Case History of a Collapsible Soil Fill

by Alan L. Kropp, (M.ASCE), Alan Kropp and Associates, Berkeley, United States,
David J. McMahon, (M.ASCE), Alan Kropp and Associates, Berkeley, United States,
Sandra L. Houston, (M.ASCE), Alan Kropp and Associates, Berkeley, United States,

Document Type: Proceeding Paper

Part of: Vertical and Horizontal Deformations of Foundations and Embankments


Collapse settlement of a deep compacted fill led to damage of a group of condominium units. The fill consisted of a highly heterogeneous mixture of coarse- to fine-grained soil containing angular fragments of gravel- to boulder-sized rock. Compaction specifications requiring 90 percent of the maximum dry density by ASTM method D-1557 were met or exceeded during fill placement, although the fill was generally placed dry of optimum water content, and corrections for rock content were not made in the field. Building distress ranged from mild to severe, depending upon the differential fill thickness beneath the structure. Extensive vertical and horizontal movement monitoring and two full-scale field wetting tests were conducted at the site following the onset of building distress. The results of the field investigations and laboratory response-to-wetting tests provided strong evidence that the building distress patterns were caused primarily by wetting-induced collapse settlement of the deep compacted fill. Based on the results of the field wetting tests, controlled wetting of the site with mud-jacking of the condominium units appears feasible as a mitigation alternative.

Subject Headings: Field tests | Soil settlement | Rock fills | Compacted soils | Fills | Compaction (material) | Buildings

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