Abstract
This paper investigates the fracturing phenomena in sandy as well as cohesive soil caused by injecting viscous materials such as the mortar. The fracturing pressure generally increases as the flow value F of injection material increases. In cohesive soils, the fracturing pressure Pf is equal to the cavity expansion pressure Pu (Vesic, 1972)of cohesive soils, irrespective of the value of F when F is more than 30 sec. This is because it is more difficult to mobilize the wedge action as the viscosity of injection materials increases. On the other hand, in sandy soils, the effect of flow value F on the fracturing pressure Pf becomes smaller as the permeability of sand increases. The fracturing pressure Pf' of sand of high permeability is equal to the cavity expansion pressure Pu' of sand soil, irrespective of the value of F.
