BIM (Building Information Modeling)-based comprehensive construction method for shallow-buried tunnels in residential areas and coastal tidal areas

Abstract

The invention relates to a BIM-based residential area and coastal tidal area shallow-buried tunnel comprehensive construction method. The method comprises the following steps: step 1, carrying out deep fusion application of BIM, VR and GIS technologies; 2, measuring and positioning; step 3, advanced geological forecast; fourthly, tunnel construction is conducted; the tunnel construction comprises the steps of construction preparation, tunnel opening waterproof and drainage system construction, tunnel opening section construction, tunnel body excavation and primary support, monitoring and measurement, secondary lining, cable trough and ditch construction, and tunnel inner road surface and traffic safety electromechanical engineering construction. The influence on surrounding buildings and structures in the construction process is reduced.

Description

Technical Field

[0001] The present invention relates to the field of coastal construction, and in particular to a comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM. Background Art

[0002] A certain project is located in the coastal tidal zone, close to the coastline, and the construction site is embedded in the mountains with gullies and ravines, with extremely complex terrain conditions. The project area not only has to face the challenges of various extreme natural climates such as typhoons, floods, droughts, strong winds, rare tornadoes and even hail, but also faces construction difficulties such as the shallow depth of the tunnel and the densely distributed large number of residential houses and historical tombs above it. The safety risks and difficulties of the construction are extremely high.

[0003] 1. The construction of shallow tunnels is easily affected by surface activities, such as ground subsidence and collapse. The impact on the surrounding environment is greater, such as noise and vibration problems are more prominent. At the same time, tunnel construction requires more precise control of excavation progress and support measures. At the same time, the safety of facilities such as buildings above the tunnel and underground pipelines must also be considered, which increases the difficulty and complexity of construction.

[0004] 2. Traditional methods of tunnel construction mainly include drilling and blasting, tunnel boring machine and shield method, but they each have obvious shortcomings. For example, the drilling and blasting method has large construction interference, slow speed, over-excavation and under-excavation are difficult to avoid, and there is a high safety risk; although the tunnel boring machine method performs well in medium-hard rock formations, the equipment cost is high, the adaptability is limited, the working environment is harsh, and the auxiliary work time is long; the shield method faces challenges due to high construction complexity, expensive equipment cost, difficult surface deformation control, and low reuse rate.

[0005] 3. Tunnel construction Traditional measurement methods include leveling and traverse measurement to control the plane position and axis direction of the tunnel. However, due to the complex construction environment of engineering tunnels, traditional measurement methods are easily restricted and disturbed by construction activities, affecting the accuracy of the measurement results. At the same time, tunnel projects are usually large-scale projects, requiring multiple measurements to obtain comprehensive and accurate data. Traditional measurement methods have problems such as time-consuming instrument and equipment debugging and data processing, resulting in slow measurement progress. In some special cases, such as when the tunnel section is large and the height is high, traditional measurement methods may find it difficult to achieve high measurement accuracy. For example, the measurement points of the arch crown sinking and the arch foot are often difficult to measure accurately after the lower step is excavated. In addition, traditional measurement methods are mainly based on two-dimensional plane measurements, and cannot truly understand the three-dimensional deformation state of the tunnel.

[0006] 4. Traditional geological prediction methods for tunnel construction include geological survey, drilling, physical exploration, etc. Although the geological survey method can provide relatively comprehensive geological data, it is easy to miss the unfavorable geology in front of the tunnel that has not been excavated, and the prediction distance is relatively short. Other methods also have relatively high costs and long construction periods, which have a certain impact on the construction progress. The prediction accuracy is easily affected by many factors, such as the complexity of geological conditions and data processing methods. Under certain special geological conditions (abundant groundwater in the project), the prediction effect may be subject to certain restrictions.

[0007] 5. Since there are houses, communication cables, power cables, pipelines, etc. not far from the tunnel entrance that need to be relocated in advance, many departments need to be coordinated in the early stage of construction, and there is a risk of idle workers due to untimely relocation. There are many buildings close to the tunnel, such as houses, schools, temples, etc. The use of blasting construction may have a certain impact on the surrounding buildings and residents' lives, so coordination is difficult. The tunnel entrance has limited space, and it is difficult to arrange construction machinery and equipment, materials, workers' dormitories, etc. Summary of the invention

[0008] The present invention aims to overcome the defects of the prior art and provide a comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM, so as to solve the problems of great construction difficulty and great safety risks in the construction process in coastal tidal zones, areas with complex topography and shallow tunnel burial.

[0009] In order to solve the above-mentioned technical problems, the present invention is achieved as follows: A comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM, characterized in that it includes the following steps: Step 1: Deep integration and application of BIM, VR and GIS technologies; Step 2: Measurement and positioning; Step 3: Advanced geological forecast; Step 4: Tunnel construction; Tunnel construction includes: construction preparation, construction of tunnel entrance drainage system, tunnel entrance section construction, tunnel body excavation and initial support, monitoring and measurement, secondary lining, cable trough and ditch construction, tunnel pavement, and traffic safety and electromechanical engineering construction.

[0010] The BIM-based comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas is characterized in that step one comprises: 1. Preliminary preparation (1) Project approval and survey and design (2) BIM model construction: Using BIM technology, a three-dimensional BIM model of the tunnel is constructed based on geological survey data and other design information. The model should include all key information such as tunnel structure, support system, excavation method, drainage system, etc. (3) VR environment construction: Based on the BIM model, VR technology is used to build a virtual reality construction environment. This environment should simulate the tunnel construction scene as realistically as possible, including geological conditions, construction equipment, personnel configuration, etc. 2. Digital migration planning (1) Data collection and collation: Conduct a comprehensive on-site survey of housing, communication cables, power cables, pipelines, etc. around the tunnel entrance to collect relevant information such as location, size, material, etc.; obtain basic information such as topographic maps, geological maps, and planning maps of the tunnel area to ensure the accuracy and completeness of the data; (2) 3D modeling: Using GIS technology, the collected data is imported into the GIS platform for spatial analysis and processing to generate a 3D terrain model around the tunnel entrance. Combined with BIM technology, accurate 3D modeling of structures such as housing, communication cables, power cables, and pipelines is performed, including their geometric shapes, attribute information, etc. (3) Digital migration planning: In the 3D model, the migration path is planned and optimized according to the actual conditions of the tunnel construction and surrounding structures. Considering factors such as time, cost, and safety during the migration process, a detailed migration plan and scheme is formulated. The simulation function of GIS is used to rehearse the migration process and verify the feasibility and rationality of the migration scheme. (4) Plan review and adjustment: Organize experts to review the digital migration plan and put forward modification opinions and suggestions; adjust and optimize the migration plan based on the review results to ensure the feasibility and cost-effectiveness of the plan; 3. Intelligent monitoring system (1) System design and development: Design the architecture and functional modules of the intelligent monitoring system according to the requirements of the migration plan; develop the software platform of the intelligent monitoring system to realize functions such as data collection, processing, analysis and display; (2) Layout and installation of monitoring equipment: Layout monitoring equipment such as cameras and sensors along the migration path and in key locations around the area; ensure the stability and reliability of the monitoring equipment and conduct regular inspections and maintenance; (3) Real-time monitoring and data analysis: Using intelligent monitoring systems to monitor the progress of migration and the impact on the surrounding environment in real time, including the displacement, deformation, and damage of structures; processing and analyzing monitoring data to generate migration progress reports and surrounding environmental impact assessment reports; (4) Early warning and alarm mechanism: Set early warning and alarm thresholds. When the monitoring data exceeds the threshold, the system automatically issues an early warning or alarm signal; promptly notify relevant personnel to take corresponding measures to ensure the safety and smooth progress of the migration work; (5) System maintenance and upgrade: Regularly maintain and upgrade the intelligent monitoring system to ensure the stability and accuracy of the system; continuously optimize and expand the system's functions and application scope based on actual needs and technological development.

[0011] The BIM-based comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas is characterized in that step 2 comprises: 1. Re-survey and encryption of the plane control network of this tunnel (1) Re-survey of the basic plane control network (CPⅠ) and encryption of the line plane control network (CPⅡ); after the handover piles are completed, immediately organize surveyors to carry out re-survey of the plane control network; (2) The plane control network of the tunnel is the basic plane control network (CPⅠ), which is provided by the design unit and requires high measurement accuracy. The basic plane control network (CPⅠ) is usually measured by GPS Class B. After the control points are handed over, a measurement plan is formulated based on the handover data of the design unit, and all CPⅠ control points are re-measured with the same accuracy using a dual-frequency static receiver. Various tolerances and accuracy requirements (based on this) should meet the requirements of the Technical Specifications for Construction Surveying of Highway Tunnel Construction. (3) After the resurvey of CPI control points is completed, the field observation records, original observation data, original data submitted by the design institute, and resurvey accuracy analysis and technical reports shall be reported or saved; the CPI control network adopts the baseline double difference fixed solution to perform three-dimensional unconstrained adjustment; CPII encryption should be combined with CPI to form an auxiliary network, and constrained adjustment and coordinate transformation should be performed through the CPI control network of the joint survey; 2. Elevation control measurement: ①Re-survey of leveling points ②Encryption of the leveling network 3. Hole measurement The construction control points are set up through the layout of approach traverses and approach leveling routes to establish entry points, and then the plane and elevation control points are introduced into the tunnel through the entry points to provide underground plane and elevation basis for tunnel excavation; the point near the tunnel entrance is in line of sight with the GPS point or precision traverse point, and the orientation should have the most favorable graphics; the approach traverse measurement is carried out with a 2″ or higher level total station according to the requirements of the first level traverse; 4. Construction layout measurement The three-dimensional polar coordinate method is used for surveying. In order to strengthen the verification conditions of the stakeout points, two other known traverse points can be used as the starting data, and the same method can be used to check whether the stakeout points are correct, or the coordinate measurement function of the total station can be used to measure the coordinates of the stakeout points with two other known traverse points; 5. Tunnel penetration measurement About 50 meters before the tunnel is broken through, the number of construction measurements should be increased, and the entire line of the control wire should be re-surveyed until the tunnel is guaranteed to be broken through; after the tunnel is broken through, the lateral breakthrough error, longitudinal breakthrough error and elevation breakthrough error should be measured.

[0012] The BIM-based comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas is characterized in that step three includes: 1. Principle: According to the actual situation of the tunnel project line length, geological conditions, etc., adhere to the principle of "three combinations" of advanced geological prediction and risk target section division, that is, "combination of geology with geophysical exploration and drilling, combination of inside and outside the tunnel, and combination of length and different geophysical exploration methods", and adopt the corresponding prediction plan based on the tunnel risk classification; 2. Application of geological radar 1) Use geological radar (GPR) for short-range (30-50m) microscopic near-term forecasts. Before use, calibrate the geological radar, including equipment performance testing, parameter setting verification, etc., to ensure data accuracy; 2) Detection plan formulation: formulate a geological radar detection plan based on the tunnel construction progress and geological survey data, clarify the detection area, detection frequency and detection time; consider factors such as tunnel excavation direction and cross-section size to determine the layout and scanning path of the geological radar; 3) When it is speculated that the tunnel may have other unfavorable geological conditions such as water-rich areas, such as synclines, fault fracture zones, etc., advanced horizontal drilling is generally carried out 10 to 20 meters in advance; 4) On-site detection operation: Arrange the geological radar on the tunnel excavation face or working face, ensuring that it is parallel or perpendicular to the tunnel axis in order to obtain comprehensive geological information; scan according to the detection plan, pay attention to controlling the scanning speed and distance, and avoid missing or repeated scanning; 5) Data processing and interpretation: Collect geological radar detection data, use professional software to process and analyze the data, and generate geological radar images; identify geological anomalies such as faults and karst caves ahead of tunnel excavation based on image features, and determine their location, scale and nature; 6) Early warning and response measures: Based on the geological radar detection results, timely issue geological anomaly warnings to remind construction personnel to pay attention to safety; formulate corresponding response measures for detected geological anomalies, such as adjusting the construction plan, strengthening support measures, etc.; 3. Ultrasonic detection application 1) Equipment selection and layout: Select ultrasonic detection equipment suitable for the tunnel geological conditions to ensure that its detection range and accuracy meet the construction requirements; arrange ultrasonic detectors on the tunnel excavation face or working face to ensure that they are parallel or perpendicular to the tunnel axis in order to obtain accurate groundwater information; 2) Detection parameter setting: according to the tunnel geological conditions and construction requirements, set the parameters of the ultrasonic detector, such as transmission frequency, receiving sensitivity, etc.; consider the flow rate and direction of groundwater and other factors to determine the scanning mode and time interval of ultrasonic detection; 3) On-site detection and recording: Conduct ultrasonic detection according to the detection plan, pay attention to controlling the detection distance and angle, and avoid interference and errors; record the detection results, including ultrasonic propagation time, echo intensity and other parameters, to provide a basis for subsequent data analysis; 4) Data processing and analysis: Use professional software to process and analyze ultrasonic detection data to generate images or reports of groundwater distribution and flow conditions; based on the analysis results, determine the distribution range, flow velocity, flow direction and other characteristics of groundwater around the tunnel; 5) Drainage and waterproofing measures: According to the ultrasonic detection results, formulate corresponding drainage and waterproofing measures, such as setting up drainage ditches and installing waterproof curtains, etc.; pay close attention to the changes in groundwater during the construction process, and adjust the drainage and waterproofing measures in time to ensure construction safety; 4. Advanced horizontal drilling When the geological radar predicts that the surrounding rock ahead has poor geology, advance horizontal drilling is adopted in front. The advance drilling distance is generally 30m, with an overlap of 5m to ensure that there are enough safe rock pillars. The drilling equipment uses a down-the-hole drill or a geological drill. The advance drilling is arranged in sections with geophysical anomalies, sections with poor geological bodies in the design, complex sections where the geological conditions need to be further explored, and other sections with the danger of sudden water and mud. In general sections, a 30m exploration hole perpendicular to the face is drilled in the middle of the face, and 3 to 5 30m exploration holes perpendicular to or inclined to the face are drilled in key sections. The specific outward angle is determined based on the on-site forecast and analysis of geological data.

[0013] The BIM-based comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas is characterized in that step 4 includes: The tunnel follows the guiding ideology of "comprehensive planning, balanced production, priority, segmented organization, highlighting difficulties, and orderly advancement". The tunnel is excavated from a single entrance and constructed from the entrance to the exit. The open tunnel and portal are constructed using the open-cut method, and the blind tunnel section is constructed using the step method, reserved core soil method, and CD method. 1. Overall construction sequence of the tunnel: construction preparation → construction of tunnel entrance drainage system → construction of tunnel entrance section → tunnel body excavation and initial support → monitoring and measurement → secondary lining → cable trough and ditch construction → road surface inside the tunnel → traffic safety and electromechanical engineering construction; 2. Tunnel excavation (1) Mixed tunneling 1) Equipment selection and design: According to the tunnel geological survey report, clarify the distribution of strata along the tunnel, especially the alternation of hard rock and soft rock; select a hybrid tunnel boring machine with the ability to tunnel hard and soft rocks, and ensure that its design parameters (such as cutterhead diameter, motor power, propulsion force, etc.) meet the requirements of tunnel construction; communicate with equipment suppliers to carry out customized design according to the specific conditions of the tunnel, such as the configuration of cutterhead tools and the optimization of rock breaking methods; 2) Operation mode switching: During the excavation process, according to the lithology of the current excavation stratum, the machine can flexibly switch to the appropriate working mode through the control panel or remote control system of the tunnel boring machine. In the hard rock mode, the cutter head speed and thrust are increased, and sharper cutters are used to efficiently break the rock; in the soft rock mode, the speed and thrust are appropriately reduced to reduce cutter wear and energy consumption; 3) Performance monitoring and adjustment: Use the sensors on the tunnel boring machine to monitor key parameters such as tunneling speed, cutterhead wear, and motor temperature in real time; adjust tunneling parameters such as tunneling speed and thrust distribution in a timely manner based on the monitoring data to maintain optimal tunneling efficiency; 4) Maintenance and care: Develop a detailed maintenance and care plan for the tunnel boring machine, including regular inspection of tool wear, replacement of damaged parts, cleaning of the cooling system, etc.; in formations where hard and soft rocks alternate, pay special attention to tool wear and replace severely worn tools in a timely manner to avoid affecting tunneling efficiency and equipment life; (2) Application refinement of electronic control systems 1) Parameter monitoring: Install and configure the electronic control system of the roadheader to ensure real-time monitoring of key parameters such as cutter head speed, thrust, torque, oil temperature, and water pressure; set parameter alarm thresholds. When the parameters exceed the set range, the system automatically alarms and prompts the operator to take corresponding measures; 2) Remote monitoring and diagnosis: Establish a remote monitoring center to transmit the data of the roadheader to the monitoring center in real time via a wireless network; set up professional software in the monitoring center to analyze the data of the roadheader in real time and predict potential fault points; When a roadheader fails, the remote diagnosis system can be used to quickly locate the cause of the failure, provide remote technical support or guide on-site repairs; 3) Data management and analysis: Regularly back up and store the operation data of the roadheader and establish a roadheader operation database; use data analysis tools to conduct in-depth analysis of data such as tunneling efficiency, energy consumption, and tool wear to provide decision support for roadheader performance optimization and construction management; 4) System upgrade and maintenance: regularly upgrade the software of the electronic control system to ensure the latest and stability of the system functions; regularly maintain the system, including checking sensors, line connections, controllers, etc., to ensure the normal operation of the system; 3. Tunnel excavation rig composition Door frame assembly: The door frame is a door-shaped frame welded with steel of different specifications, with a total of 3 rows, and the row spacing is 2.2m. It uses 18 I-beams as columns, 18 I-beams as longitudinal beams, 18 I-beams as crossbeams, 18 I-beams and 18 I-beams as diagonal braces, and the outer side of the door frame column is horizontally reinforced with [12.6 channel steel; 4. Calculation of portal beam The area of ​​each grid of the top steel pipe is S1 = 0.75×2.2 = 1.65m 2 , loads for people, small machines, materials, etc. are 2.5KN / m 2 Calculation shows that the load borne by each vertical pole is F1=1.65×2.5=3.63KN; the load on the portal beam can be simplified to the calculation of three-span equal-span continuous beams subjected to concentrated loads, with the maximum span L =5.7m, and the concentrated force is the load borne by each vertical pole F1=3.63KN; Flexural strength calculation: ① Maximum bending moment M max = KMFL, KM—bending moment coefficient, look up the table to get 0.311; That is to say, M max = 0.311×3.63×1.73=1.95KN.m; ② Beam section strength σ = M max / W = 1.95 × 10 6 / (237×103)=8.23N / mm 2 <[f]= 215N / mm2, bending strength meets the requirements; 2) Shear strength calculation: ① Maximum shear force V max = KvF, from the table, Kv = 1.311; That is, V max = K vF 9 = 1.311 × 3.63 = 4.76 KN; ② Shear strength of beam section τ = V max × Sx / (Ix × tw) = 4.76 × 10 3 ×136.1×10 3 / (2370×10 4 ×7)=3.9N / mm2<[fv]=125N / mm 2 , Shear strength meets the requirements; 3) Deflection deformation check: ω=KW F 9L s / (100×E×Ix), from the table we get KW = 2.716; That is, ω = 2.716 × 3.63 × 1.73 3 / (100×2.06×10 8 ×2370×10 -8 )=0.105×10-3 m=0.105mm; ω=0.105mm<[ω]= L / 400=5700 / 400=14.25mm, L—span; the force deflection deformation meets the requirements; 4) Beam stability check: Beam slenderness ratio λ = h / ix = (4.432+1.2×2) / 8.15×10 -2 =84, from the table we get φ=0.661, N =ψ×A×f, that is, f=N / (ψ×A)= F1 / (ψ×A)3.63×103 / (0.661×35.5×100)=1.55N / mm2<[f]=215N / mm 2 , The stability of the portal beam meets the requirements; Force check calculation of portal frame columns and diagonal braces: The area of ​​each grid of the top steel pipe is S1 = 0.75 × 2.2 = 1.65m 2 , Total weight of steel pipe rack F2=20.6 KN; Beam weight F3 = (6.8 × 27.9 × 6 × 9.8 / 1000) × 1.2 = 11.2 KN × 1.2 = 13.44 KN; The weight of the longitudinal beam F4 = (12 × 27.9 × 2 × 9.8 / 1000) × 1.2 = 6.6KN × 1.2 = 7.92KN; the force borne by each column F4 = (S1 × 6.357 × 6.6 + F2 + F3 + F4) / (3 × 3); F4= (1.65×6.357×6.6+20.6+13.44+7.92) / (3×3)=12.57KN, the force on the diagonal brace; F5=12.57 / COS25=12.7KN; Stability check of steel brace in project 18: Column slenderness ratio λ = uL / ix,u = 1,L1 = 2.73m; λ=1×2.73 / (5.76×10 -2 ) = 47, and then we can get: φ=0.924, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.924×21.5×100)=6.4N / mm2<[f]=215N / mm 2 , stability meets the requirements; Stability check of steel brace in project 18: Column slenderness ratio λ = uL / ix,u = 1,L2 = 2.88m; λ=1×2.88 / (6.58×10 -2 ) = 44, and we can get from the table: φ=0.932, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.932×26.1×100)=5.3N / mm 2 <[f]=215N / mm 2 , stability meets the requirements; Conclusion: The loads on the trolley door frame columns and diagonal braces meet the requirements; Through the above analysis and calculation, it can be seen that the strength and rigidity of the entire test bench are sufficient; 5. Tunnel body advance support Advanced long pipe shed construction, advanced small pipe construction, and advanced mortar anchor bolt construction at the tunnel entrance; 6. Anchor construction The initial support anchor rods of the tunnel adopt A25 hollow grouting anchor rods, and the middle partition wall adopts A22 anchor rods, which are arranged in a plum blossom shape along the excavation surface; the hollow grouting anchor rods are constructed by trolley drilling, and the rock debris in the hole is blown away with high-pressure air, and the hollow anchor rod with the anchor head installed is inserted into the drilled hole; the grouting plug, pad and nut are installed at the tail end of the anchor rod, and the tail end of the anchor rod is connected to the selected grouting machine through a quick grouting joint; the grouting can be stopped when the cement slurry reaches the designed pressure value or the designed injection slurry volume; 7. Hanging of steel mesh The steel mesh is pre-processed and formed in the steel component factory outside the hole according to the design; the steel mesh is laid according to the actual undulation of the initial sprayed concrete surface, and the gap with the sprayed surface is 3cm; the steel mesh is spot welded with the steel mesh, the steel mesh and the anchor rod, and the steel mesh and the steel frame connecting bar to prevent the steel mesh from shaking during spraying; the steel mesh is processed into pieces in the component processing factory and welded into a whole in the hole. Before the steel mesh is made, the steel bars are straightened, rusted and degreased; 8. Steel frame production and installation The tunnel project is supported by steel frames. The steel frames are pre-processed and formed by an arch bending machine in the factory of structural parts outside the tunnel according to the design, and trial assembly is carried out. After meeting the design size, they are mass-produced and connected into a whole with bolts in the tunnel during construction. The installation in the tunnel is carried out after the initial spraying of concrete, and the positioning bars are welded. Longitudinal connecting bars are set between the steel frames, and the gaps between the steel frames are filled with sprayed concrete. 9. Shotcrete construction (1) Material innovation High Performance Concrete: 1) Mix ratio optimization: Experimental design: Based on the existing mix ratio, design multiple test schemes with different mix ratios, including cement dosage, water-cement ratio, aggregate ratio, etc. Material selection: Select high-quality cement, fine aggregate and coarse aggregate to ensure the quality of basic materials; Incorporation of high performance materials: Silica fume: Added in a certain proportion, its high activity can be used to improve the early strength and durability of concrete; Fly ash: As an admixture, it improves the workability and later strength of concrete; Steel fiber: added according to design requirements to enhance the toughness and crack resistance of concrete; Test verification: Through laboratory tests, test the strength, toughness, durability and other performance indicators of each mix ratio and select the optimal mix ratio; 2) Liquid accelerator research and development: Goal setting: clarify the performance requirements of accelerators, such as low dosage, good accelerating effect, strong stability, etc.; Formula research and development: Develop low-dosage potassium salt liquid accelerator and alkali-free high-efficiency liquid accelerator, and verify their performance through experiments; Performance testing: Conduct performance tests on the developed accelerating agent, such as concrete setting time, strength development, and stability; On-site application: Conduct on-site tests during tunnel construction and adjust the dosage and formula of the accelerating agent according to the actual results; New admixture Admixture selection and development: Market research: Research new admixtures available on the market, such as high-efficiency mineral viscosity enhancers (ST powder), etc. Performance evaluation: Evaluate the performance of the selected admixtures, including the effects of reducing rebound, improving strength, increasing density, and reducing permeability; Formula optimization: Based on the evaluation results, the formula of the admixture is optimized to achieve the best effect; Application test: Laboratory test: Under laboratory conditions, the optimized admixture is added to the shotcrete to test its performance changes; Field test: Conduct shotcrete test at the tunnel construction site to observe the effect of admixtures on rebound, strength, compactness, permeability, etc.; Effect evaluation: Based on the test results, evaluate the application effect of admixtures and make necessary adjustments; (2) Process optimization The construction method of combining dry spraying and wet spraying is adopted to reduce the rebound rate, improve the strength of concrete, reduce dust pollution and improve the working environment of workers; by optimizing the parameters such as the amount of pre-added water to aggregates and the amount of cement added, the good fluidity and sprayability of the concrete slurry can be achieved; Adopt multi-layer thin-layer spraying technology to replace one-time full-thickness spraying to improve the uniformity and density of shotcrete; especially in the tunnel arch top, control the thickness of the initial spraying layer to avoid the spraying layer from falling due to excessive thickness, which will affect the bonding effect of the shotcrete; 10. Drainage and waterproofing construction For the tunnel section passing through the fractured zone, it is expected that the groundwater is large. When drainage is adopted as the main method, which may affect the ecological environment, the principle of "blocking as the main method and limited discharge" is adopted according to the actual situation to achieve the purpose of effective water blocking, reliable waterproofing and economic rationality; 11. Tunnel ventilation The construction ventilation from the tunnel entrance to the tunnel adopts push-in ventilation; a ventilator is arranged on the right side of each tunnel entrance, and the ventilation pipe adopts a hose with a diameter of 1200mm; the ventilation hose is installed in the tunnel arch.

[0014] The beneficial effects of the present invention are as follows: It can be seen from the above technical solution that the present application provides a comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM, which has the following advantages: 1. Through the deep integration of BIM, VR, GIS and other technologies, the advancement and advantages of tunnel construction have been significantly improved. The BIM model accurately constructs the tunnel and the surrounding environment to achieve comprehensive information integration; VR technology simulates real construction scenes to improve predictive capabilities; GIS technology helps with precise planning and migration. The intelligent monitoring system monitors construction progress and environmental impacts in real time, and the early warning alarm mechanism ensures safety. These methods are particularly aimed at problems such as shallow tunnel construction that is easily affected by surface activities and large interference from the surrounding environment, providing effective means of fine control, safety assurance and environmental impact assessment, thereby reducing the difficulty and complexity of construction and improving construction efficiency and safety.

[0015] 2. The hybrid tunnel boring machine is flexibly adjusted according to geological conditions to ensure efficient rock breaking while reducing tool wear, and maintains optimal tunneling efficiency through real-time monitoring and performance adjustment. The application of electronic control systems is refined to achieve accurate parameter monitoring, remote monitoring and rapid fault diagnosis, and improve the level of intelligent equipment management. Data analysis supports decision optimization, and system upgrades and maintenance ensure stable operation. Overall, these methods effectively respond to the impact of surface activities, environmental issues and construction control challenges, improve construction safety, efficiency and quality control levels, and provide advanced solutions for tunnel construction under complex geological conditions.

[0016] 3. The measurement and control work of tunnel construction showed a high degree of professionalism. Through the fine division of CPI basic network and line network encryption, dual-frequency static receivers and digital levels were used to ensure high accuracy and comprehensive coverage. The strategy of encrypting leveling points and multiple re-measurements, especially increasing the number of measurements 50 meters before the tunnel was broken through, significantly improved the continuity and reliability of the measurement. At the same time, intelligent automatic data collection was used to replace manual recording, observation and calculation, and computer processing was fully realized, which greatly reduced labor intensity, eliminated manual errors, ensured that the observation results were accurate and reliable, and met the engineering precision requirements. These comprehensive measures provided solid technical support for tunnel construction and ensured the efficient and high-quality completion of the project.

[0017] 4. Through the optimization of high-performance concrete mix ratio and the development of new admixtures, the strength, toughness and durability of concrete are improved, while the rebound rate and permeability are reduced, ensuring the construction quality. In terms of process optimization, the combination of dry spraying and wet spraying reduces dust pollution, and the multi-layer thin-layer spraying technology improves the uniformity and density of sprayed concrete, especially in the tunnel arch position, effectively controlling the thickness of the initial spraying layer and avoiding the fall of the spraying layer. These innovative measures not only improve the working environment of workers, but also improve construction efficiency and project quality, showing a high level of technology and practical value.

[0018] 5. In view of the difficulties in the construction of shallow tunnels, the use of advanced geological prediction methods has shown significant advantages. This method combines geological, geophysical and drilling technologies to achieve accurate prediction and effectively avoid risks such as ground subsidence and collapse. The application of geological radar and ultrasonic detection has improved the accuracy of identifying adverse geological and groundwater conditions, facilitating timely warning and taking countermeasures. Advanced horizontal drilling further verifies the geophysical results to ensure construction safety. The combined use of these methods has significantly improved the safety and efficiency of tunnel construction and reduced the impact on the surrounding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a construction flow chart.

[0020] Figure 2 This is a schematic diagram of advanced horizontal drilling.

[0021] Figure 3 This is the cross-sectional diagram of CD method construction.

[0022] Figure 4 To reserve the cross-section diagram for core soil excavation.

[0023] Figure 5 This is the cross-sectional view of the step method.

[0024] Figure 6This is a schematic diagram of the cross section of the small duct for advance grouting.

[0025] Figure 7 This is the process flow chart for the advanced small duct construction.

[0026] Figure 8 Schematic diagram of the arrangement of advance mortar anchor rods.

[0027] Fig. 9 for Figure 8 Schematic diagram of II.

[0028] Fig.10 This is the process flow chart for the initial support construction of the tunnel.

[0029] Fig.11 This is a schematic diagram of push-in ventilation. Fig.12 This is a schematic diagram of the portal beam inspection. DETAILED DESCRIPTION

[0030] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments in the embodiments of the present application are within the scope of protection requested by the present application. like Figure 1 As shown: A comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM. The operation steps are as follows: 1. Deep integration and application of BIM, VR, GIS and other technologies: BIM model construction, VR environment construction, digital migration planning, intelligent monitoring system 2. Measurement and positioning: re-survey and encryption of tunnel plane control network, elevation control measurement, hole entry measurement, construction layout measurement, tunnel penetration measurement 3. Advanced geological forecast: application of geological radar, ultrasonic detection, advanced horizontal drilling, such as Figure 2 As shown; 4. Drainage and waterproofing construction at the cave entrance: Adopt the principle of "combining prevention, drainage, blocking and interception, taking measures according to local conditions and comprehensive management" to carry out waterproofing construction; 5. Construction of tunnel entrance section; 6. Tunnel excavation and initial support: follow the principle of "short advance, weak blasting, strong support, less disturbance, fast closure, frequent measurement", strictly control over-excavation and under-excavation, and initial support closely follows excavation. Including: CD excavation, reserved core soil excavation, step excavation method, advanced long pipe shed at the tunnel entrance, advanced small pipe, advanced mortar anchor, steel mesh spraying, steel frame production and shotcrete, etc.; Figure 3 , 4 , 5, 6, 7, 8, and 9.

[0031] 7. Monitoring and measurement; 8. Secondary lining construction: 9. Cable trough and ditch construction; 10. Construction of road surface inside the tunnel; 11. Construction of traffic safety and electromechanical engineering.

[0032] The specific construction method is: 1. Deep integration and application of BIM, VR, GIS and other technologies 1. Preliminary preparation (1) Project approval and survey and design (2) BIM model construction: Using BIM technology, a three-dimensional BIM model of the tunnel is constructed based on geological survey data and other design information. The model should include all key information such as tunnel structure, support system, excavation method, drainage system, etc.

[0033] (3) VR environment construction: Based on the BIM model, VR technology is used to build a virtual reality construction environment. This environment should simulate the tunnel construction scene as realistically as possible, including geological conditions, construction equipment, personnel configuration, etc.

[0034] 2. Digital migration planning (1) Data collection and collation: Conduct a comprehensive on-site survey of housing, communication cables, power cables, pipelines, etc. around the tunnel entrance to collect relevant information such as location, size, material, etc. Obtain basic information such as topographic maps, geological maps, and planning maps of the tunnel area to ensure the accuracy and completeness of the data.

[0035] (2) 3D modeling: Using GIS technology, the collected data is imported into the GIS platform for spatial analysis and processing to generate a 3D terrain model around the tunnel entrance. Combined with BIM technology, accurate 3D modeling of structures such as housing, communication cables, power cables, and pipelines is performed, including their geometric shapes, attribute information, etc.

[0036] (3) Digital migration planning: In the 3D model, the migration path is planned and optimized according to the tunnel construction requirements and the actual conditions of the surrounding structures. Considering factors such as time, cost, and safety during the migration process, a detailed migration plan and scheme is formulated. The simulation function of GIS is used to rehearse the migration process and verify the feasibility and rationality of the migration scheme.

[0037] (4) Plan review and adjustment: Organize experts to review the digital migration plan and put forward modification opinions and suggestions. Based on the review results, adjust and optimize the migration plan to ensure the feasibility and cost-effectiveness of the plan.

[0038] 3. Intelligent monitoring system (1) System design and development: Design the architecture and functional modules of the intelligent monitoring system according to the requirements of the migration plan. Develop the software platform of the intelligent monitoring system to realize functions such as data collection, processing, analysis and display.

[0039] (2) Monitoring equipment layout and installation: Place monitoring equipment such as cameras and sensors along the migration path and in key locations around the site. Ensure the stability and reliability of the monitoring equipment and conduct regular inspections and maintenance.

[0040] (3) Real-time monitoring and data analysis: Use the intelligent monitoring system to monitor the migration progress and surrounding environmental impact in real time, including the displacement, deformation, and damage of the structures. Process and analyze the monitoring data to generate a migration progress report and a surrounding environmental impact assessment report.

[0041] (4) Early warning and alarm mechanism: Set early warning and alarm thresholds. When the monitoring data exceeds the threshold, the system automatically issues an early warning or alarm signal. Relevant personnel are notified in a timely manner to take corresponding measures to ensure the safety and smooth progress of the migration work.

[0042] (5) System maintenance and upgrade: Regularly maintain and upgrade the intelligent monitoring system to ensure the stability and accuracy of the system. Continuously optimize and expand the system's functions and application scope based on actual needs and technological development.

[0043] 2. Measurement and positioning: 1. Re-survey and encryption of the plane control network of this tunnel (1) Re-survey of the basic plane control network (CPⅠ) and encryption of the line plane control network (CPⅡ). After the handover piles are completed, the surveying personnel shall be immediately organized to carry out the re-survey of the plane control network.

[0044] (2) The plane control network of the tunnel is the basic plane control network (CPⅠ), which is provided by the design unit and requires high measurement accuracy. The basic plane control network (CPⅠ) is usually measured by GPS Class B. After the control points are handed over, a measurement plan is formulated based on the handover data of the design unit, and all CPⅠ control points are re-measured with the same accuracy using a dual-frequency static receiver. Various tolerances and accuracy requirements (based on this) should meet the requirements of the Technical Specifications for Construction Measurement of Highway Tunnel Construction.

[0045] (3) After the resurvey of CPI control points is completed, the field observation records, original observation data, original data submitted by the design institute, and resurvey accuracy analysis and technical reports shall be reported or saved. The CPI control network adopts the baseline double difference fixed solution to perform three-dimensional unconstrained adjustment. CPII encryption should be combined with CPI to form a supporting network, and constrained adjustment and coordinate transformation should be performed through the CPI control network of the joint survey.

[0046] 2. Elevation control measurement: ①Re-survey of leveling points ②Encryption of the leveling network 3. Hole measurement The construction control points are set up through the layout of approach traverses and approach leveling routes to establish entry points, and then the plane and elevation control points are introduced into the tunnel through the entry points to provide underground plane and elevation basis for tunnel excavation. The near-entrance point should be in line of sight with the GPS point or precision traverse point, and the orientation should have the most favorable graphics. The approach traverse measurement is carried out with a 2″ or higher level total station according to the requirements of the first-level traverse.

[0047] 4. Construction layout measurement The three-dimensional polar coordinate method is used for surveying. In order to strengthen the verification conditions of the layout points, two other known traverse points can be used as the starting data, and the same method can be used to check whether the layout points are correct, or the coordinate measurement function of the total station can be used to measure the coordinates of the layout points with two other known traverse points.

[0048] 5. Tunnel penetration measurement The number of construction measurements should be increased about 50 meters before the tunnel is completed, and the entire line of the control wire should be re-measured until the tunnel is completed. After the tunnel is completed, the horizontal penetration error, longitudinal penetration error and elevation penetration error should be measured.

[0049] 3. Advanced geological forecast 1. Principle: According to the actual conditions of the tunnel project line length, geological conditions, etc., adhere to the principle of "three combinations" of advanced geological prediction and risk target section division, that is, "combination of geology with geophysical exploration and drilling, combination of inside and outside the tunnel, and combination of length and different geophysical exploration methods". On the basis of tunnel risk classification, adopt the corresponding prediction plan.

[0050] 2. Application of geological radar 1) Use geological radar (GPR) for short-term forecasts at a close distance (30-50m). Calibrate the geological radar before use, including equipment performance testing and parameter setting verification, to ensure data accuracy.

[0051] 2) Detection plan formulation: According to the tunnel construction progress and geological survey data, formulate a geological radar detection plan, clarify the detection area, detection frequency and detection time. Consider factors such as tunnel excavation direction and cross-section size to determine the layout and scanning path of the geological radar.

[0052] 3) When it is speculated that the tunnel may have other unfavorable geological conditions such as water-rich areas in synclines and fault fracture zones, advanced horizontal drilling is generally carried out 10 to 20 meters in advance.

[0053] 4) On-site detection operation: Arrange the geological radar on the tunnel excavation face or the working face, and ensure that it is parallel or perpendicular to the tunnel axis to obtain comprehensive geological information. Scan according to the detection plan, pay attention to controlling the scanning speed and distance, and avoid missing or repeated scanning.

[0054] 5) Data processing and interpretation: Collect geological radar detection data, use professional software to process and analyze data, and generate geological radar images. According to the image features, identify geological anomalies such as faults and karst caves ahead of tunnel excavation, and determine their location, scale and nature.

[0055] 6) Early warning and response measures: According to the geological radar detection results, timely issue geological anomaly warnings to remind construction personnel to pay attention to safety. According to the detected geological anomalies, formulate corresponding response measures, such as adjusting the construction plan, strengthening support measures, etc.

[0056] 3. Ultrasonic detection application 1) Equipment selection and layout: Select ultrasonic detection equipment suitable for the geological conditions of the tunnel to ensure that its detection range and accuracy meet the construction requirements. Arrange ultrasonic detectors on the tunnel excavation face or face to ensure that they are parallel or perpendicular to the tunnel axis in order to obtain accurate groundwater information.

[0057] 2) Detection parameter setting: According to the tunnel geological conditions and construction requirements, set the parameters of the ultrasonic detector, such as transmission frequency, receiving sensitivity, etc. Consider the flow rate and direction of groundwater and other factors to determine the scanning mode and time interval of ultrasonic detection.

[0058] 3) On-site detection and recording: Perform ultrasonic detection according to the detection plan, pay attention to controlling the detection distance and angle, and avoid interference and errors. Record the detection results, including ultrasonic propagation time, echo intensity and other parameters, to provide a basis for subsequent data analysis.

[0059] 4) Data processing and analysis: Use professional software to process and analyze ultrasonic detection data to generate images or reports on groundwater distribution and flow. Based on the analysis results, determine the distribution range, flow rate, flow direction and other characteristics of groundwater around the tunnel.

[0060] 5) Drainage and waterproofing measures: According to the results of ultrasonic detection, formulate corresponding drainage and waterproofing measures, such as setting up drainage ditches, installing waterproof curtains, etc. During the construction process, pay close attention to the changes in groundwater, and adjust drainage and waterproofing measures in time to ensure construction safety.

[0061] 4. Advanced horizontal drilling When the geological radar predicts that the surrounding rock ahead has poor geology, advance horizontal drilling is used in front. The advance drilling distance is generally 30m, with an overlap of 5m to ensure that there are enough safe rock pillars. The drilling equipment uses a down-the-hole drill or a geological drill. Advance drilling is arranged in sections with geophysical anomalies, sections with poor geological bodies in the design, complex sections where the geological conditions need to be further explored, and other sections with the danger of sudden water and mud. In general sections, a 30m exploration hole is drilled in the middle of the face, perpendicular to the face. In key sections, 3 to 5 30m exploration holes are drilled perpendicular to or outwardly to the face. The specific outward angle is determined based on the on-site forecast and geological data analysis.

[0062] like Fig.10 As shown: 4. Tunnel Construction The tunnel follows the guiding ideology of "comprehensive planning, balanced production, priority focus, segmented organization, highlighting difficulties, and orderly advancement". The tunnel is excavated from a single entrance and constructed from the entrance to the exit. The open tunnel and portal are constructed using the open excavation method, and the blind tunnel section is constructed using the step method, reserved core soil method, and CD method.

[0063] 1. Overall construction sequence of the tunnel: construction preparation → construction of tunnel entrance drainage system → construction of tunnel entrance section → tunnel body excavation and initial support → monitoring and measurement → secondary lining → cable trough and ditch construction → road surface inside the tunnel → traffic safety and electromechanical engineering construction; 2. Tunnel excavation (1) Mixed tunneling 1) Equipment selection and design: According to the tunnel geological survey report, clarify the distribution of strata along the tunnel, especially the alternation of hard rock and soft rock. Select a hybrid tunnel boring machine with the ability to tunnel hard and soft rocks, and ensure that its design parameters (such as cutterhead diameter, motor power, propulsion force, etc.) meet the needs of tunnel construction. Communicate with equipment suppliers to carry out customized design according to the specific conditions of the tunnel, such as the configuration of cutterhead tools and the optimization of rock breaking methods.

[0064] 2) Operation mode switching: During the excavation process, according to the lithology of the current excavation stratum, the machine control panel or remote control system can be used to flexibly switch to the appropriate working mode. In the hard rock mode, the cutter head speed and thrust are increased, and sharper cutters are used to efficiently break the rock; in the soft rock mode, the speed and thrust are appropriately reduced to reduce cutter wear and energy consumption.

[0065] 3) Performance monitoring and adjustment: Use the sensors on the tunnel boring machine to monitor key parameters such as tunneling speed, cutterhead wear, and motor temperature in real time. According to the monitoring data, timely adjust tunneling parameters such as tunneling speed and thrust distribution to maintain optimal tunneling efficiency.

[0066] 4) Maintenance and care: Develop a detailed maintenance and care plan for the tunnel boring machine, including regular inspection of tool wear, replacement of damaged parts, cleaning of the cooling system, etc. In the formations where hard and soft rocks alternate, pay special attention to the wear of the tools and replace severely worn tools in a timely manner to avoid affecting the tunneling efficiency and equipment life.

[0067] (2) Application refinement of electronic control systems 1) Parameter monitoring: Install and configure the electronic control system of the roadheader to ensure real-time monitoring of key parameters such as cutter head speed, thrust, torque, oil temperature, water pressure, etc. Set parameter alarm thresholds. When the parameters exceed the set range, the system automatically alarms and prompts the operator to take corresponding measures.

[0068] 2) Remote monitoring and diagnosis: Establish a remote monitoring center to transmit the data of the tunnel boring machine to the monitoring center in real time via a wireless network. Set up professional software in the monitoring center to analyze the data of the tunnel boring machine in real time and predict potential fault points.

[0069] When a tunnel boring machine breaks down, the remote diagnosis system can be used to quickly locate the cause of the failure, provide remote technical support or guide on-site repairs.

[0070] 3) Data management and analysis: Regularly back up and store the operation data of the tunnel boring machine and establish a tunnel boring machine operation database. Use data analysis tools to conduct in-depth analysis of data such as tunneling efficiency, energy consumption, and tool wear to provide decision support for tunnel boring machine performance optimization and construction management.

[0071] 4) System upgrade and maintenance: Regularly upgrade the software of the electronic control system to ensure the latest and stability of the system functions. Regularly maintain the system, including checking sensors, line connections, controllers, etc., to ensure the normal operation of the system.

[0072] 3. Tunnel excavation bench composition Door frame assembly: The door frame is a door-shaped platform made of welded steel of different specifications, with a total of 3 rows, and the row spacing is 2.2m. It uses 18 I-beams as columns, 18 I-beams as longitudinal beams, 18 I-beams as cross beams, 18 I-beams and 18 I-beams as diagonal braces, and the outer side of the door frame column is reinforced horizontally with [12.6 channel steel.

[0073] 4. Check and calculate the portal beam The area of ​​each grid of the top steel pipe is S1 = 0.75×2.2 = 1.65m 2 , loads for people, small machines, materials, etc. are 2.5KN / m 2Calculation shows that the load on each vertical pole is F1=1.65×2.5=3.63KN. The load on the portal beam can be simplified to the calculation of a three-span continuous beam with concentrated load, with the maximum span L =5.7m, and the concentrated force is the load on each vertical pole F1=3.63KN.

[0074] Flexural strength calculation ① Maximum bending moment M max = KMFL, KM—bending moment coefficient, look up the table to get 0.311; That is to say, M max = 0.311×3.63×1.73=1.95KN .m ② Beam section strength σ = M max / W = 1.95 × 10 6 / (237×103)=8.23N / mm 2 <[f]= 215N / mm2, bending strength meets the requirements! 2) Shear strength calculation ① Maximum shear force V max = KvF, from the table, Kv = 1.311; That is, V max = K vF 9 = 1.311 × 3.63 = 4.76 KN ② Shear strength of beam section τ = V max × Sx / (Ix × tw) = 4.76 × 10 3 ×136.1×10 3 / (2370×10 4 ×7)=3.9N / mm2<[fv]=125N / mm 2 , Shear strength meets the requirements! 3) Deflection deformation check ω=KW F 9L s / (100×E×Ix), from the table we get KW = 2.716 That is, ω = 2.716 × 3.63 × 1.73 3 / (100×2.06×10 8 ×2370×10 -8 )=0.105×10 -3 m=0.105mm ω=0.105mm<[ω]= L / 400=5700 / 400=14.25mm, L—span; the force deflection deformation meets the requirements! 4) Beam stability check Beam slenderness ratio λ = h / ix = (4.432+1.2×2) / 8.15×10 -2=84, from the table we get φ=0.661, N =ψ×A×f, that is, f=N / (ψ×A)= F1 / (ψ×A)3.63×103 / (0.661×35.5×100)=1.55N / mm2<[f]=215N / mm 2 , The stability of the portal beam meets the requirements! Check calculation of portal frame columns and diagonal braces The area of ​​each grid of the top steel pipe is S1 = 0.75 × 2.2 = 1.65m 2 , The total weight of the steel pipe rack is F2 = 20.6 KN.

[0075] Beam weight F3 = (6.8 × 27.9 × 6 × 9.8 / 1000) × 1.2 = 11.2 KN × 1.2 = 13.44 KN; Longitudinal beam weight F4 = (12 × 27.9 × 2 × 9.8 / 1000) × 1.2 = 6.6KN × 1.2 = 7.92KN. The force F4 borne by each column = (S1×6.357×6.6+F2+F3+F4) / (3×3) F4 = (1.65×6.357×6.6+20.6+13.44+7.92) / (3×3)=12.57KN, the force on the diagonal brace F5=12.57 / COS25=12.7KN.

[0076] 18. Stability Check of Steel Diagonal Braces Column slenderness ratio λ= uL / ix,u= 1,L1= 2.73m; λ=1×2.73 / (5.76×10 -2 ) = 47, then we can get φ=0.924, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.924×21.5×100)=6.4N / mm2<[f]=215N / mm 2 , stability meets the requirements! 18. Stability Check of Steel Diagonal Braces Column slenderness ratio λ = uL / ix,u = 1,L2 = 2.88m; λ=1×2.88 / (6.58×10 -2 ) = 44, then we can get φ=0.932, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.932×26.1×100)=5.3N / mm 2<[f]=215N / mm 2 , stability meets the requirements! Conclusion: The load bearing capacity of the trolley door frame columns and diagonal braces meets the requirements! Through the above analysis and calculation, it can be seen that the strength and rigidity of the entire gantry are sufficient.

[0077] 4. Tunnel body advance support Advanced long pipe shed construction at the tunnel entrance, advanced small guide tube construction, and advanced mortar anchor rod construction.

[0078] 5. Anchor construction The initial support anchor rods of the tunnel adopt A25 hollow grouting anchor rods, and the middle partition wall adopts A22 anchor rods, which are arranged in a plum blossom shape along the excavation surface. The hollow grouting anchor rod construction adopts trolley drilling construction, and the rock debris in the hole is blown away with high-pressure wind, and the hollow anchor rod with the anchor head installed is inserted into the drill hole. The grouting plug, pad and nut are installed at the tail end of the anchor rod, and the tail end of the anchor rod is connected to the selected grouting machine through a quick grouting joint. When the cement slurry reaches the designed pressure value or the designed injection slurry volume, the grouting can be stopped.

[0079] 6. Hanging of steel mesh The steel mesh is pre-processed and formed in the steel component factory outside the hole according to the design. The steel mesh is laid according to the actual undulation of the initial sprayed concrete surface, and the gap with the sprayed surface is 3cm. The steel mesh is spot welded with the steel mesh, the steel mesh and the anchor rod, and the steel mesh and the steel frame connecting bar to prevent the steel mesh from shaking during spraying. The steel mesh is processed into pieces in the component processing factory and welded in the hole to form a whole. Before the steel mesh is made, the steel bars are straightened, rusted and degreased.

[0080] 7. Steel frame production and installation The tunnel project is supported by steel frame. The steel frame is pre-processed and formed by an arch bending machine in the factory of the structure outside the tunnel according to the design, and then assembled and mass-produced after meeting the design size. During construction, it is connected into a whole with bolts in the tunnel. The installation in the tunnel is carried out after the initial spraying of concrete, and welded with the positioning bars. Longitudinal connecting bars are set between the steel frames, and the gaps between the steel frames are filled with sprayed concrete. 8. Shotcrete construction (1) Material innovation High Performance Concrete: 1) Mix ratio optimization: Experimental design: Based on the existing mix proportions, design multiple groups of test schemes with different mix proportions, including cement dosage, water-cement ratio, aggregate ratio, etc.

[0081] Material selection: Select high-quality cement, fine aggregate and coarse aggregate to ensure the quality of basic materials.

[0082] Incorporation of high performance materials: Silica fume: Added in a certain proportion, its high activity is used to improve the early strength and durability of concrete.

[0083] Fly ash: As an admixture, it improves the workability and later strength of concrete.

[0084] Steel fiber: added according to design requirements to enhance the toughness and crack resistance of concrete.

[0085] Test verification: Through laboratory tests, the strength, toughness, durability and other performance indicators of each mix ratio are tested to select the optimal mix ratio.

[0086] 2) Liquid accelerator research and development: Goal setting: clarify the performance requirements of accelerators, such as low dosage, good accelerating effect, and strong stability.

[0087] Formula research and development: Develop low-dosage potassium salt liquid accelerator and alkali-free high-efficiency liquid accelerator, and verify their performance through experiments.

[0088] Performance testing: Conduct performance tests on the developed accelerating agent such as concrete setting time, strength development, and stability.

[0089] On-site application: Conduct on-site tests during tunnel construction and adjust the dosage and formula of the accelerating agent according to the actual results.

[0090] New admixture Admixture selection and development: Market research: Research new admixtures available in the market, such as high-efficiency mineral viscosity enhancers (ST powder), etc.

[0091] Performance evaluation: Evaluate the performance of the selected admixtures, including the effects of reducing rebound, improving strength, increasing density, and reducing permeability.

[0092] Formula optimization: Based on the evaluation results, the formula of the admixture is optimized to achieve the best effect.

[0093] Application test: Laboratory test: Under laboratory conditions, the optimized admixtures are added to shotcrete to test their performance changes.

[0094] Field test: Shotcrete test is carried out at the tunnel construction site to observe the effect of admixtures on rebound, strength, compactness, permeability, etc.

[0095] Effect evaluation: Based on the test results, evaluate the application effect of the admixture and make necessary adjustments.

[0096] Promotion and application: Technical training: Provide construction personnel with training on admixture usage techniques to ensure correct and efficient use.

[0097] Standardized management: Establish standardized processes and management systems for the use of admixtures to ensure the stability and reliability of construction quality.

[0098] Continuous monitoring: During the use of admixtures, continuously monitor their performance changes and impact on construction quality, and adjust the use strategy in a timely manner.

[0099] (2) Process optimization The construction method of combining dry spraying and wet spraying is adopted to reduce the rebound rate, improve the strength of concrete, reduce dust pollution and improve the working environment of workers. By optimizing the parameters such as the amount of pre-added water to the aggregate and the amount of cement, the good fluidity and sprayability of the concrete paste can be achieved.

[0100] Adopting multi-layer thin-layer spraying technology to replace one-time full-thickness spraying can improve the uniformity and density of shotcrete. Especially at the top of the tunnel vault, control the thickness of the initial spraying layer to avoid the spraying layer from falling due to excessive thickness, which will affect the bonding effect of the shotcrete.

[0101] 9. Drainage and drainage construction For the section where the tunnel passes through the fractured zone, it is expected that the groundwater level is high. When drainage is the main method and may affect the ecological environment, the principle of "blocking as the main method and limited discharge" is adopted according to the actual situation to achieve the goals of effective water blocking, reliable waterproofing and economic rationality.

[0102] 10. Tunnel ventilation like Fig.11 As shown: The construction ventilation from the tunnel entrance to the tunnel adopts the push-in ventilation. A ventilator is arranged on the right side of each tunnel entrance, and the ventilation pipe adopts a hose with a diameter of 1200mm. The ventilation hose is installed in the tunnel arch.

[0103] The above are only embodiments provided for the present application and are not intended to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A comprehensive construction method for shallow buried tunnels in residential areas and coastal tidal areas based on BIM, characterized in that It includes the following steps: Step 1: Deep integration and application of BIM, VR and GIS technologies; Step 2: Measurement and positioning; Step 3: Advanced geological forecast; Step 4: Tunnel construction; Tunnel construction includes: construction preparation, construction of tunnel entrance drainage system, tunnel entrance section construction, tunnel body excavation and initial support, monitoring and measurement, secondary lining, cable trough and ditch construction, tunnel pavement, and traffic safety and electromechanical engineering construction.

2. The comprehensive construction method of shallow buried tunnels in residential areas and coastal tidal areas based on BIM according to claim 1 is characterized in that Step one includes:

1. Preliminary preparation (1) Project approval and survey and design (2) BIM model construction: Using BIM technology, a three-dimensional BIM model of the tunnel is constructed based on geological survey data and other design information. The model should include all key information such as tunnel structure, support system, excavation method, drainage system, etc. (3) VR environment construction: Based on the BIM model, VR technology is used to build a virtual reality construction environment. This environment should simulate the tunnel construction scene as realistically as possible, including geological conditions, construction equipment, personnel configuration, etc.

2. Digital migration planning (1) Data collection and collation: Conduct a comprehensive on-site survey of housing, communication cables, power cables, pipelines, etc. around the tunnel entrance to collect relevant information such as location, size, material, etc.; obtain basic information such as topographic maps, geological maps, and planning maps of the tunnel area to ensure the accuracy and completeness of the data; (2) 3D modeling: Using GIS technology, the collected data is imported into the GIS platform for spatial analysis and processing to generate a 3D terrain model around the tunnel entrance. Combined with BIM technology, accurate 3D modeling of structures such as housing, communication cables, power cables, and pipelines is performed, including their geometric shapes, attribute information, etc. (3) Digital migration planning: In the 3D model, the migration path is planned and optimized according to the actual conditions of the tunnel construction and surrounding structures. Considering factors such as time, cost, and safety during the migration process, a detailed migration plan and scheme is formulated. The simulation function of GIS is used to rehearse the migration process and verify the feasibility and rationality of the migration scheme. (4) Plan review and adjustment: Organize experts to review the digital migration plan and put forward modification opinions and suggestions; adjust and optimize the migration plan based on the review results to ensure the feasibility and cost-effectiveness of the plan; 3. Intelligent monitoring system (1) System design and development: Design the architecture and functional modules of the intelligent monitoring system according to the requirements of the migration plan; develop the software platform of the intelligent monitoring system to realize functions such as data collection, processing, analysis and display; (2) Layout and installation of monitoring equipment: Layout monitoring equipment such as cameras and sensors along the migration path and in key locations around the area; ensure the stability and reliability of the monitoring equipment and conduct regular inspections and maintenance; (3) Real-time monitoring and data analysis: Using intelligent monitoring systems to monitor the progress of migration and the impact on the surrounding environment in real time, including the displacement, deformation, and damage of structures; processing and analyzing monitoring data to generate migration progress reports and surrounding environmental impact assessment reports; (4) Early warning and alarm mechanism: Set early warning and alarm thresholds. When the monitoring data exceeds the threshold, the system automatically issues an early warning or alarm signal; promptly notify relevant personnel to take corresponding measures to ensure the safety and smooth progress of the migration work; (5) System maintenance and upgrade: Regularly maintain and upgrade the intelligent monitoring system to ensure the stability and accuracy of the system; continuously optimize and expand the system's functions and application scope based on actual needs and technological development.

3. The comprehensive construction method of shallow buried tunnels in residential areas and coastal tidal areas based on BIM according to claim 1 is characterized in that Step 2 includes:

1. Re-survey and encryption of the plane control network of this tunnel (1) Re-survey of the basic plane control network (CPⅠ) and encryption of the line plane control network (CPⅡ); after the handover piles are completed, immediately organize surveyors to carry out re-survey of the plane control network; (2) The plane control network of the tunnel is the basic plane control network (CPⅠ), which is provided by the design unit and requires high measurement accuracy. The basic plane control network (CPⅠ) is usually measured by GPS Class B. After the control points are handed over, a measurement plan is formulated based on the handover data of the design unit, and all CPⅠ control points are re-measured with the same accuracy using a dual-frequency static receiver. Various tolerances and accuracy requirements (based on this) should meet the requirements of the Technical Specifications for Construction Surveying of Highway Tunnel Construction. (3) After the resurvey of CPI control points is completed, the field observation records, original observation data, original data submitted by the design institute, and resurvey accuracy analysis and technical reports shall be reported or saved; the CPI control network adopts the baseline double difference fixed solution to perform three-dimensional unconstrained adjustment; CPII encryption should be combined with CPI to form an auxiliary network, and constrained adjustment and coordinate transformation should be performed through the CPI control network of the joint survey; 2. Elevation control measurement: ①Re-survey of leveling points ②Encryption of the leveling network 3. Hole measurement The construction control points are set up through the layout of approach traverses and approach leveling routes to establish entry points, and then the plane and elevation control points are introduced into the tunnel through the entry points to provide underground plane and elevation basis for tunnel excavation; the point near the tunnel entrance is in line of sight with the GPS point or precision traverse point, and the orientation should have the most favorable graphics; the approach traverse measurement is carried out with a 2″ or higher level total station according to the requirements of the first level traverse; 4. Construction layout measurement The three-dimensional polar coordinate method is used for surveying. In order to strengthen the verification conditions of the stakeout points, two other known traverse points can be used as the starting data, and the same method can be used to check whether the stakeout points are correct, or the coordinate measurement function of the total station can be used to measure the coordinates of the stakeout points with two other known traverse points; 5. Tunnel penetration measurement About 50 meters before the tunnel is broken through, the number of construction measurements should be increased, and the entire line of the control wire should be re-surveyed until the tunnel is guaranteed to be broken through; after the tunnel is broken through, the lateral breakthrough error, longitudinal breakthrough error and elevation breakthrough error should be measured.

4. The comprehensive construction method of shallow buried tunnels in residential areas and coastal tidal areas based on BIM according to claim 1 is characterized in that Step three includes:

1. Principle: According to the actual situation of the tunnel project line length, geological conditions, etc., adhere to the principle of "three combinations" of advanced geological prediction and risk target section division, that is, "combination of geology with geophysical exploration and drilling, combination of inside and outside the tunnel, and combination of length and different geophysical exploration methods", and adopt the corresponding prediction plan based on the tunnel risk classification; 2. Application of geological radar 1) Use geological radar (GPR) to conduct short-range (30-50m) microscopic near-term forecasts. Before use, calibrate the geological radar, including equipment performance testing, parameter setting verification, etc., to ensure data accuracy; 2) Detection plan formulation: formulate a geological radar detection plan based on the tunnel construction progress and geological survey data, clarify the detection area, detection frequency and detection time; consider factors such as tunnel excavation direction and cross-section size to determine the layout and scanning path of the geological radar; 3) When it is speculated that the tunnel may have other unfavorable geological conditions such as water-rich areas, such as synclines, fault fracture zones, etc., advanced horizontal drilling is generally carried out 10 to 20 meters in advance; 4) On-site detection operation: Arrange the geological radar on the tunnel excavation face or working face, ensuring that it is parallel or perpendicular to the tunnel axis in order to obtain comprehensive geological information; scan according to the detection plan, pay attention to controlling the scanning speed and distance, and avoid missing or repeated scanning; 5) Data processing and interpretation: Collect geological radar detection data, use professional software to process and analyze data, and generate geological radar images; identify geological anomalies such as faults and karst caves ahead of tunnel excavation based on image features, and determine their location, scale and nature; 6) Early warning and response measures: Based on the geological radar detection results, timely issue geological anomaly warnings to remind construction personnel to pay attention to safety; formulate corresponding response measures for detected geological anomalies, such as adjusting the construction plan, strengthening support measures, etc.; 3. Ultrasonic detection application 1) Equipment selection and layout: Select ultrasonic detection equipment suitable for the geological conditions of the tunnel to ensure that its detection range and accuracy meet the construction requirements; arrange ultrasonic detectors on the tunnel excavation face or working face to ensure that they are parallel or perpendicular to the tunnel axis in order to obtain accurate groundwater information; 2) Detection parameter setting: according to the tunnel geological conditions and construction requirements, set the parameters of the ultrasonic detector, such as transmission frequency, receiving sensitivity, etc.; consider the flow rate and direction of groundwater and other factors to determine the scanning mode and time interval of ultrasonic detection; 3) On-site detection and recording: Conduct ultrasonic detection according to the detection plan, pay attention to controlling the detection distance and angle, and avoid interference and errors; record the detection results, including ultrasonic propagation time, echo intensity and other parameters, to provide a basis for subsequent data analysis; 4) Data processing and analysis: Use professional software to process and analyze ultrasonic detection data to generate images or reports of groundwater distribution and flow conditions; based on the analysis results, determine the distribution range, flow velocity, flow direction and other characteristics of groundwater around the tunnel; 5) Drainage and waterproofing measures: According to the ultrasonic detection results, formulate corresponding drainage and waterproofing measures, such as setting up drainage ditches and installing waterproof curtains, etc.; pay close attention to the changes in groundwater during the construction process, and adjust the drainage and waterproofing measures in time to ensure construction safety; 4. Advanced horizontal drilling When the geological radar predicts that the surrounding rock ahead has poor geology, advance horizontal drilling is adopted in front. The advance drilling distance is generally 30m, with an overlap of 5m to ensure that there are enough safe rock pillars. The drilling equipment uses a down-the-hole drill or a geological drill. The advance drilling is arranged in sections with geophysical anomalies, sections with poor geological bodies in the design, complex sections where the geological conditions need to be further explored, and other sections with the danger of sudden water and mud. In general sections, a 30m exploration hole perpendicular to the face is drilled in the middle of the face, and 3 to 5 30m exploration holes perpendicular to or inclined to the face are drilled in key sections. The specific outward angle is determined based on the on-site forecast and analysis of geological data.

5. The comprehensive construction method of shallow buried tunnels in residential areas and coastal tidal areas based on BIM according to claim 1 is characterized in that Step 4 includes: The tunnel follows the guiding ideology of "comprehensive planning, balanced production, priority, segmented organization, highlighting difficulties, and orderly advancement". The tunnel is excavated from a single entrance and constructed from the entrance to the exit. The open tunnel and portal are constructed using the open-cut method, and the blind tunnel section is constructed using the step method, reserved core soil method, and CD method.

1. Overall construction sequence of the tunnel: construction preparation → construction of tunnel entrance drainage system → construction of tunnel entrance section → tunnel body excavation and initial support → monitoring and measurement → secondary lining → cable trough and ditch construction → road surface inside the tunnel → traffic safety and electromechanical engineering construction; 2. Tunnel excavation (1) Mixed tunneling 1) Equipment selection and design: According to the tunnel geological survey report, clarify the distribution of strata along the tunnel, especially the alternation of hard rock and soft rock; select a hybrid tunnel boring machine with the ability to tunnel hard and soft rocks, and ensure that its design parameters (such as cutterhead diameter, motor power, propulsion force, etc.) meet the requirements of tunnel construction; communicate with equipment suppliers to carry out customized design according to the specific conditions of the tunnel, such as the configuration of cutterhead tools and the optimization of rock breaking methods; 2) Operation mode switching: During the excavation process, according to the lithology of the current excavation stratum, the machine can flexibly switch to the appropriate working mode through the control panel or remote control system of the tunnel boring machine. In the hard rock mode, the cutter head speed and thrust are increased, and sharper cutters are used to efficiently break the rock; in the soft rock mode, the speed and thrust are appropriately reduced to reduce cutter wear and energy consumption; 3) Performance monitoring and adjustment: Use the sensors on the tunnel boring machine to monitor key parameters such as tunneling speed, cutterhead wear, and motor temperature in real time; adjust tunneling parameters such as tunneling speed and thrust distribution in a timely manner based on the monitoring data to maintain optimal tunneling efficiency; 4) Maintenance and care: Develop a detailed maintenance and care plan for the tunnel boring machine, including regular inspection of tool wear, replacement of damaged parts, cleaning of the cooling system, etc.; in formations where hard and soft rocks alternate, pay special attention to tool wear and replace severely worn tools in a timely manner to avoid affecting tunneling efficiency and equipment life; (2) Application refinement of electronic control systems 1) Parameter monitoring: Install and configure the electronic control system of the roadheader to ensure real-time monitoring of key parameters such as cutter head speed, thrust, torque, oil temperature, and water pressure; set parameter alarm thresholds. When the parameters exceed the set range, the system automatically alarms and prompts the operator to take corresponding measures; 2) Remote monitoring and diagnosis: Establish a remote monitoring center to transmit the data of the roadheader to the monitoring center in real time via a wireless network; set up professional software in the monitoring center to analyze the data of the roadheader in real time and predict potential fault points; When a roadheader fails, the remote diagnosis system can be used to quickly locate the cause of the failure, provide remote technical support or guide on-site repairs; 3) Data management and analysis: Regularly back up and store the operation data of the roadheader and establish a roadheader operation database; use data analysis tools to conduct in-depth analysis of data such as tunneling efficiency, energy consumption, and tool wear to provide decision support for roadheader performance optimization and construction management; 4) System upgrade and maintenance: regularly upgrade the software of the electronic control system to ensure the latest and stability of the system functions; regularly maintain the system, including checking sensors, line connections, controllers, etc., to ensure the normal operation of the system; 3. Tunnel excavation rig composition Door frame assembly: The door frame is a door-shaped frame welded with steel of different specifications, with a total of 3 rows, and the row spacing is 2.2m. It uses 18 I-beams as columns, 18 I-beams as longitudinal beams, 18 I-beams as crossbeams, 18 I-beams and 18 I-beams as diagonal braces, and the outer side of the door frame column is horizontally reinforced with [12.6 channel steel; 4. Calculation of portal beam The area of ​​each grid of the top steel pipe is S1 = 0.75×2.2 = 1.65m 2 , loads for people, small machines, materials, etc. are 2.5KN / m 2 Calculation shows that the load borne by each vertical pole is F1=1.65×2.5=3.63KN; the load on the portal beam can be simplified to the calculation of three-span equal-span continuous beams subjected to concentrated loads, with the maximum span L =5.7m, and the concentrated force is the load borne by each vertical pole F1=3.63KN; Flexural strength calculation: ① Maximum bending moment M max = KMFL, KM—bending moment coefficient, look up the table to get 0.311; That is to say, M max = 0.311×3.63×1.73=1.95KN.m; ② Beam section strength σ = M max / W = 1.95 × 10 6 / (237×103)=8.23N / mm 2 <[f]= 215N / mm2, bending strength meets the requirements; 2) Shear strength calculation: ① Maximum shear force V max = KvF, from the table, Kv = 1.311; That is, V max = K vF 9 = 1.311 × 3.63 = 4.76 KN; ② Shear strength of beam section τ = V max × Sx / (Ix × tw) = 4.76 × 10 3 ×136.1×10 3 / (2370×10 4 ×7)=3.9N / mm2<[fv]=125N / mm 2 , Shear strength meets the requirements; 3) Deflection deformation check: ω=KW F 9L s / (100×E×Ix), from the table we get KW = 2.716; That is, ω = 2.716 × 3.63 × 1.73 3 / (100×2.06×10 8 ×2370×10 -8 )=0.105×10 -3 m=0.105mm; ω=0.105mm<[ω]= L / 400=5700 / 400=14.25mm, L—span; the force deflection deformation meets the requirements; 4) Beam stability check: Beam slenderness ratio λ = h / ix = (4.432+1.2×2) / 8.15×10 -2 =84, from the table we get φ=0.661, N =ψ×A×f, that is, f=N / (ψ×A)= F1 / (ψ×A)3.63×103 / (0.661×35.5×100)=1.55N / mm2<[f]=215N / mm 2 , The stability of the portal beam meets the requirements; Force check calculation of portal frame columns and diagonal braces: The area of ​​each grid of the top steel pipe is S1 = 0.75 × 2.2 = 1.65m 2 , Total weight of steel pipe rack F2=20.6 KN; Beam weight F3 = (6.8 × 27.9 × 6 × 9.8 / 1000) × 1.2 = 11.2 KN × 1.2 = 13.44 KN; The weight of the longitudinal beam F4 = (12 × 27.9 × 2 × 9.8 / 1000) × 1.2 = 6.6KN × 1.2 = 7.92KN; the force borne by each column F4 = (S1 × 6.357 × 6.6 + F2 + F3 + F4) / (3 × 3); F4= (1.65×6.357×6.6+20.6+13.44+7.92) / (3×3)=12.57KN, the force on the diagonal brace; F5=12.57 / COS25=12.7KN; Stability check of steel brace in project 18: Column slenderness ratio λ = uL / ix,u = 1,L1 = 2.73m; λ=1×2.73 / (5.76×10 -2 ) = 47, and then we can get: φ=0.924, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.924×21.5×100)=6.4N / mm2<[f]=215N / mm 2 , stability meets the requirements; Stability check of steel brace in project 18: Column slenderness ratio λ = uL / ix,u = 1,L2 = 2.88m; λ=1×2.88 / (6.58×10 -2 ) = 44, and we can get from the table: φ=0.932, N =ψ×A×f, that is, f= F5 / (ψ×A)=12.7×103 / (0.932×26.1×100)=5.3N / mm 2 <[f]=215N / mm 2 , stability meets the requirements; Conclusion: The loads on the trolley door frame columns and diagonal braces meet the requirements; Through the above analysis and calculation, it can be seen that the strength and rigidity of the entire test bench are sufficient; 5. Tunnel body advance support Advanced long pipe shed construction, advanced small pipe construction, and advanced mortar anchor bolt construction at the tunnel entrance; 6. Anchor construction The initial support anchor rods of the tunnel adopt A25 hollow grouting anchor rods, and the middle partition wall adopts A22 anchor rods, which are arranged in a plum blossom shape along the excavation surface; the hollow grouting anchor rods are constructed by trolley drilling, and the rock debris in the hole is blown away with high-pressure air, and the hollow anchor rod with the anchor head installed is inserted into the drilled hole; the grouting plug, pad and nut are installed at the tail end of the anchor rod, and the tail end of the anchor rod is connected to the selected grouting machine through a quick grouting joint; the grouting can be stopped when the cement slurry reaches the designed pressure value or the designed injection slurry volume; 7. Hanging of steel mesh The steel mesh is pre-processed and formed in the steel component factory outside the hole according to the design; the steel mesh is laid according to the actual undulation of the initial sprayed concrete surface, and the gap with the sprayed surface is 3cm; the steel mesh is spot welded with the steel mesh, the steel mesh and the anchor rod, and the steel mesh and the steel frame connecting bar to prevent the steel mesh from shaking during spraying; the steel mesh is processed into pieces in the component processing factory and welded into a whole in the hole. Before the steel mesh is made, the steel bars are straightened, rusted and degreased; 8. Steel frame production and installation The tunnel project is supported by steel frames. The steel frames are pre-processed and formed by an arch bending machine in the factory of structural parts outside the tunnel according to the design, and trial assembly is carried out. After meeting the design size, they are mass-produced and connected into a whole with bolts in the tunnel during construction. The installation in the tunnel is carried out after the initial spraying of concrete, and the positioning bars are welded. Longitudinal connecting bars are set between the steel frames, and the gaps between the steel frames are filled with sprayed concrete.

9. Shotcrete construction (1) Material innovation High Performance Concrete: 1) Mix ratio optimization: Experimental design: Based on the existing mix ratio, design multiple test schemes with different mix ratios, including cement dosage, water-cement ratio, aggregate ratio, etc. Material selection: Select high-quality cement, fine aggregate and coarse aggregate to ensure the quality of basic materials; Incorporation of high performance materials: Silica fume: Added in a certain proportion, its high activity can be used to improve the early strength and durability of concrete; Fly ash: As an admixture, it improves the workability and later strength of concrete; Steel fiber: added according to design requirements to enhance the toughness and crack resistance of concrete; Test verification: Through laboratory tests, test the strength, toughness, durability and other performance indicators of each mix ratio and select the optimal mix ratio; 2) Liquid accelerator research and development: Goal setting: clarify the performance requirements of accelerators, such as low dosage, good accelerating effect, strong stability, etc.; Formula research and development: Develop low-dosage potassium salt liquid accelerator and alkali-free high-efficiency liquid accelerator, and verify their performance through experiments; Performance testing: Conduct performance tests on the developed accelerating agent, such as concrete setting time, strength development, and stability; On-site application: Conduct on-site tests during tunnel construction and adjust the dosage and formula of the accelerating agent according to the actual results; New admixture Admixture selection and development: Market research: Research new admixtures available on the market, such as high-efficiency mineral viscosity enhancers (ST powder), etc. Performance evaluation: Evaluate the performance of the selected admixtures, including the effects of reducing rebound, improving strength, increasing density, and reducing permeability; Formula optimization: Based on the evaluation results, the formula of the admixture is optimized to achieve the best effect; Application test: Laboratory test: Under laboratory conditions, the optimized admixture is added to the shotcrete to test its performance changes; Field test: Conduct shotcrete test at the tunnel construction site to observe the effect of admixtures on rebound, strength, compactness, permeability, etc.; Effect evaluation: Based on the test results, evaluate the application effect of admixtures and make necessary adjustments; (2) Process optimization The construction method of combining dry spraying and wet spraying is adopted to reduce the rebound rate, improve the strength of concrete, reduce dust pollution and improve the working environment of workers; by optimizing the parameters such as the amount of pre-added water to aggregates and the amount of cement added, the good fluidity and sprayability of the concrete slurry can be achieved; Adopt multi-layer thin-layer spraying technology to replace one-time full-thickness spraying to improve the uniformity and density of shotcrete; especially in the tunnel arch top, control the thickness of the initial spraying layer to avoid the spraying layer from falling due to excessive thickness, which will affect the bonding effect of the shotcrete; 10. Drainage and waterproofing construction For the tunnel section passing through the fractured zone, it is expected that the groundwater is large. When drainage is adopted as the main method, it may affect the ecological environment. According to the actual situation, the principle of "blocking as the main method and limited discharge" is adopted to achieve the purpose of effective water blocking, reliable waterproofing and economic rationality; 11. Tunnel ventilation The construction ventilation from the tunnel entrance to the tunnel adopts push-in ventilation; a ventilator is arranged on the right side of each tunnel entrance, and the ventilation pipe adopts a hose with a diameter of 1200mm; the ventilation hose is installed in the tunnel arch.

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