Methods for forming supported cavities by surface cooling

Abstract

This invention relates to the formation of cooled or frozen zones of soil or other granular material using low temperature fluids introduced to contact the material through a cavity forming tool which aids in cavity support until such time as the required cooling or freezing occurs. The coolant may be introduced into the cavity under pressure in a manner to provide intermediate cavity support during the tool withdrawal process, such pressure being retained in the formed cavity by virtue of the tool and material forming an effective seal to minimize inadvertent loss or venting of coolant to the atmosphere. As such, the cavities can be formed in any desired orientation, depending upon the direction of tool insertion. It is to be recognized that the introduction of coolant under pressure is not a requirement of the invention where the coolant has characteristics which will induce the necessary flow into the cavity. The material in which the cavity is formed under the invention must contain a congelative fluid, which may exist prior to the insertion of the cavity forming tool or which may be introduced as part of the process of tool insertion and cavity formation. Therefor, the present invention permits application to soils and material which heretofore could not be rendered self-supporting by virtue of the lack of suitable congelative fluid in its granular materix. The invention is capable of being practiced to produce a cooled zone which increases in thicknesses with depth so as to develop the required strengths to resist the cavity destabilizing forces which normally increase with depth. Such cavities formed as a result of practicing the invention may be utilized for the installation of support piling of all types, as the required support material can be introduced directly into the cavity by virtue of the cavity being rendered self-supporting to thereby remain open during the introduction of the selected support systems. Such cavities may be backfilled with materials and instrumentation of all types in a manner similar to placing support piling. Subsequent thawing of the congealed cavity periphery would permit the use of devices to either extract flowing fluid from the material, or the control of fluid levels in the material either by introducing or removal of desired fluid.

Dependencies are inferred from the claim text.