Sheet Pile Wall Design

Generally in sheet pile wall design, normally we need to calculate all kinds of loads, scour depth, length of sheet pile (including pile embeded depth, the concrete cover thickness) through test algorithm. According to different construction conditions in process aselect sheet pile sections, supporting layers and structure, at last check the overall stability of sheet pile wall.

1. Data Collection
Collect and analyze geological maps, the highest water level, the highest level of construction and so on.

2. Determine Geometry Size
Plane size is often dermined by upper structure and its foundation size. Sheet pile wall construction should be in accordance with the whole project construction and template installation, so the wall’s size should be at least 1.5m greater than the basic outline. It must also consider the needed size of pumping equipment and wells’ installation.

Dimensional size is usually influenced by water level, scour depth, the depth of excavation inside wall and factors such as stability in the pit end. But the most direct impact is water level.

3. Calculate Sheet Pile Wall Lateral Pressure

Assume sheet pile’s embedment depth first, then calculat lateral pressures hydrostatic pressure, water impact, ice pressure, wind, wave power and earth pressure.

4. Force Checking by Constructin Conditions

5. Stability Checking
Need to analyze wall’s overall stability and soil stability at the end of the foundation such as arch, water well-out and sand-cast.

Article Source:   Sheet Pile Wall Design Steps

Sheet Pile Wall Structure Designs on Seriously Weathered Rock Layer

For sheet pile wall or cofferdam construction, normally we need to drive piles to the required depth. But for shallow layer especially seriously weathered rock layer, it is very difficult to drive piles. For instance, top surface of highly weathered rock and sand layer is 1-4m lower than cushion base, and some part is even near the cushion base. Because the driving depth is not enough as required, the displacement at the pile-end will be larger, sheet piles in some project sections would easily get damaged like "kicking damage".

For this problem, we must take some measures on structural design first.

For structral desgin of sheet pile wall, there are mainly three plans to solve the problem :

1. Enlarge the wall or cofferdam and put slope inside;

2. Increase inside support layers;

3. Reinforce the bottom of sheet piles;

Sheet Pile Wall or Cofferdam

Comparing three plans above, if only by plan 1, because the wall or cofferdam is normally large enough, it will cost extra money or time. And if there are more wall or cofferdams in construction at the same time, it will influence other projects too; Just by plan 2, if we increase inside support layers when excavation near the end, supports' changing process will be more complicated when it comes to the back concrete cover; If just by plan 3, although it is applicable in theory, it is not enough for pratical construction.

The best way actually is to combine the strong points of the three plans. For instance, firstly, we can set the axis line of sheet pile wall near the cap side which will proive a certain slope space and is useful for sheet pile reinforcement.Secondly, set 6 layers of inside support,make the space wider at the upper 4 layers. At last, at the location higher than layer elevation of 7.0m, set steel tubular pile (or called steel pipe pile) as support foot right near the driving-hole of sheet piles.