EXPERIMENTAL STUDY ON THE HYDRO-MECHANICAL COUPLING OF HIGHLY COMPACTED EXPANSIVE CLAY
Highly compacted expansive clays have been usually considered as a possible material for sealing and backfill in deep geological radioactive waste disposal. In this condition, the material is simultaneously subjected to water infiltration from the geological barrier and the stresses generated by the swelling of the engineered barriers in confined conditions. Its behaviour upon hydro-mechanical loading is then essential for the safe design of the whole storage system. In the present work, MX80 bentonite, expansive clay from Wyoming, USA, was studied. After the compaction, its dry density was 1.8 Mg/m3 and its initial suction was 110 MPa. First, the soil was humidified under controlled suction and free swell conditions. Significant swelling was observed. Secondly, isotropic compression tests were performed at constant suction conditions (four values of suction were considered: 110, 39, 9 and 0 MPa). That allowed studying the effect of suction on the mechanical parameters (yield pressure, elastic and plastic compressibility parameters). The results show that the elastic and plastic compressibility parameters increased when the suction decreases. The relationship between these parameters and the logarithm of suction can be correlated with a linear function. The yield stress drastically decreased, upon wetting under free-swell conditions, from 12-18 MPa (at an initial suction of 110 MPa) to 0.2 MPa at saturated state.
Ezpansive clay suction compressibility yield pressure engineered barrier radioactive waste disposal
A.M.Tang Y.J.Cui
Ecole des ponts - ParisTech, UR NA VIER/CERMES, Paris, France
国际会议
上海
英文
71-76
2009-08-24（万方平台首次上网日期，不代表论文的发表时间）