Abstract: : : :An experimental embankment was constructed in Rouen, France. The construction was completed in December 2004. The first objective of this experiment is to investigate the influence of climatic changes on the soil response such as changes in water content and temperature as well as the induced vertical and horizontal displacements; and the second objective is to investigate the soil response under water flooding from the base of embankment. In this study, the changes in temperature, volumetric water content and suction along the central axis have been analysed using a one-dimensional model and based on the meteorological data obtained in the field.Comparisons made between the measurements and simulations have shown the relevance of the method adopted, provided that suitable boundary conditions and soil parameters are taken into consideration. Moreover, both the simulation and field monitoring showed that climatic effects are limited to a shallow depth, which results from the low permeability of the compacted fill.
The effect of different specimen preparation methods (compaction, reconstitution) on the hydromechanical behaviour and microstructure of soil was studied through a series of soil-water retention tests, triaxial tests, and mercury intrusion porosimetry (MIP) tests on an unsaturated clayey silt. Key findings from this experimental study include the following. (i) The air-entry value of the reconstituted specimen is higher than that of the compacted specimen with the same initial void ratio. (ii) The reconstituted specimen exhibits a unimodal pore-size distribution and the compacted specimen exhibits a bimodal pore-size distribution, according to results of the MIP tests. (iii) The soil-water characteristic curves and residual gravimetric water content of compacted and reconstituted specimens are almost the same in the high suction range. (iv) The void ratio of a reconstituted specimen decreases sharply with increasing suction value under an isotropic net stress (such as 20 kPa), while the void ratio of a compacted specimen shows a small change for the same suction change process. (v) Under the same net confining pressure, the shear strength of both compacted and reconstituted specimens increases with the suction increase. The shear strength of the reconstituted specimen is higher than that of the compacted specimen with the same density under the same suction and net confining pressure.
To investigate the soil-water retention curves of undisturbed and compacted lateritic clay specimens in the full suction range, suction is imposed or measured by using the pressure plate method, filter paper and vapor equilibrium technique with a saturated salt solution. The mercury intrusion porosimetry (MIP) tests were also performed to observe the pore size distribution (PSD) of undisturbed and compacted samples. The test results show that the undisturbed samples have lower gravimetric water content and degree of saturation than the compacted samples at the same density in the suction ranging from 0 kPa to 10 MPa. According to the study on microstructures, the observed phenomenon can be explained by internal cracks of undisturbed samples continuing to develop along with an increase in suction. When the suction is higher than 10 MPa, the soil-water retention curves (SWRCs) coincide with each other for both undisturbed and compacted samples. Undisturbed samples exhibit a unimodal PSD, while unsaturated, compacted samples have a distinct bimodal PSD. The structural degradation of the clay aggregate due to the moisture change leads to the change of the interaggregate pores (the intra-aggregate pores remain almost unchanged). For unsaturated, compacted samples with different void ratios, the intra-aggregate PSDs are almost the same, while the inter-aggregate PSD varies with the void ratio. This can be adopted to explain that the wetting branches of the SWRCs are independent of the dry density in the high suction range when the SWRC is expressed by the relation between suction and gravimetric water content. The results of MIP tests on a saturated sample are used to predict the SWRC of the same soil in the main drying.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.