Types of Cofferdams

These cofferdams are built by filling a watertight barrier with soil, clay or sand. The exterior is often sloped to provide additional stability and prevent erosion. They can be easily constructed and adapted at low costs to suit project requirements. Earthen cofferdams are commonly used in locations with a low depth of water flowing at a low velocity. However, they may not be suitable for locations with high water flow or unstable soil conditions.

Rock-filled cofferdams contain rocks or rubble to support the work area. They are particularly useful in areas with rocky terrain, as the existing material can often be used to construct the cofferdam. Rock-filled cofferdams can withstand the forces of water and waves, making them suitable for low-depth water levels where traditional earthen cofferdams may not be suitable. The weight and density of the rocks provide a stable foundation, preventing the cofferdam from being displaced by the surrounding water.

Braced cofferdams are constructed using interlocking steel sheet piles that are supported by horizontal braces. They are commonly used in deep water or in locations with strong currents and high water pressure for the construction of bridge piers and abutments. The cofferdam provides a dry work area for the construction of the foundation and support structures for the bridge. The bracing ensures that the cofferdam walls remain stable throughout the construction process, allowing for safe and efficient work to take place.

Cellular cofferdams are often used in situations where traditional cofferdam structures may not be sufficient enough to withstand large amounts of water. They are commonly used in large-scale construction projects such as bridges and dams. There are two types of cellular cofferdams: circular and diaphragm. Circular cofferdams are made up of interconnected circular cells. On the other hand, diaphragm cofferdams consist of a series of interconnected cells formed by diaphragm walls.

Single-walled cofferdams are typically made of a single row of sheet piles with interlocking mechanisms, that are driven into the ground to create a continuous barrier against water and soil. They are often used in shallow water or where space is limited, as they require less material and are quicker to install than double-walled cofferdams. However, single-walled cofferdams may not be suitable for projects where there is a risk of strong currents, waves or high water pressure.

Double-walled cofferdams contain two parallel walls of steel or concrete sheet piling which are driven into the ground and tied together. The space between the two walls is typically filled with soil for added strength and to prevent the walls from moving or shifting. These cofferdams are commonly used in situations with high water pressure and the need for a more robust structure is required. The two walls provide a greater degree of resistance to the force of the water, ensuring that the structure remains intact and secure.