In recent years, the study of the thermo-hydro-mechanical behaviour of soils has been a growing area within the geotechnical community due to its importance to a wide range of civil engineering applications and activities which involve the ground as a heat source, sink or medium for heat storage. This thesis reports an experimental study of the thermo-mechanical behaviour and thermal properties of London clay and is structured in three blocks as follows.
The first part of the thesis describes the development of new experimental capabilities in the Imperial College Geotechnics Laboratory and the methodology of the thermo-mechanical and thermal properties tests. A new temperature-controlled apparatus capable of testing saturated soils at pressures up to 800 kPa and temperatures ranging from ambient to 85 ºC is presented. The thermal performance of the cell is thoroughly assessed, as well as the calibration of the different components. Furthermore, the use of needle techniques, single and dual probe, for the measurement of the thermal properties of soils is investigated.
The second part reports a laboratory programme of thermo-mechanical tests on reconstituted London clay samples. The thermally-induced volumetric strains during drained heating and cooling cycles in samples with different stress histories are investigated, showing similitudes and discrepancies with other clays. The nature of the measurement of thermal deformations in this study, as well as on published work, is discussed in detail. Moreover, the temperature effects on the compression behaviour, strength and stiffness of the material are also investigated.
Finally, the measurements of the thermal properties (thermal conductivity, diffusivity and volumetric heat capacity) performed on reconstituted and intact London clay samples using the single needle and dual-probe heat-pulse tests are presented, discussing the influence of the state and nature of the sample (porosity, water content, mineralogy), direction of measurement and the appropriateness of the instruments used.