1,721,007 research outputs found
Discrete piles for infrastructure slope stabilisation: instrumentation of piles at Hildenborough
No full textExpected impacts of climate change on vegetation and the stability of engineered clay slopes in the UK
No full textEffective-stress analysis of berm-supported retaining walls
No full textEarth berms left in place against a wall during bulk excavation can provide an effective means of enhancing the stability and reducing the displacement of an embedded wall. Stability calculations for an earth berm supported wall will often need to be carried out using effective stress (rather than total stress) analysis representing long-term or drained (rather than short-term or undrained) conditions. In this paper, a multiple Coulomb wedge analysis using effective stress soil parameters is used to estimate the pressure distribution on the wall as the result of the presence of the berm. Its use in limit equilibrium wall stability calculations is compared with two commonly used empirical methods of representing a berm in such an analysis. It is shown that the raised effective formation method of representing a berm—which gives good results in an undrained or total stress analysis—is unconservative for an analysis using effective stress soil parameters, and a modified raised effective formation method is proposed.<br/
Implications of climate change on infrastructure slopes
No full textThe clay soil-vegetation-climate model described in the Geotechnique paper by Smethurst Clarke and Powrie (2006) was used to simulate soil moisture deficits in clays soils at four sites in the UK. Historical climate data were used to calculate extreme soil moisture deficits and runoff from clay slopes. The relative frequency of extreme wet and dry years was calculated. Future climate change impacts were modelled using the UKCIP BETWIXT data sets and the relative frequency of extreme events was calculated for the 21st century and compared with the historical dat
Buildings on clay - the effects of geology, climate and vegetation on heave and settlement
No full text
Effects of climate change on cycles of wetting and drying in engineered clay slopes in England
No full textIn volume-sensitive clays the annual cycle of wetting and drying causes shrink and swell displacements. These movements cause damage to many infrastructure types, including railway and highway embankments and cut slopes, earth dams and flood embankments. At present there is little information on the impacts of expected climate change on the stability and serviceability of infrastructure embankments and slopes constructed of clay in the UK. In this paper, a water balance model is used to calculate daily changes in soil moisture content in the surface layers of a clay slope. Summer soil moisture deficit and winter runoff are calculated over a baseline period (1960–1991) for four locations in the UK. The calculations are repeated using synthetically generated time series of weather data representative of UKCIP climate change scenarios for the 21st century. Results indicate that recent summers considered to be exceptionally dry are likely to become the average condition later in the 21st century. Although total annual runoff is predicted to decrease, extreme wet events are still likely to occur. This will increase the magnitude of the cycles of winter soil wetting and summer drying. The implications for the design and maintenance of clay slopes and embankments are discussed
The influence of tree root water uptake on the long term hydrology of a clay fill railway embankment
No full textThis paper uses a numerical model to investigate the influence of tree root water uptake and tree removal on pore water pressures and the vertical movement of a clay fill railway embankment. Simulated results of soil wetting and drying are compared with field measurements from an instrumented railway embankment before and after tree removal. A parametric study compares the influence of vegetation on the seasonal movement of the embankment slope. The simulations and field measurements show that while trees cause significant seasonal variations in pore water pressure and water content near the soil surface, they can maintain persistent soil suctions at depth within the tree rooting zone. Demonstration of this result using a numerical model requires a root water uptake function that separates spatially the processes of water infiltration, evaporation and transpiration. When all of the trees are removed, the persistent soil suctions established by the trees are lost as water infiltrates from the soil surface. Leaving the trees in place over the bottom third of the slope can maintain persistent suctions at the slope toe, while potentially also reducing seasonal ground movements at the crest that may adversely affect railway track geometry
Centrifuge modelling of a cutting slope stabilised by discrete piles
No full textA series of four centrifuge model tests was carried out to investigate the effectiveness of a single line of discrete piles in stabilising a cutting slope in uniform clay. Various numerical techniques were used to back-analyses the results of the model tests. In this report, the testing procedure is described and the results are presented and discussed with reference to finite element analyses and previously published work. <br/
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