Soft Peaty Research Articles

Long Term Behaviour of An Asphalt Pavement Structure Constructed on a Geogrid-Reinforced Subgrade Over Soft Soils

Many roads with asphalt pavement are being reconstructed every year, as their quality becomes insufficient by the requirements. As it is well- known, old roads were built not in the very best quality, so doing reconstruction projects in the most cases there were required to deal with soft soils that are under the existing road structure. Geogrid reinforcement was widely used to solve issues of soft soil in Lithuania. There are projects where geogrid reinforcement is used to control road pavement roughness when there are layers of peat or silt under road structure instead of using concrete piles or geosynthetic-encased soil columns. This type of geogrid reinforcement application is unexplained in any normative-technical document but widely used in Lithuania. This application was usually made constructively without any calculations, choosing the reinforced solution by reducing the geogrid tensile strength or layer quantity compared to reinforced load transfer platform over piles. This paper evaluates the long-term influence of geogrid- reinforced subgrade on the roughness of asphalt surfacing and bearing capacity of the road structure when the soft peaty soils stratify in the deeper layers of the subgrade. There were compared the reinforced sections to adjacent sections to see the effect and fortunately a large number of adjacent sections were also strengthened, mostly by lime stabilisation. Therefore, this comparison allows making more insights on the long-term performance of the strengthened subgrade and influence on the road quality. This research gives recommendations on how the geogrids has to be selected to be used in this kind of application.

Larval burrow morphology and groundwater dependence in a mire-dwelling dragonfly,Petalura gigantea(Odonata: Petaluridae)

Most species of petalurid dragonflies have a fossorial larval stage, which is unique in the Odonata. Larvae typically excavate burrows in soft peaty soils in mires, seepages or along stream margins, which are occupied by a single larva throughout the long larval stage. This paper reports on a study of burrow morphology in Petalura gigantea, with the objectives of describing their burrows, documenting any variability in burrow morphology across the hydrogeomorphic range of habitats used by the species, identifying factors contributing to any such variability, resolving questions in relation to the single previous illustration of a burrow system and identifying the level of groundwater dependence of larvae. The species was found to be an obligate, groundwater dependent, mire-dwelling species with well-maintained and sometimes complex burrows. Burrow complexity and morphological variation are inferred to be a response by larvae to the hydrogeomorphic characteristics of the habitat and substrate attributes. A...

Field Performance of PVD Combined with Reinforced Embankment on Peaty Ground

This paper describes the field performance of prefabricated vertical drains (PVD) used in combination with reinforced embankments on peaty ground. A large-scale field test of PVD adopted in combination with an embankment reinforced using galvanized steel grid was conducted on peaty ground in Hokkaido, Japan. Although the site was characterized by extremely soft peaty ground, a stable, high embankment 11.8 m in thickness was successfully constructed through the combination method. A consolidation-accelerating improvement from the PVD and a reinforcement effect from the steel grid were clearly observed, and settlement of the PVD-improved peat layer corresponded roughly with Barron's solution with consideration to well resistance. However, it was necessary to make the coefficient of consolidation nine times as large as that seen in the results of oedometer testing. The surcharge embankment allowed a reduction of the coefficient of secondary consolidation for the overconsolidated peat layer (overconsolidation ratio: approx. 1.13) to approximately 60% that of the normal consolidated layer.

Deep dry mix ground improvement of a soft peaty clay using blast furnace slag and red gypsum

The paper describes a field trial using deep in situ dry soil mixing to stabilize soft peat deposits beneath the route for the Channel Tunnel Rail Link in the SE of the UK. The aim of this trial was to evaluate whether a ground granulated blast furnace slag (GGBFS)–red gypsum mixture could be used as a replacement for a cement-based binder. Red gypsum is produced as a co-product to the production of the white pigment titanium dioxide. Trial columns were installed adjacent to the main stabilization works. A combination of in situ and laboratory testing has shown that the blended binder was as effective as ordinary Portland cement in increasing the strength of the peat. The blended binder columns also displayed similar durability characteristics. Using the alternative binder required no alteration to existing equipment and caused no reduction in production rates. The minerals formed in the samples from the GGBFS–red gypsum columns were of the type formed by pozzolanic reactions and the strength of the GGBFS–red gypsum columns was dependent on achieving a pH of 10.5. The paper recommends that peat samples must be stored in airtight containers prior to initial design mix testing. If required, the pH of the soil–binder mixes should be adjusted (using a small addition of lime) during the treatment process.

Experimental Study on Irrigation Pipelines embedded in Stabilized Soft Peaty Ground

Experimental Study on Irrigation Pipelines embedded in Stabilized Soft Peaty Ground

Settlement and Deformation of Irrigation Pipelines laid on/embedded in Soft Peaty Ground

Settlement and Deformation of Irrigation Pipelines laid on/embedded in Soft Peaty Ground

Site investigations for unretained excavations in a soft peaty deposit : Sandroni, S S; Silva, J M J; Pinheiro, J C N Can Geotech JV21, N1, Feb 1984, P36–59

Site investigations for unretained excavations in a soft peaty deposit : Sandroni, S S; Silva, J M J; Pinheiro, J C N Can Geotech JV21, N1, Feb 1984, P36–59

Site investigations for unretained excavations in a soft peaty deposit

As part of an urbanization scheme, artificial islands are being created on the swampy land around the Itaipu lagoon, close to Rio de Janeiro. The islands are being formed by hydraulic filling with sand and their periphery consists of retaining walls resting on sand cushions. The very soft local soils pose settlement and stability problems in execution and operation.A site and laboratory investigation program, involving several types of triaxial, consolidation, and in-situ vane tests, has been carried out and is described. A full-scale instrumented settlement fill has been built and is mentioned. An instrumented 5 m deep trial trench has been carried out and monitored during the excavation stage which took 5 days and during a 45 day long repose stage. In both these stages failure was avoided by keeping water inside the trench at its original level. Finally, failure was induced by pumping water out of the trench. The observations at the trial trench are presented and discussed in some detail. Keywords: soft organic deposit, unretained excavation, field tests, laboratory tests, displacements, pore pressures, failure.

An Outbreak of Plumbism in Horses, Due to the Solvent Action af a Soft Peaty Water on Lead Piping

An Outbreak of Plumbism in Horses, Due to the Solvent Action af a Soft Peaty Water on Lead Piping

An Outbreak of Plumbism in Horses, Due to the Solvent Action of a Soft Peaty Water on Lead Piping

An Outbreak of Plumbism in Horses, Due to the Solvent Action of a Soft Peaty Water on Lead Piping