Sheet pile walls are retaining walls constructed to retain earth, water or any other filling materials. These walls are thinner in section compared to masonry walls. Sheet pile walls are generally used for following:
1. Water front structures, i.e. in building wharfs, quays and piers.
2. Building diversion dams, such as cofferdams
3. River bank protection
4. Retaining the sides of cuts made in earth
Sheet pile walls can be of timber, reinforced concrete or steel.
Timber sheet piles are generally used for short spans and to resist light lateral loads. They are mostly used for temporary structures such as braced sheeting in cuts. When timber sheet piles are used in permanent structures above water level, they require preservative treatment and even, but still their life span is relatively short. Timber sheet piles are joined to each other by tongue and grove joints. Timber sheet piles are not suitable for soils consisting of stones, as the stone would dislodge the joints.
Fig. Timber sheet piles
Reinforced concrete sheet piles are precast concrete members, usually with a tongue and groove joints. Typical section of the RCC sheet pile is shown in figure below. These piles are relatively heavy and bulky. They displace large volumes of solid during driving. This large volume displacement of soil tends to increase the driving resistance. Due to this reason, suitable reinforcement is provided considering large driving stresses.
Steel sheet piles are most commonly used. Steel sheet piles possess several advantages over other piles. They are:
- Steel sheet piles are resistant to high driving stresses
- They are lighter in section
- They can be used several times
- They can be used either below or above water and have long life span
- Suitable joints can be provided to have a continuous wall
- The pile length can be increased either by welding or bolting.
Sheet pile walls wall available in several shapes. Some of the sections are shown below:
Fig. Straight sheet pile
Fig.: Shallow arch web sheet pile
Fig.: Arch web sheet pile
Fig.: Z-shaped sheet pile
The arch and Z-piles are used to resist large bending moments. For less bending moments, shallow arch piles with smaller section modulus are used. Straight web-piles are used where the web will be subjected to tension, as in cellular cofferdams.