Design method for permeable pavement of road in booster station

Abstract

The invention belongs to the field of road engineering, discloses a method for designing a permeable pavement of a road in a booster station, solves the problem that a permeable pavement design scheme in the prior art is not accurate enough, and provides an accurate and scientific reference basis for the design of the road in the booster station. According to the method, corresponding test standard test pieces are formed by selecting different aggregate grading schemes and determining different cement dosages in the cement dosage percentage range, the water seepage performance and the structural strength performance of the test pieces are tested, and the correlation of performance indexes is obtained through correlation analysis; adjusting the mix proportion of the test pieces according to a correlation analysis result, screening out the test pieces with the water seepage performance and the structural strength performance meeting the requirements, and judging whether the whole pavement adopting the test pieces meets the water seepage requirement or not through seepage simulation of a finite element road model. The method is suitable for the design of the permeable pavement in the booster station.

Description

Technical Field

[0001] The invention belongs to the field of road engineering, and in particular relates to a method for designing a permeable pavement of a road in a booster station. Background Art

[0002] Traditionally, the roads inside booster stations are made of hardened impermeable pavement. The use of a large amount of impermeable pavement inside the station means that rainwater often cannot be drained away in time during rainy seasons. Rainwater accumulates quickly on the road surface and cannot seep in quickly. It can only be drained naturally through the cross slope of the road, causing waterlogging on the road.

[0003] Permeable pavement has a large porosity and water permeability coefficient, so that rainwater can infiltrate from the inside of the pavement through the large-void permeable pavement, and will not gather on the road surface to form runoff. The reduction of runoff can alleviate flooding in the booster station and increase the safety of booster station operation and maintenance. Generally speaking, the larger the porosity of the permeable pavement structure, the better the drainage performance, but the larger the porosity, the lower its structural strength. In addition, the cement dosage of the permeable base will also affect the porosity of the cement-stabilized gravel base. Too much cement dosage will block the voids in the formed skeleton void structure, but too little cement dosage will not meet the requirements of structural strength. It should have the largest possible permeability coefficient while meeting the minimum structural strength requirements.

[0004] In the prior art, when designing permeable concrete pavement, the void ratio and mix ratio of concrete are designed according to the drainage requirements that the pavement needs to achieve, but the relationship between the void ratio and the water permeability coefficient of different mix ratios of the mixture is not considered to change, and the actual water permeability efficiency is not considered through simulation. It is ignored that the actual road has a certain road width, and the water storage and drainage capacity of the road as a whole in the rainy season is not studied. Therefore, the permeable pavement design scheme in the prior art is not accurate enough, and the designed permeable pavement may have certain defects in actual application. Summary of the invention

[0005] The technical problem to be solved by the present invention is to propose a method for designing permeable pavement of roads in booster stations, solve the problem that the permeable pavement design scheme in the prior art is not accurate enough, and provide an accurate and scientific reference basis for the design of roads in booster stations.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for designing a permeable pavement of a road in a booster station comprises the following steps:

[0008] S1. Select different crushed stone aggregate grading schemes according to design specifications;

[0009] S2. Determine the percentage range of cement dosage;

[0010] S3. According to different aggregate grading schemes and different cement dosages within the determined cement dosage percentage range, corresponding test standard specimens are formed;

[0011] S4. Measure the void ratio, water permeability, compressive strength and compressive resilience modulus parameters of each test standard specimen;

[0012] S5. According to the test data of step S4, a correlation fitting analysis is performed on the parameters of porosity, water permeability, compressive strength, and compressive rebound modulus;

[0013] S6. Adjust the material ratio in the test piece according to the correlation fitting analysis results, and reshape the corresponding test standard test piece until the test standard test piece whose water permeability, compressive strength and compressive rebound modulus meet the design requirements is selected;

[0014] S7. Using finite element analysis software to establish a pavement seepage finite element model of the target road, and importing the void ratio of the test standard specimen that meets the design requirements and the pre-acquired rainfall intensity conditions of the target road area, to simulate the pavement seepage of the target road designed with the test standard specimen under rainfall intensity conditions;

[0015] S8. Based on the simulation results of the pavement seepage finite element model of the target road, determine whether the overall pavement using the test standard specimen meets the water seepage requirements. If so, obtain a crushed stone aggregate mix ratio that meets the requirements; otherwise, return to step S6.

[0016] Furthermore, in step S1, when selecting different crushed stone aggregate grading schemes, the following conditions must be met:

[0017] The content of crushed stone aggregate with a particle size less than 4.75 mm is greater than 0 and less than or equal to 10%, of which the content of crushed stone aggregate with a particle size less than 0.075 mm is greater than 0 and less than or equal to 2%, and the maximum nominal particle size of all selected crushed stone aggregates does not exceed 26.5 mm.

[0018] Furthermore, in step S2, the determined cement dosage percentage range is 6% to 12%.

[0019] Furthermore, in step S3, a static pressing method is used to form a corresponding test standard specimen.

[0020] Furthermore, in step S7, the rainfall intensity condition of the target road area is obtained by collecting the rainfall recurrence period and rainfall time parameters of the area where the target road is located.

[0021] Furthermore, in step S8, the method for judging whether the overall pavement using the test standard specimen meets the water seepage requirement based on the simulation result of the pavement seepage finite element model of the target road includes:

[0022] Based on the simulation results of the pavement seepage finite element model of the target road, the location of the infiltration surface where the pore water pressure of the model is zero is determined within the pavement thickness range. If the infiltration surface rises to the surface, it means that the drainage is poor, and it is determined that the overall pavement using the test standard specimen does not meet the water seepage requirements.

[0023] The beneficial effects of the present invention are:

[0024] The present invention forms corresponding test standard specimens by selecting different aggregate grading schemes and determining different cement dosages within the cement dosage percentage range, and tests the water permeability and structural strength performance of the specimens, obtains the correlation of various performance indicators through correlation analysis, adjusts the mix ratio of the specimens according to the correlation analysis results, screens out specimens that meet the requirements for water permeability and structural strength performance, and then uses the seepage simulation of the finite element road model to determine whether the overall road surface using the specimen meets the water permeability requirements. In the simulation of the finite element model, the road width and the rainfall intensity conditions of the area where the road surface is located are taken into consideration, so that the road surface design scheme is more in line with the actual scene and more accurate.

[0025] The cement-stabilized crushed stone permeable base designed based on this scheme not only has a structure that meets the strength requirements, but also has a large porosity and water permeability coefficient, so that rainwater can infiltrate from the inside of the road surface through the large-void permeable pavement, and does not accumulate on the road surface to form runoff, thereby reducing flooding in the booster station and improving the safety of booster station operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flowchart of a method for designing a permeable pavement of a road in a booster station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention aims to provide a method for designing permeable pavement of roads in booster stations, solve the problem that the permeable pavement design scheme in the prior art is not accurate enough, and provide an accurate and scientific reference for the design of roads in booster stations. The core idea is: after selecting different crushed stone aggregate grading schemes and different cement dosages to combine, the mix ratio of the test pieces under different conditions is obtained, and then the test pieces are formed in the laboratory, and the parameters such as the void ratio, water permeability coefficient, compressive strength, and compressive rebound modulus of the test pieces are measured, and the correlation fitting analysis is performed according to the parameter data. According to the correlation analysis results, the mix ratio of the test pieces is adjusted, and the test pieces that meet the requirements of water permeability and structural strength performance are screened out, and then the finite element analysis software is used to establish the full width parameters of the road according to the data obtained from the test, and the seepage of rainfall on the actual road surface is fitted to determine whether the overall road surface using the test piece meets the water permeability requirements. This scheme can provide an accurate and scientific reference for the design of roads in booster stations.

[0028] In order to better understand the present invention, some terms involved in the present invention are explained below:

[0029] Void ratio: Void ratio refers to the percentage of voids in the binder to the total volume of the binder, and the voids in the binder refer to the remaining volume after deducting the volume occupied by the skeleton and cement. In the binder, voids generally exist in three forms: connected voids, closed voids, and semi-connected voids. Effective voids include connected voids and semi-connected voids that can discharge free water, and invalid voids are closed voids.

[0030] Water permeability coefficient: also known as hydraulic conductivity coefficient, it is defined as the unit flow rate under a unit hydraulic gradient, which represents the difficulty of the fluid passing through the gaps between the skeletons during the seepage process. The water permeability coefficient is closely related to the water permeability of the pavement. This indicator directly represents the drainage capacity of the pavement. The larger the water permeability coefficient, the less likely the pavement is to accumulate water and the better the water permeability.

[0031] Wetting surface: The point where the pore water pressure of the finite element model is zero is the wetting surface. The pavement material above the wetting surface is unsaturated, and the pavement material below the wetting surface is saturated. If the wetting surface is on the surface of the model, it means that the drainage is poor.

[0032] The scheme of the present invention is specifically described below in conjunction with the accompanying drawings and embodiments.

[0033] Example

[0034] See also Figure 1 The permeable pavement design method for the road in the booster station proposed in this embodiment includes the following implementation steps:

[0035] S1. Select different crushed stone aggregate grading schemes according to design specifications;

[0036] In this step, the crushed stone aggregate gradation scheme is a distribution scheme of crushed stone aggregates of different particle sizes. In an exemplary embodiment, when selecting different crushed stone aggregate gradation schemes, it is necessary to meet the following requirements: the content of crushed stone aggregates with a particle size less than 4.75 mm is greater than 0 and less than or equal to 10%, wherein the content of crushed stone aggregates with a particle size less than 0.075 mm is greater than 0 and less than or equal to 2%, and the maximum nominal particle size of all selected crushed stone aggregates does not exceed 26.5 mm.

[0037] Since the cement-stabilized crushed stone permeable base is a skeleton pore structure, in its material composition, if there are too many fine aggregates, they will be filled into the skeleton gaps formed by the coarse aggregates interlocking with each other, resulting in blockage of the gaps in the skeleton, thereby affecting the drainage performance; and if there are too few fine aggregates, the cementing layer inside the structure will be very weak, the contact points between the fine aggregates wrapped by cement slurry and the coarse aggregates in the structure will be reduced, the bond strength of the structure formed will be low, and the overall strength and stability of the structure will be poor. In view of this, considering the water permeability and structural strength performance, this embodiment controls the content of crushed stone aggregates with a particle size of less than 4.75 mm to be greater than 0 and less than or equal to 10%. In addition, considering that the cement-stabilized crushed stone base should have good fatigue resistance, the crushed stone aggregate should also contain fine aggregates below 0.075 mm, and in order to ensure the water permeability as much as possible, the content of fine aggregates below 0.075 mm should be controlled to be no more than 2%. Finally, the maximum nominal particle size of aggregate is controlled not to exceed 26.5mm. This is because when the coarse aggregate is larger, the mixture is prone to segregation, which will affect the quality and uniformity of the road.

[0038] S2. Determine the percentage range of cement dosage;

[0039] In this step, since the bonding effect of cement between aggregates also provides a part of the strength, it also determines the mechanical properties of cement-stabilized crushed stone mixture to a certain extent. Too much cement will block the internal gaps of the aggregates and reduce the water permeability of the material. Too little cement will result in too low material strength. Therefore, after comprehensive consideration, in an exemplary embodiment, the cement dosage percentage ranges from 6% to 12%.

[0040] S3. According to different aggregate grading schemes and different cement dosages within the determined cement dosage percentage range, corresponding test standard specimens are formed;

[0041] In this step, the specimen material mix ratio under different conditions can be obtained according to different aggregate grading schemes and different cement dosage combinations within the determined cement dosage percentage range, and then the test standard specimens of the corresponding mix ratio can be formed in the laboratory by static pressing method for subsequent parameter measurement.

[0042] S4. Measure the void ratio, water permeability, compressive strength and compressive resilience modulus parameters of each test standard specimen;

[0043] In this step, the porosity and water permeability coefficient can reflect the drainage performance of the specimen, while the compressive strength and compressive rebound modulus can reflect the structural performance over time. The specific measurement methods of these parameters belong to the existing technology and will not be repeated here.

[0044] S5. According to the test data of step S4, a correlation fitting analysis is performed on the parameters of porosity, water permeability, compressive strength, and compressive rebound modulus;

[0045] In this step, by performing correlation fitting analysis on the void ratio, water permeability, compressive strength, and compressive rebound modulus parameters, the correlation coefficient between these parameters can be calculated to quantify the linear relationship between the parameters, so that in subsequent steps, the drainage performance and structural performance can be comprehensively considered according to the correlation analysis results between the parameters to adjust the mix ratio.

[0046] S6. Adjust the material ratio in the test piece according to the correlation fitting analysis results, and reshape the corresponding test standard test piece until the test standard test piece whose water permeability, compressive strength and compressive rebound modulus meet the design requirements is selected;

[0047] In this step, the correlation analysis results between various parameters are used as the basis for adjusting the material mix ratio of the specimen, which can accurately and quickly guide the adjustment of the mix ratio. By adjusting the mix ratio, the specimen is molded again, and the parameters such as porosity, water permeability coefficient, compressive strength, and compressive rebound modulus are measured. This process is repeated until the test standard specimens whose water permeability, compressive strength, and compressive rebound modulus meet the design requirements are screened out.

[0048] S7. Using finite element analysis software to establish a pavement seepage finite element model of the target road, and importing the void ratio of the test standard specimen that meets the design requirements and the pre-acquired rainfall intensity conditions of the target road area, to simulate the pavement seepage of the target road designed with the test standard specimen under rainfall intensity conditions;

[0049] In this step, the rainfall intensity condition of the target road area is obtained by collecting the rainfall recurrence period and rainfall time parameters of the target road area in advance. Then, the pavement seepage finite element model of the target road is established based on the test parameters of the specimen selected in step S6 using the finite element analysis software, and the pavement seepage condition of the target road designed with the test standard specimen under the rainfall intensity condition is simulated by inputting the void ratio of the specimen and the rainfall intensity condition of the target road area.

[0050] S8. Based on the simulation results of the pavement seepage finite element model of the target road, determine whether the overall pavement using the test standard specimen meets the water seepage requirements. If so, obtain a crushed stone aggregate mix ratio that meets the requirements; otherwise, return to step S6.

[0051] In this step, in the pavement seepage finite element model, the location of the infiltration surface is where the pore water pressure of the model is zero. During the simulation, if the infiltration surface rises to the surface, it means that the drainage is not smooth, and it is determined that the overall pavement using the test standard specimen does not meet the water seepage requirements. Then, according to the results of the correlation fitting analysis, the material mix ratio in the specimen is adjusted, the specimen is re-molded, the water seepage performance and strength performance of the specimen are judged again, and the finite element simulation is performed again until a specimen that meets the requirements is finally obtained.

[0052] Finally, it should be noted that the above embodiments are only preferred implementations and are not intended to limit the present invention. It should be pointed out that for those skilled in the art, several modifications, equivalent replacements, improvements, etc. can be made without departing from the scope of the present invention and the scope of protection of the claims, and all of these should be included in the protection scope of the present invention.

Claims

1. A method for designing a permeable pavement for a road in a booster station, characterized in that: The following steps are involved: S1. Select different crushed stone aggregate grading schemes according to design specifications; S2. Determine the percentage range of cement dosage; S3. According to different aggregate grading schemes and different cement dosages within the determined cement dosage percentage range, corresponding test standard specimens are formed; S4. Measure the void ratio, water permeability, compressive strength and compressive resilience modulus parameters of each test standard specimen; S5. According to the test data of step S4, a correlation fitting analysis is performed on the parameters of porosity, water permeability, compressive strength, and compressive rebound modulus; S6. Adjust the material ratio in the test piece according to the correlation fitting analysis results, and reshape the corresponding test standard test piece until the test standard test piece whose water permeability, compressive strength and compressive rebound modulus meet the design requirements is selected; S7. Using finite element analysis software to establish a pavement seepage finite element model of the target road, and importing the void ratio of the test standard specimen that meets the design requirements and the pre-acquired rainfall intensity conditions of the target road area, to simulate the pavement seepage of the target road designed with the test standard specimen under rainfall intensity conditions; S8. Based on the simulation results of the pavement seepage finite element model of the target road, determine whether the overall pavement using the test standard specimen meets the water seepage requirements. If so, obtain a crushed stone aggregate mix ratio that meets the requirements; otherwise, return to step S6.

2. A method for designing a permeable pavement in a booster station as claimed in claim 1, characterized in that: In step S1, when selecting different crushed stone aggregate grading schemes, the following conditions must be met: The content of crushed stone aggregate with a particle size less than 4.75 mm is greater than 0 and less than or equal to 10%, of which the content of crushed stone aggregate with a particle size less than 0.075 mm is greater than 0 and less than or equal to 2%, and the maximum nominal particle size of all selected crushed stone aggregates does not exceed 26.5 mm.

3. A method for designing a permeable pavement in a booster station as claimed in claim 1, characterized in that: In step S2, the determined cement dosage percentage range is 6% to 12%.

4. A method for designing a permeable pavement in a booster station as claimed in claim 1, characterized in that: In step S3, a static pressing method is used to form a corresponding test standard specimen.

5. A method for designing permeable pavement in a booster station as claimed in claim 1, characterized in that: In step S7, the rainfall intensity condition of the target road area is obtained by collecting the rainfall recurrence period and rainfall time parameters of the area where the target road is located.

6. A method for designing a permeable pavement in a booster station as claimed in any one of claims 1 to 5, characterized in that: In step S8, the method for judging whether the overall pavement using the test standard specimen meets the water seepage requirement based on the simulation result of the pavement seepage finite element model of the target road includes: Based on the simulation results of the pavement seepage finite element model of the target road, the location of the infiltration surface where the pore water pressure of the model is zero is determined within the pavement thickness range. If the infiltration surface rises to the surface, it means that the drainage is poor, and it is determined that the overall pavement using the test standard specimen does not meet the water seepage requirements.

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