Overall summary of the residential project of Zaafaranieh-Sharestan (geotechnical studies):

Residential project of Zaafaranieh-Sharestan 6^th is one of the excavation and stabilization projects of Istasazeh corporation in the district of Zaafaranieh. The project site area is 1100 square meters and the maximum depth of 14 meters. Istasazeh corporation was responsible for the geotechnical studies, demolishment of the existing structures, design and construction of the excavation walls, and the drainage system.

Challenges of the residential project of Zaafaranieh-Sharestan (geotechnical studies):

Every civil construction has its own specific challenges. In the Zaafaranieh-Sharestan project the first challenge was the existence of a deep made-up ground. The existence of made-up ground is something normal in civil projects, but in this project the depth of these made-up ground was so much that it created a risk of bleeding. The whole area of this projects was consisted of two separate lands, thus the depth of the made-up ground on the western side varied from 1 to 3.5 meters and the depth of the made-up ground on the eastern side varied from 3 to 6 meters which made the eastern side more challenging for constructions.

Another challenge in Zaafaranieh-Sharestan project was the reconstruction of the existing buildings, specifically the two swimming pools which were built in the yard made some issues regarding the excavation. The deep concrete at the bottom of the pool caused some delays in the excavation process and caused the machinery to ware out.

One of the other challenges of this project was the existence of big and hard rocks under the ground which made the construction to continue slowly on several occasions. Removing these big hard rocks away from the excavation well required a great amount of time.

Another part of the soil test was the excavation of boreholes by the machines. In addition to the wells, several boreholes were excavated and distributed along the ground. Generally, all the challenges that is faced in the excavation of wells is also present in the excavation of boreholes. The challenges include the risk of bleeding, hitting hard rocks, colliding with the cesspit or the cesspool.

In the Zaafaranieh-Sharestan project one of the other challenges was the machinery being overheated because of the constant drilling of the rocks. These high temperatures caused by the drilling made a lot of the parts to wear out specially the drilling bit.

One other challenge was the escaping water from the boreholes. The existence of open pores in the walls of two boreholes made the water escape possible. Sealing these boreholes to stop the water from escaping was a difficult yet necessary part of the excavation.

The existence of big hard rocks also made sampling very difficult. Cutting the rock and sampling it was by far more difficult than sampling the soil. Hitting the cesspit and the cesspool was another problem. The information about the location of the cesspit and the cesspool was unknown to the previous residents, so little information was available about their location.

Moving the drilling machine from one borehole to another was a problem of its own because the two buildings and many obstacles in the site including working Conex boxes. Using a crane was also problematic so another method had to be used.

Solutions in of the residential project of Zaafaranieh-Sharestan (geotechnical studies):

On the west side of the land, a 1-meter well was excavated which naturally didn’t require any reinforcements but another well with the depth of 3 meters required the reinforcement. The walls of this well were plastered for more reinforcement. On the east side however due to the excessive depth of the made-up ground, the location of the wells had to be changed. When the depth of the made-up ground exceeds 3 meters, plastering cannot help, hence the risk factor increases.

In the Sharestan project the problem of excavation in the made-up ground was fixed by using the drilling mud. Drilling mud is a combination of water, bentonite, and cement. This mud is constantly being pumped into the boreholes during the excavation. As a result, the mud pumps from a well near the borehole to the rod and then exits at the end of the rod and into the borehole. The mud exiting the borehole is then guided by a kennel into the nearby well. This cycle repeats throughout the excavation. This cycle solves to challenges at the same time:

1. Cooling the drilling bit: If the excavation is inside a rock, the drilling bit makes a lot of heat, and it causes the drilling bit to wear out quicker. The drilling mud is very helpful for reducing the heat of the drilling bit. In this project, this method had to use several times because there were rocks in the middle of the way.
2. The second use of the drilling mud is similar to what the plastering offers. It stops the soil from bleeding into the borehole. All the three boreholes that were excavated were existing in the made-up ground.

To method used to move the drilling machinery was similar to skiing. This method requires the ground to be balanced and smooth and resistant enough to withstand the pressure. Leveling the ground in a way that it keeps its resistance was a time-consuming challenge of its own. Also due to the existence of a concrete platform in the middle of the way between first and second boreholes, and the fact that the destruction of this platform was time-consuming, two ramps were used to move the machinery over the concrete platform.