Effect of rod friction on vane shear tests in very soft organic harbour mud

Very soft organic harbour mud is increasingly used as a filling and construction material in harbour construction and reorganization. The undrained shear strength of such soft sediments is the critical geotechnical soil parameter with regard to any specific construction design. Field and laboratory vane shear testing is a standard method to quickly determine this important parameter. So far, the effect of rod friction on vane shear tests in very soft organic soils is unclear. In this study we present results from laboratory experiments on harbour mud from a construction site in northern Germany. Relations among vane and rod geometry, penetration depth, water content, rod friction and undrained shear strength are derived. Based on these relations the influence of rod friction on vane shear test results is investigated. The results indicate that field and laboratory vane shear test measurements may be significantly influenced by rod friction. Methods are proposed to correct for the rod influence, which is shown to increase with rising water contents.     

Simulated effect of a forest road on near‐surface hydrologic response: redux

In the work reported here the comprehensive physics‐based Integrated Hydrology Model (InHM) was employed to conduct both three‐ and two‐dimensional (3D and 2D) hydrologic‐response simulations for the small upland catchment known as C3 (located within the H. J. Andrews Experimental Forest in Oregon). Results from the 3D simulations for the steep unchannelled C3 (i) identify subsurface stormflow as the dominant hydrologic‐response mechanism and (ii) show the effect of the down‐gradient forest road on both the surface and subsurface flow systems. Comparison of the 3D results with the 2D results clearly illustrates the importance of convergent subsurface flow (e.g. greater pore‐water pressures in the hollow of the catchment for the 3D scenario). A simple infinite‐slope model, driven by subsurface pore‐water pressures generated from the 3D and 2D hydrologic‐response simulations, was employed to estimate slope stability along the long‐profile of the C3 hollow axis. As expected, the likelihood of slope failure is underestimated for the lower pore pressures from the 2D hydrologic‐response simulation compared, in a relative sense, to the higher pore pressures from the 3D hydrologic response simulation. The effort reported herein provides a firm quantitative foundation for generalizing the effects that forest roads can have on near‐surface hydrologic response and slope stability at the catchment scale. Copyright © 2006 John Wiley & Sons, Ltd.     

Sandstone response to salt weathering following simulated fire damage: a comparison of the effects of furnace heating and fire

Fire has long been recognized as an agent of rock weathering. Our understanding of the impact of fire on stone comes either from early anecdotal evidence, or from more recent laboratory simulation studies, using furnaces to simulate the effects of fire. This paper suggests that knowledge derived from simulated heating experiments is based on the pre‐conceptions of the experiment designer – when using a furnace to simulate fire, the operator decides on the maximum temperature and the duration of the experiment. These are key factors in determining the response of the stone to fire, and if these are removed from real‐world observations then knowledge based on these simulations must be questioned. To explore the differences between heating sandstone in a furnace and a real fire, sample blocks of Peakmoor Sandstone were subjected to different stress histories in combination (lime rendering and removal, furnace heating or fire, frost and salt weathering). Block response to furnace heating and fire is discussed, with emphasis placed on the non‐uniformity of the fire and of block response to fire in contrast to the uniform response to surface heating in a furnace. Subsequent response to salt weathering (by a 10% solution of sodium chloride and magnesium sulphate) was then monitored by weight loss. Blocks that had experienced fire showed a more unpredictable response to salt weathering than those that had undergone furnace heating – spalling of corners and rapid catastrophic weight loss were evidenced in blocks that had been subjected to fire, after periods of relative quiescence. An important physical side‐effect of the fire was soot accumulation, which created a waxy, relatively impermeable layer on some blocks. This layer repelled water and hindered salt ingress, but eventually detached when salt, able to enter the substrate through more permeable areas, concentrated and crystallized behind it, resulting in rapid weight loss and accelerated decay. Copyright © 2007 John Wiley & Sons, Ltd.     

The impact of the hexos programme

In HEXOS, a programme of coordinated laboratory, field and model studies, an international group of participants has extended the range of measurements of evaporation from the sea and has investigated the role of droplets in the transfer of water to the atmosphere. Predictions of a rapid rise in the evaporation coefficient at wind speeds above 15 m s^-1 have not been substantiated. Wind stress measurements showed a relationship with wave age. New methods were developed for coping with flow distortion.     

Simulations of precipitation and atmospheric circulation changes associated with warm SSTs: results from an ensemble of long term integrations with idealized anomalies

A general circulation model is used to simulate the atmospheric response to a prescribed, idealized time varying warm sea surface temperature anomaly (SSTA) in the equatorial Pacific characteristic of ENSO events. The model incorporates the full seasonal cycle and an ensemble of five anomaly simulations, each of 14 months duration, is performed and the results compared with those from a ten year control simulation involving climatological SSTs. In a test of the model, simulated perturbations to precipitation patterns are compared with the analysis by Ropelewski and Halpert which identifies regions where precipitation perturbations are associated with the ENSO cycle. Strong and statistically significant perturbations are simulated throughout much of the equatorial Pacific and the Australian region which agree with the analysis. Perturbations over the Americas and the Indian sub-continent show part agreement with observations, while elsewhere, at more remote and high latitude locations, there is less agreement, providing some indication of model limitations in simulating the hydrological cycle. Over the equatorial Pacific most of the anomalous precipitation is accounted for by moisture flux convergence. Only in the vicinity of the maximum anomaly, located in the eastern Pacific, do warmer SSTs contribute to the perturbed circulation. Elsewhere, anomalous wind speeds mainly determine anomalous heat fluxes. As a result, the large scale perturbations to wind, moisture and precipitation appear to be forced indirectly, rather than directly as assumed in simple ocean-atmosphere models.     

The impact of the friction of distance on the early settlement and development of Eyre Peninsula,South Australia

The cost of overcoming distance has played and continues to play an important role in the evolution of Australia's space‐economy. This paper examines the impact of the ‘friction of distance’, as well as the quality of the resource base, on the settlement and development of Eyre Peninsula in South Australia. A series of maps portraying the spread of pastoralism and then agriculture on Eyre Peninsula reveals clearly the importance of ‘accessibility’ in influencing the pattern and timing of settlement. It was not until well into this century that all the potentially agricultural land in the interior was occupied, for this required the construction of a railway and water pipeline up the centre of the peninsula.     

The British isles and the age of exploration — a maritime perspective

The basic patterns of economic and political development of the British Isles region in a European context is outlined for the half century following Columbus’ discovery of America, noting the separate identities of England, Wales, Scotland and Ireland. The maritime dimension of these developments was based on trade with Europe, developed mainly in England and Scotland; and upon considerable development of the fisheries. Exploration and colonial expansion did not begin until after 1550 and continued into the seventeenth century. The historical role of the British Isles in Europe is considered as a sequence of approximately half-century phases extending from 1500 until the present, in which British maritime supremacy played a role in the nineteenth century similar to that played by the Spanish Empire in the sixteenth century.     

Potassium loss during metasomatic alteration of mica pyroxenite from Oldoinyo Lengai,northern Tanzania: contrasts with fenitization

Mica pyroxenite xenoliths, occurring as the cores of nephelinite and ijolite bombs in the pyroclastic deposits of the active volcano Oldoinyo Lengai, have undergone metasomatism in which K was lost and Fe²⁺ and Ti gained. This is unlike the alkali and ferric iron addition that typifies most examples of metastomatism adjacent to peralkaline igneous rocks in carbonatite complexes.