Page 22 - Landscape SA 102

ALLIED TRADE FEATURE

Terraforce L11 wall and 4 x4 steps to
research, development and introducing free-loading from original marketing access an upper garden terrace
innovative products to the market. This material. This relaxed attitude is clearly
is time-consuming so they find it easier affecting the quality of design and
to just 'copy and paste', passing off their installation as well, hence the need for
counterfeit products as genuine, or even articles on the safety of retaining walls. LSA

Reasons for wall failures lateral earth pressure or poor quality
of blocks.
Some years ago, Terraforce compiled a
catalogue of wall failures and their causes, Sometimes a combination of causes
which was later adopted by the Concrete may be the trigger for these shortfalls.
Manufacturing Association of South Africa. According to Sean Dowds of Mondo
These shortfalls are: Civils, the most common failures in
• insufficient constructed mass and block retaining walls are bulging,
negligible design input; horizontal (sliding) movement, rotation
• saturated backfill – lack of drainage (overturning), settlement of the whole
above or behind the wall; wall, shear (sliding between the blocks)
• design angle and height exceeded – and global slope instability, where the
lack of supervision; whole slope collapses.
• excavation too close to wall foundations;
• excessive loading – not accounted for There are very few sudden failures in block
in the original design; walls. Most failed walls will give obvious
• limited bearing capacity – poor or clues that something has gone wrong, and
saturated founding conditions or no it’s important not to ignore these when
foundation at all; they become noticeable.
• poor connection between blocks and
geogrid; Photos courtesy of Remacon, Terraforce
• linear cracking of blocks – excessive and Mondo Civils

20 Landscape SA • Issue 102 2021