Analysis of the undrained shear strength through the standard Penetration Test with Torque (Spt-T)

Although in situ tests are very useful for obtaining data on the strength and deformation of a geomaterial, some of these tests have been criticized because of their limitations for identifying certain parameters. This paper presents research into a hitherto little used test here in Colombia, the SPT-T (Standard Penetration Test + Torque). This test combines the advantages of the Standard Penetration Test (SPT) and the Vane Shear Test (VST) to obtain a soil's lateral friction and to correlate its classification and structure by means of the relationship between the NSPT and the torque applied. This study reaffirms the dependent relation between T/N_SPT and soil structure found elsewhere in the world and investigates whether parameters governing the undrained condition of soil may be correlated with T/N_SPT. Conceptually, a relationship between undrained soil conditions and the way the test is conducted is evidenced. For this reason, this research is an initial approach which open the door to continuing phases of research that may be able to develop appropriate correlations between undrained strengths of soft soils and the T/N_SPT parameter used in analyses of this test.