Intelligent ventilation construction method for limited space construction of steel box girder

Abstract

The invention relates to an intelligent ventilation construction method for limited space construction of a steel box girder, which comprises the following steps: preparation before construction: establishing a three-dimensional model of the steel box girder by utilizing BIM software, simulating and optimizing a construction scheme based on the three-dimensional model, and determining the optimal layout and material requirements of ventilation equipment; ventilation equipment is arranged, specifically, the installation process of the ventilation equipment is simulated in the BIM model, the installation process comprises the positions and connection modes of an intelligent air opening, a ventilation pipeline, an air suction and exhaust fan and a sensor, and it is ensured that the layout of the ventilation equipment can cover the whole limited space; debugging a ventilation system; steel box girder limited space construction: a sensor feeds back the air quality, temperature and humidity in the limited space to a BIM ventilation system in real time, and the system automatically adjusts the operation state of ventilation equipment according to preset indexes; and cleaning after construction is completed. Ventilation equipment can be accurately arranged through the BIM technology, accurate control over the ventilation system is achieved, the ventilation efficiency is improved, energy consumption is reduced, and it is ensured that the air quality is stable.

Description

Technical Field

[0001] This invention belongs to the field of ventilation technology for steel box girders, specifically relating to an intelligent ventilation construction method for steel box girders in confined spaces. Background Technology

[0002] During the construction of steel box girders, welding, grinding, and painting operations must be carried out in enclosed or semi-enclosed confined spaces. These operations generate a large amount of welding fumes (containing heavy metal oxides such as manganese and chromium), grinding dust (such as iron filings and oxide scale), and volatile organic compounds (VOCs), resulting in a decrease in oxygen concentration and an excess of harmful gas concentrations (such as CO, NO2, and benzene compounds) in the space. This can easily lead to safety accidents such as asphyxiation, poisoning, and explosions. Long-term exposure may also induce chronic diseases such as pneumoconiosis and occupational asthma.

[0003] Traditional ventilation methods (such as direct blowing of axial flow fans and natural ventilation) have the following drawbacks: 1. Disordered airflow organization and inability to control the airflow path in a directional manner, resulting in the local accumulation of pollutants; 2. Due to spatial structure limitations, the ventilation effect in dead areas (such as the inner side of the web of the box girder and the gaps between stiffening ribs) is poor; 3. Lack of real-time monitoring, inability to dynamically adjust the air volume, and difficulty in responding to sudden pollution events.

[0004] To address the aforementioned issues, there is an urgent need to develop an intelligent, directional, and low-energy-consumption ventilation method. Through precise airflow control and real-time monitoring, this method can achieve efficient dilution and discharge of pollutants within a confined space, fundamentally ensuring the health and safety of workers. Summary of the Invention

[0005] To achieve the above objectives, this invention provides an intelligent ventilation construction method for steel box girder construction in confined spaces.

[0006] The specific technical solution is as follows: A smart ventilation construction method for steel box girder construction in confined spaces includes the following steps: (1) Pre-construction preparation: Use BIM software to build a three-dimensional model of the steel box girder (including internal structure, spatial layout, etc.), simulate and optimize the construction plan based on the three-dimensional model, and determine the optimal layout and material requirements of the ventilation equipment; at the same time, combine the on-site survey data to update the three-dimensional model and improve the accuracy of the construction plan. (2) Ventilation equipment setup: Simulate the installation process of ventilation equipment in the BIM model, including the location and connection method of intelligent air outlets, ventilation ducts, exhaust fans, and multi-functional monitoring sensors, to ensure that the layout of ventilation equipment can cover the entire limited space; at the same time, accurately mark the location of human passages and air vents in the BIM model to ensure that these structures are correctly reserved during construction; install the ventilation equipment according to the model simulation plan; The pedestrian walkway provides a safe path for construction workers to enter and exit the interior of the steel box girder; the ventilation opening helps to provide fresh air, expel harmful gases and dust, and improve the air quality inside the box girder during construction.

[0007] (3) Commissioning of the ventilation system: Connect the installed ventilation equipment into the BIM ventilation system and commission it to ensure that the wind direction and air volume meet the design requirements; (4) Construction in confined space for steel box girder: Before entering the confined space for steel box girder construction, ventilation should be carried out for 30 minutes. The wind speed at the end of the ventilation duct should reach 1.2 to 1.5 m / s, and air environment monitoring should be carried out. After the monitoring is qualified, the fan should be stopped, and construction (such as assembly, welding, painting, etc.) can be carried out. During the construction process, the sensor will feed back the air quality, temperature and humidity in the confined space to the BIM ventilation system in real time. When the feedback value exceeds the set threshold, the BIM ventilation system will immediately start the fan in the monitored area that exceeds the standard, or adjust the air outlet direction and air volume of the smart air outlet near the area to accelerate air circulation, promote the exhaust of the air in the area and introduce fresh outside air. When the sensor monitoring parameters fall back to below the set threshold, the fan will stop working to save energy. (5) Clean-up after construction: After construction is completed, clean up the construction site, remove ventilation equipment, and restore the site to its original state.

[0008] Furthermore, the ventilation ducts connected to the fan are positioned 0.8–1.0 m above the ground. Since hot air typically rises while cold air sinks, placing the ventilation ducts at this height can more effectively promote air convection and improve ventilation efficiency.

[0009] Furthermore, the multi-functional monitoring sensors are installed with a spacing of less than 8 meters and a height of no more than 1.2 meters above the ground. The 8-meter spacing ensures comprehensive coverage of the monitoring area, avoiding blind spots and allowing for more accurate monitoring of parameters such as air quality, temperature, and humidity. The 1.2-meter height from the ground provides a more accurate reflection of the environmental conditions in the worker's breathing zone.

[0010] The beneficial effects of this invention are as follows: This invention utilizes BIM technology to perform precise 3D modeling of the confined space inside the steel box girder, simulating the installation process of ventilation equipment. This allows for detailed planning and simulation of the ventilation system before construction, ensuring precise layout of the ventilation equipment and guaranteeing that the airflow direction and volume of the vents cover the entire confined space, achieving optimal ventilation. Simultaneously, by combining intelligent vent technology with BIM technology, this invention achieves precise control of the ventilation system. It can monitor key parameters such as air quality, temperature, and humidity within the confined space in real time and automatically adjust the operating status of the ventilation equipment according to preset indicators, improving ventilation efficiency, reducing energy consumption, ensuring stable air quality within the confined space, and reducing the probability of safety accidents such as oxygen deficiency and poisoning, thus meeting the requirements of green construction. Furthermore, the intelligent ventilation method exhibits extremely high adaptability, allowing for personalized design and adjustment according to different construction conditions. Whether in narrow underground structures or complex urban blocks, it can play an excellent ventilation role, ensuring a safe and comfortable construction environment. Attached Figure Description

[0011] Figure 1 It is a structural diagram of the passageways and ventilation openings reserved on the steel box girder; Figure 2 This is a product image showing a hemispherical air outlet; Figure 3 This is a product image of the latitude steering drive unit. Detailed Implementation

[0012] To make the technical problems and solutions solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0013] Take the "Confined Space Construction Ventilation Project for Steel Box Girder of Yongchang Expressway" as an example.

[0014] Project Location: Bonan Town, Yongping County, Dali Prefecture, Yunnan Province Structural form: Steel box girder structure Physical workload: 60m steel box girder of the first span of the D ramp bridge of Yongping Hub Interchange; 70m+60m steel box girder of the 6th and 7th spans of the left lane of Xiashanjiao Bridge; 70m+60m steel box girder of the 6th and 7th spans of the right lane of Xiashanjiao Bridge; 60m steel box girder of the 10th span of the left lane of Loufangpo No. 1 Bridge; 60m steel box girder of the 10th span of the right lane of Loufangpo No. 1 Bridge; 40m+60m steel box girder of the 5th and 6th spans of the left lane of Chalucun No. 1 Bridge; 2×40m steel box girder of the 5th and 6th spans of the right lane of Chalucun No. 1 Bridge.

[0015] This project adopts the intelligent ventilation construction method for steel box girder construction in confined spaces as described in this invention. The specific steps are as follows: (1) Preparations before construction A 3D model of the steel box girder was created using BIM software, including its internal structure and spatial layout. Based on the 3D model, the construction plan was simulated and optimized to determine the optimal layout and material requirements for ventilation equipment (see Table 1). Simultaneously, the 3D model was updated using site survey data to improve the accuracy of the construction plan.

[0016] Table 1: List of Ventilation Equipment (taking a 100m steel box girder as an example)

[0017] This project consists of 620m of steel box girder, and includes the installation of 20 intelligent air outlets, 40m of ventilation ducts, and 13 fans (for repeated use).

[0018] (2) Installation of ventilation equipment The installation process of ventilation equipment is simulated in the BIM model, including the location and connection methods of intelligent air vents (using hemispherical air outlets), ventilation ducts, exhaust fans, and multi-functional monitoring sensors, ensuring that the layout of the ventilation equipment can cover the entire limited space. Special attention should be paid to the following: the distance between the ventilation ducts connected to the fans and the ground should be 0.8–1.0m; the installation spacing of the multi-functional monitoring sensors should be less than 8m, and the height from the ground should not exceed 1.2m. Simultaneously, the locations of the passageways and ventilation openings that should be reserved on the steel box girder should be accurately marked in the BIM model (e.g., ...). Figure 1 Ensure that these structures are properly reserved during construction; install ventilation equipment according to the model simulation plan.

[0019] (3) Commissioning of the ventilation system Connect the installed ventilation equipment to the BIM ventilation system and test it to ensure that the airflow direction and volume meet the design requirements. During the testing process, check whether the settings of various parameters of the control system (see Table 2) are correct and whether the sensitivity and accuracy of the sensors meet the requirements.

[0020] Table 2: Threshold Setting for Gas Monitoring in Confined Spaces

[0021] (4) Construction of steel box girder in confined space Before entering the confined space of the steel box girder for construction, ventilation should be carried out for 30 minutes. The wind speed at the end of the ventilation duct should reach 1.2 to 1.5 m / s, and the air environment should be monitored. After the monitoring is qualified, the fan should be stopped, and construction (such as assembly, welding, painting, etc.) can be carried out.

[0022] During construction, sensors will provide real-time feedback on air quality, temperature, and humidity in the confined space to the BIM ventilation system. When the feedback value exceeds the set threshold, the BIM ventilation system will immediately start the fans in the monitored area, or adjust the airflow direction and volume of the smart vents near that area to accelerate air circulation, expel the air from the area, and introduce fresh outside air. When the sensor-monitored parameters fall back below the set threshold, the fans will stop working to save energy.

[0023] (5) Cleaning after construction After the construction is completed, the construction site will be cleaned up, the ventilation equipment will be removed, and the site will be restored to its original state.

[0024] This embodiment uses an existing intelligent air outlet—a hemispherical air outlet (see...). Figure 2 Its specific structure is as follows: The hemispherical air outlet includes an arc-shaped air outlet plate with dehumidifying vents for effective dehumidification. The upper hemispherical air outlet unit also includes two symmetrically arranged follower spherical components along the arc-shaped air outlet plate. These components are positioned on either side of the plate, with arc-shaped grooves at their contact points with the plate. Arc-shaped protrusions on both sides of the arc-shaped air outlet plate mate with these grooves, ensuring stable and smooth rotation. An arc-shaped sliding plate is located at the outer bottom edge of each follower spherical component, and a circular inner groove is formed on the inner top side of the lower hemispherical base. The arc-shaped sliding plate slides within this groove, guaranteeing stability and accuracy during rotation. A fixing post, which engages with a fixed sleeve, is located on the inner side of each follower spherical component, allowing for close cooperation between the upper hemispherical air outlet unit and the weft steering drive unit for precise rotation control.

[0025] Steering drive unit for hemispherical air outlet: 1. The meridional steering drive unit controls the rotation of the air outlet arc plate. Its working principle is as follows: A vertical connecting rod is rotatably connected to the surface of the first driven gear. The lower end of the vertical connecting rod is connected to the second driven gear. An air guide pipe is installed through the center of the first driven gear. The lower end of the air guide pipe passes through and is rotatably connected to the lower base plate. A second drive gear meshing with the second driven gear is rotatably connected to the air guide pipe. A driven pulley is fixedly installed at the lower part of the second drive gear. A second drive motor is also fixedly installed at the lower part of the lower base plate. The output shaft of the second drive motor is connected to the drive pulley. The drive pulley and the driven pulley are connected by belt drive. The upper end of the vertical connecting rod is connected to the drive bevel gear. A horizontal rotating shaft is rotatably connected between the upper ends of the support ears. One end of the horizontal rotating shaft is equipped with a driven bevel gear that meshes with the drive bevel gear. The other end of the horizontal rotating shaft is equipped with an arc plate drive gear. An arc plate rack that meshes with the arc plate drive gear is installed on the inner side of the air outlet arc plate. Through this transmission structure, the second drive motor drives the active pulley to rotate, which in turn drives the driven pulley and the second drive gear to rotate via the belt. This, in turn, drives the second driven gear and the vertical connecting rod to rotate. Finally, through the transmission of the active bevel gear, the driven bevel gear, the horizontal rotating shaft, and the arc plate drive gear, the meridional steering of the air outlet arc plate is achieved.

[0026] 2. Latitude steering drive unit (see) Figure 3 This device controls the rotation of the upper hemispherical air outlet unit. Its working principle is as follows: A rotating turntable connected to the center of the upper top plate has two supporting ears on its upper part. Fixed sleeves are respectively installed on the outer sides of the upper ends of the supporting ears. A first driven gear is fixedly installed on the lower part of the turntable. A first drive gear meshes with the first driven gear on one side. A first drive motor is fixedly installed on the lower part of the lower base plate. The output shaft of the first drive motor is connected to the center of the first drive gear via a drive shaft. The first drive motor drives the first drive gear to rotate, which in turn drives the first driven gear and the turntable to rotate. Through the cooperation of the fixed sleeves and the fixed inserts on the inner side of the follower spherical component, the upper hemispherical air outlet unit achieves latitude-to-latitude rotation.

[0027] The aforementioned hemispherical air outlet and its steering drive unit are existing technologies, as detailed in the description of an intelligent air outlet in a steel box girder dehumidification system disclosed in CN115506225A. This intelligent air outlet can automatically adjust its direction on a hemispherical surface through external control connection, expanding the air delivery area and reducing the number of fans required while ensuring ventilation effect.

[0028] Compared with traditional construction methods, the intelligent ventilation construction method described in this invention has significant advantages and novelty in terms of technical and economic efficiency, such as construction period, quality, safety, and cost, as shown in Table 3.

[0029] Table 3: Comparison of the advantages of different ventilation methods Serial Number Job duties Traditional construction methods Intelligent ventilation method 1 Construction period Workers cannot work continuously and need to rest for 5 to 10 minutes outside the box girder every half hour or so. A total of 12 welders and 3 painters are needed. It can operate continuously and in a comfortable working environment, requiring only 8 welders and 2 painters to meet the requirements. Moreover, continuous operation can shorten the construction period by 20%. Taking a 100m box girder as an example, the installation period can be shortened by 7 days. 2 quality The inability to maintain a good working environment affects the quality of construction. A good working environment is conducive to improving construction quality, and the BIM 3D model can provide precise installation guidance, further ensuring construction accuracy. 3 Safety It is difficult to ensure that air quality consistently meets standards. Dynamic monitoring and real-time adjustment of air quality indicators ensure that air quality continuously meets construction requirements. 4 cost Some ventilation operations are ineffective and wasteful. The air outlets can be adjusted in direction, reducing the number of fans required and lowering equipment investment costs. Simultaneously, fan start / stop and airflow can be precisely controlled, effectively avoiding waste and thus saving on operating costs. The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart ventilation construction method for steel box girder construction in confined spaces, characterized in that, Includes the following steps: (1) Pre-construction preparation: Use BIM software to build a three-dimensional model of the steel box girder, simulate and optimize the construction plan based on the three-dimensional model, and determine the optimal layout and material requirements of the ventilation equipment; at the same time, combine the on-site survey data to update the three-dimensional model and improve the accuracy of the construction plan. (2) Ventilation equipment setup: Simulate the installation process of ventilation equipment in the BIM model, including the location and connection method of intelligent air outlets, ventilation ducts, exhaust fans, and sensors, to ensure that the layout of ventilation equipment can cover the entire limited space; at the same time, accurately mark the location of human passages and air vents in the BIM model to ensure that these structures are correctly reserved during construction; install the ventilation equipment according to the model simulation plan; (3) Commissioning of the ventilation system: Connect the installed ventilation equipment into the BIM ventilation system and commission it to ensure that the wind direction and air volume meet the design requirements; (4) Construction in confined space for steel box girder: Before entering the confined space for steel box girder construction, ventilation should be carried out for 30 minutes. The wind speed at the end of the ventilation duct should reach 1.2 to 1.5 m / s, and air environment monitoring should be carried out. After the monitoring is qualified, the fan should be stopped, and construction can begin. During the construction process, the sensor will feed back the air quality, temperature and humidity in the confined space to the BIM ventilation system in real time. When the feedback value exceeds the set threshold, the BIM ventilation system will immediately start the fan in the monitored area that exceeds the standard, or adjust the air outlet direction and air volume of the smart air outlet near the area to accelerate air circulation, promote the exhaust of the air in the area and introduce fresh outside air. When the sensor monitoring parameters fall back to below the set threshold, the fan will stop working to save energy. (5) Clean-up after construction: After construction is completed, clean up the construction site, remove ventilation equipment, and restore the site to its original state.

2. The intelligent ventilation construction method for steel box girder construction in confined spaces according to claim 1, characterized in that, The ventilation duct connected to the fan is 0.8 to 1.0 meters above the ground.

3. The intelligent ventilation construction method for steel box girder construction in confined spaces according to claim 1, characterized in that, The sensors are installed with a spacing of less than 8m and a height of no more than 1.2m from the ground.

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