An experimental method to study the drying-wetting behaviour of a sand

Milatz, Marius

doi:10.1201/b19248-32

Cited by 4 publications

(11 citation statements)

References 6 publications

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“…This sand is of sedimentary origin from the river Elbe at Hamburg and is used as backfilling material for quay wall construction. In different experiments the hydraulic and hydromechanical behaviour of this sand has been investigated (Milatz, 2013;Milatz and Grabe, 2014;Milatz and Grabe, 2015;Milatz, 2015). The same sand will be investigated in the studies presented in this contribution with the focus on hydro-mechanical coupling and settlements induced by changes in the hydraulic state.…”

Section: Experimental Investigation Of Settlement Behaviour 21 Invesmentioning

confidence: 99%

“…Selected soil parameters of CTB-sand are summarised in table 1. The main findings on the hydraulic behaviour of CTBsand are its low capillarity with a void ratio-dependent air entry value (AEV) of the soil-water characteristic curve of 2.5 to 3 kPa and a pronounced hysteretic behaviour with air entrapment on drying-wetting cycles (Milatz, 2015;Törzs, 2015).…”

Section: Experimental Investigation Of Settlement Behaviour 21 Invesmentioning

confidence: 99%

“…For this purpose a vacuum method for suction control was applied and a topcap tensiometer implemented to the simple shear apparatus. This method was enhanced to study the drying-wetting behaviour in cylindrical sand specimens under oedometric stress conditions for cyclic hydraulic paths in Milatz (2015) and Törzs (2015). In the executed hydraulic tests on sand specimens with a diameter of 50 mm and initial height of 20 mm a pore water volume change was prescribed with a computer-controlled enhanced precision pore water pressure controller (GDS Instruments).…”

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

“…The negative pore water pressure is then directly measured with the topcap tensiometer. Typical results of a hydraulic test with cyclic hydraulic loading using the topcap tensiometer with the flat ceramic disc from Milatz (2015) are represented in figure 3. It can be seen that the test results from conventional methods to obtain the soil-water characteristic curve are well reproduced.…”

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

“…On rewetting of the sand specimens significant air entrapment was discovered with an air degree of saturation S a = 1 -S r ≈ 0.18 reached after the first wetting path (Milatz, 2015). Therefore, the sand specimens are rewetted only up to Sr = 0.82 to avoid over-saturation.…”

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

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Settlements in unsaturated granular soils induced by changes in saturation and suction

2016

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In this contribution the hydro-mechanically coupled behaviour of a sand is experimentally investigated with the focus on settlements induced by changes in degree of saturation and suction. This phenomenon, referred to as collapse behaviour, is attributed to rearrangements of the grain skeleton due to changing capillary effects on wetting of the soil. For the experimental investigation of the collapse behaviour of a medium coarse sand cyclic dryingwetting tests are performed under oedometric conditions. In the test setup a sand specimen, subjected to a constant small vertical stress, is cyclically dried and wetted by volume control of the pore water, whereas matric suction is measured using a tensiometer implemented to the specimen loading plate (topcap tensiometer). The test procedure, originally designed to investigate the hysteretic nature of the soil-water characteristic curve of the sand, allows to measure the one dimensional volume change of the specimen as evoked by the applied hydraulic paths under constant net stress. By varying the specimen void ratio the impact of density on the collapse behaviour can be assessed. The test data is important for the development of a mechanical constitutive model which can take the volume change behaviour due to suction changes into account.

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Section: Experimental Investigation Of Settlement Behaviour 21 Invesmentioning

confidence: 99%

Section: Experimental Investigation Of Settlement Behaviour 21 Invesmentioning

confidence: 99%

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

Section: Test Set-up and Testing Proceduresmentioning

confidence: 99%

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Settlements in unsaturated granular soils induced by changes in saturation and suction

2016

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An automated testing device for continuous measurement of the hysteretic water retention curve of granular media

Milatz

2020

Acta Geotech.

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The water retention curve (WRC), representing an important key for the modelling of hydro-mechanical behaviour of unsaturated soils, is still not fully understood, because it originates from microscopic hydraulic and capillary phenomena. Furthermore, its experimental measurement, especially for cyclic drainage and imbibition paths, is challenging and timeconsuming. In this contribution, a recently developed low-cost easy-to-use miniature testing device for the investigation of the WRC of unsaturated granular soils, such as coarse-grained sand and a packing of glass beads, is presented. With the help of the new device, that can be controlled by a Raspberry Pi single-board computer, the hysteretic WRC can be investigated in a conventional macroscopic approach by plotting the macroscopic specimen degree of saturation versus measured matric suction. The test setup allows an automatic measurement of the WRC which is measured continuously following a programmed test procedure. In addition to the technical realisation of the new device, this contribution focuses on macroscopic results of water retention tests. Moreover, the testing device has been designed in a miniaturised size, in order to obtain microscopic insights into the phase distribution during cyclic drainage and imbibition paths with the help of computed tomography in future applications.

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Theoretical and experimental investigations on the role of transient effects in the water retention behaviour of unsaturated granular soils

Milatz

Törzs

Nikooee

et al. 2018

Geomechanics for Energy and the Environment

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An experimental method to study the drying-wetting behaviour of a sand

Cited by 4 publications

References 6 publications

Settlements in unsaturated granular soils induced by changes in saturation and suction

Settlements in unsaturated granular soils induced by changes in saturation and suction

An automated testing device for continuous measurement of the hysteretic water retention curve of granular media

Theoretical and experimental investigations on the role of transient effects in the water retention behaviour of unsaturated granular soils

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