Variable rate of penetration and dissipation test results in a natural silty soil

Abstract

Variable rate of penetration over 1.2 to 1.5 m intervals were carried out in a natural clayey silt followed by dissipation tests. The tests are grouped into two main sets: an upper set from 5 to 6.5 m and a deeper set from 8.5 to 10.2 m. Index, strength and consolidation parameters are presented for reference to soil behavior and classification. This paper investigates the effect of rate on u2, qt and Bq using penetration rates of 2, 20, 100 and 320 mm/s. Similarly the effect of rate was investigated for assessment of dissipation tests and estimation of the time for 50% dissipation (t50). Dissipation tests were predominantly dilatory at all rates and depths. Drainage conditions were evaluated at the different rates using the normalised rate of penetration (V) calculated using one method to estimate the horizontal coefficient of consolidation (ch). Reference to Bq as a guide of drainage conditions is discussed together with V. A total of six methods to estimate t50 and subsequently ch were used in this study, calculated t50 values are presented for all methods. One method is used for presentation of trends and consideration of which methods may yield the most representative ch values is discussed in relation to laboratory cv.

Variable rate of penetration and dissipation test results in a natural silty soil