Geoscience Reference
In-Depth Information
reinforcement, reinforcing the base of the higher embankment. Such reinforcement
assists in preventing a number of forms of failure, including lateral spreading and the
normal circular arc. Case histories are given in Rowe and Mylleville (1996) and Farrell
(1997).
The geotextile may also be an aid to construction. On a wet site it helps with the
establishment of an initial working platform, and in more fibrous peat it helps to
preserve the natural surface mat from the destructive activity of the construction traffic.
It should also be noted that the natural fibres of peat are helpful in maintaining the
stability of the fill.
The addition of a bamboo mattress is similar to the use of corduroy. Corduroy
construction involves placing cut trees or planks, often obtained from clearing the site,
at the soil-to-fill interface as a mean of distributing the load and bridging the soft
spots in an organic subsoil. This still represents an excellent method of construction
when timber is available and labour is economically viable to place the timber (Jarrett,
1997).
An example where the replacement and geotextile method was adopted was the
construction of the Kuching Boulevard road project in the proposed new financial
centre of the city (Kuching, Sarawak Malaysia). The site was underlain by some 2-4m
of very soft clayey silt with some decayed wood and peat, with a natural moisture
content of 40-300% and an undrained shear strength of 10-20 kPa, overlying some
2-5m of firm to stiff clayey silt. The superficial deposit was excavated and replaced
with a suitable earth fill. Bamboo mattresses and sandy aggregates separated by non-
woven geotextile were utilized as a separator-cum-drainage layer above the original
ground at the excavated level (Figure 6.6).
An example of a case history where bamboo mattresses were combined with non-
woven geotextile to provide a separation layer on which a working platform could be
A
A
BONDED PIECES OF APP ROVED
ROUND WOOD TO BE TIED
TOGETHER BY STEEL WIRES
REPEAT
REPEAT
REPEAT
MIN.40
φ
MAX 700
MAX 700
SECTION A-A
MAX 700
MAX 700
PLAN OF GEOTEXTILE FASCINE MATTRESS
Figure 6.6
Geotextile fascine mattress (
after
To h
et al
., 1994).
