Impact of temperature variation on pressuremeter test parameters in compacted soils

摘要

In geotechnical engineering, the proper design of thermo-active geostructures (piles, foundations,rnetc.) and deep waste storage disposals requires a better understanding of the thermo-hydro-mechanical behaviourrnof natural and compacted soils. For design purposes, important mechanical parameters of the soils such as thernpressuremeter modulus (E_P), limit pressure (P_l ) and creep pressure (P_f ) are usually obtained by pressuremeterrnin-situ tests. In the present study, pressuremeter tests were conducted in laboratory, using a mini-pressuremeter,rnto characterise compacted soils. The objective was to examine and quantify the influence of temperature changesrnon pressuremeter parameters of two different compacted soils: a clay and a loam. These soils were compactedrnat their optimal water content and 90% of their maximal dry density (standard Proctor) in a thermo-regulatedrnmetric scale container of 800mm in height and 600mm in diameter. The compacted soils were then subjectedrnto a range of temperatures from 20 to 50◦C.rnOnly six tests were performed in each container to prevent edge effects and interaction between the tests.rnThe thermal cycles were applied to the soil massif as following: A heating-cooling cycle (20–40–20◦C) for thernclay; three heating-cooling cycles (20–50◦C) for the loam. Pressuremeter tests were conducted at the end ofrnseveral temperature steps. The obtained results showed a decrease in P_l and P_f with increasing temperaturernfor both tested soils, while the variation of E_P was less significant. Through the temperature range tested, arnquasi-reversibility of the effect of a heating cycle is obtained.