Interpretative Framework of a Robotic CPT P-Y Module for Direct In-situ Measurements of Undrained Clay Behaviour
摘要
Current industrial design of offshore single- or multi-pile foundations highlights the critical role of accurately assessing soil properties for the develop-ment of lateral load-displacement (p-y) springs. Conventional CPTs, as one of the most widely used site investigation tools over last 50 years, have been used to infer strength and stiffness parameters for p-y springs, despite the use via em-pirically derived correlations. To improve the speed of site investigation and the data quality for supporting the design of laterally loaded piles, the ongoing col-laborative research project ‘ROBOCONE’ has implemented a robotic cylindrical module that fits in a CPT shaft and is capable of horizontal translation – referred to as p-y module – which allows the soil to be probed through the application of kinematic mechanisms and strain histories. This paper sets out an interpretive framework that showcases how the p-y module can measure directly the key me-chanical properties of undrained clay, i.e., undrained shear strength and elastic shear modulus. A systematic series of finite element analyses were carried out for deriving the lateral bearing and stiffness factors that vary with the roughness of soil-structure interface and the p-y module geometry. These research outcomes also provide a basis for determining the optimal geometry of the p-y module for use in clay.