Embankment dam seepage evaluation from resistivity monitoring data

Abstract

Methods for monitoring seepage are important for the safety of embankment dams. Increased seepage may be associated with internal erosion in the dam and internal erosion is one of the main reasons for dam failures. Internal erosion progresses inside the dam and is difficult to detect by conventional methods. Therefore there is a need for new or improved methods. The resistivity method is a nondestructive method that may accomplish this task. It has been tried in an on‐going research programme in Sweden. Daily resistivity measurements are carried out on permanent installations on two Swedish embankment dams. In this paper the installations on the Sädva embankment dam are described and selected parts of the results are presented. In addition, a method for evaluating the seepage from resistivity monitoring data is theoretically described and tested for four selected areas in the foundation of the Sädva dam. Seasonal resistivity variations are apparent in the reservoir as well as inside the dam. Most parts of the dam have a homogeneous resistivity distribution with consistent variations. The overall status of the dam is satisfactory. However part of the foundation demonstrates a slightly different behaviour pattern with regard to the seasonal variation. The four selected areas represent localities with low, intermediate and high variations in seasonal resistivity. The areas are compared qualitatively and thereby permeable zones within the dam may be identified. Quantitative assessment of the seepage flow is also carried out as an initial test of the described method. It is concluded that the experiences from the Sädva dam are valuable with regard to the use of the resistivity method on embankment dams. Resistivity monitoring data may be used to qualitatively assess the seepage through the dam. For quantitative assessment, the method is promising and the data from the Sädva dam constitute an interesting initial approach. However, many assumptions and simplifications are made and more work on refining the method is needed.

The VLF-EM imaging of potential collapse on the LUSI embankment

“…Embankment collapse may be caused by subsidence, liquid saturation, fracture or crack in the embankment, and others. Resistivity method (Al-Fares, 2011;Bedrosian et al, 2012;Chen et al, 2006;Dahlin and Johansson, 1995;Dahlin et al, 2008;Jackson et al, 2002;Jones et al, 2012;Karastathis et al, 2002;Oh, 2012;Panthulu et al, 2001;Sjödahl et al, 2002Sjödahl et al, , 2005Sjödahl et al, , 2008Sjödahl et al, , 2009, seismic method (Bedrosian et al, 2012;Chen et al, 2006;Deidda and Ranieri, 2005;Karastathis et al, 2002;Osazuwa and Chinedu, 2008;Zhu et al, 2011), ground penetrating radar (GPR) method (Di Prinzio et al, 2010;Golebiowski, 2010;Karastathis et al, 2002;Loperte et al, 2011) and self potential method (Bolève et al, (Sukardi, 1992), location of active and inactive gas bubble in December 2008, and two faults (Siring fault with NE-SW direction and Watukosek fault with NW-SE) identified based on the location of bubbles, gravity data , and the major trend of horizontal displacement (Istadi et al, 2012). (b) Profile lines survey in LUSI embankment observed in the 24th of April 2008 (for interpretation of the references to color in this figure legend, the reader is referred to the web version of the article).…”

4D electrical resistivity tomography monitoring of soil moisture dynamics in an operational railway embankment

“…; Oh ) and monitoring (Sjodahl et al . , , ). Relatively few examples exist for transportation earthworks.…”

“…; Sjödahl et al . , ; Niesner ; Wilkinson et al . ), although to the best of our knowledge this approach has not yet been applied to transportation earthworks.…”

Geophysical investigation for the rehabilitation of a flood control embankment

“…, ) and it is nowadays considered a well‐established tool for dam investigation, as confirmed by recent developments (Sjödahl et al . ; Bolève et al . ).…”

“…Surface and cross‐well electrical DC methods (Johansson and Dahlin ; Cho and Yeom ; Sjödahl et al . ) have been extensively used to map seepage‐induced resistivity changes, as well as preferential flow pathways associated with lowered resistivity values within the structure (Sjödahl et al . 2006, ).…”