Pile-raft integrated roadbed and pavement structure in permafrost region and construction method thereof

Abstract

The application discloses a kind of high temperature permafrost area pile raft surface integration roadbed pavement structures, including high temperature permafrost layer, season active layer, embankment reinforcement area, cast-in-place pile, cushion layer, heat insulation layer, reinforced concrete raft, asphalt surface layer and pile top inverted umbrella-shaped steel hook.Embarkment reinforcement area, cushion layer, heat insulation layer, reinforced concrete raft, asphalt surface layer are sequentially laid above season active layer from bottom to top;Cast-in-place pile is arranged at intervals, and vertically passes through heat insulation layer, cushion layer, embarkment reinforcement area, season active layer and is driven into high temperature permafrost layer;Pile top inverted umbrella-shaped steel hook and the pile top of cast-in-place pile are poured in reinforced concrete raft together, and form pile-plate rigid joint integration.The application can solve the deformation problem caused by frozen soil degradation, active layer high frequency repeated freeze-thaw, embankment fill differential settlement of high-altitude high temperature permafrost area highway, overcome the deficiency of horizontal stiffness, bending stiffness and shear stiffness of traditional raft roadbed.

Description

Technical Field

[0001] This invention belongs to the field of roadbed maintenance technology in permafrost regions, and specifically relates to an integrated pile-raft roadbed and pavement structure and its construction method in high-temperature permafrost regions. Background Technology

[0002] Roadbed subsidence in the high-altitude, high-temperature, and high-ice-content permafrost region of the Qinghai-Tibet Plateau has long been a problem that has been difficult to solve effectively. The main reason for roadbed subsidence is the continuous degradation and subsidence of the underlying deep permafrost layer with high temperature and high ice content. Existing active roadbed cooling engineering measures, such as heat pipe roadbeds, ventilation pipe roadbeds, rubble roadbeds, and insulation board roadbeds, cannot effectively control and adapt to the potential large deformation of the foundation. According to the results of field investigation, these measures are more effective for low-temperature (<-2℃) permafrost, but less effective for high-temperature (-2℃~0℃) permafrost, which is prone to degradation.

[0003] The invention patent CN108265735A proposes a raft-pile composite foundation for highway subgrade in high-latitude, high-temperature permafrost regions. Its core requirement is that the pile foundation needs to penetrate the permafrost layer to reach the bedrock bearing layer, adapting to the thin permafrost layer characteristic of high-latitude foundations. However, the high-altitude permafrost region of the Qinghai-Tibet Plateau has a large amount of high-temperature permafrost layers with a thickness of tens of meters or more, and the cost of penetrating them is unacceptable.

[0004] The invention patent CN111364495A has a structural design that is effective in addressing earthquake damage deformation and frost heave of building foundations in cold regions. However, in the long strip roads of the high-temperature permafrost region of Northwest China, this invention structure is difficult to bear heavy loads year-round. Secondly, the design cost is high, the transportation of raw materials is difficult, and the pile-raft structure is not an integrated structure. Instead, the load is distributed through the cushion layer under the raft slab, making it extremely difficult to adapt to the harsh conditions of high-altitude road construction and operation.

[0005] The invention patent CN115075281B has a structural design intended to block the thermal disturbance of the frozen soil around the pile caused by the release of CFG pile hydration heat during the pile foundation construction process. The blocking design is extremely complicated. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated pile-raft roadbed and pavement structure and its construction method in high-temperature permafrost areas. This invention addresses the deformation problems caused by permafrost degradation, frequent freeze-thaw cycles of the active layer, and differential settlement of embankment fill in highways in high-altitude, high-temperature permafrost areas. It overcomes the shortcomings of traditional pile foundations in raft slabs, such as discontinuous pile cap structures, complex construction processes, and high construction costs in high-altitude conditions. It also overcomes the deficiencies in horizontal stiffness, bending stiffness, and shear stiffness of traditional raft slab roadbeds.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A pile-raft-surface integrated roadbed and pavement structure for high-temperature permafrost regions includes a high-temperature permafrost layer, a seasonally active layer, an embankment reinforcement zone, bored piles, a cushion layer, a heat insulation layer, a reinforced concrete raft slab, an asphalt surface layer, and an inverted umbrella-shaped rigid hook at the pile top.

[0009] In the roadbed and pavement structure of this invention, the high-temperature permafrost layer is a soil layer with a temperature between -1.5 and 0°C and frozen for two years or more, also known as near-phase change zone permafrost; the seasonally active layer is a soil layer that thaws in summer and freezes in winter; the embankment reinforcement zone is artificially compacted fill on the surface, laid above the seasonally active layer; the cushion layer is laid below the insulation layer and above the embankment reinforcement zone; the reinforced concrete raft slab is formed by an integral steel frame and C40 concrete grouting, located above the insulation layer; the asphalt surface layer is asphalt concrete, laid on the reinforced concrete raft slab; the bored piles are arranged at intervals and vertically penetrate the insulation layer, cushion layer, embankment reinforcement zone, and seasonally active layer into the high-temperature permafrost layer; the inverted umbrella-shaped rigid hook at the pile top connects to the pile top of the bored pile and is cast together with the pile top in the integral steel frame inside the reinforced concrete raft slab, forming a rigid integrated pile-slab connection.

[0010] As a further explanation of the present invention, the bored cast-in-place pile is a bored cast-in-place concrete pile manufactured using rotary drilling technology, with a pile length of less than 15m, a diameter of more than 0.8m, and a pile spacing of more than 4m. The bored cast-in-place concrete pile contains a specially positioned reinforcing cage; the specially positioned reinforcing cage includes vertical main reinforcing bars, stirrups, and positioning reinforcing bars; the vertical main reinforcing bars are arranged in a circular array; the stirrups are tied to the vertical main reinforcing bars in a circular pattern from top to bottom; the positioning reinforcing bars are arranged in groups of 4 every 2 to 5 meters.

[0011] As a further explanation of the present invention, the inverted umbrella-shaped rigid hook at the pile top is an extension of the vertical main reinforcing bar of a specially positioned reinforcing cage, or is connected to the top of the vertical main reinforcing bar by welding or threaded connection. The material of the inverted umbrella-shaped rigid hook at the pile top is high-strength corrosion-resistant steel, which is cast together with the pile top of the bored cast-in-place pile in the overall reinforced steel frame structure inside the reinforced concrete raft slab to form an integrated pile-raft structure.

[0012] As a further explanation of the present invention, the thickness of the reinforced concrete raft slab is 30-50 cm, the joint length of the slabs can be 10 meters, and 4-9 bored piles are laid at the bottom of each reinforced concrete raft slab; a 1 cm wide expansion joint should be set at the joint of two reinforced concrete raft slabs, and the joint should be filled with insulation board or other soft materials.

[0013] As a further explanation of the present invention, the overall steel reinforcement frame of the reinforced concrete raft slab includes a hidden beam, panel reinforcement bars, and horizontal and vertical steel bars; the hidden beam is a steel reinforcement frame with external stirrups spaced 10 cm apart and tied to the steel bars with wire; the panel reinforcement bars are steel bars with a diameter of 20 mm; the intersections of the horizontal and vertical steel bars are tied together with thin binding wire.

[0014] As a further explanation of the present invention, the embankment reinforcement area is constructed by piling up soil to a certain height (the specific height is determined according to the roadbed design height) on the natural surface and manually compacting it. The compaction degree should be ≥95%, and the surface should be smooth after the compaction degree meets the requirements. The bedding layer is made of sand or gravel, with a thickness of 20-40 cm. When laying the bedding layer, a layer of bidirectional geogrid and geotextile should be laid first on the leveling layer of the embankment reinforcement area, followed by the bedding layer, and then the upper layer of geogrid or geotextile, which is then compacted. The heat insulation layer is made of high-performance polystyrene resin mixed with foaming agents, anti-aging agents, and other additives in a certain proportion and extruded, or other high-performance heat-insulating materials. The asphalt surface layer is made of frost-resistant and UV-resistant asphalt concrete material, with a thickness of more than 10 cm.

[0015] This invention also provides a construction method for the above-mentioned integrated pile-raft roadbed and pavement structure in high-temperature permafrost regions, comprising the following steps:

[0016] a. Site leveling;

[0017] b. Lay a gravel cushion layer (embankment reinforcement area);

[0018] c. Rotary drilling rig enters the site and drills positioning holes;

[0019] d. Binding and lowering of specially positioned reinforcing cages inside the pile foundation;

[0020] e. After drilling, pour concrete.

[0021] f. Break the pile head according to the design elevation and install the inverted umbrella-shaped rigid hook on the pile top;

[0022] g. Laying bidirectional geogrid mesh, geotextile and mattress layer;

[0023] h. Install high-performance thermal insulation layers;

[0024] i. Binding the raft slab reinforcement, hidden beams and reinforcement mesh, and erecting formwork;

[0025] j. Raft foundation concrete pouring and curing;

[0026] K. Asphalt surface layer pouring and curing maintenance.

[0027] Advantages of this invention:

[0028] 1. A pile-raft-surface integrated subgrade and pavement structure provided by the present invention in a high-altitude, high-temperature permafrost area: Piles are used as reinforcement bodies to form a bearing system together with the soil around the piles and the raft foundation; compared with the single-pile single-cap structure of other pile rafts, the inside of the raft above the piles in the present invention is a closed "field" shape composed of a steel bar framework, and then steel bar meshes are tied on the upper and lower surfaces of the framework. The inverted umbrella-shaped hook at the top of the pile is rigidly connected to the hidden beam framework in the raft to form an integrated body. After pouring, the pile-raft integrated structure can greatly improve the overall bearing capacity of the subgrade. The soil arch effect formed by the piles can radiate the soil between the piles under the raft in a larger range, enabling the piles and the soil to reasonably share the load.

[0029] 2. The present invention saves the force transmission process of the embankment fill. The upper load is directly borne by the piles and the soil between the piles, making the designed structure have higher bearing efficiency and reducing the subgrade settlement deformation caused by the compression of the embankment fill. The cushion layer and the high-performance heat insulation layer can both block the intrusion of external heat of the subgrade, and effectively solve the subgrade deformation problems caused by permafrost degradation, high-frequency repeated freezing and thawing of the active layer, insufficient soil arch effect of the pile foundation, and differential settlement of the embankment fill in the highway corridor belt pile-raft structure roadbed.

[0030] 3. The heat insulation layer of the present invention selects a high-performance XPS insulation board or other thermal resistance materials. It is an extruded polystyrene insulation board, which is made of polystyrene resin as the raw material, plus butane foaming agent and flame retardant and other additives, and is extruded and formed into a rigid foam plastic board by heating and stirring while adding a catalyst. Its extremely low thermal conductivity can effectively block heat transfer, provide excellent thermal insulation performance, isolate the heat conduction of the ground, keep the subgrade temperature stable, and reduce the frost heave or thaw settlement phenomenon of the subgrade caused by temperature changes; its high compressive strength and durability can ensure that the insulation board maintains its performance in the harsh plateau construction environment and bears the heavy load of the road surface without deformation, which is sufficient to cope with the plateau heavy load and high-load environment, and配合 the cushion layer can evenly disperse the load to the piles to improve the stability of the subgrade; its closed-cell structure results in low water absorption, improves the drainage performance, and is not easily damaged in the freeze-thaw cycle; it also has the advantages of being light, environmentally friendly, non-toxic and harmless, recyclable, etc., and is suitable for the plateau construction requirements in all aspects.

[0031] 4. This invention optimizes the pile diameter, pile spacing, hidden beam structure, and raft foundation reinforcement ratio. The pile length is shortened to within 15m while allowing the piles to be located in high-temperature frozen soil layers. The pile spacing is increased to over 4m, meaning that only 3 piles are needed in the cross-section of the roadbed to meet deformation control requirements. Compared to patent CN108265735A, this significantly reduces the amount of underground engineering and process complexity, making it suitable for harsh high-altitude climates and complex geological environments. Compared to the drilled and driven precast pile technology used in patent CN108265735A, this invention uses drilled cast-in-place piles. Due to the significantly increased freezing force at the pile-soil interface, the number of piles is reduced while ensuring the bearing capacity meets requirements. Furthermore, this invention adds hidden beams within the raft foundation, connecting the piles in each unit into a single unit, which better adapts to differential settlement caused by uneven degradation of high-temperature frozen soil. Compared to the invention patent CN115075281B, the bored pile concrete mentioned in this invention can use low-heat cement to control the heat of hydration of the concrete, and can easily and simply protect the frozen soil around the pile. Attached Figure Description

[0032] Figure 1 This is a cross-sectional schematic diagram of an integrated pile-raft roadbed and pavement structure in a high-temperature permafrost region according to an embodiment of the present invention.

[0033] Figure 2 This is a top view schematic diagram of the inverted umbrella-shaped hook and wavy geogrid embedded on the top surface of the pile foundation in the integrated pile-raft roadbed and pavement structure in a high-temperature permafrost region according to an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the internal steel mesh of the raft slab in an integrated pile-raft roadbed and pavement structure in a high-temperature permafrost region according to an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the rigid pile reinforcement cage and the inverted umbrella-shaped rigid structure of the pile body in the integrated pile-raft roadbed and pavement structure in high-temperature permafrost areas according to an embodiment of the present invention.

[0036] In the attached diagram, A-natural ground, 1-high temperature permafrost layer, 2-seasonal active layer, 3-embankment reinforcement zone, 4-drilled pile, 41-specially positioned reinforcing cage, 411-stirrups, 412-vertical main reinforcing bars, 413-positioning reinforcing bars, 5-cushion layer, 6-insulation layer, 7-reinforced concrete raft slab, 71-hidden beam, 72-face panel reinforcement, 73-horizontal and longitudinal reinforcing bars, 8-asphalt surface layer, 9-pile top inverted umbrella-shaped rigid hook. Detailed Implementation

[0037] The following detailed description of the technical solution of the present invention, in conjunction with the accompanying drawings and specific embodiments, will not constitute a limitation thereof. The advantages of the present invention will become clearer and easier to understand through this description.

[0038] Example: An integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions, such as... Figure 1 The structure includes: 1. High-temperature permafrost layer; 2. Seasonally active layer; 3. Embankment reinforcement zone; 4. Drilled piles; 5. Cushion layer; 6. Insulation layer; 7. Reinforced concrete raft foundation; 8. Asphalt surface layer; and 9. Inverted umbrella-shaped rigid hook at the pile top.

[0039] The high-temperature permafrost layer 1 is a soil layer with a temperature between -1.5 and 0℃ and frozen for two years or more, also known as permafrost in the near-phase change zone; the seasonally active layer 2 is a soil layer that thaws in summer and freezes in winter; the embankment reinforcement zone 3 is artificially compacted fill on the surface, laid above the seasonally active layer 2; the cushion layer 5 is laid below the insulation layer 6 and above the embankment reinforcement zone 3; the reinforced concrete raft slab 7 is formed by an integral steel frame and C40 concrete grouting, located above the insulation layer 6; the asphalt surface layer 8 is asphalt concrete, laid on the reinforced concrete raft slab 7; the bored piles 4 are arranged at intervals and vertically penetrate the insulation layer 6, cushion layer 5, embankment reinforcement zone 3, and seasonally active layer 2 into the high-temperature permafrost layer 1; the inverted umbrella-shaped rigid hook 9 at the pile top connects to the pile top of the bored pile 4 and is cast together with the pile top in the integral steel frame inside the reinforced concrete raft slab 7, forming a rigid integrated pile-slab connection.

[0040] This embodiment further illustrates that the bored pile 4 is a bored cast-in-place concrete pile manufactured using rotary drilling technology. The pile length is 5–15 m, determined after geological survey based on the upper limit of artificial soil depth in permafrost and the underlying bearing layer. The pile diameter is 0.2–0.8 m. The longitudinal and transverse spacing of the piles is set at 3–6 times the pile diameter, with the vertical spacing penetrating the seasonally active layer and driving into the permafrost bearing layer. The distance between the center of the bored pile and the edge of the foundation should not be less than 1 times the pile diameter; the distance between the edge of the pile and the edge of the foundation (strip foundation) should not be less than 75 mm. The pile length should allow the pile tip to penetrate the more compressible active soil layer and enter the relatively less compressible permafrost layer. The bored cast-in-place concrete pile contains a specially positioned reinforcing cage 41; as shown... Figure 4 As shown, the specially positioned reinforcing cage 41 includes vertical main reinforcing bars 412, stirrups 411 and positioning reinforcing bars 413; the vertical main reinforcing bars 412 are arranged in a ring array; the stirrups 411 are tied to the vertical main reinforcing bars in a ring from top to bottom; the positioning reinforcing bars 413 are arranged in groups every 2 to 5 meters, with 4 bars evenly arranged in each group.

[0041] This embodiment further illustrates that the inverted umbrella-shaped rigid hook 9 at the top of the pile is connected to the top of the vertical main reinforcing bar 412 by welding.

[0042] This embodiment further illustrates, as follows: Figure 2As shown, the thickness of the reinforced concrete raft slab 7 is 30-50 cm, and the joint length of the slabs can be 10 meters. 4-9 bored piles 4 are laid at the bottom of each reinforced concrete raft slab 7. A 1 cm wide expansion joint should be set at the joint of two reinforced concrete raft slabs, and the joint should be filled with insulation board or other soft materials.

[0043] This embodiment further illustrates, as follows: Figure 3 As shown, the overall steel reinforcement frame of the reinforced concrete raft slab 7 includes a hidden beam 71, a panel reinforcing bar 72, and horizontal and vertical reinforcing bars 73; the hidden beam 71 is a steel reinforcement frame with external stirrups spaced 10 cm apart and tied to the reinforcing bars with wire; the panel reinforcing bar 72 is a reinforcing bar with a diameter of 20 mm; the intersections of the horizontal and vertical reinforcing bars 73 are tied together with thin binding wire.

[0044] This embodiment further illustrates that the embankment reinforcement zone 3 is formed by piling up soil on the natural surface and manually compacting it. The compaction degree should be ≥95%, and the surface should be flat after the compaction degree meets the requirements.

[0045] This embodiment further illustrates that the paving material of the mattress layer 5 is medium sand, coarse sand, and well-graded crushed stone. The maximum particle size of the sand and gravel should not exceed 30mm, and the paving thickness is 20-40cm. When laying the mattress layer 5, a layer of bidirectional geogrid and geotextile should be laid first in the leveling layer of the embankment reinforcement area 3, followed by the mattress layer, and then the upper layer of geogrid or geotextile, and compacted.

[0046] This embodiment further illustrates that the heat insulation layer 6 is made of high-performance polystyrene resin mixed with foaming agent and anti-aging agent in proportion and extruded, or other high-performance heat-insulating materials; the asphalt surface layer 8 is frost-resistant and UV-resistant asphalt concrete material with a paving thickness of more than 10 cm.

[0047] In this embodiment, the specific implementation process for the construction of bored cast-in-place concrete piles in high-temperature permafrost regions is as follows:

[0048] ① Before construction, understand the permafrost geological survey data of the construction site, prepare the construction organization design, and complete the preparation of raw materials and emergency measures required for the drilling and grouting process; ② After marking the hole position, the drilling rig should be brought to the site, positioned, and properly debugged; ③ Prepare mud slurry for wall protection and slag removal, inject clean water and additives, and use native soil to make mud slurry for wall protection; ④ During drilling, pay attention to the machine's operating status, observe the borehole opening and surrounding area for any abnormalities, ensure that the machine arm operates within a certain range, and control the borehole inclination within the standard range, and promptly remove the native soil from the borehole; ⑤ After the hole is completed, stop drilling after the hole depth, diameter, and inclination are tested and found to be qualified; ⑥ Prepare the reinforcing cage. After the length, diameter, and welding condition are inspected and found to meet the standards, the reinforcing cage is hoisted into the hole; ⑦ Concrete is poured using a duct. For a pile diameter of 60cm, a 200mm diameter duct with a wall thickness of 3-5mm is used, keeping the inner wall smooth, with a throughput capacity of 10m³ / h; the duct is sealed with a quick connector, and cleaned promptly after pouring; ⑧ After the concrete has solidified, the borehole shape is repaired. When the concrete reaches a certain strength, a low-strain dynamic test is used to check the integrity of the pile body; the detailed operating procedure should be determined based on the actual situation of the engineering site. This procedure only describes some of the main operations in the implementation of this invention.

[0049] At the same time, the reinforced concrete cast-in-place pile contains a specially positioned reinforcing cage (such as...). Figure 4 The specially designed positioning reinforcement cage includes vertical main reinforcement bars, stirrups, and positioning reinforcement bars. The vertical main reinforcement bars are arranged in a circular array. The stirrups are tied to the vertical main reinforcement bars in a circular pattern from top to bottom. The positioning reinforcement bars are arranged in groups of 4 bars every 2m. The lap joints of the reinforcement bars are welded on one side. The main reinforcement bars are connected by steel sleeve connectors or butt welds. The allowable deviation of the reinforcement cage diameter is ±10mm, and the allowable deviation of the reinforcement cage length is ±100mm. The inverted umbrella-shaped rigid hook at the pile top is installed after the bedding layer is laid. Its connection to the reinforcement cage can be welding or threaded assembly.

[0050] The cushion layer material is medium-coarse sand or gravel, with a thickness of 20-40cm. When laying the cushion layer, a layer of geogrid should be laid first on the pile top leveling layer, and then the material should be spread. A high-strength corrugated geogrid should be added at the center position below the pile raft slab. If the soil properties of the construction site are poor, a layer can be laid at the bottom and middle of the cushion layer, and then geotextile can be laid and compacted.

[0051] The insulation layer uses XPS insulation board or other high-performance heat-insulating materials. The insulation board is extruded polystyrene insulation board, which is a rigid foam plastic board made of polystyrene resin as raw material, with butane foaming agent and flame retardant and other additives. It is formed by extrusion molding through heating and stirring while adding catalyst. Its extremely low thermal conductivity can effectively block heat transfer, providing excellent thermal insulation performance, isolating ground heat conduction, maintaining the stability of the roadbed temperature, and reducing the occurrence of frost heave or thaw settlement due to temperature changes. Its high compressive strength and durability can ensure that the insulation board maintains its performance in the harsh high-altitude construction environment and can withstand heavy road loads without deformation, improving the stability of the roadbed.

[0052] The main construction techniques for reinforced concrete raft slabs include:

[0053] 1. The road surface smoothness and excess steel reinforcement in the pile foundation are within permissible limits.

[0054] 2. Design the raft foundation frame based on the pile hole locations, and then place the internal steel reinforcement of the horizontal and vertical raft foundation based on the frame foundation;

[0055] 3. After the reinforcing bars are tied, concrete is poured evenly into all parts of the panel using a guide pipe, and a concrete vibrator is used to compact it and increase its strength. A floor trowel is used to treat the concrete pavement to achieve the required flatness. After it has solidified and been set for a period of time, a quality inspection is carried out.

[0056] The reinforced concrete raft slab is a C40 cast-in-place frost-resistant concrete slab, 50cm thick, 10m long, with a 1cm joint width. It is immediately covered and cured after pouring, and the road structure layer is laid after the raft slab concrete reaches its design strength; raft slab (such as...) Figure 2 , Figure 3 It includes hidden beams, panel reinforcement bars, and horizontal and vertical steel bars; the hidden beams are steel frame with external stirrups spaced 10cm apart and tied to the steel bars with iron wire; the intersections of the horizontal and vertical steel bars are tied together with thin binding wire; the inverted umbrella-shaped rigid hooks at the top of the pile are made of corrosion-resistant high-strength material, which can be directly welded to the steel cage inside the pile or connected by threaded interface, and poured into the rigid raft slab.

[0057] Obviously, the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description; it is neither necessary nor possible to exhaustively list all possible implementations; however, obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A pile-raft roadbed and pavement integrated structure for high-temperature permafrost regions, characterized in that... include: High-temperature permafrost layer (1), seasonally active layer (2), embankment reinforcement zone (3), bored pile (4), cushion layer (5), heat insulation layer (6), reinforced concrete raft slab (7), asphalt surface layer (8) and inverted umbrella-shaped rigid hook at the top of the pile (9). The high-temperature permafrost layer (1) is a soil layer with a temperature between -1.5 and 0℃ and frozen for two years or more, also known as permafrost in the near-phase change zone; The seasonally active layer (2) is a soil layer that melts in summer and freezes in winter; The embankment reinforcement area (3) is artificially compacted fill on the ground surface, laid on top of the seasonal activity layer (2); The mattress layer (5) is laid below the insulation layer (6) and above the embankment reinforcement area (3); The reinforced concrete raft slab (7) is cast in place from an integral steel frame and C40 concrete grout, and is located above the insulation layer (6); The asphalt surface layer (8) is asphalt concrete, which is laid on the reinforced concrete raft slab (7); The bored piles (4) are arranged at intervals and are driven vertically through the insulation layer (6), the cushion layer (5), the embankment reinforcement zone (3), and the seasonal activity layer (2) into the high-temperature permafrost layer (1); The inverted umbrella-shaped rigid hook (9) at the top of the pile connects to the top of the bored pile (4) and is cast together with the top of the pile in the overall steel frame inside the reinforced concrete raft slab (7) to form a rigid integrated pile-slab connection. The bored pile (4) is a bored concrete pile using rotary drilling technology, with a pile length of less than 15m, a diameter of more than 0.8m, and a pile spacing of more than 4m; the bored concrete pile contains a specially positioned reinforcing cage (41); the specially positioned reinforcing cage (41) includes vertical main reinforcing bars (412), stirrups (411), and positioning reinforcing bars (413); the vertical main reinforcing bars (412) are arranged in a ring array; the stirrups (411) are tied to the vertical main reinforcing bars in a ring from top to bottom; the positioning reinforcing bars (413) are set in groups every 2 to 5 meters, with 4 bars evenly arranged in each group.

2. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1, characterized in that: The inverted umbrella-shaped rigid hook (9) at the top of the pile is an extension of the vertical main reinforcement (412) of the specially positioned reinforcement cage (41), or is connected to the top of the vertical main reinforcement (412) by welding or threaded connection.

3. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1, characterized in that: The thickness of the reinforced concrete raft slab (7) is 30-50 cm, and the joint length of the slab can be 10 meters. 4-9 bored piles (4) are laid at the bottom of each reinforced concrete raft slab (7). A 1 cm wide expansion joint should be set at the joint of two reinforced concrete raft slabs, and the joint should be filled with insulation board or other soft materials.

4. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1 or 3, characterized in that: The overall steel reinforcement frame of the reinforced concrete raft slab (7) includes a hidden beam (71), a panel reinforcement (72), and horizontal and vertical steel bars (73); the hidden beam (71) is a steel reinforcement frame with an external stirrup spacing of 10 cm, which is tied to the steel bars with iron wire; the panel reinforcement (72) is a steel bar with a diameter of 20 mm; the intersection of the horizontal and vertical steel bars (73) is tied together with thin binding wire.

5. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1, characterized in that: The embankment reinforcement area (3) is to pile up soil on the natural ground surface and compact it manually. The compaction degree should be ≥95%. After the compaction degree meets the requirements, the surface should be flat.

6. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1, characterized in that: The paving material of the mattress layer (5) is sand or gravel, and the thickness is 20-40 cm. When laying the mattress layer (5), a layer of bidirectional geogrid and geotextile should be laid first in the leveling layer of the embankment reinforcement area (3), then the mattress layer is laid, and then the upper layer of geogrid or geotextile is laid and compacted.

7. The integrated pile-raft roadbed and pavement structure for high-temperature permafrost regions according to claim 1, characterized in that: The heat insulation layer (6) is made of high-performance polystyrene resin mixed with foaming agent and anti-aging agent in proportion and extruded, or other high-performance heat-insulating materials; the asphalt surface layer (8) is frost-resistant and UV-resistant asphalt concrete material with a paving thickness of more than 10 cm.

8. A construction method for an integrated pile-raft roadbed and pavement structure in high-temperature permafrost regions as described in any one of claims 1-7, characterized in that... Includes the following steps: a. Site leveling; b. Lay a gravel cushion layer; c. Rotary drilling rig enters the site and drills positioning holes; d. Binding and lowering of specially positioned reinforcing cages inside the pile foundation; e. After drilling, pour concrete; f. Break the pile head according to the design elevation and install the inverted umbrella-shaped rigid hook on the pile top; g. Laying bidirectional geogrid mesh, geotextile and mattress layer; h. Install high-performance thermal insulation layers; i. Binding the raft slab reinforcement, hidden beams and reinforcement mesh, and erecting formwork; j. Raft slab concrete pouring and curing; K. Asphalt surface layer pouring and curing maintenance.

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