Space frame installation technology of a large barrel closed coal bunker

Figure 1 Completed coal bunker

The barrel-closed coal bunker has the advantages of being closed, environmentally friendly, and storing coal in separate piles. It can not only protect coal combustion and operation from the influence of climate conditions but also avoid the environmental pollution caused by coal dust escape. With the improvement of environmental protection requirements, there will be more and more applications of strip-shaped closed coal storage shed in the water transportation industry. According to the characteristics of different projects and site conditions, construction techniques can be different but have similarities. 

According to the requirements of environmental protection, the first phase of the coal terminal project in the Tsuenwan port area of Huizhou Port in Guangdong adopts a large strip-shaped closed coal bunker to store coal (Figure 1). Combined with the project characteristics and site conditions, to speed up the installation efficiency and improve the installation accuracy, the space frame adopts the overall jacking process, the strip and block top hanging process, and the high-altitude bulk process for installation. During the installation process, the superstructure of the reticulated shell is fully, systematically, and automatically monitored for the whole process, and the construction of the reticulated shell is measured simultaneously to ensure the quality and safety of the installation. The successful implementation of this project can provide examples and experience for similar projects of water transportation engineering.

1 project overview

The project is located in the Tsuenwan port area of Huizhou port, near Chunzhou Island, consisting of two bar-shaped closed coal bunkers used to store coal. The single bunker is 500m in length, 118m in span, 43.7m in height, 57,500 square meters in the construction area, and 74,500 square meters in spread area, of which the straight section is 441m in length, the radius of the hemispherical shell at the end is 59m, the radius of the great three-center circle is 71.4m, and the radius of the small circle is 36m(FIG. 2 and 3).  

Figure 2 Perspective view of a single coal bunker space frame

Fig. 3 Sections of straight-line section and spherical shell section of a coal storage shed

The foundation of the coal bunker is the maintenance structure of bored piles + anchor rods + concrete columns, coal retaining walls, and brick walls, and the elevation of the bearing surface is 4.3m. The upper part of the coal bunker is a space frame + purlin + high-strength pressure steel plate structure. The space frame adopts a positive-placed quadrangular pyramid double-layer three-center cylindrical arc-shaped space frame shell structure. The space frame size is 4m long, 4m wide, and 3.5m thick. Support, the node types are bolt balls (upper part of the space frame ), welded balls (the lower part of the space frame ), intersecting nodes, the primary and secondary purlins are arranged in double layers, and the main purlins are high-frequency welded H-beam H200mm×150mm×3.2mm×6mm, The secondary purlin is XZ160mm×60mm×20mm×2.2mm; the total steel mesh frame is about 7000t, and the primary and secondary purlins exceed 1400t.

2 Project Features

1) For the construction of the isolated island, people, machines, and materials must be transported to and from the island by ship, which is inconvenient for transportation.

2) The construction period is tight. In addition to the total construction period requirements of the project, the main space frame structure must be completed before the typhoon-prone season.

3) The installation of the upper space frame and the construction of the coal bunker foundation have to be ordered to cross operate in the limit site.

4) A stacker-reclaimer embankment with a width of 15m and a height of 1.8m has been completed in the middle of the coal bunker along the length direction, and two belt conveyors are installed on the embankment.

3 Selection of space frame installation process

The space frame structure is widely used in the field of large-scale infrastructure construction in China and is suitable for industrial and civil buildings with various supporting conditions and various plane shapes and spans, such as stadiums, theaters, exhibition halls, waiting halls, hangars, two-way large columns from the workshop, etc. The space frame structure has its unique advantages: the span and height of the structure can be larger, the rigidity of the structure space is large, the integrity and stability are good, and it has good seismic performance. On the premise of satisfying the use, a beautiful building can be designed Modeling; shortcomings: the number of structural rods is large, and the production and installation are more complicated than the plane structure.

Combined with the characteristics of the project and the site conditions, to speed up the installation efficiency and improve the installation accuracy, the coal bunker space frame of the project adopts a combination of the overall jacking process, the strip and block top lifting process, and the high-altitude bulk process for installation, and the construction is divided according to the expansion joints of the space frame. In the area, the linear section space frame is installed by the overall jacking process and the strip and block top hanging process, and the end hemispherical shell and the connecting section space frame are installed by the high-altitude bulk process.

4 Space frame installation process

4.1 Lifting process

The project selects mature, safe, and reliable hydraulic jacks as the jacking equipment. The jacking bracket draws on the design concept of the bolted ball space frame and tower crane and takes 1.1m as a standard section. The standard section and the standard section are connected by bolts, dismantled, and installed. Convenient; the hydraulic jack is specially made, the lifting capacity is 50t, the height is 2.1m, and the stroke is 1.1m; the hydraulic jack is installed on the bottom base of the jacking bracket, and the upper part is connected with the space frame node and is firmly fixed. After debugging and checking the safety Start jacking up, the space under the bracket is larger than the test, check the safety, start the jacking, and stop the jacking after the space under the bracket is larger than 1.1m, and install the next standard section to the bracket at the lower part of the bracket (standard section). After the standard section is installed, the hydraulic jack falls back, so that the bracket falls on the base below, and the hydraulic jack moves down to lift the support point; continue to the next cycle, repeat the operation, lift 1.1m each time, until The space frame is raised to the design height.

4.2 Slit and block ceiling hanging process

The space frame is divided into strip-shaped units with a width of 5 volleyballs. After the ground is lifted and assembled and formed, it is symmetrically suspended to the middle of the sky and closed to form a whole.

1) The unit is assembled on the ground from the first row of bolt balls on the longitudinal sides of the space frame, and the temporary support is set up to assemble to the middle of the space frame. After the height of the jacking bracket is satisfied, install the hydraulic jack and the jacking bracket to lift and assemble. After assembling each volleyball, add temporary support under the ball. After checking the temporary support and confirming that it is safe and reliable, disassemble the jacking bracket and move it to the assembled ball. After the assembly is completed, it is then jacked up. assembled.

2) The jacking bracket is raised to a height of 20m, and the lifting part of the space frame is fixed with steel wire ropes (Fig. 4) to control the arc-shaped outstretching of the space frame. According to the check calculation, when the 1/4 span of the assembly is completed, the first tension wire rope is added. , One end of the tensioning wire rope is set with a hand hoist to control the size of the mesh shell; when the mesh frame is installed to the middle plan closing part, a second tensioning wire rope is added.

Figure 4 Jacking device plus tensioning wire rope

3) Then move the jacking device to the starting side, continue to jack up the space frame for the welding ball part, until the jacking device is installed on the bearing ball, use a crane to hoist the bearing ball end to the base support; After passing the calibration test, lift the assembled mesh frame on both sides with a crane in the middle at the same time and fold it up in the middle of the sky to form a whole (Figure 5, 6). And remove the tension wire rope.

 Figure 5. Slitting and block ceiling hanging process of space frame 

Figure 6. The space frame is divided into blocks and the ceiling is closed at a high altitude

4.3 Overall jacking process

The unit is assembled on the ground from the first row of bolt balls on one side of the longitudinal side of the space frame until the space frame is assembled and jacked up to the other side of the foundation support; then move the jacking device to the starting side, and continue to lift and install the welding balls Part of the mesh frame until it is lifted to the base support; after the mesh frame is calibrated and tested, the mesh frame is fixed on the base support.

4.4 The high-altitude bulk method uses a crane to hoist the small assembled unit at high altitude (Figure 7), assemble it from the bottom to the top from the installed space frame to the end hemispherical shell, and check the installation accuracy at any time.

Figure 7 The high-altitude bulk method

4.5 Main points of space frame installation

1) The space frame members and nodes are pre-assembled into units on the ground, which greatly reduces the amount of aerial work.

2) Simulate the stress and deformation of the space frame during the construction process through computer technology, accurately arrange the jacking points, determine the jacking sequence, and monitor the jacking process in real-time.

3) During the lifting process, the synchronization of the lifting equipment should be strictly controlled to ensure the stable lifting of the space frame. The space frame of the project is a cylindrical arc reticulated shell structure. With the lifting of the space frame, the jacking device will incline to the landing end of the space frame. A temporary top can be added to adjust the position of the lifting device; the jacking equipment is equipped with a hydraulic Large oil cylinder, temperature control system, and electric synchronous adjustment mechanism, the whole system is controlled by y computer, the lifting of multiequipmentsment adopts electronic control synchronization, electronic servo automatic oper, action and field bus control, and other technologies, with remote control function, hydraulic system lifting and lowering It can be lifted as a whole, or it can be adjusted separately by extension, to ensure the synchronization of lifting, and the error of synchronous lifting and the distance between each lifting equipment does not excemmm0mmm.

4) Before jacking, it is necessary to check whether the force of the rod needs to be strengthened during jacking to ensure the strength and rigidity of the space frame unit; the lifting part of the space frame is fixed with steel wire ropes to control the arc-shaped outstretching of the space frame, and the tension must be checked. The force condition and setting position of the wire rope.

5) The size of the strip unit of the space frame for the top-hanging process by strip and block must be checked and reviewed in combination with the strength and stiffness of the space frame unit and the capacity of the on-site crane. EaEvery row of support ball-width space frame strip units has a projected length of 59m, a width of 16m, and a mass of about 57t. First, use a crane to lift the ball end of the support to the base support, and then use two cranes to lift two cranes at the same time in the middle. The strip-shaped units of the side space frameforeclosedandd connected in the middle of the high altitude (about 43m) to form a whole. The crane capacity is required to be ≥200t, the turning radius is 10m, and the lifting capacity is not less than 35t when the arm length is 43.3m. One 220t and one 260t crane is actually onion it.

EEpsilonsite

1) Combined with the characteristics of the project and site conditionstoteoe installation efficiency and improve the installation accuracy, the space frame is installed bybinationcombinationerall jacking process, the strip, and block top lifting process and the high-altitude bulk, process, and the construction area is divided according to the expansion joints of the space frame framee linear sectithe ssectilegagames installed by the overall jacking process, the strip and block top-hoisting process, and the end hemispherical shell and the connecting section of the space frame are installed by the high-altitude bulk process.

2) The purlins are pre-assembled on the ground and installed at high altitudes, which can effectively speed up the installation efficiency.

3) During the installation process, the stress and deformation of the space frame during the construction process are simulated by computer technology, and the upper structure of the space frame shell is automatically monitored in a comprehensive, systematic and whole p,rocess. Ensure insinstantant quaquality qualityty

4) Thsafetyt overcomes the limitations of the limited construction space on the installation of the space frame, and adapts meaures to local onditconditionschieve the optimal energy efficiency of the project. The successful implementation of the project can provide examples and experience for similar projects in water transportation projects.

5) This project has withstood the test of the strong typhoon “Mangosteen” on September 16, 2018, which is equivalent to accepting a full-scale wind tunnel test, with excellent wind resistance performance, which proves that the construction conforms to the design and is perfectly integrated with the design.