Inclinodeformometer for Earth Pressure Measurements in Creeping Landslides

The inclinodeformometer (IDM) is a novel device for measuring changes in earth pressure in a sliding layer of a creeping landslide. The device makes use of existing and widely used inclinometer measurement technology. The change of earth pressure in the sliding layer leads to changes in the shape and dimensions of the incinometer pipe. Careful measurements of these changes make it possible to backcalculate the pressure increment from the solution of a boundary value problem with properly described constitutive behaviors of the pipe and surrounding soil. An advantage of the inclinodeformometer is that it does not require any additional infrastructure than standard inclinometer pipes, even long after they are sheared and became unsuitable for inclinometer measurements. Full scale laboratory tests performed in a 2 m high calibration chamber demonstrated that simple constitutive models can be used for backcalculation as a first approximation. Initial field measurements performed on the St. Moritz landslide confirmed the existence of a compression zone in this constrained creeping landslide, and gave an order of magnitude for the pressure increment. This confirms the shear strength on the sliding surface decreased over time, implying that Brattas landslide in St. Moritz has to be analyzed considering a “potential failure scenario”.