The undrained remoulded shear strength of a clay, s_ur, is an important parameter in the design of a number of geotechnical applications. In the case of onshore tests the value of s_ur is generally obtained from vane tests. Recently, cyclic T-bar tests have been used to obtain the s_ur value, especially for offshore applications. Seventeen T-bar cyclic tests in two deployments have been performed at Sarapuí­ II soft clay test site. In a third deployment only penetration was recorded. The presence of roots has influenced the values of the initial penetration in one of the deployments, as observed in another test site, which is a consequence of the shape of the penetrometer and may be considered a shortcoming of the test. Therefore, to know whether roots have influenced the test results in a site at least two repeatable tests must be performed. If cyclic tests are performed, their results can provide a good indication of the influence of the roots. Considering the vane shear test as reference for obtaining su and s_ur, N_T-bar obtained from tests not affected by the roots ranged from 8.8 to 10.9, with an average of 9.8, while N_{rem, T-bar} ranged from 14.1 to 19.5, with an average of 16.3. Therefore N_T-bar values (related to the natural condition) were smaller than N_{rem, T-bar} (related to the remoulded condition). The equations suggested by Yafrate et al. (2009) to evaluate the remoulded penetration resistance, the whole degradation curve and the sensitivity, based only on the initial penetration and extraction resistances have provided good results for the Sarapuí­ II soft clay, except in the case of very shallow depths.

Keywords: In situ testing, Soft clay, T-bar, Undrained shear strength, Remoulded undrained shear strength, Sensitivity,

Submitted on October 31, 2011.
Final Acceptance on November 21, 2012.
Discussion open until April 30, 2013.
DOI: 10.28927/SR.353279