One-way moisture guiding functional layer structure of railroad bed and design method of one-way moisture guiding functional layer structure

Abstract

The invention provides a one-way moisture guiding functional layer structure of a railroad bed and a design method of the one-way moisture guiding functional layer structure, and belongs to the technical field of railroad bed engineering, the one-way moisture guiding functional layer structure comprises a flow guiding layer, a hydrophilic layer and a hydrophobic layer which are tightly attached in sequence from top to bottom, and the flow guiding layer, the hydrophilic layer and the hydrophobic layer form a three-layer composite structure; the flow guide layer is used for guiding and draining rainwater to the outer side of the roadbed and forming a channel for volatilizing and draining water in the hydrophilic layer; the hydrophilic layer is used for diffusing moisture; the hydrophobic layer is used for unidirectionally guiding water to the hydrophilic layer; the drainage layer is arranged at the upper end of the roadbed structure top face, and the diversion layer is arranged at the lower end of the track bed bottom face. According to the one-way moisture guiding functional layer structure of the railway roadbed and the design method thereof, the technical effects that infiltration and infiltration of moisture to the top face of the roadbed structure can be blocked, the one-way moisture guiding performance is kept, and accumulated water in the roadbed is discharged outwards are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of railway subgrade engineering, and more particularly relates to a one-way moisture guiding function layer structure of a railway subgrade and a design method thereof. BACKGROUND

[0002] The subgrade is a main off-line foundation structure form of the railway and belongs to a soil work structure filled by granular rock-soil materials. The top surface and the two side slopes of the subgrade are subjected to the infiltration and erosion of atmospheric precipitation, resulting in water damage deformation such as deterioration, settlement, frost heaving and arching of the filler, and further causing geometric irregularities of the upper track structure, threatening the driving safety. The high-speed railway has large traffic volume, high passing efficiency and short window time, and after being put into operation, it is difficult and costly to maintain, so it is necessary to take reasonable and effective anti-seepage structures in the design and construction stages.

[0003] The commonly used anti-seepage materials of the subgrade include high-density polyethylene film, composite geomembrane and concrete sealing layer. The problems faced by the above-mentioned anti-seepage structures of the subgrade are that the anti-seepage materials on the top surface of the subgrade bear the upper driving load, and the anti-seepage materials on the two side slopes of the subgrade bear the natural environmental weathering, and both of them can appear local damage. When the atmospheric precipitation forms surface runoff, it will seep into the inside of the subgrade from the damaged part of the anti-seepage structure and diffuse to form a wetting circle. At the same time, when the underground water level is shallow or the surface water is accumulated on the two sides of the subgrade, the water will also migrate to the inside of the subgrade by capillary effect or transpiration. Since the top surface and the two sides of the subgrade are covered by the anti-seepage materials except for the small area of the damaged part, there is no evaporation, moisture removal and drying process in the sunny day. Therefore, the local wetting body of the subgrade exists for a long time, and gradually forms unevenly distributed potholes and water bags, resulting in the emptying of the upper track structure, and further causing sudden accidents such as severe shaking and derailment.

[0004] It can be seen that in the design and construction of the railway subgrade in rainy areas, the technical requirements for the anti-seepage materials include both preventing the inward infiltration of atmospheric precipitation outside the subgrade and allowing the outward evaporation of the internal accumulated water of the subgrade. Therefore, it is necessary to develop a structure with one-way moisture guiding function to realize the outward discharge of the internal accumulated water of the subgrade. SUMMARY

[0005] The present application aims to provide a one-way moisture guiding function layer structure of a railway subgrade, and aims to solve the technical problems in the prior art that the anti-seepage structure of the subgrade is bidirectionally closed and impermeable, and the subgrade cannot be dried after seepage.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is: a one-way moisture guiding function layer structure of a railway roadbed is provided, which comprises a flow guiding layer, a hydrophilic layer and a hydrophobic layer which are sequentially and closely arranged from top to bottom, and the flow guiding layer, the hydrophilic layer and the hydrophobic layer form a three-layer composite structure; the flow guiding layer is used for guiding and draining rainwater to the outside of the roadbed and forming a channel for the evaporation and discharge of moisture in the hydrophilic layer; the hydrophilic layer is used for diffusing moisture; and the hydrophobic layer is used for one-way guiding and conveying moisture to the hydrophilic layer; wherein the hydrophobic layer is arranged at the upper end of the top surface of the roadbed structure, and the flow guiding layer is arranged at the lower end of the bottom surface of the track bed.

[0007] In a possible implementation manner, the material of the flow guiding layer is water permeable concrete, and the aggregate particle size of the water permeable concrete is 25mm-35mm.

[0008] In a possible implementation manner, the open porosity of the water permeable concrete is 20%-30%.

[0009] In a possible implementation manner, the material of the hydrophilic layer is modified mortar, and the modified mortar is a mixed material composed of a hydrophilic finishing agent, water and machine-made sand.

[0010] In a possible implementation manner, the hydrophilic finishing agent is selected from a hydrophilic organic silicon, and the mixing mass ratio of the hydrophilic organic silicon is 0.4%-0.6%.

[0011] In a possible implementation manner, the material of the hydrophobic layer is modified asphalt concrete, and the modified asphalt concrete is a mixed material composed of a hydrophobic finishing agent, graded gravel and asphalt.

[0012] In a possible implementation manner, the mixing amount of the hydrophobic finishing agent gradually decreases from top to bottom along the thickness direction of the hydrophobic layer; the mixing amount near the side of the hydrophilic layer is relatively large, the density of network grooves and micropores is high, and the three-dimensional volume is small; the mixing amount near the side of the top surface of the roadbed structure is relatively small, the density of network grooves and micropores is low, and the three-dimensional volume is large, so that the moisture is one-way transmitted from the hydrophobic layer to the hydrophilic layer.

[0013] In a possible implementation manner, the hydrophobic finishing agent is selected from a fluorine-free waterproof agent, and the mixing mass ratio of the fluorine-free waterproof agent is 0.5%-2.0%.

[0014] In a possible implementation manner, the particle size of the graded gravel is 2-10mm.

[0015] The one-way moisture guiding function layer structure of the railway roadbed provided by the present application has the following beneficial effects: 1)When atmospheric precipitation infiltrates through the structural joint of the upper railway ballastless track or the ballast bed, the anti-seepage structure can prevent water from infiltrating and seeping on the top surface of the subgrade structure, and the mechanism is that most of the seepage water flows laterally to the shoulder drainage ditch under the induction of the drainage slope through the large pore structure of the flow guide layer, and a small part of the seepage water flows into the hydrophilic layer, but is blocked on the top surface of the hydrophobic layer due to the one-way moisture guiding effect of the hydrophobic layer, thereby realizing the anti-seepage performance.

[0016] 2)The flow guide layer and the hydrophilic layer can ensure that the discharged water or atmospheric precipitation does not enter the hydrophobic layer and the subgrade, thereby realizing the one-way moisture guiding effect.

[0017] 3)Even if a leakage point occurs to cause the subgrade to be in a water-rich state, after the weather turns fine, the water can be quickly absorbed by the network groove and micropore at the lower part of the hydrophobic layer, and under the capillary and wicking effects, the water quickly migrates upward to the hydrophilic layer, and then volatilizes under the action of air convection of the flow guide layer, thereby shortening the residence time of water in the subgrade.

[0018] The application also provides a design method of a one-way moisture guiding function layer structure of a railway subgrade, which comprises the following steps: S1, collecting meteorological data and railway design conditions of the region where the work site is located to determine the maximum precipitation speed V 1 and the maximum dynamic stress and allowable dynamic deformation of the railway line foundation; S2, calculating the minimum open porosity of the flow guide layer of the permeable concrete n ; the calculation method is the ratio of the maximum precipitation speed V 1 (cm / s) to the rated permeability coefficient of the permeable concrete k (cm / s): n = V 1 / ( k · N ) In the formula, N is a track structure correction coefficient, when the track structure is a ballast track, because the precipitation permeability is high, the value of N is taken as 0.6-0.8, the greater the thickness of the ballast bed and the particle size of the ballast, the smaller the value of N ; when the track structure is a ballastless track, because the precipitation permeability is low, only the joint and the middle of the line have the infiltration path, the value of N is taken as 1.4-1.8, the more the number of joints and the larger the opening size, the smaller the value of N ; S3, calculating the minimum supporting stiffness of the top surface of the anti-seepage structure composed of the flow guide layer, the hydrophilic layer and the hydrophobic layer arranged in turn from top to bottom E min (MPa / m); the calculation method is the maximum dynamic stress of the railway line foundation in step S1σ (kPa) and maximum allowable dynamic deformation m The ratio of (mm), that is E min = σ / m ; S4. Determine the thicknesses of the diffusing layer, hydrophilic layer, and hydrophobic layer respectively, and denote them as follows: h 1. h 2. h 3. The overall thickness of the seepage prevention structure is controlled at 10-15cm. The greater the rainfall, the greater the overall thickness. The thickness of the diversion layer, hydrophilic layer, and hydrophobic layer should be from largest to smallest, with the diversion layer thickness selected as 5-7cm, the hydrophilic layer thickness selected as 3-5cm, and the hydrophobic layer thickness selected as 2-3cm. S5. Draft the component schemes for the permeable concrete of the diversion layer, the hydrophilic modified mortar of the diversion layer, and the hydrophobic modified asphalt concrete of the diffusive layer, respectively. Use uniaxial compression tests to determine their respective deformation moduli, denoted as follows: E 1. E 2. E 3 (MPa); S6. Calculate the design support stiffness of the top surface of the seepage-proof structure. E 0 (MPa / m); the calculation method is as follows:

[0019] in,

[0020]

[0021]

[0022]

[0023] ; S7. The design support stiffness obtained in S6 E Minimum support stiffness obtained from 0 and S3 E min Compare; if E 0≥ E min ,and E If 0 is within the range of 500 to 1000 MPa / m, then the values ​​of the indicators in S4 and S5 are determined as the design scheme; if E 0 < E min Then according to h 1. Increased by 1.0 cm h 2 and h 3. Adjust the gradient by decreasing it by 0.5 cm respectively. h 1.h 2、 h 3 the value of, until E 0 meet the requirements; S8, according to the respective component scheme of the hydrophilic layer modified mortar and the hydrophobic layer modified asphalt concrete determined in S5, the bulk density of each is calculated, and then the recommended mixing mass ratio is determined according to the foregoing, the mixing mass ratio of the hydrophilic finishing agent and the hydrophobic finishing agent is determined to ensure that the hydraulic permeability meets the foregoing requirements.

[0024] The design method of the one-way moisture guiding function layer structure of the railway subgrade provided by the application has the beneficial effects that: 1) a subsidiary structure layer with moisture absorption, moisture guiding and fast drying is designed, the flow direction of water can be controlled, the water in the subgrade is transferred outward, and the external water cannot penetrate into the subgrade, which helps to maintain the long-term service performance of the subgrade; 2) a composite structure that automatically responds to changes in the external environment is designed, and therefore belongs to a functional structure; the one-way moisture guiding is based on the capillary differential effect of material properties and the forced convection effect of air, and does not need external power compensation. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0026] Figure 1 A structure diagram of the one-way moisture guiding function layer structure of the railway subgrade provided by the embodiment of the application is shown in the figure. Figure 2 A cross-sectional schematic diagram of the one-way moisture guiding function layer structure of the railway subgrade and the traffic subgrade structure provided by the embodiment of the application is shown in the figure. Figure 3 A structure diagram of the one-way moisture guiding function layer structure of the railway subgrade provided by the embodiment of the application is shown in the figure. Figure 2 An enlarged view of the structure represented by the dashed box in the figure. Figure 4 A three-dimensional schematic diagram of the one-way moisture guiding function layer structure of the railway subgrade and the traffic subgrade structure provided by the embodiment of the application is shown in the figure.

[0027] Explanation of reference signs: 1, flow guiding layer; 2, hydrophilic layer; 3, hydrophobic layer; 4, subgrade structure; 5, track bed. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0029] Please refer to Figures 1 to 4 , now a one-way wet function layer structure of a railway roadbed provided by the present application will be described. The one-way wet function layer structure of the railway roadbed comprises a flow guide layer 1, a hydrophilic layer 2 and a hydrophobic layer 3 which are sequentially and closely arranged from top to bottom, and the flow guide layer 1, the hydrophilic layer 2 and the hydrophobic layer 3 form a three-layer composite structure; the flow guide layer 1 is used for leading and draining rainwater to the outside of the roadbed and forming a channel for the volatilization and drainage of water in the hydrophilic layer 2; the hydrophilic layer 2 is used for diffusing water; the hydrophobic layer 3 is used for one-way guiding and conveying water to the hydrophilic layer 2; wherein the hydrophobic layer 3 is arranged at the top end of the top surface of the roadbed structure 4, and the flow guide layer 1 is arranged at the bottom end of the bottom surface of the track bed 5.

[0030] The one-way wet function layer structure of the railway roadbed provided by the present application has the following beneficial effects compared with the prior art: 1) When atmospheric precipitation infiltrates through the structure joint of the upper railway ballastless track or the track bed 5, the anti-seepage structure can block the infiltration and infiltration of water on the top surface of the roadbed structure 4, and the mechanism is that most of the infiltrated water flows laterally to the road shoulder drainage ditch under the induction of the drainage slope through the large gap structure of the flow guide layer 1, and at the same time, a small part of the infiltrated water flows into the hydrophilic layer 2, and is blocked on the top surface of the hydrophobic layer 3 due to the one-way wetting effect of the hydrophobic layer 3, thereby realizing the anti-seepage performance.

[0031] 2) The flow guide layer 1 and the hydrophilic layer 2 can ensure that the drained water or atmospheric precipitation does not enter the hydrophobic layer 3 and the roadbed, thereby realizing the one-way wetting effect.

[0032] 3) Even if a leakage point occurs to cause a water-rich state of the roadbed, after the weather turns fine, the water will be quickly absorbed by the network groove and micropore at the lower part of the hydrophobic layer 3, and will be quickly migrated upward to the hydrophilic layer 2 under the capillary and wicking effects, and then volatilized under the action of air convection of the flow guide layer 1, thereby shortening the residence time of water in the roadbed.

[0033] In this embodiment, the width of the flow guide layer 1, the hydrophilic layer 2 and the hydrophobic layer 3 is consistent with the width of the top surface of the roadbed structure 4, and the drainage slope is consistent with the drainage slope arranged on the top surface of the roadbed structure 4, i.e. 2% to 4%.

[0034] The flow guide layer 1, the hydrophilic layer 2 and the hydrophobic layer 3 form a three-layer composite impermeable structure, and the overall thickness of the impermeable structure is 10-15 cm, and the thickness of the flow guide layer 1, the hydrophilic layer 2 and the hydrophobic layer 3 decreases in order, wherein the thickness of the flow guide layer 1 is 5-7 cm, the thickness of the hydrophilic layer 2 is 3-5 cm, and the thickness of the hydrophobic layer 3 is 2-3 cm.

[0035] The hydraulic permeability of the impermeable structure is: the internal gap diameter of the flow guide layer 1 is 5-10 cm, which can form continuous runoff, the runoff coefficient is greater than or equal to 0.7, the water permeability coefficient is greater than or equal to 5 mm / s, the hydrophilic angle of the modified mortar of the hydrophilic layer 2 is less than or equal to 60°, and the hydrophilic angle of the modified asphalt concrete of the hydrophobic layer 3 is 110°-140°.

[0036] The mechanical properties of the impermeable structure are: the dynamic strength of the water permeable concrete of the flow guide layer 1, the modified mortar of the hydrophilic layer 2 and the modified asphalt concrete of the hydrophobic layer 3 is controlled to be greater than 200 kPa, and the deformation modulus is greater than or equal to 80 MPa, 65 MPa and 55 MPa respectively. The support stiffness of the top surface of the impermeable structure is controlled to be 500-1000 MPa / m. The elastic deformation of the impermeable structure under the action of train dynamic load is less than or equal to 0.2 mm, and the long-term cumulative deformation is less than or equal to 2 mm.

[0037] In some embodiments, referring to Figures 1 to 4 , the material of the flow guide layer 1 is water permeable concrete, and the aggregate particle size of the water permeable concrete is 25-35 mm. The water permeable concrete is a mixed material composed of cement, water, cementing material and aggregate of the same particle size, and has a certain void ratio. The water permeable concrete has high strength and good permeability, and the internal gap has air forced convection effect. The functions of the flow guide layer 1 include: 1) when it rains, quickly drain water to the area outside the roadbed, preventing water accumulation; 2) when the weather is sunny, efficiently drain air to become an open air contact layer, which provides a channel for the evaporation of water in the hydrophilic layer 2, so that the water in the hydrophilic layer 2 is quickly evaporated and drained.

[0038] In some embodiments, referring to Figures 1 to 2 , the open porosity of the water permeable concrete is 20%-30%. The open porosity of the water permeable concrete refers to the percentage of the volume of the internal connected and surface connected pores to the total volume of the concrete, which is a key index to determine the durability, permeability and strength of the concrete.

[0039] In some embodiments, referring to Figures 1 to 2 , the material of the hydrophilic layer 2 is modified mortar, which is a mixed material composed of a hydrophilic finishing agent, water and machine-made sand. The composition ratio of each component of the hydrophilic finishing agent, water and machine-made sand of the hydrophilic layer 2 is not limited herein. The function of the hydrophilic layer 2 is: strong hygroscopicity and quick drying, and good water diffusion effect.

[0040] In some embodiments, referring to Figures 1 to 4 , the hydrophilic finishing agent is selected from hydrophilic silicone, and the mass ratio of the hydrophilic silicone is 0.4%-0.6%. The mass ratio of the hydrophilic silicone in the total mass of the modified mortar is a key parameter that determines the performance and economy of the material.

[0041] In some embodiments, referring to Figures 1 to 4 , the material of the hydrophobic layer 3 is modified asphalt concrete, which is a mixture of hydrophobic finishing agent, graded gravel and asphalt. The composition ratio of each component of the hydrophobic finishing agent, graded gravel and asphalt of the hydrophobic layer 3 is not limited herein. The function of the hydrophobic layer 3 is to construct a super-hydrophilic network groove and micro-pore on the internal void boundary of the modified asphalt concrete, and the network groove and micro-pore have a large number and a large irregularity, forming a large number of capillary tubes with wicking effect. Under the action of atmospheric pressure, the water in the water-rich part of the roadbed can quickly move through the grooves and micro-pores.

[0042] In some embodiments, referring to Figures 1 to 4 , the amount of the hydrophobic finishing agent gradually decreases from top to bottom along the thickness direction of the hydrophobic layer 3; the amount of the hydrophobic finishing agent near the hydrophilic layer 2 side is larger, the density of the network groove and micro-pore is higher, and the three-dimensional volume is smaller; the amount of the hydrophobic finishing agent near the top surface of the roadbed structure 4 side is smaller, the density of the network groove and micro-pore is lower, and the three-dimensional volume is larger, so that the water is unidirectionally transported from the hydrophobic layer 3 to the hydrophilic layer 2.

[0043] In some embodiments, referring to Figures 1 to 4 , the hydrophobic finishing agent is selected from a fluorine-free waterproof agent, and the mass ratio of the fluorine-free waterproof agent is 0.5%-2.0%. The fluorine-free waterproof agent is an environmentally friendly auxiliary agent that imparts water-repellent properties to fabrics through non-fluorocarbon chemical structures (such as long-chain alkanes, silicones, and bio-based polymers).

[0044] In some embodiments, referring to Figures 1 to 4 , the particle size of the graded gravel is 2-10 mm.

[0045] The technical principle of the unidirectional moisture guiding of the present application is that the modified mortar of the hydrophilic layer 2 and the modified asphalt concrete of the hydrophobic layer 3 have different moisture absorption and moisture conductivity, and the difference in moisture absorption and the wetting gradient between the hydrophobic layer 3 and the hydrophilic layer 2 are utilized, that is, the lower part of the modified asphalt concrete is mostly hydrophobic, and the upper part of the modified mortar is hydrophilic. When the roadbed is rich in water, the water can be quickly siphoned or wick along the network groove and micro-pore to the inside of the hydrophobic layer 3. Then, under the differential capillary action between the hydrophobic layer 3 and the hydrophilic layer 2, the water in the hydrophobic layer 3 will continue to be quickly conducted to the hydrophilic layer 2, and the wetting area will be expanded in the hydrophilic layer 2, and then the water will be quickly evaporated under the action of air flow of the flow guiding layer 1, that is, the water will not stay in the hydrophobic layer 3.

[0046] This invention also provides a design method for a unidirectional moisture-conducting functional layer structure for railway subgrade, comprising the following steps: S1. Collect and determine meteorological data and railway design conditions for the area where the work site is located, and determine the maximum precipitation rate. V 1. The maximum dynamic stress and allowable dynamic deformation of the railway subgrade foundation; S2. Calculate the minimum open porosity of the permeable concrete in the diversion layer 1. n The calculation method is based on the maximum precipitation velocity. V 1 (cm / s) and the rated permeability coefficient of permeable concrete k The ratio of (cm / s): n = V 1 / ( k · N ) In the formula, N This is a track structure correction factor. When the track structure is a ballasted track, due to its high precipitation infiltration rate, then... N The value is taken as 0.6 to 0.8. The larger the track bed thickness and the ballast particle size, the better. N The smaller the value, the lower the infiltration path. When the track structure is ballastless, due to its low precipitation infiltration rate, there are only infiltration paths between the joints and the track. N The value is taken as 1.4 to 1.8. The more seams and the larger the opening size, the higher the value. N The smaller the value; S3. Calculate the minimum support stiffness of the top surface of the impermeable structure composed of the diversion layer 1, the hydrophilic layer 2, and the hydrophobic layer 3, which are sequentially bonded together from top to bottom. E min (MPa / m); the calculation method is the maximum dynamic stress of the railway subgrade foundation in step S1. σ (kPa) and maximum allowable dynamic deformation m The ratio of (mm), that is E min = σ / m ; S4. Determine the thicknesses of the flow-guiding layer 1, hydrophilic layer 2, and hydrophobic layer 3 respectively, and denote them as follows: h 1. h 2. h 3. The overall thickness of the seepage prevention structure is controlled at 10-15cm. The greater the rainfall, the greater the overall thickness. The thickness of the diversion layer 1, hydrophilic layer 2, and hydrophobic layer 3 decreases from large to small. The thickness of the diversion layer 1 is selected as 5-7cm, the thickness of the hydrophilic layer 2 is selected as 3-5cm, and the thickness of the hydrophobic layer 3 is selected as 2-3cm. S5, respectively, the water permeable concrete of the drainage layer 1, the modified mortar of the hydrophilic layer 2 and the modified asphalt concrete of the hydrophobic layer 3 are prepared, and the uniaxial compression test is used to determine the deformation modulus of each, respectively E 1、 E 2、 E 3 (MPa); S6, the design support stiffness of the top surface of the anti-seepage structure is calculated E 0 (MPa / m); the calculation method is:

[0047] Among them,

[0048]

[0049]

[0050]

[0051] ; S7, the design support stiffness E 0 obtained in S6 and the minimum support stiffness E min are compared; if E 0≥ E min , and E 0 is between 500-1000 MPa / m, then the index value in S4 and S5 is determined as the design scheme; if E 0< E min , then the value of h 1 is increased by 1.0 cm, h 2 and h 3 are respectively reduced by 0.5 cm, and the value of h 1、 h 2、 h 3 is adjusted in gradient until E 0 meets the requirements; S8, according to the component scheme of the modified mortar of the hydrophilic layer 2 and the modified asphalt concrete of the hydrophobic layer 3 determined in S5, the bulk density of each is calculated, and then the recommended addition mass ratio of the hydrophilic finishing agent and the hydrophobic finishing agent is determined according to the foregoing, to ensure that the hydraulic permeability meets the foregoing requirements.

[0052] The design method of the one-way moisture guiding function layer structure of the railway roadbed has the beneficial effects that: 1) a subsidiary structure layer with moisture absorption, moisture guiding and fast drying is designed, the flow direction of water can be controlled, the water in the roadbed is transferred outward, and the external water cannot penetrate into the roadbed, which helps to maintain the long-term service performance of the roadbed; 2) a composite structure which automatically responds to the changes of the external environment is designed, and thus belongs to a functional structure; the one-way moisture guiding is based on the capillary differential effect and air forced convection effect of material properties, and does not need external power compensation.

[0053] The work point refers to a geographical position or engineering node with an independent construction task, and is a specific implementation unit of the project sub-project.

[0054] Maximum precipitation rate V 1 refers to the ratio of the historical maximum precipitation amount to the precipitation duration. The design method is prior art, and will not be described here.

[0055] The application also provides a construction process of the one-way moisture guiding function layer structure of the railway roadbed, and specifically includes the following steps: S1, after the bed surface layer filling construction of the railway roadbed is completed, FZ400 mesh cloth with a height of 40mm is uniformly spread on the top surface of the bed, and a formwork is installed on both sides of the top surface of the bed, wherein the height of the formwork is h 1+ h 2+ h 3. S2, field-mixed modified asphalt concrete is produced, is spread in three layers, and is formed by hot mixing and hot paving; the hydrophobic finishing agent gradually increases when the first layer to the third layer of the modified asphalt concrete is field-mixed and produced, and the mixing amount is respectively taken as 120%, 100% and 80% of the rated mixing amount of the hydrophobic finishing agent in the design method; S3, after the hydrophobic layer 3 is spread and compacted, maintenance is carried out, water is sprayed for cooling at regular intervals, and the hydrophobic layer 3 is naturally dried for more than 2 days, so that the surface of the hydrophobic layer 3 is kept flat and clean; S4, field-mixed modified mortar is produced and is formed once; a troweling construction process is adopted, a glass fiber mesh cloth with a mesh size of 5*5mm is pressed into the modified mortar, and is leveled, and the mesh cloth at the joint should be overlapped; S5, after the hydrophilic layer 2 is troweled, wet cloth covering is used for maintenance, and the maintenance time is more than 7 days; S6, field-mixed pervious concrete is produced and is formed once, and after leveling and edge collecting, a film is covered for maintenance, and the maintenance time is more than 14 days.

[0056] The one-way moisture guiding function layer structure is adopted in the application, and compared with the prior art, the progress is that: 1) From the implementation effect point of view, the embankment unidirectional moisture guide anti-seepage structure is a kind of auxiliary structure layer with moisture absorption, moisture guide and fast drying. It can control the flow direction of water, achieve the purpose of water transfer from the inside to the outside of the embankment, and prevent external water from seeping into the inside of the embankment, which helps to maintain the long-term service performance of the embankment.

[0057] 2) From the functional principle point of view, the proposed unidirectional moisture guide anti-seepage structure is a composite structure that automatically responds to changes in the external environment (atmospheric precipitation seeps into the embankment, making the filler in a water-rich state) by automatically draining the accumulated water in the embankment to the outside of the embankment. Therefore, it belongs to a functional structure. The unidirectional transport of water is based on the capillary differential effect and air forced convection effect of material properties, without the need for external power compensation. The unidirectional transport process of water is as follows: first, use the capillary differential effect principle of the internal hydrophobic layer 3 and the middle hydrophilic layer 2, the internal hydrophobic layer 3 is responsible for quickly conducting water from the embankment to the middle hydrophilic layer 2, keeping the embankment dry. Then, use the air forced convection effect of the external flow guide layer 1 to quickly evaporate the water.

[0058] 3) From the implementation process point of view, the unidirectional moisture guide layer structure adopts a composite three-layer structure, and the fillers of the flow guide layer 1, the hydrophilic layer 2 and the hydrophobic layer 3 are water permeable concrete, modified mortar and modified asphalt concrete respectively. First, the preparation process of the filler is mature and can be mixed on site; second, the construction process of the filler is mature, and the mechanization degree of the construction links such as paving and compaction is high and the technology is reliable; third, the hydrophilic finishing agent and the hydrophobic finishing agent used have been large-scale industrialized in the field of industrial and civil buildings, which is convenient to introduce into the field of railway engineering; 4) From the matching point of view with the conventional embankment, the road performance of water permeable concrete, modified mortar and modified asphalt concrete fillers is stable, and the adjustable range of mechanical performance indicators and hydraulic permeability performance indicators is large, which is convenient for adaptive selection of component schemes. At the same time, a design method is proposed for different regional meteorological conditions and railway engineering conditions, which can meet the requirements of water drainage under the most unfavorable conditions and deformation control of railway line foundation, while playing the role of unidirectional moisture guide, it can also buffer the dynamic load conditions of the embankment, neutralize the stiffness difference between the concrete base plate of the ballastless track and the embankment soil filler, and improve the dynamic deformation and long-term cumulative deformation state of the embankment.

[0059] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A one-way moisture conducting function layer structure of a railway subgrade, characterized by, The three-layer composite structure comprises a water-diversion layer, a hydrophilic layer and a hydrophobic layer arranged in sequence from top to bottom; the water-diversion layer is used to divert rainwater to the outside of the roadbed and form a channel for the evaporation of water in the hydrophilic layer; the hydrophilic layer is used to diffuse water; and the hydrophobic layer is used to unidirectionally guide and send water to the hydrophilic layer. The water-diversion layer is arranged at the upper end of the top surface of the roadbed structure, and the hydrophobic layer is arranged at the lower end of the bottom surface of the track bed.

2. A one-way moisture conducting function layer structure of a railway bed as set forth in claim 1, wherein The water-diversion layer is made of water-permeable concrete, and the aggregate particle size of the water-permeable concrete is 25-35 mm.

3. A one-way moisture conducting function layer structure of a railway bed as set forth in claim 2, wherein The water-permeable concrete has an open porosity of 20-30%.

4. The one-way moisture conducting function layer structure of a railway bed as recited in claim 1, wherein, The hydrophilic layer is made of modified mortar, which is a mixture of a hydrophilic finishing agent, water and machine-made sand.

5. A one-way moisture conducting function layer structure of a railway bed as defined in claim 4, wherein The hydrophilic finishing agent is selected from hydrophilic organic silicon, and the mixing mass ratio of the hydrophilic organic silicon is 0.4-0.6%.

6. A one-way moisture conducting function layer structure of a railway bed as defined in claim 1, wherein The hydrophobic layer is made of modified asphalt concrete, which is a mixture of a hydrophobic finishing agent, graded gravel and asphalt.

7. A one-way moisture conducting function layer structure of a railway bed as defined in claim 6, wherein The mixing amount of the hydrophobic finishing agent gradually decreases from top to bottom along the thickness direction of the hydrophobic layer; the mixing amount near the hydrophilic layer side is larger, the density of network grooves and micropores is higher, and the three-dimensional volume is smaller; the mixing amount near the top surface of the roadbed structure is smaller, the density of network grooves and micropores is lower, and the three-dimensional volume is larger, so that water is unidirectionally transmitted from the hydrophobic layer to the hydrophilic layer.

8. A one-way moisture conducting function layer structure of a railway bed as defined in claim 6, wherein The hydrophobic finishing agent is selected from a fluorine-free waterproof agent, and the mixing mass ratio of the fluorine-free waterproof agent is 0.5-2.0%.

9. A one-way moisture conducting function layer structure of a railway bed as defined in claim 6, wherein The particle size of the graded gravel is 2-10 mm.

10. A method of designing a one-way moisture conducting function layer structure of a railway subgrade, characterized in that, The method comprises the following steps: S1, collect meteorological data and railway design conditions of the area where the work point is located, and determine the maximum precipitation speed V 1 and the maximum dynamic stress and allowable dynamic deformation of the railway line foundation; S2, calculating the minimum open porosity of the pervious concrete of the drainage layer n ; The calculation method is the ratio of the maximum precipitation rate V 1 (cm / s) to the nominal permeability coefficient of the pervious concrete k (cm / s). n = V 1 / ( k · N ) In the formula, N is a track structure correction coefficient, when the track structure is a ballast track, because its rainfall infiltration rate is high, then N The value is 0.6-0.8, the thicker the ballast bed and the larger the ballast particle size, N The value is smaller; when the track structure is a non-ballast track, because its rainfall infiltration rate is low, only in the joint and the middle of the line has a penetration path, then N The value is 1.4-1.8, the more the number of joints and the larger the opening size, N The value is smaller; S3, calculating the minimum support stiffness of the top surface of the anti-seepage structure composed of the diversion layer, the hydrophilic layer and the hydrophobic layer arranged in turn from top to bottom E min (MPa / m); the calculation method is the maximum dynamic stress of the foundation under the railway line in step S1 The method comprises the following steps: (kPa) and the maximum allowable dynamic deformation m (mm), that is E min = S8, according to the component schemes of the hydrophilic layer modified mortar and the hydrophobic layer modified asphalt concrete determined in S5, the bulk densities of the two are calculated, and then the mixing mass ratios of the hydrophilic finishing agent and the hydrophobic finishing agent are determined according to the recommended mixing mass ratios, so as to ensure that the hydraulic permeability meets the requirements. / m ; S4, the thickness of the diversion layer, the hydrophilic layer and the hydrophobic layer are respectively determined, and are respectively denoted as h 1, h 2, h 3; the overall thickness of the anti-seepage structure is controlled to be 10-15 cm, the greater the rainfall is, the greater the overall thickness is; the thickness of the diversion layer, the hydrophilic layer and the hydrophobic layer is selected to be from large to small, wherein the thickness of the diversion layer is selected to be 5-7 cm, the thickness of the hydrophilic layer is selected to be 3-5 cm, and the thickness of the hydrophobic layer is selected to be 2-3 cm; S5, respectively, the water permeable layer of the concrete, the hydrophilic layer of the modified mortar and the hydrophobic layer of the modified asphalt concrete of each component scheme, using uniaxial compression test, the deformation modulus of each is recorded as E 1、 E 2、 E 3 (MPa); S6、Calculate the design support stiffness of the top surface of the anti-seepage structure E 0 (MPa / m); the calculation method is: wherein ； S7, the design support stiffness obtained from S6 E 0 and the minimum support stiffness obtained from S3 E min comparison; if E 0≥ E min , and E 0 is between 500-1000 MPa / m, the index value in S4 and S5 is determined as the design scheme; if E 0< E min , the value of h 1 is increased by 1.0 cm, h 2 and h 3 are respectively reduced by 0.5 cm in gradient adjustment h 1, h 2, h 3 until E 0 meets the requirements; ​

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