Underground overpass main body side wall structure concrete anti-cracking waterproof construction method

Abstract

The application provides a kind of underground interchange main body side wall structure concrete crack resistance waterproof construction method, it is related to underground engineering concrete construction technical field, the application is by dividing side wall into multiple sub-regions, obtains the geometric curvature of each sub-region, structural constraint, cross section variation, temperature action, shrinkage strain, load tensile stress, joint adjacent and waterproof weak parameter;Based on the first six parameters, calculate the crack resistance risk value, combined with the last two parameters to calculate the waterproof failure risk value, and determine the comprehensive protection requirement value accordingly;According to the comprehensive protection requirement value, the sub-regions are classified, and the target areas that need to be strengthened are identified;Different regions are respectively used C40 concrete with conventional or hybrid fiber optimal ratio, and the pouring segment length is dynamically determined according to the maximum crack resistance risk value, to realize differentiated crack resistance waterproof construction.

Description

Technical Field

[0001] This invention relates to the field of underground engineering concrete construction technology, specifically a method for crack-resistant and waterproof construction of the main side wall structure of an underground interchange. Background Technology

[0002] In large-scale underground engineering projects such as underground interchanges, the main sidewalls, as key components bearing earth pressure, water pressure, and structural weight, directly affect the long-term safety and durability of the project due to the crack resistance and waterproofing performance of their concrete structures. Because underground interchange sidewalls are typically long, geometrically complex, and subject to varying constraints, they are prone to tensile stress concentration during concrete hardening due to factors such as temperature gradients, autogenous shrinkage, drying shrinkage, and external loads, which can induce cracks. Once cracks penetrate or form connecting channels, they significantly weaken the structure's self-waterproofing capacity, leading to leakage and even steel corrosion, severely impacting the structure's service life. Therefore, effectively controlling concrete cracking in sidewalls and ensuring waterproofing reliability has always been a key technical challenge in the field of underground engineering.

[0003] To address the aforementioned issues, existing technologies primarily employ methods such as segmented casting, adding expansion agents or fibers, installing temperature-controlled water pipes, and optimizing curing procedures to control cracking. The prior art disclosed in CN112195979A proposes dividing the sidewall into alternating segments of 8-10m and 2-5m, pouring concrete mixed with different expansion agents in different segments, and combining temperature-controlled water pipes and online monitoring to achieve crack control based on theoretical stress. The prior art disclosed in CN112160443A uses temperature-controlled templates and a measured stress feedback mechanism under summer construction conditions to adjust the internal tensile stress of the concrete to suppress cracking. The prior art disclosed in CN113774957A, targeting the main structure of open-cut cast-in-place tunnels, sets crack resistance control indicators from two dimensions: temperature and shrinkage deformation, forming a customized complete technical solution. Furthermore, the prior art disclosed in CN110004975A ​​constructs a self-waterproofing system for residential underground engineering through segment length design, crack-resistant agent selection, mix ratio optimization, and full-process temperature-controlled curing. These methods, to a certain extent, alleviate the risk of concrete cracking and improve waterproofing performance.

[0004] However, the aforementioned existing technologies generally share a common flaw: their homogeneous or coarse-grained zoning design approach fails to fully consider the multi-source heterogeneity of underground interchange sidewalls in space. Specifically, different parts of the sidewall exhibit significant differences in geometric curvature, abrupt changes in cross-section, structural constraint strength, thermal stress distribution, location of adjacent construction joints or expansion joints, and groundwater permeability sensitivity. Existing methods typically treat these differences uniformly with fixed lengths, lacking a refined identification and differentiated response mechanism for high-risk local areas. This results in high-risk areas remaining prone to cracking and leakage due to insufficient protection, while low-risk areas are over-allocated with materials and process resources, leading to cost waste and reduced construction efficiency. More importantly, existing technologies have not yet established a comprehensive protection demand assessment system that can integrate multi-dimensional parameters such as geometry, mechanics, environment, and structure, and couple and quantify them into a gradeable, locatable system that can directly drive concrete mix design and pouring process decisions. Consequently, it is difficult to achieve the goal of on-demand protection and precise crack resistance and waterproofing.

[0005] Furthermore, in high-risk areas such as the high-curvature sections and the connection between the bottom and top slabs of underground interchanges, single fiber reinforcement technology is insufficient to effectively offset the temperature stress generated by hydration heat and the tensile stress generated by soil and water loads, and the risk of macroscopic cracking still exists. Although there are existing studies on applying prestressing to concrete crack resistance, it has not yet been integrated with the risk classification assessment system, making it impossible to achieve differentiated and precise prestressing. This results in the problem of "insufficient prestressing in high-risk areas and excessive reinforcement in low-risk areas," failing to fully leverage the synergistic crack resistance effect of prestressing and hybrid fibers.

[0006] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method for constructing crack-resistant and waterproof concrete for the main side wall structure of underground interchanges, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A method for constructing crack-resistant and waterproof concrete sidewall structures for underground interchanges, comprising the following steps: S1: Divide the main sidewall of the underground interchange into multiple sub-regions to be evaluated; for each sub-region to be evaluated, obtain the geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, load tensile stress parameters, joint proximity parameters, and waterproofing weakness parameters of that sub-region. S2: Based on geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, and load tensile stress parameters, calculate the crack resistance risk value of each sub-region to be evaluated; S3: Calculate the waterproofing failure risk value of each sub-region to be evaluated based on the crack resistance risk value, waterproofing weakness parameter, and joint proximity parameter of each sub-region to be evaluated; S4: Based on the crack resistance risk value and waterproofing failure risk value of each sub-region to be evaluated, determine the comprehensive protection requirement value of each sub-region to be evaluated; S5: Based on the comprehensive protection requirements of each sub-region to be evaluated, the sub-regions to be evaluated are classified, and the sub-regions to be evaluated that reach the preset level are identified as target sub-regions that need to be strengthened in terms of crack resistance and waterproof protection, while other sub-regions are classified as non-target sub-regions. S6: Prepare hybrid fiber crack-resistant concrete, determine the composition of concrete raw materials and fiber mixing parameters, obtain the conventional concrete mix ratio required for non-target sub-regions and the optimal concrete mix ratio corresponding to the target sub-regions that need enhanced crack resistance and waterproof protection, determine the length of the side wall pouring segments, and pour each sub-region in layers.

[0009] Furthermore, the division of the main sidewall of the underground interchange into multiple sub-areas to be evaluated is specifically as follows: the sub-areas to be evaluated are divided according to the rule of basic grid and sensitive area densification. The basic segmentation unit is 2m along the longitudinal direction of the underground interchange sidewall line, and the basic layering unit is 1.5m along the vertical direction of the sidewall, forming a 2m×1.5m basic evaluation grid. Each independent grid is one sub-area to be evaluated.

[0010] Furthermore, for each sub-region to be evaluated, geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, tensile stress parameters, and joint proximity parameters are obtained by constructing a BIM model, conducting on-site surveys, and implementing a construction plan. Among these, the geometric curvature parameters are directly extracted from the sub-region in the BIM model. Average radius of curvature at the centerline Then the geometric curvature parameter For a straight line segment, Consider it as infinitely large. Pick Structural constraint parameters are calculated by measuring the average thickness d of the sub-region and its rate of change along the length direction. The cross-sectional variation parameter is defined as follows: If there is no change in cross-section, Set to 0; this parameter is dimensionless. Furthermore, the geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, load tensile stress parameters, and joint proximity parameters are subjected to extreme value normalization processing, converting them into dimensionless indices positively correlated with crack resistance risk within the interval [0,1]. Then, the crack resistance risk value of each sub-region to be evaluated is calculated using a weighted coupling formula, with a value range of [0,1]. The weighted coupling formula is as follows: in, Sub-region to be evaluated The crack resistance risk value, The normalized sub-region to be evaluated The geometric curvature parameters, For the normalized sub-region to be evaluated Structural constraint parameters, These are the normalized cross-sectional variation parameters. Sub-region to be evaluated The maximum principal tensile stress under the load, The preset standard value for the axial tensile strength of concrete. Sub-region to be evaluated Maximum internal and external temperature difference For reference temperature difference, Sub-region to be evaluated Shrinkage strain value, The preset reference shrinkage strain, These are the weighting coefficients for each item in the calculation of crack resistance risk value, and they satisfy... ; This is the index of the sub-region to be evaluated.

[0011] Further, in step S3, the waterproofing weakness parameter is first subjected to extreme value normalization processing, converting it into a dimensionless index positively correlated with the waterproofing failure risk in the interval [0,1]. The normalized joint proximity parameter reuses the calculation result of step S2; then, the waterproofing failure risk value of each sub-region to be evaluated is calculated through a coupling formula, with a value range of [0,1]. The coupling formula is: In the formula: Sub-region to be evaluated The risk value of waterproof failure, Sub-region to be evaluated The weakest parameter in waterproofing, Sub-region to be evaluated Normalized seam proximity parameters, These are the weighting coefficients for each item in the calculation of the waterproofing failure risk value, and they satisfy... 1.

[0012] Further, in step S4, the comprehensive protection requirement value for each sub-region to be evaluated is determined by: calculating and normalizing to the [0,1] interval using the Euclidean norm, as shown in the formula: in, Sub-region to be evaluated The comprehensive protection requirements.

[0013] Furthermore, the sub-regions to be evaluated are classified into four protection levels based on the comprehensive protection requirement value: Level I: Level II: Level III: Level IV: <0.3; The preset protection enhancement trigger level is Level II or above, which means all comprehensive protection requirements are set to... The sub-areas to be evaluated with a value ≥0.6 are identified as target sub-areas requiring enhanced crack resistance and waterproofing protection.

[0014] Furthermore, hybrid fiber-reinforced crack-resistant concrete is prepared. The conventional and optimal proportion concrete materials use the same standard raw materials, and only the dosage of mineral admixtures, fibers, and additives is adjusted to ensure that the design strength of concrete with different proportions is C40.

[0015] Furthermore, determining the length of the sidewall pouring segments specifically involves: setting a lower threshold for the sidewall pouring segment length; calculating the sidewall pouring segment length based on the maximum crack resistance risk value of all sub-regions within the segment. Binding, the calculation formula is: in, The length of the side wall pouring segment is specified. A minimum threshold for the pre-set sidewall pouring segment length is established; the ends of all pouring segments are set at... Within the IV-level sub-region with a value ≤0.3.

[0016] Furthermore, regarding the comprehensive protection requirements... For Class I special-grade protection sub-areas with a strength ≥0.8, low-relaxation prestressed steel strands are arranged inside the steel mesh, with two rows of prestressing tendons on the same horizontal plane and a vertical spacing of 400mm. Prestressing is applied using either a cooling method or pre-tensioning method, with the tension control stress taken as 0.6 times the standard value of the steel strand strength. For sharp curves with a radius of curvature greater than 40m, the prestressing tendons are arranged along the tangent of the curve, with the spacing increased to 300mm vertically at the point of maximum curvature. The prestressing and hybrid fibers form a macroscopic and microscopic synergistic crack-resistant system: the prestressing bears the overall tensile stress, offsetting temperature deformation and load deformation; the fibers bridge microscopic cracks, absorb deformation energy, and prevent crack propagation.

[0017] Compared with existing technologies, the beneficial effects of this invention are: it achieves a quantitative decoupling and coupled synergistic assessment of sidewall crack resistance and waterproofing risk. This is achieved by introducing seven types of multi-dimensional structure-environment-material parameters, including geometric curvature parameters, structural constraint parameters, and cross-sectional change parameters, and establishing a system based on crack resistance risk... Waterproofing failure risk as the core cause The model overcomes the shortcomings of traditional methods that prioritize waterproofing over crack resistance or fail to adequately assess both crack resistance and waterproofing. Based on comparative data from a city's underground interchange project, the accuracy of waterproofing failure prediction is improved. Furthermore, this solution achieves a closed-loop mapping from risk values ​​to construction actions. (Comprehensive protection requirement value) After Euclidean norm normalization, it directly drives the classification of protection levels and the identification of target areas, supporting differentiated material ratios, adaptive pouring segments, and precise vibration control. Compared with the uniform C40+ single-fiber scheme, the average crack width in high-risk areas is reduced. At the same time, it significantly improves resource utilization efficiency and construction controllability. Redundant steel fibers and high-volume fly ash are eliminated in Level III and IV areas, reducing the cost per cubic meter of concrete and avoiding segregation caused by excessive vibration in low-risk areas. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 This is a table showing the risk value calculation results for an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Example: Please see Figures 1-2 The present invention provides a technical solution: A method for constructing crack-resistant and waterproof concrete sidewall structures for underground interchanges, comprising the following steps: S1: Divide the main sidewall of the underground interchange into multiple sub-regions to be evaluated; for each sub-region to be evaluated, obtain the geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, load tensile stress parameters, joint proximity parameters, and waterproofing weakness parameters of that sub-region. In this embodiment, the main line sidewall of an underground interchange in a core urban area is used as an example. This sidewall is 120m long and 9m high, comprising a 30m straight section, a 60m gentle curve section with a curvature radius of 60-100m, and a 30m sharp curve section with a curvature radius of 33-40m. The geological conditions include silty clay and water-rich sand layers. The design service life is 100 years, the concrete strength grade is C40, and the waterproofing grade is Class I. The main line sidewall of the underground interchange is divided into multiple sub-areas to be evaluated. Specifically, the sub-areas to be evaluated are divided using a basic grid and a sensitive area densification rule. Along the longitudinal direction of the underground interchange sidewall, a basic segment unit of 2m is used, and along the vertical direction of the sidewall, a basic layer unit of 1.5m is used, forming a 2m × 1.5m basic evaluation grid. Each independent grid is one sub-area to be evaluated. Identify sensitive areas: sharp curves with a radius of curvature of less than 50m, variable cross-sections with a cross-sectional change rate of more than 10%, the area within 2m around construction joints, and water-rich sandy areas. Refine the longitudinal grid of these areas to 1m to form a 1m×1.5m densified evaluation grid.

[0022] Traditional construction methods typically assess sidewalls as a whole in 10-20m sections, or only treat obvious cross-section changes and joint areas separately, failing to identify risk differences in small local areas. This leads to missed assessments of high-risk points and over-protection of low-risk areas. This solution uses a regular grid-based approach with denser sensitive areas to decompose the sidewalls into standard 2m×1.5m assessment units, achieving precise spatial positioning of risks. Simultaneously, the system collects core influencing parameters, comprehensively covering all crack-resistant and waterproofing-related factors such as geometry, structure, temperature, load, and waterproofing, providing a complete data foundation for subsequent risk calculations.

[0023] In this embodiment, for each sub-region to be evaluated, geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, tensile stress parameters, and joint proximity parameters are obtained by constructing a BIM model, conducting on-site surveys, and implementing a construction plan. The geometric curvature parameters are directly extracted from the sub-region within the BIM model. Average radius of curvature at the centerline Then the geometric curvature parameter For a straight line segment, Consider it as infinitely large. Pick After the concrete of the curved sidewall is poured, additional circumferential tensile stress will be generated due to the curvature. The smaller the radius of curvature, the greater the additional tensile stress and the higher the risk of cracking. The structural constraint parameters are calculated by measuring the average thickness d of the sub-region and its rate of change along the length direction. The cross-sectional variation parameter is defined as follows: If there is no change in cross-section, Set to 0; this parameter is dimensionless; changes in cross-sectional thickness lead to stress concentration, and the greater the rate of change, the more pronounced the stress concentration; simultaneously, the greater the cross-sectional thickness, the more difficult it is to dissipate the heat of hydration, resulting in higher temperature stress. Using the product of thickness and rate of change can simultaneously reflect the influence of these two factors.

[0024] S2: Based on geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, and load tensile stress parameters, calculate the crack resistance risk value of each sub-region to be evaluated; In this embodiment, the geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, load tensile stress parameters, and joint proximity parameters are subjected to extreme value normalization processing, and converted into dimensionless indices positively correlated with crack resistance risk in the interval [0,1]. The normalization formula is: In the formula, These are the normalized parameter values. These are the original parameter values. These are the maximum and minimum values ​​of this parameter for all sub-regions to be evaluated, respectively.

[0025] The crack resistance risk value of each sub-region to be evaluated is then calculated using a weighted coupling formula, with the value ranging from [0,1]. The weighted coupling formula is as follows: in, Sub-region to be evaluated The crack resistance risk value, The normalized sub-region to be evaluated The geometric curvature parameters, For the normalized sub-region to be evaluated Structural constraint parameters, These are the normalized cross-sectional variation parameters. Sub-region to be evaluated The maximum principal tensile stress under the load, The preset standard value for the axial tensile strength of concrete. Sub-region to be evaluated Maximum internal and external temperature difference For reference temperature difference, Sub-region to be evaluated Shrinkage strain value, The preset reference shrinkage strain, These are the weighting coefficients for each item in the calculation of crack resistance risk value, and they satisfy... ; This is the index of the sub-region to be evaluated. In this embodiment, Strictly adhere to the principle that the degree of influence is positively correlated with the weight; The highest weight is given because the heat of hydration temperature stress is the primary factor in cracking of underground large-volume concrete, accounting for 35%-40% of the causes of cracks. The large thickness of the sidewalls makes it difficult for internal heat to dissipate, and the tensile stress generated by the temperature difference between the inside and outside often exceeds the tensile strength of the concrete. and Secondly, the corresponding structural constraints account for 25%-30% of crack formation, with the crack rate in the strongly constrained zone being 4-6 times that of the free end, and the long-term soil and water load accounts for 20%-25% of crack formation. The shrinkage strain corresponding to 60 days of concrete accounts for 10%-15% of the causes of cracks, mainly causing early surface cracks. and These correspond to geometric curvature and cross-sectional changes, each accounting for 5%-10%, with significant impact only in local high-risk areas such as sharp curves and variable cross-section sections. This weighting system has been validated in engineering, demonstrating high accuracy in crack prediction. The sensitivity ranking in orthogonal experiments is completely consistent with the weights, while a fine-tuning range of ±0.05 is reserved to adapt to different geological and construction conditions. This embodiment selects 10 typical locations on the sidewalls of underground interchanges for evaluation. The original data collection and calculation parameters are shown in Table 1 below: Table 1: Original Parameters of Experimental Samples This table presents the six normalized core input parameters and the final crack resistance risk calculation results for 10 experimental samples. The samples cover all structural forms from the free end of a straight section to a double-constrained section of a sharp curve, and all geological conditions from dry soil to highly water-rich layers. All parameters have been normalized to dimensionless indices in the [0,1] interval, eliminating dimensional differences. The crack resistance risk value increases from a minimum of 0 to a theoretical maximum of 1.0, showing a clear gradient distribution and a significant positive correlation with geometric curvature, structural constraint strength, and geological conditions. This table intuitively demonstrates the contribution of each factor to the crack resistance risk and serves as the core foundational data for subsequent waterproofing failure risk calculations and protection level classifications.

[0026] Traditional crack risk assessments typically consider only a single factor such as temperature stress or shrinkage strain, or rely on simple empirical judgments. They cannot quantify the comprehensive crack risk under the combined effects of multiple factors, resulting in assessments that are highly subjective and have low accuracy.

[0027] This solution employs a multi-parameter weighted coupling model, incorporating six core crack resistance influencing factors—geometric curvature, structural constraints, cross-sectional changes, tensile stress, temperature stress, and shrinkage strain—into a unified calculation framework. Weighting coefficients reflect the degree of influence of different factors, enabling a quantitative assessment of crack resistance risk. This is the core calculation step of the entire technical solution; accurate crack resistance risk values ​​are not only the foundation for subsequent waterproofing failure risk calculations but also a crucial basis for determining concrete mix proportions and pouring segment lengths.

[0028] S3: Calculate the waterproofing failure risk value of each sub-region to be evaluated based on the crack resistance risk value, waterproofing weakness parameter, and joint proximity parameter of each sub-region to be evaluated; In this embodiment, the waterproofing weakness parameter is first subjected to extreme value normalization processing, which is the same as that of extreme value S2, and converted into a dimensionless index positively correlated with the waterproofing failure risk in the interval [0,1]. The normalized joint proximity parameter reuses the calculation result of step S2; then, the waterproofing failure risk value of each sub-region to be evaluated is calculated through a coupling formula, with the value range being [0,1]. The coupling formula is as follows: In the formula: Sub-region to be evaluated The risk value of waterproof failure, Sub-region to be evaluated The weakest parameter in waterproofing, Sub-region to be evaluated Normalized seam proximity parameters, These are the weighting coefficients for each item in the calculation of the waterproofing failure risk value, and they satisfy... 1. In this embodiment, There are three main reasons for the failure of waterproofing in concrete structures: first, cracks in the concrete itself create seepage channels; second, high groundwater pressure and good soil permeability make leakage easy; and third, construction joints are weak points in waterproofing and are prone to leakage. Therefore, the formula incorporates these three core factors, including the crack resistance risk value. The one with the highest weight: This reflects the core idea that crack resistance is the foundation of waterproofing. According to statistics on underground engineering leakage cases, approximately 70% of leaks are caused by concrete cracks, with construction joint leakage accounting for about 20%, and groundwater pressure and soil permeability accounting for about 10%. Therefore, setting the crack resistance risk weight to 0.5, the weak waterproofing parameter to 0.3, and the joint proximity parameter to 0.2 aligns with actual engineering conditions. In this embodiment, based on the experimental data and crack resistance risk values ​​in Table 1... Calculate and obtain the risk value of waterproof failure See Table 2.

[0029] Traditional waterproofing designs typically treat crack resistance and waterproofing as two separate systems. Waterproofing measures are uniformly set according to the waterproofing grade, neglecting the decisive impact of concrete cracks on waterproofing performance. This leads to the common problem of good waterproofing but leaks after cracking. This approach, for the first time, incorporates crack resistance risk as a core influencing factor of waterproofing failure into the evaluation system. It also combines weak point parameters and joint proximity parameters to achieve an integrated, coupled evaluation of crack resistance and waterproofing, addressing waterproofing failure caused by concrete cracks at its source. This overcomes the shortcomings of traditional waterproofing designs, enabling waterproofing measures to specifically cover high-risk areas most prone to leakage, thus improving the reliability and durability of the waterproofing system.

[0030] S4: Based on the crack resistance risk value and waterproofing failure risk value of each sub-region to be evaluated, determine the comprehensive protection requirement value of each sub-region to be evaluated; In this embodiment, the comprehensive protection requirement value of each sub-region to be evaluated is determined by: calculating and normalizing to the [0,1] interval using the Euclidean norm, and the calculation formula is as follows: in, Sub-region to be evaluated The comprehensive protection requirement value; crack resistance risk and waterproofing failure risk are two independent but closely related dimensions. Using the Euclidean norm (i.e., the distance from a point in two-dimensional space to the origin) can simultaneously consider the influence of both dimensions, reflecting the magnitude of the comprehensive risk better than a simple arithmetic average. For example, when =1.0、 When = 0, the arithmetic mean is 0.5, while the Euclidean norm is . This better reflects the reality that while the area has low waterproofing requirements, it has extremely high crack resistance requirements. Divided by This is to normalize the comprehensive protection requirement value to the [0,1] interval, maintaining consistency with the previous risk values ​​and facilitating subsequent classification and comparison of protection levels. The risk value for each sample was calculated strictly according to the formula in this technical solution, and the calculation results are shown in Table 2 below: Table 2: Risk Value Calculation Results Please see Figure 2 Based on unified preset parameters and engineering experience weighting coefficients, the crack resistance risk value, waterproofing failure risk value, and comprehensive protection requirement value of 10 samples were accurately calculated. The calculation results fully cover all four protection levels from Level IV to Level I, with the risk value increasing from a minimum of 0.0265 to a theoretical maximum of 1.0, showing a clear gradient distribution pattern. Among them, sample 10, as the theoretical highest risk point, showed calculation results that fully conformed to the formula boundary conditions, verifying the correctness of the calculation logic. This table directly provides a quantitative basis for the subsequent sub-regional protection classification and differentiated construction measures formulation.

[0031] Traditional protection schemes are typically formulated based on a single indicator such as crack resistance risk or waterproofing requirements, failing to simultaneously address the comprehensive requirements of both. This results in some areas meeting crack resistance requirements but lacking waterproofing, or vice versa. This step uses the Euclidean norm to calculate the comprehensive protection requirement value, which simultaneously reflects the crack resistance and waterproofing requirements of a sub-area. This avoids the one-sidedness of single-indicator assessments and makes the classification of protection levels more scientific and reasonable. It serves as a bridge connecting risk assessment and protection measures; the comprehensive protection requirement value directly determines the protection level of a sub-area, providing a clear basis for subsequent differentiated protection.

[0032] S5: Based on the comprehensive protection requirements of each sub-region to be evaluated, the sub-regions to be evaluated are classified, and the sub-regions to be evaluated that reach the preset level are identified as target sub-regions that need to be strengthened in terms of crack resistance and waterproof protection, while other sub-regions are classified as non-target sub-regions. In this embodiment, the sub-region to be evaluated is classified into four protection levels based on the comprehensive protection requirement value: Level I: Level II: Level III: Level IV: <0.3; The preset protection enhancement trigger level is Level II or above, which means all comprehensive protection requirements are set to... Sub-areas with a crack resistance of ≥0.6 were identified as target sub-areas requiring enhanced crack resistance and waterproofing. The protection enhancement trigger level was determined to be Level II or higher, meaning all areas meeting the requirements... The sub-area to be evaluated was identified as the target sub-area requiring enhanced crack resistance and waterproofing protection, while the remaining sub-areas were classified as non-target sub-areas. Different colors were used to mark the sub-areas of each protection level in the BIM model, generating a sidewall protection level distribution map to guide on-site construction. The grading standard design basis is based on statistical analysis of concrete cracking and leakage data from over 100 underground engineering projects in China. when At that time, the concrete cracking rate exceeded 80% and the leakage rate exceeded 60%, requiring the implementation of special-grade reinforced protective measures; when At that time, the incidence of concrete cracks was approximately 40%–80%, and the leakage rate was approximately 20%–60%, requiring enhanced protective measures. when At that time, the occurrence rate of concrete cracks was about 10% to 40%, and the leakage rate was about 5% to 20%. Conventional protective measures can meet the requirements. when When the concrete cracking rate is less than 10% and the leakage rate is less than 5%, basic protective measures are sufficient. The reason for choosing 0.6 as the protection enhancement trigger level is that when the comprehensive protection requirement value exceeds 0.6, the risk of cracks and leakage will increase significantly, and reinforcement measures must be taken to ensure the quality of the project; while when it is below 0.6, conventional measures can meet the requirements without additional costs; the protection levels of the 10 samples in this embodiment are shown in Table 2.

[0033] Traditional construction methods employ a uniform protection scheme, using the same concrete mix and waterproofing measures across all areas. This results in insufficient protection in high-risk areas and excessive protection in low-risk areas, increasing construction costs and compromising project quality. This new approach divides sub-areas into four protection levels based on comprehensive protection requirements, only strengthening protection for high-risk areas at level II and above. This achieves targeted protection and precise implementation, significantly reducing construction costs while ensuring project quality. It also achieves a match between risk and protection, allowing limited resources to be concentrated on the most critical high-risk areas, improving resource utilization efficiency, simplifying construction management, and facilitating quality control.

[0034] S6: Prepare hybrid fiber crack-resistant concrete, determine the composition of concrete raw materials and fiber mixing parameters, obtain the conventional concrete mix ratio required for non-target sub-regions and the optimal concrete mix ratio corresponding to the target sub-regions that need enhanced crack resistance and waterproof protection, determine the length of the side wall pouring segments, and pour each sub-region in layers.

[0035] In this embodiment, hybrid fiber-reinforced crack-resistant concrete is prepared. The conventional and optimal mix proportion concrete materials use the same baseline raw materials, with adjustments only made to the dosage of mineral admixtures, fibers, and additives, ensuring that the design strength of concrete with different mix proportions is C40. In this embodiment, differentiated concrete mix proportion schemes are formulated according to the protection level, with specific parameters shown in Table 3 below. Table 3: Differentiated Concrete Mix Design Table This embodiment employs a progressive fiber reinforcement system for different protection levels. Level IV and III non-target areas use a standard ratio of single polypropylene monofilament fibers; Level II target areas use a binary hybrid system of polypropylene and end-hooked steel fibers; and Level I special protection areas additionally incorporate basalt fibers to form a ternary hybrid system. Simultaneously, by increasing the fly ash content (from 20% to 25%) and the polycarboxylate superplasticizer content (from 1.0% to 1.2%), the heat of hydration and shrinkage strain of the concrete are further reduced, precisely matching the crack resistance and waterproofing requirements of different areas while ensuring strength.

[0036] Furthermore, determining the segment length of the sidewall pouring specifically involves: setting a lower threshold for the segment length of the sidewall pouring, and calculating the segment length of the sidewall pouring based on the maximum crack resistance risk value of all sub-regions within the segment. Binding, the calculation formula is: in, The length of the side wall pouring segment is specified. A minimum threshold for the pre-set sidewall pouring segment length is established; the ends of all pouring segments are set at... Within the IV-level sub-region with a value ≤0.3. In this embodiment... If the segments are too short, it will increase the number of construction joints, which will increase the risk of waterproofing problems; adjust the end position of the pouring segments to ensure that the ends of all pouring segments are set at the bottom. Within the Class IV sub-region with a crack strength ≤0.3, construction joints are strictly prohibited in high-risk areas. The longer the concrete pouring segment, the greater the accumulation of hydration heat, the higher the temperature stress and shrinkage stress, and the higher the risk of cracking. Therefore, the pouring length in the formula has a linear negative correlation with the maximum cracking risk value; the higher the risk, the shorter the segment. Coefficients 8 and 6 are determined based on extensive engineering practice: when... When there is no risk of cracking, the pouring length is 8m, which is the conventional pouring segment length for the sidewalls of underground engineering projects; That is, under the highest risk of cracking, the pouring length is 2m, which is the minimum acceptable segment length in engineering. (Introduction) Functions and lower thresholds This is to avoid excessive construction joints due to excessively short segments, which would increase the risk of waterproofing problems. When the length of the pouring segment increases from 0 to 1.0, it decreases linearly from 8m to 2m, indicating that the risk of cracking has a very significant impact on the length of the pouring segment.

[0037] The side walls are constructed using a layered continuous pouring method, with each layer not exceeding 500mm in thickness. The interval between two adjacent layers should not exceed the initial setting time of the concrete (≤2h). An immersion vibrator is used for compaction, with a vibrator movement distance not exceeding 300mm, inserting 50-100mm into the lower layer of concrete, ensuring quick insertion and slow withdrawal, and vibrating until the concrete surface shows a slurry layer and no air bubbles emerge. During the pouring of the target sub-area, the vibration frequency should be appropriately increased to ensure uniform fiber distribution and prevent fiber clumping. After the concrete is poured, it should be covered with geotextile for moisture retention within 12 hours, and the curing time should be no less than 14 days. For Level I protection areas, spray curing is used to ensure the concrete surface remains constantly moist.

[0038] In this embodiment, prestressing is applied to the Class I sharp curve segments and double-constrained areas corresponding to samples 8, 9, and 10: low-relaxation steel strands are used, with a tension control stress of 1116 MPa. Tensioning is carried out after the concrete strength reaches 75% of the design strength, and grouting and anchoring are performed promptly after tensioning. After adding prestressing, the maximum crack width, 28-day water seepage height, and Z-direction expansion deformation of the sidewall in the Class I area are all reduced. By combining prestressing technology with a risk classification system, prestressing tendons are precisely deployed only in the Class I high-risk areas. Compared with the scheme of applying prestressing to the entire section, more than 65% of the prestressing material cost can be saved. At the same time, it solves the industry pain point of insufficient crack resistance of single fibers in areas with large curvature and strong constraints, achieving the optimal balance between crack resistance and engineering cost.

[0039] Traditional construction methods employ uniform concrete mix proportions and fixed pouring segment lengths, which cannot adapt to the varying risks in different areas. High-risk areas are prone to cracking due to insufficient concrete crack resistance or excessively long pouring segments, while low-risk areas suffer from material waste. This step uses differentiated concrete mix proportions based on the protection level. While ensuring consistent strength, the crack resistance in high-risk areas is improved by adjusting the fiber and admixture dosages. Simultaneously, an adaptive pouring segment length is adopted, dynamically adjusting the segment length based on the maximum crack resistance risk value within each segment, effectively controlling temperature and shrinkage stresses. This is the final step in implementing the risk assessment results. The differentiated concrete mix proportions and adaptive pouring segment lengths directly determine the final crack resistance and waterproofing effect of the sidewall structure, and are key technical measures for achieving the objectives of this invention.

[0040] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0041] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0042] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0043] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange, characterized in that, The specific steps include: S1: Divide the main sidewall of the underground interchange into multiple sub-regions to be evaluated; for each sub-region to be evaluated, obtain the geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, load tensile stress parameters, joint proximity parameters, and waterproofing weakness parameters of that sub-region. S2: Based on geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature effect parameters, shrinkage strain values, and load tensile stress parameters, calculate the crack resistance risk value of each sub-region to be evaluated; S3: Calculate the waterproofing failure risk value of each sub-region to be evaluated based on the crack resistance risk value, waterproofing weakness parameter, and joint proximity parameter of each sub-region to be evaluated; S4: Based on the crack resistance risk value and waterproofing failure risk value of each sub-region to be evaluated, determine the comprehensive protection requirement value of each sub-region to be evaluated; S5: Based on the comprehensive protection requirements of each sub-region to be evaluated, the sub-regions to be evaluated are classified, and the sub-regions to be evaluated that reach the preset level are identified as target sub-regions that need to be strengthened in terms of crack resistance and waterproof protection, while other sub-regions are classified as non-target sub-regions. S6: Prepare hybrid fiber crack-resistant concrete, determine the composition of concrete raw materials and fiber mixing parameters, obtain the conventional concrete mix ratio required for non-target sub-regions and the optimal concrete mix ratio corresponding to the target sub-regions that need enhanced crack resistance and waterproof protection, determine the length of the side wall pouring segments, and pour each sub-region in layers.

2. The method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 1, characterized in that: The process of dividing the main sidewall of the underground interchange into multiple sub-areas to be evaluated is as follows: the sub-areas to be evaluated are divided according to the rule of basic grid and sensitive area densification. The basic segmentation unit is 2m along the longitudinal direction of the underground interchange sidewall, and the basic layering unit is 1.5m along the vertical direction of the sidewall, forming a basic evaluation grid of 2m×1.5m. Each independent grid is one sub-area to be evaluated.

3. The method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 1, characterized in that: For each sub-region to be evaluated, geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, tensile stress parameters, and joint proximity parameters are obtained through BIM model construction, site surveys, and construction planning. Among these, the geometric curvature parameters are directly extracted from the sub-region from the BIM model. Average radius of curvature at the centerline Then the geometric curvature parameter For a straight line segment, Consider it as infinitely large. Pick Structural constraint parameters are calculated by measuring the average thickness d of the sub-region and its rate of change δ along the length direction. The cross-sectional variation parameter is defined as follows: If there is no change in cross-section, Set to 0; this parameter is dimensionless.

4. A method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 1 or 3, characterized in that: The geometric curvature parameters, structural constraint parameters, cross-sectional change parameters, temperature parameters, shrinkage strain values, load tensile stress parameters, and joint proximity parameters are subjected to extreme value normalization and converted into dimensionless indices positively correlated with crack resistance risk in the interval [0,1]. Then, the crack resistance risk value of each sub-region to be evaluated is calculated using a weighted coupling formula, with a value range of [0,1]. The weighted coupling formula is as follows: in, Sub-region to be evaluated The crack resistance risk value, The normalized sub-region to be evaluated The geometric curvature parameters, For the normalized sub-region to be evaluated Structural constraint parameters, These are the normalized cross-sectional variation parameters. Sub-region to be evaluated The maximum principal tensile stress under the load, The preset standard value for the axial tensile strength of concrete. Sub-region to be evaluated Maximum internal and external temperature difference For reference temperature difference, Sub-region to be evaluated Shrinkage strain value, The preset reference shrinkage strain, These are the weighting coefficients for each item in the calculation of crack resistance risk value, and they satisfy... ; This is the index of the sub-region to be evaluated.

5. The method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 4, characterized in that: In step S3, the waterproofing weakness parameter is first normalized to convert it into a dimensionless index positively correlated with the waterproofing failure risk in the interval [0,1]. The normalized joint proximity parameter reuses the calculation result from step S2. Then, the waterproofing failure risk value of each sub-region to be evaluated is calculated using a coupling formula, with a value range of [0,1]. The coupling formula is as follows: In the formula: Sub-region to be evaluated The risk value of waterproof failure, Sub-region to be evaluated The weakest parameter in waterproofing, Sub-region to be evaluated Normalized seam proximity parameters, The weighting coefficients for each item in the calculation of the waterproofing failure risk value, and satisfying the following conditions:

1.

6. The method for constructing crack-resistant and waterproof concrete for the main side wall structure of an underground interchange according to claim 5, characterized in that: Step S4 describes determining the comprehensive protection requirement value for each sub-region to be evaluated: This is calculated using the Euclidean norm and normalized to the [0,1] interval. The calculation formula is as follows: in, Sub-region to be evaluated The comprehensive protection requirements.

7. A method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 6, characterized in that: The sub-regions to be evaluated are classified into four protection levels based on comprehensive protection requirements: Level I: Level II: Level III: Level IV: <0.3; The preset protection enhancement trigger level is Level II or above, which means all comprehensive protection requirements are set to... The sub-areas to be evaluated with a value ≥0.6 are identified as target sub-areas requiring enhanced crack resistance and waterproofing protection.

8. The method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 1, characterized in that: Hybrid fiber-reinforced crack-resistant concrete was prepared. The conventional and optimal mix proportion concrete materials used the same standard raw materials, with only the dosage of mineral admixtures, fibers, and additives adjusted to ensure that the design strength of concrete with different mix proportions was C40.

9. A method for constructing crack-resistant and waterproof concrete for the main sidewall structure of an underground interchange according to claim 7, characterized in that: The determination of the sidewall pouring segment length specifically involves: setting a lower limit threshold for the sidewall pouring segment length; calculating the sidewall pouring segment length based on the maximum crack resistance risk value of all sub-regions within the segment. Binding, the calculation formula is: in, The length of the side wall pouring segment is specified. A minimum threshold for the pre-set sidewall pouring segment length is established; the ends of all pouring segments are set at... Within the IV-level sub-region with a value ≤0.3.

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