Investigation on the Thermal Conductivity of Shanghai Soft Clay

Investigation on thermal properties of Shanghai soft clay is of great importance for the design of subway fire safety in Shanghai. Using the heat probe method, thermal conductivity tests were conducted on the remolded specimens of the silty clays from the (4) and (3)(-1) layers in Shanghai. Results show that the thermal conductivity of saturated Shanghai soft soil decreases with the increase of void ratio. For given void ratios, the thermal conductivity of saturated Shanghai soft clay increases with increasing temperature, while the increasing rate depends on the temperature. For constant void ratio, with increasing water content, the thermal conductivity of Shanghai clay increases first and then turns to decrease with a maximum value appearing close to the water content corresponding to the plasticity limit of the soil tested. This observation may be due to the shrinkage of the specimen, which induces the decrease of the void ratio resulting in closer contact of soil particles.