years is Hos ¼ 1.50 m, and Tm¼ 4 s, where Hos is offshore significant
wave height and Tm is meanwave period. Utilising the same armour
size for all parts of the structure (i.e. trunk slopes, crest, and
roundheads) the armour layer was designed according to Kramer
and Burcharth (2003), based on the initiation of damage. A grading
D85/D15 < 2 was selected for armour stones as suggested by Van der
Meer et al. (1996).
The site is covered by soft mud deposits which makes
construction process very difficult, costly, and impractical because
the unconsolidated upper layer of mud has very low shear strength.
Since this study aimed to focus on practical low-cost methods
suitable for local communities and authorities, local construction
materials which can be inexpensively provided in bulk were
considered together with simple techniques of construction.
Therefore, bamboo stems which are strong, lightweight and
durable were used as foundation mat. The average oven-dry
density of bamboo stems was 557.3 kgm3, with an average
diameter of 8–10 cm and a wall thickness of 0.8–1.2 cm. The stems
were cut into 3 m lengths and tied together by ropes to form the
mats substituted for the foundation. Since the firmly tied stems