ADAPTIVE DESIGN AND CONTRACTUAL APPROACHES TO ADDRESS GEOTECHNICAL UNCERTAINTIES IN A DESIGN-BUILD GROUND IMPROVEMENT PROJECT

摘要

During the procurement phase of a Design-Build (DB) project, design-build contractors must oftencommit to a fixed price based on limited or incomplete geotechnical information. This lack ofinformation can result in an inaccurate assessment and allocation of project risk to either the contractingauthority or the DB contractor. This paper presents a case study of an elevated water tank supported bymixed ground improvement techniques, including Vibro-Compaction (VC), Aggregate Piers (AP) andCompaction Grouting (CG) in East St. Louis, Illinois. An adaptive design and contracting approachprovided the best value solution for a complicated set of geotechnical problems, including static bearingcapacity and settlement concerns as well as liquefaction induced settlement. Close cooperation betweenthe owner, the tank contractor, the geotechnical engineer and the ground improvement contractor wasessential to produce an effective solution. Ground Improvement techniques resolved the geotechnicalchallenges at the site through adaptive design methods, utilizing progressive rounds of verification andreal time data acquisition to achieve performance objectives. This paper details the evaluation ofgeotechnical criteria, the selection of ground improvement techniques, the adaptive design andimplementation of ground improvements, as well as contracting methodologies used to ensure that thebest value was provided.