This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
To guard against this, the banks or sides of the excavation are sheet piled, as shown in Fig. 1.
Sheet piling consists of a plank cut to a point at the lower end, placed closely in line, and driven into the ground against the bank of the excavation, as shown at (a), Fig. 1, which is a front elevation of sheet piling. At a is shown the piling driven into the cellar bottom b, against the bank of the excavation. At (b) is a section across the piling to show the braces d placed against the batten e to retain the piling in place against the earth pressure at the top. The stake shown at f is driven in to keep the brace d from slipping. These braces are usually spaced about 10 or 12 feet apart, and are necessary when the excavation is a deep one.
26. When the foundations of a new building go below those of the adjoining property, the adjacent walls must be underpinned, the method of doing which, will be described in a subsequent section.