An assembled cold-removal subgrade structure, construction method and design method

Abstract

The present application relates to the technical field of road subgrade construction, and particularly relates to an assembled cold-guiding subgrade structure, a construction method and a design method. The assembled cold-guiding subgrade structure can discharge the heat replaced by all permanent heat rods from the ground frost through the air ducts of the corresponding assembled subgrade modules, so that the permanent heat rods are arranged below the middle part of the subgrade in the transverse direction, the heat dissipation demand of the permanent heat rods can be met, uniform cooling can be realized in the range of the subgrade, the safety of the subgrade construction and operation is not affected by the setting of the assembled subgrade modules and filling sections, and the assembled subgrade modules are convenient to construct and have high efficiency. Before the construction of the assembled cold-guiding subgrade structure, the whole process energy balance of the construction and operation is considered, the time required for complete refreezing of the active layer is taken as the reference, the temporary heat rods are selectively arranged, the complete refreezing of the ground is realized before the construction, and the cold energy is reserved in advance to balance the thermal disturbance in the construction and operation period.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road subgrade construction, in particular to an assembled cold-guiding subgrade structure, a construction method and a design method. BACKGROUND

[0002] The permafrost area in China is 2.15 million square kilometers, accounting for about one fourth of the total land area, mainly distributed in the Qinghai-Tibet Plateau, the Greater and Lesser Xing'an Mountains in the northeast and the western plateau region. The permafrost in the Qinghai-Tibet Plateau, known as the "Roof of the World" and the "Third Pole", is high-altitude permafrost. The extremely harsh climate and geographical environment are the root cause of the impact on engineering construction, so the road engineering in the Qinghai-Tibet Plateau region presents the characteristics of obvious regional short board and backward traffic network. In addition, in recent years, affected by the extreme high temperature and rainfall events in the Qinghai-Tibet Plateau, the degradation of permafrost and the melting of glaciers in the Qinghai-Tibet Plateau have significantly increased, and the derived geological disasters such as thermal melting collapse, ice lake outburst and thawing mud flow have intensified, which poses greater challenges to the high-quality and safe operation of highways. In the face of the technical problems of highway design and construction in the Qinghai-Tibet Plateau region, the design principles for protecting permafrost are proposed for the construction of highways in permafrost regions. The thermal rod subgrade, as an "active refrigeration measure", has been widely used in permafrost highways. The relevant engineering monitoring data shows that the refrigeration effect of the thermal rod is very obvious, the ground temperature near the thermal rod is lower than the natural hole ground temperature, and it can remain stable for a long time, which has a significant effect on improving the stability of the subgrade.

[0003] In the past, the heat rod is generally laid on both sides of the roadbed, located in the middle of the road shoulder or slope, and arranged at equal intervals along the longitudinal direction of the roadbed. However, as a point-like cooling measure, the heat rod has a limited cooling range. In addition, the arrangement of the heat rod in the past only considers the construction period. When the cold energy stored in the foundation cannot balance the heat released during the construction period, the heat rod still needs to balance the heat released during the construction period in the first few years of operation, thereby causing some unnecessary initial diseases. Therefore, it is necessary to adjust the heat rod layout method and layout range from the perspective of overall energy balance to reduce the frozen soil temperature of the roadbed and a certain depth range. The Chinese patent with publication number CN106120506B discloses a heat rod roadbed parameter design method in permafrost regions based on energy balance principle. The structure parameters and layout spacing of the heat rod are calculated based on the construction period, and the operation period is not considered. That is, the heat rod design in the prior art does not consider the complete freezing period of the foundation, but only calculates the number of heat rods according to the freezing period required during the construction period. This will result in some heat not being released from the foundation, remaining in the operation period, i.e., the construction period and the operation period are not considered together, thereby adversely affecting highway operation. The Chinese patent with publication number CN116657586B discloses a targeted focusing heat rod array applied to a road-bridge transition section. The heat rod array is mentioned, but only for the road-bridge transition section. The heat rods are arranged in a fan array near the abutment and pile foundation on one side of the roadbed. Although this can achieve the effect of cooling the foundation, the energy balance is not considered.

[0004] The heat rod arrays in the above arrangement are all on both sides of the roadbed, so that the heat rods can be directly exposed to facilitate heat dissipation of the heat rods. When the required cold energy in the foundation is large, only relying on the heat rod array arranged on both sides of the roadbed cannot meet the corresponding cooling demand of the foundation. Since it is difficult to dissipate heat from the heat rods in the middle of the roadbed and the construction of the roadbed is affected, the prior art cannot arrange the heat rod array in the middle of the roadbed. SUMMARY

[0005] The purpose of the present application is to overcome the problem in the prior art that when the heat rod array is used to cool the foundation under the roadbed, the heat rod array is arranged on both sides of the roadbed, and only relying on the heat rod array arranged on both sides of the roadbed cannot meet the corresponding cooling demand of the foundation. In order to provide sufficient heat dissipation channels for the heat rods, reduce the impact on the roadbed body, and realize rapid construction, a kind of assembled cold-guiding roadbed structure, construction method and design method are provided.

[0006] In a first aspect, the present application provides an assembled cold-guiding roadbed structure, comprising:

[0007] The bottom structure comprises a plurality of assembled roadbed modules and a plurality of filling sections, the assembled roadbed modules are arranged along the roadbed transversely, the assembled roadbed modules are distributed along the roadbed longitudinally, the bottom of the assembled roadbed module is used for embedding into the foundation, and the filling section is filled between two adjacent assembled roadbed modules along the roadbed longitudinally; a plurality of mounting holes are arranged at the bottom of the assembled roadbed module along the length direction of the assembled roadbed module, a ventilation channel is arranged in the assembled roadbed module along the length direction of the assembled roadbed module, the ventilation channel is communicated with all the mounting holes of the assembled roadbed module, and the ventilation channel comprises an air inlet and an air outlet.

[0008] The upper structure is arranged above the bottom structure.

[0009] The heat rod array comprises a plurality of permanent heat rods, the permanent heat rods are arranged in the corresponding mounting holes, the condensation section at the upper part of the permanent heat rod extends into the corresponding ventilation channel, the evaporation section at the lower part of the permanent heat rod is used for extending below the permafrost upper limit in the foundation, and all the permanent heat rods are arranged in the roadbed by the assembled roadbed module.

[0010] The assembled cold-conducting roadbed structure has the advantages that the filling section is filled between two adjacent assembled roadbed modules along the roadbed longitudinally, so that the bottom structure is complete, and the smooth arrangement of the upper structure is ensured; the filling section can adapt to the longitudinal deformation of the roadbed, so that the possibility of transverse displacement of the assembled roadbed module is reduced, and the integrity of the bottom structure in the longitudinal deformation of the roadbed is ensured; the bottom of the assembled roadbed module is used for embedding into the foundation, so that the transverse and longitudinal positions of the assembled roadbed module are further ensured, and the stability of the structure and the safety of the later operation are ensured; the permanent heat rod is arranged in the corresponding mounting hole at the bottom of the assembled roadbed module, the condensation section at the upper part of the permanent heat rod extends into the corresponding ventilation channel, the evaporation section at the lower part of the permanent heat rod is used for extending below the permafrost upper limit in the foundation, the ventilation channel is communicated with all the mounting holes of the assembled roadbed module, the ventilation channel comprises an air inlet and an air outlet, the air inlet and the air outlet can be communicated with the outside of the roadbed, the heat of all the permanent heat rods replaced from the permafrost in the foundation can be discharged through the ventilation channel of the corresponding assembled roadbed module, so that the permanent heat rod can be arranged below the middle part of the roadbed transversely, the heat dissipation of the permanent heat rod can be met, all the permanent heat rods can be arranged in the roadbed by the assembled roadbed module, a larger number of permanent heat rods can be arranged, more cold energy can be provided for the foundation, uniform cooling can be realized in the range of the roadbed, the arrangement of the assembled roadbed module does not affect the safety of the roadbed construction and operation, the assembled roadbed module is convenient and efficient in construction.

[0011] Preferably, the cross section of the assembled subgrade module is square, rectangular, trapezoidal or the like.

[0012] Preferably, the cross section of the ventilation channel is rectangular, circular, elliptical or the like.

[0013] Preferably, the assembled subgrade module comprises a bottom plate and an upper cover part, the mounting holes are arranged on the bottom plate in the transverse direction of the subgrade, the mounting slots are arranged on the two sides of the bottom plate in the longitudinal direction of the subgrade, the mounting slots are arranged in the transverse direction of the subgrade, and the mounting slots on the two sides are located on the two sides of the mounting holes, the upper cover part comprises a top plate and two side plates arranged in the longitudinal direction of the subgrade, the side plates can be inserted into the corresponding mounting slots, and the ventilation channel is formed between the bottom plate, the top plate and the two side plates; the assembled subgrade module is divided into a bottom plate and an upper cover part, the bottom plate and the upper cover part are sequentially constructed after the permanent heat rod is constructed, the mounting holes on the bottom plate are convenient for aligning the permanent heat rod, and the side plates of the upper cover part are convenient for aligning the mounting slots on the bottom plate, so that the installation process is simpler, and the function of the assembled subgrade module is not affected.

[0014] Alternatively, the assembled subgrade module comprises two groove-shaped members, the openings of the two groove-shaped members are oppositely arranged, the openings of the groove-shaped members are arranged in the longitudinal direction of the subgrade, the bottoms of the two groove-shaped members are provided with a plurality of opposite semicircular notches, and the opposite two semicircular notches are combined to form the mounting hole. The assembled subgrade module adopts two groove-shaped members, the semicircular notches of one groove-shaped member are aligned with the constructed permanent heat rod, and then the other groove-shaped member is installed based on the one groove-shaped member, so that the installation is more convenient, and the function of the assembled subgrade module is not affected.

[0015] Preferably, the top of the ventilation channel is provided with a heat insulation plate, so as to reduce the direct heat transfer capacity of the upper structure to the foundation.

[0016] Preferably, at least two assembled subgrade modules are continuously arranged in the transverse direction of the subgrade, and the two adjacent assembled subgrade modules in the transverse direction of the subgrade are connected to each other in a grouting mode.

[0017] When the transverse size of the subgrade is large, at least two assembled subgrade modules are continuously arranged in the transverse direction of the subgrade, which is convenient for transportation and installation, and the two adjacent assembled subgrade modules in the transverse direction of the subgrade are connected to each other in a grouting mode, so that the sealing of the two adjacent assembled subgrade modules in the transverse direction of the subgrade is realized, the ventilation channel is continuous, and the heat dissipation effect is better.

[0018] Preferably, the air inlet and the air outlet are arranged on the two end faces in the length direction of the assembled subgrade module; convection is formed, and the heat dissipation effect is better.

[0019] And / or, the upper structure is provided with a cushion layer, a bidirectional geogrid and a pavement structure layer in sequence from bottom to top, and the cushion layer and the pavement structure layer are provided with slopes on both sides in the lateral direction. The lateral distance between the permanent heat pipes installed on both sides of the roadbed and the slope toe of the corresponding slope is not less than 0.5m.

[0020] And / or, the prefabricated roadbed module adopts one or a combination of reinforced concrete, construction solid waste, industrial solid waste and foamed concrete;

[0021] And / or, the filling section adopts one or more of the following: soil, crushed stone and gravel; it has a better effect on adapting to subgrade deformation.

[0022] In a second aspect, the present invention provides a construction method for a prefabricated cooling-conducting roadbed structure, used for constructing the prefabricated cooling-conducting roadbed structure, comprising the following steps:

[0023] S01. Level the site and mark the location of all heat pipes on the construction site; t is the time required for the active layer to fully refreeze. f The refreezing time t is longer than the construction period requirement. d At that time, the heating system includes several permanent heating elements and several temporary heating elements; the time t required for the active layer to fully refreeze. f The refreezing time t is less than or equal to the construction period requirement. d At that time, the heat pipes included several permanent heat pipes;

[0024] S02. Install all heat pipes in the indicated positions, so that the evaporation end of the heat pipe is inserted below the upper limit of the frozen soil in the natural foundation.

[0025] S03, the time t required for the active layer to fully refreeze. f The refreezing time t is longer than the construction period requirement. d At t d The temporary heating elements installed during construction were then removed, and their holes were backfilled. The prefabricated roadbed modules were then installed. The time required for the active layer to fully refreeze is t. f The refreezing time t is less than or equal to the construction period requirement. d At t f The prefabricated roadbed modules were then installed.

[0026] S04, Construction filling section;

[0027] S05. Construction of the superstructure.

[0028] The prefabricated cooling roadbed construction method of the present invention reduces the time t required for the active layer to fully refreeze. f The required refreezing time t during the construction period dThe comparison allows for the selection of temporary heat pipes to dissipate heat from the foundation, accelerating the refreezing of the foundation and ensuring stable construction of both the lower and upper structures during the construction period. Furthermore, it ensures that the time required for the active layer to fully refreeze is within a certain timeframe. f Related to the operation period, this method considers the energy balance of the entire process during both the construction and operation periods; and the prefabricated roadbed modules have a high degree of prefabrication, good construction quality, and high construction efficiency; temporary heat pipes can be reused, greatly reducing project costs.

[0029] In a third aspect, the present invention provides a design method for the construction of a prefabricated cooling-conducting roadbed structure, which guides the construction method of the prefabricated cooling-conducting roadbed structure, and includes the following steps:

[0030] S1: Calculate the annual heat transfer Q2 of the permanent heat pipes and the spacing s of the permanent heat pipes under the design conditions using the energy balance method. s And calculate the amount of cold energy required, Q1, to completely refreeze the active layer of the natural foundation;

[0031] S2: Based on the annual heat transfer Q2 of the permanent heat pipes and the arrangement spacing s of the permanent heat pipes. s The calculation of the cold energy requirement Q1 for the complete refreezing of the active layer of the natural foundation, and the time t required for the active layer to fully refreeze. f The time t required for the active layer to fully refreeze f The calculation formula is:

[0032]

[0033] S3: Determine the time t required for the active layer to fully refreeze. f Is the refreezing time t greater than the required construction period? d If so, determine the number m of temporary heating elements (m) to be added to the roadbed cross-section during the construction period and the center-to-center distance s between adjacent temporary heating elements, and then base this on the permanent heating element spacing s. s The number of temporary heating elements (m) on the roadbed cross-section and the center-to-center distance (s) between adjacent temporary heating elements guide the construction of permanent and temporary heating elements; otherwise, the construction should be based on the spacing (s) of the permanent heating elements. s Provide guidance on the construction of permanent heating elements.

[0034] This invention provides a design method for the construction of the prefabricated cooling subgrade structure, which can calculate the time t required for the active layer to fully refreeze. f This allows for the adjustment of the freezing time t required by the construction schedule. d Comparisons can provide guidance on whether temporary heat pipes should be installed during the construction of prefabricated cooling roadbed structures, which will help ensure the smooth construction of prefabricated cooling roadbed structures.

[0035] Preferably, in step S1, the formula for calculating the cold energy requirement Q1 for completely refreezing the active layer of the natural foundation is:

[0036]

[0037] wherein: n is the number of divisions of the active layer, n≥1; i is the index; H i is the thickness of the i-th layer; W is the width between the slope feet of the roadbed transverse sides; p di is the dry density of the i-th layer; C i is the specific heat capacity of the i-th layer; T avgi is the average ground temperature of the i-th layer; T pci is the phase change temperature of the i-th layer of soil; ω i is the water content of the i-th layer; ω iu is the immobile water content of the i-th layer; L is the latent heat of crystallization or melting of ice of water.

[0038] The cold energy requirement Q1 is calculated by the calculation formula of the cold energy requirement Q1 of the complete refreezing of the natural ground active layer, which has high calculation accuracy and small calculation amount.

[0039] Preferably, in step S3, the effective radius s s ' of the temporary heat rod during construction is calculated first. s The calculation formula of the effective radius s s ' of the temporary heat rod during construction is:

[0040]

[0041] wherein: Δt is the working time of the temporary heat rod in a year; t is the time variable; T s is the annual average ground temperature; T a is the annual average air temperature; d0 is the outer diameter of the temporary heat rod; R a is the thermal resistance of the temporary heat rod; λ f is the thermal conductivity of the fin of the temporary heat rod; L e is the length of the evaporation section of the temporary heat rod;

[0042] Then, the number m of the temporary heat rods on the roadbed cross section is calculated according to the effective radius s s ' of the temporary heat rod, and the calculation formula of the number m of the temporary heat rods on the roadbed cross section is:

[0043]

[0044] wherein: W is the width between the slope feet of the roadbed transverse sides;

[0045] And the center distance s between adjacent temporary heat rods is calculated according to the effective radius s s ' of the temporary heat rod and the arrangement mode of the added temporary heat rod.

[0046] When the arrangement mode of the added temporary heat rod is a square, s=s s / 1.128; When the arrangement of the newly added temporary heat pipes is an equilateral triangle, s = s s ' / 1.05.

[0047] The above calculation method can quickly and accurately calculate the number of temporary heating rods (m) and the center-to-center distance (s) of adjacent temporary heating rods that need to be added to the roadbed cross section during the construction period, which is convenient for guiding the layout of temporary heating rods.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. This invention provides a prefabricated cooling roadbed structure. A permanent heat pipe is installed in the corresponding mounting hole at the bottom of the prefabricated roadbed module. The condensation section of the permanent heat pipe extends into the ventilation duct of the corresponding prefabricated roadbed module, and the evaporation section of the permanent heat pipe extends below the upper limit of the frozen soil in the foundation. The ventilation duct connects all the mounting holes of the prefabricated roadbed module and includes an air inlet and an air outlet. The air inlet and outlet can connect to the outside of the roadbed, meaning that all the heat dissipated by the permanent heat pipe from the frozen soil in the foundation can be transferred through the ventilation duct. The heat is discharged through the ventilation ducts of the corresponding prefabricated roadbed modules, which allows permanent heat pipes to be placed in the lower middle of the transverse side of the roadbed. This also satisfies the heat dissipation of the permanent heat pipes. Furthermore, the prefabricated roadbed modules can be used to array all the permanent heat pipes within the roadbed, allowing for the installation of a larger number of permanent heat pipes, which is beneficial for providing more cooling energy to the foundation. It also enables uniform cooling within the roadbed area. Moreover, the prefabricated roadbed modules, in conjunction with the filling section, do not affect the safety of roadbed construction and operation. In addition, the prefabricated roadbed modules are convenient and efficient to construct.

[0050] 2. This invention provides a construction method for a prefabricated cooling roadbed structure, which reduces the time t required for the active layer to fully refreeze. f The required refreezing time t during the construction period d The comparison allows for the selection of temporary heat pipes to dissipate heat from the foundation, which can accelerate the refreezing rate of the foundation and meet the requirements for stable construction of the bottom and upper structures during the construction period; moreover, the prefabricated roadbed modules have a high degree of assembly, good construction quality, and high construction efficiency; the temporary heat pipes can be reused, which greatly reduces the project cost.

[0051] 3. This invention provides a design method for the construction of prefabricated cooling subgrade structures, which calculates the time t required for the active layer to fully refreeze. f This allows for the adjustment of the freezing time t required by the construction schedule. d Comparisons can provide guidance on whether temporary heat pipes should be installed during the construction of prefabricated cooling roadbed structures, which will help ensure the smooth construction of prefabricated cooling roadbed structures. Attached Figure Description

[0052] Figure 1Schematic diagram of cross section for assembled cold-lead roadbed structure;

[0053] Figure 2 Schematic diagram of structure for assembled roadbed module (bottom side is bottom);

[0054] Figure 3 Schematic diagram of first structure arrangement for assembled roadbed module;

[0055] Figure 4 Schematic diagram of second structure cross section for assembled roadbed module;

[0056] Figure 5 Schematic diagram of structure for channel member;

[0057] Figure 6 Schematic diagram of plane for permanent heat rod arranged in square array;

[0058] Figure 7 Schematic diagram of parameter for temporary heat rod arranged in square array;

[0059] Figure 8 Schematic diagram of plane for permanent heat rod arranged in equilateral triangle array;

[0060] Figure 9 Schematic diagram of parameter for temporary heat rod arranged in equilateral triangle array.

[0061] Markings in the figure: 1, assembled roadbed module; 101, mounting hole; 1011, semicircular notch; 102, ventilation channel; 11, bottom plate; 111, mounting groove; 12, top plate; 13, side plate; 14, channel member; 15, heat insulation plate; 21, permanent heat rod; 22, temporary heat rod; 3, foundation; 4, cushion layer; 5, bidirectional geogrid; 6, pavement structure layer; 7, slope; 8, filling section. DETAILED DESCRIPTION

[0062] The application will be further described below in connection with specific embodiments. However, it should not be understood that the above-mentioned subject matter of the application is limited to the following embodiments only, and any technology realized based on the content of the application falls within the scope of the application.

[0063] In the description of specific embodiments of the present application, the terms of orientation or positional relationship such as "upper", "lower", "left", "right", "center", "inner", "outer" and the like are expressed based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product / device / apparatus of the present application is usually used, unless otherwise specified. These terms of orientation or positional relationship are only for the convenience of describing the present application or simplifying the description in specific embodiments, for the purpose of facilitating the understanding of the scheme by the skilled person, and therefore cannot be understood as indicating or implying that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship, and therefore cannot be understood as limiting the present application.

[0064] In addition, the terms "horizontal", "vertical", "overhanging", "parallel" and the like do not mean that the corresponding device / component / element must be absolutely horizontal or vertical or overhanging or parallel, but can be slightly inclined or deviated. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to mean that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "overhanging", "parallel" and the like, and can have an error / deviation of ±10% with respect to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. 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 application.

[0065] In addition, the terms "first", "second", "third" and the like in the description of the present application are only used to distinguish the same or similar components for description, and should not be understood as emphasizing or implying the relative importance of the specific components.

[0066] In addition, in the description of the embodiments of the present application, "several", "a plurality of", "several" represent at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. in any case, and even more than 9.

[0067] In addition, in the description of the technical scheme of the present application, unless otherwise specified / limited / limited, the terms "arrangement", "installation", "connection", "connection", "provided with", "laid", "arrangement" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, such as welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication between two elements.

[0068] Example 1

[0069] As shown in Figure 1 , an assembled cold-removal subgrade structure includes a bottom structure, an upper structure, and a heat rod array.

[0070] As shown in Figure 6 and Figure 8 , the bottom structure includes a plurality of assembled subgrade modules 1 and a plurality of filling sections 8, and the upper structure is arranged above the bottom structure, i.e., the upper structure is arranged on the assembled subgrade modules 1 and the filling sections 8.

[0071] The assembled subgrade module 1 is made of a combination of one or more of reinforced concrete, construction solid waste, industrial solid waste, and foamed concrete.

[0072] In this embodiment, the upper structure is sequentially provided with a cushion layer 4, a bidirectional geogrid 5, and a pavement structure layer 6 from bottom to top, and the lateral sides of the cushion layer 4 and the pavement structure layer 6 are provided with side slopes 7, i.e., the cushion layer 4 is arranged on the assembled subgrade modules 1 and the filling sections 8.

[0073] As shown in Figure 1 and Figure 6 , the assembled subgrade modules 1 are arranged along the lateral direction of the subgrade, i.e., the left-right direction of Figure 1 and Figure 6 . The assembled subgrade modules 1 are distributed in the longitudinal direction of the subgrade, i.e., the up-down direction of Figure 6 . The bottom of the assembled subgrade module 1 is used to be embedded in the foundation 3 to ensure the lateral and longitudinal positions of the assembled subgrade module 1, thereby ensuring the stability of the structure and the safety of the later operation. The filling section 8 is filled between two adjacent assembled subgrade modules 1 in the longitudinal direction of the subgrade; the filling section is made of a combination of one or more of fill, gravel, and sand, which is better adapted to the deformation of the subgrade. The bottom structure is filled between two adjacent assembled subgrade modules 1 in the longitudinal direction of the subgrade by the filling section 8, so that the bottom structure is complete and the upper structure is smoothly arranged; the filling section 8 can adapt to the longitudinal deformation of the subgrade, thereby reducing the possibility of misplacement of the assembled subgrade module 1 in the lateral direction and ensuring the integrity of the bottom structure in the longitudinal deformation of the subgrade.

[0074] As shown in Figures 2-4 , a plurality of mounting holes 101 are arranged at the bottom of the assembled subgrade module 1 in the length direction of the assembled subgrade module 1, and the mounting holes 101 are used to arrange permanent heat rods 21. The mounting holes are arranged in a pattern matching the arrangement of the permanent heat rods. A ventilation channel 102 is arranged inside the assembled subgrade module 1 in the length direction of the assembled subgrade module 1, the ventilation channel 102 communicates with all the mounting holes 101 of the assembled subgrade module 1, the ventilation channel 102 includes an air inlet and an air outlet, and the air inlet and the air outlet can communicate with the outside of the subgrade;

[0075] The cross section of the assembled roadbed module 1 is square, rectangular, trapezoidal, or the like.

[0076] The cross section of the ventilation channel 102 is rectangular, circular, elliptical, or the like.

[0077] When the cross section of the assembled roadbed module 1 is square and the cross section of the ventilation channel 102 is rectangular, as shown in Figure 2 .

[0078] In some embodiments, the top of the ventilation channel 102 is provided with a heat insulation plate, which reduces the ability of the superstructure to directly transfer heat to the foundation and reduces the influence of heat radiation of the superstructure on the heat dissipation of the foundation. The heat insulation plate material can be glass fiber, asbestos, rock wool, silicate, aerogel felt, or vacuum plate, etc.

[0079] In one embodiment, as shown in Figure 3 , the assembled roadbed module 1 includes a bottom plate 11 and an upper cover part, the bottom plate 11 is provided with the mounting hole 101 along the transverse direction of the roadbed, the bottom plate 11 is provided with a mounting groove 111 along the longitudinal direction of the roadbed, the mounting groove 111 is arranged along the transverse direction of the roadbed, and the mounting grooves 111 on both sides are located on both sides of the mounting hole 101, the upper cover part includes a top plate 12 and two side plates 13 arranged along the longitudinal direction of the roadbed, the side plates 13 can be fitted into the corresponding side of the mounting groove 111, and the bottom plate 11, the top plate 12, and the two side plates 13 form the ventilation channel 102; The assembled roadbed module 1 is divided into a bottom plate 11 and an upper cover part, after the permanent heat rod 21 is constructed, the bottom plate 11 and the upper cover part are sequentially constructed, the mounting hole on the bottom plate 11 is convenient for aligning the installation of the permanent heat rod 21, and the side plate of the upper cover part is convenient for aligning the mounting groove 111 on the bottom plate, so that the installation process is simpler, and the function of the assembled roadbed module 1 is not affected. Further, the heat insulation plate 15 can be located on the lower surface of the top plate, inside, or on the upper surface of the top plate. In this embodiment, the heat insulation plate 15 is embedded in the top plate 12 and the two side plates 13 when the assembled roadbed module is prefabricated.

[0080] In another embodiment, as shown in Figure 4 and Figure 5As shown, the prefabricated roadbed module 1 comprises two groove-shaped members 14, the openings of the two groove-shaped members 14 are oppositely arranged, the openings of the groove-shaped members 14 are arranged along the longitudinal direction of the roadbed, and the bottoms of the two groove-shaped members 14 are provided with a plurality of opposite semicircular notches 1011, and the opposite two semicircular notches 1011 are combined to form the mounting hole 101. The prefabricated roadbed module 1 uses two groove-shaped members 14, and the semicircular notches 1011 of one groove-shaped member 14 are aligned with the constructed permanent heat rod 21, and then the other groove-shaped member 14 is installed based on the groove-shaped member 14, which is more convenient to install and does not affect the function of the prefabricated roadbed module 1. Further, the heat insulation plate 15 is embedded in the groove-shaped member 14 when the prefabricated roadbed module is prefabricated.

[0081] As shown in Figure 1 and Figure 6 When the transverse width of the roadbed is relatively narrow, one prefabricated roadbed module 1 can be arranged across the roadbed, as shown in Figure 1 The left and right end faces of the prefabricated roadbed module 1 are outside the left and right sides of the roadbed, which is further effective and beneficial to the heat dissipation of the heat rod to the foundation. That is, the air inlet and air outlet are arranged at the lengthwise end faces of the prefabricated roadbed module 1; convection is formed, and the heat dissipation effect is better.

[0082] When the transverse size of the roadbed is relatively large, at least two prefabricated roadbed modules 1 are arranged continuously in the transverse direction of the roadbed, which is convenient for transportation and installation, and the two prefabricated roadbed modules 1 are connected to each other by grouting, which can realize the sealing of the two prefabricated roadbed modules 1, so that the ventilation channel 102 is continuous, and the heat dissipation effect is better.

[0083] The heat rod array comprises a plurality of permanent heat rods 21, the permanent heat rods 21 are arranged in the corresponding mounting holes 101, the condensation section of the upper part of the permanent heat rod 21 extends into the corresponding ventilation channel 102, and the evaporation section of the lower part of the permanent heat rod 21 is used to extend into the permafrost below the upper limit of the foundation 3. All the permanent heat rods 21 are arranged in the roadbed by the prefabricated roadbed module 1.

[0084] As shown in Figure 1 The transverse distance between the permanent heat rod 21 installed on the left and right sides of the roadbed and the toe of the corresponding side slope 7 is not less than 0.5m.

[0085] The prefabricated cooling subgrade structure described in this embodiment allows all the heat dissipated from the frozen soil within the foundation 3 by the permanent heat pipes 21 to be discharged through the ventilation ducts 102 of the corresponding prefabricated subgrade modules 1. This enables the permanent heat pipes 21 to be positioned below the transverse center of the subgrade, thus satisfying the heat dissipation requirements of the permanent heat pipes 21. Furthermore, the prefabricated subgrade modules 1 can be used to array all the permanent heat pipes 21 within the subgrade, allowing for a larger number of permanent heat pipes 21 to provide more cooling energy to the foundation. The uniform distribution within the subgrade enables uniform cooling within the subgrade area. Moreover, the installation of the prefabricated subgrade modules 1 does not affect the safety of subgrade construction and operation, and the prefabricated subgrade modules 1 are convenient and efficient to construct.

[0086] Example 2

[0087] A construction method for a prefabricated cooling-conducting roadbed structure, used for constructing the prefabricated cooling-conducting roadbed structure described in Example 1, includes the following steps:

[0088] S01. Level the site and mark the location of all heat pipes on the construction site; t is the time required for the active layer to fully refreeze. f The refreezing time t is longer than the construction period requirement. d At that time, the heat pipes include several permanent heat pipes 21 and several temporary heat pipes 22; the time t required for the active layer to completely refreeze. f The refreezing time t is less than or equal to the construction period requirement. d At that time, the heat pipe includes several permanent heat pipes 21;

[0089] S02. Install all heat pipes in the indicated positions, so that the evaporation end of the heat pipe is inserted below the upper limit of the frozen soil in the natural foundation.

[0090] S03, the time t required for the active layer to fully refreeze. f The refreezing time t is longer than the construction period requirement. d At t d The temporary heating element 22, which was added during the construction period, was then removed and the heating element holes of the temporary heating element 22 were backfilled. Then, the prefabricated roadbed module 1 was installed. The time t required for the active layer to fully refreeze... f The refreezing time t is less than or equal to the construction period requirement. d At t f Install prefabricated roadbed module 1 later;

[0091] The prefabricated roadbed modules are manufactured according to their size, shape, permanent heating element arrangement, and quantity. When at least two prefabricated roadbed modules 1 are used in the transverse direction of the roadbed, the two adjacent prefabricated roadbed modules 1 are connected by grouting or other methods.

[0092] S04, construction of the filling section; filled between the same two assembled roadbed modules 1 in the longitudinal direction of the roadbed, such as gravel and sand.

[0093] S05, construction of the superstructure.

[0094] In step S05, the construction of the superstructure includes the sequential construction of the cushion layer 4, the laying of the bidirectional geogrid 5, and the construction of the pavement structure layer 6. When the cushion layer 4 and the pavement structure layer 6 are constructed, the two side slopes 7 are simultaneously constructed.

[0095] The hot rod design of the prior art does not consider the complete refreezing period of the foundation, but only calculates the number of hot rods according to the required refreezing period during construction, which will result in part of the heat of the foundation not being released and being preserved during the operation period, i.e., the construction period and the operation period are not considered in combination, thereby adversely affecting the highway operation. Therefore, the energy balance of the entire process of foundation construction and operation needs to be realized in combination with the two stages. The assembled cold-guided roadbed structure construction method described in the embodiment can select temporary hot rods 22 to dissipate heat from the foundation by comparing the time t f required for the complete refreezing of the active layer with the required refreezing time t d during the construction period, so that the temporary hot rods can accelerate the refreezing of the foundation, meet the stable construction of the bottom structure and the superstructure during the construction period, and the time t f required for the complete refreezing of the active layer is related to the operation period, i.e., the method considers the complete refreezing period of the foundation and the cold energy required for the complete refreezing of the foundation, so that the method simultaneously considers the entire process energy balance of the construction period and the operation period, achieves the energy balance of the entire process of construction and operation, and the assembled roadbed module 1 has high assembly degree, good construction quality, and high construction efficiency, i.e., on the basis of the hot rod control of soil melting, the intelligent construction technology of the roadbed is combined to realize high-quality and rapid construction of the roadbed; the temporary hot rods can be reused, which greatly reduces the engineering cost.

[0096] Embodiment 3

[0097] The application provides a design method for the construction of an assembled cold-guided roadbed structure, which is used to guide the construction method of the assembled cold-guided roadbed structure and includes the following steps:

[0098] S1: calculating the annual heat transfer amount Q2 of the permanent hot rod 21 and the arrangement interval s s of the permanent hot rod 21 under the design condition according to the energy balance method; and calculating the cold energy requirement Q1 for the complete refreezing of the active layer of the natural foundation 3;

[0099] In step S1, the annual heat transfer amount Q2 of the permanent hot rod 21 is related to the model of the permanent hot rod 21 and can be calculated according to relevant specifications. The arrangement interval s s of the permanent hot rod 21 can be referred to relevant specifications.

[0100] In step S1, the formula for calculating the cold energy requirement Q1 for completely refreezing the active layer of the natural foundation 3 is as follows:

[0101]

[0102] In the formula: n is the number of parts to divide the activity layer, n≥1; i is the index; H i ρ is the thickness of the i-th layer; W is the width between the toes of the slopes on both sides of the roadbed; di C is the dry density of the i-th layer; i T is the specific heat capacity of the i-th layer; avgi T represents the average geothermal temperature of the i-th layer. pci ω is the phase transition temperature of the i-th soil layer; i ω represents the water content of the i-th layer; iu Let L be the undisturbed water content of the i-th layer; L be the latent heat of water crystallization or ice melting. Preferably, the active layer is divided into n layers through geological stratification.

[0103] The cold energy demand Q1 is calculated using the formula for calculating the cold energy demand Q1 when the active layer of the natural foundation 3 is completely refreezed. The calculation is accurate and requires little computation.

[0104] S2: Based on the annual heat transfer Q2 of the permanent heat pipe 21 and the arrangement spacing s of the permanent heat pipe 21 s Calculate the cold energy requirement Q1 for the complete refreezing of the active layer of the natural foundation 3, and the time t required for the active layer to fully refreeze. f The time t required for the active layer to fully refreeze f The calculation formula is:

[0105]

[0106] S3: Determine the time t required for the active layer to fully refreeze. f Is the refreezing time t greater than the required construction period? d If so, determine the number m of temporary heating rods 22 that need to be added to the roadbed cross section during the construction period and the center-to-center distance s between adjacent temporary heating rods 22, and based on the distance s of the permanent heating rods 21. s The number m of temporary heating rods 22 on the roadbed cross section and the center-to-center distance s of adjacent temporary heating rods 22 guide the construction of permanent heating rods 21 and temporary heating rods 22; otherwise, the construction of permanent heating rods 21 and temporary heating rods 22 is guided by the spacing s of the permanent heating rods 21. s The construction of permanent heating element 21 is guided. The required refreezing time t during the construction period is specified. d It is related to geographical location and geological strata.

[0107] In step S3, the effective radius s of the temporary heating element 22 during the construction period is first calculated. s ', Temporary heating element with an effective radius of 22 s during construction period s The formula for calculating ' is:

[0108]

[0109] In the formula: Δt is the working time of temporary heating rod 22 in one year; t is the time variable; T s The average annual ground temperature; T a The annual average temperature; d0 is the outer diameter of the temporary heat pipe 22; R a For the temporary heat pipe 22 thermal resistance; λ f L is the thermal conductivity of the fins of temporary heat pipe 22. e The length of the evaporation section of the temporary heat pipe 22;

[0110] Then, based on the effective radius s of the temporary heating rod 22 s The formula for calculating the number m of temporary heating elements 22 on the roadbed cross section is as follows:

[0111]

[0112] In the formula: W is the width between the toes of the two sides of the roadbed in the transverse direction;

[0113] And based on the effective radius s of the temporary heating rod 22 s 'Calculate the center-to-center distance s of adjacent temporary heat pipes 22 based on the arrangement of the newly added temporary heat pipes 22;

[0114] When the newly added temporary heating rod 22 is arranged in a square shape, such as Figure 7 As shown, s = S s ' / 1.128; When the arrangement of the newly added temporary heat pipe 22 is an equilateral triangle, such as Figure 9 As shown, s = S s ' / 1.05.

[0115] The above calculation method can quickly and accurately calculate the number m of temporary heating rods 22 that need to be added to the roadbed cross section during the construction period and the center-to-center distance s of adjacent temporary heating rods 22, which is convenient for guiding the layout of temporary heating rods 22.

[0116] This embodiment provides a design method for the construction of the prefabricated cooling subgrade structure, which can calculate the time t required for the active layer to fully refreeze. f This allows for the adjustment of the freezing time t required by the construction schedule. d The comparison will provide guidance on whether to install temporary heat pipes 22 when constructing prefabricated cooling roadbed structures, which will help ensure the smooth construction of prefabricated cooling roadbed structures.

[0117] In this invention, before the construction of the prefabricated cooling roadbed structure, the energy balance of the entire construction and operation process is considered, taking the time t required for the active layer to fully refreeze as an example. fTo be accurate, the temporary thermal rod 22 is selectively arranged, complete refreezing of the foundation is realized before construction, cold energy is reserved in advance to balance thermal disturbance in the construction and operation period, and influence on highway operation is reduced.

[0118] The above merely provides the preferred embodiments of the present application, but not for limiting the present application. Any modification, equivalent replacement, and improvement made in the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An assembled cold-constructed subgrade structure, characterized by The application relates to a prefabricated roadbed module and a prefabricated roadbed. The prefabricated roadbed module comprises a bottom structure, an upper structure and a heat rod array. The bottom structure comprises a plurality of prefabricated roadbed modules (1) arranged along the lateral direction of the roadbed and a plurality of filling sections (8) arranged between two adjacent prefabricated roadbed modules (1) along the longitudinal direction of the roadbed. The bottom of the prefabricated roadbed module (1) is embedded into the foundation (3), and the filling section (8) is arranged between two adjacent prefabricated roadbed modules (1) along the longitudinal direction of the roadbed.

2. An assembled cold sink substructure according to claim 1, wherein, A plurality of installation holes (101) are arranged on the bottom of the prefabricated roadbed module (1) along the length direction of the prefabricated roadbed module (1). A ventilation channel (102) is arranged in the prefabricated roadbed module (1) along the length direction of the prefabricated roadbed module (1).

3. An assembled cold sink substructure according to claim 2, wherein, The ventilation channel (102) is connected with all the installation holes (101) of the prefabricated roadbed module (1). The ventilation channel (102) comprises an air inlet and an air outlet which are connected with the outside of the roadbed.

4. The cold-assembly subgrade structure of claim 1, wherein, The upper structure is arranged above the bottom structure.

5. A cold-assembly subgrade structure according to claim 1, wherein The heat rod array comprises a plurality of permanent heat rods (21) arranged in the installation holes (101). The upper condensation section of the permanent heat rod (21) extends into the ventilation channel (102), and the lower evaporation section of the permanent heat rod (21) extends below the permafrost table in the foundation (3). All the permanent heat rods (21) are arranged in the roadbed through the prefabricated roadbed module (1). The prefabricated roadbed module (1) has a square, rectangular or trapezoidal cross section. The ventilation channel (102) has a rectangular, circular or elliptical cross section. The prefabricated roadbed module (1) comprises a bottom plate (11) and an upper cover part. The bottom plate (11) is arranged along the lateral direction of the roadbed and is provided with the installation holes (101). The bottom plate (11) is provided with installation grooves (111) on both sides along the longitudinal direction of the roadbed. The installation grooves (111) are arranged along the lateral direction of the roadbed and are located on both sides of the installation holes (101). The upper cover part comprises a top plate (12) and two side plates (13) arranged along the longitudinal direction of the roadbed. The side plates (13) can be inserted into the installation grooves (111) on the corresponding side. The bottom plate (11), the top plate (12) and the two side plates (13) form the ventilation channel (102). Alternatively, the prefabricated roadbed module (1) comprises two groove-shaped members (14). The openings of the two groove-shaped members (14) are arranged oppositely and along the longitudinal direction of the roadbed. The bottom of the two groove-shaped members (14) is provided with a plurality of opposite semicircular notches (1011). The opposite semicircular notches (1011) are combined to form the installation hole (101). The top of the ventilation channel (102) is provided with a heat insulation plate (15). At least two prefabricated roadbed modules (1) are arranged continuously along the lateral direction of the roadbed. The two prefabricated roadbed modules (1) are connected with each other through grouting.

6. An integrated cold sink subgrade structure according to claim 1, wherein, The air inlet and the air outlet are arranged at the two end faces of the assembled subgrade module (1) in the length direction; And / or, the superstructure is sequentially provided with a cushion layer (4), a bidirectional geogrid (5) and a pavement structure layer (6) from bottom to top, the lateral sides of the cushion layer (4) and the pavement structure layer (6) are provided with side slopes (7), and the lateral distance between the permanent heat rod (21) installed on the lateral sides of the subgrade and the toe of the side slope (7) on the corresponding side is not less than 0.5m; And / or, the assembled subgrade module (1) is made of a combination of one or more of reinforced concrete, building solid waste, industrial solid waste and foamed concrete; And / or, the filling section (8) is made of a combination of one or more of filling soil, gravel and sand.

7. A method of constructing an assembled cold-embankment structure, characterized by, A method for constructing an assembled cold-conducting subgrade structure as claimed in any one of claims 1-6, comprising the following steps: S01, level the site, mark all the hot rods in the construction site; when the active layer completely frozen time t f greater than the construction period required to freeze time t d , hot rod includes a number of permanent hot rod (21) and a number of temporary hot rod (22); when the active layer completely frozen time t f less than or equal to the construction period required to freeze time t d , hot rod includes a number of permanent hot rod (21); S02, installing all the heat rods at the indicated positions so that the evaporation end of the heat rod is inserted below the upper limit of frozen soil in the natural foundation; S03, when the time t required for the active layer to completely freeze f greater than the time t required for the active layer to completely freeze d , the temporary heat rod (22) added during the construction period is removed after t d , the heat rod hole of the temporary heat rod (22) is backfilled, and then the prefabricated roadbed module (1) is installed; when the time t required for the active layer to completely freeze f is less than or equal to the time t required for the active layer to completely freeze d , the prefabricated roadbed module (1) is installed after t f . S04, constructing the filling section (8); S05, constructing the superstructure.

8. A design method for construction of an assembled cold- insulated roadbed structure, characterized by A method for guiding the construction of an assembled cold-conducting subgrade structure as claimed in claim 7, comprising the following steps: S1: Calculate the annual heat transfer amount Q2 of the permanent heat rod (21) and the arrangement pitch s of the permanent heat rod (21) under the design condition by the energy balance method s ; and calculate the cold energy requirement Q1 for completely refreezing the active layer of the natural ground (3) S2: annual heat transfer amount Q2 of the permanent heat rod (21), arrangement interval s of the permanent heat rod (21) s and the cold energy requirement amount Q1 for completely thawing the active layer of the natural foundation (3) to calculate the time t required for complete thawing of the active layer f , the time t required for complete thawing of the active layer f The calculation formula is: S3: judging whether the time t required for the active layer to completely freeze is greater than the time t required for the active layer to completely freeze during construction f S4: if yes, determining the number m of temporary heat rods (22) and the center distance s between adjacent temporary heat rods (22) on the roadbed cross section that need to be added during construction, and guiding the construction of permanent heat rods (21) and temporary heat rods (22) according to the distance s between permanent heat rods (21), the number m of temporary heat rods (22) and the center distance s between adjacent temporary heat rods (22); if no, guiding the construction of permanent heat rods (21) according to the distance s between permanent heat rods (21) d s s ; if yes, determining the number m of temporary heat rods (22) and the center distance s between adjacent temporary heat rods (22) on the roadbed cross section that need to be added during construction, and guiding the construction of permanent heat rods (21) and temporary heat rods (22) according to the distance s between permanent heat rods (21), the number m of temporary heat rods (22) and the center distance s between adjacent temporary heat rods (22); if no, guiding the construction of permanent heat rods (21) according to the distance s between permanent heat rods (21)​​ 9. The design method for construction of an assembled cold- sink subgrade structure according to claim 8, characterized in that, In step S1, the calculation formula of the cold energy requirement Q1 for completely thawing the active layer of the natural foundation (3) is: where: n is the number of divisions of the active layer, n≥1; i is the index; H i is the thickness of the ith layer; W is the width between the slope toes of the two sides of the subgrade in the transverse direction; ρ di is the dry density of the ith layer; C i is the specific heat capacity of the ith layer; T avgi is the average ground temperature of the ith layer; T pci is the phase transition temperature of the ith layer of soil; ω i is the moisture content of the ith layer; ω iu is the immobile water content of the ith layer; L is the latent heat of crystallization or melting of ice of water.

10. The method of designing the construction of an assembled cold- insulated road base structure according to claim 8, characterized in that, In step S3, the effective radius s of the temporary heat bar (22) during construction is calculated first s The calculation formula of the effective radius s of the temporary heat bar (22) during construction is: s ’ Where Δt is the working time of the temporary heat rod (22) in a year; t is the time variable; T s is the annual average ground temperature; T a is the annual average air temperature; d0 is the outer diameter of the temporary heat rod (22); R a is the thermal resistance of the temporary heat rod (22); λ f is the thermal conductivity of the fin of the temporary heat rod (22); L e is the length of the evaporation section of the temporary heat rod (22); Then, the number m of the temporary heat bars (22) on the cross section of the roadbed is calculated according to the effective radius s of the temporary heat bar (22) s The number m of the temporary heat bars (22) on the cross section of the roadbed is calculated according to the effective radius s of the temporary heat bar (22) Where W is the width between the toes of the lateral sides of the subgrade; and according to the effective radius s of the temporary thermal probe (22) s the center distance s between adjacent temporary thermal probes (22) is calculated from the arrangement of the temporary thermal probes (22) wherein, when the arrangement of the newly added temporary thermal rods (22) is a square, s = s s ' / 1.128; when the arrangement of the newly added temporary thermal rods (22) is an equilateral triangle, s = s s ' / 1.05.

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