SHALLOW MOVEMENTS IN CLAY RICH ROCKS DETECTED DURING SUBNORMAL PRECIPITATION PERIOD

摘要

The paper aims at the evaluation of the landslide movement monitoring near Trebenice town in the Ceske stredohori hilly land, Czechia. The monitored period between May of 2017 and January 2019 is characterized by negative effective precipitations and continually decreasing ground water levels in conditions of Cretaceous sedimentary rocks of different permeability. In the spring of 2017, the SAA (ShapeAccelArray) sensor was installed into the borehole placed one the most active part of the landslide area. Sensor was stabilized in 16 m depth, 2.5 m under the deepest sliding plane. SAA sensor automatically registers absolute values of displacements in different layers. The results indicate a slow movement above the shallower (4 m deep) sliding plane, with velocities changing significantly based on annual period from 3 mm/month during spring to 0 mm during late summer and autumn months. Measured displacements were confronted with course of GWLs, temperature and potential effective precipitation, to discover causes of the reversible movement.