qc/N Ratio for Recently Deposited Crushable Soils

Abstract

The SPT and CPT are often used interchangeably as quality control tests for many reclamation improvement projects. Geotechnical specifications for crushable (commonly referred to as calcareous) in soil reclamation projects usually adopt typical common relationships for the (qc/N) ratio to allow using one or the other of the two tests as quality control tools. Specifying (qc) and/or (N) target values interchangeably requires an assessment of the ratio (qc/N) that is particular to the soil being tested. However, most such available relationships are based on databases of siliceous soils. The ratio (qc/N) for recently deposited crushable soils forms a knowledge gap that frequently inhibits achieving the needed consistency when specifying acceptance values for the quality control works of many mega projects. This gap subsequently opens the door for unwarranted, costly and time consuming disputes between the geotechnical consultants and the contractors. In this paper, correlations for (qc/N) are developed using high quality data that were obtained for crushable soil reclamations in the Arabian Gulf. Different correlations were envisaged to enhance the accuracy in a progressive way to correlate CPT and SPT readings using both the mean soil diameter (D50), the Soil Behavior Type Index (Ic).