Rail transit protection area road zero load transmission construction method

Abstract

The invention discloses a zero-load transmission construction method for a road in a rail transit protection area, which is characterized in that through the double-modulus layer design of EPS blocks and floor beams, the EPS blocks are used for gradient replacement and filling, the EPS density is small, and basalt fibers are added, so that the strength is greatly improved, the requirements of replacement and filling materials can be met, and the construction method has the characteristics of light weight, small density, high strength, high strength and the like. The structure has certain controllable deformation characteristics, a controllable deformation space is formed by utilizing the pre-pressed dense EPS layer, external load is actively absorbed, and the structure meets the road zero load of a rail traffic protection area through a composite force transmission path of vertical EPS energy consumption and horizontal floor beam flow guide.

Description

Technical Field

[0001] This invention relates to the field of road construction technology, specifically to a zero-load transfer construction method for roads in rail transit protection zones. Background Technology

[0002] In existing urban transportation systems, subway tunnels, viaducts, and high-speed trains are ubiquitous, greatly facilitating people's travel. However, these tracks are extremely sensitive to changes in the surrounding ground load. Overloading, excavation, or vibration within the track protection zone can lead to uneven settlement, tunnel deformation, or track displacement, directly threatening the operational safety of the train. Therefore, when constructing roads within the track protection zone, it is essential to minimize the ground load as much as possible, ideally achieving zero load.

[0003] When constructing roads near the tracks, material replacement is required. However, traditional replacement materials with excessive density can cause stress exceeding the standard, resulting in insufficient load on the roads and affecting track safety. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a zero-load transfer construction method for roads in rail transit protection zones. This method solves the problem that when constructing roads near the track, material replacement is required, but traditional replacement materials with excessive density can lead to excessive stress, resulting in insufficient load on the road and affecting track safety.

[0005] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution:

[0006] A method for zero-load transfer construction of roads in rail transit protection zones, comprising the following steps:

[0007] S1. Earthwork excavation: The open-cut method is adopted. The middle soil is excavated first in the horizontal direction, and then the soil on both sides is excavated. The longitudinal direction is excavated according to the zone. The excavation length of each section of the foundation pit corresponds to the zone. The vertical direction is excavated in layers from top to bottom.

[0008] S2. Excavate the existing road laterally to 0.6m, then excavate the existing road with a width of 0.5m. When overlapping, the existing road surface structure needs to be removed with a width of 0.5m. A 0.5m wide fiberglass grid is laid on the surface and bottom layers of the existing road structure, and a layer of geogrid is laid on the cement-stabilized base layer.

[0009] S3. Roadbed clearing and treatment: the thickness of the clearing and treatment should not be less than 30cm, and the original ground plant roots should be removed.

[0010] S4. Laying geotextile foam blocks (EPS blocks) and ground beams:

[0011] When the road design elevation minus the existing ground elevation is ≥1.5m, a structure of ground beams + EPS blocks is adopted. Three ground beams are laid inside the roadbed along the extension direction of the roadbed. Two ground beams extend along the edge of the roadbed, and the other ground beam extends along the central axis of the roadbed. A ground beam is laid transversely every 10m, so that the roadbed pit is divided into several rectangular arrays enclosed by ground beams.

[0012] When the road design elevation minus the existing ground elevation is less than 1.5m, the EPS block full-paving structure is directly adopted;

[0013] S5. At the bottom of the rectangular array, lay geotextile foam (EPS) blocks, and lay the EPS blocks layer by layer from bottom to top with staggered joints, following the principle of from low to high and from the middle to the sides. When gaps and unevenness occur between the blocks, the bottom layer is adjusted by the pad layer, and the middle layers are leveled with non-shrink cement mortar.

[0014] S6. Lay a layer of impermeable geotextile on the top layer of the EPS block, and then pour a 15cm thick C30 reinforced concrete slab on top of the EPS block.

[0015] S7. When the concrete slab reaches 70% of its strength after drying, cover the concrete slab with 80cm thick clay for equal-load preloading.

[0016] S8. Lay motor vehicle roads and sidewalks on clay;

[0017] The road structure for motor vehicles consists of: 4cm fine-grained asphalt concrete (AC-13C) with SBS modified asphalt, 8cm coarse-grained asphalt concrete (AC-25C), 0.6cm emulsified asphalt slurry seal, 18cm cement-stabilized crushed stone (design compressive strength 4.0MPa), 18cm cement-stabilized crushed stone (design compressive strength 3.0MPa), and 15cm graded crushed stone. The total thickness of the pavement structure is 63.6cm, and the subgrade resilient modulus E0 ≥ 25MPa.

[0018] The pedestrian pavement structure consists of: 6cm permeable bricks, 3cm medium-coarse sand, 15cm C20 permeable concrete, and 10cm graded crushed stone, with a total pavement structure thickness of 34cm.

[0019] S9. For overlaying of old asphalt pavement, asphalt concrete, cement-stabilized crushed stone, graded crushed stone, and lime-soil are used as transition and leveling layers to adjust the height of the overlay.

[0020] S10. Construct slope protection using EPS blocks, with the EPS blocks laid close to the ground beams and in a staggered manner. Cover the surface of the EPS blocks with a 1.5m thick layer of soil; plant turf on the soil surface.

[0021] Preferably, in step S1, excavation is carried out in the order of segmentation-layering-symmetry-balance-time limit;

[0022] Longitudinal segmentation: The segmentation of the foundation pit excavation corresponds to the segmentation of pipeline construction. Pipeline construction is carried out in a timely manner after the last layer of soil is excavated in the foundation pit.

[0023] Vertical layering: The depth of the foundation pit excavation is divided according to the location of the support installation, and the excavation depth of each layer is about 3m;

[0024] Symmetry and balance: When excavating the foundation pit in the longitudinal direction, excavation should proceed from both ends to the middle, and the excavation of the foundation pit on both sides should be balanced to ensure that the retaining structure is evenly stressed and that the support is erected in a timely manner.

[0025] Time limit: The longitudinal excavation length of each small section of earthwork below the ring beam is 12-15m, and the excavation and support installation of the small section of earthwork must be completed within 16 hours.

[0026] Preferably, in step S3, when the roadbed is in a low-lying area and surface water or groundwater affects the roadbed filling, the base is drained by excavating a temporary drainage ditch, and then a 30cm thick sand and gravel cushion layer or slag is laid on the roadbed surface.

[0027] Preferably, in step S5, a 0.2m layer of medium-coarse sand is placed at the bottom of the EPS, with the width of the medium-coarse sand exceeding the edge of the roadbed by 1m. Permeable geotextile is laid on the top and bottom of the medium-coarse sand, and the surface is kept flat and level.

[0028] Preferably, in step S5, a double-sided claw-type connector is provided between the EPS blocks. The connector includes a rectangular structure equal to the bottom surface of the EPS block. The edge of the rectangular structure is provided with limiting teeth. The limiting teeth are vertically upward and vertically downward respectively, and the vertically upward teeth and the vertically downward teeth are staggered.

[0029] Preferably, in step S5, the EPS blocks in contact with the backfill are laid in a stepped manner.

[0030] Preferably, in step S6, the top EPS cast-in-place concrete slab extends longitudinally 1-2m into the backfill portion.

[0031] Preferably, in step S9, when the overlay height H ≤ 12.6 cm, the old pavement is milled to 12.6 cm below the design elevation, and a 4 cm fine-grained asphalt concrete (AC-13C) SBS modified asphalt + 8 cm coarse-grained asphalt concrete (AC-25C) + 0.6 cm emulsified asphalt slurry seal is laid.

[0032] When 12.6cm < overlay height H ≤ 28.6cm, the overlay consists of 4cm fine-grained asphalt concrete (AC-13C) SBS modified asphalt + 8-24cm coarse-grained asphalt concrete (AC-25C) + 0.6cm emulsified asphalt slurry seal.

[0033] When the overlay height H is less than 28.6cm and less than 48.6cm, the overlay should consist of 4cm fine-grained asphalt concrete (AC-13C) SBS modified asphalt + 8cm coarse-grained asphalt concrete (AC-25C) + 0.6cm emulsified asphalt slurry seal + 16-36cm cement-stabilized crushed stone (design compressive strength 4.0MPa).

[0034] When the overlay height H is less than 48.6cm and less than 63.6cm, the overlay should consist of 4cm fine-grained asphalt concrete (AC-13C) SBS modified asphalt + 8cm coarse-grained asphalt concrete (AC-25C) + 0.6cm emulsified asphalt slurry seal + 36~51cm cement-stabilized crushed stone (design compressive strength 4.0MPa).

[0035] When the overlay height H is less than 63.6cm and less than 83.6cm, the overlay consists of 4cm fine-grained asphalt concrete (AC-13C) SBS modified asphalt + 8cm coarse-grained asphalt concrete (AC-25C) + 0.6cm emulsified asphalt slurry seal + 36cm cement-stabilized crushed stone (design compressive strength 4.0MPa) + 15~35cm graded crushed stone.

[0036] When the height of the overlay is H > 83.6 cm, a 6% lime-soil transition should be used.

[0037] Preferably, in step S10, the soil covering the slope should be fully compacted, and the width of the soil slope protection paving should ensure that the net width after slope cutting meets the design requirements.

[0038] Preferably, the geotextile foam block is a modified EPS block with basalt fiber incorporated inside.

[0039] This invention provides a zero-load transfer construction method for roads in rail transit protection zones, which has the following beneficial effects:

[0040] 1. This invention utilizes a dual-modulus layer design of EPS blocks and ground beams. It employs EPS blocks for gradient replacement, and the low density of EPS, coupled with the addition of basalt fibers, significantly enhances its strength. This not only meets the requirements for replacement materials but also possesses the characteristics of being lightweight and having low density, exhibiting a certain degree of controllable deformation. By using the pre-compacted EPS layer to form a controllable deformation space, and placing it in the roadbed trench, it actively absorbs external loads. This allows for deformation absorption during road construction near rail transit, preventing pressure on the track and avoiding adverse consequences.

[0041] 2. Based on EPS blocks, this invention also features a specially designed ground beam for road sections with an elevation greater than 1.5 meters. Through the composite force transmission path of EPS blocks and ground beams, it meets the requirements of zero-load road transmission in the rail transit protection zone, reduces the center of gravity and deformation while providing road surface stability, and further reduces the load to zero by uniformly distributing pressure to reduce the pressure concentration on the ground.

[0042] 3. In the construction method of the present invention, the part of EPS block in contact with the soil is laid in steps, the top EPS block is in contact with the embankment soil, and the cast-in-place concrete on the top of the EPS block extends longitudinally to the backfill part by 1-2 meters, thereby meeting the overall stability requirements, and the surface is unified with the surrounding soil and ground, and also lays the foundation for uniform vegetation planting. Attached Figure Description

[0043] Figure 1 This is a schematic diagram showing the combination of the EPS block and the backfill portion of the present invention;

[0044] Figure 2 This is a schematic diagram of the EPS block assembly after splicing in the zero-load transmission construction method for rail transit protection zones of the present invention.

[0045] Figure 3 This is a schematic diagram of the structure in this invention that uses a double-sided claw-type connector to connect the EPS block into one piece;

[0046] Figure 4 This is a schematic diagram illustrating the use of a single-sided claw-type connector to connect EPS blocks into a single unit in this invention.

[0047] Figure 5 This is a schematic cross-sectional view of the EPS slope in the zero-load transmission construction method for roads in the rail transit protection zone of this invention. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] Example 1

[0050] This embodiment relates to a zero-load transfer construction method for roads in rail transit protection zones, which includes the following steps:

[0051] S1. Earthwork excavation: The open-cut method is adopted. The middle soil is excavated first in the horizontal direction, and then the soil on both sides is excavated. The longitudinal direction is excavated according to the zone. The excavation length of each section of the foundation pit corresponds to the zone. The vertical direction is excavated in layers from top to bottom.

[0052] S2. Excavate the existing road laterally to 0.6m, then excavate the existing road with a width of 0.5m. When overlapping, the existing road surface structure needs to be removed with a width of 0.5m. A 0.5m wide fiberglass grid is laid on the surface and bottom layers of the existing road structure, and a layer of geogrid is laid on the cement-stabilized base layer.

[0053] S3. Roadbed clearing and treatment: the thickness of the clearing and treatment should not be less than 30cm, and the original ground plant roots should be removed.

[0054] S4. Laying geofoam plastic (EPS) blocks and ground beams:

[0055] When the road design elevation minus the existing ground elevation is ≥1.5m, a structure of ground beams + EPS blocks is adopted. Three ground beams are laid inside the roadbed along the extension direction of the roadbed. Two ground beams extend along the edge of the roadbed, and the other ground beam extends along the central axis of the roadbed. A ground beam is laid transversely every 10m, so that the roadbed pit is divided into several rectangular arrays enclosed by ground beams.

[0056] When the road design elevation minus the existing ground elevation is less than 1.5m, the EPS block full-paving structure is directly adopted;

[0057] S5. At the bottom of the rectangular array, lay geotextile foam (EPS) blocks, and lay the EPS blocks layer by layer from bottom to top with staggered joints, following the principle of from low to high and from the middle to the sides. When gaps and unevenness occur between the blocks, the bottom layer is adjusted by the pad layer, and the middle layers are leveled with non-shrink cement mortar.

[0058] S6. Lay a layer of impermeable geotextile on the top layer of the EPS block, and then pour a 15cm thick C30 reinforced concrete slab on top of the EPS block.

[0059] S7. When the concrete slab reaches 70% of its strength after drying, cover the concrete slab with 80cm thick clay for equal-load preloading.

[0060] S8. Lay motor vehicle roads and sidewalks on clay;

[0061] The road structure for motor vehicles consists of: 4cm fine-grained asphalt concrete (model AC-13C) with SBS modified asphalt, 8cm coarse-grained asphalt concrete (AC-25C), 0.6cm emulsified asphalt slurry seal, 18cm cement-stabilized crushed stone (design compressive strength 4.0MPa), 18cm cement-stabilized crushed stone (design compressive strength 3.0MPa), and 15cm graded crushed stone. The total thickness of the pavement structure is 63.6cm, and the subgrade resilient modulus E0 ≥ 25MPa.

[0062] The pedestrian pavement structure consists of: 6cm permeable bricks, 3cm medium-coarse sand, 15cm C20 permeable concrete, and 10cm graded crushed stone, with a total pavement structure thickness of 34cm.

[0063] S9. For overlaying of old asphalt pavement, asphalt concrete, cement-stabilized crushed stone, graded crushed stone, and lime-soil are used as transition and leveling layers to adjust the height of the overlay.

[0064] S10. Construct slope protection using EPS blocks, laying the EPS blocks tightly against the ground beams with staggered joints. Cover the surface of the EPS blocks with a 1.5m thick layer of soil, and turf can be planted on the soil surface. Figure 5 As shown, this achieves harmony between the completed project and its surrounding environment.

[0065] Example 2

[0066] Based on Example 1, there are two cases when laying geofoam plastic (EPS) blocks:

[0067] If the road design elevation minus the existing ground elevation is ≥1.5m, a ground-supported beam structure + EPS block structure shall be adopted;

[0068] When the road design elevation minus the existing ground elevation is less than 1.5m, foamed plastic (EPS block) embankment filler roadbed shall be used.

[0069] Calculations and analysis indicate that the embankment filling using geotextile foam (EPS blocks) requires replacement with geotextile foam blocks with a unit weight of 0.3 kN / m³. Assuming the current road elevation is approximately 3.5m-4.02m and the maximum fill height is approximately 1.5m, the replacement scheme involves clearing the topsoil to a depth of 30cm and then replacing the surface with Hm geotextile foam blocks with a unit weight of 0.3 kN / m³ below the 64cm pavement structure. A 20cm layer of medium-coarse sand and a 30cm layer of gravel sand are laid at the bottom of the geotextile foam blocks, and a 0.15m thick reinforced concrete slab is laid on top of the geotextile foam blocks. It is essential to minimize the additional load on the roadbed in this section.

[0070] Calculations show that when H = 1.58m, the additional load on the roadbed is zero; after rounding, H = 1.6m. Further verification revealed that the difference between the design elevation and the ground elevation is different. Under the condition of ensuring the pavement structure, concrete slabs, and medium-coarse sand and gravel sand structure, the additional load on the roadbed can be reduced to zero by adjusting the thickness of the EPS (expanded polystyrene) material. Following the above roadbed treatment method, when the road design elevation - current ground elevation < 1.5m, using foamed plastic (EPS blocks) embankment filler for the roadbed results in a calculated foundation settlement of 0.061m upon pavement completion and a residual settlement of 0.048m within the reference period after pavement completion. This meets the allowable post-construction settlement requirements for the roadbed at the junction of the bridge and the embankment.

[0071] Roadbed buoyancy check:

[0072] Assuming the existing road elevation is approximately 3.5m, the design elevation is approximately 4.1m or higher. The depth of the high groundwater level (anti-buoyancy design water level) at the proposed site can be taken as 0.5m below the design road elevation, and the depth of the low groundwater level can be taken as 1.5m below the design road elevation. However, the road design elevation is greater than the existing road surface elevation; therefore, the anti-buoyancy design water level should be calculated based on 0.5m below the existing road surface elevation.

[0073] According to the "Technical Specification for Cast-in-Place Foamed Lightweight Soil" (CECS249:2008), the formula for calculating the buoyancy resistance of foamed lightweight soil is as follows:

[0074]

[0075] Where: Fs — anti-buoyancy coefficient;

[0076] H—Total height of foamed lightweight soil filling;

[0077] h——The total height of the foamed lightweight soil fill below the groundwater level (m);

[0078] γw — density of water, taken as 1000 kg / m3;

[0079] g—a constant, taken as 10 N / kg;

[0080] WG – Constant load on top of foamed lightweight soil fill.

[0081] The parameters to be calculated are:

[0082] The density of 12cm asphalt concrete is approximately 2400 kg / m³.

[0083] The density of 36cm water-stable material is 2300 kg / m³.

[0084] The density of 15cm graded crushed stone is approximately 1650 kg / m³.

[0085] The density of 15cm C30 reinforced concrete is approximately 2410 kg / m³.

[0086] The density of 160cm EPS foam lightweight soil is approximately 30kg / m3;

[0087] The depth of the underground groundwater level (anti-buoyancy design water level) is taken as 0.5m below the existing road elevation.

[0088]

[0089] Therefore, EPS meets the anti-buoyancy design requirements under current conditions.

[0090] Example 3

[0091] In this embodiment, the earthwork excavation is carried out in the order of segmentation-layering-symmetry-balance-time limit;

[0092] Longitudinal segmentation: The segmentation of the foundation pit excavation corresponds to the segmentation of pipeline construction. Pipeline construction is carried out in a timely manner after the last layer of soil is excavated in the foundation pit.

[0093] Vertical layering: The depth of the foundation pit excavation is divided according to the location of the support installation, and the excavation depth of each layer is about 3m;

[0094] Symmetry and balance: When excavating the foundation pit in the longitudinal direction, excavation should proceed from both ends to the middle, and the excavation of the foundation pit on both sides should be balanced to ensure that the retaining structure is evenly stressed and that the support is erected in a timely manner.

[0095] Time limit: The longitudinal excavation length of each small section of earthwork below the ring beam is 12-15m, and the excavation and support installation of the small section of earthwork must be completed within 16 hours.

[0096] In this embodiment, when the roadbed is cleared, if the roadbed is low-lying and has surface water or groundwater affecting the roadbed filling, a temporary drainage ditch is excavated to drain the base, and then a 30cm thick sand and gravel cushion layer or slag is laid on the roadbed surface.

[0097] In this embodiment, when laying EPS, a 0.2m layer of medium-coarse sand is placed at the bottom of the EPS, and the width of the medium-coarse sand exceeds the edge of the roadbed by 1m. Permeable geotextile is laid on the top and bottom of the medium-coarse sand, and the surface is kept flat and level.

[0098] Example 4

[0099] In this implementation case, modified EPS block material was used for laying. Multiple EPS blocks needed to be seamlessly spliced ​​together and laid in the trench, resulting in a shape like... Figure 2 As shown, the following section focuses on the material and quality requirements for EPS blocks:

[0100] 1. Required compressive strength: The technical specification is unconfined compressive strength. The specimen size is 50mm×50mm×50mm (allowable error ±1mm), and the loading speed is 10mm / min. When the specimen compression deformation is 5%, the average compressive strength of the EPS blocks in general areas should not be less than 110kPa, and the compressive strength of a single specimen should not be less than 80kPa. The flexural strength should not be less than 150kPa, the compression modulus should not be less than 3.5MPa, and the 7-day volumetric water absorption rate should not be greater than 1.5%. For EPS blocks in special areas such as under the bridge approach slab and sleeper beam, the compressive strength should not be less than 250kPa.

[0101] 2. Sampling and Preparation of Compressive Strength Specimens: From an EPS block, mark three cylindrical sections (100mm × 100mm × block height) from the corners and sides. Then, take one specimen from the middle and one from each of the three sections, resulting in six specimens per block. Specimens should be cut using a hot wire at least 24 hours after the EPS block is demolded to prevent excessive shrinkage, expansion, or distortion. Before the compression test, the specimens must be placed in a 60℃ oven for 24 hours to ensure they are dry.

[0102] 3. The density of the EPS block should be measured. The specimen size is 100mm×100mm×50mm. Before the density measurement, it must be placed in a 60℃ oven for 24 hours. The density of the EPS block should not be less than 20kg / m3.

[0103] 4. EPS block materials should have self-extinguishing properties when burning. The specimen size for the self-extinguishing property test is 10mm×25mm×200mm. It is lit with a match and extinguishes itself within 3 seconds after the flame source is removed. This self-extinguishing property is used as an indicator of its self-extinguishing properties when burning.

[0104] 5. EPS blocks should have consistent geometric dimensions and a flat surface. Use a measuring tape to measure at 4 points, 6 points, and 6 points on the length, width, and height respectively, and calculate the average value. The dimensions and allowable errors of standard EPS blocks are shown in the table below.

[0105] Table 1. Standard EPS Block Dimensions and Tolerancing

[0106]

[0107] 6. The maximum permissible deviation in the dimensional measurement of miscellaneous pieces cut from the standard EPS block is ±1%; the minimum usable size (length, width, height) of the block is 0.4m (unless otherwise specified).

[0108] 7. The flatness of the EPS block surface measured with a 3m straightedge should be within 5mm.

[0109] 8. During construction, all EPS blocks arriving on site must be sampled and inspected. The inspection should include checking shape, size, density, compressive strength, self-extinguishing properties, and flatness. The sampling frequency is shown in the table below.

[0110] Table 2 Sampling Frequency for EPS Block Material Quality Inspection

[0111]

[0112] Please see Figure 3 and Figure 4 As shown, to prevent misalignment between EPS blocks, claw-type connectors with a certain strength are used between the layers of the EPS block. These connectors are divided into two types: one-way claw-type connectors and double-sided claw-type connectors. Specifically, one-way claw-type connectors with a certain strength are installed on the top and side surfaces. The connectors should be rust-proofed. The blocks are fixed together using double-sided or single-sided claw-type metal connectors. Double-sided claw-type connectors are used to fix the connection between EPS blocks, while single-sided claw-type metal connectors are used to fix the connection between the outer side and top surface of the block. Figure 2 As shown, the long side of the EPS block is connected by 3 claws, the middle side by 2 claws, and the short side by 1 claw. The claws should be rust-proofed. The bottom EPS block is connected to the construction base and soil by L-shaped metal pins, and the pins are inserted into the base to a depth of not less than 50cm.

[0113] Please see Figure 1 The EPS blocks in contact with the fill are laid in steps. The top EPS cast-in-place concrete slab extends longitudinally 1-2m into the fill. The soil covering the slope should be fully compacted. The width of the soil slope protection should ensure that the net width after the slope is cut meets the design requirements.

[0114] In this embodiment, the geotextile foam EPS block is a modified EPS block, in which basalt fiber is uniformly incorporated to prevent cracking and large deformation, thereby increasing its stability.

[0115] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for zero-load transfer construction of roads in rail transit protection zones, characterized in that, The construction method includes the following steps: S1. Earthwork excavation: The open-cut method is adopted. The middle soil is excavated first in the horizontal direction, and then the soil on both sides is excavated. The longitudinal direction is excavated according to the zone. The excavation length of each section of the foundation pit corresponds to the zone. The vertical direction is excavated in layers from top to bottom. S2. Excavate the existing road laterally to 0.6m, then excavate the existing road with a width of 0.5m. When overlapping, the existing road surface structure needs to be removed with a width of 0.5m. A 0.5m wide fiberglass grid is laid on the surface and bottom layers of the existing road structure, and a layer of geogrid is laid on the cement-stabilized base layer. S3. Roadbed clearing and treatment: the thickness of the clearing and treatment should not be less than 30cm, and the original ground plant roots should be removed. S4. Laying geotextile foam blocks and ground beams: When the road design elevation minus the existing ground elevation is ≥1.5m, a structure of ground beams + EPS blocks is adopted. Three ground beams are laid inside the roadbed along the extension direction of the roadbed. Two ground beams extend along the edge of the roadbed, and the other ground beam extends along the central axis of the roadbed. A ground beam is laid transversely every 10m, so that the roadbed pit is divided into several rectangular arrays enclosed by ground beams. When the road design elevation minus the existing ground elevation is less than 1.5m, a structure of full paving with geotextile foam blocks is directly adopted. S5. Lay geotextile foam blocks at the bottom of the rectangular array, and lay the geotextile foam blocks layer by layer from bottom to top with staggered joints, following the principle of from low to high and from the middle to the sides. When gaps and unevenness occur between the blocks, the bottom layer is adjusted by the pad layer, and the middle layers are leveled with non-shrink cement mortar. S6. Lay a layer of impermeable geotextile on the top layer of the geofoam plastic block, and then pour a 15cm thick C30 reinforced concrete slab on top of the EPS block. S7. When the concrete slab reaches 70% of its strength after drying, cover the concrete slab with 80cm thick clay for equal-load preloading. S8. Lay motor vehicle roads and sidewalks on clay; The road structure for motor vehicles consists of: 4cm fine-grained asphalt concrete, 8cm coarse-grained asphalt concrete, 0.6cm emulsified asphalt slurry seal, 18cm cement-stabilized crushed stone, 18cm cement-stabilized crushed stone with a design compressive strength of 3.0MPa, 15cm graded crushed stone, a total road structure thickness of 63.6cm, and a subgrade resilient modulus E0 ≥ 25MPa. The pedestrian pavement structure consists of: 6cm permeable bricks, 3cm medium-coarse sand, 15cm C20 permeable concrete, and 10cm graded crushed stone, with a total pavement structure thickness of 34cm. S9. For overlaying of old asphalt pavement, asphalt concrete, cement-stabilized crushed stone, graded crushed stone, and lime-soil are used as transition and leveling layers to adjust the height of the overlay. S10. Construct slope protection using geotextile foam blocks. The geotextile foam blocks are laid close to the ground beam with staggered joints. Cover the surface of the geotextile foam blocks with a 1.5m thick layer of soil and plant turf on the soil surface.

2. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S1, excavation is carried out in the order of segmentation-layering-symmetry-balance-time limit; Longitudinal segmentation: The segmentation of the foundation pit excavation corresponds to the segmentation of pipeline construction. Pipeline construction is carried out in a timely manner after the last layer of soil is excavated in the foundation pit. Vertical layering: The depth of the foundation pit excavation is divided according to the location of the support installation, and the excavation depth of each layer is about 3m; Symmetry and balance: When excavating the foundation pit in the longitudinal direction, excavation should proceed from both ends to the middle, and the excavation of the foundation pit on both sides should be balanced to ensure that the retaining structure is evenly stressed and that the support is erected in a timely manner. Time limit: The longitudinal excavation length of each small section of earthwork below the ring beam is 12-15m, and the excavation and support installation of the small section of earthwork must be completed within 16 hours.

3. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S3, when the roadbed is in a low-lying area and surface water or groundwater affects the roadbed filling, the base is drained by excavating temporary drainage ditches, and then a 30cm thick layer of sand and gravel or slag is laid on the roadbed surface.

4. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S5, a 0.2m layer of medium-coarse sand is placed at the bottom of the EPS, with the width of the medium-coarse sand exceeding the edge of the roadbed by 1m. Permeable geotextile is laid on the top and bottom of the medium-coarse sand, and the surface is kept flat and level.

5. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S5, a double-sided claw-type connector is provided between the EPS blocks. The connector includes a rectangular structure equal to the bottom surface of the EPS block. The edge of the rectangular structure is provided with limiting teeth. The limiting teeth are vertically upward and vertically downward respectively, and the vertically upward teeth and the vertically downward teeth are staggered.

6. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S5, the EPS blocks in contact with the backfill are laid in a stepped manner.

7. The zero-load transfer construction method for roads in rail transit protection zones according to claim 1, characterized in that: In step S6, the top EPS cast-in-place concrete slab extends longitudinally 1-2m into the backfill area.

8. A method for zero-load transfer construction of roads in a rail transit protection zone according to claim 1, characterized in that: In step S9, when the overlay height H ≤ 12.6cm, the old pavement is milled to 12.6cm below the design elevation, and a 4cm fine-grained asphalt concrete SBS modified asphalt + 8cm coarse-grained asphalt concrete plus a 0.6cm emulsified asphalt slurry seal is laid. When 12.6cm < overlay height H ≤ 28.6cm, the overlay consists of 4cm fine-grained asphalt concrete containing SBS modified asphalt + 8-24cm coarse-grained asphalt concrete plus 0.6cm emulsified asphalt slurry seal. When the overlay height H is less than 28.6cm and less than 48.6cm, the overlay consists of 4cm fine-grained asphalt concrete with SBS modified asphalt, 8cm coarse-grained asphalt concrete, 0.6cm emulsified asphalt slurry seal, and 16-36cm cement-stabilized crushed stone. The design compressive strength of the crushed stone is 4.0MPa. When the overlay height H is less than 48.6cm and less than 63.6cm, the overlay consists of 4cm fine-grained asphalt concrete with SBS modified asphalt, 8cm coarse-grained asphalt concrete, 0.6cm emulsified asphalt slurry seal, and 36-51cm cement-stabilized crushed stone with a design compressive strength of 4.0MPa. When the overlay height H is less than 63.6cm and less than 83.6cm, the overlay consists of 4cm fine-grained asphalt concrete with SBS modified asphalt, 8cm coarse-grained asphalt concrete, 0.6cm emulsified asphalt slurry seal, 36cm cement-stabilized crushed stone, and 15-35cm graded crushed stone. When the height of the overlay is H > 83.6 cm, a 6% lime-soil transition should be used.

9. A method for zero-load transfer construction of roads in a rail transit protection zone according to claim 1, characterized in that: In step S10, the soil covering the slope should be fully compacted, and the width of the soil slope protection paving should ensure that the net width after slope cutting meets the design requirements.

10. A method for zero-load transfer construction of roads in a rail transit protection zone according to claim 1, characterized in that: The geofoam block is a modified geofoam block with basalt fiber incorporated inside.

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