Injection Compositions for Creating Impervious Screen for Roadbed Foundation

Abstract

In order to limit the access of ground waters into the freezing zone and to reduce the value of frost heaving of the road bed soils to the maximum permissible values, the creation of impervious screens by injection method is proposed. Impervious screens are proposed to be made both by "horizontally-inclined" injectors from the slopes and by "vertically-inclined" injectors from the slopes and roadsides, depending on particular soil and hydrological conditions and using different types of injectors. Versatility of the proposed designs of impervious screens and injectors enables the use of various injection solutions and technologies of soil injection (pressure injection, injection in impregnation mode, jet injection, etc.). According to the laboratory research results, exponential dependences of the relative deformation of frost heaving have been established εfr (%) from the relative stabilization height hs/h of the freezing zones. It was established that the average relative strain of frost heave of specimens without stabilization was εfr = 6.2%. Stabilization of this soil with an aqueous solution of sodium silicate (Na2SiO3) enables to reduce the determined index to εfr = 0.7%, with Portland cement (M400) up to εfr = 0.5%, cationic-type surfactants on average up to εfr = 3.6%. The presence in the laboratory sample of an impervious screen in the lower frost zone made of silicified soil or soil stabilized with Portland cement, with a relative thickness of 1/3, reduces the frost heave of the samples to the values εfr = 1.9-3.5%, which is almost half as much as (Na2SiO3) and Portland cement (M400) for the control samples without stabilization. Such additives as an aqueous solution of sodium silicate have shown the greatest effectiveness within the framework of the problem to be solved. The decision to use a stabilizer depends on the specific soil conditions and the injection method and equipment to be used.