Rational determination of cone penetration test quantity in a two-dimensional vertical cross-section for site investigation

Abstract

Site investigation plays a critical role in underground space development and geotechnical engineering practice, and it aims at collecting data for characterization of subsurface soil properties and stratification, which are often simplified as a two-dimensional (2D) vertical cross-section for subsequent geotechnical design and analysis in practice. In-situ tests, such as cone penetration tests (CPT), are often performed during site investigation. Existing tunneling or geotechnical guidelines or design codes only provide conceptual principle for determination of CPT quantity (e.g., accuracy of site investigation improves as the CPT quantity increases) and recommend some rule-of-thumb minimal quantities (e.g., at least one CPT every 100 m). No rational method is available to determine the minimal CPT quantity for achieving a target level of accuracy in an objective and quantitative manner. This paper aims to develop a rational method for addressing this issue. The method developed is based on an extensive parametric study that uses random field simulation to cover typical CPT data encountered in geotechnical engineering practice and Bayesian compressive sampling to interpolate the spatially varying, but correlated, CPT data along both depth and horizontal directions simultaneously. The proposed method is illustrated and validated using real CPT data, and it is shown to perform well.