River embankment characterization: The joint utilization of geophysical and geotechnical method

Abstract

Previous ton events in north Italy (particularly in the Veneto part) bring delivered lake embankments in to the focus of community interest. A number of these embankments tend to be more than 100 years older and have now become continually restored, to make certain that detailed information on the current build is generally lost. The tabs on these frameworks happens to be founded, by and large, on graphic review and localised dimensions for the embankment information details. But this tracking is usually insufficient to make sure a sufficient security stage against flooding. Hence there’s an ever-increasing interest in quick and precise investigation means, eg geophysical method. These skills can supply detailed information from the subsurface tissues, were non-invasive, affordable, and more quickly than traditional strategies. However, they want verification to be able to render trustworthy success, particularly in complex and reworked man-made tissues including embankments. Inside report we provide an incident learn whereby three different geophysical skills have been used: electric resistivity tomography (ERT), frequency website electromagnetic induction (FDEM) and floor Penetrating Radar (GPR). Two examination sites have-been picked, both found in the state of Venice (NE Italy) where Tagliamento lake has actually huge embankments. The outcome obtained by using these practices are calibrated against research solving from geotechnical investigations. The professionals and cons of each method, as well as their general quality at identifying the particular popular features of the embankments in this region, tend to be emphasized. The results express that geophysical method can provide really valuable details for embankment characterization, provided the info understanding was constrained via drive evidence, albeit set in area.

Introduction

The remarkable ton activities that occurred in North-Eastern Italy, and particularly in the Veneto Region, in highlighted the ultimate vulnerability that characterizes the regional river embankments, therefore the pressing need for a method permitting a far better control over these architecture. A suitable characterization of levees as well as their foundation layers try, in general, one of the primary resources for flooding chances mitigation. This threat is because of the excellent changes in the water amounts that adhere extreme precipitation happenings and will cause the failure of this levee program. The components of embankment collapse, which include both the streamside plus the landside slopes (and the foundation level), are from the change in the hydraulic regime of river circulation. Like, high water stages a€“ prolonged eventually a€“ may progressively cause saturation in the containment architecture, decreasing their own weight. Alternatively, an instant reducing regarding the water-level, like those happening during the origin state of an overflow, could cause the development of dangerous filtration power towards streamside.

The heterogeneity in the whole grain size and hydraulic residential properties in the earth producing the embankment and its own base can result in the formation of preferential seepage pathways and/or the removal of dirt particles in the end leading to weaken (inner erosion). Erosion can also happen in discontinuities along stiff buildings inserted when you look at the levee. Burrows excavated by pets including beavers and nutrias may unsafe triggers for interior erosion.

In practice, the steps described above are not effortlessly noticeable, as they progress without the shallow research till the collapse from the levee system. As embankment spying is actually, in fact, at this time according to visual review and localised measurements (e.g. making use of piezometers) regarding the land variables, its hardly surprising your regular tracking try inadequate to ensure an adequate security stage. Because of this the reason why the need for fast and considerable, while nevertheless helpful, researching means was fast increasing. Geophysical practices is a feasible selection, as they are responsive to soils/rocks actual qualities and variables which, consequently, are connected with whole grain proportions, porosity, drinking water content, and heat (Reynolds, 2011). These land qualities and county variables can ergo incorporate information on subsurface characteristics and certainly will getting specially beneficial in finding subsurface popular features of geotechnical and technology interest. Moreover, these processes can cover big parts of this investigated program, often with meter solution how much is Eharmony vs Christian mingle, in relatively short time.