Method and structure for preventing moisture accumulation of roadbed and method for calculating heating temperature

Abstract

The invention relates to the technical field of permafrost region subgrade protection, and discloses a subgrade moisture accumulation prevention method and structure and a heating temperature calculation method.The heating temperature calculation comprises the steps that the sum of evaporation power and precipitation difference values of months with the monthly average temperature larger than 0 DEG C is obtained; obtaining a first daily water seepage amount; calculating to obtain surface evaporation loss according to the month with the monthly average temperature greater than 0 DEG C, the sum of the difference values of the evaporation power and the precipitation, the first daily water seepage amount and parameters of the moisture accumulation prevention structure, and calculating to obtain saturated vapor pressure for heating the surface of the drainage ditch in the moisture accumulation prevention structure according to the surface evaporation loss; and calculating the heating temperature by using the saturated vapor pressure. By collecting, blocking and evaporating freeze-thaw water on the mountainside or the slope side, the water accumulation prevention structure relieves the problem of serious water accumulation on the roadside, guarantees the road stability, prevents roadbed diseases, prolongs the service life of the road, and assists high-quality construction of road engineering in cold regions.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed protection in frozen soil areas, and in particular to a method and structure for preventing moisture accumulation in a roadbed and a method for calculating a heating temperature. Background Art

[0002] The extreme climatic conditions of the Qinghai-Tibet Plateau, especially factors such as low temperature, high frequency of freeze-thaw and strong ultraviolet radiation, pose great challenges to highway construction and operation in frozen soil environments. Highway construction has changed the original topography, blocked the original surface drainage system, cut off the natural drainage channel, and caused water to accumulate in local areas; at the same time, the strong heat absorption characteristics of the highway asphalt pavement have caused the upper limit of the permafrost zone to continue to decline, and the meltwater inside the roadbed has increased, further exacerbating the water accumulation effect. Especially in the warm season, the problem of roadside water accumulation on highways is particularly serious, especially on the mountainside or slope side sections. The snow meltwater, groundwater and freeze-thaw water on the hillside are more likely to accumulate on the roadside, making the roadbed water accumulation phenomenon more prominent. On the one hand, the accumulation of water on the roadside of the mountainside or slope side of the permafrost area will enhance the freeze-thaw cycle and aggravate the frost heave and thaw settlement caused by it; on the other hand, water and heat migration will accelerate the degradation of permafrost, and eventually cause roadbed settlement, cracks, waves and other diseases. Therefore, effective measures must be taken to control the problem of water accumulation on the roadside in permafrost areas to reduce the damage of water accumulation to the roadbed.

[0003] The current "Highway Drainage Design Code" (JTG / T D33-2012) uses water retaining embankments and drainage berms to intercept or squeeze out the hillside water from the roadbed, but does not actually remove the water flow and eliminate its impact. The harm caused by water accumulation still exists. Patent document CN115807367A discloses a solar-heated seasonal anti-freeze heave drainage roadbed and its construction method, and proposes a composite roadbed drainage method with a heating and moisture-absorbing geotextile inside the roadbed; Patent document CN113026462A discloses a temperature control structure suitable for roadbed and slope engineering in permafrost areas. Both focus on drainage inside the roadbed, and cannot effectively solve the problem of frozen-thaw water accumulation on the roadside in warm seasons, and neither calculates and evaluates the drainage effect.

[0004] At present, in order to solve the problem of freeze-thaw water accumulation on the roadside of the mountainside or slope side of the roadbed in the permafrost area in the warm season, an anti-moisture accumulation structure is set on the mountainside or slope side of the roadbed in the permafrost area. The freeze-thaw water of the active layer in the permafrost area in the warm season is partially collected in the anti-moisture accumulation structure, and the anti-moisture accumulation structure is heated to evaporate the accumulated water. This is an effective treatment method, but the prior art does not yet know how to calculate the heating temperature of the anti-moisture accumulation structure to achieve effective evaporation of the accumulated water. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that there is no method for calculating the heating temperature when heating and evaporating the accumulated water on the roadside of the roadbed in the prior art, and to provide a method and structure for preventing water accumulation on the roadbed and a method for calculating the heating temperature.

[0006] In a first aspect, the present invention provides a method for calculating the heating temperature of a roadbed water accumulation prevention structure, comprising the following steps: Obtain the sum of the differences between evaporation and precipitation in the months with a monthly average temperature greater than 0°C and the months with a monthly average temperature greater than 0°C throughout the year; Obtaining a first daily water seepage amount, where the first daily water seepage amount is the water seepage amount of water entering the moisture accumulating structure; According to the months with average monthly temperature greater than 0℃, the sum of the difference between evaporation power and precipitation, the first daily seepage volume, and the parameters of the moisture-proof accumulation structure, the surface evaporation loss of the moisture-proof accumulation structure is calculated. The calculation formula for the surface evaporation loss is:

[0007] Where H is the surface evaporation loss, unit is mm / d, Q 1 is the first daily seepage volume, in m 3 / d, B 1 is the average width of the heating drainage ditch in the water accumulation prevention structure, in meters. It is the length of the water collection along the length of the heating drainage ditch in the structure to prevent moisture accumulation, in meters. is the number of months with a monthly average temperature greater than 0°C, c It is the sum of the difference between evaporation and precipitation in the months with an average monthly temperature greater than 0℃ throughout the year, in mm; The saturated vapor pressure on the surface of the heating drainage ditch in the anti-water accumulation structure is calculated based on the surface evaporation loss, and the heating temperature is calculated using the saturated vapor pressure. The calculation formula for the heating temperature is:

[0008] In the formula T The heating temperature of the surface of the heated drain in the structure to prevent moisture accumulation, in °C, P m is the saturated vapor pressure, in Pa, A, B, C is the Antoine constant.

[0009] In the above technical solution, by obtaining the sum of the difference between the evaporation power and precipitation in the months with a monthly average temperature greater than 0°C and the months with a monthly average temperature greater than 0°C throughout the year, and the first daily infiltration volume of water entering the moisture-proof accumulation structure, the water entering the moisture-proof accumulation structure includes water that converges from the active layer in the permafrost area to the moisture-proof accumulation structure, and combining the data to calculate the surface evaporation loss through the moisture-proof accumulation structure, the saturated vapor pressure of the surface of the heating drainage ditch in the moisture-proof accumulation structure is calculated by the surface evaporation loss, and the heating temperature is calculated by the saturated vapor pressure. When the moisture-proof accumulation structure is set on the mountain side or slope side of the roadbed, the above technical solution of the present invention is adopted to quickly and accurately calculate the heating temperature of the moisture-proof accumulation structure, which is used to evaporate the accumulated water by heating, effectively solving the problem of the accumulation of freeze-thaw water on the roadside in the warm season in the permafrost area, and avoiding the damage to the roadbed caused by water accumulation.

[0010] As a preferred embodiment of the present invention, the method for obtaining the sum of the difference between evaporation power and precipitation is: Step S11, based on the meteorological data of the permafrost region, counting the months with an average monthly temperature greater than 0°C throughout the year; Step S12, obtaining monthly evaporation power and monthly precipitation data for months when the monthly average temperature is greater than 0°C; Step S13, the total difference between the evaporation power and the precipitation for the whole year is calculated based on the monthly evaporation power and the monthly precipitation data. The calculation formula for the total difference between the evaporation power and the precipitation is:

[0011] in PE i is the monthly evaporation power, in mm, P i is the monthly precipitation in mm, is the number of months with average monthly temperature greater than 0℃.

[0012] As a preferred embodiment of the present invention, the method for obtaining the first daily water seepage volume is: Step S21, based on the stratum and hydrological data of the permafrost area, obtaining the first soil layer permeability coefficient and the first soil layer hydraulic gradient of the active layer for water to enter the anti-water accumulation structure; Step S22, based on the permeability coefficient of the first soil layer and the hydraulic gradient of the first soil layer, the first daily water seepage amount of water entering the moisture-proof accumulation structure is calculated. The calculation formula of the first daily water seepage amount is:

[0013] In the formula, is the permeability coefficient of the first soil layer, is the hydraulic gradient of the first soil layer, is the cross-sectional area of ​​water flow,A 1= h 1× L , in square meters 。

[0014] As a preferred embodiment of the present invention, the calculation formula for the average width of the heating drainage ditch is:

[0015] In the formula B 0 is the bottom width of the heating drainage ditch, α It is the inverse of the slope of the left side of the heating drainage ditch. β It is the inverse of the slope of the right side of the heating drainage ditch.

[0016] As a preferred embodiment of the present invention, the calculation formula of saturated vapor pressure is:

[0017] in P is the relevant air pressure value, in Pa; V m Indicates the daily average wind speed in m / s.

[0018] In a second aspect, the present invention provides a method for preventing moisture accumulation in a roadbed on a mountain side or a slope side in a permafrost region, wherein a moisture accumulation structure is arranged on the mountain side or the slope side of the roadbed, wherein a heating drainage ditch is arranged in the moisture accumulation structure, and a water-permeable layer is arranged on the side of the moisture accumulation structure away from the roadbed, so as to collect moisture in the permafrost region into the heating drainage ditch; an electric heating film is arranged on the side of the moisture accumulation structure close to the roadbed, so as to heat the heating drainage ditch; The method includes monitoring the temperature and relative humidity at the bottom of the heated drain; When the temperature at the bottom of the heating drain ditch is ≥0°C and the relative humidity is ≥60%, the electric heating film is started for heating so that the temperature at the bottom of the heating drain ditch reaches the heating temperature calculated by the above method; The heating drain ditch is maintained in a constant temperature heating state to heat and evaporate the water until the relative humidity at the bottom of the heating drain ditch is less than 60%, and then the heating is stopped.

[0019] In the above technical scheme, an anti-water accumulation structure is arranged on the mountain side or slope side of the roadbed, and a permeable layer is arranged on the side away from the roadbed. Melted snowwater, rainwater and subsurface freeze-thaw water on the mountain side or slope side flow into the heating drain ditch through the permeable layer, and the heating drain ditch is heated and evaporated by an electric heating film close to the roadbed. When it is monitored that the temperature at the bottom of the heating drain ditch is ≥0°C and the relative humidity is ≥60%, the electric heating film is started for heating so that the temperature at the bottom of the heating drain ditch reaches the heating temperature calculated by the above method, which can effectively deal with the accumulated water on the roadbed and prevent the damage to the roadbed caused by moisture accumulation.

[0020] As a preferred embodiment of the present invention, the electric heating film is selected from at least one of a graphene electric heating film, a silicone electric heating film or a carbon fiber heating film.

[0021] As a preferred embodiment of the present invention, the electric heating film meets the requirements of waterproof grade ≥ IPX8, thickness ≥ 0.25 mm, power density 80~200 W / m 2 , electrothermal conversion efficiency ≥ 60%, heating uniformity ≤ ± 5 ° C. Preferably, the thickness of the electric heating film is 0.25~0.6mm, and the power density is 100W / m 2 or 150W / m 2 .

[0022] In a third aspect, the present invention provides a moisture-proof accumulation structure for a roadbed on a mountain side or a slope side in a permafrost region, the moisture-proof accumulation structure comprising a water-permeable layer and a heating layer, the water-permeable layer being arranged on the side away from the roadbed, the heating layer being arranged on the side close to the roadbed, turf being arranged on the water-permeable layer and the heating layer, the heating layer comprising an electric heating film, a heat insulating layer and a waterproof layer arranged from top to bottom; the water-permeable layer and the heating layer enclose a semi-open heating drainage ditch, and a temperature sensor and a humidity sensor are arranged at the bottom of the heating drainage ditch corresponding to the heating layer.

[0023] As a preferred embodiment of the present invention, the cross-section of the moisture-proof accumulation structure is an inverted trapezoidal structure, the cross-section of the heating drainage ditch is an inverted trapezoidal structure, the two sides of the moisture-proof accumulation structure are respectively the first surface and the third surface, the bottom is the second surface, the second surface connects the first surface and the third surface, the first surface is far away from the roadbed, and the third surface is close to the roadbed, the permeable layer is arranged on the first surface, and the heating layer is arranged on the second surface and the third surface, the slope of the first surface is not greater than 1:2, and the slope of the third surface is not greater than 1:1.

[0024] As a preferred embodiment of the present invention, the permeable layer includes a filter layer and a permeable membrane layer arranged in sequence, the filter layer includes a coarse sand layer, a medium sand layer, and a fine sand layer arranged in sequence, and the coarse sand layer is arranged away from the roadbed; the thickness of the coarse sand layer is 8~30cm, the thickness of the medium sand layer is 10~20cm, the thickness of the fine sand layer is 10~20cm, the particle size of the gravel in the coarse sand layer is 5~20mm, the particle size of the gravel in the medium sand layer is 1~5mm, and the particle size of the gravel in the fine sand layer is 0.25~1mm.

[0025] As a preferred solution of the present invention, the electric heating film is powered by a solar energy storage system, which includes a solar panel, an energy storage device, a controller, and an inverter.

[0026] As a preferred embodiment of the present invention, the height between the bottom of the heating drainage ditch and the upper limit of the permafrost is a limited height, and the method for determining the limited height is: The second daily water seepage is calculated based on the sum of the difference between the evaporation power and precipitation in the months with an average monthly temperature greater than 0°C and the parameters of the water-proof water accumulation structure. The second daily water seepage is the water seepage in the active layer of the permafrost area that does not enter the water-proof water accumulation structure. The calculation formula for the second daily water seepage is:

[0027] in is the daily second water volume, in m 3 / d, l is the distance between the heating drainage ditch and the toe of the roadbed, in meters; Based on the geological data of permafrost areas, the permeability coefficient of the second soil layer and the hydraulic gradient of the second soil layer are obtained so that water does not enter the active layer of the anti-water accumulation structure; The limited height is calculated using the second soil layer permeability coefficient, the second soil layer hydraulic gradient, and the second daily seepage volume. The calculation formula for the limited height is:

[0028] in To limit the height, the unit is mm, is the hydraulic gradient of the second soil layer, is the permeability coefficient of the second soil layer.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for calculating the heating temperature of a roadbed moisture accumulation structure. The method obtains the sum of the difference between the evaporation power and precipitation in the months with a monthly average temperature greater than 0°C and the months with a monthly average temperature greater than 0°C throughout the year, and the first daily water seepage volume, and combines the data to calculate the surface evaporation loss of the moisture accumulation structure for evaporation. The saturated vapor pressure of the surface of the heated drainage ditch in the moisture accumulation structure is calculated by the surface evaporation loss, and the heating temperature is calculated by the saturated vapor pressure. When a moisture accumulation structure is set on the mountain side or slope side of the roadbed, the above-mentioned technical solution of the present invention can be used to quickly and accurately calculate the heating temperature of the moisture accumulation structure, which is used to evaporate the accumulated water by heating, effectively solving the problem of the accumulation of freeze-thaw water on the roadside in the warm season in permafrost areas, and avoiding the damage to the roadbed caused by water accumulation.

[0030] 2. The present invention provides a moisture-proofing structure for the roadbed on the mountain side or slope side in a permafrost area. The moisture-proofing structure is arranged on the mountain side or slope side of the roadbed, and a heating drainage ditch is arranged in the moisture-proofing structure. A permeable layer is arranged in the moisture-proofing structure away from the roadbed, which is used to discharge the moisture in the permafrost area to the heating drainage ditch and collect freeze-thaw water on the mountain side or slope side in the warm season; an electric heating film is arranged near the roadbed in the moisture-proofing structure, which is impermeable and used to heat and evaporate the heating drainage ditch, prevent freeze-thaw water from continuing to flow to the roadbed, heat and evaporate the collected water, and prevent heat from being transferred downward to disturb the permafrost, thereby forming an effective water accumulation treatment system. The water accumulation problem is not solved from the source.

[0031] 3. The present invention aims to solve the problem of serious water accumulation on the roadside of existing permafrost areas, which leads to frequent frost heave and thaw diseases of the roadbed, causing roadbed subsidence, cracks, waves and other diseases. By collecting, blocking and evaporating freeze-thaw water on the mountainside or slope side, the present invention can alleviate the serious problem of water accumulation on the roadside, ensure road stability, prevent roadbed diseases, extend the service life of the road, and contribute to the high-quality construction of road projects in cold regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow chart of a method for calculating the heating temperature of a roadbed moisture accumulation structure according to the present invention; Figure 2 This is a structural diagram of the moisture-proof accumulation structure of the roadbed on the mountain side or slope side in the permafrost region of Example 2; Figure 3 This is a structural diagram of the permeable layer in the water-proof accumulation structure of the roadbed on the mountain side or slope side in the permafrost region of Example 2; Figure 4 This is a structural diagram of the heating layer in the water-proof water accumulation structure of the roadbed on the mountain side or slope side in the permafrost region of Example 2; Markings in the figure: 1- Roadbed, 21-first active layer, 22-second active layer, 23-upper limit of permafrost, 24-active layer boundary, 3-permeable layer, 31-coarse sand layer, 32-medium sand layer, 33-fine sand layer, 34-permeable membrane layer, 4-turf, 5-heated gutter, 6-heating layer, 61-electric heating membrane, 62-insulation layer, 63-waterproof layer. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with specific embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0034] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0035] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0036] In addition, the expressions “first”, “second”, “third”, etc., which appear in the terms, are merely used to distinguish the description of the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0037] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0038] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0039] Example 1 This embodiment provides a method for calculating the heating temperature of a roadbed water accumulation structure. Figure 1 As shown, the following steps are included: Step S1, obtaining the sum of the difference between evaporation power and precipitation in the months with a monthly average temperature greater than 0°C and the months with a monthly average temperature greater than 0°C throughout the year; In step S1, the method for obtaining the sum of the difference between evaporation power and precipitation is: Step S11, based on the meteorological data of the permafrost region, counting the months with an average monthly temperature greater than 0°C throughout the year; Step S12, obtaining monthly evaporation power and monthly precipitation data for months when the monthly average temperature is greater than 0°C; Step S13, the total difference between the evaporation power and the precipitation for the whole year is calculated based on the monthly evaporation power and the monthly precipitation data. The calculation formula for the total difference between the evaporation power and the precipitation is:

[0040] in PE i is the monthly evaporation power, in mm, P i is the monthly precipitation in mm, is the number of months with a monthly average temperature greater than 0°C. c， like c A negative value does not allow meltwater to penetrate.

[0041] Step S2, obtaining a first daily water seepage amount, where the first daily water seepage amount is the water seepage amount of water entering the moisture absorbing structure, and the water entering the moisture absorbing structure includes water gathered from the active layer of the permafrost region into the moisture absorbing structure; In step S2, the method for obtaining the first daily water seepage volume is: Step S21, based on the stratum and hydrological data of the permafrost area, obtaining the first soil layer permeability coefficient and the first soil layer hydraulic gradient of the active layer for water to enter the anti-water accumulation structure; Step S22, based on the permeability coefficient of the first soil layer and the hydraulic gradient of the first soil layer, the first daily water seepage amount of water entering the moisture-proof accumulation structure is calculated. The calculation formula of the first daily water seepage amount is:

[0042] In the formula, is the permeability coefficient of the first soil layer, is the hydraulic gradient of the first soil layer, is the cross-sectional area of ​​water flow, A 1= h 1× L , in square meters, h 1 is the water-passing height of the anti-water accumulation structure, in meters. L To prevent the water collection length of the heated drainage ditch along the length of the ditch in the moisture accumulation structure, that is, the longitudinal length of the heated drainage ditch. The order of the above steps S1 and S2 can be exchanged or performed simultaneously.

[0043] Step S3, according to the months with a monthly average temperature greater than 0°C, the sum of the difference between the evaporation power and the precipitation, the first daily water seepage, and the parameters of the moisture-proof accumulation structure, the surface evaporation loss of the moisture-proof accumulation structure is calculated. The calculation formula of the surface evaporation loss is:

[0044] Where H is the surface evaporation loss, the unit is mm / d or L / (d·m 2 ), mm / d=L / (d·m 2 ), Q 1 is the first daily seepage volume, in m 3 / d, B 1 is the average width of the heating drainage ditch in the water accumulation prevention structure, in meters. It is the length of the water collection along the length of the heating drainage ditch in the structure to prevent moisture accumulation, in meters. is the number of months with a monthly average temperature greater than 0°C, c It is the sum of the difference between evaporation power and precipitation in the months with an average monthly temperature greater than 0℃, in mm. The active layer refers to the near-surface layer above the permafrost layer in the permafrost area, which melts in the warm season and completely refreezes in the cold season within a certain depth below the surface. Part of the water in the active layer is collected in the water-proof accumulation structure for heating and evaporation, and part of it evaporates naturally from the infiltration roadbed at the bottom of the water-proof accumulation structure.

[0045] The calculation formula for the average width of the heating drainage ditch is:

[0046] In the formula B 0 is the bottom width of the heating drainage ditch, α It is the inverse of the slope of the left side of the heating drainage ditch. β It is the inverse of the slope of the right side of the heating drainage ditch.

[0047] Step S4: Calculate the saturated vapor pressure on the surface of the heating drain ditch in the moisture-preventing structure based on the surface evaporation loss, and calculate the heating temperature using the saturated vapor pressure. The calculation formula for the saturated vapor pressure is:

[0048] in P m is the saturated vapor pressure calculated according to the surface temperature of the heated drain, in Pa; P is the air pressure value, measured by a barometer, in Pa; V m Indicates the daily average wind speed in m / s.

[0049] The calculation formula for heating temperature is:

[0050] In the formula T To prevent moisture accumulation in the structure, the heating temperature of the drainage ditch surface is in °C, that is, the control temperature. A, B, C is the Antoine constant, which can be found in the Antoine constant manual.

[0051] Example 2 The present embodiment provides a moisture-proof accumulation structure for a roadbed on a mountain side or a slope side in a permafrost region, the moisture-proof accumulation structure comprising a water-permeable layer 3 and a heating layer 6, the water-permeable layer 3 being arranged close to the roadbed 1, the heating layer 6 being arranged away from the roadbed 1, turf 4 being arranged on the water-permeable layer 3 and the heating layer 6, the heating layer 6 comprising an electric heating film 61, a heat insulating layer 62 and a waterproof layer 63 arranged from top to bottom; the water-permeable layer 3 and the heating layer 6 enclose a semi-open heating drainage ditch 5, and a temperature sensor and a humidity sensor are arranged at the bottom of the heating drainage ditch 5 corresponding to the heating layer 6.

[0052] like Figure 2-4As can be seen from the figure, the moisture-proof accumulation structure is set on the roadbed 1 in the permafrost area. The active layer refers to the near-surface layer above the permafrost layer in the permafrost area and within a certain depth below the surface, which melts in the warm season and completely freezes in the cold season. The permafrost upper limit 23 is between the active layer and the permafrost layer. The soil layer of the active layer will melt in the warm season. The active layer is divided into a first active layer 21 and a second active layer 22 by an active layer boundary 24. The water in the first active layer 21 will be collected along the hillside into the heating drainage ditch 5 of the moisture-proof accumulation structure. The seepage amount of this part of water is the first daily seepage amount. The water in the second active layer 22 infiltrates into the roadbed from the bottom of the moisture-proof accumulation structure. The daily seepage amount of the active layer is , , is the first daily seepage of the first active layer, is the second daily seepage volume of the second active layer; the upper limit of permafrost 23 can be determined by exploration and drilling, by analyzing the characteristics of soil layers at different depths in the borehole, to determine the upper limit of permafrost, and can also be determined based on ground temperature observations.

[0053] In this embodiment, the cross section of the moisture-proof accumulation structure is an inverted trapezoidal structure. Since the water-permeable layer 3 and the heating layer 6 enclose a semi-open heating drainage ditch 5, the cross section of the heating drainage ditch 5 is also an inverted trapezoidal structure. The two sides of the moisture-proof accumulation structure are the first surface and the third surface, respectively, and the bottom is the second surface. The second surface connects the first surface and the third surface. The first surface is far away from the roadbed 1, and the third surface is close to the roadbed 1. The water-permeable layer 3 is arranged on the first surface, and the heating layer 6 is arranged on the second surface and the third surface. In this embodiment, the slope of the first surface is not greater than 1:2, and the slope of the third surface is not greater than 1:1.

[0054] The permeable layer 3 includes a filter layer and a permeable membrane layer 34 which are arranged in sequence. The filter layer includes a coarse sand layer 31, a medium sand layer 32, and a fine sand layer 33. The coarse sand layer 31 is arranged away from the roadbed 1, and the fine sand layer 33 is arranged adjacent to the permeable membrane layer 34. The setting of the filter layer has a filtering function and sufficient water permeability, which can effectively intercept pollutants and reduce the concentration of pollutants in the runoff. The permeable layer 3 is arranged near the side of the moisture accumulation structure to achieve effective drainage. Its main purpose is to promote the rapid discharge of water and prevent water from accumulating near the roadbed 1, thereby protecting the stability and durability of the roadbed 1. The thickness of the coarse sand layer 31 is 8~30cm, the thickness of the medium sand layer 32 is 10~20cm, and the thickness of the fine sand layer 33 is 10~20cm. The particle size of the gravel in the coarse sand layer 31 is 5~20mm, the particle size of the gravel in the medium sand layer 32 is 1~5mm, and the particle size of the gravel in the fine sand layer 33 is 0.25~1mm. In this embodiment, the thickness of the coarse sand layer 31 is 20 cm, the thickness of the medium sand layer 32 is 15 cm, and the thickness of the fine sand layer 33 is 15 cm. The permeable membrane layer 34 is a permeable geotextile, and the permeable membrane layer 34 meets the following requirements: unit area mass ≥ 400 g / m², tensile strength ≥ 20 N / m, elongation at break ≥ 50%, CBR bursting strength ≥ 3.5 KN, tearing strength ≥ 0.56 KN, vertical permeability coefficient 1×10 -1 ~1×10 -2 The permeable geotextile is overlapped on the heating layer 6, and the overlap length is not more than 30 cm.

[0055] In this embodiment, a leveling layer is further provided between the heating layer 6 and the soil layer. The leveling layer is paved with fine sand. The insulation layer 62 can reduce the influence of the heating layer 6 on the temperature of the soil layer. The waterproof layer 63 is a composite geotextile. The waterproof layer 63 meets the following requirements: mass per unit area ≥ 400g / m², thickness ≥ 0.5mm, tensile strength ≥ 20N / m, elongation at break ≥ 50%, tear strength ≥ 0.15KN, and hydrostatic pressure resistance ≥ 0.6MPa / m.

[0056] In some embodiments, the electric heating film 61 is powered by a solar energy storage system, which includes solar panels, energy storage devices, controllers, inverters, etc. The solar panels convert solar energy into electrical energy and store the excess in the energy storage devices. Common energy storage devices include lithium-ion batteries, lithium iron phosphate batteries, and lead-acid batteries. The controller is responsible for managing the charging process of the solar panels to ensure that the batteries are not overcharged or over-discharged, and monitors the status of the batteries to protect the batteries from damage. At the same time, the inverter converts the direct current generated by the solar panels into alternating current to meet the power needs of equipment such as the electric heating film 61: during the day, the solar panels receive sunlight and convert it into electrical energy. Part of the electrical energy directly powers loads such as the electric heating film 61 to meet real-time power needs; the other part of the excess electrical energy is transmitted to the energy storage device through the controller for storage; at night or on cloudy days when there is insufficient light, the electrical energy in the energy storage device is converted into alternating current through the inverter to power loads such as the electric heating film 61 to ensure continuous and stable operation of the system.

[0057] In some other embodiments, the moisture accumulation prevention structure is further provided with a leakage protection device for quickly cutting off the power supply when leakage occurs. The leakage protection device can monitor the leakage current in the circuit in real time, and once it is detected that the leakage current exceeds the set value, the circuit will be cut off immediately.

[0058] The electric heating film 61 adopts a low-temperature heating film, and can be selected from at least one of graphene electric heating film, silicone electric heating film or carbon fiber heating film, preferably PET graphene electric heating film-polyester heating film. The electric heating film 61 meets the waterproof level ≥ IPX8, the thickness ≥ 0.25mm, preferably, the thickness is 0.25~0.6mm, and the power density is 80~200W / m 2 , preferably, the power density is 100W / m 2 or 150W / m 2 , electrothermal conversion efficiency ≥ 60%, heating uniformity ≤ ± 5 ℃, service life > 10 years.

[0059] In this embodiment, the height between the bottom of the heating drainage ditch and the upper limit of the permafrost is the limited height, and the method for determining the limited height is: The second daily water seepage is calculated based on the sum of the difference between the evaporation power and precipitation in the months with an average monthly temperature greater than 0°C and the parameters of the water-proof water accumulation structure. The second daily water seepage is the water seepage in the active layer of the permafrost area that does not enter the water-proof water accumulation structure. The calculation formula for the second daily water seepage is:

[0060] in is the daily second water volume, in m 3 / d, the daily second water inflow is the water in the second active layer, lThe distance between the heating drainage ditch and the toe of the roadbed slope; Based on the geological data of permafrost areas, the permeability coefficient of the second soil layer and the hydraulic gradient of the second soil layer are obtained so that water does not enter the active layer of the anti-water accumulation structure; The limited height is calculated using the second soil layer permeability coefficient, the second soil layer hydraulic gradient, and the second daily seepage volume. The calculation formula for the limited height is:

[0061] in To limit the height, the unit is mm, is the hydraulic gradient of the second soil layer, is the permeability coefficient of the second soil layer, the second soil layer hydraulic gradient and the second soil layer permeability coefficient are the soil layer parameters in the second active layer.

[0062] Example 3 This embodiment provides a method for preventing moisture accumulation in a roadbed on a mountain side or a slope side in a permafrost region, wherein the moisture accumulation structure of embodiment 2 is arranged on the mountain side or the slope side of the roadbed, and a heating drain ditch is arranged in the moisture accumulation structure. A permeable layer is arranged on the side of the moisture accumulation structure away from the roadbed, and is used to collect moisture in the permafrost region to the heating drain ditch; an electric heating film is arranged on the side of the moisture accumulation structure close to the roadbed, and is used to heat the heating drain ditch; Methods include monitoring temperature and relative humidity at the bottom of heated drains; When the temperature at the bottom of the heating drain ditch is ≥0°C and the relative humidity is ≥60%, the electric heating film is started to heat the bottom of the heating drain ditch to reach the heating temperature in Example 1; Maintain the constant temperature heating state of the heating drain ditch to evaporate the water until the relative humidity at the bottom of the heating drain ditch is less than 60%, then stop heating.

[0063] When the temperature in permafrost areas is above 0°C, the ice begins to melt and moisture-preventing structures collect water into heated drains.

[0064] When the humidity sensor shows that the relative humidity of the air in the soil pores is below 60%, it can generally be considered that there is no water accumulation in the soil. When the temperature is ≥0℃ and the relative humidity is ≥60%, there is water accumulation, and the electric heating film is started to heat and evaporate. T When the relative humidity is ≥60%, the heating state is maintained at a constant temperature. The heating temperature calculated generally T ≤25℃, according to ground temperature monitoring data, the highest ground temperature in the area in summer can reach 30℃, 5℃ is sufficient, so the heating film T max≤25℃ does not affect the growth of heated drainage ditch turf and the local ecosystem; when the relative humidity in the soil is <60%, stop heating.

[0065] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the heating temperature of a roadbed moisture accumulation protection structure, characterized in that: The following steps are involved: Obtain the sum of the differences between evaporation and precipitation in the months with a monthly average temperature greater than 0°C and the months with a monthly average temperature greater than 0°C throughout the year; Obtaining a first daily water seepage amount, where the first daily water seepage amount is the water seepage amount of water entering the moisture accumulating structure; According to the months with average monthly temperature greater than 0℃, the sum of the difference between evaporation power and precipitation, the first daily seepage volume, and the parameters of the moisture-proof accumulation structure, the surface evaporation loss of the moisture-proof accumulation structure is calculated. The calculation formula for the surface evaporation loss is: Where H is the surface evaporation loss, Q 1 is the first daily water seepage volume, B 1 is the average width of the heating drainage ditch in the structure to prevent moisture accumulation. To prevent moisture accumulation in the heating drainage ditch, the water collection length along the ditch length is is the number of months with a monthly average temperature greater than 0°C, c It is the sum of the difference between evaporation and precipitation in the months with an average monthly temperature greater than 0℃ throughout the year; The saturated vapor pressure on the surface of the heating drainage ditch in the anti-water accumulation structure is calculated based on the surface evaporation loss, and the heating temperature is calculated using the saturated vapor pressure. The calculation formula for the heating temperature is: In the formula T To prevent moisture accumulation in structures that heat the surface of the gutter, P m is the saturated vapor pressure, A, B, C is the Antoine constant.

2. A method for calculating the heating temperature of a roadbed water-proof structure according to claim 1, characterized in that: The implementation method to obtain the sum of the difference between evaporation power and precipitation is: Step S11, based on the meteorological data of the permafrost region, counting the months with an average monthly temperature greater than 0°C throughout the year; Step S12, obtaining monthly evaporation power and monthly precipitation data for months with a monthly average temperature greater than 0°C; Step S13, according to the monthly evaporation power and monthly precipitation data, the total difference between the evaporation power and the precipitation for the whole year is calculated. The calculation formula for the total difference between the evaporation power and the precipitation is: in PE i The evaporation power of the moon, P i Monthly precipitation.

3. A method for calculating the heating temperature of a roadbed water-proof structure according to claim 1, characterized in that: The method for obtaining the first daily seepage volume is: Step S21, based on the stratum and hydrological data of the permafrost area, obtaining the first soil layer permeability coefficient and the first soil layer hydraulic gradient of the active layer for water to enter the anti-water accumulation structure; Step S22, based on the permeability coefficient of the first soil layer and the hydraulic gradient of the first soil layer, the first daily water seepage amount of water entering the moisture-proof accumulation structure is calculated. The calculation formula of the first daily water seepage amount is: In the formula, is the permeability coefficient of the first soil layer, is the hydraulic gradient of the first soil layer, The cross-sectional area of ​​water.

4. A method for calculating the heating temperature of a roadbed water-proof moisture accumulation structure according to any one of claims 1 to 3, characterized in that: The calculation formula for saturated vapor pressure is: in P is the air pressure value; V m Indicates the daily average wind speed.

5. A method for preventing moisture accumulation on the roadbed on the mountain side or slope side in permafrost areas, characterized in that: A moisture-proof accumulation structure is arranged on the mountain side or slope side of the roadbed, wherein a heating drainage ditch is arranged in the moisture-proof accumulation structure, and a permeable layer is arranged on the side of the moisture-proof accumulation structure away from the roadbed, so as to collect moisture in the permafrost area to the heating drainage ditch; an electric heating film is arranged on the side of the moisture-proof accumulation structure close to the roadbed, so as to heat the heating drainage ditch; The method includes monitoring the temperature and relative humidity at the bottom of the heated drain; When the temperature at the bottom of the heating drainage ditch is ≥0°C and the relative humidity is ≥60%, the electric heating film is started for heating, so that the temperature at the bottom of the heating drainage ditch reaches the heating temperature calculated by the method for calculating the heating temperature of a roadbed moisture accumulation structure according to any one of claims 1 to 4; The heating drain ditch is maintained in a constant temperature heating state until the relative humidity at the bottom of the heating drain ditch is less than 60%, and then the heating is stopped.

6. A method for preventing moisture accumulation on a roadbed on a mountain side or a slope side in a permafrost region according to claim 5, characterized in that: The electric heating film meets the requirements of waterproof grade ≥ IPX8, thickness ≥ 0.25mm, power density 80~200W / m 2 , electrothermal conversion efficiency ≥ 60%, heating uniformity ≤ ± 5℃.

7. A moisture-proof accumulation structure for a roadbed on a mountain side or slope side in a permafrost region, characterized in that: A method for preventing moisture accumulation in a roadbed on a mountainside or slope side in a permafrost region as described in any one of claims 5-6, wherein the moisture accumulation structure comprises a permeable layer and a heating layer, the permeable layer is arranged on the side away from the roadbed, and the heating layer is arranged on the side close to the roadbed, turf is arranged on the permeable layer and the heating layer, and the heating layer comprises an electric heating film, an insulating layer and a waterproof layer arranged from top to bottom; the permeable layer and the heating layer enclose a semi-open heating drainage ditch, and a temperature sensor and a humidity sensor are arranged at the bottom of the heating drainage ditch corresponding to the heating layer.

8. The moisture-proof accumulation structure for roadbed on the mountain side or slope side in permafrost areas according to claim 7, characterized in that: The permeable layer includes a filter layer and a permeable membrane layer arranged in sequence, the filter layer includes a coarse sand layer, a medium sand layer, and a fine sand layer arranged in sequence, the coarse sand layer is arranged away from the roadbed; the thickness of the coarse sand layer is 8~30cm, the thickness of the medium sand layer is 10~20cm, the thickness of the fine sand layer is 10~20cm, the particle size of the gravel in the coarse sand layer is 5~20mm, the particle size of the gravel in the medium sand layer is 1~5mm, and the particle size of the gravel in the fine sand layer is 0.25~1mm.

9. The moisture-proof accumulation structure for roadbed on the mountain side or slope side in permafrost areas according to claim 7, characterized in that: The electric heating film is powered by a solar energy storage system.

10. A moisture-proof accumulation structure for roadbed on the mountain side or slope side in permafrost areas according to any one of claims 7 to 9, characterized in that: The height between the bottom of the heating drainage ditch and the upper limit of the permafrost is a limited height, and the method for determining the limited height is: The second daily water seepage is calculated based on the sum of the difference between the evaporation power and precipitation in the months with an average monthly temperature greater than 0°C and the parameters of the water-proof water accumulation structure. The second daily water seepage is the water seepage in the active layer of the permafrost area that does not enter the water-proof water accumulation structure. The calculation formula for the second daily water seepage is: in The second daily water inflow, l The distance between the heating drainage ditch and the toe of the roadbed slope; Based on the geological data of permafrost areas, the permeability coefficient of the second soil layer and the hydraulic gradient of the second soil layer are obtained so that water does not enter the active layer of the anti-water accumulation structure; The limited height is calculated using the second soil layer permeability coefficient, the second soil layer hydraulic gradient, and the second daily seepage volume. The calculation formula for the limited height is: in To limit the height, is the hydraulic gradient of the second soil layer.

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