Method and apparatus for measurement of in-situ horizontal stress of non-coherent soil.

摘要

A high quality frozen core sample 5 of a non-coherent soil such as sand or gravel is covered in a rubber membrane 6 and mounted on pedestal 14 beneath load-exerting cap 13 (to simulate vertical in-situ load at sampling depth) within a pressure chamber with walls 10. Water is filled in to surround the sample. Expansion of the sample 5 on consequent melting is resisted by increasing the air pressure over the water i.e. so as to maintain thegap between float 27 and sensor 28 constant as a measure of water level. The pressure exerted is a measure of the lateral stress on the non-coherent soil. A variant method for field use involves lowering a membrane-covered test member into a frozen borehole and exerting pressure on the walls thereof to prevent dimension change during thawing, the exerted pressure, possibly with a correction for pore water pressure between the soil particles in-situ, being a measure of the lateral stress.