Methodology for Obtaining Optimal Sleeve Friction and Friction Ratio Estimates from CPT Data

Cone penetration testing (CPT) is a cost effective and popular tool for geotechnical site characterization. CPT consists of pushing at constant rate an electronic penetrometer into penetrable soils recording cone bearing (qc), sleeve friction (fc) dynamic pore pressure (u) with depth. The measured qc, fs u values are utilized to estimate soil type associated properties. A method from measurements the Soil Behavior Type (SBT) chart. SBT plots resistance vs ratio, Rf [where: = (fs/qc)100%]. There distortions in which can result erroneous plots. specific depth blurred or averaged due qc being strongly influenced by within 10 30 diameters tip. qcHMM algorithm was developed address blurring/averaging limitation. This paper describes occur when obtaining association blurring significant errors calculated values. outlines novel highly accurate ratio estimates. fc optimal filter estimation technique referred as OSFE-IFM algorithm. mathematical details outlined this along results challenging test bed simulation. simulation demonstrates that derives estimates Optimal subsequent behavior type.