PCR (Polymerase Chain Reaction) technology calculation method for asphalt overlay composite pavement of airport

Abstract

The invention relates to an airport asphalt overlay composite pavement PCR technology calculation method. The method comprises the following steps: S1, obtaining pavement structure parameters and aircraft traffic volume parameters; s2, calculating the equivalent thickness of the single-layer rigid pavement; s3, calculating ACR, determining a model corresponding to the maximum ACR value and an operation state of the model, and recording the model as AM; s4, calculating accumulated action times and allowable action times; s5, calculating a pavement fatigue accumulated damage factor and determining a key model; s6, calculating ACRG of the maximum allowable mass of the key model, and recording the ACRG as PCRi; s7, judging whether the key model is the model corresponding to the maximum ACR value in S3, if so, executing S8, otherwise, deleting the key model from the model combination, and returning to S5; and S8, calculating the PCR value of the evaluation pavement based on the PCRi of the key model. Compared with the prior art, the method has the advantages that the PCR calculation accuracy of the asphalt overlay composite pavement of the airport is improved, and the like.

Description

Technical Field

[0001] The invention relates to the technical field of airport PCR calculation, and in particular to a PCR technical calculation method for an airport asphalt overlaid composite pavement. Background Art

[0002] The airport pavement is the most important structural facility in the flight area. Ensuring that it has sufficient load-bearing capacity is crucial to flight safety. As the airport pavement ages, the pavement performance decays faster and the pavement load-bearing capacity decreases. Therefore, it is necessary to regularly test and evaluate the airport pavement structure load-bearing capacity to ensure safe aircraft operation.

[0003] The currently used airport pavement strength evaluation method is the ACN-PCN evaluation method. However, as the airport pavement structure design method has undergone major changes, the ACN-PCN technical evaluation method based on the inverse process of the traditional structural design method can no longer fully meet the requirements of pavement structure bearing capacity evaluation.

[0004] In the existing technology, pavements are divided into rigid pavements and flexible pavements. However, there is currently no unified standard for calculating PCR for asphalt-overlaid composite pavement structures, whether to classify them as rigid pavements or flexible pavements. In addition, for airports in my country that have been under construction for a long time, there is a need to strengthen the airport pavement structure. How to calculate the PCR of asphalt-overlaid composite pavements after the asphalt overlay project is a technical problem faced by airport authorities in my country when announcing the pavement strength grade PCR.

[0005] In view of the problem that there is currently a lack of calculation methods for the PCR of asphalt-overlaid composite pavements, the present invention proposes to equate the asphalt-overlaid pavement to a rigid pavement based on the principle of bending stiffness equivalence, and realizes accurate and efficient calculation of the PCR of asphalt-overlaid composite pavements based on the inverse process of my country's airport pavement structure design. Summary of the invention

[0006] The purpose of the present invention is to provide a PCR technical calculation method for an airport asphalt overlay composite pavement in order to improve the accuracy of PCR calculation of the airport pavement.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A PCR technology calculation method for an airport asphalt overlay composite pavement, the method comprising the following steps:

[0009] S1. Obtaining pavement structure parameters and aircraft traffic volume parameters, and reducing the thickness of the asphalt overlay layer and the thickness of the old cement concrete pavement slab in the pavement structure parameters;

[0010] S2. According to the bending stiffness equivalent principle, the thickness of the reduced asphalt overlay layer is converted into the thickness of the rigid layer, and combined with the reduced old cement concrete pavement to form a single-layer rigid pavement, and the equivalent thickness of the single-layer rigid pavement is calculated;

[0011] S3, calculating the ACR of each aircraft type in the aircraft type combination in the aircraft traffic volume parameter and determining the aircraft type and its operating status corresponding to the maximum ACR value, and the aircraft type corresponding to the maximum value is recorded as AM;

[0012] S4. Calculate the cumulative number of actions N of each model in the model combination based on equivalent thickness ij and the permissible number of actions N ei ;

[0013] S5. Calculate the maximum cumulative fatigue damage CDF of the aircraft type combination in the aircraft combination traffic volume max , find the CDF of max The model with the greatest contribution is the key model and is recorded as AC i ;

[0014] S6. Adjust the CDF of key models to CDF max , then CDF max is the maximum fatigue cumulative damage factor generated by all aircraft types at the beginning, and the maximum cumulative number of actions of the key aircraft type is obtained according to the allowable number of actions of the key aircraft type. The maximum cumulative number of actions of the key aircraft type is kept unchanged, and the weight of the key aircraft type in the obtained combination is adjusted until the maximum fatigue cumulative damage factor generated by the key aircraft type on the pavement is 1. The maximum allowable mass of the key aircraft type at this time is obtained, and the ACR value ACR of the key aircraft type at the maximum allowable mass is calculated. G , recorded as PCR i ;

[0015] S7. Determine the key model AC i Is it the model AM corresponding to the maximum ACR value in S3? If so, execute S8. Otherwise, delete the key model from the model combination to form a new model combination, and return to S5.

[0016] S8, PCR based on key models i Calculate the PCR value of the evaluation pavement.

[0017] Furthermore, the equivalent thickness is:

[0018]

[0019] Among them, h c is the equivalent thickness, h c1 Expressed as the thickness of the added asphalt layer; h c2 Expressed as the thickness of the old cement concrete slab; E c1Expressed as the modulus of the overlaid asphalt layer; E c2 Expressed as the modulus of old cement concrete slab.

[0020] Furthermore, the cumulative number of actions N ij for:

[0021] N ij =N i ×P ij

[0022] Among them, P ij is the distribution probability of the lateral displacement of the main landing gear load of the specified aircraft type i on the pavement at strip j during the evaluation period, N i It indicates the number of times the aircraft type i operates on the rigid pavement of the airport to be evaluated.

[0023] Furthermore, the distribution probability of the lateral displacement of the main landing gear load of the specified aircraft type i on the pavement at strip j during the evaluation period is:

[0024]

[0025] in,

[0026] σ—standard deviation of the lateral offset distribution of the main landing gear wheel track of aircraft i;

[0027] D j —The distance between the center line of strip j and the road surface guide line;

[0028] —The distance between the centerline of the wheel k of the main landing gear of aircraft i and the centerline of the taxiing guide of the runway, k=1, 2, ..., K, where K is the number of parallel transverse wheels in the main landing gear configuration. The value of K is determined according to the number of parallel transverse wheels in the main landing gear configuration. The K value of a single-axle single-wheel is 1, and the K value of a single-axle double-wheel, double-axle double-wheel, and three-axle double-wheel is 2;

[0029] W—Main landing gear wheel footprint width.

[0030] Further,

[0031] CDF max =Max(CDF j )

[0032] Among them, CDF j It represents the fatigue cumulative damage factor of the main landing gear of each model under the load at strip j.

[0033] Furthermore, the fatigue cumulative damage factor is:

[0034]

[0035] Among them, CDFij is the fatigue cumulative damage factor of the pavement at strip j under the load of the main landing gear of the specified aircraft type i (i = 1, 2, ..., I) during the evaluation period; I is the number of aircraft types running on the pavement during the evaluation period; N ij N is the cumulative number of times the main landing gear load of the specified aircraft type i acts at strip j during the evaluation period; ei The permissible number of pavement actions under the main landing gear load of the specified aircraft type i during the evaluation period.

[0036] Furthermore, the aircraft traffic volume parameters include: evaluation period, aircraft type combination and the number of operations of each aircraft type; the pavement structure parameters include the damage SCI, flexural strength, bending and tensile elastic modulus, thickness and Poisson's ratio of the asphalt pavement and old cement concrete pavement slab in the evaluation area, the rebound modulus, thickness, rebound modulus and Poisson's ratio of the base layer and cushion layer, and the reaction modulus of the top surface of the roadbed.

[0037] Furthermore, the specific steps of calculating the ACR of each aircraft type in the aircraft type combination in the aircraft traffic volume parameter are:

[0038] The ACR values ​​of various aircraft models at maximum and minimum weights are linearly interpolated to determine the ACR of each model, and the various models are sorted according to the size of the ACR values.

[0039] Furthermore, the PCR value of the evaluation pavement is the ACR of the key aircraft model at the maximum allowable quality. G .

[0040] Furthermore, the PCR value is used to evaluate the airport pavement bearing capacity.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention proposes to treat asphalt overlaid pavement as rigid pavement based on the bending stiffness equivalence principle, and then calculate the PCR of asphalt overlaid composite pavement through airport pavement structure parameters and operating aircraft traffic volume parameters. The calculation process takes into account factors such as the mechanical response of the pavement structure, pavement damage, multi-wheel and multi-axis effects, and lateral deviation of the wheel track. The cumulative damage factor is used as the conceptual basis for determining and publishing the pavement PCR and pavement design, thereby improving the accuracy of the PCR calculation of airport asphalt overlaid composite pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of the present invention;

[0044] Figure 2 is the cumulative damage distribution curve of pavement fatigue of each aircraft type in the present invention, where Figure 2 (a) is the fatigue cumulative damage distribution curve of all aircraft models. Figure 2(b) Distribution curve of fatigue cumulative damage under the combined action of other aircraft models after excluding the A321 key aircraft model. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0046] Glossary: ​​PCR (Pavement Classification Level) and ACR (Aircraft Classification Level).

[0047] The present invention proposes a PCR technology calculation method for airport asphalt overlay composite pavement, the flow chart of the method is as follows Figure 1 As shown, the method comprises the following steps:

[0048] S1. Obtaining pavement structure parameters and aircraft traffic volume parameters, and reducing the thickness of the asphalt overlay layer and the thickness of the old cement concrete pavement slab in the pavement structure parameters;

[0049] S2. According to the bending stiffness equivalent principle, the thickness of the asphalt overlay layer is converted into the thickness of the rigid layer, and combined with the old cement concrete pavement to form a single-layer rigid pavement, and the equivalent thickness of the single-layer rigid pavement is calculated;

[0050] S3, calculating the ACR of each aircraft type in the aircraft type combination in the aircraft traffic volume parameter and determining the aircraft type and its operating status corresponding to the maximum ACR value, and the aircraft type corresponding to the maximum value is recorded as AM;

[0051] S4. Calculate the cumulative number of actions N of each model in the model combination based on equivalent thickness ij and the permissible number of actions N ei ;

[0052] S5. Calculate the maximum cumulative fatigue damage CDF of the aircraft type combination in the aircraft combination traffic volume max , find the CDF of max The model with the greatest contribution is the key model and is recorded as AC i ;

[0053] S6. Adjust the CDF of key models to CDF max (At this time, CDF max is the maximum fatigue cumulative damage factor generated by all aircraft types at the beginning) and the maximum cumulative number of actions of the key aircraft type is obtained according to the allowable number of actions of the key aircraft type. The maximum cumulative number of actions of the key aircraft type is kept unchanged, and the weight of the key aircraft type in the obtained combination is adjusted until the maximum fatigue cumulative damage factor generated by the key aircraft type on the pavement is 1. The maximum allowable mass of the key aircraft type at this time is obtained, and the ACR of the key aircraft type at the maximum allowable mass is calculated.G , recorded as PCR i ;

[0054] S7, determine the key model (AC i ) is the model (AM) corresponding to the maximum ACR value in S3, if so, execute S8, otherwise delete the key model from the model combination, form a new model combination, and return to S5;

[0055] S8, PCR based on key models i Calculate the PCR value of the evaluation pavement.

[0056] S1: Determine the pavement structure parameters and aircraft traffic parameters. For existing asphalt overlaid composite pavements, the pavement structure parameters and aircraft traffic parameters are determined through testing or investigation; for asphalt overlaid composite pavements in the design stage, the pavement structure parameters and aircraft traffic parameters are taken according to the pavement design plan. Among them, the aircraft traffic parameters include: evaluation period, aircraft type combination and the number of operations of each aircraft type; the pavement structure parameters include the damage SCI, flexural strength, flexural elastic modulus, thickness and Poisson's ratio of the overlaid asphalt pavement and old cement concrete pavement slabs in the evaluation area, the rebound modulus, thickness, rebound modulus and Poisson's ratio of the base layer and cushion layer, and the reaction modulus of the top surface of the roadbed;

[0057] The method for collecting the flexural strength data of the asphalt pavement and cement concrete lower slab is as follows:

[0058] When there are airport pavement design documents, the flexural strength of the additional asphalt pavement and old cement concrete slabs shall be the design flexural strength of the evaluated area; when the design documents are missing, the flexural strength of the additional asphalt pavement and old cement concrete slabs shall be determined based on on-site core sample tests.

[0059] The method for determining the reduction in thickness of the asphalt overlay layer and the old cement concrete road slab is as follows:

[0060] The thickness of the asphalt overlay layer does not need to be reduced. The reduction coefficient of the old cement concrete pavement is shown in Table 1. For different ranges of SCI (such as 75≤SCI<85), the C value is determined by linear interpolation method:

[0061] Table 1 Reduction coefficient table

[0062]

[0063] The method for determining the value of the road condition index SCI is as follows:

[0064] The SCI value of the old cement concrete road slab is obtained through on-site testing.

[0065] The method for determining the thickness of the additional asphalt layer and the thickness of the old cement concrete slab is as follows:

[0066] The thickness of the added asphalt layer and the thickness of the old cement concrete road slab can be determined based on the analysis of the project completion data and then multiplied by the corresponding reduction factor; for airports where the completion data is lost or missing, data should be collected by on-site coring or ground penetrating radar and then multiplied by the corresponding reduction factor.

[0067] The data collection method of the additional asphalt layer, the bending and tension elastic modulus of the old cement concrete road slab, the rebound modulus of the base layer and the cushion layer, and the Poisson's ratio is as follows:

[0068] When there are airport pavement design documents, the flexural elastic modulus of the added asphalt layer, the old cement concrete pavement slab, and the rebound modulus of the base layer and the cushion layer are the design values ​​of the evaluation area; when the design documents are missing, they can be determined by referring to the "Technical Specifications for Evaluation and Management of Civil Airport Pavement" (MH / T 5024) based on the modulus inversion method of deflection detection.

[0069] The method for collecting Poisson's ratio data of each structural layer of the asphalt overlaid composite pavement is as follows:

[0070] The Poisson's ratio of each structural layer is determined by the value specified in the "Civil Airport Cement Concrete Pavement Design Code" (MH / T 5004).

[0071] The method for collecting the reaction modulus data of the roadbed top surface is as follows:

[0072] When there are airport pavement design documents, the top surface reaction modulus of the roadbed is the design value of the evaluated area; when the design documents are missing, it can be determined by referring to the "Technical Specifications for Evaluation and Management of Civil Airport Pavement" (MH / T 5024) based on the modulus inversion method of deflection detection.

[0073] The data collection method for the evaluation period is as follows:

[0074] For newly built airports, it should be consistent with the design reference period; for pavements that are already in operation, the evaluation period should be determined by the airport management agency, based on the expected usage time of the pavement in the area, and the evaluation period should not be less than 5 years.

[0075] The method for collecting the running data of the combination of the above-mentioned models and each model is as follows:

[0076] The combination of aircraft types and the number of operations of each type should be determined by estimation based on historical operation data. For historical operation data, the airport management agency should collect as long as possible historical data on flight takeoffs and landings. For airports with an operation time of more than 10 years, flight information should be collected for at least the past ten years.

[0077] The following method can be used to estimate the number of operations of each model during the evaluation period:

[0078] In the near future: Select no less than two of the trend extrapolation method, exponential smoothing method, market share method, regression analysis method, and BP neural network method for comprehensive forecasting and mutual calibration.

[0079] Long term: analogy analysis, Delphi method, comprehensive judgment method, etc.

[0080] New airports: road or rail transport diversion method, tourism-related analysis method, analogy analysis method, etc.

[0081] S2: According to the bending stiffness equivalent principle, the thickness of the added asphalt layer is converted into the thickness of the rigid layer, and combined with the old cement concrete pavement to form a single-layer rigid pavement. The equivalent thickness calculation method is as follows:

[0082]

[0083] Where E c , D g The calculation method is as follows:

[0084]

[0085]

[0086] Where h c1 Expressed as the thickness of the additional asphalt layer, cm; h c2 Expressed as the thickness of the old cement concrete slab, cm; E c1 Expressed as the modulus of the overlaid asphalt layer, MPa; E c2 Expressed as the modulus of old cement concrete slab, MPa.

[0087] S3: The ACR of each aircraft type in the computer model combination is determined by linear interpolation based on the ACR values ​​of the maximum and minimum weights of each type of aircraft provided in the "Technical Standards for Civil Airport Airfields" (MH 5001). The aircraft types are sorted according to the size of the ACR values, and the aircraft type and its operating status corresponding to the maximum ACR value are identified. The aircraft type corresponding to the maximum value is recorded as AM.

[0088] S4: The cumulative number of actions of each model in the computer type combination N ij and the permissible number of actions N ei .

[0089] The cumulative number of times N that the main landing gear load of the specified aircraft type i acts on the pavement at strip j is ij The calculation method is as follows:

[0090] Strip division: The pavement within 10m on both sides of the taxiing or running centerline is divided into strips horizontally, and the strip width is 0.25m.

[0091] Cumulative number of actions during the evaluation period Nij Calculate according to the following formula:

[0092] N ij =N i ×P ij

[0093] Among them, P ij is the distribution probability of the lateral displacement of the main landing gear load of the specified aircraft type i on the pavement at strip j during the evaluation period, calculated according to the following formula:

[0094]

[0095] Where:

[0096] σ—standard deviation of the lateral offset distribution of the main landing gear wheel track of aircraft i, m;

[0097] D j —The distance between the center line of strip j and the road surface guide line, m;

[0098] —The distance (m) between the centerline of the main landing gear wheel k (k=1, 2, ..., K) of aircraft i and the centerline of the taxiing guide on the runway, where K is the number of parallel transverse wheels in the main landing gear configuration. The value of K is determined according to the number of parallel transverse wheels in the main landing gear configuration. The K value of a single-axle single-wheel is 1, and the K value of a single-axle double-wheel, double-axle double-wheel, or three-axle double-wheel is 2;

[0099] W—Main landing gear wheel footprint width, m.

[0100] The permissible number of actions N of the main landing gear load for the specified aircraft type i ei It is calculated using the fatigue equation specified in the Code for Design of Cement Concrete Pavement for Civil Airports (MH / T 5004).

[0101] The maximum principal stress of the bottom of the designated aircraft model i under the main landing gear load acting on the critical load position of the runway panel is calculated using the finite element method.

[0102] S5: Calculate CDF under combined aircraft traffic max , determine the key models.

[0103] The maximum cumulative fatigue damage of the airport pavement is calculated according to the following formula:

[0104] CDF max =Max(CDF j )

[0105]

[0106] In the superposition process, the CDF is calculated separately according to the takeoff and landing of each aircraft type, and the original CDF of each aircraft type is split into takeoff and landing, which can be regarded as two types of takeoff and landing. j represents the fatigue cumulative damage factor of each aircraft type under the main landing gear load at strip j; I is the number of aircraft types running on the pavement during the evaluation period. Among them, the fatigue cumulative damage factor of the pavement panel at strip j under the main landing gear load of the specified aircraft type i (i=1,2,……,I) is calculated according to the following formula:

[0107]

[0108] Among them, N ij N is the cumulative number of times the main landing gear load of the specified aircraft type i acts at strip j during the evaluation period; ei The permissible number of pavement actions under the main landing gear load of the specified aircraft type i during the evaluation period.

[0109] Find the CDF of max The model with the greatest contribution is the key model and is recorded as AC i .

[0110] S6: Calculate PCR based on the determined key aircraft type and aircraft combination. Adjust the CDF generated by the key aircraft type to CDF max (At this time, CDF max is the maximum fatigue cumulative damage factor generated by all aircraft types at the beginning), and the maximum cumulative number of actions of the key aircraft type is calculated based on the allowable number of actions of the key aircraft type. Keep the calculated maximum cumulative number of actions of the key aircraft type unchanged, adjust the weight of the key aircraft type until the CDF value generated by the key aircraft type acting on the pavement is 1, record this weight, and interpolate the ACR of the key aircraft type at this weight according to the "Technical Standards for Civil Airport Airfields" (MH 5001), recorded as PCR i .

[0111] S7: If the key model (AC i ) is the model (AM) with the largest ACR value in the aircraft combination list, and jump to S8. If the key model is not the model with the largest ACR value in the aircraft combination list, then the key model is removed to form a new aircraft combination list, and S5-S6 are repeated until the key model is the model corresponding to the largest ACR value in the aircraft list;

[0112] S8: Calculate the PCR value of the evaluation surface, PCR = max PCR i , the final result needs to be rounded.

[0113] The final PCR is the pavement classification level, which is used to evaluate the airport pavement bearing capacity:

[0114] When the aircraft ACR does not exceed PCR, the aircraft can operate on the runway without restrictions;

[0115] When the aircraft ACR exceeds the PCR but does not exceed 1.10 times the PCR, the aircraft may operate with restrictions, provided that the number of overload operations per year does not exceed 5% of the total number of operations per year;

[0116] When the aircraft ACR exceeds 1.10 times the PCR, a special overload operation evaluation of the runway is required.

[0117] The present invention unifies the pavement structure design and pavement evaluation system. The present invention proposes a PCR technical calculation method for asphalt overlaid composite pavement based on the bending stiffness equivalence principle and the inverse process of my country's pavement structure design for asphalt overlaid composite pavement. The calculation process takes into account factors such as the pavement structure mechanical response, pavement damage, multi-wheel and multi-axis influence, and lateral deviation of the wheel track. The cumulative damage factor is used as the conceptual basis for determining and publishing PCR and pavement design, which solves the shortcomings of the previous ACN-PCN evaluation method and the current lack of PCR calculation methods for asphalt overlaid composite pavements. The evaluation results can truly reflect the actual bearing capacity of my country's airport pavements.

[0118] During the actual experiment, the present invention performs the following steps:

[0119] S1: Obtain pavement structure parameters and aircraft traffic volume parameters. In this embodiment, the pavement to be evaluated is an existing asphalt overlay composite pavement. The pavement structure includes four layers: asphalt surface layer, cement concrete lower layer, upper base layer, and lower base layer. The pavement structure parameters are determined through field tests: the flexural tensile strength of the asphalt surface layer and the cement concrete lower layer, and the thickness of each structural layer are determined through field core sample tests; the modulus of each structural layer of the pavement and the roadbed reaction modulus are obtained by inverting the test data of the bending and settlement test, wherein the modulus of the surface layer is calculated according to the formula; the Poisson's ratio data of each structural layer is determined by the values ​​specified in the "Civil Airport Cement Concrete Pavement Design Code" (MH / T 5004).

[0120] Evaluation period for testing airports p , evaluate the aircraft type and test the annual operation times N of each aircraft type at the airport i According to Articles 1 and 2 of D.0.6 of the Technical Specifications for Civil Airport Pavement Evaluation Management (MH / T 5024), it is determined as follows:

[0121] A1) The airport management agency or technical personnel determine the evaluation period according to the airport's use requirements. In this embodiment, the evaluation period is the service life of the pavement that can meet the airworthiness requirements since its construction.

[0122] A2) Determine the aircraft mix and annual flight times of the airport in the following way:

[0123] A21) Determine the aircraft type combination based on the actual operation of the airport, determine the annual average number of flights based on the airport's air traffic statistics for the past five years, and determine the annual number of flights of different aircraft types based on the annual average number of flights and the aircraft type combination.

[0124] A22) Determine the airport's aircraft mix and the annual operating numbers of different aircraft types based on the airport master plan document.

[0125] The parameters of each operating aircraft model at the inspection airport are obtained based on the "Civil Airport Cement Concrete Pavement Design Specifications" (MH / T5004).

[0126] S2: According to the bending stiffness equivalence principle, the thickness of the asphalt overlay layer is converted into the thickness of the rigid layer, and combined with the old cement concrete pavement to form a single-layer rigid pavement, and the equivalent thickness of the single-layer rigid pavement is calculated.

[0127] S3: Based on the aircraft type combination determined in S1, according to the ACR values ​​of the maximum and minimum weights of various aircraft types provided in the "Technical Standards for Civil Airport Airfields" (MH 5001), linear interpolation is used to determine the ACR of each aircraft type, and the aircraft types are sorted according to the size of the ACR values. The aircraft type corresponding to the maximum ACR value and its take-off and landing operating status are clarified, and the aircraft type corresponding to the maximum value is recorded as AM.

[0128] S4: The allowable number of actions N for each machine type in the computer type combination ei The cumulative number of actions on each strip of the runway N ij .

[0129] S5: The permissible number of actions N calculated based on S4 ei And the cumulative number of actions N ij , calculate the maximum cumulative fatigue damage CDF of the pavement under the combined aircraft traffic volume max , and determine the key models.

[0130] S6: Calculate PCR based on the determined key aircraft type and aircraft combination. Adjust the CDF generated by the key aircraft type to CDF max (At this time, CDF max is the maximum fatigue cumulative damage factor generated by all aircraft types at the beginning), and the maximum cumulative number of actions of the key aircraft type is calculated based on the allowable number of actions of the key aircraft type. Keep the calculated maximum cumulative number of actions of the key aircraft type unchanged, adjust the weight of the key aircraft type until the CDF value generated by the key aircraft type acting on the pavement is 1, record this weight, and interpolate the ACR of the key aircraft type at this weight according to the "Technical Standards for Civil Airport Airfields" (MH 5001), recorded as PCR i .

[0131] S7: If the ACR of the key aircraft type is the aircraft type (AM) with the largest ACR value in the aircraft combination list, stop the calculation and proceed to S7. If the ACR of the key aircraft type is not the aircraft type with the largest ACR value in the aircraft combination list, remove the key aircraft type to form a new aircraft combination list, and repeat S5-S6 until the key aircraft type (AC) is reached. i ) is the aircraft model (AM) corresponding to the maximum ACR value in the aircraft list, the calculation is stopped and S7 is performed.

[0132] S8: Calculate the PCR value of the evaluation surface, PCR = max PCR i .

[0133] Specifically, the embodiment selects a runway equipped with parallel taxiways at a 4F type airport in my country.

[0134] Through field test determination and design specification requirements, in this embodiment, the evaluation period is 20 years, the pavement panel bending tensile strength is 5.0MPa, and the pavement structure parameters and aircraft traffic volume parameters are shown in Table 2 and Table 3 respectively.

[0135] Table 2 Pavement structure parameters

[0136]

[0137] Table 3 Aircraft traffic parameters

[0138] Model Name Maximum take-off mass (kg) Main landing gear load distribution factor Annual aircraft takeoffs A319 71428 0.926 5616 A320 77960 0.929 37258 A321 84694 0.956 12501 A330-200 237755 0.95 1359 B737-800 80616 0.95 34628 B747-400 404993 0.952 179 B757-200 118010 0.95 1975 B777-300-ER 347133 0.936 211 B787-8 232582 0.913 405

[0139] According to the Technical Standards for Civil Airport Airfields (MH 5001), the ACR values ​​of the three aircraft types are interpolated. In this embodiment, the take-off ratio is 100%, and the average growth rate of the number of flights during the evaluation reference period is 5%. Therefore, only the ACR values ​​of the take-off status of the nine aircraft types are considered, and they are sorted by size, as shown in Table 3.

[0140] Table 3 ACR values ​​of various models

[0141] Model Name B777-300-ER B787-8 A330-200 B747-400 A321 Corresponding ACR 787 674 630 582 580 Model Name B737-800 A320 A319 B757-200 — Corresponding ACR 501 480 450 314 —

[0142] Based on the runway pavement structure and aircraft parameters, the allowable number of actions for nine aircraft types is calculated according to the fatigue equation in the Civil Airport Cement Concrete Pavement Design Specification (MH / T5004). The calculation results are shown in Table 4:

[0143] Table 4 Allowable number of actions for each model

[0144] Model Name B777-300-ER B787-8 A330-200 Critical stress (MPa) 2.621 2.530 2.414 Allowable number of actions 88532 238404 935091 Model Name B747-400 A321 B737-800 Critical stress (MPa) 2.418 2.405 2.239 Allowable number of actions 890101 1047613 9608569 Model Name A320 A319 B757-200 Critical stress (MPa) 2.129 1.902 1.805 Allowable number of actions 50557745 2855016396 21804914625

[0145] The cumulative damage distribution curves of pavement fatigue under the action of nine aircraft types were calculated and obtained. The results are shown in the attached figure. Figure 2As shown in (a), the key aircraft type in the current aircraft combination is A321, which is not the aircraft type corresponding to the maximum value in the ACR list. Therefore, A321 is eliminated. The cumulative damage distribution curves of pavement fatigue under the action of eight aircraft types, namely B777-300-ER, B787-8, A330-200, B747-400, B737-800, A320, A319 and B757-200, are calculated and obtained. The results are shown in the attached figure. Figure 2 As shown in (b), the key model is B777-300-ER, which is the model corresponding to the maximum value in the ACR list, and the calculation is ended.

[0146] By the attached Figure 2 (a) Obtain CDF max = 0.1450, according to the fatigue equation in the "Civil Airport Cement Concrete Pavement Design Specification" (MH / T5004) and the interpolation in the "Civil Airport Flight Area Technical Standard" (MH 5001), the maximum cumulative number of actions, maximum allowable mass, PCR of each aircraft type are calculated. i The calculation results are shown in Table 5.

[0147] Table 5 Calculation results list

[0148]

[0149]

[0150] PCR=max(PCR1,PCR2,PCR3,PCR4,PCR5,PCR6,PCR7,PCR8,PCR9)=956.23,

[0151] Rounded to 960, the PCR value of this runway is 960. The ACR values ​​of the above nine aircraft types are all less than PCR, indicating that these three aircraft are not subject to weight restrictions when operating on this runway.

[0152] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A PCR technology calculation method for airport asphalt overlay composite pavement, characterized in that: The method comprises the following steps: S1. Obtaining pavement structure parameters and aircraft traffic volume parameters, and reducing the thickness of the asphalt overlay layer and the thickness of the old cement concrete pavement slab in the pavement structure parameters; S2. According to the bending stiffness equivalent principle, the thickness of the reduced asphalt overlay layer is converted into the thickness of the rigid layer, and combined with the reduced old cement concrete pavement to form a single-layer rigid pavement, and the equivalent thickness of the single-layer rigid pavement is calculated; S3, calculating the ACR of each aircraft type in the aircraft type combination in the aircraft traffic volume parameter and determining the aircraft type and its operating status corresponding to the maximum ACR value, and the aircraft type corresponding to the maximum value is recorded as AM; S4. Calculate the cumulative number of actions N of each model in the model combination based on equivalent thickness ij and the permissible number of actions N ei ; S5. Calculate the maximum cumulative fatigue damage CDF of the aircraft type combination in the aircraft combination traffic volume max , find the CDF of max The model with the greatest contribution is the key model and is recorded as AC i ; S6. Adjust the CDF of key models to CDF max , then CDF max is the maximum fatigue cumulative damage factor generated by all aircraft types at the beginning, and the maximum cumulative number of actions of the key aircraft type is obtained according to the allowable number of actions of the key aircraft type. The maximum cumulative number of actions of the key aircraft type is kept unchanged, and the weight of the key aircraft type in the obtained combination is adjusted until the maximum fatigue cumulative damage factor generated by the key aircraft type on the pavement is 1. The maximum allowable mass of the key aircraft type at this time is obtained, and the ACR value ACR of the key aircraft type at the maximum allowable mass is calculated. G , recorded as PCR i ; S7. Determine the key model AC i Is it the model AM corresponding to the maximum ACR value in S3? If so, execute S8. Otherwise, delete the key model from the model combination to form a new model combination, and return to S5. S8, PCR based on key models i Calculate the PCR value of the evaluation pavement.

2. According to claim 1, a method for high-precision ship identification based on target detection and text recognition is characterized in that: The equivalent thickness is: Among them, h c is the equivalent thickness, h c1 Expressed as the thickness of the added asphalt layer; h c2 Expressed as the thickness of the old cement concrete slab; E c1 Expressed as the modulus of the overlaid asphalt layer; E c2 Expressed as the modulus of old cement concrete slab.

3. According to claim 1, a method for high-precision ship identification based on target detection and text recognition is characterized in that: Cumulative number of actions N ij for: N ij =N i ×P ij Among them, P ij is the distribution probability of the lateral displacement of the main landing gear load of the specified aircraft type i on the pavement at strip j during the evaluation period, N i It indicates the number of times the aircraft type i operates on the rigid pavement of the airport to be evaluated.

4. A high-precision ship identification method based on target detection and text recognition according to claim 3, characterized in that: The distribution probability of the lateral displacement of the main landing gear load of a specified aircraft type i on the pavement at strip j during the evaluation period is: in, σ—standard deviation of the lateral offset distribution of the main landing gear wheel track of aircraft i; D j —The distance between the center line of strip j and the road surface guide line; —The distance between the centerline of the wheel k of the main landing gear of aircraft i and the centerline of the taxiing guide of the runway, k=1, 2, ..., K, where K is the number of parallel transverse wheels in the main landing gear configuration. The value of K is determined according to the number of parallel transverse wheels in the main landing gear configuration. The K value of a single-axle single-wheel is 1, and the K value of a single-axle double-wheel, double-axle double-wheel, and three-axle double-wheel is 2; W—Main landing gear wheel footprint width.

5. According to claim 1, a method for high-precision ship identification based on target detection and text recognition is characterized in that: Maximum cumulative fatigue damage CDF max for: CDF max =Max(CDF j ) Among them, CDF j It represents the fatigue cumulative damage factor of the main landing gear of each model under the load at strip j.

6. A method for high-precision ship identification based on target detection and text recognition according to claim 5, characterized in that: The fatigue cumulative damage factor is: Among them, CDF ij is the fatigue cumulative damage factor of the pavement at strip j under the load of the main landing gear of the specified aircraft type i (i = 1, 2, ..., I) during the evaluation period; I is the number of aircraft types running on the pavement during the evaluation period; N ij N is the cumulative number of times the main landing gear load of the specified aircraft type i acts at strip j during the evaluation period; ei The permissible number of pavement actions under the main landing gear load of the specified aircraft type i during the evaluation period.

7. The method for high-precision ship identification based on target detection and text recognition according to claim 1 is characterized in that: The aircraft traffic volume parameters include: evaluation period, aircraft type combination and the number of operations of each aircraft type; the pavement structure parameters include the damage SCI, flexural strength, bending and tensile elastic modulus, thickness and Poisson's ratio of the asphalt pavement and old cement concrete pavement slab in the evaluation area, the rebound modulus, thickness, rebound modulus and Poisson's ratio of the base layer and cushion layer, and the reaction modulus of the top surface of the roadbed.

8. The method for high-precision ship identification based on target detection and text recognition according to claim 1 is characterized in that: The specific steps of calculating the ACR of each aircraft type in the aircraft type combination in the aircraft traffic volume parameter are: The ACR values ​​of various aircraft models at maximum and minimum weights are linearly interpolated to determine the ACR of each model, and the various models are sorted according to the size of the ACR values.

9. The method for high-precision ship identification based on target detection and text recognition according to claim 1, characterized in that: The PCR value of the evaluated pavement is the ACR of the key aircraft model at the maximum allowable mass. G .

10. The method for high-precision ship identification based on target detection and text recognition according to claim 1, characterized in that: The PCR value is used to evaluate the bearing capacity of airport pavement.

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