La memoria descrive tre casi di frane a cinematica estremamente lenta (velocità di spostamento media inferiore a 10 mm/anno) ubicate nella valle glaciale alpina dell’Isarco, tra Bolzano e Bressanone. Le tre frane sono riattivazioni parziali di DGPV, sviluppatesi dopo l’ultima glaciazione in rocce vulcaniche o metamorfiche e si classificano come scorrimenti rotazionali profondi di roccia e detrito. Si descrivono i sistemi di monitoraggio di spostamenti e pressioni interstiziali, attivi da un minimo di 5 anni ad un massimo di 20, che sono stati installati per la definizione dei meccanismi di evoluzione dei movimenti. Si evidenziano i metodi di elaborazione delle misure, finalizzati al controllo dell’affidabilità delle stesse, e si riportano le interpretazioni dei meccanismi di frana effettuate mediante verifiche di stabilità a ritroso.
Major transport infrastructures connecting Italy to central Europe (such as state roads, motorway E45, national railway and the planned high-speed railway TEN-T5) run through the alpine Isarco Valley. Slopes of the Isarco valley are affected by deep seated rock slides and gravitational slope deformations, which are quite common features in previously glaciated valleys. The paper describes three case studies of such type of slope movements (herein referred to as V70, T64 and V58), that are characterized by extremely slow movement rates and that interact some of the above mentioned infrastructures. Displacements and pore water pressures of the landslides have been monitored for a minimum of 4 years to a maximum of 16 years. Redundant displacement measures were collected by using Total Station, inclinometers and in-place inclinometers, and revealed that in all the sites the displacement rate is lower than 10 mm/year. Except for site V70, where rates seem to be independent from the small water table oscillation, slight accelerations were observed when the Isarco river increased its discharge level during rainfall periods. Back-analysis revealed that mobilized residual shear strength is higher than it is when evaluated by laboratory tests, and that pore-water pressure distribution has a significant influence on slope stability only for sites V58 and V64.
FRANE A CINEMATICA ESTREMAMENTE LENTA IN UNA VALLE GLACIALE DEL CORRIDOIO TEN-T5
SIMEONI, Lucia;
2014-01-01
Abstract
Major transport infrastructures connecting Italy to central Europe (such as state roads, motorway E45, national railway and the planned high-speed railway TEN-T5) run through the alpine Isarco Valley. Slopes of the Isarco valley are affected by deep seated rock slides and gravitational slope deformations, which are quite common features in previously glaciated valleys. The paper describes three case studies of such type of slope movements (herein referred to as V70, T64 and V58), that are characterized by extremely slow movement rates and that interact some of the above mentioned infrastructures. Displacements and pore water pressures of the landslides have been monitored for a minimum of 4 years to a maximum of 16 years. Redundant displacement measures were collected by using Total Station, inclinometers and in-place inclinometers, and revealed that in all the sites the displacement rate is lower than 10 mm/year. Except for site V70, where rates seem to be independent from the small water table oscillation, slight accelerations were observed when the Isarco river increased its discharge level during rainfall periods. Back-analysis revealed that mobilized residual shear strength is higher than it is when evaluated by laboratory tests, and that pore-water pressure distribution has a significant influence on slope stability only for sites V58 and V64.Pubblicazioni consigliate
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