River embankment characterization: The mutual utilization of geophysical and geotechnical techniques

Abstract

Latest ton events in Northern Italy (especially in the Veneto part) bring brought lake embankments in to the focus of community attention. A majority of these embankments tend to be more than a century old and possess come continually restored, to make sure that detailed information to their current framework is usually missing. The monitoring of these frameworks is now based, in most cases, on visual assessment and localized measurements of embankment material variables. However, this monitoring is normally inadequate to be certain an adequate security amount against flooding. Hence there was an ever-increasing interest in smooth and accurate study methods, particularly geophysical method. These skills can provide detailed information regarding subsurface structures, become non-invasive, affordable, and more quickly than old-fashioned techniques. However, needed confirmation to offer reliable information, particularly in intricate and reworked man-made frameworks such as for example embankments. Contained in this report we existing a case study whereby three different geophysical practices have already been applied: electric resistivity tomography (ERT), regularity site electromagnetic induction (FDEM) and soil Penetrating Radar (GPR). Two test web sites have already been selected, both found in the Province of Venice (NE Italy) the spot where the Tagliamento River enjoys large embankments. The outcome gotten with these strategies being calibrated against evidence solving from geotechnical investigations. The pros and drawbacks of every techniques, as well as their relative merit at identifying the particular options that come with the embankments in this region, include highlighted. The outcomes describe that geophysical method can supply really valuable details for embankment characterization, so long as the information explanation try constrained via drive proof, albeit limited in space.

Introduction

The dramatic flood events that took place North-Eastern Italy, and especially how to delete eris account in the Veneto part, in highlighted the extreme susceptability that characterizes the local river embankments, plus the pressing importance of a process enabling an improved control of these tissues. A proper characterization of levees in addition to their basis layers is actually, as a whole, one of the main equipment for flooding threat minimization. This issues is due to the exemplary alterations in the water amounts that heed intense precipitation activities might cause the collapse with the levee program. The elements of embankment failure, which entail both streamside and the landside mountains (plus the basis level), become from the change in the hydraulic program of lake movement. As an example, high-water level a€“ prolonged in time a€“ may gradually trigger saturation of containment buildings, reducing their opposition. However, a rapid decreasing associated with the water level, such as those happening inside origin step of an overflow, may cause the development of hazardous purification causes to the streamside.

The heterogeneity in the whole grain hydraulic characteristics for the dirt producing the embankment and its foundation can lead to the synthesis of preferential seepage paths and/or the removal of dirt particles eventually resulting in weaken (inner erosion). Erosion can also happen in discontinuities along rigid frameworks inserted within the levee. Burrows excavated by pets particularly beavers and nutrias may also be harmful causes for inner erosion.

In practice, the procedures defined above aren’t easily detectable, because they develop with no superficial proof before collapse for the levee system. As embankment spying try, in reality, at this time based on aesthetic assessment and localized specifications (example. utilizing piezometers) regarding the land details, it is scarcely shocking your regular spying are insufficient to make certain an adequate safety level. This is why precisely why the demand for smooth and comprehensive, while nonetheless useful, researching means is quickly growing. Geophysical practices is a feasible choice, because they’re responsive to soils/rocks actual land and factors which, therefore, tend to be connected with grain dimensions, porosity, drinking water content material, and temperatures (Reynolds, 2011). These land properties and county factors can hence create information on subsurface faculties and may getting specially useful in finding subsurface top features of geotechnical and engineering interest. Plus, these methods can cover large parts from the investigated system, usually with meter solution, in fairly short period of time.