This work presents the development of a new cylindrical calibration chamber constructed at ETH Zurich (ETHZ) to test a novel self-boring probe for in-situ ground investigation, currently under development at ETHZ. The design of the chamber builds up on existing similar concepts for penetration testing, while adopting bespoke solutions for the needs of the self-boring probe. Initially, the chamber is used for proof-of-concept testing of an anchoring unit, which is part of the self-boring probes mobility system. The inner dimensions of the chamber are 730 mm in height and 670 mm in diameter. Either zero-displacement or constant-stress conditions can be imposed along the lateral boundaries of the soil specimen. In the first case, the lateral boundary is the rigid wall of the calibration chamber, whereas in the second case, water pressure acts on a custom-made rubber membrane around the circumference of the soil, controlling the radial stress. Vertical stress is applied through a pneumatic cushion at the base of the chamber, while the top is restricted from movement. The chamber is equipped with central circular openings at the top and base plate. Through these the self-boring probe can be mounted to test its anchoring system and furthermore in a later testing stage, it can be pushed axially without tip-resistance interference in order to estimate exclusively the anchor capabilities. A bespoke pluviation system was developed to fill the chamber with sand. The paper discusses the development of the chamber, sample preparation and test procedure, presenting indicative preliminary results of anchoring unit tests in dry Perth sand.
5th European Conference on Physical Modelling in Geotechnics (ECPMG2024)
New facilities, new equipment, measuring techniques