Liquefaction Assessment Using the CPT and Accounting for Soil Ageing

Due to its continuous data recording capability, excellent repeatability and accuracy, relatively low cost and simplicity of operation, the cone penetration test (CPT) offers enhanced liquefaction assessment over its predecessor the standard penetration test (SPT). However, soil ageing, which influences the cyclic resistance ratio (CRR), is difficult, if not impossible, to be detected by the CPT due to disturbance during the test. This situation may lead to excessively conservative estimation of CRR values which result in conservative assessment of liquefaction potential. This paper presents and discusses liquefaction assessment using the CPT and methods for accounting for soil ageing. A field study, conducted at Gillman, South Australia, is presented and the study site is assessed for liquefaction potential. This paper also explores the influence of soil ageing on the subsequent liquefaction assessment

Passive noise datasets at regolith sites

The data presented in this article contain datasets of passive noise measurements at regolith sites in Adelaide, South Australia. The data were acquired using three component (3C) LE-3Dlite Lennartz seismometers with an eigenfrequency of 1 Hz. The data were acquired at eight sites across Adelaide׳s regolith in a hexagonal array layout. Four tests, each with a duration of 30 min, were conducted at different times. The ambient noise data can be used for both horizontal to vertical spectral ratio (HVSR) analysis and array analyses, which are essential to obtain the site fundamental frequency and the ellipticity of the fundamental mode Rayleigh waves at the measured site. The array analyses are useful to obtain the dispersion curves, which are needed to estimate the shear wave velocity profile.Bambang Setiawan, Mark Jaksa, Michael Griffith, David Lov

A Pre-Landing Assessment of Regolith Properties at the InSight Landing Site

This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be ≥3--5 m thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.Additional co-authors: Nick Teanby and Sharon Keda

Quantifying the influence of rolling dynamic compaction

B.T. Scott & M.B. Jaksahttp://www.nzgeotechsoc.org.nz/anz-ygp-conference.cf

Mining applications and case studies of rolling dynamic compaction

B. T. Scott and M. B. Jaksahttp://anz2012.com.au

Evaluating rolling dynamic compaction of fill using CPT

Rolling Dynamic Compaction (RDC) is a ground improvement technique that involves compacting soil using a non-circular roller. Whilst conventional circular rollers are able to compact layer thicknesses typically in the range of 200 mm to 500 mm, thicker layers are able to be compacted using RDC. However, the depth of influence of RDC can vary significantly depending on the soil type, moisture content, loose layer thickness and number of passes. This paper focuses on how cone penetration testing was used during a compaction trial as a key site investigation technique to determine the zone of influence of RDC at a site involving quartzose and carbonate sand fill. The results presented quantify the increase in cone tip resistance with depth and illustrates how a number cone penetration tests (CPTs) were used to evaluate changes in soil strength due to increased roller passes, changes in moisture content or placed loose layer thickness.B.T. Scott & M.B. Jaks

Ground energy and impact of rolling dynamic compaction - results from research test site

As a major component of research activities at Sydney and Adelaide Universities into various aspects of rolling dynamic compaction as performed with the “square” impact roller, an experimental test site has been established. The test site is approximately 100m by 50m, and is part of a larger industrial property in Wingfield, South Australia. Geologically, the site comprises approximately 1-2m of non-engineered fill, overlying Estuarine deposits. The primary objectives of the work at the test site relate to quantifying the effects of the impact roller in terms of energy delivered to the ground and the ground response. Impact rollers with solid 4-sided modules of mass 8t and 12t are utilised. A monitoring and testing regime has been developed that includes physical measurements of energy on and below the impact module, surface settlement and sub-surface layer compression measurements. Early results from the testing programme provide a basis for understanding and developing the relationship of delivered to transmitted energy for the particular impact modules used at this site, the dissipation of energy through the ground and the effects on the various strata at depth due to module mass and number of passes (or energy input). The output from this study will form the basis for modelling ground conditions at this site and the effects of the impact rolling. The data thus generated will support further studies into numerical modelling of rolling dynamic compaction and the on-going programme of testing at other sites with different geological characteristics.D.L. Avalle, B.T. Scott, M.B. Jaks