Limites d'Atterberg | EPFL Graph Search

vignette|Figure schématique indiquant la position relative des limites d'Atterberg et de l'indice de plasticité. En géotechnique, les limites d’Atterberg définissent à la fois un indicateur qualifiant la plasticité d’un sol, mais aussi l’essai qui permet de définir ces indicateurs. Cet essai a été établi par l’agronome suédois Albert Atterberg. La teneur en eau d’un sol peut en effet beaucoup varier au cours des opérations de terrassements. Pour la fraction fine (graviers exclus), la cohésion tient à la présence d'eau : parfaitement sec, le matériau serait cohérent. Au-dessus d'une certaine teneur (limite de plasticité), on peut le pétrir en forme de boudin, de boulette ou de fil. Pour une teneur plus forte (limite de liquidité), il forme un liquide, visqueux, qui ne conserve pas la forme qu'on lui a donnée. La détermination, soigneusement normalisée, de ces deux teneurs caractéristiques appelées limites d'Atterberg, est un élément important d'identification, et permet déjà de prévoi

Evaluation of the tensile strength of SFRC as derived from inverse analysis of notched bending tests

Aurelio Muttoni

For the design of SFRC members, the most fundamental material property is its post cracking residual tensile strength. When relying on physical models to describe structural behaviour under load, the material laws must first be accurately established. If the material laws either significantly over- or under-estimate the residual tensile capacity of the SFRC, an accurate physical model for the determination of its strength is not possible. However, in production control and materials specification, direct tensile testing is costly in time and difficult in that it requires specialised testing equipment. To this end, testing of prisms in bending is often substituted for uniaxial tension testing, and empirical design models are developed based on the results. Several attempts have been undertaken to provide an inverse analysis from prism data to establish the σ-w relationship but no direct test verification of the approaches have, to date, been established. This paper compares the results for σ-w relationship obtained from a direct tension test with those obtained using prism tests combined with an inverse analysis. Finally, a model is proposed that can be used for control testing with designs established using physically based models for strength limit states.

VIII International Conference on Fracture Mechanics of Concrete and Concrete Structures, FraMCoS-82013

Global Prediction of Soil Saturated Hydraulic Conductivity Using Random Forest in a Covariate‐Based GeoTransfer Function (CoGTF) Framework

Dani Or

Saturated hydraulic conductivity (Ksat) is a key soil hydraulic parameter for representing infiltration and drainage in land surface models. For large scale applications, Ksat is often estimated from pedotransfer functions (PTFs) based on easy-to-measure soil properties like soil texture and bulk density. The reliance of PTFs on data from uniform arable lands and the omission of soil structure limits the applicability of texture-based predictions of Ksat in vegetated lands. To include effects of terrain, climate, and vegetation in the derivation of a new global Ksat map at 1 km resolution, we harness technological advances in machine learning and availability of remotely sensed surrogate information. For model training and testing, a global compilation of 6,814 geo-referenced Ksat measurements from the literature was used. The accuracy assessment based on spatial cross-validation shows a concordance correlation coefficient (CCC) of 0.16 and a root mean square error (RMSE) of 1.18 for log10 Ksat values in cm/day (CCC = 0.79 and RMSE = 0.72 for non-spatial cross-validation). The generated maps of Ksat represent spatial patterns of soil formation processes more distinctly than previous global maps of Ksat based on easy-to-measure soil properties. The validation of the model indicates that Ksat could be modeled without bias using Covariate-based GeoTransfer Functions (CoGTFs) that harness spatially distributed surface and climate attributes, compared to soil information based PTFs. The relatively poor performance of all models in the validation (low CCC and high RMSE) highlights the need for the collection of additional Ksat values to train the model for regions with sparse data.

2021

Search for new phenomena with multiple charged leptons in proton–proton collisions at $\sqrt{s}= 13$ $\,\text {TeV}$

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Alexandre Aubin, Roberto Castello, Juan Ramon Castiñeiras De Saa, Yixing Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Alessandro Degano, Charles Dietz, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Alexis Kalogeropoulos, Viktor Khristenko, Ji Hyun Kim, Donghyun Kim, Vineet Kumar, Ajay Kumar, Sanjeev Kumar, Ekaterina Kuznetsova, Wei Li, Ho Ling Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Sourav Sen, Varun Sharma, Ashish Sharma, Lesya Shchutska, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Xin Sun, Marco Trovato, Andromachi Tsirou, Paul Turner, Joao Varela, Yi Wang, Zheng Wang, Siyuan Wang, Jian Wang, Mingkui Wang, Qian Wang, Hui Wang, Rui Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

Results are reported from a search for physics beyond the standard model in final states with at least three charged leptons, in any combination of electrons or muons. The data sample corresponds to an integrated luminosity of 2.3

\,\text {fb}^{-1}

of proton–proton collisions at

\sqrt{s} =13

\,\text {TeV}

, recorded by the CMS experiment at the LHC in 2015. Two jets are required in each event, providing good sensitivity to strong production of gluinos and squarks. The search regions, sensitive to a range of different new physics scenarios, are defined using the number of jets tagged as originating from bottom quarks, the sum of the magnitudes of the transverse momenta of the jets, the imbalance in the overall transverse momentum in the event, and the invariant mass of opposite-sign, same-flavor lepton pairs. The event yields observed in data are consistent with the expected background contributions from standard model processes. These results are used to derive limits in terms of R-parity conserving simplified models of supersymmetry that describe strong production of gluinos and squarks. Model-independent limits are presented to facilitate the reinterpretation of the results in a broad range of scenarios for physics beyond the standard model.

2017

Search for new phenomena with multiple charged leptons in proton–proton collisions at $\sqrt{s}= 13$ $\,\text {TeV}$

\,\text {fb}^{-1}

of proton–proton collisions at

\sqrt{s} =13

\,\text {TeV}

2017