SUBSOIL IMPROVEMENT METHOD

PURPOSE:To release an expansion stress generated in a subsoil in a chemical by installing a continuous wall-shaped ditch on a specified subsoil and implanting a chemical whose uniaxial compressive strength during freezing time is lower than the freezing strength of an original subsoil and freezing the subsoil. CONSTITUTION:When constructing a continuous wall-shaped ditch which is opposed to the peripheral parts of an existing structure, the subsoil is excavated by using a stabilizer liquid which is designed to prevent the collapse of earth and sand from a wall surface. A chemical is used, which is like a solution when it is transferred into the ditch and when it is replaced with the stabilizer liquid and after a fixed time lapsed, the chemical gradually increases the viscosity while it becomes further gluey. What is more, it is necessary to select a replaced subsoil whose uniaxial compressive strength during freezing is lower than the freezing strength of an original subsoil. An equally mixed solution preliminarily adjusted with a sodium silicate solution and a reaction agent is transferred into the ditch by way of a single pipe or a multiple pipe and fed into the subsoil replacing with the stabilizer solution. Then, a freezing process is applied to a specified subsoil, thereby solidifying the excavated subsoil.