What Is Excavation Top Down Construction Methods?

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By Marilyn Royce

Top-down construction is a relatively new earth retention method that is gaining traction in construction companies in Calgary or wherever you live. The top-down approach has been employed for deep excavation projects where tieback installation was impractical, and soil movements were to be kept to a minimum. This method could cut down overall building time.

This article will briefly discuss the top-down construction methods of excavation.

Process Of Excavation Top-Down Construction Methods

The top-down excavation method is typically employed by general contractors in Calgary or nearby. This method allows for the execution of underground floors up to the ground level in the following circumstances:

  • High groundwater table
  • Interference with main street traffic due to performance space limitations
  • Impossibility of securing consent from adjacent neighbors.

There are two types of construction provided by excavating contractors near you:

  1. towering buildings with deep basements
  2. underground structures like parking garages, underpasses, and subway stations.

The top-down building process provided by the general contractor in Calgary or its surroundings may differ for each project depending on its type and individual conditions.

There are the following stages of the top-down construction method:

1.   Construction of The Adjacent Retaining Walls

Retaining walls are sometimes built to a specific depth below the foundation level at the start of a project; this can build barriers in one of these ways:

  • Reinforced concrete wall in situ
  • Diaphragmatic walls
  • Continuous candles Secant heaps
  • Sheet stacks of steel
  • Columns with Jet-Grouting

Diaphragm retaining walls are more commonly employed by construction companies in Calgary or its surroundings than other methods.

2.   Drilling

The second step is the Drilling. The placement of bearing piles from below the level of columns, ground walls, and bearing column installation using one of the following methods:

  • Based on available drilling equipment, an in-situ concrete column with square, rectangular, or circular sections
  • Concrete precast column
  • Combined Slender columns with a concrete jacket during the main structure’s construction
  • Steel composite column

3.   Ground Floor Slab Installation

Following the completion of the main structure’s columns and considering the location of the access apertures to the lower levels, the ground floor slab at the top level of the piles and the surrounding walls on the columns are reinforced and concretized.

Each basement floor’s concrete slab works as a strut, preventing the excavation from collapsing.

4.   Begin Excavation on The Basement Floor.

When the ground floor slabs are finished and the slab concrete is laid down with appropriate machinery, the top-down excavation procedure continues at the openings till the lower roof level. After reaching the lower and flat roof level, work on the natural floor so that it can be regulated. The processes of reinforcing and concreting the roof start after that.

The roof is connected to the columns and surrounding walls by welded or mechanical connections on pre-installed waiting plates. At this point, general contractors in Calgary or nearby should consider the following factors:

  • Soil layer condition
  • Precision drilling height
  • Choosing powerful machines with lower heights

5.   Reinforcement and Concreting

After excavation, foundation, and machine evacuation, the second layer of concrete encircles the diphragm wall (usually the inner part), and the steel will be reinforced and poured. This approach uses piles.

Conclusion

The top-down excavation method permits the superstructure and substructure to be built concurrently. The vertical load capacity of the wall and internal column supports must be sufficient to support the rising superstructure load during the construction sequence.

Access to the substructure works through the superstructure works can be a crucial issue on tiny constricted sites. Check the soil layer conditions before hiring local excavating contractors and you can search on google “excavating contractors near me” to find contractors nearby you.