Foundation and Retention Solutions in Geology Susceptible to Lateral Soil Movements Impacting Sensitive Wharf Structures-PPT Presentation

PPT Presentation

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The project involved foundation and retention works for a development in Melbourne Docklands, beside sensitive wharf and seawall structures. The site’s history and geology—including very soft clays, silt, gravel, and local basalt over clay—created significant risks from pile-installation-induced ground movement.<br /><br />Earlier Docklands projects showed the consequences of excessive lateral movement: timber piles supporting nearby wharves have limited bending capacity, and substantial displacement led to costly repairs. To reduce risk, the project team selected different piling systems for different site areas and agreed on an installation sequence based on previous experience. Work generally progressed from northeast to southwest, installing sheet piles first, followed by predrilled precast piles, CFA piles, and steel tube piles.<br /><br />Sheet piles supported excavation and helped contain soil movement. Predrilled precast piles were used closest to the timber wharf, where minimizing displacement was especially important. CFA piles provided economical capacity for heavy central loads, while open-ended steel tube piles were used near the seawall, where lower bearing requirements and limited soil displacement were advantageous. Basalt tongues were also investigated because of refusal and settlement risks.<br /><br />Inclinometer readings confirmed that installation caused lateral movement in the soft clays, generally toward the wharf or seawall. Some measured movement exceeded finite-element predictions. The design therefore accounted for soil-induced bending as well as structural and earthquake loads, with pile reinforcement extending below the relevant silt interface. Monitoring recorded a peak deflection of 62 mm in a corner core pile, with negligible movement below 23 m.<br /><br />The project’s main lesson is that no single piling method suits all conditions. Combining techniques, carefully controlling installation effects, and providing adequate deep reinforcement helped keep movement within project criteria and protect adjacent structures.

Keywords

Melbourne Docklands

foundation works

retention works

pile installation

soft clays

lateral movement

wharf protection

seawall structures

CFA piles

inclinometer monitoring