Experimental study on the hydro-mechanical behavior of Boom clay

In the context of research into deep nuclear waste disposal, Boom clay, a stiff soil from the Underground Research Laboratory in Mol, Belgium, has been studied in various works. In this paper, containing X-ray diffraction tests, oedometer tests, consolidated undrained shearing (CUS) tests and scanning electron microscopic (SEM) tests, a series of experimental studies intended to study the hydro-mechanical behavior and micro fabric of Boom clay are presented. X-ray diffraction tests and SEM tests further highlight the high content of clay mineral of Boom clay (about 60% in average). Preconsolidation pressure, which is about 5.0 MPa, was determined by oedometer tests. High swelling property under hydro-mechanical coupling effect has been investigated on the clay samples during the CUS test, and also high viscous potential has been represented under shearing rate of 20 μm/min. SEM tests show that the microstructure of Boom clay arranged more directional and denser, and it can be observed clearly through the microstructure variation of pores and fissures.

► Both the X diffraction tests and SEM tests highlight the high content of clay mineral of Boom clay. ► Boom clay has high swelling property under hydro-mechanical coupling effect. ► High viscous potential is investigated under shearing rate of 20 μm/min. ► The theory time needed for Boom clay saturation under in situ stress is discussed. ► Micro structure of Boom clay arranges more directional and denser after tests, and it is also verified by the microstructure variation of pores and fissures.