Fabric and Geotechnical behavior of the volcanic clays of Xalapa, Mexico

The City of Xalapa is nailed in the Eastern part of the Axis Mexican Neovolcanico and is laid the foundations, in its majority, clays of volcanic origin of the Quaternary. These ashes have a peculiar behavior when the micro climate around them varies, as shown in previous slides of the slope and embankments. On the other hand, these clays problems for their identification, as these soils are rich in halloysite and to a lesser extent by allophones. To understand the microstructure in natural state of the clay one studies the characteristics physical-chemistries of his components by the method of ionic chromatography and the chemical isolated particle composition is analysed with an transmission electron microscope (TEM) with a connected detector of dispersion of X-ray energy. On the other hand, the mineralogical composition is obtained from X-ray diffractometer of dust in argillaceous fraction. The morphology of particles is identified by means of the TEM. Limits liquid associated with the specific surface of particles, this last one determined by adsorption of N2. The fabric of the clay in natural and artificial state (with different methods from compaction) in the scanning electron microscope (SEM) is compared. In accordance with the above-mentioned, it is studied the levels of the fabric, the morphology of the pores and the type of connections of the particles. In order to verify the hypothesis that the mechanical properties of the soil depend on the fabric of this artificial and natural samples prepared and geotechnical behavior is characterized to observe its answer and to compare it. Also it is observed as it influences the fabric in the deformation of this one under constant suction. The residual strength is investigated carefully and it is compared with that of the peak. (Author) 35 refs