Integral Jacking Technology of Arch Space Frame

1、Project overview

This project is a coal shed closed renovation project. The project uses an arched space frame. The total length of the space frame is 92.4m, the total span of the space frame is 46.2m, and the elevation is 6.7m. The jacking support adopts 2.43m× The specification of 2.43m. The outer facade of the space frame is arched , and the overall area of the space frame is large , and the overall installation height is high. If the traditional technology is used for construction, it will consume more time to splice the space frame , and the jacking The difficulty and construction risk are high. Therefore, during the construction of the arched space frame of this project, the method of lifting while assembling is adopted , and the jacking equipment is used to cooperate with the splicing of the arched space frame , so that the jacking construction and space frame splicing construction can be carried out At the same time , effectively improve the construction efficiency.

2、Arch space frame lifting technical scheme

Since the construction site of this project is a coal yard in use , and the coal yard is designed with expansion joints, it is necessary to divide the welded ball net frame into two areas during construction, and use 4 hydraulic jacks to control the area of each area. The space frame is jacked up, and the weight of each jacking point is 24T. The construction method of lifting while assembling is adopted, and the space frame is lifted to the top of the column of the retaining wall, and the jacking is carried out in two times to cooperate with the assembly and welding of the arched space frame.

3、Application points of overall jacking technology

(1)Preparation. Before adopting the overall jacking technology to carry out the overall jacking construction of the arch space frame, the corresponding preparations must be done first. For this project, the preparations mainly include the following aspects: first, the inspection of materials, for The space frame materials that have entered the field must be fully counted, and various materials are classified and stacked to ensure easy access. The components such as balls and poles must be strictly inspected, and their dimensions must be strictly in accordance with the design requirements . and specifications to ensure the installation size of the space frame; secondly, the preparation of construction equipment , the mechanical equipment that needs to be used in the construction process must also be strictly inspected , and the equipment that needs to be calibrated must be strictly in accordance with the requirements. Calibration , and pay attention to the protection of equipment , to avoid the impact of the site environment on the normal use of construction equipment; the last is to clean up the construction site necessary to ensure that the construction activities have sufficient working surface, so as to effectively ensure the jacking Quality of construction.

(2)The ground assembly of the space frame. In the process of assembling the arch space frame on the ground, it is first necessary to determine a reasonable assembly sequence. Only by ensuring a reasonable assembly sequence can the welding deformation and welding stress be effectively reduced. According to the actual situation of this project, the ground assembly is carried out in the order of assembly from the middle to both sides for each partition. In the specific assembly process, first of all, the bottom string ball and the bottom string rod are placed on the ground platform according to the design requirements , so that they form a “field” character. Then on the assembled lower chord and the lower chord, the web bar and the upper chord are installed to form a quadrangular cone. After installing the web bars and the upper string balls , install the horizontal rods connected to the upper string balls. After installing the horizontal rods , continue to assemble the space frame in the order from the middle to the two sides until each partition space frame splicing is complete.

(3)Key points for jacking equipment installation. The installation of jacking equipment is also a key link in the overall jacking construction process of the arch space frame structure, which has a very important impact on the quality of the jacking construction. Therefore, in the process of installing the jacking equipment in this project, the jacking The lifting point layout diagram is based on the layout of the jacking point. This space frame has 4 jacking points in each area. The assembly of the lifting equipment is tied to the top of the equipment, and a steel jacking cap is added. The steel jacking cap and the steel string on the space frame The spheres are connected together as vertices. On each set of lifting equipment, 4 fasteners are used to connect, so that the space frame and the lifting equipment form a geometrically invariable system and form a whole. A hydraulic jack is placed at each vertex , and a multi-section lattice load-bearing frame is connected to the top cap at the lower end of the jack , and then the load-bearing frame is connected together with steel pins and high-strength bolts.

(4)Jacking construction points. The jacking construction is the most important link in the overall jacking process of the arch space frame structure , and it is also the link with the highest quality risk and safety risk , so it must be paid enough attention to it , and this project adopts two stages The way of jacking is carried out , so the control of the jacking process is even more important. First of all, before starting the jacking, make the jacking space frame 100mm above the ground, so that the force of each cylinder is basically consistent. Then make the jacking equipment in the safe mode to observe whether there is any abnormal situation such as subsidence on the ground . If there is any abnormal situation on the ground, it must be dealt with first , and the jacking can only continue under the premise of ensuring safety. In the early stage of jacking, it is necessary to increase the frequency of checking the elevation of each jacking point of the arch space frame to ensure that the space frame is raised synchronously. In the process of increasing the height, it is necessary to ensure that the lower bracket bears the force. When the piston rod is fully extended, add a support frame, and then tighten the relevant bolts to make the piston rod retract, and the upper bracket bears the force. After the piston rod is fully retracted, the lower bracket is received at the last stress-bearing place, and the force-bearing rod is moved up to complete a one-step jacking operation. After each jacking stage is over, special staff must be arranged to check the temporary power equipment and jacking equipment to ensure safety. After the first jacking is completed, the corresponding parts of the arch space frames of the two partitions are assembled according to the requirements. During the assembly process, the stability of the entire jacking structure must be ensured. plane position etc. After completing the space frame assembly work at this stage, proceed to the second jacking construction, which is similar to the first jacking construction until the entire space frame is fully lifted in place.

This coal shed closed reconstruction project researches the overall jacking technology in the construction of the arched space frame . There are structures that are fully utilized and lifted in stages , so that the arched space frame can be lifted and assembled at the same time , effectively improving the efficiency and quality of the arched space frame construction.