Construction and use of an inexpensive, lightweight free-fall penetrometer: applications to paleolimnological research

Abstract

This paper describes the construction of an inexpensive, lightweight, free-fall lake sediment penetrometer with application to paleolimnological research. This penetrometer is suitable for use in a variety of fresh water lake settings. Data are collected on a laptop PC, Palm OS handheld, or a Texas Instruments handheld data collection unit and are analysed using commercially available software. The quality of these data are adequate for determining changes in substrate type based on hardness. The unit can also be used to locate sites for optimum penetration of gravity cores and to calibrate sonar records. Addition of up to three optional transducers could expand the capabilities of the unit. Other potential uses include the determination of specific geotechnical properties of the lake sediment including the undrained shear strength.

Sediment identification using free fall penetrometer acceleration-time histories

“…Acceleration-time histories obtained from the impact of projectiles in geological materials have been used to evaluate the nature of the targeted material in areas like the study of planetary bodies (Garry et al 1999;Ko ¨mle et al 2001;Glaser et al 2008) and study of freshwater sediment in paleo-limnological research (Spooner et al 2004).…”

“…The variation of sediment type and layering characteristics have been studied using peak acceleration, penetration depth, and total embedment time (e.g., Spooner et al 2004;Stoll et al 2007;Stark and Wever 2009). The results of these studies have often produced quantitative data narrowly applicable to specific probe geometries or for a particular survey site.…”

An inexpensive and lightweight dynamic cone penetrometer for the characterization of shallow submerged sediments

“…These measurements can be made in the laboratory, but this requires very careful transfer of the samples (Hansbo, 1957; Nguyen & Mohajerani, 2012). Direct measurements in the field can be performed using static cone penetrometers (Bruzual & Millán Boadas, 2016; Medeiros et al, 2010; Tieppo et al, 2011), dynamic cone penetrometers (Herrick & Jones, 2002; Siekmeier et al, 2009; Vanags et al, 2004), free‐fall penetrometers (Abelev et al, 2009; Spooner et al, 2004; Stark et al, 2009) or even applied to submersibles vehicles (Stark et al, 2013). However, with few exceptions, in the intertidal environment (Hsu et al, 2009; Kelaher et al, 2003), most of the work in benthic biology or ecology measures these variables indirectly (Diaz et al, 1994; Meadows & Tait, 1989) probably because devices such as vane testers are not suitable for the infralittoral environment and other types of testers are expensive, sophisticated, unwieldy and/or aimed at subsurface studies for civil engineering and geotechnical studies.…”

Free-Falling Penetrometers: A Laboratory Investigation in Clay

“…Free falling penetrometers (FFP) are expendable or retrievable probes that are most commonly launched from small vessels and free-fall into the seabed. FFPs have been developed for many military and civilian applications, which include deep sea radioactive waste disposal carrier feasibility studies (Freeman et al 1984), naval mine countermeasure research (Lott and Poeckert 1996), seabed characterization (Dayal 1974), deepwater anchoring systems (Lieng et al 1999) and paleo-limonology applications (Spooner et al 2004). The application of FFPs in seabed characterisation is especially attractive, considering their relatively simple test equipment and procedure, which enables rapid testing with wider test area coverage than conventional full-flow or cone penetrometer tests.…”