AN APPROACH FOR ESTIMATING DEFORMATION MODULI FROM SELF-BORING PRESSUREMETER TEST DATA

Abstract

During a self-boring pressuremeter test (SBPMT) a cylindrical cavity is expanded from a finite radius. To determine undrained shear strength, C_u, of a saturated clay, SBPMT data is analyzed using the cylindrical cavity expansion theory, and curve fitting methods. At present, there is no completely consistent and reliable method to estimate the value of modulus of elasticity. In this paper, an alternative method has been presented to first estimate C_u and limit pressure, P_L, using a logarithmic model and then determine initial tangent modulus, E_i, secant modulus at failure, E_sf, and secant modulus at half the value of (σ₁-σ₃)_f, E₅₀, using a hyperbolic-model. Values of C_u determined from this method compare well with those determined from other methods. The predicted values of E_i and E₅₀ compare well with those determined from the triaxial tests. The values of E₅₀ also compare well with the values of modulus determined from unload-reload cycle of SBPMT.