The magazine “Big Project ME” is the leading magazine about the construction industry in the Persian Gulf countries.

In the construction of high-rise buildings, increasingly prevailing in urban silhouettes across the country, the use of piles remains a mandatory requirement. In Dubai, the most common technology is the installation of bored piles, says Peter Titus, managing director of Total Foundation Solutions (TFS), which supplies specialized equipment for the construction of deep foundations and piles throughout the Persian Gulf. However, alternative pile technologies are increasingly being used, such as the installation of piles by the continuous hollow auger (CFA) method due to its economic efficiency. According to Titus, CFA prevails in the USA, Western European countries and a number of South American countries, because this method is much cheaper. Everyone is trying to reduce the costs of the entire construction, not just the foundations. Specialists are looking for ways to do this work faster and cheaper and, thus, CFA has become the main technology in France, Spain and the UK.The installation of the CFA pile takes place using a continuous hollow auger immersed in the ground. Continuous fastening of the borehole walls is provided by a ground-filled auger, which eliminates the need to use a temporary casing pipe or bentonite mortar. After reaching the required depth, concrete is pumped through the hollow part of the auger as it is continuously extracted, and the reinforcement frame is immersed in concrete after the soil has been extracted using the auger.
According to Titus, in addition to its economy, another key advantage of CFA is speed. The time spent on the device of each pile is reduced. Drilling a well with an auger, pumping concrete, lifting and sinking the frame takes approximately one-fourth or one-fifth of the time that drilling with a Kelly rod takes.
However, CFA has limitations on the diameters and depth of piles. CFA piles can be drilled to a depth of up to 41 meters and a diameter of up to 1.5 meters using special drilling rigs with high torque. The construction of very tall buildings, such as the Burj Khalifa skyscraper, requires the installation of piles with much larger diameters and depths than can be done using CFA technology. For such cases, installations for the device of bored piles are more suitable. Titus also notes the growing popularity of microswire machines. All machines of this type are used to create holes in the ground, temporary or permanent. The problem lies in the heterogeneity of the soil. In addition, in coastal areas, the groundwater level is quite high, and when the contractor performs excavation work below this level, water begins to appear. Contractors, as a rule, overcome this problem by dewatering with pumps, which is a very expensive process. An alternative option is to create a bottom plug by cementing. Jet grouting is a technology of pile construction by mixing soil and cement mortar under pressure to create a cement-soil column.
Jet cementation improves the mechanical properties of soils, while reducing their water permeability. The bottom plug can be created much lower than the ground level by installing a set of short columns using jet cementation technology by superimposing to stop the flow of water at the site of the future excavation. Commenting on how the market adapts to the current conditions, Peter Titus notes that while machines for the installation of walls in the ground were key equipment in the past, now installations for the device of microswitches have become much more in demand due to the further development of construction technologies.
There are many significant buildings that need to be preserved. Some of them had problems with subsidence and uneven precipitation. Also, some customers are considering the possibility of expanding existing buildings, which will also require strengthening the foundation. The pronounced trend of the transition to micro-trams involves the use of small machines that can be placed inside and buildings, between or under them. The same machines can be used for jet cementation when using a high-pressure pump. Such technologies are becoming more and more popular, since the use of central drilling rigs is not always required. It comes to an understanding that, for example, large-diameter piles are simply not needed under a private house (villa).