ANALYSIS OF THE UNDRAINED SHEAR STRENGTH THROUGH THE STANDARD PENETRATION TEST WITH TORQUE (SPT-T)

Abstract

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/NSPT and soil structure found elsewhere in the world and investigates whether parameters
governing the undrained condition of soil may be correlated with T/NSPT. 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/NSPT parameter used in
analyses of this test.