Acoustic Emission Behavior and Monitoring of Soils

Abstract

As far as nondestructive testing methods are concerned, acoustic emission techniques are relatively recent additions to the rock monitoring area (dating from the late 1930's) and to the metal testing area (dating from the 1950's). Its application to soils is an even more recent event with little activity prior to the 1970's. However, over the past five to ten years, interest has been generated in the soils area to the point where at least five equipment manufacturers are currently marketing acoustic emission systems specifically for geotechnical engineering applications. This activity is seemingly well founded, for acoustic emissions are indeed generated by deforming soil masses and technical feasibility is now firmly established. This state-of-the-art paper on acoustic emission activity in soils presents these findings on the basis of fundamentals, small-scale laboratory tests, and large-scale laboratory tests. Furthermore, the technique has been applied to field situations in a number of cases. These include slope stability monitoring of dams and embankments, soil movements arising from horizontal and vertical deformations, seepage monitoring, and grout/hydrofracture monitoring. Specific case histories in each group are presented. Collectively taken, the information available seems encouraging enough for many investigators to use the technique for a wide variety of applications. With a multi-faceted attack, the current qualitative status of the technique (that is, no acoustic emission indicates stability; low acoustic emission indicates small movement; moderate acoustic emission indicates larger movement; high acoustic emission indicates instability) should move into a better defined quantitative status. In this latter case, acoustic emission signatures of different soils could lead to instant assessment of actual stress levels in any given situation.

Characterizing the complexity of seismic signals at slow-moving clay-rich debris slides: The Super-Sauze (Southeastern France) and Pechgraben (Upper Austria) case studies

“…This observation is consistent with 5 laboratory experiments (e.g. Koerner et al 1981). The normalized difference (%) between the maximum amplitude of the signal and the median value of all maximum amplitudes for the considered event also show drastic attenuation with distance (Fig.…”

Quantification of reactivated landslide behaviour using acoustic emission monitoring

“…The most significant contribution in the area of AE behaviour of soil has been made by Koerner et al (1981) who carried out extensive laboratory and field studies of both fundamental AE characteristics of soil and field applications. This work demonstrated that deforming soil produces detectable AE and that the levels of emissions are directly related to the stress state of the soil.…”

“…inter-particle friction). Koerner et al (1981) and Dixon et al (2003) found that AE generated by soil is influenced by particle size and shape, with larger more angular particles generating greater amplitude stress waves as a greater magnitude of work is required to overcome interlock. Other properties that influence the AE response of soil include; grading, moisture content and plasticity.…”

Monitoring buried pipe deformation using acoustic emission: quantification of attenuation

“…Koerner et al, 1981), and they form a significant percentage of buried pipelines. This study therefore focused on steel pipes.…”

“…Generated AE rates are proportional to applied displacement rates, where the coefficient of proportionality Smith et al Monitoring Buried Pipe Deformation Using AE: Quantification of Attenuation 17/08/2016 3 is dependent on the depth to the shear surface and the distance AE propagates along the waveguide to the ground surface where it is measured. Quantifying this magnitude of attenuation for each installation is essential to deriving slope displacement rates from measured AE rates, which can be used to warn users of accelerating slope deformation behaviour to enable evacuation of vulnerable people and timely repair and maintenance of critical infrastructure (Koerner et al, 1981;Nakajima et al, 1991;Smith et al, 2014a;Smith et al, 2014b;Dixon et al, 2015a;Dixon et al, 2015b;Smith, 2015;Smith & Dixon, 2015;Smith et al, 2016).[Insert Figure 1 here] Developments in AE monitoring of pipe networks (e.g. Alleyne & Cawley, 1992;Alleyne & Cawley, 1997) for the detection and location of defects (e.g.…”