Evaluation of K 0 in stiff clay by back-analysis of convergence measurements from unsupported cylindrical cavity

摘要: The coefficient of earth pressure at rest K 0 fine-grained soils is often being estimated empirically from the overconsolidation ratio (OCR). relationships adopted in this estimation, however, assume that caused by pure mechanical unloading and do not consider a significant proportion apparent preconsolidation may be effects ageing, particular secondary compression. In work, Brno Tegel, which clay stiff to hard consistency (apparent vertical 1800 kPa, OCR 7), was based on back-analysis convergence measurements unsupported cylindrical cavity. values were subsequently verified analysing supported exploratory adit two-lane road tunnel. As simulation results are primarily influenced soil anisotropy, it quantified an experimental programme. shear moduli $$\alpha _G$$ 1.45, horizontal Young's _E$$ 1.67, value Poisson $$\nu _{tp}$$ close 0. described using hypoplastic model considering very small strain stiffness anisotropy. For given soil, OCR-based estimation yielded $$K_0=1.3$$ , while Jaky formula $$K_0=0.63$$ for state normal consolidation. back-analysed 0.75. predicted tunnel displacements agreed well with monitoring data, giving additional confidence into selected modelling approach. It concluded equations should used automatically estimation. many clays actually lower than assumed.