As a sediment control facility, sabo dam has to prevent erosions, to
stabilize the riverbank, to reduce the velocity of debris flow, and to store the flow
of sediment. Recently, sabo dam is not only intended to control the sediment but
also to be utilized as connection bridge.
To design sabo dam, it has to be taken into account the stability of the dam
beside its structural - strength. The stability analysis of sabo should be done in 3
points as stability analysis includes stability against overturning and tensile stress,
sliding of the base and bearing capacity of ground. To do so, it is considered three
conditions. The first is normal condition, the second is the condition when the
flood taken place, and the third is when the debris flow happen. As a road bridge,
sabo dam will receive significant traffic load therefore the strength of the slab
must be analyzed. The standard design used was RSNI T-02-2005 “Pembebanan
untuk Jembatan”, and structural analysis used was SAP2000 software.
The results indicated that the safety factor for stability against overturning
and tensile stress is 7,95 and 6,19 that is larger than the suggested safety factor
(Sf),1,5 therefore the sabo dam is safe for overturning moment and tensile stress.
The safety factor for sliding was a 2,64 and 2,33 that is also larger than suggested
safety factor 2,0, then the structure is also safe against sliding. Based on three
conditions : normal, flood and debris flow, the calculated maximum stress
( ) were 27,40 t/m2, 29,72 t/m2 and 29,28 t/m2, those are less than allowable
bearing capacity of soil under the base of the dam 60 t/m2. The result of concrete slab
analysis indicated that the area of reinforced bar is 3166,67 mm2 that is more than
existing structure using longitudinal bar D16-200 (1005,31 mm2), it means that
the slab is not strong enough to resist the load according to RSNI T-02-2005
having the truck load of 50 ton. Suggested maximum vehicle load is 8 ton that
results the reinforced area 988,97 mm