Investigation of the stake tilt with clay soil condition for capacity of pump house foundation structure

Bendung watershed is Palembang’s drainage system covering 15.4 km2 which the main river’s length is 5.4 km. The Bendung river’s primary drainage system drains into the Musi river. The Bendung watershed has an average land elevation of 2.0 m to 18.0 m above sea level. A flood control building was built to accelerate Bendung Watershed’s flow to reduce flood. As a result, a Pump House in the Bendung River was required, equipped with retention ponds and automatic floodgates. The pump house structure is designed to load six pumps (each weighing 14 tons), with a total weight of 84 tons before operation. The foundation work in the field resulted in soil movement (clay conditions), causing the stake that had been embedded to be displaced from its original coordinates (tilted) or damaged. Based on PIT (Pile IntegrityTest), the stake in an oblique condition (damaged) at 10 m depth from 24 m of the plan depth, resulting in reduced foundation support in the load of the pump house structure. Therefore, a review of the modelling of the limitation of the upper structure was conducted, referring to the value of the requirements displacement permit structure to the foundation’s carrying capacity. As a result, obtain an alternative design of the spun pile condition to add a mini pile depth of 16 m and dimension pile 40 cm with a group pile and pile cap using the STAADPro software approach.