Excavatability in Caliche Soils in Arizona: Comparison of Owner and Contractor Perspectives

摘要

Cemented soils, commonly called caliche in the Southwestern United States, are frequently encountered in excavations conducted in the Phoenix metropolitan area. Heavily cemented materials of extremely high strength and stiffness are not frequently encountered, but do occur. Excavations which must penetrate such materials can be very difficult and expensive to complete. Because these materials are spatially heterogenous, they are often missed in geotechnical characterization for an excavation project, and so disputes and conflicts between owners and contractors during the progress of the excavation sometimes arise. This paper reports an evaluation of the difficulties posed by caliche for bidding and contracting in this environment. A series of interviews was conducted with representatives of owners and contractors to obtain information about the adequacy and use of existing characterization technologies, the bidding and contracting strategies favored when cemented soils are potentially present at the site, and the likely dispute progression should changed conditions be encountered. Commonly used contract language is described, along with the bidding implications of this language. Striking differences between owner and contractor perceptions were noted, especially with regard to the adequacy of investigations commonly conducted and the likely behavior of a contractor when provided with additional information.