It is essential to understand the geotechnical properties of the ground before anything can be built on Earth, the Moon, or elsewhere. The cone penetrometer is a simple but very important instrument that yields quantitative and qualitative information about the geotechnical properties of the material. Quantitative information is the penetration resistance from which density and layering can be inferred, and ground improvement can be evaluated. Qualitative information includes identifying layering and inhomogeneities, as well as the existence of boulders.Cone penetrometers are often proposed for space missions (e.g., Beagle 2, InSight, Philae) and were even used by Apollo astronauts. All cone penetrometers that have been used extra-terrestrially so far have either experienced difficulties with penetration or were designed to penetrate less than 100 mm deep and stop before encountering any meaningful resistance. An optimally developed dynamic cone penetrometer might work better because it requires less reaction force.This research consists of the development of a bespoke dynamic cone penetrometer with variable cone size and hammering energy. Further, this instrument is tested in a large-scale regolith compaction chamber with lunar highlands regolith simulant LHS-1E at a wide range of densities to find the optimal setup where penetration captures enough data by moving slowly but also does not stagnate. Results from dynamic cone penetration tests at many different densities are compared and successfully correlated to cone penetration and nuclear density gauge test results. Calculated coefficients allow for the conversion directly between dynamic and regular cone penetration tests at any density, which shows promise for greater use of dynamic cone penetrometers in lunar applications.

Abstract National Aeronautics and Space Administration (NASA) is preparing to deploy astronauts for detailed exploration of the lunar South Pole, an area primarily composed of lunar highlands regolith. A comprehensive understanding of the composition, properties, and behavior of this surface material is critical to the success of the mission, to advancing the field of lunar exploration research, and future endeavors on the Moon. This study showcases the findings from laboratory tests conducted using a scaled-down model of two types of compaction equipment: a vibrating smooth drum roller (VSDR) and a rolling dynamic compaction (RDC) 4-sided impact roller. The experiments were performed using 1:13 scale models and utilized lunar highland simulant as the test material. Surface settlements, earth pressure cells, and densities were measured to quantify the extent of improvement for these two different compaction techniques. The results indicate that the vibrating smooth drum roller technique outperforms the impact roller in surface settlement, density, earth pressure and acceleration, demonstrating superior performance in compacting lunar highland regolith simulant.

NASA is soon to send astronauts to explore the Moon near the lunar South Pole, which is predominantly composed of lunar highlands regolith. Understanding the lunar ground is an essential aspect of this endeavor. This study presents the results of laboratory testing involving a 1:13 scale model of a vibrating drum roller compactor incorporating a lunar highland simulant. Surface settlements, earth pressures, and densities were measured to quantify the extent of improvement. The results demonstrate that the technique is effective in compacting the near-surface regolith simulant. Further studies are required to determine the most effective travel speed and frequency of vibration.

Vibratory and impact rollers achieve deeper lift compaction than static rollers. Ground improvement with impact rollers occurs through rolling dynamic compaction, enabling compaction to significant depths, generally more than 1m. This provides the opportunity to place thick layers, potentially with a larger maximum particle size than conventional smooth drum rollers, while achieving engineering standards of density and stiffness. The overall consequence of this is that the earthworks exercise becomes a far more sustainable activity. Deeper lift compaction beyond traditional thin compacted layers using conventional heavy vibratory rollers has been achievable for some time, but to lesser depths than is possible with impact rollers. The compaction of deeper lifts at faster operating speeds, albeit, typically with a greater number of passes, requires a fresh look at specifications for infrastructure earthworks. The paper explores the green credentials of deep lift compaction, by comparing earthworks plant, productivity and fuel usage for compaction using conventional circular drum rollers with thin layers, and deeper lift compaction using vibratory and polygonal impact rollers. Quality control to greater depths can be a limiting factor. Testing protocols often require modification to accommodate the changes in layer thicknesses and material specifications.

Rolling dynamic compaction (RDC) is a specific type of dynamic compaction, which involves towing a heavy non-circular module at a relatively constant speed. This paper investigates the effects of module mass, operating speed and varying ground conditions on the effectiveness of the 4-sided impact roller using a developed finite element method (FEM)-discrete element method (DEM) model. Numerical results were analysed from four aspects, namely the energy imparted to the ground, soil velocity vectors, module imprint lengths and soil displacements at different depths. It is found that, a heavier module mass induces greater ground improvement in terms of both energy delivered to the soil per impact and the magnitude of soil displacements. The energy imparted to the underlying soil by the module increases with greater operating speed. The rotational dynamics of the module also change with increasing operating speed, whereby the impacts are delivered by the faces of the module at typical operating speeds; however, at faster speeds the impacts are delivered towards the corners of the module and the behaviour is less reproducible. The modelling showed that soil with a higher initial Young’s modulus and a higher internal angle of friction decreases the magnitude of soil displacements, which confirms that the impact roller is less able to significantly improve soils that are stiff or have a high initial shear strength.

Rolling dynamic compaction (RDC) is a soil improvement technique, which involves towing heavy (6-15 t), non -circular (3-, 4-, and 5-sided) modules behind a tractor to achieve soil compaction. Both potential and kinetic energies are imparted to the underlying soil as the modules fall and impact the ground. This paper presents a combined, three-dimensional finite element method (FEM)-discrete element method (DEM) model to investigate the behaviour of the 1:13 scale, 3-sided roller. Numerical results are compared against results from a field study using the corresponding full-size, 3-sided roller in two aspects namely, ground settlements and induced peak pressures. It is demonstrated that the numerical results are in very good agreement with the field observations. This paper examines the influence of the twin modules of the 3-sided roller with respect to ground improvement and the results suggest that the soil beneath a single module is improved solely by the module above it. Therefore, the current practice of using the total weight of the 3-sided roller to predict the energy imparted to the ground and the depth of influence should be avoided. The validated numerical model is also used to predict the energy delivered to the soil and the depth of influence of the roller. The energy imparted to the ground is approximately 22.5 +/- 3 kJ per impact with 95% confidence, and the depth of influence is approximately 1.5 m for each of the twin modules of the 13-t, 3-sided roller operating at 11 km/h on granular soils investigated in this study.

Four fine-grained soils from South Australia containing differing particle size distributions were tested for their soil water retention properties. Despite their wide-ranging index properties, the samples from all four sites were confirmed to contain fractal particle size distributions (PSD) from sieve and hydrometer testing. Air entry values were obtained for each site from soil water retention curves (SWRC) that were generated using an unsaturated triaxial device with a pore air pressure/volume controller and a high air entry porous disk, which confirmed all sites contained fractal pore size distributions. The fractal dimensions of the particle and pore size distributions were not equal for any of the four sites tested in this paper. Using the four sites described in this paper, comparisons are presented between experimental SWRC results, theoretical results underpinned by fractal theory, and predictions derived from a curve fitting equation based solely on PSD and soil index properties. Lastly, this paper discusses the importance of understanding the unsaturated behaviour of fine-grained soils and some of the challenges associated with aligning current industry practice and advances in research within the field of unsaturated soil mechanics.

The depth of influence of rolling dynamic compaction (RDC) was investigated in a field trial using a four-sided impact roller. Earth pressure cells (EPCs) were placed at varying depths at a site consisting of homogeneous soil conditions. EPCs measured pressures imparted by RDC at 3·85 m depth; however, the largest magnitudes of pressure were confined to the top 2 m beneath the ground surface. These results were complemented by field density data, penetrometer and geophysical testing. A number of published case studies using the 8 t four-sided impact roller, for either improving ground in situ or compacting soil in thick layers, are summarised in this paper. Finally, equations are presented that predict first, the effective depth of improvement, appropriate for determining the depth to which the ground can be significantly improved in situ, and, second, the depth of major improvement for RDC, appropriate for thick-layer compaction.

Rolling dynamic compaction (RDC) is a ground improvement technique, which involves towing a non-circular module behind a tractor to achieve soil compaction. When compared against conventional static and vibratory compaction techniques, RDC is capable of compacting thicker layers of soil and at a faster operating speed. This study validates the developed numerical scale model against a field study using the full-size RDC module. Numerical results were compared with the field data in four aspects namely, displacements at the ground surface, and at depths of 0.7 and 1.1 m, pressures at 0.7 and 1.1 m depths, energy delivered by the RDC module into the underlying soil, and the depth of improvement. It is concluded that, numerical results are in good agreement with the field data. This paper also proposes that pressure results are an imperfect indicator to assess the optimum number of RDC passes, whereas, ground settlement is recommended since it better reflects ground improvement due to RDC and it has a clear relationship with the number of passes.

Rolling dynamic compaction (RDC) is a ground improvement method that involves towing, typically with the aid of a tractor, a 3-, 4or 5-sided, non-circular module. Due to the mechanics of its operation, as well as the increased travel speed of 10–12 km/h when compared with the 4 km/h speed of conventional vibrating and drum rollers, RDC has demonstrated improved earthworks efficiency and greater effectiveness at depth below the ground surface. Despite the significant benefits derived from RDC, much research is needed to facilitate the development of models to predict the extent of ground improvement, as a function of soil type, ground conditions, travel speed, module type and weight, and the number of passes. This paper presents the results of an extensive research program undertaken to quantify the behaviour of RDC and its consequent effect of the ground. The research involves field studies incorporating in situ measurement, laboratory testing of small-scale physical models involving novel instrumentation, numerical modelling using dynamic finite element analyses, and the implementation of artificial intelligence. Each of these aspects is treated in detail in the paper.

The influence of towing speed on the effectiveness of the 4-sided impact roller using earth pressure cells（EPCs） is investigated.Two field trials were undertaken;the first trial used three EPCs placed at varying depths between 0.5 m and 1.5 m with towing speeds of 9-12 km/h.The second used three EPCs placed at a uniform depth of 0.8 m,with towing speeds of 5-15 km/h.The findings from the two trials confirmed that towing speed influences the pressure imparted to the ground and hence compactive effort.This paper proposes that the energy imparted to the ground is best described in terms of work done,which is the sum of the change in both potential and kinetic energies.Current practice of using either kinetic energy or gravitational potential energy should be avoided as neither can accurately quantify rolling dynamic compaction（RDC） when towing speed is varied.

Rolling dynamic compaction (RDC) is typically used for improving ground in situ or compacting fill in thick lifts. In many project applications, the effects of RDC are verified by way of testing that is undertaken pre- and/or post-compaction. This study presents results from a full-scale field trial that involved placing an earth pressure cell (EPC) and accelerometers at a depth of 0·7 m within a 1·5 m thick layer of homogeneous sandy gravel to measure the response to RDC in real-time. Double integration of acceleration–time data enabled settlement to be inferred, while the EPC measured the change in stress due to impact. The maximum change in vertical stress recorded over the 80 passes undertaken was approximately 1100 kPa. During a typical module impact, the loading and unloading response occurred over a duration of approximately 0·05 s. The acceleration response of RDC was measured in three orthogonal directions, with the vertical accelerations dominant.

A full scale trial pile wall was constructed as part of an initial investigation for a road underpass project in Adelaide, South Australia. The purpose of the trial was to determine if a soldier piled retaining wall could support a deep vertical excavation upon wetting up of the unsaturated clay behind the wall. Soils encountered in this case study were clays of low-to-medium plasticity, and were shown to be fractal via the use of sieve and hydrometer testing, whereby a linear relationship between particle size and percentage passing was obtained when plotted on a logarithmic scale. The confirmation of this Adelaide clay soil being fractal, and that fractal dimensions of particle size and pore size distributions are not equal, are findings that are of significance in gaining a greater understanding of unsaturated soil behaviour. Soil water characteristics inferred from fractal theory are described within this paper, in addition to the results obtained from laboratory testing for suction and moisture content of soil sampled during the trial investigation.

French title: Modelisation physique du compactage roulant dynamique Abstract in English and French

Rolling dynamic compaction (RDC) is a soil improvement technique that involves a heavy noncircular module (impact roller) that rotates about a corner as it is towed, causing the module to fall to the ground and compact it dynamically. While conventional circular rollers are able to compact layer thicknesses typically up to 500 mm, thicker layers are able to be compacted using RDC due to the dynamic effect of the module, which yields a greater depth of influence. When combined with the ability to compact ground efficiently, by means of its faster operating speed (9–12 km/h) when compared to conventional circular rollers, RDC can be a productive and cost-effective option in many different earthwork applications. However, the depth of influence of RDC can vary significantly depending on the soil type, moisture content, loose layer thickness, or number of passes adopted. Applications of RDC as well as verification techniques that can be used to quantify ground improvement are presented. A featured case study investigates the zone of influence of a 4-sided impact roller that was measured in a systematic fashion in the field by means of a number of earth pressure cells that were buried at varying depths beneath the ground surface and measuring the in situ stress over a range of module passes. In addition, a variety of in situ tests were performed including penetrometer, field density, and geophysical testing to measure density improvement, again as a function of the number of module passes. The field measurements conducted on mine tailings indicated that the depth of improvement due to RDC exceeded 2 m below the ground surface. At a depth of 1.5 m, RDC imparted soil stresses of approximately 150 kPa into the ground; positive pressure readings were also measured by earth pressure cells buried up to 3.85 m below the ground surface, indicating that the actual zone of influence (for which there is improvement) extends beyond this depth.

Rolling Dynamic Compaction (RDC) is a soil improvement technique, which involves a heavy (6– to 12–tonne) non-circular module (impact roller) that rotates about a corner as it is towed, causing the module to fall to the ground and compact it dynamically. This paper focuses on the 4-sided module and aims to quantify the effectiveness of RDC by means of a combination of field studies and numerical modeling. The field studies involved embedding earth pressure cells beneath the ground at varying depths and measuring the in situ stress over a range of module passes. In addition, a variety of in situ tests were performed including penetrometer, field density and geophysical testing to measure density improvement, again as a function of the number of module passes. The field measurements indicated that the depth of improvement exceeded 2 meters below the ground surface. Numerical modeling was undertaken using the dynamic finite element analysis software, LS-DYNA; the results align well with those obtained from the field studies. Parametric studies were also undertaken to determine the influence of varying soil parameters on the effectiveness of RDC. RÉSUMÉ: Le Compactage Dynamique Roulant (CDR) est une technique d'amélioration du sol, qui implique un lourd module de forme non circulaire (6 à 12tonnes), rouleau à impact, qui tourne autour d'un coin lorsqu’il est tiré, ce qui provoque la chute du module sur le sol et le compacte dynamique. Cet article se concentre sur le module à 4 faces et vise à quantifier l'efficacité du CDR par le biais d'une combinaison d'études sur le terrain et de modélisation numérique. Les études de terrain ont comporté l’installation de cellules de contraintes dans le sol à différentes profondeurs et à mesurer ainsi la contrainte lors des passages du module. En outre, de nombreux essais in situ ont été réalisés, comprenant des pénétromètres, des essais de densité en place et des tests géophysiques afin de mesurer l’amélioration de la densité en fonction du nombre de passes de modules. Les mesures sur le terrain ont indiqué que la profondeur de l'amélioration a dépassé les 2 mètres sous la surface du sol. La modélisation numérique a été réalisée en utilisant le logiciel d’analyse par éléments finis en dynamique, LS-DYNA ; les résultats concordent bien avec ceux obtenus dans les études sur le terrain. Des études paramétriques ont également été entreprises pour déterminer l'influence de divers paramètres du sol sur l'efficacité du CDR.

PreviousNext No AccessProceedings of the 9th SEGJ International Symposium, Sapporo, Japan, 12-14 October 20093D treatment of MASW data for monitoring ground improvement at uncontrolled fill sitesAuthors: Koya SutoBrendan ScottKoya SutoTerra Australis Geophysica Pty Ltd, [email protected],Search for more papers by this authorEmail the author at [email protected] and Brendan ScottURS Australia Pty Ltd, [email protected]Search for more papers by this authorEmail the author at [email protected]https://doi.org/10.1190/segj092009-001.52 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InReddit Abstract The output from a Multichannel Analysis of Surface Waves (MASW) survey is essentially a series of 1-dimensional S-wave velocity profiles, which are often expressed in 2-dimensional sections along each of the survey lines. Location of each 1-dimensional data point can be defined using X-Y coordinates, and an S-wave velocity profile with depth can be obtained at each data point. An MASW survey provides a dense coverage of analysis points, making it possible to obtain output over a survey area in a 3-dimensional data set. This paper shows two MASW surveys carried out at a football ground and an industrial development site in eastern Australia, where uncontrolled fill was encountered. In the first site, recent dry weather caused shrinkage of the fill causing sink holes, and the second site needed required competence for the building. The purpose of the MASW survey was to monitor the uniformity of the fill after ground improvement. As conventional geotechnical data are available at the second site, a comparison is tried with the MASW results. Here, the fill was subsequently further improved and compacted using a 4-sided impact roller. Results from the MASW survey were presented in 1-, 2-, and 3-dimensional formats. The MASW survey was used to distinguish between areas of site that were deemed satisfactory and other areas where further ground improvement was needed to facilitate future development at the sites. The high density sampling frequency of the MASW survey enabled loose fill layers at depth to be identified and quantified in 3-dimensional space, which lead to timely and cost-effective project outcomes. Permalink: https://doi.org/10.1190/segj092009-001.52FiguresReferencesRelatedDetailsCited byThe Dissents of the Berch CourtSSRN Electronic JournalMASW surveys in landfill sites in AustraliaKoya Suto6 June 2013 | The Leading Edge, Vol. 32, No. 6 Proceedings of the 9th SEGJ International Symposium, Sapporo, Japan, 12-14 October 2009 ISBN (print):978-4-938493-06-6ISSN (online):2159-6832 Copyright: 2009 Pages: publication data© 2009 Published in electronic format with permission by the Society of Exploration Geophysicists of JapanPublisher:Society of Exploration Geophysicists HistoryPublished Online: 29 Oct 2012 CITATION INFORMATION Koya Suto and Brendan Scott, (2009), "3D treatment of MASW data for monitoring ground improvement at uncontrolled fill sites," SEG Global Meeting Abstracts : 1-4. https://doi.org/10.1190/segj092009-001.52 Plain-Language Summary PDF DownloadLoading ...