Experimental and Numerical Investigations of a River Embankment Model under Transient Seepage Conditions

Ventini, Roberta; Dodaro, Elena; Gragnano, Carmine Gerardo; Giretti, Daniela; Pirone, Marianna

doi:10.3390/geosciences11050192

Cited by 7 publications

(12 citation statements)

References 28 publications

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“…Regarding the embankment body, all the tensiometers recorded an initial suction of approximately 5 kPa (Fig. 6), confirming the value of suction experimentally measured on the mixture after compaction and reported in [10].…”

Section: Resultssupporting

confidence: 87%

“…The river embankment model was prepared by using a mixture [10][11] composed of 70% by dry weight of Ticino sand (TS4 - [12][13]), and 30% of Pontida clayey sandy silt (PON - [10,[14][15]). The grain size distributions of the testing soils are shown in Fig.…”

Section: Centrifuge Test 21 Materialsmentioning

confidence: 99%

“…Soils used for the construction of river embankments are usually compacted to obtain adequate shear strength properties and to reduce the permeability, so the embankment model was compacted in four layers to the optimum Proctor Standard water content and dry density. The hydro-mechanical properties of the mixture are discussed in [10][11]. Mechanical and physical parameters assigned to the embankment body and foundation units according to advanced soil constitutive models are reported in [16].…”

Section: Centrifuge Test 21 Materialsmentioning

confidence: 99%

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Analysis of transient seepage through a river embankment by means of centrifuge modelling

et al. 2023

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Earthen river embankments are typically in unsaturated conditions during their lifetime and the degree of saturation within their bodies may vary significantly throughout the year, due to seasonalfluctuations of the river stage, as well as infiltrations of meteoric precipitation and evapotranspiration phenomena. Given the significant effects of partial saturation on the hydro-mechanical behaviour of soils, realistic assumptions on the actual water content distribution inside the embankments are essential forproperly modelling their response to hydraulic loadings. In this framework, centrifuge modelling is a useful tool to get insights into the evolution of saturation conditions of a water retaining structure during flood events. It allows for the direct observation of the groundwater flow process, which is hardly detectable at the prototype scale, enabling, at the same time, the validation and calibration of predictive numerical tools.In this paper, the results of a centrifuge test carried out on small-scale physical model of a compacted silty clayey sand embankment subjected to a simulated high-water event, at the enhanced gravity of 50-g, are presented and discussed. The physical model was carefully instrumented with potentiometers, miniaturized pore pressure transducers and tensiometers. Pore pressures and suctions measured during the experiment showed that the stationary flow conditions were reached only after an unrealistic hydrometric peak persistence. It therefore emerges that, for the design and/or the assessment of the safety conditions of a river embankment similar to the one tested, the simplified hypothesis of a steady-state seepage, in equilibrium with the maximum river stage expected could result, in many cases, an excessively conservative assumption.

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Section: Resultssupporting

confidence: 87%

Section: Centrifuge Test 21 Materialsmentioning

confidence: 99%

Section: Centrifuge Test 21 Materialsmentioning

confidence: 99%

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Analysis of transient seepage through a river embankment by means of centrifuge modelling

et al. 2023

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“…2.1 Equipment, tested material and test procedure A scheme of models tested is presented in Figure 1. The testing soils are Ticino sand (TS, Baldi et al, 1982, 1986, Fioravante, 2000, Jamiolkowski et al, 2003, Fioravante & Giretti, 2016 and Pontida clay (PON, Ventini et al 2021). TS is a coarse to medium, uniform silica sand, of alluvial origin, mainly com posed by angular grains; PON is a low plasticity kaoli nitic clayey silt, deposited in a post-glacial lake environment.…”

Section: Experimental Campaignmentioning

confidence: 99%

CPT calibration in centrifuge: Effect of partial saturation on cone resistance

Fioravante¹,

Giretti²,

Dodaro³

et al. 2022

Cone Penetration Testing 2022

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When dealing with unsaturated soil conditions, the influence of matric suction on cone tip resistance of the soil above the ground water table is typically neglected in engineering practice, with conse quent possible misinterpretation of soil features. In the last decades, various researchers have investigated the influence of suction on cone resistance for sands, whilst still little is known for silty materials, whose contri bution can be significant and extended for many meters above the groundwater table. Such issue is especially relevant for compacted earth structures, like river embankments, typically made of a heterogeneous mixture of intermediate soils. With the aim of providing a contribution and stimulating its correct implementation into geotechnical practice, a set of miniature piezocone tests have been carried out in a centrifuge on both saturated and partially saturated silty sand models. The interpretation of CPT results is discussed, highlighting the effect of partial saturation on cone tip resistance.

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“…Therefore, experimental determination of the effects of compaction on the hydromechanical behaviour of soils is essential for a reliable assessment of the stability of earthworks, to provide guidance in defining compaction specifications and, finally, as an aid in predicting the probability and type of collapse that may affect such structures. A methodological approach for the investigation of the hydromechanical response of river embankment, based on laboratory testing and numerical modelling was proposed by [7]. The Authors [7] proved the key role played by the characterization of a compacted mixture of sand and finer material under partially saturated conditions to analyse properly the performance of a typical embankment of the main river Po tributaries (Italy) under transient seepage.…”

Section: Introductionmentioning

confidence: 99%

Soil water retention curves of a silty clayey sand compacted at different dry density

2023

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The study of the hydraulic behaviour of compacted soils in partially saturated conditions is essential for understanding the engineering performance of geotechnical structures such as river embankments. The paper presents the results of an experimental study focusing on the effects of the initial water content and dry density on soil water retention curve (SWRC) and volume change of a compacted soil mixture under hydraulic loading. For this purpose, soil specimens compacted at different water contents(dry, wet and optimum water content), chosen on the basis of standard Proctor compaction test, were used. Specimens of a mixture composed of 70% Ticino sand (TS) and 30% Pontida silt (PON) have been tested. This is a heterogeneous mixture of sand and silt, that usually constitute the embankments of tributaries of river Po (Italy). The SWRCs along drying paths were performed by means of evaporation tests starting from the saturated conditions gained in permeameter tests. For the investigation of the change in the void index during the evaporation test, the volume variation of the tested specimens was estimated by means of a calliper and photographic comparison. Changes in the SWRCs are consistent with changes in specimen initial condition while the soil volume change exhibited at the end of evaporation test is always negligible.

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Experimental and Numerical Investigations of a River Embankment Model under Transient Seepage Conditions

Cited by 7 publications

References 28 publications

Analysis of transient seepage through a river embankment by means of centrifuge modelling

Analysis of transient seepage through a river embankment by means of centrifuge modelling

CPT calibration in centrifuge: Effect of partial saturation on cone resistance

Soil water retention curves of a silty clayey sand compacted at different dry density

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