Building the Burj Khalifa on desert sand was a major engineering challenge, but it was solved with smart foundation design and advanced construction techniques. Here’s how they did it:

1. Geotechnical Surveys

Engineers conducted extensive soil tests to understand the properties of the sandy and weak rock beneath the site. While it’s desert sand at the surface, underneath there’s a mix of sand, silt, and weak rock like calcified coral and sandstone.

2. Deep Pile Foundations

To anchor the skyscraper:

• 192 reinforced concrete piles were drilled into the ground.
• Each pile is 1.5 meters in diameter and about 50 meters deep.
• These piles reach down to denser layers of soil and rock that can bear the weight.

3. Thick Concrete Raft

• A 3.7-meter-thick concrete mat (called a raft) was built on top of the piles.
• This raft spreads the load of the entire structure and acts like a base plate.

4. Concrete Mix for Harsh Conditions

• The concrete used was specially mixed to resist the salty groundwater, high temperatures, and expansive soil.
• They added fly ash and microsilica to increase durability.

5. Settlement Management

• The entire design anticipated gradual settlement over time.
• Sophisticated monitoring systems track movement to ensure everything remains stable.

So, the secret is: not building on loose sand, but drilling deep past it, anchoring into more solid layers below, and using a massive foundation system to spread and support the load.