Finite element analysis of self-boring pressuremeter tests in clay

Abstract

Self-boring pressuremeter (SBPM) tests are widely used in site investigations, due to their distinct advantage to measure the shear stress-strain-strength properties of the surounding soil with minimum disturbance. The measured pressuremeter curve can be interpreted using analytical solutions based on the long cylindrical cavity expansion theory with relatively simple constitutive models. However, SBPM tests are strongly affected by the soil behavior and details of installation procedure. In addition, the derived parameters for clays (e.g. undrained shear strength, and shear modulus) are affected by a number of state variables such as overconsolidation ratio, and stress level. In this paper, SBPM tests are investigated using finite element analysis and the MIT-S1 model, to consider complex soil behavior more realistically. SBPM tests in K0-consolidated Boston Blue Clay at different OCRs are simulated in axial symmetric and plain strain conditions, consistent with the assumptions used in analytical solutions. The derived undrained shear strength from both contraction and expansion curves are compared with theoretical values from stress-strain curves, to evaluate the reliability of the derived parameters from the SBPM tests.