Construction adit entering highway construction method

Abstract

The invention relates to the technical field of engineering construction, in particular to a construction adit entering highway construction method, and aims to solve the problem that an existing method cannot adapt to special working conditions of a construction adit. The method sequentially comprises the steps of measurement and preparation before construction, hidden slab culvert construction, roadbed excavation, roadbed filling, road shoulder surface layer ridging, side ditch construction, gravity type road shoulder wall building and road surface construction and protection. According to the method, the working conditions of the construction adit can be accurately matched, the roadbed bearing capacity and the structural stability are remarkably improved, the risks of pipeline damage, slope instability and the like are effectively avoided, key technical support is provided for efficient and safe propulsion of tunnel engineering, and later construction operation of various functional tunnels is met; and positive guiding significance is provided for the entrance road of the subsequent construction adit.

Description

Technical Field

[0001] This invention relates to the field of engineering construction technology, specifically to a construction method for a construction adit access road. Background Technology

[0002] As a core infrastructure for national economic development, highways occupy an irreplaceable position in the comprehensive transportation system due to their flexible and convenient transportation advantages. With the deepening of highway construction and the extension of high-grade highways to the mountainous areas of southwest and northwest, the scale of highway tunnel projects continues to expand, gradually upgrading from traditional two-lane tunnels to multi-lane, large-section tunnels, significantly increasing the complexity of engineering technology. As an important auxiliary structure in tunnel engineering, construction adits undertake key functions such as the transportation of construction materials in the early stage, the passage of construction personnel in the middle stage, and the inspection and maintenance in the later stage. The construction quality of the access road to the site directly determines whether the tunnel project can proceed efficiently and safely.

[0003] However, existing methods for constructing access roads to highway tunnels mostly focus on the regular traffic needs of ordinary operating tunnels, without fully considering the special working conditions and functional requirements of construction adits. For example, access roads to construction adits need to withstand the repeated loads of heavy construction machinery (such as excavators, road rollers, and concrete mixer trucks) over long periods, and must be precisely connected to the adit portal structure to avoid construction disturbances affecting the stability of the adit. However, existing methods for constructing access roads to ordinary tunnels only focus on the passage of regular vehicles, with low design standards for roadbed bearing capacity and structural durability, which easily leads to problems such as roadbed settlement and pavement cracking, resulting in construction interruptions. Construction adits are often located in mountainous areas, with complex terrain along the access roads, and there may be hidden facilities such as underground pipelines (such as gas pipelines, communication optical cables, and water pipelines) within the adjacent land area. Current methods lack a multi-dimensional, precise identification process for underground pipeline protection, making pipeline damage during construction highly likely, leading to safety accidents and project delays. Furthermore, mountainous areas experience concentrated rainfall, and existing roadbed excavation and filling techniques lack targeted drainage and slope collapse prevention measures, increasing the risk of roadbed softening due to waterlogging and slope instability. Additionally, culverts and gravity shoulder walls are core load-bearing and protective structures for access roads to construction tunnels. Current methods are inadequate in foundation treatment and backfill control for culverts (e.g., failing to differentiate backfill methods based on soil cover thickness), easily leading to culvert settlement and leakage. The requirements for foundation treatment and masonry techniques for gravity shoulder walls are vague, failing to meet the lateral earth pressure resistance requirements of shoulders in mountainous areas, easily resulting in wall tilting and cracking.

[0004] Currently, there are no publicly available technical documents and engineering practices that specifically address the construction methods for access roads to construction adits with special auxiliary functions. Existing solutions directly apply the procedures for access roads to ordinary tunnels, resulting in access roads to construction adits failing to meet engineering requirements in terms of load-bearing capacity, structural stability, and environmental adaptability. This has become a bottleneck restricting the overall progress efficiency of tunnel engineering.

[0005] In summary, given the special functional requirements of the access road to the construction adit, there is an urgent need for a specialized construction method that is highly adaptable, technologically standardized, and of controllable quality, in order to overcome the shortcomings of existing technologies and ensure the safety and efficiency of tunnel construction throughout its entire lifecycle. Summary of the Invention

[0006] In response to the special functional requirements of the access road for the construction adit, the purpose of this invention is to provide a specialized construction method that is highly adaptable, has standardized processes, and is of controllable quality, so as to overcome the shortcomings of existing technologies and ensure the safety and efficiency of tunnel engineering throughout its entire construction cycle.

[0007] This invention is achieved through the following technical solution: a construction method for a construction adit access road, comprising the following steps: (1) Surveying and construction preparation work before construction, including re-surveying and densification of traverse network and leveling network, detection of underground pipelines, re-surveying of original ground elevation, inspection of construction personnel and machinery, and technical and safety briefing; (2) Carry out the construction of the culvert, including the excavation and leveling of the foundation pit, the construction of the culvert body, the construction of the wing wall and the drop well of the side ditch, the prefabrication and installation of the cover plate, the laying of the waterproof layer and the backfilling of the culvert back; (3) Carry out roadbed excavation, adopting a method of horizontal layering, longitudinal segmentation, simultaneous excavation at both ends, and stepped excavation, and construct in layers from top to bottom and set up temporary drainage ditches; (4) Fill the excavated roadbed and simultaneously complete the filling and compaction of the shoulder foundation layer. The layer thickness should not exceed 300mm. Use a 20t vibratory roller for compaction. The bearing capacity of the lower layer needs to be tested before the upper layer is filled. (5) Topsoil is carried out on the shoulders on both sides of the highway, including topsoil excavation and layered filling and compaction, and the fill material is the subgrade material. (6) Carry out the construction of side ditches on both sides of the highway, including the excavation of side ditches and the construction of M7.5 mortar-grouted rubble masonry; (7) Construct gravity shoulder walls, including shoulder wall foundation excavation and M7.5 mortar-grouted rubble masonry construction; (8) The base course and surface course of the highway pavement shall be constructed and protected in sequence. The base course shall be made of graded crushed stone and the surface course shall be made of asphalt concrete. The protection shall include joint sealing, curb setting and traffic sign installation.

[0008] To better implement the method of the present invention, the pre-construction measurement and construction preparation work in step (1) further includes: (1.1) Before construction surveying and setting out, complete the resurvey and densification of the traverse network and leveling network, and complete the measurement and layout of the red line edge stakes, with a stake spacing of ≤50m; mark the red line edge stakes with red paint and set up protective stakes; according to the site access road layout plan, complete the land acquisition and relocation work within the access road area to ensure that there are no remaining obstacles in the land acquisition and relocation area. (1.2) Before the construction of the access road, the location and route of underground pipelines within the temporary land area shall be investigated: Based on the preliminary design data, preliminary data on underground pipelines shall be obtained by consulting local government departments and residents, and qualified geophysical exploration units shall be contacted to conduct further exploration of the pipelines using ground-penetrating radar; reflective signs with a height of 1.2m and red triangular flags with a spacing of 2m shall be set up at the location of underground pipelines for clear marking; if design changes are required, the change documents shall be submitted to the design institute for approval 7 working days before construction. (1.3) Re-measure the original ground elevation within the access road area, with a re-measurement point spacing of ≤20m. Improve the longitudinal profile design of the access road based on the original ground elevation to ensure that the longitudinal slope is ≤8%; (1.4) Before construction, the machinery and personnel entering the site shall be inspected and approved. Only after the supervisor has accepted the inspection and issued an acceptance report can the next step be carried out. (1.5) Before construction, all personnel involved in the construction shall be given technical and safety briefings to clarify their positions and responsibilities and safety production responsibilities; all machinery and equipment entering the site shall be thoroughly inspected and maintained, and inspection and maintenance signs shall be affixed after the inspection and maintenance are qualified.

[0009] To better implement the method of the present invention, the specific process of constructing the culvert in step (2) is further as follows: (2.1) Excavation and leveling of the culvert foundation pit: Before construction, the design location, direction, length, entrance and exit elevation and connection with the existing ditch or road are checked according to the design drawings and the actual site conditions. After the check is correct, water supply, power supply, road access and site leveling are achieved. The foundation pit earthwork is excavated by manual labor and excavators with bucket capacity ≤1.0m³, with an excavation slope of 1:0.5 and manual cleaning and leveling. During excavation, water collection wells with a spacing of 10m, a diameter of 80cm and a depth 1m above the bottom of the foundation pit are set up for drainage, with a drainage volume ≥5m³ / h. The foundation inspection adopts the light dynamic penetration test method, and geotechnical tests are conducted when necessary to test the foundation bearing capacity and compression modulus. When the bearing capacity of the culvert foundation is ≥200kPa, it is treated with sand and gravel with a particle size of 5-30mm and a mud content of ≤3% according to the design requirements. The replacement thickness is determined by replacing at least 30cm for every 50kPa increase to meet the foundation bearing capacity requirements. When it is located in a soft stratum with a compression modulus Es≤4Mpa, the culvert bottom foundation is treated according to the soft soil foundation treatment plan. If the geological conditions change significantly after the foundation excavation, the design unit and the supervising engineer shall be notified within 24 hours, and design changes shall be made after joint on-site investigation. (2.2) Tunnel body construction: The tunnel body is constructed with M7.5 mortar-grouted rubble masonry, and the compressive strength grade of the rubble is ≥30MPa. When constructing the mortar-grouted rubble masonry, hard, dense, durable, crack-free and weather-free stone materials are used, and the thickness of the rubble is 150-300mm. M7.5 mortar is centrally mixed at the mixing plant and transported to the site by concrete mixer trucks. The mortar is used up within 1 hour after it arrives at the site. (2.3) Construction of the sloping wall and side ditch drop shaft: The sloping wall and side ditch drop shaft are constructed with M7.5 mortar-grouted rubble masonry, with a compressive strength of ≥30MPa and a thickness of 150-300mm; M7.5 mortar is mixed by the mixing plant and transported to the site by concrete mixer truck; After the inner wall of the drop shaft is completed, it is plastered with 1:2 cement mortar, with a plastering thickness of 20mm and a flatness deviation of ≤3mm / m; (2.4) Prefabrication and installation of cover plates: Operators are familiar with the construction design drawings and construction tasks, and process the steel bars according to their type, specifications, quantity and length; steel bar raw materials and semi-finished products are classified and stored by type, specifications, quantity and length; mechanical rust removal and straightening are used before steel bar processing; The welded joints of the reinforcing bars are arranged to avoid the areas of maximum stress and to avoid bending points; the cover plates are prefabricated in the prefabrication yard, transported to the site by flatbed trucks, and installed by a 16t crane equipped with a torque limiter; the prefabricated cover plates are marked with the applicable backfill height and environmental category, and the concrete strength is tested by rebound method. They can only be hoisted, stacked and transported after reaching 85% of the design strength. During installation, the cover plate is supported at two points and tied with steel wire rope for hoisting. After the cover plate is installed, check that the four corners of the cover plate are not suspended, the center deviation of the support surface is ≤10mm, and the maximum height difference between adjacent plates is ≤10mm. (2.5) Waterproof layer laying: The waterproof layer uses 3mm thick SBS modified bitumen felt; the bitumen melting point is located downwind of the construction site (with a rainproof canopy, and the distance from the workers and material piles is ≥10m); before coating, the masonry surface is cleaned with a wire brush, kept dry, and free of mud and water; the felt is laid before the hot bitumen solidifies, and the overlap width of the felt is ≥10cm to ensure that it is bonded together without wrinkles or hollows; (2.6) Backfilling of culvert: Backfilling of culvert shall be carried out after the waterproof layer is completed and accepted. When the soil cover thickness at the top of the culvert is <0.5m, manual layering shall be used to compact the top of the culvert and the area on both sides within twice the diameter of the hole. The backfill material shall be sandy soil with mud content ≤10% or gravel with a particle size of 5mm-50mm. When the backfill thickness is greater than 0.5m, mechanical backfilling is used, with a loose layer thickness of ≤20cm, and multiple compaction passes are made using a 12t static roller. Mechanical compaction is strictly prohibited within 1m of the abutment structure, and manual compaction is carried out using a small rammer with a vibration force ≥20kN. In special cases, micro-vibration compaction can be used for areas more than 3m away from the abutment, but strong vibration compaction is strictly prohibited. If voids or pores appear during compaction, fine material with a particle size ≤5mm is added manually and compaction is repeated to ensure that the backfill layer is free of loose material and voids.

[0010] To better implement the method of the present invention, the specific process of roadbed excavation in step (3) is further as follows: For earthen road cuts, excavators with a bucket capacity of ≥1.0m³ are used for mechanical excavation, and a slope brushing layer with a thickness of not less than 20cm is reserved to prevent slope collapse and ensure slope stability. The construction principle is to move earth and rock excavation for filling. Therefore, excavation is carried out first, and the excavated soil is temporarily piled up in an area ≥5m away from the excavation surface to avoid encroaching on the slope. The road cut excavation adopts the construction method of "horizontal layering, longitudinal segmentation, simultaneous excavation at both ends, and stepped excavation". The thickness of the horizontal layer is ≤2.0m and the length of the longitudinal segment is ≤50m. The road cut excavation is carried out by excavators from top to bottom and in layers. The longitudinal drainage slope is not less than 4% to facilitate drainage. Temporary drainage ditches with a width of 30cm and a depth of 40cm are set on both sides of the roadbed of each excavation layer to promptly drain the seepage water and rainwater during the excavation process and keep the roadbed surface from being soaked by water. During the excavation process, the slope position is checked and verified once after each layer is excavated using a total station to prevent over-excavation and under-excavation of the slope. A soil layer with a thickness of not less than 20cm is reserved at the slope. The slope is trimmed by manual labor in conjunction with a small excavator with a bucket capacity of ≤0.5m³. The trimming is carried out closely following the excavation process, with an interval of ≤24 hours. Earthwork excavation shall be carried out from top to bottom in accordance with the drawings, and random or over-excavation is prohibited; regardless of the size of the project or the depth of the soil layer, blasting or excavation is strictly prohibited to avoid disturbing the surrounding rock strata of the construction tunnel and affecting the structural stability of the tunnel.

[0011] To better implement the method of the present invention, the specific process of filling the excavated roadbed in step (4) is as follows: After the roadbed filling material with a particle size ≤500mm and a mud content ≤15% is transported to the site, it is leveled using a bulldozer with a power ≥160kW and a grader, and filled in layers using an excavator with a bucket capacity ≥1.0m³. The layer thickness is no more than 300mm. After each layer is filled, the elevation is checked with a level, and the deviation is ≤5cm. During the filling process, the 300mm-500mm particle size stones are placed flat on the base to avoid the local elevation from exceeding the design value. The single excess is ≤3cm. Filling sequence: Segmented construction, segment length ≤ 100m, segment must have local roads connecting to the outside world, road bearing capacity ≥ 100kPa, to meet the needs of 50t material transport vehicles); each segment is constructed from one end to the other, the construction interval between adjacent segments is ≤ 48h, continuous construction gradually forms the conditions for traffic, ensuring the passage of material transport vehicles during the filling process; Moisture content was determined using the alcohol combustion method. The compaction was performed with the machine controlled within the optimum moisture content ±2% range, using a 20t vibratory roller. The compaction process was as follows: one pass of static compaction, two passes of weak vibration, three passes of strong vibration, and one pass of static compaction, with the speed gradually increasing from slow to fast. The initial speed was 2-3 km / h, and the subsequent speed was ≤4 km / h. The roller compacted from low to high points, from both sides to the middle on straight sections, with a compaction width overlap of 0.3m. On curved sections with a radius ≤200m, the compaction proceeded from the inside to the outside, using a longitudinal back-and-forth motion. The overlap of the roller tracks between two consecutive passes was at least 0.3m, and the longitudinal overlap between adjacent sections was at least 1m. The shoulder foundation layer is filled simultaneously with the subgrade. The shoulder foundation layer is 0.8-1.2m wide and must be filled and compacted properly. The ring cutter method is used for testing to ensure that the compaction degree is ≥96% and no dead corners are left. Before filling the upper layer of soil, a technician or tester uses a light dynamic penetrometer to test the bearing capacity of the lower layer. The bearing capacity must be confirmed to be ≥150kPa before filling can begin. It is strictly forbidden to fill multiple layers at the same time or to fill the upper layer before the lower layer is compacted. The visual standard for compaction is: the wheel track depth after strong vibration of the road roller is ≤2mm, and the settlement is ≤3mm when a 30t load transport vehicle passes over it.

[0012] To better implement the method of the present invention, the specific process of backfilling the shoulders on both sides of the highway in step (5) is as follows: (5.1) Excavation of the surface foundation of the shoulder: Excavation shall be carried out according to the inner edge line of the earthen shoulder 0.2m-0.3m away from the edge of the roadbed. The excavation size shall be 50cm wide and 30-50cm deep. Excavation shall be carried out by manual labor in conjunction with an excavator with a bucket capacity of ≤0.5m³. During excavation, the bottom elevation of the earthen shoulder shall be controlled and over-excavation shall be strictly prohibited. Loose soil on the surface and bottom of the foundation shall be removed within 24 hours after the excavation is completed. The loose soil shall be collected and transported to the designated spoil disposal site. (5.2) Shoulder surface filling: The upper layer material with a particle size ≤100mm, mud content ≤5%, and moisture content ±1% of the optimum moisture content is used for the roadbed filling and is filled in layers with a layer thickness of 15-20cm. The soil is loaded by manual labor and loaders, transported by tricycles, and compacted by small rammers with a vibration force ≥20kN. Each layer is compacted 3-4 times, and the compaction sequence is from the inside to the outside. During construction, the quality of the soil is strictly controlled, and the compaction degree of the shoulder surface layer is ≥95% to ensure that there is no looseness or voids in the shoulder surface layer.

[0013] To better implement the method of the present invention, the specific process of constructing the side ditches on both sides of the highway in step (6) is as follows: (6.1) Excavation of side ditches: Excavation shall be carried out using an excavator with a bucket capacity of ≤0.3m³ according to the center line and dimensions of the ditch; during the excavation process, a level shall be used to control the elevation of the bottom of the ditch, and over-excavation shall be strictly prohibited; loose soil on the surface and bottom of the ditch shall be removed within 12 hours after the excavation is completed, and the bottom of the ditch shall be leveled manually. (6.2) Side Ditch Construction: The side ditch is constructed using M7.5 mortar-grouted rubble masonry. Before constructing the side ditch, the roadbed excavation slope is trimmed to the design slope of 1:1.5. The M7.5 mortar is centrally mixed at the mixing plant. The rubble masonry is hard rock with a compressive strength ≥30Mpa, a thickness of 150-300mm, and no cracks or weathering. It is constructed in layers with a layer thickness of 200-300mm. The mortar is fully applied, and concave joints are used for grouting with a grouting depth ≥10mm. The masonry should be done by grouting, and the injection method is strictly prohibited. Before using the rubble stones, wet them with water and clean the surface of mud and rust. Before building the bottom of the ditch, if the base is a rock layer, clean and wet the base surface before grouting. If the base is soil, lay a 10cm thick layer of M5 cement mortar before grouting. When laying masonry, select single stone blocks of matching size with a weight of ≤50kg. Before laying each layer, first lay mortar, then lay the stone blocks and fill the joints. The exposed surface of the masonry should be grouted. Each layer of blocks should be placed firmly, with full mortar and strong adhesion. They should not be directly attached or detached. When laying the masonry, the base mortar should be fully laid. The vertical joint mortar should first be laid on the side of the already laid stones for 1 / 3. After the stones are placed, fill the gaps and tamp them down. When filling the vertical joints with C20 small stone concrete, tamp them down with a 20mm wide flat iron. Avoid vibrating the lower layer of masonry when laying the upper layer of blocks. When resuming construction after a masonry interruption, clean the surface of the already laid layer and moisten it with water.

[0014] To better implement the method of the present invention, the specific process of constructing the gravity shoulder wall in step (7) is further as follows: (7.1) Excavation of gravity shoulder wall foundation: Excavate according to the inner edge line of gravity retaining wall. The excavation size is 1.0m wide × 0.8m deep. The excavation is carried out by manual labor and an excavator with a bucket capacity of ≤0.5m³. During the excavation, control the bottom elevation of the shoulder wall and strictly prohibit over-excavation. Within 24 hours after the excavation is completed, remove the loose soil on the surface and the bottom of the foundation. Lay a 10cm thick C15 plain concrete cushion layer on the bottom of the foundation. (7.2) Gravity shoulder wall construction: The shoulder wall adopts M7.5 mortar-grouted rubble retaining wall. Before construction, the roadbed excavation slope is trimmed to the design slope of 1:1.2. M7.5 mortar is centrally mixed by the mixing plant. The rubble is hard rock with a compressive strength ≥30MPa. It is laid in layers with full mortar and smooth jointing. The masonry should be done by grouting, and the injection method is strictly prohibited. Before using the rubble stones, soak them in water to moisten them, and clean the surface mud and rust with a high-pressure water gun. Before building the shoulder wall, if the base is a rock layer, clean and moisten the base surface before grouting and masonry. If the base is soil, lay a 5cm thick layer of M5 cement mortar before grouting and masonry. When laying masonry, select matching sized stones. Before laying each layer, first lay mortar, then lay the stones and fill the joints. Point the exposed surface of the masonry. Each layer of blocks should be placed firmly, with full mortar and strong adhesion. They should not be directly attached or detached. When laying the masonry, the bottom mortar should be fully laid, and the vertical joints should be filled with C20 small stone concrete and tamped with a 20mm wide flat iron. When laying the upper layer of blocks, avoid vibrating the lower layer of blocks. When resuming construction after an interruption, the surface of the laid layer should be cleaned and moistened with water.

[0015] To better implement the method of the present invention, the specific process of constructing and protecting the surface layer of the highway pavement in step (8) is as follows: (8.1) Base course construction: The base course uses graded crushed stone with a maximum particle size ≤37.5mm, a fine particle content of less than 0.5mm ≤10%, and a plasticity index ≤6; it is paved in layers using a paver with a paving speed of 2-4m / min, with a layer thickness of 18-20cm; it is compacted using a 20t vibratory roller with a compaction degree ≥97% and a flatness deviation ≤5mm / 3m; (8.2) Surface layer construction: The surface layer is made of 5cm thick AC-13 asphalt concrete, and the asphalt is 70# road petroleum asphalt; it is laid at a uniform speed using an asphalt paver; it is compacted using a 12t double steel wheel roller, with an initial compaction temperature of 150-160℃, a secondary compaction temperature of 130-140℃, and a final compaction temperature of ≥110℃; the compaction degree is ≥96%, and the flatness deviation is ≤3mm / 3m; (8.3) Protective measures: Cut joints and inject polyurethane sealant within 24 hours after the surface layer construction is completed; set C30 concrete curb stones at the edge of the road; set one reflective traffic sign every 50m on both sides of the road, and add rubber speed bumps on sharp bends.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The construction method for access road of construction adits provided by the present invention addresses the deficiencies of the existing technology and the special working conditions of construction adits by optimizing the process logic, refining the process parameters, and strengthening quality control, thereby upgrading the construction adits access road from conventional construction to precise adaptation. (2) In the construction method of the access road for the construction adit provided by the present invention, the control standards of “layer thickness ≤ 300mm”, “20t vibratory roller compaction” and “bearing capacity of the lower layer ≥ 150kPa before the upper layer is filled” are clearly defined in the subgrade filling stage. The shoulder foundation layer is filled at the same time, so that the subgrade can withstand the heavy construction machinery load for a long time and avoid settlement and subsidence. The subgrade excavation adopts the process of “transverse layering, longitudinal segmentation and step excavation”, with a 20cm brushing layer reserved and a 30cm×40cm temporary drainage ditch set up to effectively prevent slope collapse and subgrade softening by water, and is suitable for complex terrain in mountainous areas. (3) In the construction method of the access road for the construction adit provided by the present invention, the construction of the culvert is brought forward to before the roadbed excavation. Through processes such as "drainage of the foundation pit sump well", "foundation bearing capacity ≥200kPa" and "differentiated backfilling of the culvert back", the culvert and the adit opening structure are coordinated to bear the force, avoiding structural deformation caused by later construction disturbances, and ensuring the connection stability between the adit and the access road. (4) In the construction method of the access road for the construction adit provided by the present invention, a multi-dimensional underground pipeline protection system is established by consulting the government, geophysical exploration unit, geological radar detection, reflective signs, and red triangular flags. The location and direction of pipelines within the adjacent land area are determined in advance. When design changes are required, they are submitted for approval 7 working days in advance. This completely solves the damage problem caused by the rough pipeline detection in the existing method and reduces the risk of safety accidents and construction delays. (5) In the construction method of the access road for the construction adit provided by the present invention, the side ditch is constructed using M7.5 mortar-grouted rubble masonry, and the soil base is paved with 10cm thick M5 cement mortar, which effectively improves the anti-seepage and anti-scouring capacity of the side ditch and is suitable for the concentrated rainfall drainage needs in mountainous areas; the gravity shoulder wall foundation is set with a 10cm thick C15 plain concrete cushion layer, and the wall is constructed using the mortar-sitting method, which can resist the lateral soil pressure in mountainous areas, avoid the wall from tilting and cracking, and ensure the stability of the roadside slope; (6) The construction method for access road of the construction adit provided by the present invention clarifies the thickness of the rubble of the tunnel body, the wing wall and the drop well of the side ditch and the time limit for the use of mortar. The cover plate is prefabricated with C30 concrete and can be hoisted after the strength reaches 85%. The waterproof layer is made of 3mm thick SBS modified asphalt felt. The backfill of the culvert back is strictly controlled in terms of fine particle size and compaction degree, which effectively solves the problems of culvert leakage and settlement and extends the service life. (5) In the construction method of the access road for the construction adit provided by the present invention, the surface soil of the shoulder is made of the subgrade material, with a layer thickness of 15-20cm and compacted by a rammer with a vibration force of ≥20kN to avoid the shoulder from becoming loose; the base layer of the road is made of graded crushed stone and the surface layer is made of 5cm thick AC-13 asphalt concrete, with a compaction degree of 97% and 96% respectively, and the surface layer is cut and filled with polyurethane sealant, which can resist heavy mechanical loads and temperature shrinkage stress and reduce road cracking; (6) This invention is the first to construct a dedicated technical solution for the entire process of construction preparation, core structure construction, roadbed and pavement construction and protection for the special auxiliary functions of construction adits. Among them, the processes such as "multi-dimensional pipeline detection", "roadbed layer bearing capacity detection", "differential backfilling of culvert", and "shoulder foundation-surface layer construction" are all innovative designs for the working conditions of construction adits, filling the gap in the existing technology of "no dedicated access road method for construction adits". This method can directly guide the on-site construction of access roads for construction adits in mountainous areas, ensuring that the access road meets the full-cycle functional requirements of construction adits, providing key technical support for the efficient advancement of tunnel engineering, and providing a replicable and scalable technical paradigm for subsequent similar projects. Detailed Implementation

[0017] To make the objectives, process conditions, and advantages of the present invention clearer, the present invention will be further described in detail with reference to the following embodiments. However, the embodiments of the present invention are not limited thereto. Various substitutions and modifications can be made based on common technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention, and all such substitutions and modifications should be included within the scope of the present invention. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] Example 1: This embodiment provides a specific engineering example of the construction of access roads for conventional geological formations in mountainous areas, as detailed below: 1. Project Background This embodiment focuses on the access road to a construction adit of a large-scale water conservancy project. The adit serves the functions of material transportation, personnel passage, and subsequent maintenance during construction. The access road is approximately 0.42 km long, starting from an existing road (starting elevation approximately 1951 m) and ending at the entrance of the construction adit (ending elevation approximately 1966 m). The terrain along the route has a slope of 15°-25°, and the strata are mainly cohesive soil and weathered rock, with no special soft soil strata. The road is required to withstand the passage of 20-50 t construction vehicles, and the construction period is 44 days.

[0019] 2. Construction steps (1) Surveying and construction preparation Measurement and control: Total station was used to re-measure and densify the traverse network and leveling network, with densification points spaced 30m apart. Red line edge stakes were laid out at 50m intervals, marked with red paint, and 0.8m high protective stakes were set up. The original ground elevation was re-measured, and re-measurement points were laid out at 20m intervals. The longitudinal profile design was improved, and the longitudinal slope was controlled at 5%-8% to ensure the safety of construction machinery climbing the slope.

[0020] Pipeline detection: Consult local government departments to obtain preliminary data on underground pipelines within the temporary land use area, contact qualified geophysical exploration units to conduct further exploration using ground-penetrating radar, and set up 1.2m high reflective signs at the locations of communication optical cables (buried depth 1.0-1.2m) and water pipelines (buried depth 0.8-1.0m), and hang red triangular flags at 2m intervals. No design changes are required if there are no pipeline conflicts.

[0021] Personnel and machinery preparation: The machinery entering the site includes 2 excavators with a bucket capacity of 1.0-1.2m³, 2 bulldozers, 1 20t vibratory roller, 2 loaders, and 4 20t transport vehicles. Special operation personnel shall present valid certificates for inspection and inspection, and may enter the site only after the supervisor has approved them. Technical and safety briefings shall be conducted for 30 construction personnel to clarify the responsibilities of each position, and the machinery and equipment shall be inspected and qualified labels shall be affixed.

[0022] (2) Roadbed excavation and filling: The roadbed excavation adopts the method of "transverse layering, longitudinal segmentation, simultaneous excavation at both ends, and step excavation". The thickness of the transverse layer is ≤2.0m and the length of the longitudinal segment is ≤50m. The excavator excavates from top to bottom in layers, with a longitudinal drainage slope of 5%. Temporary drainage ditches of 30cm×40cm are set on both sides of each excavation layer to drain seepage water and rainwater in time. A 20cm soil layer is reserved on the slope. The slope is trimmed by manual labor in conjunction with a small excavator with a bucket capacity of ≤0.5m³. The trimming interval is ≤24h. Blasting or digging is strictly prohibited.

[0023] Subgrade filling: The filling material is a soil-rock mixture with a particle size ≤500mm and a mud content ≤15%. Bulldozers and excavators fill in layers with a layer thickness of 250-300mm. Manual assistance is used to place 300-500mm boulders flat on the base. During compaction, the machine controls the moisture content to ±2% of the optimum (tested by alcohol combustion method). A 20t vibratory roller is used to compact the subgrade according to the process of "1 pass of static compaction → 2 passes of weak vibration → 3 passes of strong vibration → 1 pass of static compaction". The initial speed is 2-3km / h, and the speed is ≤4km / h in the later stage. The wheel track overlap is more than 0.3m and the longitudinal overlap is more than 1m. Before filling the upper layer, the bearing capacity of the lower layer is tested with a light dynamic penetrometer. Filling is allowed only if the bearing capacity is ≥150kPa. After compaction, there are no wheel tracks and the subsidence does not occur when a 30t vehicle passes through.

[0024] (3) Construction of ancillary structures Backfilling the road shoulder: Excavate a foundation 50cm wide and 30-50cm deep along the inner edge of the shoulder. Excavation is carried out manually with the help of a small excavator. The bottom elevation must be strictly controlled and over-excavation is strictly prohibited. Loose soil must be removed within 24 hours after excavation. Use the top layer material of the roadbed (particle size ≤100mm, mud content ≤5%) to fill in layers with a thickness of 15-20cm. The soil is loaded manually with the help of a loader, transported by tricycle, and compacted by a 20kN small rammer. Each layer is compacted 3-4 times, and the compaction degree is ≥95%.

[0025] Side ditch construction: Excavate a side ditch 0.5-1.0m wide and 0.5-0.6m deep along the center line of the ditch. After excavation by excavator, level it manually and remove loose soil from the bottom of the ditch. Use M7.5 mortar-grouted rubble masonry for construction. The rubble masonry should have a compressive strength ≥30MPa and a thickness of 150-300mm. Before masonry, wet the rubble with water and clean the surface soil. If the base is rock, clean and wet the rubble before laying the mortar. If it is soil, lay the mortar directly. The mortar should be full and dense. Lay the rubble in layers (layer thickness 200-300mm). The joint depth should be ≥10mm to ensure smooth drainage.

[0026] Construction of the concealed culvert: The concealed culvert is designed to be 10-12m long with a 2m diameter. After verifying the location and elevation, the foundation pit is excavated manually with the aid of an excavator. The excavation slope is 1:0.5. Water collection wells are installed at 10m intervals, with a diameter of 80cm and a depth 1m above the bottom of the pit, with a drainage capacity ≥5m³ / h. The foundation is tested using a light dynamic penetration test; if the bearing capacity is ≥200kPa, no backfilling is required, and C15 plain concrete foundation is directly poured. The culvert body and the wing wall are constructed using M7.5 mortar-grouted rubble masonry. The cover slab is prefabricated. Precast concrete (C30) on-site, and after reaching 85% strength, it is hoisted and installed using a 25t crane, with the center deviation of the support surface ≤10mm; the waterproof layer uses 3mm thick SBS modified asphalt felt, laid when the hot asphalt temperature is 160-180℃, with an overlap width ≥10cm; the backfilling of the culvert back is carried out in sections, with manual compaction in layers when the soil cover is <0.5m (compaction degree ≥96%), and mechanical compaction in layers when the soil cover is >0.5m (loose layer thickness ≤20cm), and manual compaction within 1m of the abutment backfill.

[0027] Gravity-type shoulder wall: Excavate a foundation 1.0m wide and 0.8m deep along the inner edge of the retaining wall. Excavation is carried out manually with the help of a small excavator, and the bottom elevation is strictly controlled. A 10cm thick C15 plain concrete pad is laid on the foundation, and M7.5 mortar-grouted rubble masonry is used for construction. The rubble parameters are the same as those of the side ditch. The mortar-laying method is used for construction. The masonry is laid in layers and the joints are pointed. The vertical joints are filled with C20 small stone concrete and tamped with flat iron to avoid vibration of the lower layer of blocks.

[0028] (4) Surface layer and protective construction Surface layer construction: The base course uses 20cm thick graded crushed stone with a maximum particle size ≤37.5mm, a fine particle content of less than 0.5mm ≤10%, and a plasticity index ≤6. It is laid in layers by a paver (speed 2-4m / h) and compacted by a 20t vibratory roller until the compaction degree is ≥97% and the flatness deviation is ≤5mm / 3m. The surface layer uses 20cm thick mud-bound crushed stone and is constructed according to the process of "laying crushed stone → pre-compacting → pouring slurry → laying joint filler → compacting". The water-cement ratio of the slurry is 0.8:1-1:1. Pre-compacting is done 6-10 times until the stone is no longer loose. 1-2 hours after grouting, 5-15mm joint filler is spread and compacted by a medium roller until the slurry and joint filler are bonded together.

[0029] Masonry guardrail: After the road construction is completed, the M7.5 masonry guardrail is constructed by measuring and setting out the lines, ensuring that the surface is flat and the mortar inside is full. After the masonry is built, it is plastered with M10 mortar. After the mortar has solidified, red and white warning paint is applied. Reflective signs are set at intervals of 50m, and rubber speed bumps are added to sharp bends.

[0030] (5) Construction progress control The project will proceed according to a 44-day schedule: earthwork excavation in 6 days (days 1-6), earthwork filling in 6 days (days 2-7, overlapping with excavation), side ditch in 12 days (days 8-19), culvert in 10 days (days 9-18), gravity shoulder wall in 16 days (days 20-35), pavement in 7 days (days 36-42), and guardrail in 3 days (days 43-45, with a minor adjustment of 1 day due to weather). The construction will be completed on schedule.

[0031] Example 2: This embodiment provides a specific engineering example of the construction of a construction adit access road in soft soil layers, as detailed below: 1. Project Background In this embodiment, the access road is 0.4km long, with some sections along the route consisting of soft soil (compression modulus Es=3.0-3.5MPa). The adit is responsible for transporting concrete pouring materials and must withstand repeated passage of 50t tank trucks. The construction period is 45 days, and the key issues to be addressed are the smooth flow of traffic during the soft soil foundation treatment and the construction of the culvert.

[0032] 2. Key Differentiated Construction Steps (1) Soft soil foundation treatment After the excavation of the culvert foundation pit, the foundation was tested by light dynamic penetration testing with N10=12-14 blows (bearing capacity 180-190kPa < 200kPa). According to the design, 5-30mm gravel was used for replacement, with a mud content ≤3% and a replacement thickness of 60cm (30cm replacement for every 50kPa increase, and an additional 30cm for every 20kPa increase). After layered compaction, the bearing capacity was retested and found to be ≥220kPa.

[0033] For soft soil sections of the roadbed, a composite foundation of crushed stone piles is used for treatment. The piles are 50cm in diameter, spaced 1.5m apart, and 3.0-3.5m long. After treatment, the roadbed bearing capacity is ≥180kPa, ensuring no settlement after filling.

[0034] (2) Construction of the culvert in sections The culvert is constructed in two halves, left and right. The left half is constructed first. After the excavation of the foundation pit, the pouring of the foundation, the masonry of the culvert body and the installation of the cover plate are completed, the concrete strength reaches 85% of the design strength. Then, it is backfilled and compacted in layers with sandy soil (compaction degree ≥96%) to form a temporary passageway. The right half is then constructed to ensure that the access road is not interrupted during the construction period and to meet the material transportation needs.

[0035] (3) Surface layer optimization In soft soil sections, the base course is thickened to 25cm of graded crushed stone, and the surface course consists of 20cm thick mud-bound crushed stone + 5cm thick AC-13 asphalt surface treatment. The asphalt used is 70# road petroleum asphalt. The paving temperature of the paver is ≥160℃. A 12t double-drum roller is used to compact the road surface according to the following steps: "initial compaction 150-160℃ (2 passes of static compaction) → secondary compaction 130-140℃ (3 passes of vibratory compaction) → final compaction ≥110℃ (2 passes of static compaction)". The compaction degree is ≥96%, which improves the road surface's resistance to settlement and wear.

[0036] Example 3: This embodiment provides a specific engineering example of the construction of access roads for construction adits in rainy areas, as detailed below: 1. Project Background This example is located in a rainy area with an average annual rainfall of 1200-1500mm. The access road is 0.45km long, and the terrain along the route has a slope of 20°-30°, which is prone to problems such as roadbed waterlogging and slope instability. The adit is responsible for transporting construction materials during the rainy season, so it is necessary to strengthen the waterproofing and drainage measures. The construction period is 50 days.

[0037] 2. Key Differentiated Construction Steps (1) Strengthening of drainage and waterproofing during roadbed excavation The temporary drainage ditch is deepened to 50cm for each excavation layer, and a 10cm thick gravel filter layer is laid at the bottom of the ditch to prevent siltation. Longitudinal intercepting ditches are set up on both sides of the roadbed to intercept the runoff from the hillside and prevent rainwater from eroding the roadbed. Geotextile is laid in a timely manner after the slope is trimmed and sandbags are used for protection to prevent rainwater from eroding the slope and causing it to collapse.

[0038] (2) Optimization of side ditches and drainage systems The side ditch adopts type A masonry drainage ditch (1.0m wide × 0.6m deep) with a longitudinal slope of 6% at the bottom to speed up drainage. Sedimentation wells are set every 50m in the side ditch, with a depth of 1.0m, and the silt is cleaned regularly. A rapid flow channel is set on the outside of the roadbed to divert the water from the side ditch into the natural ditch to prevent rainwater from accumulating and soaking the roadbed.

[0039] (3) Backfilling of culvert and road surface protection (corresponding documents 2.6 and 2.8) The backfill material for the culvert is permeable gravel (5-50mm in diameter), with a layer thickness of 15cm. It is compacted by a combination of manual tamping and mechanical rolling, with a compaction degree of ≥97% to prevent rainwater from seeping in and causing the backfill layer to settle. After the road surface layer is constructed, joints are cut in time (joint spacing 5m, joint width 5-8mm, joint depth 2-3cm), and polyurethane sealant is injected to prevent rainwater from seeping into the base layer and softening the roadbed through the gaps.

[0040] Although embodiments of the invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.

Claims

1. A construction adit approach highway construction method characterized by, The method comprises the following steps: (1) measurement and construction preparation before construction, the preparation work includes rechecking and encryption of traverse network and level network, underground pipeline detection, original ground elevation rechecking, construction personnel and machinery inspection and technical safety briefing; (2) carrying out the construction of the buried plate culvert, including foundation pit excavation and leveling, hole body masonry, eight-character wall and ditch drop well masonry, cover plate prefabrication and installation, waterproof layer laying and culvert backfilling; (3) carrying out roadbed excavation, adopting transverse stratification, longitudinal segmentation, two-end synchronization, ladder excavation mode, and constructing from top to bottom in layers and setting temporary drainage ditch; (4) filling the excavated roadbed, synchronously completing road shoulder foundation layer filling and compaction, the stratification thickness is not greater than 300mm, and 20t vibrating roller is adopted for rolling, and the lower bearing capacity needs to be detected before upper layer filling; (5) carrying out surface soil cultivation on the road shoulders on both sides of the road, including surface foundation excavation and stratified filling and ramming, and the filling material adopts the upper layer material of the roadbed; (6) carrying out ditch construction on both sides of the road, including ditch excavation and M7.5 mortar laid stone masonry; (7) building gravity type shoulder wall, including shoulder wall foundation excavation and M7.5 mortar laid stone masonry; (8) sequentially constructing and protecting the base layer and surface layer of the road surface, the base layer adopts graded gravel, the surface layer adopts asphalt concrete, and the protection includes joint sealing, curb stone setting and traffic sign installation.

2. The method according to claim 1, wherein, The measurement and construction preparation before construction in the step (1) comprises: (1.1) before construction measurement and line laying, completing rechecking and encryption of traverse network and level network, and completing measurement and arrangement of red line boundary stakes, the boundary stake interval is less than or equal to 50m; the red line boundary stake is marked by red paint and protection stakes are arranged, according to the approach road plan layout, completing the land acquisition and relocation work in the access road land range, and ensuring that there is no remaining obstacle in the land acquisition and relocation area; (1.2) before approach road construction, exploring the buried position and line of underground pipelines in the temporary land range: combining with the preliminary design data, further exploring the pipelines by contacting local government departments and residents to obtain preliminary data of underground pipelines, and contacting qualified pipeline units to further explore the pipelines by using the geological radar method; setting 1.2m high reflective signboards and 2m interval red triangular flags at the underground pipeline buried positions to make obvious marks; when design changes are needed, the changed data is submitted to the design institute for approval 7 working days before construction; (1.3) rechecking the original ground elevation in the approach road range, the rechecking point interval is less than or equal to 20m, and the access road longitudinal section design is improved according to the original ground elevation, and the longitudinal slope gradient is less than or equal to 8%; (1.4) before construction, the on-site machinery and personnel are inspected, and the supervision and acceptance are qualified to issue an acceptance report before entering the next procedure; (1.5) before construction, the technical briefing and safety briefing are carried out for all the personnel participating in the construction, the personnel posts and the responsibilities of all the posts are clarified, the safety production responsibilities are clarified, the on-site machinery and equipment are comprehensively maintained and maintained, and the maintenance is qualified to post maintenance marks.

3. The method according to claim 1 or 2, wherein, The specific process of carrying out the construction of the buried plate culvert in the step (2) is: (2.1) Foundation pit excavation and leveling of the culvert: Before construction, according to the design drawings combined with the actual site, review the culvert design location, direction, length, entrance and exit elevation and connection with the original ditch or road, review no error to achieve water, electricity, access and site leveling; Foundation pit earthwork is excavated by manual cooperation with bucket capacity ≤1.0m³ excavator, excavation slope 1:0.5, manual cleaning and leveling; Set up water collecting wells with a spacing of 10m, a diameter of 80cm and a depth of 1m above the foundation pit bottom for drainage when excavating, with a drainage capacity of ≥5m³ / h; The foundation inspection uses light dynamic sounding method, and if necessary, soil test is conducted to detect the foundation bearing capacity and compression modulus; When the foundation bearing capacity of the culvert is ≥200kPa, replace the sand and gravel with particle size of 5-30mm and mud content of ≤3% according to the design requirements, and replace at least 30cm for every 50kPa increase in thickness to meet the foundation bearing capacity requirements; When located in soft ground with compression modulus Es≤4Mpa, treat the culvert bottom foundation according to the soft ground treatment scheme; When the geological conditions change greatly after foundation excavation, inform the design unit and the supervising engineer within 24 hours, and jointly investigate the site to make design changes; (2.2) Culvert body masonry: The culvert body is masonry with M7.5 mortar and stone, with stone compressive strength grade ≥30MPa; When masonry with mortar and stone, use stone with hard, dense, durable, no cracks and no weathering; Stone thickness is 150-300mm; M7.5 mortar is centrally stirred by mixing station, and concrete tank truck is transported to the site; The mortar is used up within 1h after arriving at the site; (2.3) Eight-wall and ditch well masonry: Eight-wall and ditch well are masonry with M7.5 mortar and stone, with stone compressive strength ≥30MPa, thickness 150-300mm; M7.5 mortar is stirred by mixing station, and concrete tank truck is transported to the site; After the inner wall of the well is masonry, use 1:2 cement mortar to finish the surface, with a thickness of 20mm and a flatness deviation of ≤3mm / m; (2.4) Precast and installation of cover plate: The operator is familiar with the construction design drawings and construction tasks, and the steel bars are processed according to the type, specification, quantity and length; Steel bar raw materials and semi-finished products are stored according to type, specification, quantity and length; Steel bar is rusted and straightened by machine before processing; The steel bar welding head avoids the maximum stress and is dispersedly arranged, avoiding the bending part; The cover plate is uniformly prefabricated in the prefabrication yard, transported to the site by flat car, and installed by 16t hoist equipped with torque limiter; The prefabricated cover plate is marked with the applicable fill height and environmental category, and the concrete strength is detected by rebound method, which can be lifted, stacked and transported after reaching 85% of the design strength; Two-point placement is used for installation, and steel wire rope is used for hoisting and installation; After the installation of the cover plate, check that there is no overhang at the four corners of the cover plate, the center deviation of the supporting surface is ≤10mm, and the maximum height difference between adjacent plates is ≤10mm; (2.5) Waterproof layer laying: The waterproof layer uses 3mm thick SBS modified asphalt oil felt; The asphalt melting place is set in the working underground wind direction, with a rainproof canopy, and the distance from the working personnel and the stacking is ≥10m; Before coating, the surface of the masonry is cleaned with a steel wire brush, kept dry, and free of dirt and water. The oil felt is laid before the hot asphalt has solidified, with an overlap width of ≥10 cm to ensure adhesion and no wrinkles or hollows. (2.6) Backfilling of the culvert: After the waterproof layer is completed and passes the acceptance check, backfilling of the culvert is carried out. When the thickness of the overburden is <0.5 m, the top of the culvert and the area within two times the diameter on both sides are artificially layered and compacted. The backfilling material is sandy soil with a silt content of ≤10% or gravel with a particle size of 5-50 mm. When the overburden thickness is >0.5 m, mechanical backfilling is used, with a layered thickness of ≤20 cm. A 12-ton static pressure roller is used for multiple compactions. Within a 1-m range from the abutment structure, mechanical rolling is strictly prohibited. A small-sized tamper with an excitation force of ≥20 kN is used for manual compaction. In special cases, micro-vibration rolling can be used beyond 3 m from the abutment. Strong vibration rolling is strictly prohibited. When voids or pores appear during rolling, fine material with a particle size of ≤5 mm is manually added for re-rolling to ensure that the backfill layer is not loose or voided.

4. The method according to claim 1 or 2, wherein, The specific process of roadbed excavation in step (3) is as follows: For earthwork cutting, a excavator with a bucket capacity of ≥1.0 m³ is used for mechanical excavation. A brush layer with a thickness of not less than 20 cm is reserved to prevent slope collapse and ensure slope stability. The construction principle is to remove earthwork for filling, so excavation is carried out first. The excavated soil is temporarily stored in an area ≥5 m away from the excavation face to avoid occupying the slope. The cutting is constructed in a way of "horizontal layering, vertical sectioning, both ends synchronously, and stepwise excavation". The horizontal layering thickness is ≤2.0 m, and the vertical sectioning length is ≤50 m. The cutting is excavated from top to bottom in layers using a excavator. The longitudinal drainage slope is not less than 4% to facilitate drainage. Temporary drainage ditches with a width of 30 cm and a depth of 40 cm are set on both sides of the roadbed at each excavation layer to drain the seepage and rainwater during excavation from the excavation face, keeping the roadbed surface from being soaked in water. During excavation, the position of the slope is checked once for each layer of excavation using a total station instrument to prevent over-excavation and under-excavation of the slope. The reserved thickness of the slope is not less than 20 cm of soil layer. Small excavators with a bucket capacity of ≤0.5 m³ are used for slope trimming. The trimming is closely followed by the excavation process, with an interval of ≤24 h. Earthwork excavation is carried out from top to bottom according to the requirements of the drawings. No random excavation or over-excavation is allowed. Regardless of the amount of work or the depth of the soil layer, blasting or hole digging is strictly prohibited to avoid disturbing the surrounding rock of the construction tunnel and affecting the stability of the tunnel structure.

5. The method according to claim 4, wherein, The specific process of filling the excavated roadbed in step (4) is as follows: After the roadbed filling material with a particle size of ≤500 mm and a silt content of ≤15% is transported to the site, a bulldozer with a power of ≥160 kW and a grader are used for leveling, and a excavator with a bucket capacity of ≥1.0 m³ is used for layer-by-layer filling. The layer thickness is not more than 300 m. After each layer is filled, the elevation is detected using a level gauge with a deviation of ≤5 cm. During the filling process, manually assisted block stones with a particle size of 300-500 mm are placed on the base to avoid local elevation exceeding the design value by ≤3 cm. Filling sequence: segmented construction, segment length ≤100m, segment must have a place road connected with the outside world, road bearing capacity ≥100kPa, meet heavy 50t material transport vehicle traffic); each segment from one end to the other end construction, adjacent segment construction interval time ≤48h, continuous construction piece by piece form traffic conditions, guarantee the filling process material transport vehicle traffic; Adopt alcohol combustion method to detect moisture content, control compaction time in the best moisture content ±2% period, adopt 20t vibrating roller to roll; Rolling process is: first static pressure 1, weak vibration 2, strong vibration 3, static pressure 1, speed from slow to fast, initial speed 2km / h-3km / h, later speed ≤4km / h; The roller is arranged from low to high, straight line from both sides to the middle, rolling width overlap 0.3m, radius ≤200m curve, from inside to outside, longitudinal advance and retreat type; The front and rear two tracks of vibrating roller overlap more than 0.3m, the front and rear two sections overlap more than 1m longitudinally; Shoulder base layer and roadbed synchronous filling, shoulder base layer width 0.8-1.2m, must be filled and compacted in place, adopt ring knife method to detect, ensure the compaction degree ≥96%, no dead angle; Before upper layer soil filling, the technician or tester uses light dynamic sounding instrument to detect the bearing capacity of the lower layer, confirms that the bearing capacity is ≥150kPa, and only after passing the test can the filling be carried out, and it is strictly forbidden to fill multiple layers together or fill the upper layer before the lower layer is compacted; The direct standard for compaction is: the wheel track depth after strong vibration of the roller is ≤2mm, and the settlement amount is ≤3mm when the 30t heavy transport vehicle passes through.

6. The method according to claim 1 or 2, wherein, The specific process of step (5) for cultivating the road shoulders on both sides of the highway is: (5.1) Shoulder surface layer excavation: excavate according to the inner edge line of the cultivated shoulder 0.2-0.3m from the roadbed edge, the excavation size is 50cm wide × 30-50cm deep, excavate with manual cooperation of excavator with bucket capacity ≤0.5m³; Control the bottom elevation of the cultivated shoulder during excavation, and strictly prohibit overexcavation; Remove the loose and floating soil on the surface and the bottom within 24 hours after excavation is completed, and the floating soil is transported to the designated spoil site; (5.2) Shoulder surface layer filling: use the upper layer material with particle size ≤100mm, silt content ≤5%, and moisture content of best moisture content ±1% for filling, with layer thickness of 15-20cm; Use manual cooperation with loader to load soil, three-wheeled vehicle transportation, and small-sized tamping machinery with vibration force ≥20kN for tamping, tamping 3-4 times per layer, and tamping sequence from inside to outside; During construction, strictly control the quality of the soil, and the compaction degree of the shoulder surface layer is ≥95% for layered filling, ensuring that the shoulder surface layer is free of loose and hollow.

7. The method according to claim 1 or 2, wherein, The specific process of step (6) for constructing the side ditch on both sides of the highway is: (6.1) Ditch excavation: excavate according to the water ditch center line and ditch size, using excavator with bucket capacity ≤0.3m³; Control the ditch bottom elevation with a level during excavation, and strictly prohibit overexcavation; Remove the loose and floating soil on the surface and the bottom within 12 hours after excavation is completed, and the bottom is leveled by manual work; (6.2) Ditch masonry: ditch is masonry with M7.5 mortar and piece stone, before construction of ditch, the slope of roadbed excavation is trimmed to the design slope 1:1.5; M7.5 mortar is centrally stirred by mixing station, piece stone is hard rock with compressive strength ≥30MPa, thickness 150-300mm, without crack and weathering, and is layered masonry with thickness 200-300mm, mortar is full, concave joint is adopted with joint depth ≥10mm; Masonry is adopted with mortar method, grouting method is strictly prohibited; piece stone is wetted with water before use, surface soil and water rust is cleaned; before masonry of ditch bottom, if base is rock layer, surface of base is cleaned and wetted before masonry; if base is soil, 10cm-thick M5 cement mortar is laid before masonry; Piece stone with matching size and weight ≤50kg is selected for masonry, mortar is laid before each layer of masonry, then piece stone is masonry and joint is filled; exposed surface of masonry is jointed, each layer of piece stone is stably placed, mortar is full and firmly bonded, and piece stone is not directly attached or spaced apart; Full mortar is laid for masonry, mortar for vertical joint is laid on 1 / 3 of side surface of masonry piece, then masonry piece is placed and filled and tamped; C20 small stone concrete is used for filling vertical joint and tamped with flat iron with width 20mm; upper masonry piece is masonry without vibration of lower masonry piece, surface of masonry layer is cleaned and wetted when construction is resumed after interruption.

8. The method according to claim 1 or 2, wherein, The specific process of constructing gravity type shoulder wall in step (7) is: (7.1) Excavation of foundation of gravity type shoulder wall: excavation is performed according to inner line of gravity type retaining wall, and the size of excavation is 1.0m in width and 0.8m in depth, and excavation is performed by manual work with excavator with bucket capacity ≤0.5m³; during excavation, the bottom elevation of shoulder wall is controlled, and over-excavation is strictly prohibited; within 24h after completion of excavation, surface and loose soil at the bottom of foundation are removed, and 10cm-thick C15 plain concrete cushion is laid on the bottom surface of foundation; (7.2) Masonry of gravity type shoulder wall: M7.5 mortar masonry piece wall is adopted for shoulder wall, and the slope of roadbed excavation is trimmed to the design slope 1:1.2 before construction; M7.5 mortar is centrally stirred by mixing station, and piece stone is hard rock with compressive strength ≥30MPa, and is layered masonry with full mortar and smooth joint; Masonry is adopted with mortar method, grouting method is strictly prohibited; piece stone is wetted with water before use, surface soil and water rust is cleaned; before masonry of shoulder wall, if base is rock layer, surface of base is cleaned and wetted before masonry; if base is soil, 5cm-thick M5 cement mortar is laid before masonry; Piece stone with matching size is selected for masonry, mortar is laid before each layer of masonry, then piece stone is masonry and joint is filled; exposed surface of masonry is jointed, each layer of piece stone is stably placed, mortar is full and firmly bonded, and piece stone is not directly attached or spaced apart; Full mortar is laid for masonry, C20 small stone concrete is used for filling vertical joint and tamped with flat iron with width 20mm; upper masonry piece is masonry without vibration of lower masonry piece, surface of masonry layer is cleaned and wetted when construction is resumed after interruption.

9. The method according to claim 1 or 2, wherein, The specific process of constructing and protecting surface layer of highway pavement in step (8) is: (8.1) Base construction: the base uses graded gravel, the maximum particle size is ≤37.5mm, the content of fine particles less than 0.5mm is ≤10%, the plasticity index is ≤6; the paving machine is used to layer paving at the paving speed of 2-4m / min, the layer thickness is 18-20cm; the 20t vibrating roller is used for rolling, the compaction degree is ≥97%, the flatness deviation is ≤5mm / 3m; (8.2) Surface layer construction: the surface layer uses 5cm thick AC-13 asphalt concrete, the asphalt uses 70# road petroleum asphalt; the asphalt paver is used for uniform speed paving; the 12t double steel wheel roller is used for rolling, the initial rolling temperature is 150-160℃, the re-rolling temperature is 130-140℃, the final rolling temperature is ≥110℃; the compaction degree is ≥96%, the flatness deviation is ≤3mm / 3m; (8.3) Protection measures: the surface layer is cut and jointed within 24h after the surface layer construction is completed, the polyurethane sealant is injected; the C30 concrete curb is arranged at the road edge; one reflective traffic sign is arranged every 50m on both sides of the road, and the rubber speed reduction belt is additionally arranged at the sharp curve section.