Pre-loading of soft Holocene materials adjacent to shallow founded structure

This paper describes a case study in Fiji involving the use of pre-loading to accelerate primary consolidation settlement prior to constructing buildings over soft Holocene materials. The pre-loading involved placing a surcharge exceeding the weight of the future structures. Careful monitoring took place to ensure the settlement exceeded the expected settlement which the weight of the structures would induce. Sufficient time was available to achieve the settlement without the need or expense to construct vertical drains to otherwise speed up settlement.

The site history and geology are discussed with respect to settlement inducing layers. Previous works on the site involving cutting and filling resulted in a complex stress history requiring careful evaluation of the effects on settlement.

The shape of the pre-load was designed to achieve the settlement requirements for the proposed buildings without exceeding the differential settlement criteria for the adjacent existing structure. Settlement results demonstrate that the design requirements were achieved.