Evaluation of coefficient of consolidation for dilatory dissipation in piezocone test in overconsolidated cohesive soils

Pore pressures induced by piezocone penetration

“…The outcome of the dissipation test is a dissipation curve of u 2 , which can be used to determine the coefficient of consolidation in the horizontal direction (c h ) of the soil stratum at the test depth. Numerous research studies have been published on this aspect of piezocone testing (Teh and Houlsby 1991;Chai et al 2012a;Ansari et al 2014;Mahmoodzadeh et al 2014;Ha et al 2015;Krage et al 2015). There are also researches on using dissipation test results to estimate the undrained shear strength of the deposit (Mantaras et al 2015) Two types of piezocone dissipation curves have been reported in the literature.…”

“…There are also researches on using dissipation test results to estimate the undrained shear strength of the deposit (Mantaras et al 2015) Two types of piezocone dissipation curves have been reported in the literature. One displays monotonic reduction of the measured values of u 2 with time (e.g., Teh and Houlsby 1991), i.e., the so called "standard" dissipation curve; and the other is a "non-standard" curve, for which the measured value of u 2 increases initially and then reduces with time (Burns and Mayne 1998;Sully et al 1999;Chai et al 2012a;Ha et al 2015). Some results of numerical simulation (e.g., Chai et al 2012a) and laboratory testing (Kim et al 2007;Chai et al 2014) have suggested that the reason for a non-standard dissipation curve is that at the beginning of the dissipation the pore water pressure at the filter element induced by cone penetration is lower than the pore pressures generated in the soil nearby.…”