Comparison coefficient of consolidation from CPTu and one- dimensional consolidation Tests

Coefficient of consolidation (CV) is one of the important parameters used in geotechnical design. This parameter is usually achieved from one dimensional consolidation test in laboratory. Cone penetration Test (CPT) is an in situ test, in this test can be measure pore water pressure with time this test has previously been introducing dissipation test. Teh (1987), Houlsby and Teh (1988), Teh and Houlsby (1991) and Jones and Rust (1995) have been proposed different methods to determine CV from CPTu results. In this paper, have been used 43 dissipation tests and 35 one dimension laboratory consolidation tests that were conducted in three areas in southern Iran and are compared CV are obtained from CPTu test by from 4 methods listed above with each other’s and one dimensional laboratory consolidation test. The results show that CV obtained from laboratory test is higher than the value obtained by from Teh & Houlsby (1991) method and lower than the value obtained from others methods. The similarity of results obtained from laboratory test in terms of amount and trend are closer to results obtained from Teh & Houlsby (1991) method. The empirical relationships between laboratory and in situ CV are proposed. For all equations, coefficient of correlation is higher than 0.7. The highest value is belong to Houlsby & Teh (1988) method and the least value is belong to the Jones & Rust (1995) method.
Once the empirical equation is proposed for each site indecently, coefficient of correlation in all methods is high but while the empirical equation is proposed for all sites together coefficient of correlation is decrease. Thus these empirical equations are influenced by the characteristics of each area so for each area must be independently evaluated and empirical equation are proposed.