Abstract
This paper investigates the relationship between the permeability and the dilatancy of sands stabilized by chemical grout under triaxial compression tests.In sands stabilized by silicate grout, the coefficient of permeability k of dense specimens increases from 10-6∼-7 cm/s before shearing to 10-4∼-5 cm/s at failure owing to dilatancy. The deviator stress level when k begins to increase is about 60% of failure strength (maximum deviator stress). The increase of k during shear indicates the failure initiation of cohesive bonds formed by silicate gel ; the cohesive bonds begin to fracture as k increases and most of the cohesive bonds disappear at failure. Therefore, it is suggested that it is the dilatancy phenomenon, rather than the cohosive bonds (i.e. cohesion), which is more deeply related to the failure strength of dense specimens. On the other hand, the changes of k of loose specimens depend upon grain size. The k-value of Toyoura sand specimens, which have a grain size of 0.11∼0. 25 mm, does not increases excessively, because dilatancy (volume expansion) occures only to a small extent. But the k of Soma I and II specimens, both of which have larger grain size than Toyoura sand, increases significantly during shear even when the volumetric strain is negative (contraction).In sands stabilized by acrylamide grout, the permeability is not affected by dilatancy. In practical problems, there would be no necessity for taking into account the change of permeability caused by shear stress increment in the case of this grout.It is concluded that the permeability of sands stabilized by chemical grout may increase remarkably due to flow channels caused by shear stress increment, and that the relationship between the change of permeability and the shear stress increment depends upon density, grain size and the type of chemical grout.
