This book presents the results of novel hydro-mechanical laboratory experiments on several natural Boom clay samples, using simultaneously mineralogical, microscopic and mechanical techniques. It illustrates the research output through a series of tests, theories, back analyses, and numerical simulations. Based on these experimental results, it establishes a relatively complete theoretical system including elasto-plastic damage constitutive models, creep damage models and permeability sealing models. Further, it includes numerous reliable parameters obtained from back analysis on field stress, anisotropic permeability and in situ creep measurements of high acceptance di-electron spectrometer (HADES). Lastly, using numerical simulation it provides a long-term stability analysis of HADES underground facility.