ABSTRACT
The phenomenon of hydraulic soil fracturing was initially observed as an undesirable side effect of traditional grouting measures. The uncontrolled propagation of soil fracs that were rapidly lled with grout suspension did not achieve the objective of homogenously lled voids in granular soils. In the past, high pumping rates that no longer allowed the grout to penetrate the pore system of the soil continuously were regarded as a grouting defect. It was crude oil technology using hydraulic soil fracturing for increasing the permeability and thus the yield of oil elds that provided the impetus for systematically applying geotechnical methods for using deliberately produced voids in the soil. In the meantime, fracture grouting has been used for systematically improving soil properties. The load-bearing capacity and permeability of both granular and cohesive soils can be modied by incorporating a cement or solid matter skeleton. The repeated application of this method also allows for the controlled raising of buildings with very different foundation systems. The most spectacular use of the method is found in connection with the complex tasks of compensating for settlements which as a result of tunnel excavation threaten the structural integrity of buildings above the tunnel.
