METHOD FOR FREEZING AND SAMPLING SOIL QUALITY SAMPLE IN SHALLOW LAYER

摘要

PURPOSE:To make possible the drawing of a soil quality sample in a shallow layer only by as much as needed from the region where the sample is not disturbed and to reduce the size of a machine for boring by supplying a refrigerant through an inside freezing pipe which is insulated of heat up to the upper limit of the sample drawing depth on the outside periphery so that the outside peripheral ground of an outside freezing pipe is frozen to the required depth. CONSTITUTION:A hole is first bored down to the prescribed depth in the ground to be sampled, then the outside freezing pipe 2 and inside freezing pipe 3 are installed thereon. A heat insulating pipe 4 arriving at the upper limit position D1 of the sample drawing depth D is inserted to the outside periphery of the inside pipe 3. The refriger ant such as liquid nitrogen or mixture composed of ethanol and dry ice is supplied through the inside pipe 3 to freeze the outside peripheral ground of the outside pipe down to the required thickness. A hole 5 arriving at the tope end position of the frozen soil (a) is then bored toward the soil (a) in parallel approximately with the pipe 2 and a double-cored bue 11 is inserted through the hole 5 to core and cut the coil (a) down to the non-frozen part, by which the core sampling is executed. The tube 11 is thereafter pulled upon to the ground.