scholarly journals Hydro-mechanical behaviour of a sandy silt from a river embankment

2020 ◽  
Vol 195 ◽  
pp. 01033
Author(s):  
Vincenzo Butticè ◽  
Alessio Ferrari ◽  
Carmine G. Gragnano ◽  
Guido Gottardi
Keyword(s):  
Mechanical Behaviour ◽  
Measurement Techniques ◽  
Degree Of Saturation ◽  
Confining Stress ◽  
River Level ◽  
Suction Control ◽  
Sandy Silt ◽  
Axial Translation ◽  
Safety Margins ◽  
River Embankment

The paper presents the results of an experimental campaign aimed at characterizing the hydro-mechanical behaviour of a sandy silt from a river embankment. Due to continuous river level fluctuations and changing climatic and environmental conditions, flood embankment materials experience frequent variations in degree of saturation and suction values. Such variations strongly impact the earthwork performance both in terms of seepage and stability conditions. For these reasons, a detailed characterization of the material behaviour in unsaturated conditions was carried out. Experiments were designed in order to highlight the response of the involved soil in terms of changes in matric suction and confining stress. All tests were performed on undisturbed samples from the embankment. To cover the suction range, which is expected to be significant for the material and assessed through field monitoring, a combination of several suction-control and suction-measurement techniques was used (e.g. negative water column, axial translation, tensiometers). Obtained results enabled (i) to quantify the evolution of the yield stress with suction, (ii) to assess the collapse upon wetting behaviour, (iii) to get detailed information on the water retention behaviour and (iv) to define the relative permeability of the soil. This extensive characterization work serves as a basis for the analysis of the embankment response following river level variations, the final purpose of the research being to establish a reliable methodology and a feasible procedure for the realistic assessment of the safety margins under transient seepage.

scholarly journals Hydro-mechanical behaviour of sandy silt under generalised stress conditions

2016 ◽  
Vol 9 ◽  
pp. 14014
Author(s):  
Enrique Romero ◽  
Octavio E. Cárdenas ◽  
Antonio Lloret ◽  
Rodrigo C. Weber
Keyword(s):  
Mechanical Behaviour ◽  
Stress Conditions ◽  
Sandy Silt

scholarly journals Effect of Geotextile Reinforcement on Shear Strength of Sandy Soil: Laboratory Study

2016 ◽  
Vol 38 (4) ◽  
pp. 3-13 ◽  
Author(s):  
Sidali Denine ◽  
Noureddine Della ◽  
Muhammed Rawaz Dlawar ◽  
Feia Sadok ◽  
Jean Canou ◽  
...  
Keyword(s):  
Shear Strength ◽  
Mechanical Behaviour ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Loose Sand ◽  
Test Results ◽  
Compression Tests ◽  
Confining Stress ◽  
Natural Sand ◽  
Confining Pressures

Abstract This paper presents results of a series of undrained monotonic compression tests on loose sand reinforced with geotextile mainly to study the effect of confining stress on the mechanical behaviour of geotextile reinforced sand. The triaxial tests were performed on reconstituted specimens of dry natural sand prepared at loose relative density (Dr = 30%) with and without geotextile layers and consolidated to three levels of confining pressures 50, 100 and 200 kPa, where different numbers and different arrangements of reinforcement layers were placed at different heights of the specimens (0, 1 and 2 layers). The behaviour of test specimens was presented and discussed. Test results showed that geotextile inclusion improves the mechanical behaviour of sand, a significant increase in the shear strength and cohesion value is obtained by adding up layers of reinforcement. Also, the results indicate that the strength ratio is more pronounced for samples which were subjected to low value of confining pressure. The obtained results reveal that high value of confining pressure can restrict the sand shear dilatancy and the more effect of reinforcement efficiently.

Impact of the Degree of Saturation on the Mechanical Behaviour of the Whitby Mudstone

2019 ◽  
Author(s):  
L. Douma ◽  
J. Dautriat ◽  
J. Sarout ◽  
D. Dewhurst ◽  
A. Barnhoorn
Keyword(s):  
Mechanical Behaviour ◽  
Degree Of Saturation

scholarly journals Numerical study of the application of capillary barrier systems for prevention of rainfall-induced slope instabilities

2020 ◽  
Vol 195 ◽  
pp. 01027
Author(s):  
Riccardo Scarfone ◽  
Simon J. Wheeler ◽  
Colin C. Smith
Keyword(s):  
Numerical Study ◽  
Slope Instability ◽  
Degree Of Saturation ◽  
Atmospheric Conditions ◽  
Capillary Barrier ◽  
Fine Grained ◽  
Suction Control ◽  
Fine Grained Soil ◽  
Improved Stability ◽  
Slope Instabilities

Slope instability is often caused by decreases in suction due to heavy and prolonged rainfall. In this study, the application of capillary barrier systems (CBSs) for suction control and slope stabilization purposes (i.e. reducing the risk of rainfall-induced slope instabilities) is analysed, due to their capacity to limit the percolation of water into the underlying soil. The behaviour of two slopes was studied numerically: a bare slope made of fine-grained soil and the same slope covered by a capillary barrier system. The time evolution of suction in the slopes subjected to realistic atmospheric conditions was studied by performing numerical finite element analyses with Code_Bright. In particular, multi-phase multi-physics thermo-hydraulic analyses were performed, modelling the soil-atmosphere interaction over periods of many years. Suction and degree of saturation distributions obtained from these analyses were then exported to the software LimitState GEO, which was used to perform limit analysis to assess the stability of the slopes. The CBS was able to limit the percolation of water into the slope and was shown to be effective in increasing the minimum values of suction attained in the underlying ground, resulting in improved stability of the slope.

Maximum Utilisation of Parts Process: A Method for Increased Precision of Component Lifetime Estimations in Medium Size Gas Turbines

2007 ◽  
Author(s):  
Pontus Slottner ◽  
Mathias Wa¨rja ◽  
Mattias Broddega˚rd
Keyword(s):  
Gas Turbines ◽  
Measurement Techniques ◽  
Failure Detection ◽  
Time Frame ◽  
Test Methods ◽  
Spare Parts ◽  
Medium Size ◽  
Process Data ◽  
Damage Models ◽  
Safety Margins

The goal of a maintenance strategy should be to reach a Retirement For Cause, RFC, condition, where components are not replaced until a potential failure has been detected. Further, the inspection interval should be large enough to allow spare parts to be ordered and delivered during the time between failure detection and failure, with sufficient safety margins. This requires measurement techniques that can monitor how the turbine is operated, prognostics capabilities that foresee maintenance needs, and test methods that can determine the state of a component during maintenance events. In general there are two ways to determine the amount of damage a gas turbine component has been subjected to — calculations and examination of service exposed components. Optimum results should be obtained by using calculations as a basis and continuously review/modify their interpretation and the underlying damage models using best available experiences. This paper describes the Maximum Utilisation of Parts Process, MUPP — a process for systematic testing of used components, how process data can be turned into modifications to a gas turbines maintenance schedule with same or decreased risks, and the implications for equipment operator as well as maintenance provider. It is concluded that MUPP allows significantly lower maintenance costs in the medium to long time frame.

Sign in / Sign up

Export Citation Format

Share Document