Urban tunnel construction technology in ecological sensitive area

Abstract

The invention discloses an ecological sensitive area urban tunnel construction technology. The technology comprises the following steps that 1, traffic guidance and modification are conducted; step, greening relocation and modification; thirdly, construction preparation is conducted; fourthly, enclosure construction is conducted; 5, constructing a main body structure; sixthly, waterproof construction is conducted; 7, accessory structure construction; 8, assembling an achievement report; according to the method, greening facilities are migrated or changed, so that damage to the environment in the tunnel construction process is avoided, and the normal ecological environment is prevented from being influenced; various accessory structures are mounted in the tunnel, so that accidents in the tunnel can be found in time, and normal passage of the tunnel is prevented from being influenced; the waterproof performance of the tunnel is effectively improved through concrete structure self-waterproofing, waterproof roll construction, construction joint waterproofing, deformation joint waterproofing, pile head waterproofing and the like completed in the tunnel construction process, the tunnel is effectively prevented from cracking or rainwater is effectively prevented from permeating into the tunnel in severe weather, and the safety of the tunnel is improved.

Description

[0001] This application claims priority to Chinese patent application filed on January 22, 2025, with application number 202510102630.8, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of tunnel construction, in particular to a construction process for urban tunnels in ecologically sensitive areas. Background Art

[0003] In recent years, with the progress of urban construction and the development of urbanization, a large number of migrant population have moved from rural areas to cities, and the number and scale of cities have undergone many changes. The increasingly large urban population and the constant pursuit of quality of life have brought about increasing urban traffic pressure year by year. The existing transportation system can no longer meet the requirements of urban travel. The construction of urban underground tunnels will greatly alleviate urban traffic pressure, facilitate travel, and accelerate personnel flow and urban development. The existing urban tunnel construction technology basically meets the needs, but there are still certain shortcomings. The existing tunnel construction technology may cause damage to the nearby environment during the construction process, and have a greater impact on the urban ecological environment. Summary of the Invention

[0004] The purpose of the present invention is to provide a construction process for urban tunnels in ecologically sensitive areas to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a construction process for an urban tunnel in an ecologically sensitive area, comprising the following steps: step 1, traffic diversion; step 2, greening relocation; step 3, construction preparation; step 4, enclosure construction; step 5, main structure construction; step 6, waterproofing construction; step 7, auxiliary structure construction; step 8, compilation of achievement report;

[0006] In step 1 above, a reasonable traffic organization plan will be formulated in conjunction with traffic police based on actual traffic conditions. Traffic diversion plans will be prepared based on the starting and destination points of vehicles. Multiple carriers will be used to form high-density, three-dimensional, real-time, rolling guidance, improve information symmetry, and induce balanced traffic flow distribution. Traffic coordinators will be arranged at important intersections affected by construction.

[0007] In the above step 2, the greening facilities within the construction area are relocated or modified to avoid affecting the normal ecological balance;

[0008] In the above step 3, preparatory work before construction is done to create conditions for the formal construction of the tunnel project;

[0009] In the above step 4, the construction of the retaining structure is completed by bored cast-in-place piles and bored interlocking piles;

[0010] In the above step 5, after the enclosure structure is completed, the main structure of the tunnel is constructed;

[0011] In the above step 6, waterproofing construction is performed on the tunnel structure;

[0012] In the above step 7, after the main structure of the tunnel is completed, the auxiliary structure is installed;

[0013] In the above step eight, the tunnel construction record reports are summarized, and the construction process of each segment structure is summarized and analyzed to write a results report to provide support for the subsequent optimization of the construction process.

[0014] Optionally, in step three, the construction preparation is specifically as follows: first, set up temporary facilities, install fences and build temporary construction access roads; second, obtain construction machinery and testing equipment, review control point data and establish an on-site construction control network, and check underground pipelines; third, establish a conductor network for this section; fourth, complete the construction of the large temporary project; fifth, according to the preset traffic relief plan, carry out the first phase of traffic improvement construction to ensure the accessibility of the road; sixth, after the first phase of traffic improvement is completed, install tunnel engineering construction fences, level the construction site, and make the working surface meet the conditions for construction operations.

[0015] Optionally, in step four, the sequence of the single pile construction process is: site leveling, measuring and placing pile positions, constructing concrete guide walls, positioning the pile driver, positioning the casing drill, hoisting and installing the first section of casing, measuring and controlling verticality, pressing in the first section of casing, checking verticality, taking soil with a grab bucket, pressing in the casing, measuring the hole depth, removing loose soil, inspection, hoisting the steel cage of pile B, installing the guide tube, pouring concrete, pulling out the tubes one by one, measuring the concrete elevation, and moving the pile driver.

[0016] Optionally, in the step four, the specific construction process is as follows: the first step: guide wall construction, a reinforced concrete guide wall is constructed on the top of the pile, and the guide wall is placed 100 mm outward according to the coordinates provided in the design drawings to offset the reduction in the clearance of the foundation pit structure caused by the inward displacement and deformation of the interlocking pile under the action of the external soil pressure during foundation pit excavation, and the center line coordinates of the pile row are calculated. The guide wall is 3.5 meters wide and 35 centimeters thick, and the material is C25 concrete; the second step: the drilling rig is in place, and the center position of the pile is determined as the control point for positioning the drilling rig; the third step: soil is taken to form a hole. After the pile foundation is in place, a soil layer with a depth of 2.5 to 3 meters is taken and obstacles are cleared. Then a steel casing is sunk into the fully weathered rock layer using a puller. The steel casing is 10 mm thick and the verticality is tested, such as the verticality. If the target verticality is not reached, corrections will be made. If the verticality reaches the target verticality, soil will be taken downwards until the designed hole bottom elevation is reached; the fourth step: production and installation of the steel cage. The steel cage is hoisted by a crane. The design elevation is determined by the casing top elevation. The error during installation is ±10 mm. When the steel cage is lowered, it is gradually sunk by positive or reverse rotation to prevent collision. It is fixed after being placed at the designed elevation; the fifth step: concrete pouring. The concrete is reinforced piles and underwater C35 concrete is used; super slow-setting C35 concrete is used for plain piles; the sixth step: pulling out the pipe to form the pile. The verticality of the pile is monitored and inspected during the drilling process; the seventh step: ground monitoring. During the casing pressing process, a hammer ball is used to detect the verticality of the casing from two mutually perpendicular directions, and corrections are made when deviations are found.

[0017] Optionally, in step 4, the specific process of concrete pouring construction is as follows: the concrete pouring conduit is connected with a screw thread and a rubber sealing ring, and the inner diameter is 25 cm; the conduit is slowly lowered into the hole by a crane, and the bottom of the conduit is 30 cm to 50 cm higher than the bottom of the hole. The upper end of the conduit is connected to a concrete funnel, and concrete flows into the funnel through a chute. When conditions are difficult, a crane can be used to lift the concrete into the funnel through a hopper. After more than 2 cubic meters of concrete is placed in the funnel, the bottom cover of the funnel is pulled out, and concrete is poured into the conduit, and the concrete is continuously poured. During the pouring process, the water level in the hole is detected, the actual height of the concrete surface is measured, and the buried depth of the conduit is calculated, so that the bottom end of the conduit is buried below the concrete surface. 2 meters to 6 meters, after the concrete pouring is completed, the casing and conduit are gradually removed; according to the buried depth of the conduit, 1 to 2 sections of the conduit are removed each time, and the conduit is rinsed clean after removal for next use; when the casing is lifted, slowly pull it up and shake it left and right to allow concrete to flow into the space occupied by the casing, and at the same time pay attention to whether the steel cage floats up. The casing is buried at a depth of about 2 meters, and the concrete is poured to 0.5 meters above the pile top elevation. This part of the concrete is chiseled off before the construction of the crown beam. The retarding time of the pile concrete is determined according to the pile-building time of the single pile. The pile-building time of the single pile is directly related to the geological conditions, pile length, pile diameter and drilling rig capacity. The calculation formula for the retarding time of the pile concrete is:

[0018] T = 3t + K;

[0019] Where T is the retarding time of the plain pile concrete, K is the reserve time, which is generally taken as 1.5t, and t is the time it takes to form one of the piles, A and B.

[0020] Optionally, in step five, the specific process of main structure construction is as follows: first, after the foundation pit is excavated to the design elevation, the pit is inspected and the structure is measured and laid out; the formwork support system of the side walls and top plates is designed and calculated, and a tunnel formwork support plan is prepared and then implemented, and material feeding is arranged according to the construction progress; second, the plain cushion layer is constructed, and the cushion layer concrete is C20, 20 cm thick. The cushion layer construction is carried out closely following the excavation surface to prevent the base from being exposed for too long, eliminate water accumulation in the foundation pit, remove the loose soil in the foundation pit, clean and level the silt and debris on the top of the pull-out piles, and after the foundation pit is cleaned, use a tamping machine to tamp the base. Carry out comprehensive compaction and measure the bearing capacity of the foundation. When the cushion concrete is spread, the surface elevation is controlled according to the pre-buried horizontal piles. The concrete is vibrated with a flat vibrator. After the initial setting and before the final setting of the cushion concrete, the surface layer of the cushion concrete is twice smoothed and cured to prevent loosening, sanding and peeling. The cushion pouring thickness is controlled according to the pre-buried elevation control piles, and the surface is closed and cured to ensure that there are no honeycombs, rough surfaces and cracks on the cushion surface. Third: The bracket used for the main structure frame concrete construction is a disc-type full-floor bracket. Each disc-type upright in the disc-type full-floor bracket can withstand 8 to 9 tons of vertical load, the vertical load includes the side pressure of the side wall concrete, the weight of the top slab concrete, the weight of the formwork, the construction load and the wind force acting on the formwork support. In the said disc-type full-floor support, the horizontal rods are spaced 60 cm in the longitudinal direction, the disc-type vertical rods are spaced 90 cm in the transverse direction, and the disc-type vertical rods adjacent to the chamfers are spaced 60 cm in the transverse direction to strengthen the rigidity of the longitudinal and transverse beams of the top slab and the side wall transverse belts and vertical belts; Fourth: formwork, the outer formwork of the concrete project uses the side wall of the enclosure structure. Before the construction of the side wall, the wall surface of the enclosure structure should be trimmed and leveled first; the formwork consists of the bottom formwork, The side wall and top formwork are composed of three parts and are assembled on site. The formwork adopts steel formwork (large steel formwork) and is processed into a frame with angle steel and channel steel. The bakelite board is connected to the frame as a whole and processed into blocks according to the design drawings and assembled on site; fifth: reinforcement. After the base waterproof coating is applied, the bottom plate reinforcement is tied. The side wall and top plate reinforcement are tied after the bottom plate concrete construction is completed and the inner formwork and bottom formwork are installed, and joint reinforcement is reserved; sixth: concrete pouring. Commercial concrete is used, which is transported by concrete tank trucks and pumped into the mold by concrete pump trucks. Slag cement is used to reduce the hydration heat generated by the concrete during solidification.

[0021] Optionally, in step six, the specific process of waterproofing construction is as follows: step one: self-waterproofing of concrete structure. The self-waterproofing design of concrete structure determines the material according to the environmental conditions to meet the requirements of concrete's own impermeability, durability and crack resistance; waterproof concrete is prepared by adjusting the mix ratio, adding admixtures and admixtures, and the structural concrete impermeability grade, structural concrete water-cement ratio and minimum amount of cementitious materials are determined according to the strength of the concrete structure and the structural burial depth; the top plate concrete and the side wall concrete cast together with the top plate concrete are added with fly ash and slag to reduce shrinkage due to drying and temperature difference shrinkage; step two: waterproof membrane construction, the side walls and the bottom plate are Use 1.5mm thick pre-laid polymer waterproof membrane. When the pre-laid waterproof membrane is laid by the outer-proof inner-sticking method, the bottom plate is laid by the empty laying method, and the facade is laid by the mechanical fixing method. The membranes are tightly pasted together. The top plate concrete adopts a flexible waterproof layer, and the flexible waterproof layer adopts a coating waterproof layer. The flexible waterproof layer is set on the water-facing side of the structure. The waterproof coating type of the coating waterproof layer is determined according to the engineering environment, climatic conditions, construction methods, structural construction forms, and engineering waterproof grade requirements. At the same time, the wet base layer uses a single-component polyurethane waterproof coating or polymer cement waterproof coating that has adhesion to the wet base surface. The selected coating type has good water resistance and durability. The waterproof coating thickness is 2.0 mm, and the protective layer of the coating waterproof layer is determined according to the specific parts of the structure; the internal and external corners of the structural concrete where the waterproof layer is applied are made into arcs or 45° angles, and the size of the internal and external corners is determined according to the type and thickness of the waterproof material; reinforcement layers are added at the corners and internal and external corners, and the width of the reinforcement layer is greater than or equal to 500 mm; the third step: waterproofing the construction joints, the spacing of the construction joints is less than or equal to 16 meters, and the horizontal construction joints of the wall are in the area except for the maximum shear force or the junction of the bottom plate and the side wall. When there are reserved holes in the wall, the construction joints are greater than or equal to 300 mm from the edge of the hole; the fourth step: Waterproofing of expansion joints. The waterproofing measures taken at the expansion joints can meet the sealing and waterproofing requirements during the differential settlement and longitudinal expansion of the structures at both ends of the joints. Multiple defenses are carried out by adopting the methods of embedded waterstop, external waterstop, internal removable waterstop and sealant caulking. The embedded waterstop, external waterstop and internal removable waterstop adopt medium-hole type or Ω-type waterstop; Step 5: Pile head waterproofing. The waterproof material selected for the pile head has the ability to increase the density of concrete, adhesion with the pile head concrete and steel bars, water resistance and moisture curing properties. If a flexible waterproof layer is laid on the base plate, the rigid waterproof layer of the pile head and the flexible waterproof layer of the base plate form a continuous and closed waterproof system.

[0022] Optionally, in step seven, the ancillary structures include electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering, and the electrical installation includes: tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection grounding and others, pump room and ancillary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcasting system, emergency telephone system, wireless communication system and UPS uninterruptible power supply system.

[0023] Optionally, in step seven, the specific process of installing the ventilation equipment includes the installation and commissioning of the fan and control box in the tunnel, and the installation process of the ventilation control box includes the fan unpacking inspection, pre-embedding of fan parts, welding of connection accessories and tensile strength test, fan installation, cable laying, control box installation and cable connection, and experimental acceptance;

[0024] In step seven, the fire protection project includes fire water sources, fire protection facilities, tunnel fire water supply system, fire hydrant water supply system, water film-forming foam fire protection system, fire extinguishers and ground fire protection.

[0025] In another aspect, a construction process for an urban tunnel in an ecologically sensitive area is provided, comprising: step 1, traffic diversion; step 2, greening relocation; step 3, construction preparation; step 4, enclosure construction; step 5, main structure construction; step 6, waterproofing construction; step 7, auxiliary structure construction; and step 8, compilation of a results report.

[0026] In the step 1, a traffic diversion plan is determined according to the starting point and destination of the vehicle;

[0027] In the second step, the greening facilities within the construction area are relocated or modified;

[0028] In step three, construction preparation includes: first, setting up temporary facilities, installing fences, and building temporary construction access roads; second, obtaining construction machinery and testing equipment, reviewing control point data, establishing an on-site construction control network, and checking underground pipelines; third, establishing a conductor network for this section; fourth, completing the construction of the major temporary project; fifth, carrying out the first phase of traffic improvement construction to ensure accessibility according to the preset traffic relief plan; sixth, after the completion of the first phase of traffic improvement, installing tunnel construction fences, leveling the construction site, and making the working surface ready for construction operations;

[0029] In the fourth step, the construction of the retaining structure is completed by bored cast-in-place piles and bored interlocking piles;

[0030] In the step 5, after the enclosure structure is completed, the main structure of the tunnel is constructed;

[0031] In the step 6, waterproofing is performed on the tunnel structure;

[0032] In step seven, after the construction of the main tunnel structure is completed, the installation and construction of the auxiliary structures are carried out. The auxiliary structures include electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering. The electrical installation includes: tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection and grounding and others, pump room and auxiliary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcasting system, emergency telephone system, wireless communication system and UPS uninterruptible power supply system.

[0033] Compared with the existing technology, the beneficial effects of the present invention are: this urban tunnel construction process in ecologically sensitive areas avoids damage to the environment during tunnel construction and affects the normal ecological environment by relocating or modifying greening facilities; through the electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering and other auxiliary structures carried out in the tunnel, real-time monitoring of the tunnel is achieved, and accidents can be discovered in time to avoid affecting the normal passage of the tunnel; the concrete structure self-waterproofing, waterproof membrane construction, construction joint waterproofing, expansion joint waterproofing and pile head waterproofing completed during the tunnel construction process effectively improve the waterproof performance of the tunnel, effectively prevent the tunnel from cracking or rainwater from penetrating into the tunnel in the face of severe weather, and improve the safety of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The applicant found that the existing technology for urban tunnel construction in ecologically sensitive areas has at least the following problems: First, the existing tunnel construction technology may cause damage to the surrounding environment during the construction process, causing a significant impact on the urban ecological environment; second, the existing tunnel construction technology has few installation requirements for tunnel ancillary equipment during the construction process, and accidents cannot be discovered in time, which may affect the normal passage of the tunnel; third, the existing construction technology may cause cracks in the concrete or rainwater infiltration during the construction process due to special weather conditions, affecting the safety of the tunnel; therefore, it is very necessary to design a construction technology for urban tunnels in ecologically sensitive areas.

[0037] The embodiments of the present application provide a construction process (or construction method) for urban tunnels in ecologically sensitive areas, which can solve some of the problems existing in the above-mentioned prior art.

[0038] Please see the attached Figure 1 The present invention provides an embodiment of a construction process for an urban tunnel in an ecologically sensitive area, comprising the following steps: Step 1, traffic diversion; Step 2, greening relocation; Step 3, construction preparation; Step 4, enclosure construction; Step 5, main structure construction; Step 6, waterproofing construction; Step 7, auxiliary structure construction; Step 8, achievement report compilation;

[0039] In step 1 above, a reasonable traffic organization plan will be formulated in conjunction with traffic police based on actual traffic conditions. Traffic diversion plans will be prepared based on the starting and destination points of vehicles. Multiple carriers will be used to form high-density, three-dimensional, real-time, rolling guidance, improve information symmetry, and induce balanced traffic flow distribution. Traffic coordinators will be arranged at important intersections affected by construction.

[0040] In the above step 2, the greening facilities within the construction area are relocated or modified to avoid affecting the normal ecological balance;

[0041] Similarly, the present application also provides a construction process for an urban tunnel in an ecologically sensitive area, comprising: step 1, traffic diversion; step 2, greening relocation; step 3, construction preparation; step 4, enclosure construction; step 5, main structure construction; step 6, waterproofing construction; step 7, auxiliary structure construction; step 8, compilation of achievement report;

[0042] In step 1, a traffic diversion plan is determined based on the starting point and destination of the vehicle;

[0043] In step 2, the greening facilities within the construction area are relocated or modified;

[0044] In step three, construction preparation includes: first, setting up temporary facilities, installing fences, and building temporary construction access roads; second, obtaining construction machinery and testing equipment, reviewing control point data, establishing an on-site construction control network, and checking underground pipelines; third, establishing a conductor network for this section; fourth, completing the construction of the major temporary project; fifth, carrying out the first phase of traffic improvement construction to ensure accessibility according to the prepared traffic diversion plan; and sixth, installing tunnel construction fences after the first phase of traffic improvement is completed, leveling the construction site, and ensuring that the working surface is ready for construction operations.

[0045] In step 4, the construction of the retaining structure is completed by bored cast-in-place piles and bored interlocking piles;

[0046] In step 5, after the enclosure structure is completed, the main structure of the tunnel will be constructed;

[0047] In step six, waterproofing of the tunnel structure is carried out;

[0048] In step seven, after the construction of the main tunnel structure is completed, the installation and construction of the auxiliary structures will be carried out. The auxiliary structures include electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering. The electrical installation includes: tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection and grounding and others, pump room and auxiliary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcasting system, emergency telephone system, wireless communication system and UPS uninterruptible power supply system.

[0049] Among them, in the above step three, preparatory work before construction is done to create conditions for the formal construction of the tunnel project; the construction preparation is specifically as follows: first: preparation for construction site entry, mainly setting up a project management department, setting up temporary facilities, installing fences, and building temporary construction access roads; second: organizing the entry of construction machinery and testing equipment, reviewing control point data, establishing an on-site construction control network, familiarizing yourself with the construction drawings, organizing drawing reviews, and checking underground pipelines; third: establishing a conductor network for this section; fourth: urging construction machinery and personnel to enter the site according to the requirements of the construction working surface, and completing the construction of the temporary project as soon as possible; fifth: according to the preset traffic relief plan, carry out the first phase of traffic improvement construction to ensure the road is open; sixth: after the completion of the first phase of traffic improvement, install the tunnel project construction fence, level the construction site, and make the working surface have the conditions for construction operations. The following steps are taken to complete the construction of the retaining structure: site leveling, pile position measurement, concrete guide wall construction, pile driver positioning, casing drilling rig positioning, hanging and installing the first section of casing, measuring and controlling verticality, pressing the first section of casing, checking verticality, grabbing soil, pressing casing, measuring hole depth, removing loose soil, inspection, B pile (B pile refers to a type of pile in the support structure, which can be used to block groundwater seepage and prevent water gushing or landslides during tunnel excavation), hanging and placing steel cage, guide pipe installation, pouring concrete, pulling out pipes one by one, measuring concrete elevation, and moving the pile driver; the specific construction process is as follows: step 1: guide During wall construction, a reinforced concrete guide wall was constructed above the pile tops. The centerline coordinates of the pile rows (a structure used in construction projects for pit support, consisting of multiple single piles arranged in a row) were calculated, with the guide wall being 3.5 meters wide and 35 centimeters thick, using C25 concrete. The second step was to position the drilling rig and accurately determine the pile center, which served as a control point for drilling rig positioning. The third step was to drill holes. After the piles were in place, a hole was drilled to a depth of 2.5m to 3m of soil layer to clear obstacles, and then use the puller to sink the steel casing (steel casing specification 10mm thick, different sizes of steel casing are configured according to the depth of the fully weathered rock layer) into the fully weathered rock layer (for this project, the steel casing enters the fully weathered siltstone, fully weathered muddy siltstone, and fully weathered mudstone), and test the verticality of the steel casing. If it is unqualified, it will be corrected. If it is qualified, soil will be taken downward until the designed hole bottom elevation is reached; Step 4: Fabrication and installation of steel cage, the fabrication of steel cage must comply with the design drawings The design elevation can be calculated from the casing top elevation. The elevation calculation is correct during installation, with an allowable error of ±10mm. When lowering the steel cage, manual assistance is used to align the hole position, keeping it vertical, placing it gently and slowly. Generally, it is lowered slowly and gradually by forward and reverse rotation to prevent collision. It should be fixed immediately after it reaches the design elevation. Step 5: Concrete pouring. The concrete requires that the reinforced piles use underwater C35 concrete; the plain piles use super slow-setting C35 Concrete; Step 6: Pipe pulling and pile formation. The verticality of the pile should be monitored and checked during the drilling process; Step 7: Ground monitoring. During the casing pressing process, two people are arranged to use hammer balls to check the verticality of the casing from two mutually perpendicular directions (the verticality of the casing can also be checked by using a hammer ball with a verticality detection instrument, or the verticality of the casing can be checked by using other methods with a verticality detection instrument). If any deviation is found, it should be corrected at any time. This monitoring should be maintained throughout the drilling process of each pile. The specific process of concrete pouring construction is as follows: the concrete pouring conduit is connected with a screw thread and a rubber sealing ring, with an inner diameter of 25 cm; the conduit is slowly lowered into the hole by a crane, and the bottom of the conduit should be 30 cm to 50 cm higher than the bottom of the hole to ensure the discharge space at the bottom of the conduit. The top of the conduit is connected to a concrete funnel, and concrete flows into the funnel through a chute. When conditions are difficult, a crane can be used to lift the concrete into the funnel through the hopper. The funnel is filled with 2 cubic meters (m3). 3 ) After the concrete is poured, pull out the bottom cover of the funnel, pour concrete into the conduit, and keep pouring concrete continuously. During the pouring process, pay attention to the rise and fall of the water level in the hole, measure the actual height of the concrete surface at any time and calculate the buried depth of the conduit to ensure that the bottom end of the conduit is buried 2m to 6m below the concrete surface. After the concrete pouring is completed, gradually remove the casing and conduit; according to the buried depth of the conduit, remove 1 to 2 sections of the conduit each time. After the conduit is removed, it should be rinsed immediately for next use; when the casing is lifted, slowly pull it up and shake it left and right so that concrete can flow into the space occupied by the casing. At the same time, pay attention to whether the steel cage floats up. The buried depth of the casing should be controlled at about 2m. In order to ensure the quality of the designed pile top concrete, the concrete is poured to 0.5m above the pile top elevation. This part of concrete is chiseled off before the construction of the crown beam. The retarding time of the pile concrete is determined according to the pile-making time of the single pile. The pile-making time of the single pile is directly related to the geological conditions, pile length, pile diameter and drilling rig capacity. The calculation formula for the retarding time of the pile concrete is:

[0050] T=3t+K

[0051] Where T is the retarding time of the plain pile concrete, K is the reserve time, which is generally taken as 1.5t, and t is the time it takes for one of the piles A and B to be piled;

[0052] It should be noted that, in the embodiments of the present application, "concrete" and "concrete" are different names for the same concept.

[0053] Among them, in the above step 5, after the enclosure structure is completed, the main structure of the tunnel will be constructed; the specific process of the main structure construction is as follows: first: construction preparation work, after the foundation pit is excavated to the design elevation, the trench is inspected as soon as possible, and the structure is measured and laid out; the formwork support system of the side walls and top plates is designed and calculated, and a special plan for the tunnel formwork frame is prepared. After being submitted to experts for demonstration and approval, it is organized and implemented. The material is arranged in advance according to the construction progress, and the structural construction sequence, construction schedule, construction methods and technical requirements are carefully explained to the work team and all management personnel; second: the construction of the plain cushion layer, the cushion layer concrete is C20, 20cm thick, and the cushion layer construction is carried out closely following the excavation surface to prevent the base from being exposed. If the exposure time is too long, drain the water in the foundation pit, remove the loose soil in the foundation pit, clean and level the silt and debris on the top of the pull-out piles, silt and other debris. After the foundation pit is cleaned, use a rammer to fully compact the base, and measure the bearing capacity of the foundation. Report to the owner and engineer in writing in a timely manner. When paving the cushion concrete, control the surface elevation according to the pre-buried horizontal piles; use a flat vibrator to tamp the concrete. After the initial setting and before the final setting of the cushion concrete, perform a second calendering on the surface and fully maintain it to prevent loosening, sanding, and peeling. Control the cushion pouring thickness according to the pre-buried elevation control piles, and close and maintain the surface in time to ensure that there are no honeycombs, pits, or cracks on the cushion surface. Third: The bracket used for the main structure frame concrete construction is a disc-type full-span bracket. The layout of the bracket is calculated to ensure that the strength and stiffness meet the construction requirements. Each disc-type full-span bracket can withstand a vertical load of 8 tons to 9 tons (t). The calculation takes into account the side pressure of the side wall concrete, the weight of the top plate concrete, the weight of the formwork, the construction load (people, materials, machines, etc.) and the wind force acting on the formwork bracket and other possible loads. In the disc-type full-span bracket, the horizontal rods are spaced 60 cm in the longitudinal direction, and the disc-type poles are spaced 90 cm in the transverse direction. The spacing of the disc-type poles adjacent to the upper chamfer (the upper chamfer can refer to the edge chamfer of the top of the disc-type pole) in the transverse direction is 90 cm. The spacing is 60 cm to strengthen the rigidity of the longitudinal and transverse beams of the top plate and the horizontal and vertical belts of the side walls; in addition, the horizontal spacing of the buckle uprights can be positively correlated with the distance between the pankou uprights and the upper chamfer, that is, for any two adjacent pankou uprights, the first distance between the center point of the two adjacent pankou uprights and the upper chamfer is negatively correlated with the second distance between the two adjacent pankou uprights. The larger the first distance, the larger the second distance will be, and the smaller the first distance, the smaller the second distance will be. In this way, the closer to the upper chamfer, the denser the buckle uprights can be set, so that the structural strength near the upper chamfer can be improved, thereby achieving the effect of improving the overall structural strength.

[0054] Fourth: Formwork. The outer formwork of the concrete project uses the side wall of the enclosure structure. Before the construction of the side wall, the wall surface of the enclosure structure should be smoothed first. The formwork consists of three parts: bottom formwork, side wall and top formwork. They are assembled on site. The formwork uses a large steel formwork and is processed into a frame with angle steel and channel steel. The bakelite board is connected to the frame as a whole. It is processed into large blocks according to the design drawings and assembled on site, taking turnover into consideration. Fifth: Rebar. After the base waterproof coating is applied to meet the requirements, the bottom plate reinforcement is tied. The side wall and top plate reinforcement will be tied after the bottom plate concrete construction is completed and the inner formwork and bottom formwork are installed, and the design pre- Leave various joint steel bars, and all steel bars shall be tested in advance according to the requirements of the specifications, and laid out strictly according to the requirements of the design drawings, and reported to the engineer for approval. The steel bar binding and welding shall comply with the construction specifications; Sixth: Concrete pouring. Before pouring concrete, carefully design the concrete mix ratio and conduct various material experiments, and report to the supervising engineer for approval. Use commercial concrete, transport it with concrete tankers, and pump it into the mold with concrete pump trucks. In order to ensure that the concrete generates lower hydration heat during solidification, use slag cement with lower hydration heat. Repair the equipment before concrete transportation to ensure that the machine is in good condition.

[0055] In step 6 above, the tunnel structure is waterproofed. The specific process of waterproofing is as follows: Step 1: Self-waterproofing of the concrete structure. The design of the concrete structure's self-waterproofing should be based on the environmental conditions, selecting appropriate materials to meet the concrete's inherent impermeability, durability, and crack resistance requirements. Waterproof concrete should be formulated by adjusting the mix ratio and adding admixtures and additives. The structural concrete's impermeability grade, water-to-cement ratio, and minimum cementitious material dosage should be determined based on factors such as the concrete's strength and burial depth. The top slab concrete and the side wall concrete cast with it should incorporate appropriate amounts of active materials such as high-quality fly ash and slag, along with other anti-seepage measures such as shrinkage-reducing agents and expansion agents, to reduce drying shrinkage and thermal shrinkage. Other methods can also be used to reduce drying shrinkage and thermal shrinkage. For example, in summer, ice water mixing can be used to control the concrete's mold temperature to less than or equal to 30°C. Furthermore, concrete can be poured in layers, with each layer less than or equal to 400 mm thick and the pouring time for each layer less than the initial setting time of the concrete, to avoid the accumulation of internal temperature peaks. In addition, a cooling water pipe can be buried in the side wall concrete. The cooling water pipe can form a loop in the side wall concrete. After cooling water is passed into the cooling water pipe, the side wall concrete can be cooled. Optionally, when pouring the side wall concrete, multiple temperature sensors (such as concrete electronic thermometers) can be set in the side wall concrete. The temperature sensor can detect the temperature in the side wall concrete, and then the flow rate of the cooling water in the cooling water pipe can be controlled based on the temperature measured by the temperature sensor. For example, when the temperature sensor detects that the temperature in the side wall concrete is greater than 30 degrees, the flow rate of the cooling water in the cooling water pipe can be increased. When the temperature sensor detects that the temperature in the side wall concrete is less than 20 degrees, the flow rate of the cooling water in the cooling water pipe can be reduced. In this way, a closed-loop control is formed to accurately control the temperature in the side wall concrete, further reduce drying shrinkage and temperature difference shrinkage, and improve the formation quality of the side wall.

[0056] Furthermore, after the side walls are cast and formed in the above manner, they can be covered with plastic film or wet sacks to prevent rapid evaporation of moisture from the side wall surface. This allows for humidity control of the side walls to avoid shrinkage caused by humidity changes. Furthermore, after the side walls are cast, a wind speed sensor can be installed on the side walls. When the wind speed is greater than 4 meters per second, a windshield can be installed to shield the side walls and reduce shrinkage caused by air flow. The windshield can be an electrically foldable windshield, comprising a base and a foldable windshield located on the base. The foldable windshield is connected to the base and can be switched between a folded state and an unfolded state under the drive of the base. The electrically foldable windshield establishes a priority connection or a wireless connection with the wind speed sensor. Through this connection, the electrically foldable windshield can obtain the wind speed detected by the wind speed sensor. Furthermore, when the wind speed is greater than 4 meters per second, the base of the electrically foldable windshield can drive the foldable windshield to the unfolded state to shield the wind and prevent excessive wind speed from causing rapid evaporation of moisture from the side wall surface. When the wind speed is less than or equal to 4 meters per second, the base in the electric folding windshield device can drive the folding windshield to a folded state, so that the moisture on the side wall surface evaporates at a suitable speed.

[0057] Optionally, the base of the electric folding windshield device is arranged around the side wall, and the folding windshield is also arranged around the side wall, and the folding windshield includes four sub-folding windshields, which are respectively arranged outside the four directions of east, west, south and north of the side wall to block the wind in these four directions. A wind direction sensor is also provided on the side wall, and the electric folding windshield device establishes a priority connection or a wireless connection with the wind direction sensor. Through the connection, the electric folding windshield device can obtain the wind direction. Based on the wind direction and the wind speed obtained by the above-mentioned wind speed sensor, when the wind speed is greater than 4 meters per second, the electric folding windshield device can control the sub-folding windshield in the corresponding direction to be transformed into an unfolded state to block the wind in this wind direction. This can further enhance the flexibility of the electric folding windshield device in blocking external wind.

[0058] The second step: waterproof membrane construction, the side wall (enclosure section) and the bottom plate are all made of 1.5mm thick pre-laid polymer waterproof membrane. When the pre-laid waterproof membrane is laid by the external waterproofing and internal pasting method, the bottom plate is laid by the empty laying method, and the facade is laid by the mechanical fixing method. The membranes are tightly pasted together; the top plate concrete adopts a flexible waterproof layer, and the flexible waterproof layer adopts a coating waterproof layer. The flexible waterproof layer is set on the water-facing side of the structure. The waterproof coating type of the coating waterproof layer is selected according to the engineering environment, climatic conditions, construction methods, structural construction form, and engineering waterproof grade requirements. At the same time, the wet base should use a single-component polyurethane waterproof coating or polymer cement waterproof coating that has a certain adhesion to the wet base surface. The selected coating type should have good water resistance, durability, corrosion resistance, good elongation and the ability to adapt to the deformation of the base. The thickness of the waterproof coating is 2.0mm. The protective layer of the coating waterproof layer should be determined according to the specific parts of the structure; the internal and external corners of the structural concrete where the waterproof layer is applied should be made into arcs or 45° angles. The size of the internal and external corners is determined according to the type and thickness of the waterproof material; at the corners, internal and external corners and special parts, a reinforcement layer should be added to strengthen The width of the layer should not be less than 500mm; the third step: waterproofing of construction joints. The spacing of construction joints should not be greater than 16m. The horizontal construction joints of the wall should not be left at the maximum shear force or at the junction of the bottom plate and the side wall. Optionally, the horizontal construction joints of the wall are located at one-third to one-quarter of the wall height from bottom to top, and left on the wall not less than 300mm above the bottom plate surface. When there are reserved holes in the wall, the distance between the construction joint and the edge of the hole should be not less than 300mm; the fourth step: waterproofing of expansion joints. The waterproofing measures taken at the expansion joints can meet the differential settlement and longitudinal The sealing and waterproofing requirements during expansion and contraction are met by adopting multiple defense methods such as embedded waterstop, external waterstop, internal removable waterstop and sealant caulking. The embedded waterstop, external waterstop and internal removable waterstop adopt medium-hole or Ω-type waterstop. The fifth step: pile head waterproofing. The waterproof material selected for the pile head has the properties of increasing the density of concrete, good adhesion with the pile head concrete and steel bars, water resistance and moisture curing. If the base plate is paved with a flexible waterproof layer, the pile head rigid waterproof layer and the base plate flexible waterproof layer form a continuous and closed waterproof system.

[0059] In step seven, after the main tunnel structure is completed, the installation of auxiliary structures will be carried out. These auxiliary structures include electrical installation, ventilation equipment installation, decoration, and fire protection. Electrical installation primarily includes tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection and grounding, and other works, pump room and auxiliary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcast system, emergency telephone system, wireless communication system, UPS uninterruptible power supply system, and other integrated pipelines. The specific process for ventilation equipment installation includes the installation and commissioning of fans and control boxes within the tunnel. The ventilation control box installation process includes fan unpacking inspection, pre-embedding of fan components, welding of connection accessories and tensile strength testing, fan installation, cable laying, control box installation and cable splicing, and acceptance testing. Fire protection works include fire water sources, firefighting facilities, tunnel fire water supply system, fire hydrant water supply system, aqueous film-forming foam firefighting system, fire extinguishers, and ground fire protection.

[0060] In the above step eight, the tunnel construction record reports are summarized, and the construction process of each segment structure is summarized and analyzed to write a results report to provide support for the subsequent optimization of the construction process.

[0061] Based on the above, the advantages of the present invention are that, by relocating or modifying greening facilities, damage to the environment during tunnel construction is avoided, and the normal ecological environment is avoided from being affected; through the electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering and other auxiliary structures carried out in the tunnel, real-time monitoring of the tunnel is achieved, and accidents can be discovered in time to avoid affecting the normal passage of the tunnel; through the self-waterproofing of the concrete structure, waterproof membrane construction, construction joint waterproofing, expansion joint waterproofing and pile head waterproofing completed during the tunnel construction process, the waterproof performance of the tunnel is effectively improved, and in the face of severe weather, the tunnel is effectively prevented from cracking or rainwater from penetrating into the tunnel, thereby improving the safety of the tunnel.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A construction process for an urban tunnel in an ecologically sensitive area, comprising the following steps: Step 1: Traffic diversion; Step 2: Greening relocation; Step 3: Construction preparation; Step 4: Enclosure construction; Step 5: Main structure construction; Step 6: Waterproofing construction; Step 7: Ancillary structure construction; Step 8: Compilation of results report; It is characterized by: In step 1 above, a reasonable traffic organization plan will be formulated in conjunction with traffic police based on actual traffic conditions. Traffic diversion plans will be prepared based on the starting and destination points of vehicles. Multiple carriers will be used to form high-density, three-dimensional, real-time, rolling guidance, improve information symmetry, and induce balanced traffic flow distribution. Traffic coordinators will be arranged at important intersections affected by construction. In the above step 2, the greening facilities within the construction area are relocated or modified to avoid affecting the normal ecological balance; In the above step 3, preparatory work before construction is done to create conditions for the formal construction of the tunnel project; In the above step 4, the construction of the retaining structure is completed by bored cast-in-place piles and bored interlocking piles; In the above step 5, after the enclosure structure is completed, the main structure of the tunnel is constructed; In the above step 6, waterproofing construction is performed on the tunnel structure; In the above step 7, after the main structure of the tunnel is completed, the auxiliary structure is installed; In the above step eight, the tunnel construction record reports are summarized, and the construction process of each segment structure is summarized and analyzed to write a results report to provide support for the subsequent optimization of the construction process.

2. The construction process for an urban tunnel in an ecologically sensitive area according to claim 1, characterized in that: In step three, construction preparation specifically includes: first, setting up temporary facilities, installing fencing, and building temporary construction access roads; second, obtaining construction machinery and testing equipment, reviewing control point data, establishing an on-site construction control network, and checking underground pipelines; third : Establish the conductor network of this section; Fourth: Complete the construction of the temporary project; Fifth: According to the preset traffic relief plan, the first phase of traffic improvement construction will be carried out to ensure the accessibility of the road; Sixth: After the completion of the first phase of traffic reform, the tunnel construction fence will be installed and the construction site will be leveled to ensure that the working surface has the conditions for construction.

3. The construction process for an urban tunnel in an ecologically sensitive area according to claim 1, characterized in that: In step 4, the sequence of the single pile construction process is: site leveling, measuring and placing pile positions, constructing concrete guide walls, positioning the pile driver, positioning the casing drill, hoisting and installing the first section of casing, measuring and controlling verticality, pressing in the first section of casing, checking verticality, taking soil with a grab bucket, pressing in the casing, measuring the hole depth, removing loose soil, inspection, hoisting the steel cage of pile B, installing the guide tube, pouring concrete, pulling out the tubes one by one, measuring the concrete elevation, and moving the pile driver.

4. The construction process for an urban tunnel in an ecologically sensitive area according to claim 3, characterized in that: In the step 4, the specific construction process is as follows: the first step: guide wall construction, a reinforced concrete guide wall is constructed on the top of the pile, and the coordinates provided in the design drawings are set 100 mm outward to offset the reduction in the clearance of the foundation pit structure caused by the inward displacement and deformation of the interlocking pile under the action of the external soil pressure during foundation pit excavation. The coordinates of the center line of the pile row are calculated. The guide wall is 3.5 meters wide and 35 cm thick, and the material is C25 concrete; the second step: the drilling rig is in place, and the center position of the pile is determined as the control point for the positioning of the drilling rig; the third step: soil excavation and hole formation. After the pile foundation is in place, a soil layer with a depth of 2.5 to 3 meters is taken and obstacles are cleared. Then, a steel casing is sunk into the fully weathered rock layer using a drilling machine. The specification of the steel casing is 10 mm thick. The verticality is detected. If the verticality does not reach the target verticality, correction is performed. If the verticality reaches the target verticality, soil is taken downward until the designed hole bottom elevation is reached. Step 4: Fabrication and installation of the steel cage. The steel cage is hoisted by a crane. The design elevation is determined by the casing top elevation. The installation error is ±10 mm. The steel cage is lowered by rotating it forward or backward to prevent collision. It is fixed after it reaches the design elevation. Step 5: Concrete pouring: reinforced piles are made of underwater C35 concrete; plain piles are made of super slow-setting C35 concrete; Step 6: Pull out the pipe to form the pile, monitor and check the verticality of the pile during the drilling process; Step 7: Ground monitoring, during the casing pressing process, use a hammer ball to check the verticality of the casing from two mutually perpendicular directions, and correct any deviation if found.

5. The construction process for an urban tunnel in an ecologically sensitive area according to claim 4, characterized in that: In the step 4, the specific process of concrete pouring construction is as follows: the concrete pouring conduit is connected with a screw thread and a rubber sealing ring, and the inner diameter is 25 cm; the conduit is slowly lowered into the hole by a crane, and the bottom of the conduit is 30 cm to 50 cm higher than the bottom of the hole. The upper end of the conduit is connected to a concrete funnel, and concrete flows into the funnel through a chute. When conditions are difficult, a crane can be used to lift the concrete into the funnel through a hopper. After more than 2 cubic meters of concrete is placed in the funnel, the bottom cover of the funnel is pulled out, and concrete is poured into the conduit, and the concrete is continuously poured. During the pouring process, the water level in the hole is detected and the actual concrete surface is measured. The height and buried depth of the conduit are calculated so that the bottom end of the conduit is buried 2 to 6 meters below the concrete surface. After the concrete pouring is completed, the casing and conduit are gradually removed. According to the buried depth of the conduit, 1 to 2 sections of the conduit are removed each time. After the conduit is removed, it is rinsed clean for the next use. When the casing is lifted, it is slowly pulled up and shaken left and right to allow the concrete to flow into the space occupied by the casing. At the same time, pay attention to whether the steel cage floats up. The casing is buried at a depth of about 2 meters. The concrete is poured to 0.5 meters above the pile top elevation. This part of the concrete is chiseled off before the construction of the crown beam. The calculation formula for the delayed setting time of the plain pile concrete is: T = 3t + K; Where T is the retarding time of the plain pile concrete, K is the reserve time, which is generally taken as 1.5t, and t is the time it takes to form one of the piles, A and B.

6. The construction process for an urban tunnel in an ecologically sensitive area according to claim 1, characterized in that: In step 5, the specific process of the main structure construction is as follows: first, after the foundation pit is excavated to the designed elevation, the trench is inspected and the structure is measured and laid out; the formwork support system for the side walls and top plate is designed and calculated, and a tunnel formwork support plan is prepared and implemented, and material supply is arranged according to the construction progress; Second: Construction of plain cushion layer. The cushion layer concrete is C20 and 20 cm thick. The cushion layer construction is carried out closely following the excavation surface to avoid the base being exposed for too long. The water in the foundation pit is removed, the loose soil in the foundation pit is cleared, and the silt and debris on the top of the pull-out piles are cleaned and leveled. After the foundation pit is cleaned, the base is fully compacted with a rammer, and the bearing capacity of the foundation is measured. When the cushion layer concrete is spread, the surface elevation is controlled according to the pre-buried horizontal piles; the concrete is vibrated with a flat vibrator. After the initial setting and before the final setting of the cushion layer concrete, the surface layer of the cushion layer concrete is calendered for the second time and maintained to prevent loosening, sanding and peeling. The cushion layer pouring thickness is controlled according to the pre-buried elevation control piles, and the surface is collected and cured to ensure that there are no honeycombs, pitting and cracks on the cushion layer surface. Third: The bracket used for the concrete construction of the main structure frame is a disc-type full-floor bracket. Each disc-type upright in the disc-type full-floor bracket can withstand a vertical load of 8 to 9 tons. The vertical load includes the side pressure of the side wall concrete, the weight of the top slab concrete, the weight of the formwork, the construction load, and the wind force acting on the formwork bracket. In the disc-type full-floor bracket, the horizontal bars are spaced 60 cm in the longitudinal direction, the disc-type uprights are spaced 90 cm in the transverse direction, and the disc-type uprights adjacent to the chamfer in the transverse direction are spaced 60 cm to strengthen the rigidity of the longitudinal and transverse beams of the top slab and the side wall transverse belts and vertical belts; Fourth: Formwork. The outer formwork of the concrete project uses the side wall of the enclosure structure. Before the side wall is constructed, the wall surface of the enclosure structure must be smoothed first. The formwork consists of three parts: bottom formwork, side wall, and top formwork. It is assembled on site. The formwork uses steel formwork, which is processed into a frame with angle steel and channel steel. The bakelite board is connected to the frame as a whole. It is processed into blocks according to the design drawings and assembled on site. Fifth: After the base waterproof coating is applied, the bottom plate reinforcement is tied. The side wall and top plate reinforcements are tied after the bottom plate concrete construction is completed and the inner formwork and bottom formwork are installed, and the joint reinforcement is reserved; Sixth: Concrete pouring, use commercial concrete, transported by concrete tank trucks, and pumped into the mold by concrete pump trucks. Slag cement is used to reduce the hydration heat generated by the concrete during solidification.

7. The construction process for an urban tunnel in an ecologically sensitive area according to claim 1, characterized in that: In step 6, the specific process of waterproofing construction is as follows: Step 1: Self-waterproofing of the concrete structure. The self-waterproofing design of the concrete structure determines the material according to the environmental conditions to meet the requirements of the concrete's own impermeability, durability and crack resistance; Waterproof concrete is prepared by adjusting the mix ratio and adding admixtures and additives. The structural concrete impermeability grade, structural concrete water-cement ratio and minimum amount of cementitious materials are determined according to the strength of the concrete structure and the depth of structural burial. Fly ash and slag are added to the top slab concrete and the side wall concrete cast together with the top slab concrete to reduce shrinkage and temperature difference shrinkage. The second step: construction of waterproof membrane. The side walls and bottom slabs are pre-laid with 1.5 mm thick polymer waterproof membrane. When the pre-laid waterproof membrane is laid by the external anti-internal pasting method, the bottom slab is laid by the empty laying method and the facade is laid by the mechanical fixing method. The membranes are tightly pasted to each other. The top slab concrete adopts a flexible waterproof layer. The flexible waterproof layer adopts a coating waterproof layer. The flexible waterproof layer is set on the water-facing side of the structure. The waterproof coating type of the coating waterproof layer is determined according to the engineering environment, climatic conditions, construction methods, structural structure and engineering waterproof grade requirements. At the same time, the wet base layer uses a single-component polyurethane waterproof coating or polymer cement waterproof coating with adhesion to the wet base surface. The selected coating type has good Water resistance, durability, corrosion resistance, elongation and the ability to adapt to deformation of the base layer. The thickness of the waterproof coating is 2.0 mm. The protective layer of the coating waterproof layer is determined according to the specific part of the structure. The internal and external corners of the structural concrete for applying the waterproof layer are made into arcs or 45° angles. The size of the internal and external corners is determined according to the type and thickness of the waterproof material. A reinforcement layer is added at the corners and internal and external corners. The width of the reinforcement layer is greater than or equal to 500 mm. The third step: waterproofing the construction joints. The spacing of the construction joints is less than or equal to 16 meters. The horizontal construction joints of the wall are at the maximum shear force. In the area outside the junction of the large area or the bottom plate and the side wall, when there are reserved holes in the wall, the construction joint is greater than or equal to 300 mm from the edge of the hole; Step 4: Waterproof the expansion joint. The waterproof measures taken at the expansion joint can meet the sealing and waterproof requirements during the differential settlement and longitudinal expansion of the structures at both ends of the joint. Use embedded waterstops, external waterstops, internal removable waterstops and sealant caulking to carry out multiple defenses. The embedded waterstops, external waterstops and internal removable waterstops use medium-hole or Ω-type waterstops; Step 5: Pile head waterproofing. The waterproof material selected for the pile head has the ability to increase the density of the concrete, the adhesion with the pile head concrete and steel bars, water resistance and moisture curing properties. If a flexible waterproof layer is laid on the base plate, the rigid waterproof layer of the pile head and the flexible waterproof layer of the base plate form a continuous and closed waterproof system.

8. The construction process for an urban tunnel in an ecologically sensitive area according to claim 1, characterized in that: In step seven, the installation and construction of the auxiliary structures include electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering. The electrical installation includes: tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection and grounding and others, pump room and ancillary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcasting system, emergency telephone system, wireless communication system and UPS uninterruptible power supply system.

9. The construction process for an urban tunnel in an ecologically sensitive area according to claim 8, characterized in that: In step seven, the specific process of ventilation equipment installation includes the installation and commissioning of the fan and control box in the tunnel. The ventilation control box installation process includes fan unpacking inspection, pre-embedding of fan parts, welding of connection accessories and tensile strength test, fan installation, cable laying, control box installation and cable connection, and test acceptance. In step seven, the fire protection project includes fire water sources, fire protection facilities, tunnel fire water supply system, fire hydrant water supply system, water film-forming foam fire protection system, fire extinguishers and ground fire protection.

10. A construction process for urban tunnels in ecologically sensitive areas, characterized in that: include: Step 1: Traffic diversion; Step 2: Greening relocation; Step 3: Construction preparation; Step 4: Enclosure construction; Step 5: Main structure construction; Step 6: Waterproofing construction; Step 7: Ancillary structure construction; Step 8: Compilation of results report; In the step 1, a traffic diversion plan is determined according to the starting point and destination of the vehicle; In the second step, the greening facilities within the construction area are relocated or modified; In step three, construction preparation includes: first, setting up temporary facilities, installing fences, and building temporary construction access roads; second, obtaining construction machinery and testing equipment, reviewing control point data, establishing an on-site construction control network, and checking underground pipelines; third, establishing a conductor network for this section; fourth, completing the construction of the major temporary project; fifth, carrying out the first phase of traffic improvement construction to ensure accessibility according to the preset traffic relief plan; sixth, after the completion of the first phase of traffic improvement, installing tunnel construction fences, leveling the construction site, and making the working surface ready for construction operations; In the step 4, the construction of the retaining structure is completed by bored cast-in-place piles and bored interlocking piles; In the step 5, after the enclosure structure is completed, the main structure of the tunnel is constructed; In the step 6, waterproofing is performed on the tunnel structure; In step seven, after the construction of the main tunnel structure is completed, the installation and construction of the auxiliary structure is carried out. The installation and construction of the auxiliary structure includes electrical installation, ventilation equipment installation, decoration engineering and fire protection engineering. The electrical installation includes: tunnel power supply and distribution, tunnel power distribution, tunnel lighting, lightning protection and grounding and others, pump room and ancillary room lighting, tunnel management center, computer network system, closed-circuit television surveillance system, traffic video monitoring, electromechanical equipment automatic control system, fire alarm and linkage control system, wired broadcasting system, emergency telephone system, wireless communication system and UPS uninterruptible power supply system.

Images