Some observations on statnamic pile testing

Limited guidance on usage and methodology is currently available to engineers for the most common rapid load pile test, known as Statnamic. In order to improve the analysis of Statnamic testing in clay soils a full-scale instrumented auger bored pile was installed and tested in glacial lodgement till. As a result, improvements have been suggested in the test methodology and analysis. The inclusion of an accelerometer at the pile head would allow direct measurement of acceleration and verification of displacement measurements and velocity calculations. High-precision optical levelling of the pile before and after test cycles would allow multiple loading cycles to be considered cumulatively with greater confidence. The separation of the laser reference source from the test pile should be sufficient to avoid surface wave disturbance.Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.http://www.icevirtuallibrary.com/content/journal

Effects of planting density on tree growth and induced soil suction

Plant evapotranspiration (ET) is recognised to affect the soil suction of slopes and landfill covers. Previous work has focused on ET-induced suction by a single plant, with little attention paid to the effects of planting density. This study aims to quantify any changes in tree growth and tree-induced suction during ET and rainfall under different planting densities. A tree species, Schefflera heptaphylla, which is commonly found in Asia, was planted in silty sand at spacings of 60, 120 and 180 mm representing three different planting densities. For each case, three replicates were tested to consider any effects of tree variability. In total, the responses of suction for 297 seedlings subjected to drying and a rainfall event with a 10-year return period were measured. The test results show that reducing the tree spacing from 180 to 60 mm induced greater tree-tree competition for water, as indicated by a 364% increase in peak suction upon ET. Such tree-tree interaction led to (i) a 19-35% reduction in the leaf area index; (ii) a 17-36% decrease in root length; and (iii) an obvious decay of roots. Upon the rainfall event, the infiltration rate for vegetated soil with trees planted at a spacing of 60 mm was up to 247% higher than those for soil with a wider tree spacing, where mainly fresh roots were found. Although most suction within the root zone (i.e., top 100 mm) was lost due to increased infiltration at 60 mm spacing, suctions in deeper depths below root zone were largely preserved

Evaporite sinkholes of the Friuli Venezia Giulia region (NE Italy)

Sinkholes are common in the Friuli Venezia Giulia (FVG) Region (NE Italy), where the presence of karstifiable rocks favours their occurrence accelerated by intense rainfalls. Their existence has been reported since the end of the 1800s along the Tagliamento Valley, in correspondence with the mantled evaporites (gypsum). Furthermore, tens of evaporite sinkholes have been documented on the reliefs adjacent to the village of Sauris and along the narrow W\u2013Eoriented valleys, where regional faults have played a major role in their spatial distribution. This paper reports for the first time an inventory of the sinkholes affecting the evaporites of the FVG Region. These phenomena were mapped and categorised using a genetic classification. The main output is an A0-format map, which incorporates a 1:50,000 scale Sinkhole Inventory Map (SIM). The SIM encompasses 552 sinkholes. The cover suffosion sinkholes are the most abundant, followed by bedrock collapses. There is a clear prevalence of the circular shape (65%) over other shapes. Diameters are 1\u2013140 m, with depths ranging 0.1\u201340 m with a mean value of 4.5 m. The SIM can motivate regional planning authorities to perform further investigations aimed to understand the geomorphological evolutions of these phenomena

Unsaturated hydraulic properties of vegetated soil under single and mixed planting conditions

Effects of plant roots on changes of soil hydraulic properties, including soil water retention curves (SWRC) and soil hydraulic conductivity functions (SHCF), are not well understood, especially when soil is unsaturated and vegetated with multiple plant species. The aim of this note is to quantify the root effects on both SWRC and SHCF of silty sand using the instantaneous profile method. Four types of vegetated soil, namely bare, grass-only, tree-only and mixed tree-grass silty sand, were subjected to a controlled drying-wetting cycle in a plant room. Plant roots affect the air-entry value, saturated hydraulic conductivity and reduction rate of unsaturated hydraulic conductivity (with respect to suction) most significantly, but the roots do not affect the reduction rate of volumetric water content much. When planted with single species (grass or tree), the air-entry value of silty sand increased, while the saturated hydraulic conductivity and reduction rate of unsaturated hydraulic conductivity with suction decreased. However, under the mixed planting conditions, opposite results are found.</p

Geophysical monitoring of simulated clandestine graves using electrical and ground-penetrating radar methods: 0-3 years after burial.

This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated "wrapped" and "naked" burials were created. Multigeophysical surveys were collected over a 3-year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground-penetrating radar (GPR), and grave and background "soil-water" conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low-resistivity anomalies, whereas the wrapped burial had small, varying high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed the wrapped burial could be detected throughout, with the "naked" burial mostly resolved. Two hundred and twenty-five megahertz frequency GPR data were optimal. "Soil-water" analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target "wrapping" is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay-rich soils