Influence of barometric pressure changes on slope stability - Measurements and geotechnical interpretations

摘要

For measurements of pore water pressure and their geotechnical interpretation the fact needs to be acknowledged that changes of barometric air pressure play an important role concerning soil behaviour especially in low permeable soils. A connection between falling barometric pressure and landslide triggering in unstable slopes is shown. Open gauge and absolute pressure datum transducers are compared in regard to obtain the correct pore pressure from instrument readings and using the evaluated measurements in slope stability analysis. Possible improvements in the technical instrumentation layout are suggested. To explain unsaturated soil conditions in ground water (below the piezometric line) a three-phase-model consisting of gas, water and soil particles is applied: The compressibility of the pore fluid in a submerged subsoil is to a great extent directly dependent on a small but not negligible quantity of microscopic gas bubbles, which are always present in ntural pore water. Excess pore water pressure may occur, leading to slope failure.