bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual identification of1O2-induced crystal structure transformation of single Zr-MOF by dark-field microscopy
Authors: Xu Yue , Li Qian , He Wei , Yang Chang Ping , Gao Peng Fei , Li Yuan Fang , Huang Cheng Zhi
Published: April 2023

Understanding the structural transformation of photocatalysts under illumination provides detailed insights to solve the poisoning of photocatalysts.
Electrophilic and nucleophilic gas phase reactivity of the Janus cluster-based anions [{Mo6Cl8}Cl5□]− (□ = lacuna)
Authors: Denis Antoine , Tymínska Nina , Delhaye Thomas , Molard Yann , Gerbaux Pascal , De Winter Julien , Himdi Mohamed , Castel Xavier , Costuas Karine , Cordier Stéphane , Rondeau David
Published: April 2023

The Janus-reactivity character of the monoanion [{Mo6Cli8}Cla5□a]− that leads to an unprecedented self-reactivity is proved by CID-MS-MS and quantum chemical studies.
Embedding alloying sites in a lithiated polymer matrix as a stable interphase of lithium electrodes
Authors: Xiong Tengpeng , Li Zhendong , Yao Xiayin , Peng Zhe
Published: April 2023

A stable interphase of lithium electrodes is designed by embedding alloying sites in a lithiated polymer matrix, and endows the lithium growing behavior with high uniformity and stability.
Construction of Pd-based coordination cages with three geometrically distinct ligands
Authors: Li Ru-Jin , de Montmollin Jean , Fadaei-Tirani Farzaneh , Scopelliti Rosario , Severin Kay
Published: April 2023

The combination of three structurally distinct dipyridyl ligands with Pd2+results in the formation of a heteroleptic [Pd4L2L′2L′′4]8+cage, which could be characterized by single crystal X-ray crystallography.
Correction: Mesoporous polyvalent Ni–Mn–Co–O composite nanowire arrays towards integrated anodes boosting high-properties lithium storage
Authors: Zhou Junxiang , Wang Yudeng , Feng Bo , Sun Yong , Wang Jiafu
Published: April 2023

Correction for ‘Mesoporous polyvalent Ni–Mn–Co–O composite nanowire arrays towards integrated anodes boosting high-properties lithium storage’ by Junxiang Zhou et al., Dalton Trans., 2023, 52, 3526–3536, https://doi.org/10.1039/D3DT00211J.
Surface n-type band bending for stable inverted CsPbI3perovskite solar cells with over 20% efficiency
Authors: Wang Shuo , Li Ming-Hua , Zhang Yanyan , Jiang Yan , Xu Li , Wang Fuyi , Hu Jin-Song
Published: April 2023

Inverted CsPbI3perovskite solar cells offer merits for tandem and indoor photovoltaics.
Synthesis of β-iodovinyl sulfonesviadirect photoinitiated difunctionalization of internal alkynes
Authors: Abramov Vladimir A. , Topchiy Maxim A. , Rasskazova Maria A. , Drokin Egor A. , Sterligov Grigorii K. , Shurupova Olga V. , Malysheva Anna S. , Rzhevskiy Sergey A. , Beletskaya Irina P. , Asachenko Andrey F.
Published: April 2023

Direct iodosulfonylation of internal alkynes with sulfonyl iodides, photoinitiated by violet LED light, proceeds under mild conditions, transition metals and photocatalyst free. Reaction has good functional group tolerance and high product yields.
Self-assembly induced ferromagnetic interaction in magnetic polymers with terphenyl linkers
Authors: Ji Shengqi , Yuan Xiaoyan , Guo Qianjin , Ren Lixia
Published: April 2023

Self-assembly is a universal method to prepare block copolymers with ordered structures, which is very important in organic magnets to align the magnetic centres to enhance ferromagnetic interaction.
Temperature-responsive membrane permeability of recombinant fusion protein vesicles
Authors: Powers Jackson , Jang Yeongseon
Published: April 2023

In this study, we investigate the changes in the permeability of the recombinant fusion protein vesicles with different membrane structures as a function of solution temperature.
Backscatter‐assisted Non‐orthogonal multiple access network for next generation communication
Authors: Xie Ximing , Ding Zhiguo
Published: April 2023

Non‐orthogonal multiple access (NOMA) technique introduces spectrum cooperation among different users and devices, which improves spectrum efficiency significantly. Energy‐limited devices benefit from the backscatter (BAC) technique to transmit signals without extra energy consumption. The combination of NOMA and BAC provides a promising solution for Internet of Things (IoT) networks, where massive devices simultaneously transmit and receive signals. This study investigates a system model with two NOMA downlink users and an uplink device. The aim is to maximise the data rate of the uplink device by optimising the power allocation coefficient and the backscattering coefficient. Meanwhile the quality of service requirements of two NOMA users are guaranteed. The closed‐form solution of two optimisation variables is derived, and an alternating algorithm is also proposed to solve the formulated optimisation problem efficiently. The proposed system verifies the feasibility of IoT devices being added into existing networks and provides a promising solution for wireless communication networks in the future.
The positive history of an error. Modelling the heave of a nuclear power station
Authors: Alonso Eduardo
Published: April 2023

The paper describes two different procedures to explain and to model the observed heave of a nuclear power plant founded on an expansive unsaturated claystone. In the initial model developed, the claystone was represented by a double structure (micro-macro) expansive clay. Field swelling records were accurately reproduced and the model was used to predict the long-term (40 yr) expected vertical displacements. Years after, it was realized that a more consistent explanation for the observed heave was the precipitation of gypsum crystals in discontinuities. The alternative physical phenomenon led to a re-formulation of an appropriate model, which is described in the paper. The key aspect of the long-term heave was the presence of anhydrite in the claystone mineralogical composition. The paper explains the physics of crystal growth that was triggered by the construction of the power station, the large excavation performed to locate the plant buildings and by the presence of a phreatic level, that was a consequence of the geometry of excavations. The new model, substantially more complex than the first one, is also able to reproduce available laboratory long-term swelling tests and field observations. It is hopefully a more reliable model to predict the long-term behaviour. The positive part of this history is that the initial model inspired the development of successful elastoplastic constitutive models for expansive clays.
Effects of thermal cycles on soil behaviour: theoretical and experimental studies
Authors: Ng Charles W. W. , Zhou Chao , Zhang Shuai , Zhang Qi
Published: April 2023

Fundamental understanding and proper modelling of soil behaviour under thermal cycles are increasingly important and essential for the analysis and design of many emerging infrastructures, such as geothermal structures and embankment-atmosphere interactions under a changing climate. Previous studies mainly focus on monotonic thermal loading of thermo-mechanical behaviour of soils. Based on a unified, state-dependent theoretical framework in the form of compliance matrix, a new constitutive model is developed to simulate the cyclic thermo-mechanical behaviour of saturated and unsaturated soils. This new bounding surface model is formulated in terms of Bishop’s stress and suction. Apart from the loading and bounding surfaces, a memory surface is incorporated in the model to simulate cyclic thermal behaviour of soils. To verify the new model, computed results are compared with measured data from cyclic heating-cooling tests on saturated and unsaturated soils at various suctions. Based on this new model, two engineering applications are analysed including cyclic thermally loaded floating energy pile foundations and a deep excavation in the unsaturated ground. Consistent results are obtained between computed and measured data.
Effect of Hydro-Mechanical Hysteresis on Active Earth Pressure for Unsaturated Soils
Authors: Shwan Bestun
Published: April 2023

Stability analysis of retaining structures carried out at unsaturated conditions mainly dismissed the effect of hydraulic and mechanical hysteresis on the exerted active thrust. This paper reports a parametric study into the influence of hydraulic and mechanical hysteresis as well as soil types on active earth pressure carried out at low and high suction profiles to envision the pattern of the exerted active thrust for various simulated soils, from sands to clays. Generally, the numerical results exhibited a non-linear relationship between active thrust and suction. The influence of hydraulic and mechanical hysteresis and soil types on the active thrust was seen very significant. A reduction inPaof 1.62 fold ats= 137.34 kPa, owing to the influence of hydraulic and mechanical hysteresis, was obtained when comparing two simulated soils; silt and clay. A soil with a wider capillarity range showed a higher positive effect of the hydraulic and mechanical hysteresis on the exerted active thrust.
Modeling seismic compression of unsaturated soils in the funicular regime
Authors: McCartney John , Kinikles Dellena
Published: April 2023

A semi-empirical elasto-plastic constitutive model with a hyperbolic stress-strain curve was developed with the goal of predicting the seismic compression of unsaturated sands in the funicular regime of the soil-water retention curve (SWRC) during undrained cyclic shearing. Using a flow rule derived from energy considerations, the evolution in plastic volumetric strain (seismic compression) was predicted from the plastic shear strains of the hysteretic hyperbolic stress-strain curve. The plastic volumetric strains are used to predict the changes in degree of saturation from phase relationships and changes in pore air pressure from Boyle’s and Henry’s laws. The degree of saturation was used to estimate changes in matric suction from the transient scanning paths of the SWRC. Changes in small-strain shear modulus estimated from changes in mean effective stress computed from the constant total stress and changes in pore air pressure, degree of saturation and matric suction, in turn affect the hyperbolic stress-strain curve’s shape and the evolution in plastic volumetric strain. The developments of the new mechanistic model developed in this study will play a key role in the future development of a holistic model for predicting the seismic compression across all regimes of the SWRC.
Relating wave frequency and pore fluid homogeneity in quasi-saturated sands
Authors: Flood-Page Guillaume , Boutonnier Luc , Pereira Jean-Michel
Published: April 2023

P-wave velocity is regularly proposed as a proxy for water saturation when studying quasisaturated soils. However, several authors have underlined that this velocity can only be reliably correlated to water saturation if the pore fluid is “homogeneous”. Using bender elements to measure compression wave velocity in quasi-saturated Fontainebleau sand, we show it is highly sensitive to both saturation and frequency. The characteristic length of pore pressure diffusion is used to explain the link between frequency, gas distribution and P-wave velocity. This criterion is shown to be fairly reliable for assessing the homogeneity of a pore fluid distribution in quasi-saturated Fontainebleau sand.
Soil Moisture Active Passive (SMAP) Satellite Data and Unsaturated Soil Response
Authors: Farahani Ali , Ghayoomi Majid , Jacobs Jennifer M.
Published: April 2023

The importance of degree of soil saturation in geotechnical problems resulted in inclusion of unsaturated soil mechanics in various applications for several decades. However, in spite of recent progress in remotely sensed soil moisture measurement, geotechnical community has not yet taken advantage of these advances in analysis of unsaturated soils. NASA launched its Soil Moisture Active Passive (SMAP) satellite in 2015 with the aim of providing surface and root zone soil moisture content over the global land surface at 3-day average intervals. SMAP, as a widely validated and near-real-time database, offers a rich soil moisture database at a global scale that can be used in studies considering unsaturated soil behaviour. A study of the relationship between soil water content and seismic ground response is presented in this paper using SMAP, which includes the tracking of the variations in Earth's surface soil moisture caused by earthquakes.
One-dimensional cyclic loading tests on saturated and unsaturated sand-clay mixtures
Authors: Khoshghalb Arman , Li Jiacheng , Shahbodagh Babak
Published: April 2023

A series of one-dimensional cyclic loading tests are carried out on three different proportions of Sydney sand – kaolin mixtures, at various initial degrees of saturation. The settlement of the samples throughout the tests is accurately monitored. The effects of the degree of saturation and frequency of the cyclic load on the evolution of the settlement during the tests are thoroughly investigated for each mixture. The settlement patterns are compared to those of saturated samples to highlight the effect of soil suction on the behaviour. The results show that soil settlement decreases while the time required for the completion of the primary consolidation increases with the decrease in the degree of saturation of the soil. This trend is more pronounced in soils with higher kaolin content. The loading frequency, however, seems to have negligible effects on the settlement behaviour of unsaturated soils under cyclic loading. The result of the study provides valuable data for future simulations and validations of various constitutive models.
A simplified approach to estimating the evolution of residual shear strength of unsaturated soils with suction
Authors: Bardanis Michael , Grifiza Sofia , Feuillas Marianna
Published: April 2023

Several researchers have investigated the effect of suction and partial saturation on the angle of residual shear strength. Most of these investigations involve the adoption and application of a method of controlling suction on the ring shear apparatus and performing ring shear tests on the same soil for various values of suction. Methods adopted include both the axis translation technique for control of suction over the range 50-1500 kPa and the saturated salt solutions method for control of suction in the range of several MPa. The general picture from these investigations is that the residual shear strength failure envelope remains linear but corresponding to higher values of the angle of residual shearing resistance for constant suction; this value increasing with increasing suction. The paper presents an attempt to normalise values of measured angle of residual shearing resistance for various suction values with the angle of residual shear strength of the corresponding fully saturated soil. This normalisation verified the linear increase of the ratio tanφres(s)/tanφres(s=0)with suction. This linear increase allows for estimation of the evolution of tanφres(s)with suction if φres(s)for one specific suction can be measured. This observation led to the measurement of tanφres(s)of clayey soils in conventional ring shear apparatus without suction control, simply by removing water from the shear box while shearing continues and measuring shear strength until its stabilisation, taking place after the specimen in the shear box came to equilibrium with prevailing laboratory atmospheric conditions. Using the chilled mirror hygrometer to measure equilibrium suction after ring shear completion indicated that equilibrium suction due to laboratory atmospheric conditions is practically constant over the time needed for a single test on one soil. This observation along with the previous observation on the linear increase of the ratio tanφres(s)/tanφres(s=0)with suction, makes valid the estimation of evolution of residual shear strength of unsaturated soils with suction using only a conventional ring shear apparatus and a chilled mirror hygrometer. The paper concludes by outlining the approach, presenting measurements and a relation obtained between tanφres(s)/tanφres(s=0), suction and liquid limit.
The importance of unsaturated soil properties in the development of slope susceptibility map for Old Alluvium in Singapore
Authors: Rahardjo Harianto , Li Yangyang , Satyanaga Alfrendo
Published: April 2023

Slope failures caused by rainfall are a regular occurrence in residual soils. As a result of climate change, increased precipitation is anticipated; preventing slope failures due to rain is therefore essential. One typical technique for pinpointing regions at risk for slope failures is the use of a “slope susceptibility map.” Because the groundwater table is usually deep, many slopes in residual soil are typically unsaturated. Soil-water characteristic curve, permeability function, and unsaturated shear strength are the essential unsaturated soil parameters that should be factored into the creation of a slope susceptibility map. This research involved the Old Alluvium region in Singapore as a case study. Transient rainfall infiltration and grid-based regional slope stability (TRIGRS) model was used to establish pore-water pressure distributions over this region. Scoops3D was utilized to include the pore-water pressures calculated by TRIGRS for evaluating slope stability in three dimensions. To assess the reliability of the developed slope susceptibility map, two-dimensional (2-D) numerical analyses were performed on a subset of historically unstable residual soil slopes at the Bidadari site. Minimum safety factors determined via numerical analyses of the slopes under study agreed well with those determined via the slope susceptibility map.
Shear Wave Velocity Response of Compacted Kaolin during Drying-Wetting Cycles
Authors: Walker Christopher , Heitor Ana , Clarke Barry
Published: April 2023

Previous studies indicate that that post-compacted changes in moisture and suction significantly influence small strain response, often this is not routinely monitored during operation. Thus, assessing the impacts of seasonal variation on performance is critical for gauging the geomechanical behaviour of compacted soils underlying typical transport infrastructure. In this paper the influence of drying-wettingcycles on small strain stiffness is investigated on compacted kaolin specimens by measuring shear velocity using ultrasonic testing methods. The drying-wetting cycles were applied to specimens using fixed levels of gravimetric water content. This more closely mimics near surface unsaturated site conditions rather thanadopting fixed suction levels using the axis translation technique. As expected, the results show that the shear wave velocity exhibits a hysteretic response during drying-wetting cycles. However, as the cycles are controlled by gravimetric water content, higher shear wave velocity values were recorded for the dryingpaths rather than wetting paths as previously reported in suction controlled testing. Furthermore, for the subsequent drying-wetting cycle, the shear wave velocity continues to show an hysteretic response while also exhibiting increasing velocities for a given gravimetric water content level, indicating that specimensare undergoing some form of hydraulic ageing.
Investigation of piled foundations in swelling clays
Authors: Gaspar Tiago A. V. , Jacobsz Schalk W. , Osman Ashraf S.
Published: April 2023

This paper presents the results of element testing and centrifuge modelling to investigate the behaviour of piled foundations in swelling clays. The study revealed that the preparation procedure implemented, was able to retain key hydromechanical properties when compared with undisturbed specimens. Furthermore, the preparation method utilised to create an artificially ‘fissured’ fabric allowed for significant swell magnitudes to be achieved in the centrifuge within a reasonable timeframe. Centrifugetesting illustrated that, at lower magnitudes of swell, increases in lateral pressure against a pile shaft can increase shaft capacity. However, if swell is allowed to continue to large magnitudes, the effects of swellinduced softening tend to dominate, thus resulting in a reduction in shaft capacity. The effects of swellinduced softening are more prominent close to the clay surface where swell is allowed to occur more freely. However, at greater depths where swell is restricted, so too are the effects of swell-induced softening, resulting in local increases in shaft capacity at greater depths.
Behaviour of a building foundation on unsaturated expansive soil
Authors: Tika Theodora , Koninis Georgios , Vranna Antigoni
Published: April 2023

The paper presents a case study of the behaviour of a building foundation on expansive unsaturated clay. The load-bearing masonry building started exhibiting severe cracking in its superstructure, immediately after its completion around 1950. Despite the interventions, the problems continued to exist sixty years later. In the context of identifying the causes of these problems, the paper presents the results of the laboratory tests conducted on the expansive clay in order to estimate its swelling pressure and also understand its behaviour. It is shown that the seasonal variation of the water content of the foundation soil, combined with the intrusion of the root system of the nearby trees at the level of the foundation, subjected the soil to wetting-drying cycles, resulting in its corresponding swelling-shrinking and consequently the settlement of the building. Finally, the proposed countermeasures for the solution of problems are presented, which aimed mainly in minimizing the variation of the moisture of the soil around and at the foundation of the building.
Water retention curves and tensile strength for studying desiccation cracking of compacted clay soils
Authors: Ebrahimisadr Hesam , Francois Bertrand
Published: April 2023

Desiccation cracking is a natural phenomenon caused by drying in near-surface earth soils subjected to constrained shrinkage. In this research, the water retention curve of two clayey soils, prepared by compaction under standard proctor conditions, are determined to study the desiccation cracking. Two techniques of suction control are applied to control the drying process and to reach the water retention curve of the soils. For the suction values higher than 4 MPa, the saline-solution method was used to impose variousrelative humidity and so, various suctions. In addition, the osmotic method was applied for the suction values between 0.5 MPa and 2 MPa. Additionally, the dynamic vapor sorption (DVS) technique is used to corroborate the water retention curves obtained with the two other techniques. The volume changes is also tracked showing significant shrinkage upon drying. To reach the tensile strength of the soil, the Braziliantest is performed on samples prepared by compaction and submitted to various suctions. According to the results, for the two tested soils, the soil with the higher plasticity index shows consistently the higher retention capacity and the larger shrinkage upon drying. Also, the obtained water retention curves exhibit a smooth transition when the suction control technique change (at suctions between 2 and 4 MPa).
Soil water retention curves of a silty clayey sand compacted at different dry density
Authors: Ventini Roberta , Pirone Marianna , Mancuso Claudio
Published: April 2023

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.
Impact of Suction on the Near Surface Lateral Soil Response using Centrifuge Modeling
Authors: Komolafe Oladayo , Ghayoomi Majid
Published: April 2023

Recent studies have shown that unsaturated soils lead to greater lateral pile capacity. This study aims to experimentally assess how suction stress affects the lateral response of piles in unsaturated cohesionless soil. Two centrifuge tests were performed at 50 g to evaluate the effect of suction stress in the soil. Lateral loads were applied monotonically on a single free-head pile in a displacement-controlledmanner to a maximum pile head displacement of 0.44 m. The first test was conducted on fully saturated cohesionless soil, while the second test was performed in an unsaturated state with a mixed unsaturatedsaturated soil layer. The water table was lowered to about 0.12 times the embedded pile depth to ensure an unsaturated condition in the zone closer to the surface of the soil. Lateral response assessment indicates that the unsaturated soil influenced the pile head response, leading to larger applied lateral loads for similar pile displacements in comparison to the fully saturated soil test. Experimental findings reveal that suction stress played a meaningful role in magnitudes of pile bending moments and lateral resistances for unsaturated cohesionless soils.
Gaining insight into the effective stress parameter using pore-scale numerical modelling with the multiphase lattice Boltzmann method
Authors: Hosseini Reihaneh , Kumar Krishna
Published: April 2023

We investigate the factors influencing the effective stress parameter, χ, in unsaturated granular soils using pore-scale numerical modelling. The Shan-Chen multiphase lattice Boltzmann method (LBM) is used for this purpose. A procedure is outlined for measuring χ using LBM data. A full hydraulic cycle is simulated for a granular soil column and individual contributions of suction and surface tension forces to χ are measured as a function of the degree of saturation, Sr. It is observed that while χ = 0 at Sr = 0 and χ = 1 at Sr = 1, χ > Sr for 0 < Sr < 1. The trend of the χ-Sr curve is explained based on the trend in the individual components. Schematic plots are utilized to facilitate the understanding of the trends in the data. It is also observed that the χ-Sr relationship is hysteretic; particularly, χ is larger during imbibition compared to drainage, for a wide range of Sr, due to the more pronounced contribution of surface tension forces.
Enhancement of a hydro-mechanical hypoplastic model for unsaturated fine-grained soils accounting for small strain stiffness
Authors: Pico-Duarte María , Mašín David
Published: April 2023

Due to global climate change, larger extreme seasonal and daily moisture variations have been occurring more frequently in the last decades. This phenomenon can affect geotechnical structures by inducing cyclic coupled hydro-mechanical loads. However, reproducing this behaviour from a numerical point of view requires robust constitutive models that can predict the coupling between the hydraulic and mechanical behaviour of fine-grained soils, combined with predictions of history-dependent stiffness evolution at small strains. For this reason, in the present work the hypoplastic model for unsaturated finegrained soils was further modified to better predict the water retention behaviour of unsaturated soils incorporating a smoothed hysteretic Water Retention Curve (WRC). In addition, the constitutive model wascalibrated using experimental data available on the literature of a completely decomposed tuff (CDT) from Hong Kong. At the end, the capabilities of the extended model to predict cyclic behaviour of unsaturated soils were evaluated using cyclic constant water triaxial tests at different suctions The results indicate that the extended model is able to describe with more accuracy the cyclic hydro-mechanical behaviour of the decomposed tuff if additional suction-dependency of one of its small-strain parameters is considered. Without this, the model can be calibrated to data at a given suction but its cyclic predictions for different suctions are not reasonably accurate.
3-Dimensional Numerical Evaluation of Geosynthetic Encased Stone Columns in Unsaturated Soils
Authors: Shakeel Abid Mohammed , Ramana G. Venkata , Vanapalli Sai K. , Muthukkumaran Kasinathan
Published: April 2023

Geosynthetic encased stone columns are often designed using the conventional framework of saturated soils ignoring the influence of in-situ unsaturated soil conditions. This article evaluates the performance of stone columns with and without geosynthetic encasement extending the mechanics ofunsaturated soils. The focus of numerical simulations was directed towards understanding the influence of matric suction on the confining support offered by the surrounding soil to stone columns with and without geosynthetic encasement. Investigations were extended considering the stiffness and the length of the geosynthetic encasement. The numerical studies suggest the load-carrying capacity of stone columnincreased with an increase in the matric suction in the boundary effect and the primary transition zone. However, the contribution of matric suction towards load-carrying capacity starts reducing from the secondary transition zone. The information on boundary effect and transition zones can be derived fromthe soil-water characteristic curve, which is a relationship between the water content and soil suction. In addition, the effect of stiffness and length of encasing material in unsaturated soils was found to be in contrast with saturated soils. The results of the study are promising towards developing procedures thatcan be used in the rational design of stone columns in unsaturated soils.
The effect of stress-dependent SWRC on the load carrying capacity of the slope subjected to the drying-wetting path
Authors: Jadar Chidanand M. , Rajesh Sathiyamoorthy , Roy Suman
Published: April 2023

The stability and load capacity of structures resting on compacted soil slopes is one of the major concerns in Geotechnical Engineering practice. The mechanically compacted earthen slopes are prone to the dynamic exchange of flux flow, resulting in varying saturation levels across their entire configuration. The soil water retention curve (SWRC) is a property which significantly controls the stability and load capacityof structures resting on these compacted soil slopes. The parameters of a typical SWRC are affected by net stress and climatic changes in field conditions, adding more complexity in evaluating the load capacity and stability of structures resting on these compacted soil slopes. To analyze this issue critically, the load capacity of a footing resting on an unsaturated compacted soil slope under year-long arid climatic conditions has been evaluated numerically in the present study. The effect of net stress has been considered by assessing the stress-dependent SWRC of chosen soil under the wetting and drying cycle at various net confinementsof 10 kPa, 100 kPa, and 200 kPa in the laboratory. Key parameters of the SWRCs under drying and wetting cycles were incorporated to evaluate the load capacity of the footing resting on the unsaturated soil slope.
Effect of slope geometry on stability of slope in Almaty
Authors: Satyanaga Alfrendo , Abishev Rezat , Sharipov Assylanbek , Wijaya Martin , Hamdany Abdul Halim , Moon Sung-Woo , Kim Jong
Published: April 2023

Landslides bring destruction to buildings, and nearby located structures and mostly occur in rural areas. Such hazard commonly takes place in mountainous areas in Central Asia. Kazakhstan region has highly vulnerable areas to rainfall-induced landslides in South-Eastern parts due to presence of many mountains. The purpose of the research is to demonstrate the effect of slope geometry on slope stabilityunder heavy rainfall in Almaty, Kazakhstan. Transient seepage analyses were conducted using Seep/W while limit equilibrium slope stability analyses were performed using Slope/W. 15 sets of numerical analyses were carried out on different slope angle and slope height incorporating the soil-water characteristic curve and unsaturated permeability and unsaturated shear strength of soil from Almaty. According to the obtained simulation results in GeoStudio software for seepage analysis, the pore-water pressure is increased almost for 80 kPa at the mid slope of each simulation. The change of FoS for the gentlest slope with 27 degrees slope angle is the lowest for 10 m slope height and the highest for 30 m slope height, whereas the change of FoS for slope with 45 degrees of slope angle (9%) is almost the same for all slope height.
Stability analysis of unsaturated soil slope considering softening and non-softening approach
Authors: Yang Xiuhan , Vanapalli Sai
Published: April 2023

In conventional geotechnical engineering practice, peak shear strength parameters are widely used in the design of geo-structures constructed with or within unsaturated soils. However, a reduction inshear strength from the peak to the residual value is typically observed during the shear deformation in typical fine-grained unsaturated soils. Several geo-structures in unsaturated soils undergo a large shear deformation prior to reaching the failure condition. Thus, the factor of safety of such geo-structures will gradually but significantly decrease with the development of the shear deformation. For this reason, the strain-softening behaviour of unsaturated soils should be considered for reliable design of the geo-structuresin unsaturated soils. In this study, an unsaturated clay slope under 10 years rainfall infiltration were modelled using softening and non-softening approach using commercial finite element software SIGMA/W. The responses of the studied slope to the long-term rainfall infiltration were analysed. The results of the softening and non-softening analysis were compared. This study provides valuable information with respect to the significance of the strain-softening that are useful in the rational design of slopes in unsaturated soils.
Shrinkage cracks of bentonite-zeolite mixtures
Authors: Seah Yew-Heng Sherman , Leong Eng-Choon
Published: April 2023

Bentonite is commonly used in geosynthetic clay liner (GCL) as well as compacted clay liner (CCL) for containment facilities such as sanitary landfills due to its low permeability. Bentonite experiences significant shrinkage on drying, leading to the formation of desiccation cracks and increasing the likelihood of contaminant leachate from the landfill. Adding granular materials such as fine sand to bentonite canreduce shrinkage and hence shrinkage cracks. Recently, zeolite has been suggested as another possible additive to reduce be shrinkage cracks in bentonite. Zeolite has additional benefits of being able to adsorb heavy metals and when enriched with silver, zinc, or copper, it can function as a biocide. The objective of this paper is to present the results of a study on shrinkage crack formation of bentonite-zeolite mixtures during drying. The evolution of shrinkage cracks of the bentonite-zeolite mixtures on drying was studiedusing image processing. The results show that desiccation cracks are at a minimum when the zeolite content is between 15% and 20%. The finding is useful to design more efficient GCL or CCL when zeolite is incorporated into the bentonite layer.
Large scale Vertical SEALing (VSEAL) test: Impact of gas migration on bentonite based vertical seals
Authors: Mokni Nadia , Cabrera Justo , Deleruyelle Frederic
Published: April 2023

The Institute for Radiological protection and Nuclear Safety (IRSN) has launched the VSEAL project to investigate the impact of gas migration on the long-term performance of bentonite based vertical sealing systems. This project relies on in-situ experiments emplaced in IRSN´s Underground ResearchLaboratory (URL) in Tournemire (South France) and small-scale tests conducted in laboratory. The studied material is mixture of MX80 bentonite high density pellets and powder which are being evaluated as possible sealing materials in deep geological repositories. The test is still in progress, but the collected set of data provides already valuable information of the hydro mechanical behavior of Vertical sealing systems during hydration.
Investigation on hydraulic-mechanical properties in bentonite-sand mixture with consideration of salinity water
Authors: Motoshima Takayuki , Iso Sachie , Nishimura Tomoyoshi
Published: April 2023

Bentonite with fine components much such as extremely expansive soil has been commonly required as buffer/backfill materials in order to prevent seepage for construction of further deep geologicalrepository for disposal of high-level radioactive waste (i.e. HLW). The buffer received significant hydromechanical efforts from host rock at underground environment. While the construction/maintenance with long-time operation of a repository, it was predicted that high compacted bentonite will be progressively hydration due to pore water flow or infiltrated from surrounding host rock. The purpose of this study is to establish the connection among the basic mechanical properties, soil retention characters and chemical couple properties under unsaturated condition and saturated conditions for a bentonite-sand mixture. This conducted out some testing programs, which are soil-water characteristic curve test, unconfined compression test, creep test and triaxial compression test for unsaturated sodium bentonite sand mixture and saturated bentonite sand mixture. In addition, the influence of salinity water on mechanical properties is considered with comparison to saturated bentonite sand mixture subjected to swelled due to distilled water.
Calibration of BBM Parameters using the Modified State Surface Approach
Authors: Zhang Xiong , Riad Beshoy , Alonso Eduardo E.
Published: April 2023

The Barcelona Basic Model (BBM) developed by Alonso et al. [1] is the first and the mostwidely used elasto-plastic model for unsaturated soils. The BBM successfully explained many key features of unsaturated soils and received extensive acceptance. However, there is lack of a well-establishedmethod for selecting parameter values for the BBM from laboratory tests, although a variety of methods have been recently developed for calibrating model parameters for the BBM. Concerns still exist on the correctness and robustness of such parameter value selection procedures. The above statements were evidenced by a recent benchmark exercise on selection of parameter values for the BBM organized within a "Marie Curie" Research Training Network on "Mechanics of Unsaturated Soils for Engineering"(MUSE)[2]. Experienced constitutive modelers in unsaturated soils from 7 prestigious teams were provided with the same experimental results on an unsaturated soil to calibrate the parameter values in the BBM. Theoretically, the calibrated parameters from different teams are expected to be the same or at leastvery close. However, the selected parameter values by the 7 teams are surprisingly widely different. This paper first discussed the limitations in the existing methods to calibrate the parameter values in the BBM. A novel approach was then proposed to calibrate the parameter values for the BBM. The approach takes advantage of the close-form solution of the BBM, which is derived based upon a newly
proposed Modified State Surface Approach to study the unsaturated soils [3-6]. The same experimental data, used in the MUSE benchmark exercise, were reanalysed using the proposed approach to calibrate parameters for the BBM. The results were compared with those in the MUSE benchmark exercise from which thesimplicity, effectiveness, and robustness of the proposed method were evaluated.
Stress-strain behaviour of unsaturated compacted coal rejects and tailings
Authors: Buzzi Olivier , Li Jianping , Pineda Jubert , Payne Daniel , Ouyang Kaiwen , Wu Jinbiao
Published: April 2023

The paper presents the results of an experimental study aimed at evaluating the stress-strain response of unsaturated tailings (Mixed Plant Reject and Dewatered Tailings) from a mine in Queensland, Australia, which can be applied to further optimise current tailings disposal strategies of the mine. Triaxialtests at constant gravimetric water content were performed on specimens prepared at different compaction states using dynamic and static methods, to determine their shear strength. The dynamically compactedspecimens display a higher strength than that statically compacted ones, which highlights the significance of stress history for tailings strength. As-compacted and post-testing suction measurements, performed using a high-capacity tensiometer, showed a reduction in matric suction irrespective of the material type, which is caused by mechanical wetting. The strength envelope was found to be non-linear, partly because of suction changes during testing. Post-testing suction measurement showed spatial variability within each specimen, with the central part of the samples experiencing the maximum suction reduction. The paper concludes with a discussion on the interpretation of such results.
Estimations of water retention curves for fine-grained soils and tailings using their fractal particle size distributions
Authors: Jimenez Arturo , Russell Adrian R.
Published: April 2023

A water retention curve (WRC) enables the quick determination of suction in a soil or tailings using the gravimetric water content or degree of saturation. However, establishing the WRC is reliant on time consuming laboratory testing. Here an empirical method is presented that allows the WRC to be estimated quickly, including its void ratio dependency, by relating the fractal and other characteristics of the soil or tailings particle size distributions (PSD) to the parameters which define the WRC. The defining parameters, from a fractal mathematics viewpoint, depend on the particle and pore surface areas and shapes as well as their fractal dimensions. More generally, the clay percentage must also have an important role as it has a major influence on these properties, especially the surface areas. Twelve WRCs for soils and tailings were compiled and compared and used to establish the new empirical expressions. Estimated WRCs using these new empirical expressions compare well with those fitted directly to experimental results. Guidelines are also given on how to quantify suction’s contribution to strength using the location of the hydraulic state on the WRC, adding to the practical appeal of this work.
Evaluation a volumetric water content sensor to be used for compacted filtered iron ore tailings
Authors: Landim Ariane de Sá , Corrêa Yuri , Silva João Paulo , Marinho A.M. Fernando
Published: April 2023

The use of compacted landfills for filtered tailings has grown to replace dams. Considering that this is a structure that must remain in the unsaturated condition, it is necessary to monitor the flow pattern and water retention in these landfills. The use of sensors for the automatic monitoring of volumetric water content is a fundamental tool for use in the field. Sensors that use the technique called FDR (Frequency Domain Refractometry) emit an electromagnetic signal that, associated with the ability of materials to store electrical charge, allows the determination of the so-called dielectric constant. The dielectric constant relates the capacitance of the material to the capacitance of the air. As the dielectric constant in air is, by definition, equal to 1 and of the water, at 20 degrees Celsius, equal to 80, materials with a range proportion of air and water have variable dielectric constant values, considering the dielectric constant of minerals being constant. Many commercial sensors already come with a calibration curve that is based on typical soils (quartz and feldspar). However, in the case of iron mining tailings, in addition of having a very different mineral composition from the soils normally founded, there is the possibility that the presence of very fine particles could alter the dielectric constant of the liquid. In this way, it is essential to obtain a specific calibration curve, taking into account not only the material, but also the density of it. The sensor used in the present study is the TEROS 12. The results obtained for the sensor calibration in the case of iron ore tailings, demands a specific calibration to be performed for the material and each density to be used. The process used for the calibration and the equations obtained are presented in this paper.
Unsaturated shear strength parameters for a compacted iron ore tailings
Authors: Hora de Jesus Michelli , Serafim Rodrigo , Silva João Paulo , Marinho Fernando A. M.
Published: April 2023

The use of iron mining tailings in compacted landfills is expected to expand more and more to replace the placement of tailings in dams. With this, the unsaturated condition of these materials becomes of great importance for the safety of the structures executed with them. In addition to tests in the saturated condition, and with the objective of simplifying the determination of strength parameters in the unsaturated condition, direct shear tests with constant water content were performed. Data of physical and chemical characterization of the tailings, and the water retention curve at the compacted state and continuously disturbed condition are also presented. The latter aims to evaluate the effect of the shear process on the final suction of the material. The results suggest that there are no significant variations in suctions during the failure process and that, in this case, the initial suction can be assumed to be the same as the one at failure. The shear strength parameters indicate a high friction angle, which does not vary with suction. With the data obtained, it was possible to apply the model of Vilar (2006) to obtain the shear envelope with suction. The results presented aim not only to expand the database of iron ore tailings parameters, but also to present a procedure for the application of tests with constant water content.
Numerical study on the effects of groundwater table oscillation beneath the “Palazzaccio” courthouse in Rome
Authors: D’ Alessio Gorizia , Pucci Arianna , Guida Giulia , Casini Francesca
Published: April 2023

This work aims to evaluate the settlement induced by the river Tiber groundwater table oscillations. A representative section of the subsoil beneath the courthouse “Palazzaccio”, close to the river in the city centre of Rome, is analysed via the finite element method with a fully coupled hydro-mechanicalmodel. The effects of wetting-drying cycles induced by the water table oscillation are accounted for by adopting the Barcelona Basic Model for the unsaturated layers, whose model parameters are calibrated using experimental results on saturated and unsaturated samples and literature data. The variation of the river Tiber level is reconstructed according to the “Tevere – Ripetta” hydrometric station records between 2005 and 2008, and it is applied as a boundary condition at the boundary of the model domain.