) ; in, oh 1+ oh 2+ oh 3+ oh 4=1; Where: z It is a comprehensive score based on the deduction method; z 1 、z 2 、z 3 、z 4 are the scores before opening, after opening, after closing and after demoulding based on the deduction method; oh 1 、oh 2 、oh 3 、oh 4 are the weight coefficients of the scores before opening, after opening, after closing, and after demolding calculated according to formula (9).

[0011] In a preferred solution, in step S403, the comprehensive evaluation levels of the unit project quality are divided as follows: when z ≥90, the comprehensive evaluation level of the unit project is A; When 70≤ z <90, the comprehensive evaluation level of the unit project is B; When 60≤ z <70, the comprehensive evaluation level of the unit project is C; when z <60, the comprehensive evaluation grade of this unit project is D.

[0012] In the preferred solution, in step S403, when deducting points according to the deducting standards for each link level in step S3 to obtain the evaluation result, if there are reasonable missing items in the evaluation, the evaluation score calculation method for the category of the project after considering the reasonable missing items is: (11); Where: This is the evaluation score of the category of the project after considering reasonable missing items; y ' is the evaluation score of the category of the project in case of reasonable missing items; y The standard score for the category of the project; x i For the i Reasonable missing item standard score; m The number of reasonable missing items.

[0013] In the preferred scheme, in step S5, after all the inspections of the four construction processes of the current casting silo of the unit project are evaluated, when the evaluation level is A, it indicates that the measures for each construction process on site are in place, and enter the next casting silo; when the evaluation level is B, summarize the precautions for subsequent casting silo construction, and enter the next casting silo after approval by the supervisor; when the evaluation level is C, propose rectification measures for subsequent casting silo construction, and enter the next casting silo after approval by the supervisor and designer; when the evaluation level is D, analyze the current casting silo problems together with the owner, design, supervision and scientific research, study and implement remedial measures, propose rectification measures for subsequent casting silo, and enter the next casting silo.

[0014] The present invention also provides a dynamic early warning system for evaluating the construction process of a unit project, comprising an inspection record module, a query record module, a comprehensive evaluation module and a comprehensive management module. The inspection record module is used to record inspection data, and the inspection data includes inspection date, inspection content, inspection photos, videos, feature descriptions, grade classifications and evaluation scores; the query record module is used to record and review query records; the comprehensive evaluation module calculates according to a large-volume concrete crack prevention method based on unit project construction process evaluation and early warning according to any one of claims 1 to 8 to obtain an evaluation grade and an evaluation score; the comprehensive management module includes four parts: part maintenance, execution plan, task creation and user management. Part maintenance is used to add and modify the basic situation of the applied part, the execution plan is used for management personnel to design applicable inspection plans, the task creation is used to issue review tasks for certain abnormal situations or issue temporary tasks after emergencies, and the user management is used to add or delete users.

[0015] The present invention provides a method and system for preventing cracks in large-volume concrete based on evaluation and early warning of the unit engineering construction process, which has the following beneficial effects: 1. Decompose the crack prevention problem of large-volume concrete structures into a series of unit project crack prevention. For each unit project, evaluate and warn the construction process before, after, after and after formwork removal to prevent cracks in each unit project, thereby ensuring that no harmful cracks occur in the entire large-volume concrete structure.

[0016] 2. A “four-in-one” unit engineering quality evaluation system and evaluation standard was proposed, including before opening, after opening, after closing and after demolding.

[0017] 3. The crack prevention of large-volume concrete is decomposed into the crack prevention of each unit project, and then a large-volume concrete crack prevention mode based on the dynamic control of the unit project construction process and the comprehensive evaluation and control of the unit project is proposed to solve the problem of unreliable simulation calculation of temperature field and temperature stress field caused by the lack of thermal and mechanical properties parameters of concrete, and overcome the problem of inadequate implementation of on-site construction measures and design measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 A technical route diagram of mass concrete crack prevention for evaluating and warning the unit engineering construction process of the present invention; Figure 2 It is the unit project construction process evaluation system; Figure 3 Evaluate the dynamic early warning and control process for the unit project construction process; Figure 4 Functional module diagram of dynamic early warning system for unit project construction process evaluation; Figure 5 It is the interface of dynamic early warning system for unit project quality evaluation; Figure 6 It is the evaluation result interface of the unit project quality evaluation dynamic early warning system. DETAILED DESCRIPTION

[0019] A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process, such as Figure 1 As shown, the following steps are included: S1. Establish a unit project construction process evaluation system.

[0020] The inspection items of the concrete water engineering construction process were sorted out, and based on the principles of "few but good, detectable, evaluable and comprehensive", an evaluation system for the unit project before opening, after opening, after closing and after demolding was established, such as Figure 2 As shown, the inspection before opening includes the appearance, location and size, material quality, and mechanical equipment; the inspection after opening includes the ambient temperature, concrete temperature, and construction quality; the inspection after closing includes the insulation condition in the low temperature season or the maintenance condition in the high temperature season, the water supply condition, and the concrete temperature condition; the inspection after demolding includes the insulation condition in the low temperature season or the maintenance condition in the high temperature season, and the concrete temperature condition.

[0021] S2. Divide the construction process evaluation level standards of unit projects.

[0022] With reference to the water engineering safety assessment guidelines, existing reported literature and engineering experience, as well as consulting experts in design, construction, supervision and scientific research, the construction process of the concrete water engineering unit project was divided into grade standards using a four-level evaluation standard, from best to worst, they are divided into grade a, grade b, grade c and grade d. The evaluation grade standards before opening, after opening, after closing and after demolding are shown in Tables 1 to 4.

[0023]

[0024]

[0025]

[0026]

[0027] S3. Formulate deduction standards for unit project construction process quality evaluation based on the deduction method.

[0028] Referring to the "Standardized Management Evaluation Standards for Large and Medium-sized Reservoir Projects" issued by the Ministry of Water Resources in March 2022, 100 points were assigned to each link of the unit project quality evaluation, and then allocated to each inspection item, inspection content and each evaluation level. Deduction points are used to formulate the quality evaluation status deduction standards for large-volume concrete unit projects. The deduction standards are shown in Tables 5 to 8.

[0029]

[0030]

[0031]

[0032]

[0033] S4. Comprehensive evaluation calculation and grade assessment.

[0034] The following steps are involved: S401. Due to the different importance of the four construction processes before warehouse opening, after warehouse opening, after warehouse closing, and after formwork removal, different weights need to be assigned. Invite a number of evaluation experts in concrete temperature control and crack prevention in the fields of design, construction, supervision, and scientific research to score the importance of the four construction processes before warehouse opening, after warehouse opening, after warehouse closing, and after formwork removal.

[0035] S402. Considering that the experts' ratings of the above four construction processes are subjective, the Critic method is introduced to obtain reasonable weights based on the experts' ratings of the importance of the four construction processes.

[0036] The Critic method is used to weight the four processes, and the calculation process is as follows: 1) Form Evaluation objects, n The evaluation system of evaluation indicators constitutes an indicator matrix, where the evaluation object refers to the evaluation expert in step S401, and the evaluation indicators correspond to the four construction processes before opening, after opening, after closing, and after demolding in step S401. The expression of the indicator matrix is: (1); In the formula, X is the indicator matrix; For the i The first evaluation object j The score value of the indicator, i =1,2,…, m ; j=1,2,…, n ; 2) Standardization: The evaluation model based on the unit engineering construction process has four processes, all of which are positive indicators, and the closer to 1, the better. Therefore, standardization is performed according to formula (2): (2); Where: After standardization i The first evaluation object j The score value of each indicator; Indicates i The first evaluation object j The minimum score value of the indicator. Indicates i The first evaluation object j The maximum score value of an indicator; 3) The variability of the indicator is expressed in the form of standard deviation, and the mathematical expression is: (3); Where: S j For the j The standard deviation of the indicator; For the j The average value of the indicators; in, The calculation formula is: (4); 4) The indicator conflict is expressed in the form of correlation coefficient. The indicator correlation matrix used to calculate the indicator conflict is: (5); Where: R is the correlation coefficient matrix; r ij Indicates evaluation index i andj The correlation coefficient between in, r ij The calculation formula is: (6); Where: After standardization i The first evaluation object k The value of an indicator; For the k The average value of the indicators; (7) ; Where: A j For the j Conflict of evaluation indicators; 5) Amount of information C j Indicates j The role of an evaluation index in the evaluation index system. The larger the value, the greater the weight and the amount of information. C j The calculation formula is: (8) ; Where: C j For the j The role value of each evaluation indicator in the evaluation indicator system; 6) The weight calculation formula is: (9); Where: oh j For the j The objective weight of each indicator; S403. Determine the comprehensive evaluation score and grade: After deducting points according to the deducting standards for each link level in step S3, the evaluation results of each process are obtained.

[0037] When conducting a comprehensive evaluation, the total score calculation formula is: z = oh 1 z 1+ oh 2 z 2+ oh 3 z 3+ oh 4 z 4(10) ; in, oh 1+ oh 2+ oh 3+ oh 4=1; Where: z It is a comprehensive score based on the deduction method; z 1 、z 2 、z 3 、z 4 are the scores before opening, after opening, after closing and after demoulding based on the deduction method; oh 1 、oh 2 、oh 3 、oh 4 are the weight coefficients of the scores before opening, after opening, after closing, and after demolding calculated according to formula (9).

[0038] In actual evaluation, there are often incomplete inspection items. Therefore, if there are reasonable missing items in the evaluation, the evaluation score of the category of the project after considering the reasonable missing items is calculated as follows: (11); Where: This is the evaluation score of the category of the project after considering reasonable missing items; y ' is the evaluation score of the category of the project in case of reasonable missing items; y The standard score for the category of the project; x i For the i Reasonable missing item standard score; m The number of reasonable missing items.

[0039] The comprehensive evaluation levels of unit project quality are divided as follows: when z ≥90, the comprehensive evaluation level of the unit project is A; When 70≤ z <90, the comprehensive evaluation level of the unit project is B; When 60≤ z <70, the comprehensive evaluation level of the unit project is C; when z <60, the comprehensive evaluation grade of this unit project is D.

[0040] S5. Dynamic early warning and control of on-site measures based on unit project construction process evaluation.

[0041] like Figure 3 As shown, the inspection items before opening, after opening, after closing and after demolding are evaluated in sequence according to the construction process. For inspection items evaluated as level C or level D, early warning is issued, requiring timely adjustment of on-site measures.

[0042] After all the inspections and evaluations of the four construction processes of the current casting silo of the unit project are completed, a comprehensive evaluation is conducted using the deduction method. When the evaluation grade is A, it indicates that the measures for each construction process on site are in place, and the next casting silo is entered; when the evaluation grade is B, the precautions for subsequent casting silo construction are summarized, and after approval by the supervisor, the next casting silo is entered; when the evaluation grade is C, rectification measures for subsequent casting silo construction are proposed, and after approval by the supervisor and designer, the next casting silo is entered; when the evaluation grade is D, together with the owner, designer, supervisor and scientific research, the current casting silo problems are analyzed, remedial measures are studied and implemented, rectification measures for subsequent casting silo are proposed, and the next casting silo is entered.

[0043] A dynamic early warning system for the evaluation of the construction process of a unit project is developed using MySql as the database of the system and Java1.8 language. The system uses a lightweight Spring-Boot framework in terms of technology, which is simple to develop, stable and smooth, reduces the complexity of business object replacement, and supports multi-user and high concurrent access. The framework implements the MVC model with a clear hierarchical structure; MySQL is a relational database management system with small size, fast speed and low total cost of ownership. System operating hardware and software environment: CPU 1.2G and above, 1G memory, hard disk 80G or above; system operating system: Windows7, Windows10, Windows11.

[0044] like Figure 4 As shown, the system includes an inspection record module, a query record module, a comprehensive evaluation module and a comprehensive management module.

[0045] The inspection record module is used to record inspection data, which includes inspection date, inspection content, inspection photos, videos, feature descriptions, grade classifications and assessment scores.

[0046] The query record module is used to record and review query records. By selecting the corresponding inspection date or inspection period to query the records, the reviewer can query the inspection results of the current time and conduct an audit. If the audit is passed, the inspection record of the current time can be exported.

[0047] The comprehensive evaluation module uses the mass concrete crack prevention method based on the unit engineering construction process evaluation and early warning to calculate and obtain the evaluation grade and evaluation score. For a certain inspection information system, the evaluation grade and evaluation score are calculated using the set evaluation method, and all abnormal parts are summarized, and corresponding suggestions are submitted according to the final evaluation results.

[0048] The comprehensive management module includes four parts: site maintenance, execution plan, task creation and user management. Site maintenance is used to add and modify the basic information of the applied site. The execution plan is used for managers to design applicable inspection plans. Task creation is used to issue review tasks for certain abnormal situations or issue temporary tasks after emergencies. User management is used to add or delete users.

[0049] Example Analysis A large ship lock project is a Class II ship lock, divided into 12 lock chambers. The bottom plate of each lock chamber is divided into 3 blocks, namely the middle, south and north blocks, which are cast as a unit project. The side walls are cast in 3 casting bins, that is, each lock chamber is divided into 4 unit projects. During the construction process, the unit project construction process evaluation and early warning method proposed in this patent is used to prevent cracking. The following is an explanation of the evaluation of the unit project construction process of the bottom plate of the 10# lock chamber of the ship lock. The bottom plate was opened at 9:30 pm on January 20, 2022 and closed at 2 am on January 22, 2022. The inspection and evaluation results of each link are as follows:

[0050]

[0051]

[0052]

[0053] Four experts with relevant engineering experience were invited to score the four links before opening, after opening, after closing and after demolding. The results are shown in Table 13. The weight coefficients of the four links in the overall evaluation of unit project quality were calculated by combining formulas (1) to (9). The calculation results are shown in Table 14.

[0054]

[0055]

[0056] Combining formula (10), we can get: z =0.2138×95+0.2984×96+0.2596×91+0.2282×78=90.38 points Comprehensive evaluation z >90, so the comprehensive evaluation grade of this unit project is A. This shows that the current construction process measures of the casting silo are basically reasonable. However, the following problems can be seen from the scoring results: (1) After closing, the temperature difference between the inlet and outlet water is too large. It is recommended to increase the water flow rate and appropriately increase the water temperature after closing. (2) After demolding, there is a large temperature difference between the inside and outside of the concrete. It is recommended to strengthen the surface insulation.

[0057] The implementation of the dynamic early warning system for unit project construction process evaluation is as follows: Figure 5 and 6 shown.

[0058] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process, characterized in that: The following steps are involved: S1. Establish a unit project construction process evaluation system; S2. Classification of unit project construction process evaluation standards; S3. Formulate deduction standards for unit project construction process quality evaluation based on the deduction method; S4, comprehensive evaluation calculation and grade assessment; S5. Dynamic early warning and control of on-site measures based on unit project construction process evaluation.

2. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 1, characterized in that: In step S1, the unit project construction process evaluation system includes evaluation systems for the unit project before opening, after opening, after closing and after demolding, wherein the inspection before opening includes appearance, location and size, material quality, and mechanical equipment; the inspection after opening includes ambient temperature, concrete temperature, and construction quality; the inspection after closing includes insulation conditions in low temperature seasons or maintenance conditions in high temperature seasons, water flow conditions, and concrete temperature conditions; the inspection after demolding includes insulation conditions in low temperature seasons or maintenance conditions in high temperature seasons and concrete temperature conditions.

3. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 1, characterized in that: In step S2, the construction process of the concrete water engineering unit project is divided into grades according to a 4-grade evaluation standard, and the evaluation grades before warehouse opening, after warehouse opening, after warehouse closing and after formwork removal are divided into grades A, B, C and D from best to worst.

4. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 1, characterized in that: In step S3, 100 points are assigned to each link of the unit engineering quality evaluation, and then allocated to each inspection item, inspection content and each evaluation level deduction score, thereby formulating the deduction standard for the quality evaluation of large-volume concrete unit engineering.

5. The method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 1 is characterized in that: In step S4, the comprehensive evaluation calculation and grade judgment include the following steps: S401. Invite evaluation experts to rate the importance of the four construction processes: before warehouse opening, after warehouse opening, after warehouse closing, and after formwork removal; S402. Use the Critic method to assign weights to the four construction processes. The calculation process is as follows: 1) For m Evaluation objects, n The evaluation system of evaluation indicators constitutes an indicator matrix, where the evaluation object refers to the evaluation expert in step S401, and the evaluation indicators correspond to the four construction processes before opening, after opening, after closing, and after demolding in step S401. The expression of the indicator matrix is: ；(1)； In the formula, X is the indicator matrix; For the i The first evaluation object j The score value of the indicator, i =1,2,…, m ; j=1,2,…, n ; 2) Standardization: The evaluation model based on the unit engineering construction process has four processes, all of which are positive indicators, and the closer to 1, the better. Therefore, standardization is performed according to formula (2): ；(2)； Where: After standardization i The first evaluation object j The score value of each indicator; Indicates i The first evaluation object j The minimum score value of the indicator. Indicates i The first evaluation object j The maximum score value of an indicator; 3) The variability of the indicator is expressed in the form of standard deviation, and the mathematical expression is: ；(3)； Where: S j For the j The standard deviation of the indicator; For the j The average value of the indicators; in, The calculation formula is: ；(4)； 4) The indicator conflict is expressed in the form of correlation coefficient. The indicator correlation matrix used to calculate the indicator conflict is: ；(5)； Where: R is the correlation coefficient matrix; r ij Indicates evaluation index i and j The correlation coefficient between in, r ij The calculation formula is: ；(6)； Where: After standardization i The first evaluation object k The value of an indicator; For the k The average value of the indicators; ；(7) ； Where: A j For the j Conflict of evaluation indicators; 5) Amount of information C j Indicates j The role of an evaluation index in the evaluation index system. The larger the value, the greater the weight and the amount of information. C j The calculation formula is: ；(8) ； Where: C j For the j The role value of each evaluation indicator in the evaluation indicator system; 6) The weight calculation formula is: ；(9)； Where: ω j For the j The objective weight of each indicator; S403. Determine the comprehensive evaluation score and grade: After deducting points according to the deduction standards for each link level in step S3, the evaluation results of each process are obtained. When performing a comprehensive evaluation, the total score calculation formula is: z = ω 1 z 1+ ω 2 z 2+ ω 3 z 3+ ω 4 z 4；(10) ； in, ω 1+ ω 2+ ω 3+ ω 4=1; Where: z It is a comprehensive score based on the deduction method; z 1 、z 2 、z 3 、z 4 are the scores before opening, after opening, after closing and after demoulding based on the deduction method; ω 1 ,ω 2 ,ω 3 ,ω 4 are the weight coefficients of the scores before opening, after opening, after closing, and after demolding calculated according to formula (9).

6. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 5, characterized in that: In step S403, the comprehensive evaluation levels of the unit project quality are divided as follows: when z ≥90, the comprehensive evaluation level of the unit project is A; When 70≤ z <90, the comprehensive evaluation level of the unit project is B; When 60≤ z <70, the comprehensive evaluation level of the unit project is C; when z <60, the comprehensive evaluation grade of this unit project is D.

7. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 4, characterized in that: In step S403, when the evaluation result is obtained by deducting points according to the deduction standards for each link level in step S3, if there are reasonable missing items in the evaluation, the evaluation score calculation method for the category of the project after considering the reasonable missing items is: ；(11)； Where: This is the evaluation score of the category of the project after considering reasonable missing items; y ' is the evaluation score of the category of the project in case of reasonable missing items; y The standard score for the category of the project; x i For the i Reasonable missing item standard score; m The number of reasonable missing items.

8. A method for preventing cracking of large-volume concrete based on evaluation and early warning of unit engineering construction process according to claim 6, characterized in that: In the step S5, after all the inspections of the four construction processes of the current casting bin of the unit project are evaluated, when the evaluation level is A, it indicates that the measures for each construction process on site are in place, and the next casting bin is entered; when the evaluation level is B, the precautions for the subsequent casting bin construction are summarized, and after the approval of the supervisor, the next casting bin is entered; when the evaluation level is C, the subsequent casting bin construction rectification measures are proposed, and after the approval of the supervisor and the designer, the next casting bin is entered; when the evaluation level is D, together with the owner, design, supervision and scientific research, the current casting bin problems are analyzed, remedial measures are studied and implemented, and rectification measures for the subsequent casting bin are proposed, and the next casting bin is entered.

9. A dynamic early warning system for evaluating the construction process of a unit project, characterized in that: It includes an inspection record module, a query record module, a comprehensive evaluation module and a comprehensive management module. The inspection record module is used to record inspection data, including inspection date, inspection content, inspection photos, videos, feature descriptions, grade classifications and assessment scores; the query record module is used to record and review query records; the comprehensive evaluation module calculates a large-volume concrete crack prevention method based on unit engineering construction process evaluation and early warning according to any one of claims 1 to 8 to obtain an evaluation grade and an evaluation score; the comprehensive management module includes four parts: site maintenance, execution plan, task creation and user management. Site maintenance is used to add and modify the basic situation of the applied site, the execution plan is used for management personnel to design applicable inspection plans, the task creation is used to issue review tasks for certain abnormal situations or issue temporary tasks after emergencies, and the user management is used to add or delete users.

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