The steel column should have a reliable connection with the reinforcement cage.
Elevation control can control the elevation of lattice column by welding reinforcement on the limbs at the end of lattice column.
4.
2.
The lap length shall be in accordance with the specification requirements, and the welding requirements shall be consistent with the requirements of the engineering pile, which must meet the specification requirements.
When bearing horizontal loads, it is easy to lose stability and damage.
During the fabrication of lattice columns, attention must be paid to the flatness of angle steel, and the angle steel needs to be straightened before fabrication.
5 process flow and operation method 5.1 construction process flow chart 5.2 construction operation method 5.2.1 welding of lattice column.
Therefore, sufficient vertical supports must be set.
The scope of application is applicable to all deep foundation pit retaining works requiring horizontal support, especially those with large foundation pit width and depth and reinforced concrete horizontal support.
3.
Steel lattice columns play a key role in the stability of foundation pit horizontal support.
The reinforcement welded on the lattice column is used to make up for the top elevation that cannot be observed after the lattice column is placed in the hole, as shown in figure 5.2.3-2.
The variety, specification and model of the welding rod must be qualified.
Key points of installation quality: in order to ensure the verticality of the steel column, the verticality of the lattice column should be monitored during installation.
Lattice column assembly and welding: if the lattice column is long and inconvenient for transportation, the lattice column shall be assembled and welded in sections.
Cracks, slag inclusions, weld beading, burn through, arc craters, needle shaped pores, fusibility splash and other defects are strictly prohibited.
5.2.3 lattice column placement.
The main reinforcement of the reinforcement cage shall be reliably and firmly welded with the lattice column.
Hoisting, transportation and stacking of lattice columns: steel lattice columns shall be hoisted by crane, which shall be lifted slowly and handled gently.
Therefore, the construction technology of deep foundation pit enclosure is gradually from innovation to maturity, As the vertical support of deep foundation pit support, steel lattice columns are more and more widely used.
This article is a record of the construction of supporting lattice columns in the foundation pit of a project.
During welding, both sides must be welded symmetrically.
3.
The weld seam of the welding position must be full, and the welding quality meets the requirements of the technical specification for welding of building steel structures.
If deformation and bending are found in the process of manufacturing and transportation, it should be dried with oxyacetylene in time.
Lattice column material mobilization batten plate processing material angle steel mobilization welding platform material mobilization inspection steel plate thickness inspection angle steel welding semi-automatic cutting machine, cutting batten plate long side cutting is very convenient, welding machine welding finished joint after splicing, lattice column and reinforcement cage are placed together after welding, the size of lattice column 460*460 lattice column is placed together with reinforcement cage during cast-in-place pile construction, and the insertion into the pile is not less than 3 meters, quality requirements 1 Raw materials: the angle steel and steel plate of lattice column shall be purchased in strict accordance with the drawings and specifications, and the factory certificate and test report must be provided.
Under the construction process, the tremie should be used for column pile concrete pouring.
If it is put down, the lattice column will continue to sink, and the final result will make the vertical support system fail..
Let’s have a look at it! Operation process 1.
Perpendicularity can be controlled by theodolite, as shown in figure 5.2.3-1.
After the concrete is poured, the lattice column cannot be completely put down, because the lattice column itself is heavy, and the hole depth is far more than the length of the lattice column.
2.
1.
During construction, attention must be paid to controlling the verticality and elevation of lattice columns.
2.
Fixation of steel lattice columns.
Manual welding is adopted at the connection between the batten and the angle steel.
Figure 5.2.3-2 elevation control 3.
3.
The weld surface should be uniform and smooth, without wrinkles, discontinuities and incomplete welding, and should be smoothly connected with the base metal.
In the construction of internal support of foundation pit, lattice column construction technology is mostly used for vertical support, which has the characteristics of high strength and good rigidity, and has good force transmission, earthquake resistance, fire resistance and corrosion resistance, which plays a key role in the stability of horizontal support of foundation pit.
The welding belongs to class II welding, as shown in Figure 5.2.1.
The steel lattice column with strong rigidity and good force transmission can be used as the vertical support, so that its upper end is anchored in the support structure and its lower end is anchored in the engineering pile, which can ensure the stability and safety of the foundation pit in the foundation construction stage of the project.
Figure 5.2.3-1 perpendicularity control 2.
In combination with the construction technology of steel lattice column driven into bored cast-in-place pile as the supporting fulcrum of retaining wall, which has been successfully applied by our company in many deep foundation pit retaining wall projects, this construction method is prepared for application and promotion in future deep foundation pit retaining wall projects.
The first layer of support construction the first layer of support construction the second layer of support excavation the second layer of support excavation the second layer of support excavation the second layer of support excavation the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction the second layer of support construction attached to a project lattice column construction scheme example directory 1 preface 2 features 3 scope of application 4 Process principle 5 process flow and operation methods 6 material requirements 7 machines and equipment 8 labor organization 9 safety measures 10 quality control measures 11 benefit analysis 12 project example 1 preface with the rapid development of social economy, there are more and more high-rise and super high-rise buildings in cities, and the foundation of urban buildings is also deepening downward.
Figure 5.2.1 lattice column welding 5.2.2 ensure the straightness of lattice column.
Clean raw materials before cutting, reserve appropriate welding shrinkage allowance and cutting allowance, and save materials as much as possible.
Ensure the verticality of lattice columns.
Installation and positioning of lattice column: after the lattice column is hoisted into the pile hole, it shall be firmly welded with the reinforcement cage.
4.
Process principle the horizontal support structure has a large self weight and span.
Welding requirements: the welding requirements of lattice columns are high.
Setting out and marking off of lattice column: the lattice shall be constructed according to the design requirements.
Features: steel lattice columns with four limbs are used as the vertical support of deep foundation pit enclosure, which has the characteristics of high strength, good rigidity, good force transmission, seismic resistance, fire resistance and corrosion resistance.
